Date: Thu, 2 Jan 1997 15:32:09 -0500 From: INFINITY Aerospace <72124.347@compuserve.com> Subject: COZY: Cooley Hat and 4-Way Trim Switch Hi Steve, >Steve Wright here---I need the "cooley hat" switch you put on your stick grips. Where can I buy one .......can you sell me one. How does it work?< I take it you are going the purist route (building your own grip - send me pics when you are done for my scrap book). The switch I use is a 4-way switch, momentary in all directions, and springs back to the center, just like the $100 to $200 dollar mil-spec switch does, except my switch is good for 500,000 activations. The mil-spec switch is good for 100,000 activations. Also, this type of switch movement cannot get stuck under a surface causing run-away trim emergency situations like other trim switches on other attempts at making stick grips have. It takes 40 ounces of force to move the mil-spec switch in any direction, a little too hard for our small airplanes - Burt thought so too (you'll probably move the stick when all you wanted to do was trim the plane). My switch is only 11 ounces of force in any direction, a nice lite touch. The cooley hat itself is the same size as used on the mil-spec grips, but the steps making the hat are "V's" on my cooley hat, not just steps. So my cooley hat bites into your thumb a little better, instead of your thumb possibly slipping off the cooley hat when trimming. I can send you a switch and cooley hat for $10 total, plus shipping and handling - about $3, plus tax (if applicable). HTH. Infinity's Forever, EAA Member EAA Technical Counselor JD EAA Flight Advisor AOPA Member Test Pilot James D. Newman, President LCDR F-14 USNR INFINITY Aerospace Mailing Address: P. O. Box 12275 El Cajon, CA 92022 Shipping Address: 1750 Joe Crosson Drive, D-2 El Cajon, CA 92020 (619) 448-5103 PH & FAX 72124.347@compuserve.com OR INFINITY_Aerospace@compuserve.com Home Page http://ourworld.compuserve.com/homepages/INFINITY_Aerospace Date: Fri, 10 Jan 1997 14:48:02 -0500 (EST) From: AlWick@aol.com Subject: COZY: el cheapo strobe Been looking for alternatives to some of the expensive items for my plane. Found portable strobe at a marine supply store. It's intended to attach to your life vest, powered by three AA batteries (which last 24hrs reportedly). I tried it at store, still seeing spots in front of my eyes. $60 I would consider adapting it to aircraft power supply, or could keep it stock and power remotely with batteries in cockpit. I would make it readily accessable in case of replacement need. Would appreciate any comments. -al Date: Wed, 25 Jun 1997 07:34:38 -0400 From: David Domeier Subject: COZY: Master Relay Temperature I=92ve noticed, in the process of wiring my MKIV, that the master solenoid (Wicks part number 70-111226-5) gets very warm after about 5 minutes when closed. In fact, I will go so far as to say it gets hot to touch. If some of you all don=92t mind, how =91bout checking your master relay = for temperature. I=92ve talked to shop mechanics and no one seems to know ho= w warm a master relay should be. I have a second relay on hand and in bench checking it with a battery charger, it gets just as hot as the one in the airplane. Thanks. dd ps As far as I know there's only one way to hook up a master relay, battery to the battery pole and ground switch to the small lug. Date: Wed, 25 Jun 1997 18:25:22 -0400 From: Jim Hocut Subject: Re: COZY: Master Relay Temperature While I've never laid my hands on an aircraft master relay after it's been energized for a while, I am a EE and have used a relay or two in my work. It's just the nature of the beast, they get warm (sometimes quite warm) after being energized for a while. The coil has some small resistance, so you're producing several watts of heat while it's on. -- Jim Hocut jhocut@mindspring.com Date: Tue, 1 Jul 1997 10:44:09 -0400 (EDT) From: CozyBldr@aol.com Subject: COZY: Canopy & Wayne's Breaker Panel I'm presently building the canopy and I've noticed that there is not much room forward of the instrument panel under the plexi itself. I'm planning on using Wayne Lanza'a breaker panel but I saw one a few years ago and I seem to recall it being larger than the space I have under the canopy. Has anyone else installed the panel and did any problems arise from not enough space? Thanks. Paul Stowitts Cozy Mark IV #200 Date: 01 Jul 97 22:58:14 EDT From: "Edmond A. Richards" <103235.1336@compuserve.com> Subject: Re: COZY: Canopy & Wayne's Breaker Panel Paul, I have Wayne's breaker panel installed and it fits perfect under the canopy. I had the same concern while building the canopy so I wrapped the breaker panel in plastic and installed it in the instrument panel during the building. There is very little space but it all fits. I also left the unit in place while I made the small cover that must fit over top of the instrument panel and provide the space to house it. Ed Richards Cozy Mark IV #088 Date: Sat, 05 Jul 1997 10:04:10 -0400 From: David Domeier Subject: Re: COZY: Canopy & Wayne's Breaker Panel Paul, I just completed installing mine and it has about an inch of clearance to canopy. dd MKIV #155 From: Marc J. Zeitlin Subject: COZY: canopy, nose gear, throttle switch circuit Date: Wed, 20 Aug 97 17:03:06 EDT People; Well, we're going to buy a house with a 2-car garage so that I can get the dang plane out of the basement and assemble it. However, it won't be finished (the house, that is) until March at the earliest, so I'm spending the next six months installing random little stuff, like the electrical system and the instrument panel :-). At any rate, while studying chapter 22 for installation of the warning buzzer/light circuit for the canopy/gear/throttle, I've become confused (not being an E.E.). I can understand the logic of the three microswitches, and the function of the wiring for the warning buzzer and light, and I understand how the momentary push button turns off the buzzer while leaving the light on _WHILE THE BUTTON IS DEPRESSED_. What I don't understand is how the circuit latches so as to keep the warning buzzer off, while leaving the light on. Does the relay have an internal latching circuit? Am I missing something in the wiring diagram? Why wasn't this implemented with cams and gears - then I'd understand it :-). Is this some special type of relay that's used (heck if I can find "Colectro" relays anywhere) - does someone have a source for these things - Digikey, Mouser, Radio Shack?. Thanks in advance for the electrical tutorial. Also, I've purchased Bob Nuckolls' $35 book on aircraft electrical systems (discussion ongoing in the canard-aviators mailing list, and web page at http://www.aeroelectric.com) and it has a wealth of incredibly useful information regarding electrical systems. Bob also sells many useful items from his web page - check it out. P.S. - I've got my instrument panel laid out in my CAD system. I can make a DXF file, if anyone's interested - I've got the standard 3-1/8" and 2-1/4" instruments at true size, and the radio stack at the correct width (height is dependent on vendor). I've got the air vents that Nat recommends in place as well. I'm assuming all non-electronic instruments at this point (no $3K Vision Microsystems stuff), and it's amazing what you can pack into one of these panels with a little judicious shuffling, and with assuming that the fuse block and/or breakers go behind the panel, rather than in it. If there's enough response, I'll put it on the web pages and make it available for email download, but it's a work in progress at this point - it changes every few days. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Wed, 20 Aug 1997 19:34:25 -0700 From: Michael Antares Subject: COZY: canopy, nose gear, throttle switch circuit Marc, I'll attempt to answer your question about the circuit: Simply put, the relay is held latched by a rather convoluted path which starts at the ground connection located to the right of the push button (this is symbolized by the three decreasing length horizontal short lines--this is the return path of the 12V battery). This ground path goes to the "c" (common) connection of the throttle micro switch which will connect to the "nc" (normally closed) contact when the throttle is advanced and then to the "nc" contact of the canopy switch and to the "c" contact of the switch when the canopy is not locked. From this "c" contact it goes to the "c" contact of the relay and then to the "no" (normally open) contact (the relay has been energized by the push button). The relay "no" contact goes to the lower side of the relay coil and this will keep it energized since the top lead is going direct to 12V. The relay will be released by locking the canopy or closing the throttle. You can follow a similar path in regards to the gear microswitch. I hope this helps... Michael 6077 Old Redwood Highway Penngrove, CA 94951 707.792.7971 Systems engineering hardware/software Date: Wed, 20 Aug 1997 19:37:22 -0700 From: Michael Antares Subject: COZY: canopy, nose gear, throttle switch circuit A short PS: No, this is not a special relay. Almost any 12V DC relay will work as the contacts only need to carry the horn current (check the horn operating current and choose a relay that has a contact rating equal to or greater than the horn current (I would guess less than 1 amp). Michael From: SMilesCozy@aol.com Date: Wed, 20 Aug 1997 23:17:20 -0400 (EDT) Subject: Re: COZY: canopy, nose gear, throttle switch circuit In a message dated 97-08-20 17:05:38 EDT, you write: > What I don't understand is how the circuit latches so as to keep the > warning buzzer off, while leaving the light on. Does the relay have an > internal latching circuit? Am I missing something in the wiring diagram? > Why wasn't this implemented with cams and gears - then I'd understand it > :-). Marc, When relay-D1-974's coil is energized, it breaks the circuit for the horn...while "making" the circuit that energizes the coil. The NO contacts, (now closed) complete this circuit, keeping the contacts closed after the momentary contact switch is released, thereby "latching" it electrically. As soon as any of the micro switches are "opened" the coil in relay-D1-974 de-energizes and enables the horn again. Hope this helps, Steve Miles Cozy MkIV 272 Date: Thu, 21 Aug 1997 09:16:37 +0200 From: morten@scandisoft.no (morten scandisoft.) Organization: ScandiSoft AS Subject: Re: COZY: canopy, nose gear, throttle switch circuit Marc J. Zeitlin wrote: > At any rate, while studying chapter 22 for installation of the warning > buzzer/light circuit for the canopy/gear/throttle, I've become confused > (not being an E.E.). I can understand the logic of the three > microswitches, and the function of the wiring for the warning buzzer and > light, and I understand how the momentary push button turns off the > buzzer while leaving the light on _WHILE THE BUTTON IS DEPRESSED_. > > What I don't understand is how the circuit latches so as to keep the > warning buzzer off, while leaving the light on. Does the relay have an > internal latching circuit? Am I missing something in the wiring diagram? > Why wasn't this implemented with cams and gears - then I'd understand it Mark ! I've just redone my electrical warning system on my Cozy MKIII LN-USA. A lot of Long-Eze/Cozy builders say that they even forget to lower the nose gear because the original system provides a button to silence the warning buzzer. The fail-safe cheap solution I did: install the 3 micro-swiches as per drawing. Connect as per drawing and coupole a USD 2 buzzer and 5 mm dia LED with resistance (radioshack will know the capacity) in PARALELL. I had the electronic gadget with delay timer and push button. Have it still but do not intend to use it anymore. Now the system works and if the buzzer and warning light comes on, something is wrong, and should be corrected immediately. No reset-swich for me and I won't miss it. The total cost for 3 micro-swiches and a LED+resistance was around USD 10. From: lschuler@cellular.uscc.com Date: Thu, 21 Aug 97 12:08:15 -0600 Subject: COZY: canopy, nose gear, throttle switch circuit --simple boundary Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Marc wrote: >snip >Thanks in advance for the electrical tutorial. >snip You are welcome in advance of the below. Hope the following isn't too confusing (I understand it.... :-) ). 1. The circuit will work as shown and as described in the plans (if you can find the parts) and manage to identify the switch and relay contacts correctly when wiring it up. Radio Shlock has some nifty little pre-wired aligator clips that may be handy for testing stuff like this before commiting to solder. 2. In the following, remember that with the 5-Amp circuit braker closed, there is "always" +12 Volts applied to one side of the horn, the light, and the relay coil. The ground (or negative[-]) is what is switched or changed around in order to turn stuff on/off in the circuit. The +12 Volts comes in at the circuit breaker shown at the top, left of the wiring diagram. In order for anything to "work", you must have a plus on one side (12 Volts in this case) and a minus on the other. [Ground is shown in this drawing; but not really accurate for something not tied to or even sitting on the earth, but thats another issue]. Think of it as the "negative" (-) side of the battery and you will be ok. 3. The drawing shown on page 22-4 shows the canopy closed, the gear is up and the throttle is at or near idle. As such, there is a complete ground path through all the micro switches to the horn and lamp. The ground path starts at the symbol shown roughly as: | ----- --- - 4. The three micro switches are wired in the form of a logic "AND" gate if you understand the term. All contacts must be closed (as shown) in order to turn on the horn and lamp. If any one of them opens, the lamp and horn will be turned off. Simply means that if I am slowing down (throttle is at idle) and the gear is still up, I could open the canopy, put the gear down, "OR" increase RPM from idle to turn the lamp and horn off. 5. The ground (-) which triggers the horn is routed through the normally closed (NC) contacts of the relay. The "NC" contacts of 'any' relay are closed when the coil is de-energized (no juice flowing through the coil). In a like sense, the normally open (NO) contacts are Open when there is no juice through the coil. The point on the relay marked "C" is 'C'ommon to both the NO and NC points; this is what essentially moves when the relay coil is energized or de-energized. 6. The relay coil will be energized if the momentary (spring loaded) kill switch is temporarily closed. This, in effect, moves the "C" (Common) lead from the 'NC' point to the 'NO' point. The 'NC' point "WAS" supplying the needed ground (-) to one side of the horn, but this is removed, so the horn stops. Instead, the ground (comming via the "C" on the relay) will go back to the same side of the relay that the swich is connected to; this is make the relay "Hold" or stay energized when you take your thumb off the kill button. 7. Nat says that if you cycle the throttle you will reset the horn circuit. This is true; it will open the ground (-) path going through the throttle switch (remeber, it is shown in the "idle" position). The same thing would happen if you lower the gear "OR" open the canopy. 8. Key to remember that ALL THREE switches must be "Closed" in order to turn on the light bulb and start the alarm. Without any (single) one of the switches in the "open" condition, the lamp goes out and the buzzer stops. I looked in my last copy of the Digi Key catalog (# 965 last fall) and found quite a few relays that would work. Nat doesn't provide any mounting information (go figure), so I can't tell you which would work best. Depends mostly how you want to mount the darn thing. Here is the important elecrical stuff to look for: Coil must be rated at 12 Volts or have an operating range that covers our aircraft electrical system (most are 14 volts or so). Try to find one that has at lease 500 Ohms coil resistance (750 or 1,000 is better) if that is listed; if not, look for the 'smallest' coil current rating (usually in mili-amps (mA). The contacts should have a Minimum rating that will handle the current they will be expected to carry. Without the lamp specs, the horn specs and the relay coil specs, I can't give accurate guidance; but here is a SWAG: the circuit breaker is shown as 5 Amps; I would 'guess' that the max current will be less than that, say 2 or 3 Amps at the "most". This is 'probably' adequate for the contact rating. Look for one that is marked "SPDT" (Single Pole, Double Throw). One marked as "DPDT" (Double Pole, Double Throw) will work just as well, but you will have a couple extra wiring pins you won't need. DO NOT get one that is marked "SPST" (Single Pole, Single Throw); that type ONLY has an NO 'or' an NC set of contact, but not both; you need both with a Common between. If you have the same catalog, try to identify one or two that you think will work and let me know. I'll let you know if it will work or not. Larry Schuler, #500 Ch 8/9 (Still) lschuler@cellular.uscc.com --simple boundary Content-Type: text/plain; charset=US-ASCII; name="RFC822.TXT" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="RFC822.TXT" Received: from gatekeep.uscc.com by cellular.uscc.com (ccMail Link to SMTP R8.00.01) ; Wed, 20 Aug 97 16:07:52 -0600 Return-Path: Received: from www.uscc.com (ns.uscc.com [204.179.101.2]) by gatekeep.uscc.com with ESMTP id RAA10152 for ; Wed, 20 Aug 1997 17:04:44 -0400 (EDT) Received: from palrel1.hp.com (palrel1.hp.com [156.153.255.235]) by www.uscc.com with ESMTP id QAA21778 for ; Wed, 20 Aug 1997 16:04:12 -0500 (CDT) Received: from hpwarhw.an.hp.com (hpwarhw.an.hp.com [15.57.193.122]) by palrel1.hp.com (8.8.6/8.8.5) with SMTP id OAA15244 for ; Wed, 20 Aug 1997 14:06:05 -0700 (PDT) Received: by hpwarhw.an.hp.com (1.37.109.8/15.5+IOS 3.22) id AA16928; Wed, 20 Aug 1997 17:03:08 -0400 Received: by hpwarhw.an.hp.com (1.37.109.8/15.5+IOS 3.22) id AA16920; Wed, 20 Aug 1997 17:03:06 -0400 From: "Marc J. Zeitlin" Message-Id: <9708202103.AA16920@hpwarhw.an.hp.com> Subject: COZY: canopy, nose gear, throttle switch circuit To: cozy_builders@hpwarhw.an.hp.com (Cozy MK-IV Builders) Date: Wed, 20 Aug 97 17:03:06 EDT Mailer: Elm [revision: 70.85] Sender: owner-cozy_builders@hpwarhw.an.hp.com Precedence: bulk Reply-To: "Marc J. Zeitlin" --simple boundary-- by x9.boston.juno.com (queuemail) id QmG23621; Fri, 22 Aug 1997 16:39:24 EDT Date: Thu, 21 Aug 1997 18:35:21 -0400 Subject: COZY: Gear Alarm From: unick@juno.com (Nick Ugolini) I installed a simple redundent alarm for my gear after joining the "gear up" club. I purchased a LOUD alarm from radio shack ($12). I installed a micro switch on my belly board that closes when the belly board is extended. I ran a wire from my power bus through the micro switch on my gear (NC when gear is up) to the micro switch on the board (NO when the board is retracted) to the alarm and to ground. pwr----------gear (NC gear up) -----------board (NO board retracted) -------horn-----ground This is a INDEPENDENT system which alarms if I extend the board with the gear up. No matter what is going on around you during landing (talking a buddy through the landing as in my case), when you extend the board (which you ALWAYS do when on final to slow down) it will let you know if your gear is up... Total cost $15, time to install 2 hrs. Remember the quote of someone famous.... There are two kind of retractable gear flyer... Pilots who have landed with their gear up, and those who will.." From: "Frank" Subject: COZY: BREAKER PANELS Date: Sat, 23 Aug 1997 00:25:39 -0400 HI Mark Got your reply and have been thinking it over. There have been several times when the breaker panels have helped make a flight safe and helped the trip to be completed that would otherwise have a major problem. Or not ended well at all! I dont know how much time your frind has and may be he has been very lucky and not had major emergencys. But if you fly alot with diferent planes you can not always control the maintance the way you would like and the odds do catch up with you. I realy do hope that every one can fly with a good gardian angle and may your friend continue to be so lucky, however we should all be as prepared as we can. Last week a pilot friend of mine who flys for a comuter air line,and has military time in many craft ( I have a good deal of time in the seat beside him and would not hesitate to have my family fly with him ) was bringing a piper lance home from n.y. to Maine.45 min. into the trip the panel lights went dark as the main bus breaker poped ( over the mountain of new hampshire at night ).A remote breaker would have made this imposible to solve, a fuse is hard to change in the dark a local breaker is easy to reset. He turned off all the radios and lights and all electrical systems not critacal to flight and reset the breaker, it held ! He then turned on the systems one by one watching the amp meter for load . Each item by it self was ok except for the pito heat wich was greater than normal well as he said dam*** high. But by it self would not trip the breaker it was on, or the main. But with every thing else on it was enough to take the main out. The trip was completed with the pito heat and one radio bank off to keep system load in limits.Landing lights were not used. The battery was found to be the cause of the problem. The pito breaker was replaced because it did not trip and made him nervous so as he said for pease of mind it went. ( as voltage drops amperage rises ). Several years ago I was flying a twin seabee when I went to lower the gear the breaker would pop, after three atempts I lowered it with the hand pump. The motor had to be changed. But in this case the breaker was a good visual indicatur of the problem. Hidden away I would have only known that the gear would not go down but not why.Knowing the problem apeared to be electrical in nature I used the hand pump and left the geared down untill we landed and it could be checked and fixed. Breakers should be used, not fuses and should not be hinden or tucked away out of reach, or out of site. You your family and passengers depend on your choises now and in the future. Please give them every chance you can. I hope you dont over work your gardian angle! What is that old saying? A WORD TO THE WIZE! IF ANYTHIN CAN BE DONE TO MAKE OUR DREAMS SAFE LETS DO IT SO WE CAN DREAM ON FOR MEANY YEARS TO COME! Best wishes always Frank Johanson From: "Frank" Subject: COZY: breaker panels frank to mel Date: Sat, 23 Aug 1997 17:45:49 -0400 Hi mel You missed the mark by a long shot. I was trying to point out the benifit of a breakers over fuses and not having them hidden out of reach. Not to get into a battle over science. I will however answer your question and hope that at this point we can look at what the objective was to start with, to give real life reasons for a good handy breaker panel. The reason that your formula is wrong is that you did not allow for twin alternaters and a voltage regulator trying to make up for the shorted batteries low voltage. There is more info not mentioned here because it takes us further away from the original topic. Truce ok. Best Wishes Frank Johanson From: "Steve Campbell" Subject: RE: COZY: Electrical Date: Wed, 10 Sep 1997 13:06:01 On Wed, 10 Sep 1997 12:31:17 -0500, EpplinJohnA@JDCORP.deere.com wrote... >... What if the >vacumn line was used as the ground buss? I havn't really done any >research concerning the resistence of 5052 al. tubing but I think it >would probably suffice for several amps. Anybody have any reasons why >this may be a bad idea? > The tubing certainly could carry the current. Not saying that it's not a good idea, but the first problem that comes to my mind is ensuring a reliable contact to the tube. You no doubt remeber Al wiring in houses. The contact get warm from joule heating, it oxidizes, the resistance increases, it oxidizes more, etc. I believe that it is possible, but not easy, to make reliable electrical contacts to Al. Steve ************************************************ Stephen A. Campbell, Associate Professor, ECE University of Minnesota 200 Union Street Minneapolis 55455 (612) 625-5876 phone / (612) 625-4583 fax Campbell@ee.umn.edu ************************************************* From: Epplin John A Subject: COZY: Electrical Date: Wed, 10 Sep 1997 12:31:17 -0500 I have a crazy thought concerning ground wiring. The battery and alternator etc are located near the firewall and have rather short connections, however a good part of the load is distributed at the forward section, near the instrument panel. This means a rather substantial ground conductor must be run the length of the a/c, some bit of weight. Most of the Cozys I have seen have vacumn gyros installed which means a vacumn line running the length of the a/c. What if the vacumn line was used as the ground buss? I havn't really done any research concerning the resistence of 5052 al. tubing but I think it would probably suffice for several amps. Anybody have any reasons why this may be a bad idea? John Epplin Mk4 #467 From: Marc J. Zeitlin Subject: COZY: Electrical (fwd) Date: Wed, 10 Sep 97 13:56:58 EDT John Epplin wrote: >..... What if the >vacumn line was used as the ground buss? I havn't really done any >research concerning the resistence of 5052 al. tubing but I think it >would probably suffice for several amps. Anybody have any reasons why >this may be a bad idea? Yeah, aluminum's not as great a conductor as copper. However, you do have a good idea here, which has been thought of and used before in a slightly different incarnation. One of the suggestions in Bob Nuckolls' book is to use copper plumbing tubing, crimped at both ends and with big honking tabs soldered to them as the ground run in composite aircraft. Copper is a much better conductor than aluminum. You could combine these two ideas, use 1/2" copper tubing for your vacuum line (with appropriate fittings on each end), solder tabs to the outside, and also use it as your ground line. The copper tubing is also easier to bend to the right shape, although that's not a really big deal. On the other hand, if all you're powering is the panel and strobes (the battery is in the back), the 5052 might be OK. If the battery is in the nose, then you really need something with a lot of current carrying capacity, which would argue for the large diameter copper. -- Marc J. Zeitlin Email: marcz@an.hp.com Subject: Re: COZY: Electrical Date: Wed, 10 Sep 1997 14:00:47 -0400 (EDT) From: "Randy Smith" > which means a vacumn line running the length of the a/c. What if the > vacumn line was used as the ground buss? I havn't really done any > research concerning the resistence of 5052 al. tubing but I think it > would probably suffice for several amps. Anybody have any reasons why > this may be a bad idea? Well, it may be hard to pull a vacuum with all that wire clogging up the vacuum line. :-) I'm sorry, I couldn't resist. (Oooo, another pun!) > > John Epplin Mk4 #467 > Seriously, I think this would be a neat idea. Just make sure the connectors on each end are high quality and that they wouldn't crush the vacuum line. -Randy Smith From: Kelly Russell Subject: RE COZY: Electrical Date: Wed, 10 Sep 1997 11:04:16 -0700 >........What if the >vacumn line was used as the ground buss? I havn't really done any >research concerning the resistence of 5052 al. tubing but I think it >would probably suffice for several amps. Anybody have any reasons why >this may be a bad idea? Yes, ground loops (i.e. NOISE). Read Bob Nuckolls 'Aero Electric Connection' for a good explanation and a suggested electrical system layout. Basically Bob suggests that you use copper tubing as the ground and run your wires etc. inside it to get from the back to the front. Jim Hocut jhocut@mindspring.com (via borrowed e-mail account at work) From: Epplin John A Subject: RE: COZY: Electrical (fwd) Date: Wed, 10 Sep 1997 13:07:51 -0500 > You could combine these > two ideas, use 1/2" copper tubing for your vacuum line (with > appropriate > fittings on each end), solder tabs to the outside, and also use it as > your ground line. > -- > Marc J. Zeitlin Email: marcz@an.hp.com [Epplin John A] Thanks for the thoughts. This though had crossed my mind also. One could use steel bulkhead fittings, sleeves and nuts, at each end and flare the copper tube. This would carry the vacuum through to aluminum or hose fittings without a al to cu junction. Tabs could be soldered to the copper for the electrical connections. Think I just might do that. John Epplin Mk4 #467 Date: Wed, 10 Sep 1997 14:37:07 -0700 From: Jim Cullen Subject: COZY: Use of Copper Tubing for a Ground Bus Regarding the discussion on running wires inside a copper tube that acts as a ground bus... I read this recommendation by Bob Nickols several years ago and there was something that always bothered me about it. If any of the wires inside the tube are hot (energized) and if, by rubbing against whatever they would happen to abrade their insulation, you'd have a good opportunity for a short on your hands inside the confines of the tube. I've always wondered if it might not be better to run hot lines down one side of the aircraft and the ground bus down the other. Just a thought... by x9.boston.juno.com (queuemail) id SEH04464; Thu, 11 Sep 1997 18:29:09 EDT Date: Wed, 10 Sep 1997 18:33:50 -0400 Subject: Re: COZY: Electrical From: unick@juno.com (Nick Ugolini) In Bob Nuckells book (my personal wiring bible), he does have a drawing with the copper tubing as the ground bus with the positive wire running through the center to reduce electrical noise. Tabs are just soldered to the sides and your connectors are attached to them. In lu of this type of setup he suggests running your power wires along one side of the plane (twist the wires two turns per foot), and all your data wires (the ones carrying information EGT/CHT etc) along the other side of the plane. I thought about your idea and the possiblity of using the tubing with a power wire (sealed at both ends) along with the vacuum running with the wire.... But on second thought use the tubing for the shelding potential, with your power wires through the center and plastic tubing for your vacuum. It only took me 2 min to run my vac tubing at about $5.00 in materials. Can't beat it. Personally I used twisted power wires on my long, shielded wires for EVERYTHING else, and I have NO electrical noise at all. From: "Rob Cherney" Date: Wed, 10 Sep 1997 21:13:20 -0400 Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Jim Cullen wrote: >I've always wondered > if it might not be better to run hot lines down one side of the aircraft > and the ground bus down the other. Just a thought... This is not such a good idea for the following reason: If you separate the conductors such that the current is traveling in a loop by routing the wires as you suggest, the current will causes a magnetic field. This current could be substantial when you are charging your battery and would be huge when you are starting your engine. During a typical flight the magnetic field will be changing depending upon varying load conditions. Now, you and, more importantly, your wet compass are within the loop area. You will likely notice that your compass will swing around when you start up your electrical system. This ain't so good. Bob Nuckols advocates using *coaxial* conductors -- that is, a wire conductor surrounded by a copper tube for the ground return. This arrangement will make the loop area exceedingly small, since the center of the current paths are through the same geometric line (Is this clear as mud?). With this arrangement, the magnetic field of the wire will be exactly cancelled by the return currents in the tube. There are alternate approaches, such as separating the ground paths for each source/load and twisting a pair of wires together. Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ From: cdenk@ix.netcom.com Date: Wed, 10 Sep 1997 20:50:52 -0500 (CDT) Subject: Re: COZY: Electrical (fwd) On 09/10/97 13:56:58 you wrote: > >John Epplin wrote: > >>..... What if the >>vacumn line was used as the ground buss? I havn't really done any >>research concerning the resistence of 5052 al. tubing but I think it >>would probably suffice for several amps. Anybody have any reasons why >>this may be a bad idea? > >Yeah, aluminum's not as great a conductor as copper. However, you do >have a good idea here, which has been thought of and used before in a >slightly different incarnation. One of the suggestions in Bob Nuckolls' >book is to use copper plumbing tubing, crimped at both ends and with big >honking tabs soldered to them as the ground run in composite aircraft. >Copper is a much better conductor than aluminum. You could combine these >two ideas, use 1/2" copper tubing for your vacuum line (with appropriate >fittings on each end), solder tabs to the outside, and also use it as >your ground line. The copper tubing is also easier to bend to the right >shape, although that's not a really big deal. > >On the other hand, if all you're powering is the panel and strobes (the >battery is in the back), the 5052 might be OK. If the battery is in the >nose, then you really need something with a lot of current carrying >capacity, which would argue for the large diameter copper. > >-- >Marc J. Zeitlin Email: marcz@an.hp.com > > All electrical connections must be mechanical first, usually solder will cause a connection to weaken fatique wise, since it is stiffer. With the battery in the back, most of the load comes forward anyways, and the cable is still large. You want your main breaker where you can reach it - forward. From: TRCsmith@aol.com Date: Wed, 10 Sep 1997 22:14:45 -0400 (EDT) Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Rob You worry to much. not all aircraft wires are sheiled and the mag field you speek of will be to low to cause harm. That why all aircraft have a compass card in them..TURN ALL POWER ON, SWING AIRCRAFT!!! Tom From: "Rob Cherney" Date: Wed, 10 Sep 1997 23:01:07 -0400 Subject: Re: COZY: Use of Copper Tubing for a Ground Bus TRCsmith@aol.com wrote: > Rob > You worry to much. not all aircraft wires are sheiled and the mag field you > speek of will be to low to cause harm. That why all aircraft have a compass > card in them..TURN ALL POWER ON, SWING AIRCRAFT!!! Tom: Perhaps you are correct. You see, I have not had the opportunity to do it "wrong" and assess whether is good enough. Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ Date: Thu, 11 Sep 1997 08:12:00 +0200 From: Rego Burger Subject: RE: COZY: Electrical -R We have many conducting parts on our aeroplanes, I think they've just been ignored. e.g. 1.) Control tubes (under the arm rests ) 2.) The Engine mount. 3.) The Firewall. 4.) Fuel lines. Some advocate that these should be electrically bonded!? The problem comes in with them often having different materials.ie. Alu. and steel, we may accelerate corrosion by passing an electrical current through these, however where a continuous "line" of the same material is involved this would not be a problem. I just feel that copper should be used instead of aluminium, it's a better conductor. I have been toying with the idea of running copper "tape" along the longerons on each side. 1.) For ground and 2.) for the Positive. I get 1/2" x 1/16" "tape" or bar in rolls here and it should work fine for all the normal electrical needs. It might just be too light for a starter motor current. By having these two conducting "rails" along the entire span of the fuselage one will enable easy access to current. The only concern is the magnetic field may effect the compass a little. It will be important to paint the one red for easy recognition to avoid incorrect connections. The other place one can feed say a conduit/conductor is inside the heat duct, its hollow! Either of these routes I feel, is better than having spaghetti all over the show. The less connections the less chance of a malfunction. I wish to keep the wiring under my panel to a min. Thanks Steve Cambell for your Ideas. Rego Burger CZ4#139 RSA Date: Thu, 11 Sep 1997 08:51:07 +0200 From: Rego Burger Subject: COZY: Electrical Current and the Compass Just a short TRUE story! ( inspired by the conductor topics ) I noticed one during a run-up in a hired aeroplane that my compass moved up to ten degrees from idle to the run-up RPM! It would seem that a compass is sensitive and the extra power from a charging alternator or generator increases the magnetic variation. When mentioning this in the flying club Bar after a flight I was shot down as talking rubbish ( those were not the word used ) An instructor friend of mine was interested in my discovery and asked if I would demo it for him. I did and when he does a compass swing now it's with radio's on and at 2000 RPM. Remember most of our navigation work is done at cruise speeds with RPM's above 2000 RPM. The amount of change may be different for aircraft equipped with alternators vs. generators so each will have to investigate his own aeroplane and system. Food for thought. Rego Burger RSA From: TRCsmith@aol.com Date: Thu, 11 Sep 1997 07:23:34 -0400 (EDT) Subject: Re: COZY: Electrical (fwd) I use a 3/4 copper line in my Long, I run all wires that go to the engine compartment through it and it also serves as the ground from the batt. to starter. Tom From: SWrightFLY@aol.com Date: Thu, 11 Sep 1997 08:22:47 -0400 (EDT) Subject: Re: Re: COZY: Use of Copper Tubing for a Ground Bus In a message dated 9/11/97 7:53:05 AM, you wrote: << a wire conductor surrounded by a copper tube for the ground return. This arrangement will make the loop area exceedingly small, >> What wall thickness and diameter copper tube should be used? Steve Wright From: "mel" Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 08:44:09 -0400 wires dont short out in building conduits, but they dont vibrate as much as our planes do. breakers and fuses are there to protect our lives and projects, but why start out with a problem just waiting to happen? pipes carrying power are never a good solution, they make mag fields, and the corrosion rates are not predictable, not to mention what can happen to the devices they are delivering their fluid to weather the fluid be air, oil, water, gas, etc. the pipe now becomes an electroplating device of some type. weather material is to be deposited on your pipe or transferred from your pipe to another object is a matter of its polarity, current flow, pipe material, and medium being transferred in the pipe. now dont tell me its only AIR or VACUUM. remember their is moisture in that and after all we have acid rain dont we? these products WILL make their presence known. after all Murphy's law says "if it can happen it will" and always remember Murphy was an OPTIMIST!! norm (jafo) & monda (pilot) cozy IV #202 ---------- > From: MISTER@neesnet.com > To: cozy_builders@hpwarhw.an.hp.com; Jim Cullen > Subject: Re: COZY: Use of Copper Tubing for a Ground Bus > Date: Thursday, September 11, 1997 8:48 AM > > > Jim Cullen writes:"If any of the wires inside the tube are hot > (energized) and if, by rubbing against whatever they would happen to > abrade their insulation, you'd have a good opportunity for a short on > your hands inside the confines of the tube." > > That is what we have protective devices like fuses and breakers for. > Also, If there is a short circuit, I think I'd prefer to have it > confined in the copper tube rather than next to exposed structure, > > Bob Misterka N342RM > From: MISTER@neesnet.com Date: Thu, 11 Sep 97 07:48:10 EST Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Jim Cullen writes:"If any of the wires inside the tube are hot (energized) and if, by rubbing against whatever they would happen to abrade their insulation, you'd have a good opportunity for a short on your hands inside the confines of the tube." That is what we have protective devices like fuses and breakers for. Also, If there is a short circuit, I think I'd prefer to have it confined in the copper tube rather than next to exposed structure, Bob Misterka N342RM From: Kelly Russell Subject: RE: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 06:20:11 -0700 > pipes carrying power are never a good solution, they make mag fields, That's the beauty of having the hot wires inside the conductive ground conductor, the magnetic fields EXACTLY cancel each other. Therefore you greatly reduce the potential of any kind of interference or noise. > the corrosion rates are not predictable, not to mention what can happen to > the devices they are delivering their fluid to weather the fluid be air, > oil, water, gas, etc. > the pipe now becomes an electroplating device of some type. weather > material is to be deposited on your pipe or transferred from your pipe to > another object is a matter of its polarity, current flow, pipe material, > and medium being transferred in the pipe. > We're not talking about having any fluid etc. flowing in the conduit, only electrons. I'm a EE and do industrial instrumentation for a living, and thus have to live with this sort of stuff in noisy (electrically speaking) plant environments. Bob Nuckolls is right on target with his ideas put forth in the 'Aero Electric Connecton' (otherwise I doubt Burt would have let him do the electrical system on Voyager). There are many many details to a good electrical installation, way too many to cover here. Get Bob's book, it's well worth the investment. (See www.aeroelectric.com) Jim Hocut jhocut@mindspring.com (via borrowed e-mail account at work) From: MISTER@neesnet.com Date: Thu, 11 Sep 97 08:35:31 EST Subject: Re[2]: COZY: Use of Copper Tubing for a Ground Bus T SMith wries: " You worry to much. not all aircraft wires are sheiled and the mag field you > speek of will be to low to cause harm. That why all aircraft have a compass > card in them..TURN ALL POWER ON, SWING AIRCRAFT!!!" I must disagree! Compass correction cards are monuments to poor design and/or poor installation practice! Also, when your flying who needs another calculation to do or another thing to slip from an already overtaxed memory? I used Bob Nuckolls approach on my 3 place and I'm very pleased with the results. The noise performance is excellent. Also, my compass correction card has all zeroes on it. Bob Misterka N342RM From: Howard Calk Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 09:46:34 -0400 The main draw back of using copper tubing is the cost. The problem is you do not want to carry around more copper than you need. Its just extra weight. For a 1" diameter conduit (which is a practical size), it turns out this is a very thin walled copper tube. Here is how to calculate the wall thickness of the copper tubing you need for a 1" conduit: Obtain the diameter of number 2 AWG wire. Compute the area of this (pi times the radius squared). Compute the wall thickness by computing the area of the outside diameter (.7854 for 1") and the area of the inside diameter. Subtract the two and this will give you the cross sectional area of the tube wall. Pick a inside diameter which yields a result that is close to the cross sectional area of the #2 wire. Bob Nuchols will admit that this is an expensive way to go and says that a twisted pair (hot and ground) will give almost the same performance for a lot less money. I looked into this and did all of the calculations (sorry I don't know what I did with them). I found that: a) I had a hard time locating a source of thin wall copper tubing and; b) the thin walled tubing I did find _was_ very expensive. Howard Calk Long EZ builder -----Original Message----- From: SWrightFLY@aol.com [SMTP:SWrightFLY@aol.com] Sent: Thursday, September 11, 1997 8:23 AM To: cozy_builders@hpwarhw.an.hp.com; owner-cozy_builders@hpwarhw.an.hp.com Subject: Re: Re: COZY: Use of Copper Tubing for a Ground Bus In a message dated 9/11/97 7:53:05 AM, you wrote: << a wire conductor surrounded by a copper tube for the ground return. This arrangement will make the loop area exceedingly small, >> What wall thickness and diameter copper tube should be used? Steve Wright From: MISTER@neesnet.com Date: Thu, 11 Sep 97 08:47:08 EST Subject: Re[3]: COZY: Use of Copper Tubing for a Ground Bus Steve: I went to Home Depot and bought a coil of the 3/4" soft copper tubing they sell in the plumbing department. Get whatever diameter you need to hold the wires you'll put in it. Don't remember the wall thickness. Bob Misterka N342RM From: MISTER@neesnet.com Date: Thu, 11 Sep 97 08:59:47 EST Subject: Re[2]: COZY: Use of Copper Tubing for a Ground Bus Norm Doty writes: "breakers and fuses are there to protect our lives and projects, but why start out with a problem just waiting to happen?" I didn't and don't advocate using the copper tube for anything but a conduit for the wiring. I also don't agree that doing so is making a "problem just waiting to happen". By the way, wires do short out in building conduits and circuit breakers do keep the occurances from becoming a problem. Based on Bob Nuckoll's long experience in the industry, I'm more than willing to take my chances with his ideas. Bob Misterka N342RM From: Marc J. Zeitlin Subject: Re: COZY: Use of Copper Tubing for a Ground Bus (fwd) Date: Thu, 11 Sep 97 10:25:39 EDT Howard Calk wrote: >I found that: > > a) I had a hard time locating a source of thin wall copper tubing and; Not sure what you were looking for - any plumbing supply house or hardware store will carry copper tubing for house plumbing. > b) the thin walled tubing I did find _was_ very expensive. Also not sure why - It's only a couple of bucks for a 10 ft. section of 3/4" copper tubing. Howard gave some equations for calculating the area needed. I've got the Nuckolls book here in front of me, as well as the "Marks Handbook for M.E.'s". The area of 2 AWG wire is listed as 0.0521 in^2. To achieve this area in a 0.75" tube means that the wall thickness must be 0.025" or more. I believe than ALL copper tubing will be thicker than this, so the resistance in the tubing will be less than in the 2 AWG wire (which is already a small part of the overall resistance). Nuckolls does state "I recommend that wired grounds be considered in all cases except where the advantages of installing and maintaining wires in conduit justify the added labor". Chapter 5 of his book has a full explanation of why you might want to do one or the other, and how to go about it. -- Marc J. Zeitlin Email: marcz@an.hp.com From: "Craig R. Bowers" Subject: RE: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 08:34:29 -0700 Hi all; Bob has a good point, but... It all depends on where the circuit breaker or fuse is in the circuit relative to the point of the short. If the short occurs on the ground side of the protective device then, no problem. If the short occurs on the hot side of the protective device then, you have a real problem. Just a thought. :-) Craig R. Bowers I.T. Dept. Cerro Coso Community College cbowers@cc.cc.ca.us 760.384.6267 At home cbowers@truelink.net -----Original Message----- From: MISTER@neesnet.com [SMTP:MISTER@neesnet.com] Sent: Thursday, September 11, 1997 5:48 AM To: cozy_builders@hpwarhw.an.hp.com; Jim Cullen Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Jim Cullen writes:"If any of the wires inside the tube are hot (energized) and if, by rubbing against whatever they would happen to abrade their insulation, you'd have a good opportunity for a short on your hands inside the confines of the tube." That is what we have protective devices like fuses and breakers for. Also, If there is a short circuit, I think I'd prefer to have it confined in the copper tube rather than next to exposed structure, Bob Misterka N342RM From: Howard Calk Subject: RE: COZY: Use of Copper Tubing for a Ground Bus (fwd) Date: Thu, 11 Sep 1997 11:50:55 -0400 >Not sure what you were looking for - any plumbing supply house or >hardware store will carry copper tubing for house plumbing. >> b) the thin walled tubing I did find _was_ very expensive. >Also not sure why - It's only a couple of bucks for a 10 ft. section of >3/4" copper tubing. >Howard gave some equations for calculating the area needed. I've got the >Nuckolls book here in front of me, as well as the "Marks Handbook for >M.E.'s". The area of 2 AWG wire is listed as 0.0521 in^2. To achieve >this area in a 0.75" tube means that the wall thickness must be 0.025" or >more. I believe than ALL copper tubing will be thicker than this, so >the resistance in the tubing will be less than in the 2 AWG wire (which >is already a small part of the overall resistance). Yes, all copper tubing from the local building supply is much thicker than needed. That is my point, while there is no problem handling the electrical loads you will be carrying around a lot of unnecessary weight. How much does 10 to 12 ft. of 1" copper pipe weigh? Why carry extra weight when you can get close to the same performance from other methods? Also, I don't think that .75" copper pipe is big enough for a conduit. If you can't run all the wires you need down the conduit why not just use the twisted wire method? I spent a good bit of time talking to Bob Nuckolls and he recommends another alternative in his book as being more cost effective. Howard From: "Johnson, Phillip" Subject: COZY: Electrical Date: Thu, 11 Sep 1997 15:58:50 -0400 John Epplin wrote: >..... What if the >vacuum line was used as the ground buss? I haven't really done any >research concerning the resistance of 5052 al. tubing but I think it >would probably suffice for several amps. Anybody have any reasons why >this may be a bad idea? Marc Z beat me to the copper solution. 5052 may have problems long term. It is very difficult to achieve a good connection. In time corrosion will set in and grounding problems will almost certainly occur. Phillip Johnson Date: Thu, 11 Sep 1997 13:40:48 -0700 From: "LCDR James D. Newman" Organization: INFINITY Aerospace Subject: COZY: RE: Use of Copper Tubing for a Ground Bus Hi All, >Yes, all copper tubing from the local building supply is much thicker than needed. That is my point, while there is no problem handling the electrical loads you will be carrying around a lot of unnecessary weight. How much does 10 to 12 ft. of 1" copper pipe weigh? Why carry extra weight when you can get close to the same performance from other methods?< It seems the discussions have lost partial sight of the 'special purpose' of why to use 2 - 1" OD thin wall copper tubes from the nose to the tail in the fuselage floor (see subject line) - the copper tubes not only can provide a conduit to house the wires (among the other benefits noted), it replaces the need to, also, run the heavy #2 cables from the battery in the nose pos & neg to the engine, therefore saving weight. But, if the battery will stay in the back, obviously there is no need to run heavy cooper tubing to the nose when a plastic tube can be used as a conduit and the other methods mentioned of handling the wires is all you need. HTH. Infinity's Forever, JD From: Marc J. Zeitlin Subject: COZY: RE: Use of Copper Tubing for a Ground Bus (fwd) Date: Thu, 11 Sep 97 17:05:23 EDT Jim Newman wrote: >........ - the copper tubes not >only can provide a conduit to house the wires (among the other benefits >noted), it replaces the need to, also, run the heavy #2 cables from the >battery in the nose pos & neg to the engine, therefore saving weight. Not quite. Howard's point was that the copper tube will weigh MORE than the #2 AWG ground wire would have and he's right (because you can't get real thin wall copper tubing cheaply, although the plumbing stuff is cheap as dirt), by about a pound or so. The question then boils down to whether the electromagnetic, routing, and possible other advantages of the copper tube outway the extra weight and work. That's a personal choice, obviously. If, going back to John Epplin's original question, you used a copper tube as the vacuum line AND as the ground line, then you're probably even on the weight, since copper weighs more than the aluminum would have but you've eliminated the #2 AWG ground wire. In this case, you could wrap the #2 AWG positive wire around the ground/vac tube for Mag field elimination. Is this horse dead yet? :-). -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Thu, 11 Sep 1997 22:08:31 -0400 From: "Carl R. Denk" Subject: Re: COZY: Use of Copper Tubing for a Ground Bus MISTER@neesnet.com wrote: > > T SMith wries: " You worry to much. not all aircraft wires are sheiled > and the mag field you > speek of will be to low to cause harm. That > why all aircraft have a compass > card in them..TURN ALL POWER ON, > SWING AIRCRAFT!!!" > > > I must disagree! Compass correction cards are monuments to poor > design and/or poor installation practice! Also, when your flying > who needs another calculation to do or another thing to slip from an > already overtaxed memory? > > I used Bob Nuckolls approach on my 3 place and I'm very pleased with > the results. The noise performance is excellent. Also, my compass > correction card has all zeroes on it. > > > Bob Misterka N342RM > Mount the compass overhead on a 1/2" alum. tube with all non-magmetic hardware, and a small rubber bumper against plexiglass bubble. Frees up panel space, and not affected by electrical fields. From: "mel" Subject: Re: COZY: Use of Copper Tubing for a Ground Bus Date: Thu, 11 Sep 1997 22:44:48 -0400 all thats been said is true but the only wires that usually short out in conduit in industry usually started out with a problem to begin with ie. vibration, sliced during pulling, not proper radius in boxes or devices, wire not correctly sized, not proper type of insulation for job or environment, fused or breakered incorrectly, conduit not properly prepared (rough edges after cutting), incorrect or no bushings on threads of fittings. and a whole bunch of other things that i cant remember at this time. this type of wiring is useable in an airplane and if done CORRECTLY can and would be a very good wiring system. i just dont think it suits our home built philosophy of the K.I.S.S. principle, standard wiring (mil spec type) and good common sense will give you a very good wiring system that should be trouble free for a very long time norm & monda cozy IV #202 ---------- > From: Carl R. Denk > To: MISTER@neesnet.com > Cc: cozy_builders@hpwarhw.an.hp.com; jimculle@vegasnet.net; norm.doty@worldnet.att.net > Subject: Re: COZY: Use of Copper Tubing for a Ground Bus > Date: Thursday, September 11, 1997 10:10 PM > > MISTER@neesnet.com wrote: > > > > Norm Doty writes: "breakers and fuses are there to protect our lives > > and projects, but why start out with a problem just waiting to > > happen?" > > > > I didn't and don't advocate using the copper tube for anything but a > > conduit for the wiring. I also don't agree that doing so is making a > > "problem just waiting to happen". By the way, wires do short out in > > building conduits and circuit breakers do keep the occurances from > > becoming a problem. Based on Bob Nuckoll's long experience in the > > industry, I'm more than willing to take my chances with his ideas. > > > > Bob Misterka N342RM > I agree, copper tube is heavy, probably twice the weight of alum. Stick > with the tried and true. Date: Fri, 12 Sep 1997 07:30:20 -0700 From: Jim Cullen Subject: COZY: Re: Use of Copper Tubing for a Ground Bus In a private conversation on the subject, J.D. from Infinity Aerospace mentioned something that I had forgotten. While a lot of the copper tubing on the market is manufactured by an extrusion process (so-called seamless tubing) other forms of tubing are manufactured by rolling flat stock around a mandrel and then welding a seam along the length of the tube. Seamed tubing has, as an inherent result of its manufacturing process, a rough joint on the inside of the tube. Combine that with the vibration of the aircraft and I can't help but wonder just how good an idea this Copper Tubing/Ground Bus idea is. Now I have a history in this group for gettiing spammed for pointing out non-existant problems -- sigh -- so you decide for yourself if this is a problem or not. I'll just plant the idea in your brain. You decide if it has any merit. Jim P.S. to Carl Denk: You have no idea as to how long I been have trying to figure out where to mount my damn magnetic compass. My panel is already full and I never liked the idea of putting it dead center on the panel cover. Your idea about mounting it on an aluminum tube -- overhead -- against the top of the canopy -- is a wonderful solution to my problem. Are there any vibration problems (compass bouncing against the canopy -- even with a rubber bumper) in doing this? Have you ever seen such an installation in a flying aircraft? If so, I'd love to talk to the builder, to see whether or not he likes the installation... Jim by InfoAve.Net (PMDF V5.1-8 #23426) with SMTP id <01INKBF8V2SA91NRK8@InfoAve.Net> for cozy_builders@hpwarhw.an.hp.com; Fri, 12 Sep 1997 17:57:18 EDT Date: Fri, 12 Sep 1997 17:55:27 -0400 From: Jeff S Russell Subject: COZY: Re: compass mount Organization: AEROCAD INC. Jim Cullen wrote: > Your idea about mounting it on an aluminum tube -- overhead -- > against the top of the canopy -- is a wonderful solution to my problem. > Are there any vibration problems (compass bouncing against the canopy -- > even with a rubber bumper) in doing this? Have you ever seen such an > installation in a flying aircraft? If so, I'd love to talk to the builder, > to see whether or not he likes the installation... Jim, I have ours mounted overhead in the top of the canopy cover because we do not have glass totaly overhead in our canopy. Looks like a rap-a-round windshield but we still used a full bubble canopy like the MKIV shape. Unless you look up for it you do not know that it's there. Works great and no electricial problems. You want them to (shake) with a rubber bumper or the compass won't turn and as long as it won't touch the glass it won't shake to much. hope that helps -- Jeff Russell/AeroCad Inc. E-mail: Jeff@aerocad.com Phone/ fax (call first): 910-961-2238 AeroCad: http://www.aerocad.com Composite workshop info: http://www.Sportair.com From: cdenk@ix.netcom.com Date: Fri, 12 Sep 1997 18:48:17 -0500 (CDT) Subject: COZY: Re: High mounted compass On my Cosy Classic, I have a high mounted compass. I have my GPS (bar of soap style) mounted on the top of the turtleback, 4" aft of the plexiglass (including the hidden part). I take advantage of this reinforced plus access to the top for screw heads. Under I have a say 3" x 3" x .043" aluminum welded to a piece of 1/2" aluminum tubing. THe tubing comes forward about 18", and then another piece of .035" alum. bent 90 degrees down, and avex riveted to the tube. THe vertical becomes a flange cut to fit the top of the compass. The compass is the style with rounded forward face, no bottom mounting ears, and illuminated. The wire goes thru the tube. The forward plate has a 1/2" o.d. rubber bumper foot (the type that squeezes thru a ~ 1/4" hole. THe tube is bent to follow the curvature of the plexiglass plus some spring to hold the bumper against the plexiglass. I have a fiberglass housing to cover the bottom of the antenna and aft end of tube connections. The housing has a tight fitting slot forward for the tube that gives upward force to the tube. It does not viberate, but you must be accurate with mounting the compass face at right angles to the airframe centerline. From: SMilesCozy@aol.com Date: Fri, 12 Sep 1997 22:51:20 -0400 (EDT) Subject: Re: COZY: Electrical In a message dated 97-09-10 14:16:57 EDT, you write: > I believe that it is possible, but not > easy, to make reliable electrical contacts to Al. > Steve > > ************************************************ > Stephen A. Campbell, Associate Professor, ECE > University of Minnesota Most modern electrical distribution equipment (panelboards, lighting panels), have aluminum busses. They make a comercially available paste (available at your local electrical supply house), that comes under several names, ( "no-alox," & "contax," are a couple off the top of my head), that inhibit oxidization / corrosion of the connections. To take this discussion on a tangent, why not embed properly sized aluminum busses under the glass, from front by the panel to the rear by the firewall, much, much, lighter than equivelant (for the amps) copper. And if you needed power anywhere along the length of the bus, you would just have to drill into the buss, tap the hole, and install a screw. Wire this to an appropriately sized breaker, and vola' instant electic, where you need it. Steve Miles From: SMilesCozy@aol.com Date: Fri, 12 Sep 1997 23:37:25 -0400 (EDT) Subject: Re: COZY: Electrical -R In a message dated 97-09-11 02:34:20 EDT, you write: > I have been toying with the idea of running copper "tape" along the > longerons on each side. 1.) For ground and 2.) for the Positive. > I get 1/2" x 1/16" "tape" or bar in rolls here and it should work fine > for all the normal electrical needs. It might just be too light for a > starter motor current. > > Rego Rego, standard procedure, is to calculate the total of all loads expected, and multiply by 1.25 as a safety factor. ie: total load expected at instrument panel = 40 amps, 40 X 1.25 = 50 amps. For a known, possibly continuous load of 40 amps, the bus or wiring should be capable of carrying 50 amps. As far as the size of the "tape" or bar stock needed, there are many references available that have tables for properly sizing wire, or busses ("tape") based on cross sectional area. 50 amps would require a 6awg copper conductor, on a 4 awg AL conductor, I don't know if 1/2" X 1/16" would be adequate or not, for that matter, I'm not sure if the tubing would have the required cross sectional area required either, maybe skin effect would take care of it in the case of the tubing. In the US the National Electric Code contains all of this and is a rather inexpensive reference if you do any wiring around the home. Sincerely, Steve Miles From: "Rob Cherney" Date: Sat, 13 Sep 1997 15:41:43 -0400 Subject: Re: COZY: Electrical -R SMilesCozy@aol.com wrote: >....... maybe skin effect would > take care of it in the case of the tubing. Skin effect reduces the effective cross-sectional area as signal frequency increases. It is not a factor for our electrical systems. Rob- +--------------------------------------------------------+ |Robert Cherney Home Phone: (410)465-5598 | |Ellicott City, Maryland e-mail: cherney@clark.net | +--------------------------------------------------------+ From: SMilesCozy@aol.com Date: Sun, 14 Sep 1997 01:37:27 -0400 (EDT) Subject: Re: COZY: Electrical (aluminum causes fires?) In a message dated 97-09-13 20:04:30 EDT, you write: > If you want to find the real practical facts on trying to connect to > Aluminum, I suggest talking to your local electrical building inspector, and > fire department, I think they will have some horror stories. Post what they > say. If you look inside the electric service of "almost" any new home with a 200 amp electric service, you will find that the entrance cable is 4-O 3 conductor ALUMINUM Service Entrance cable, that passes through a meter base that houses 3 ALUMINUM pairs of clips to hold the meter, to an inside panelboard with an ALUMINUM busbar, with a #4 ALUMINUM grounding conductor to the water pipe and a solid #6 copper grounding conductor to the outside 8' ground rod. (if required) ("solid" and "copper" due to direct contact with the moist soil and the corrosion potential) EVERY ALUMINUM connection in this arrangment MUST be coated with an oxide inhibiting compound or paste. Most branch circuit conductors used residentially that are over 100 amps (#2 AL) are also ALUMINUM cable, the reason for this is pure economics. Copper conductors usually don't show up until #6 or smaller. Why? Because with smaller sizes the price difference diminishes and the number of splices and connections (possible points of arcing, thermal expansion, and failure) go up. Making copper the best alternative for smaller branch circuits. > And most of the connections that went bad were in the nice dry inside > of a building with no vibration. MOST of the failures that I am aware of were related to the "wiring devices" (switches, recepticles, circuit breakers, etc.) failing. The original "aluminum rated" wiring devices, (AL-CU), were found to have a potentially heat generating, fire causing, compatability problem with aluminum wiring. Modern, properly "rated" wiring devices, (CO-ALR), work just fine on AL wiring. (at least no failures to date as far as I know) My personal home was built in the early 70's. The entire home is in ALUMINUM wiring. Since I am an electician, I replaced all the devices in the home with CO-ALR rated devices. I have absolutely no problem with my family sleeping here. > Incidently I don't append my name with the P.E. (Professional Engineer), because > I don't feel I have sufficient expertice to be an expert witness in court. I AM a licenced electrical contractor, and put my butt on the line every day. IMHO, like many other things, when PROPER procedures are used, AL is an economical alternative to CU, both in $ and #, for some higher amperage electrical applications. > The prudent thing to do is stick with the proven way! As far as "the proven way" with wiring procedures is concerned, any electricians handbook, or the National Electric Code handbook, would be a good place to start. > Be careful > what people on the net post, most of my time with email I end up cautioning > people on questionable at best practices. I agree with this completely. By defending aluminum as a conductor, I don't want anyone to think that I would recomend wiring your entire aircraft in AL wiring, besides you probably can't find it in smaller sizes. All I was saying is that it "could", FWIW, make a light, well insulated, built in, easily accessible, main bus, to get power from the back to the front or versa-vise. All of my branch circuits will be in aircraft grade, twisted pair, stranded copper, of the appropriate gauge, with properly sized overcurrent protection. But my main bus? hmmmmmmmm. Sincerely, Steve Miles Date: Mon, 15 Sep 1997 13:01:37 -0700 (PDT) From: Jerry Kennel Subject: COZY: Cozy: Suction Hose What is the best hose to use for the vacuum system on the Cozy? Where can I get this hose and fittings? Thanks for the help!! Jerry Kennel Date: Mon, 06 Oct 1997 09:49:53 From: "Robert L. Nuckolls, III" Subject: COZY: "A Switch is a Switch or is it?" I've submitted this article to Sport Aviation and would like to give them first North American rights for print publication. I've had some requests for permission to reprint in various newsletters, etc. As soon as the article appears in Sport Aviation, newsletter editors may feel free to reprint as they see fit. The topic came up on a list-server thread and I like to give my net-linked compadres a look at it, just hold off on reprinting for a little while. ============================================================ Switch Ratings - What Does it all Mean? Just catching up on piles of snail-mail and e-mail that tends to build up while were flitting from fly-in to seminar. Picked up a copy of the Oct 97 issue of Van's Air Force and read an article on switch selection that makes some good points but arrives at the wrong conclusion. The author was privileged to observe some work done at UL Laboratories on switches and expressed some concern for builder naivety with respect to AC versus DC ratings. He correctly cites an increased difficulty for BREAKING a DC circuit versus an AC circuit . . . particularly when inductive loads are involved. Quoting from the article: "Typical of this is the roller and bar micro switches made by MICRO(switch) Corporation. Rated at 10 amps for 125/250 volt AC, the same switch can only carry 0.15 amps at 250 volts DC! The voltage stayed the same!" The statement is true but not relevant to our task. We're not building 250-volt airplanes, we build 14 and a few 28-volt airplanes. Check out this data table plagiarized from the same Microswitch catalog . . . Elec. 28 VDC 115 VDC 250 VDC 115 VAC 230 VAC Code ------------ ------- ------- -------------- ------- Rating Ind Res Lamp Res Res Ind Res Lamp Res 1 15 20 5 .75 .5 10 15 3 6 2 10 15 4 .75 .5 7 15 2 6 3 15 20 7 .75 .5 15 15 4 6 4 10 18 5 .75 .5 8 11 2 6 5 12 20 5 .75 .5 15 15 4 6 6 10 18 4 .75 .5 8 11 2 6 As one picks from the various switch products in the catalog, an "electrical code rating" is quoted for each device . . . the chart above states the ratings for each code. When one buys a toggle switch from Microswitch . . . the choices above are all inclusive. The charge cites a variety of conditions for applying switches. Various combinations of AC or DC voltage along with loads can have a profound effect on switch life. Inductive load do call for some derating but look at the column for lamp loads . . . it calls for the greatest derating . . on the order of 75%! I'll call your attention to the 250 VDC column for ALL switches. Note that none are rated at more than 0.5 amps in spite of the fact that the same switches are good for 6 amps at 250 VAC and MANY more amps at lower voltages. Quoting again from the article: "Those of you who can still remember the old Kettering coil ignition systems will recall that when the condenser in the distributor went bad, the points generally turned blue and melted down in a few minutes. . . . " The cited capacitor was to slow the rate-of-rise for voltage across relatively slow moving, cam driven switch contacts. If an arc were allowed to form between the opening points, energy intended to spark combustible mixtures in a cylinder would be used up at the points instead . . . the most notable result of bad "condenser" was the car ran very badly if at all . . . the points were indeed subject to more electrical stress but seldom for very long . . . this situation demanded timely repairs. Switches of choice for airplane panels are not cam driven. Toggles use spring loaded, over-center mechanisms that provide higher contact spreading velocities. Going on with the article . . . "Cockpit switches don't have benefit of the condensers to absorb the electrical inertia present in a DC circuit and as a result, the gap temperatures get hot enough to weld contacts. That includes AC rated switches, even those made with exotic high temperature alloys." The Kettering ignition example is an excellent way to illustrate "inductive" circuits. However, there are few such circuits in an airplane. Most notable of these are battery and starter contactor coils. We don't put "condensers" on these systems but we do install "catch diodes" or MOVs (metal oxide varistor) to protect switch contacts. This has been standard practice in airplanes for 30+ years (just worked on my kid's '72 Chevy truck today and saw a 1N4001 diode crimped into the connector for the air-conditioning compressor clutch). The article also overlooks the differences in physics between burning contacts and welding them. Most damage to switches is done during the BREAKING of a circuit where an arc forms in the widening gap. Depending on contact spreading velocity -AND- thermal mass of the contacts, this can be the most stressful task for switching. However, this is when the contacts are getting FARTHER apart . . hardly the scenario for welding. The physics for CLOSING a circuit are different. Here, potentially high inrush currents are impressed across contacts that may have small hills and valleys erroded in them from previous switch openings. These little hills become potential welding material when the large inrush current is forced to flow through a small cross section of material. This can happen to ANY switch with either DC or AC. By-in-large, switched circuits in airplanes are resistive but let's look again at the purloined data from Microswitch. In nearly all cases (except Code 5) DC ratings at 28 VDC for the switches cited are BETTER than the ratings for 115 VAC! (????) As a general rule of thumb, I've told builders that the 115 VAC rating is directly translatable to 14 VDC applications. I'll offer the chart above in support of this advice. The article continues . . . "What often happened during UL testing was that the points welded shut, making it impossible to open the circuit." Sure, let me pick the test parameters and I can probably weld about any switch shut. Keep in mind that UL has to test for EVERY possible safety contingency in product design and utilization. We design and build failure tolerant designs and select electrical devices that perform in narrowly defined settings. In years of fiddling with airplanes, I've never seen a manual switch weld shut. I've seen them corrode open, I've seen over-center springs rust out, I've see wires break off the back, etc. But never a welding. Now, contactors weld . . . with some frequency . . . but that's another topic. Stresses necessary weld switch contats in the lab simply don't exist in airplanes. The heaviest currents handled by panel switches are landing/ taxi lights (which have their own special inrush values - see "lamp" ratings in table above), and pitot heat. For most 14 volt airplanes this is about 8 amps. Everything else drops rapidly from there. I can also tell you that switching an 8-amp landing light with a 4-amp "lamp" rated switch is not an automatic formula for welding. The overload will indeed reduce the life of the switch. However, let us suppose the switch was originally rated for 10,000 cycles (a low estimate) and the reduction was to 10% of rated life (also very low) . . . How long will it take you to put 1000 cycles on your landing light switch? Further, like the addition of MOVs or catch diodes for breaking inductive circuits, there are simple devices (inrush limiters) that may be used in high current lamp circuits to relive sresses on the switch to the extend that stresses are no greater than purely resistive loading. In a nutshell, 125 VAC ratings equate favorably and conservatively to 14 VDC ratings - as long as the switch has a healthy "snap" action . . . all toggle switches and most rocker switches do. Just because the numbers stamped on the side of the switch don't MENTION a DC capability doesn't mean that the switch doesn't have one. Manufacturers are unable to put ALL of the information from the chart onto the side of every product, the lettering would be too small to read! The article also alluded to a 3X increase in the price of switches to get "DC rated" devices and postulated that delta-dollars for 10 switches would be $35. Hmmmmmm . . . this means that the ORIGINAL switches being compared cost about $1.75 each! I can't think of any $1.75 switch I would consider for use on an airplane and it has nothing to do with AC/DC ratings! The switches we stock sell for $5.00 in a single-pole device and carry no markings for DC ratings. They are rated at 7 amps or better at 115 AC and will work just fine in virtually every slot on an airplane panel. No matter where you choose to purchase switches, know that concerns raised by the original article are unsupported either by experience or failure mode physics. Happy switching. Bob Nuckolls AeroElectric Connection www.aeroelectric.com Date: Tue, 07 Oct 1997 08:58:31 From: "Robert L. Nuckolls, III" Subject: COZY: Battery installation >The corrosive resitant paint you were discussing, is called "Black Bituminous >Paint" and is impregnated with black bituminous coal powder. Special paints of several formulations have been around for years and used in one form or another on airplanes to protect surrounding materials from the effects of lead-acid battery fumes and leaks. . . > >Batteries being what they are, an electrical storage device, as well as an >electrical "accumulator" of sorts, all have some sort of electro chemical >substance in them, that makes them work. The new "gelcell" batteries, >regardless of their claims, still have corrosive chemicals in them, and if >they should crack, and or leak, I think they might cause some problems. >(Ergo, they bear watching through close and reasonably frequent inspection.) > Actually, true "gel cells" are getting hard to find. There are some deep cycle versions popular with electric wheelchair manufacturers but the new sealed batteries for airplanes are liquid water-acid technologies. For some background please check out "The Batteries are Comming, the Batteries are Comming" in Sport Aviation, August 1993, and a short piece at which I am going to expand by tacking this thread on the end of it. >These "sealed" and "maintenance free" batteries, as a by product of the >chemical reactions taking place inside, probably still have to create some >form of hydrogen gassing. I have always wondered what they do with that >hydrogen gas. It has to go somewhere. Where does it go? Correct . . . but true to their name "recombinant gas" they contain and recombine evolved gases back into water. This can happen because all the liquid is TOTALLY contained in thin, fiberglas mats that are about 80% saturated . . drive a nail into one of these batteries and you get NOTHING out . . . the battery will continue to function until it dries out. The cells have pressure relief valves that will vent if the battery is abused. But even when horribly pressed, the battery simply goes "pffffsssst" and it's all over. Their liquid filled ancestors were wont to spew steaming jets of acid and water all over everything before going down for the count. > >At the risk of sounding crass, an excellent source for information that might >foster understanding of such things, are the books used by prospective >aircraft mechanics (technicians) who are going through A&P school. They are >divided up into pretty clear (though relatively general) subject areas, which >might lend to clearer understanding. I wish this were true . . . of the schools I've visited and books I've looked at, most a/p mechnics ciriculums have more to do with passing FAA multiple guess exams than on how to fix airplanes. If anyone finds a good book out there, please send me the particulars. I'd like to buy one to look at. > >The new Gel Cell batteries may not be mentioned in the books, but they still >have a lot of useful information concerning lead acids, and ni-cads. > These days, I wouldn't put a liquid lead acid -OR- a ni-cad in a small airplane . . . they need battery boxes and have too many other hazards associated with them. The RG battery didn't become a popular consumer item until computers in offices began to demand clean, fume free, totally benign sources of stored energy for un-interruptable power supplies . . . You think you have a problem with getting proper paint for your battery box, wait until you spill acid on the carpet of some lawyer's office!!!! The RG battery doesn't need a box . . in fact, is safer just simply strapped down to an open tray. Make sure the attach mechanisms are good for 10g's and use rubber booties over the exposed terminals. Simple, light, clean. NOW . . . if you'd truly wish for the battery to be the most reliable source of power in the airplane, either (1) do capacity checks every 6 months and discard when down to 50% or less or (2) simply replace the battery every two years. Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= http://www.aeroelectric.com From: Gunrider@aol.com Date: Wed, 8 Oct 1997 10:51:54 -0400 (EDT) Subject: COZY: RIGHT SIDE CONDUIT? Being that I weigh much more than my wife (even when pregnant). I have been thinking of moving what I can to her side. Can the conduit be easily moved to the right side? I' m probably going to use the thin-walled copper tubing. Hugh Farrior puttin' in the control system From: Marc J. Zeitlin Subject: Re: COZY: RIGHT SIDE CONDUIT? Date: Wed, 8 Oct 97 11:10:05 EDT Hugh Farrior wrote; >Being that I weigh much more than my wife (even when pregnant).... I'd think that when you were pregnant, Hugh, you'd weigh LOADS more than your wife :-). > Can the conduit be easily moved to the right side? I' m probably going to >use the thin-walled copper tubing. What conduit are we referring to here? Vacuum, electrical? I don't think that there's any specification on which side either one have to go on; there's an electrical chase on both sides of the plane. Putting the battery way over on one side of the main spar would have a lot more affect, I think. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Thu, 09 Oct 1997 09:43:27 From: "Robert L. Nuckolls, III" Subject: COZY: The great breaker debate . . . I'll invite subscribers to this list to check out a new piece I've posted Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= http://www.aeroelectric.com Date: Thu, 09 Oct 1997 22:35:51 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Ready to saddle up . . . > >One suggestion for the postings relating to your web site -- if the three >samples you included in this posting are an example of your plan, they are a >bit cryptic for me although I can figure out what they might be about. If >you could add a short paragraph, or sentence, better describing the nature of >the content of posting, it might give a better idea as to whether it is >worthwhile visiting or not. Excellent point! Here's an annotated repost . . . > > > An annotated "wing and a prayer" story . . . "It was a dark and stormy night and all of a sudden, the main breaker blew leaving me in the dark." I wish it were really humerous and in this case the story does have a happy ending . . . BUT . . . it should not have happened in the first place. > > > Illustrated instructions on modifying the "Piper style" ground power jack sold by Aircraft Spruce for use on your airplane. Schematics and step by step instructions. > > > "The switch says '7A @ 125 VAC', can I use it on my airplane? Where do I buy DC rated switches?" Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= Date: Thu, 09 Oct 1997 23:17:03 From: "Robert L. Nuckolls, III" Subject: COZY: RE: The great breaker debate . . .Yeahbut..... >Bob, > >Your web page on the use of fuses in place of breakers is right, I think. Maybe. > >With your wide experience you tell to use fuses but we amateurs, with the wisdom >gained from looking at existing panels say "yeah, Bob, but..." Here are a few >yabuts. > >"It isn't done this way, breakers are the standard way." > Who's "standard" . . . where is is written? FAR21, 25, 43 all speak to the use and maintenance of both fuses and breakers. How did breakers become a "standard". They certainly became a custom as people found out how BAD the little fuse holders are with the caps that drop on the floor and roll all the way back to the baggage compartment. Breakers became a convenience. No place in the FARs does it say that ANY fuses or breakers have to be located in reach of the pilot. They DO say that fuses in reach of any crew that powers "flight critical" circuits must be backed up with 50% spares. So tell me what systems on your proposed airplane are "flight critical" meaning that failure of the device presents an immediate hazard to flight? >"I can't risk the lives of my loved ones on something different." > Explain the risk. Paint the scenario where reseting a breaker in flight is going to bring some absolutely essential piece of equipment back on line. >"It is harder to replace a fuse in flight than to reset a breaker." > > You betcha . . . that's why I don't bother to put them anywhere I might even be tempted to fiddle with them in the air. Be a pilot in the air and save being a mechanic until on the ground. >"We should not use anything that is used on automobiles until it is proven on >airplanes" You got it backwards. The stuff on current airplanes was certified in 1940- 1970 with precious few changes since then. Take a walk through the Service Difficulty Reports on the net and see how often a "certified" piece of equipment fails. Of course it can be "overhauled" and yellow-tagged and put right back on an airplane . . . it's the same piece of 1960's technology that came off in the first place . . . you have any confidence in that? On the other hand, how often do you have problems with similar gizmos in your car? The environment under the hood of a modern automobile is just as punishing as under the cowl of an airplane. There's temperature cycles, splash, sand, dust, ozone, oil vapors . . . you name it. For myself, I've replaced one alternator on one of 7 cars owned over the past 12 years with a cumulative total of more than 4,000 hours operating time . . . As I write these words, B&C is doing a booming business in STANDBY alternators out of his booth at the American Bonanza Society show here in Wichita. He just told me on the phone about how often people have alternator troubles in their airplanes. If I owned a $40,000 automobile and had these kinds of troubles, I'd be all over the dealer. Yet people fly around in $250,000 airplanes and put up with the most rediculous problems because "fixing" the problem is too expensive . . . and besides, the current system is "certified." The majority of alternators, starters, fuel injection systems, ignition systems on cars go to the junk yard still working after 100,000+ miles of service. Airplane products and designs are "carved in stone" while automobiles continue to evolve and become better and better values every year. I'd put any modern automobile part on my airplane before I'd opt for a part out of a salvaged C-172 . . . even the new ones right off the assembly line. > >"What if I later want to sell my airplane - who'd buy it with fuses?" > Somebody who understands why you elected to use fuses instead of breakers and why they're out of reach just like on your car. Check the threads and articles out on our website for more info . . . > >"A few fuses aren't nearly as impressive as a panel full of switches." > Now there is an EXCELLENT reason for going to breakers. I had a client a few years ago hire me to do a wirebook for his proposed BD-10J project. It was a design goal to make this airplane "look as military as possible". We ended up with 65+ breakers in the airplane for a total of $1300.00. Personally, I'd rather use that money -AND- panel space for something really useful like a second GPS receiver or perhaps a CD player. Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= Date: Fri, 10 Oct 1997 08:59:32 From: "Robert L. Nuckolls, III" Subject: COZY: Re: Ammeter Question At 01:56 AM 10/10/97 -0400, you wrote: >Bob: Have seen several of your articles, and have never failed to learn >quite a bit from each one. . . . Thank you. I'm pleased to be helpful. > . . . . . I have a T-6G, 28v system, generator with OLD >voltage reg. The ammeter is a generator-load meter, showing only positive >amps as the load increases, but not negative amps as the load increases on >the battery. The scale of the meter is wrong, in my opinion. Rarely draw >more than 30 amps, yet the meter goes to 150 amps. At normal draw of 5-10 >amps, the needle barely moves off of zero. Obviously, a poor selection of instrumentation. >I recently bought a combination voltmeter/ammeter.......the type that reads >amps until you push and hold a button in order to read volts. Max scale >is 30 amps. Both the installed meter and the new meter have an external >shunt. The existing shunt will carry up to 150 amps, with "X" millivolts >providing full-scale needle deflection. ( I forget what "X" is) >The new volt/ammeter came with a shunt that is rated at only 30 amps, with >the same "X" millivolts being full-scale (in this case 30 amps) deflection. This is good stuff . . and why I'm forwarding this letter to some list servers I subscribe to. A standard within the instrumentation world is to design remote shunt ammeters such that 50 millivolts on the instrument's terminals will cause it to read full scale. That scale could be 1 amp or 1,000 amps . . . it matters not. The remote shunt is simply a precision power resistor designed to drop 50 millivolts across its terminals as it passes design current levels. Hence, take about any remote shunt style ammeter and it will read FULL SCALE at whatever current the SHUNT is calibrated, irrespective of what the instrument's scaleplate sez. >My question is: How can I properly install an ammeter with a scale that >will let me read the meter, say 0-30 or 0-50 amps? Do I have to change the >Shunt? Yes . . . install your new shunt in place of the old one, wire in the new instrumenet across the shunt (use 5 amp in-line fuses in each lead coming from the shunt . . . the fuses mount as close to the shunt a practical). >If so, does the rating of the shunt have to approximate the rating >of the generator? Sure. The original situation you cited illustrated how impractical it was to monitor the output of a 30 amp machine with a 150 amp instrument. For alternator load meters, I don't calibrate them in AMPS, just percent of load. Then, I'll keep a selection of shunts around for the popular alternator sizes. The pilot's real interest is in how much of the alternator's capacity is being taxed. Hence, a meter that reads in percentage of some shunt value fills the bill. The the builder wants to but in a bigger alternator later, he just changes the shunt, the SAME instrument stays in place on the panel. Nifty huh???? >Does the shunt have to match the ammeter? Yes . . . the SCALE PLATE has to have the same full scale reading as the ampere rating on the shunt. >Thank you in advance for any advice you might have. And if time doesn't >permit you to answer these questions, I fully understand. You're most welcome and than you for the question. We'll make time. The institutionalized aviation community has held their "black art" very close to the chest. While ordinary citizens are building their own byte-thrashing computers from mail-order parts, citizens who own airplanes are not expected to know or even want to know how they work. It's time we stopped that and started sharing the knowledge. That's what these list-servers and our business is all about. >Peter C. Hunt > >"HUNTER" >Capt. USN, ret. Ex Fighter Pilot, A&P, T-6 Owner/Operator. > > > Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= Date: Fri, 10 Oct 1997 10:38:23 From: "Robert L. Nuckolls, III" Subject: COZY: Re: The great breaker debate . . .Yeahbut..... <19971009.204841.4863.0.GASobek@juno.com> > I don't want to start another great debate over the fuse Vs Breaker >concept, but I have to take exception to your example. > > First of all, it would appear from your statements that you're talking >about UNMANNED spacecraft. I to beleive that fuses in this type of >installation is the correct approach. But there are times when an >intermittent short that opens a critical circuits breaker might result in >the pilots safe return with the ability to reset that breaker. I agree >that service work should not be performed in the cockpit while flying, >but I would rather have the ability to reset a breaker IF I NEED TO, and >it doesn't interferr with the control of the aircraft. Just my opinion. Let's try an ON-LINE FMEA (failure mode effects analysis). Over the next 24 hours, I'd like for people to post their response to the following questions: (1) Name one item of electrical equipment critical to safe completion of flight . . . or an item who's failure presents an immediate hazard to completion of flight. (2) List the ways in which this device or system might fail. (3) How will each of these failures become obvious to the pilot. Tomorrow, I'll carry the analysis of each response to the next step. This is just the kind of process we do in the "big" airplane business; it's a good exercise to know . . . Regards, Bob . . . AeroElectric Connection //// (o o) ==========oOOo=(_)=oOOo========== | | | Go ahead, make my day . . . | | Show me where I'm wrong. | ================================= Server 2.0b9); Fri, 10 Oct 1997 11:27:28 -0600 Date: Fri, 10 Oct 1997 11:13:40 -0500 From: Chris Anderson Subject: Re: COZY: The great breaker debate . . .Yeahbut..... <9710092240.AA03043@alliance.sybase.com> <19971009.204841.4863.0.GASobek@juno.com> At 10:38 AM 10/10/97, you wrote: > > (1) Name one item of electrical equipment critical to safe completion > of flight . . . or an item who's failure presents an immediate > hazard to completion of flight. The only eletric device that important in mine would be the electric pump to run the retracts. > > (2) List the ways in which this device or system might fail. Loss of fluid preasure. Power failure. Motor faulure. Pump failure. > > (3) How will each of these failures become obvious to the pilot. (respectivly) hyd. preasure idiot lamp in cockpit (green light for preasure over a set point red for under) meters when the gear don't come down, and the idiot lamp is red when the gear don't come down, and the idiot lamp is red From: lschuler@cellular.uscc.com Date: Fri, 10 Oct 97 12:05:53 -0600 Subject: COZY: Re: The great breaker debate . . .Yeahbut..... --simple boundary Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Bob Nuckolls wrote: >Let's try an ON-LINE FMEA (failure mode effects analysis). Over the >next 24 hours, I'd like for people to post their response to the following >questions: >(1) Name one item of electrical equipment critical to safe completion of flight . . . or an item who's failure presents an immediate hazard to completion of flight.< >(2) List the ways in which this device or system might fail.< >(3) How will each of these failures become obvious to the pilot.< >Tomorrow, I'll carry the analysis of each response to the next step. >This is just the kind of process we do in the "big" airplane business; >it's a good exercise to know . . . 1. Subaru SVX computer. 2. Short or open (just to keep it simple and keep away from the exotic single-sensor failure modes). Either of these may be either permanent or temporary depending on the actual source of the difficulty and any possible ability to clear it before "landing". Example maybe a short caused by a screw holding the circuit board in the chassis has come lose. 3. The engine quits in both cases. The affect is identical. Just thought I'd toss this out since you are keen on using stuff that wasn't designed in 1940 AND because I will be using a Subaru SVX with computer and (probably) full array of sensors. All of which were manufactured after 1992. Larry Schuler --simple boundary Content-Type: text/plain; charset=US-ASCII; name="RFC822.TXT" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="RFC822.TXT" Received: from gatekeep.uscc.com by cellular.uscc.com (ccMail Link to SMTP R8.00.01) ; Fri, 10 Oct 97 10:44:57 -0600 Return-Path: Received: from www.uscc.com (www.uscc.com [204.179.101.2]) by gatekeep.uscc.com with ESMTP id LAA20555 for ; Fri, 10 Oct 1997 11:41:39 -0400 (EDT) Received: from palrel1.hp.com (palrel1.hp.com [156.153.255.235]) by www.uscc.com with ESMTP id KAA16082 for ; Fri, 10 Oct 1997 10:42:26 -0500 (CDT) Received: from hpwarhw.an.hp.com (hpwarhw.an.hp.com [15.57.193.122]) by palrel1.hp.com (8.8.6/8.8.5tis) with SMTP id IAA14473 for ; Fri, 10 Oct 1997 08:44:31 -0700 (PDT) Received: by hpwarhw.an.hp.com (1.37.109.8/15.5+IOS 3.22) id AA19577; Fri, 10 Oct 1997 11:43:46 -0400 Received: from relay.hp.com by hpwarhw.an.hp.com with SMTP (1.37.109.8/15.5+IOS 3.22) id AA19572; Fri, 10 Oct 1997 11:43:44 -0400 Received: from dtc.net (dtc.net [206.242.217.15]) by relay.hp.com (8.8.6/8.8.5tis) with ESMTP id IAA15627 for ; Fri, 10 Oct 1997 08:41:30 -0700 (PDT) Received: from p3.ts1.dtc.net (p3.ts1.dtc.net [205.183.130.3]) by dtc.net (8.8.5/8.8.5) with SMTP id PAA09943; Fri, 10 Oct 1997 15:43:25 GMT Message-Id: <3.0.1.16.19971010103823.2807ce24@dtc.net> X-Sender: nuckolls@dtc.net X-Mailer: Windows Eudora Light Version 3.0.1 (16) Date: Fri, 10 Oct 1997 10:38:23 To: rv-list@matronics.com From: "Robert L. Nuckolls, III" Subject: COZY: Re: The great breaker debate . . .Yeahbut..... In-Reply-To: <19971010.081543.3350.6.wstucklen1@juno.com> References: <9710092240.AA03043@alliance.sybase.com> <19971009.204841.4863.0.GASobek@juno.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: owner-cozy_builders@hpwarhw.an.hp.com Precedence: bulk Reply-To: "Robert L. Nuckolls, III" --simple boundary-- by x9.boston.juno.com (queuemail) id V`D15527; Mon, 13 Oct 1997 21:01:04 EDT Date: Sun, 12 Oct 1997 10:53:43 -0400 Subject: COZY: Re: The great breaker debate . . .Yeahbut.....but... From: unick@juno.com (Nick Ugolini) When I wired my LongEZ, I followed Bob's advice (through personal discussions with him and his book). I used with FUSES. I loved the result. I have talked with aviation shops and found breakers to be highly unreliable in their protection ability. Conversely every one said a fuse pops exactly when it is supposed to. I have a bag full of "aviation brakers" I picked up for wiring my plane and they are still setting on the shelf. I elected to go with the B&C fuse block... a 10 and 20 for a total of 30 fuses and their ground strip (I think it has 40+, 1/4" spade push on connections. The fuse blocks are very small and are located in the nose of the plane well out of reach. I have ONE breaker for the alternater field which is "accessible to the pilot" as required by the FARS for a IFR plane. I have EVERY single circuit fused. Each selenoid, each radio, gear warn circuit, the little LEDs for the fuel level lighting, even the instrument pannel light circuit has its own fuse, and I still have spare fuse holders. If for some reason I lose a circuit I have got a REAL problem, and I only lost one circuit, not a bunch of things all hooked up to one breaker which is how you typically wire a plane. Think about it, when was the last time you blew a fuse in your car? From: Fritzx2@aol.com Date: Mon, 13 Oct 1997 22:45:25 -0400 (EDT) Subject: Re: COZY: Re: The great breaker debate . . .Yeahbut.....but... In a message from Nick Ugolin: << The fuse blocks are very small and are located in the nose of the plane well out of reach. >> How do you replace one in flight if it is "out of reach"? John Fritz fritzx2@aol.com Date: Tue, 14 Oct 1997 18:13:57 From: "Robert L. Nuckolls, III" Subject: COZY: Re: RV-List: Re: The great breaker debate >Date: Tue, 14 Oct 1997 18:12:24 >To: rv-list@matronics.com >From: "Robert L. Nuckolls, III" >Subject: Re: RV-List: Re: The great breaker debate >In-Reply-To: <199710140155.SAA02516@norway.it.earthlink.net> > >At 08:53 PM 10/13/97 +0000, you wrote: >>--> RV-List message posted by: "Tim Lewis" >> >> The "accessible breaker vs inaccessible fuse" debate is interesting >>to watch, and Bob Nuckoll's articles have had an impact on how I >>designed my electrical system (RV-6AQ, panel mostly done). I don't >>agree with everything Bob advocates, but he provides a lot of good >>food for thought. >> > > My reply to this is extensive . . rather than use up space here > I'll suggest those interested in reading it hop over to: > > > > Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= by x9.boston.juno.com (queuemail) id VQG18784; Tue, 14 Oct 1997 21:44:39 EDT Date: Tue, 14 Oct 1997 16:04:42 -0400 Subject: COZY: Re: The great breaker debate . . .Yeahbut.....but... From: unick@juno.com (Nick Ugolini) The fuses are mounted on a bracket in the nose next to the battery. Access is granted through the battery cover. The single breaker for my Alt. field is located next to my main non-vital bus switch. ' Total cost for 30 fuses and 1 breaker was $35 if I recall correctly. Date: Tue, 14 Oct 1997 19:42:42 -0400 From: Jim Hocut Subject: COZY: Re: The great breaker debate . . .Yeahbut.....but... It had slipped my mind, but there have been two occasions when I was glad I was flying a plane that had breakers instead of fuses. Once 'twas a Cessna-172RG, and the other time 'twer a Piper Arrow. The breaker for the gear's hydraulic pump tripped when the gear was in transit. Once reset it was fine. True I could have pumped the gear on the 172RG, and true the gear will free fall on the Arrow. And true there probably was some physical problem with the motor or pump that needed attention (these are rental planes after all), but it sure was nice to be able to reset the breaker and continue on. Jim Hocut jhocut@mindspring.com Date: Wed, 15 Oct 1997 00:43:59 +0000 From: Dean Arthur Subject: Re: Europa_Mail: Re: COZY: Re: The great breaker debate . . .Yeahbut.....but... cdenk@ix.netcom.com wrote: > > Nick Ugolin writes unreliable > > Murphey's Law will prevail, what can go wrong, will go wrong. One of the main failure modes > of fuses is vibration with the little wire breaking. I have replaced more than my share of > glass cylindrical fuses on autos, trucks, and farm equipment wher there was no electrical > fault. Just replaced the fuse, and worked for years. Also I usually have dropsy in flight > and in turbulence at night I would anyday go for the circuit breaker. I have replaced 1 in > 500 hours. > > Carl Denk: "cdenk@ix.netcom.com" > ______________________________________________________________________ > The Europa List is supported by Aviators Network UK - info@avnet.co.uk Capture a fuse block from newer American design cars using plastic fuse plug with "Z" shaped fuse link. NO CHANCE of those suffering vibration breakage. The amount of vibration required would most assuredly shake the plane to pieces first! From: cdenk@ix.netcom.com Date: Tue, 14 Oct 1997 21:13:21 -0500 (CDT) Subject: Re: COZY: Re: The great breaker debate . . .Yeahbut.....but... Nick Ugolin writes Murphey's Law will prevail, what can go wrong, will go wrong. One of the main failure modes of fuses is vibration with the little wire breaking. I have replaced more than my share of glass cylindrical fuses on autos, trucks, and farm equipment wher there was no electrical fault. Just replaced the fuse, and worked for years. Also I usually have dropsy in flight and in turbulence at night I would anyday go for the circuit breaker. I have replaced 1 in 500 hours. Carl Denk: "cdenk@ix.netcom.com" Date: Tue, 14 Oct 1997 21:26:16 -0500 (CDT) From: cdenk@ix.netcom.com Nick Ugolin writes Murphey's Law will prevail, what can go wrong, will go wrong. One of the main failure modes of fuses is vibration with the little wire breaking. I have replaced more than my share of glass cylindrical fuses on autos, trucks, and farm equipment wher there was no electrical fault. Just replaced the fuse, and worked for years. Also I usually have dropsy in flight and in turbulence at night I would anyday go for the circuit breaker. I have replaced 1 in 500 hours. Carl Denk: "cdenk@ix.netcom.com" Date: Wed, 15 Oct 1997 09:41:27 -0700 From: Paul Messinger Organization: MTF Industries Subject: Re: Europa_Mail: Re: COZY: Re: The great breaker debate . . .Yeahbut.....but... Dean Arthur wrote: > > cdenk@ix.netcom.com wrote: > > > > Nick Ugolin writes > unreliable > > > Murphey's Law will prevail, what can go wrong, will go wrong. One of the main failure modes > > of fuses is vibration with the little wire breaking. I have replaced more than my share of > > glass cylindrical fuses on autos, trucks, and farm equipment wher there was no electrical > > fault. Just replaced the fuse, and worked for years. Also I usually have dropsy in flight > > and in turbulence at night I would anyday go for the circuit breaker. I have replaced 1 in > > 500 hours. > > > > Carl Denk: "cdenk@ix.netcom.com" > > ______________________________________________________________________ > > The Europa List is supported by Aviators Network UK - info@avnet.co.uk > > Capture a fuse block from newer American design cars using plastic fuse > plug with "Z" shaped fuse link. NO CHANCE of those suffering vibration > breakage. The amount of vibration required would most assuredly shake > the plane to pieces first! I agree that it's not vibration here that is the primary cause. The typical failure mode in fuses is a result of the slight heating and cooling between power on/off cycles and the lead alloy just finally separates. Fuses work by the heat generated by the excess current melting the lead alloy. There is less heat but still some under normal conditions. This fuse failure mechanism is seldom addressed in fuse - circuit breaker comparisons. The "Z" fuses are better than the glass tube design in this respect. I personally would never use a fuse in an acft. Nor would I put a fuse or CB where I could not reset it in flight. If the related equipment was not important to some mode of flight then it does not belong on the acft in the first place! Resetting the CB has saved me and the acft from harm three times in my 40 years of flying experience. BTW FAR 23.1357 (d) requires cockpit resetable (replaceable) Fuses/CB for "critical to flight equipment". Paul Aeronautical and Electronic engineer EAA Technical Counselor Commercial, Inst., CFI From: Epplin John A Subject: COZY: Re: The great breaker debate Date: Wed, 15 Oct 1997 13:21:39 -0500 Paul writes: > I agree that it's not vibration here that is the primary cause. > > The typical failure mode in fuses is a result of the slight heating > and > cooling between power on/off cycles and the lead alloy just finally > separates. Fuses work by the heat generated by the excess current > melting the lead alloy. There is less heat but still some under normal > conditions. This fuse failure mechanism is seldom addressed in fuse - > circuit breaker comparisons. The "Z" fuses are better than the glass > tube design in this respect. > > [Epplin John A] Agreed. In the days of large rotary inverters, some fused as high as 300 amps, the maintenance procedures usually called for a periodic replacement of these large fuses. On the Grumman G1, these were in a junction box located in a closet. I had the cover off once when the inverter was started. The fuses have a transparent cover over the element which allowed the red glow to be visible. This explained why they were to be replaced periodically. I think that the rotary inverters would be about the worse case torture to fuses, however even incandescent lamps have a short term inrush current far higher than their steady state value. Now, does anybody know why we have fuses or breakers in the first place? The answer is to protect the wiring, not the device on the end of it. Circuit protection should be sized for the size wire, regardless of the device on the end of it. The connected device should have any protection that it needs on its own. Lamp bulbs are sort of self protecting, motors may have a overheat switch, most electronic equipment has some sort of current limiting devices inherent in their design...etc.. There are a few limited applications that should not be reset in flight, one that is common is combustion heaters. I hear the arguments of accessibility, but my personal feeling is these should be in flight resettle or replaceable, except in very few special applications. Also, except for very high current devices which are not likely to be found on the type of aircraft discussed here, I prefer a good quality circuit breaker that can be manually opened in flight. The above discussion is worth exactly what you are paying for it. John epplin Mk4 #467 Date: Wed, 15 Oct 1997 12:47:37 -0700 From: Paul Messinger Organization: MTF Industries Subject: COZY: Re: The great breaker debate Epplin John A wrote: > > Paul writes: > > > I agree that it's not vibration here that is the primary cause. > > > > The typical failure mode in fuses is a result of the slight heating > > and > > cooling between power on/off cycles and the lead alloy just finally > > separates. Fuses work by the heat generated by the excess current > > melting the lead alloy. There is less heat but still some under normal > > conditions. This fuse failure mechanism is seldom addressed in fuse - > > circuit breaker comparisons. The "Z" fuses are better than the glass > > tube design in this respect. > > > > > [Epplin John A] > Agreed. In the days of large rotary inverters, some fused as > high as 300 amps, the maintenance procedures usually called for a > periodic replacement of these large fuses. On the Grumman G1, these > were in a junction box located in a closet. I had the cover off once > when the inverter was started. The fuses have a transparent cover over > the element which allowed the red glow to be visible. This explained > why they were to be replaced periodically. I think that the rotary > inverters would be about the worse case torture to fuses, however even > incandescent lamps have a short term inrush current far higher than > their steady state value. > > Now, does anybody know why we have fuses or breakers in the > first place? The answer is to protect the wiring, not the device on the > end of it. Circuit protection should be sized for the size wire, > regardless of the device on the end of it. The connected device should > have any protection that it needs on its own. Lamp bulbs are sort of > self protecting, motors may have a overheat switch, most electronic > equipment has some sort of current limiting devices inherent in their > design...etc.. > > There are a few limited applications that should not be reset in > flight, one that is common is combustion heaters. I hear the arguments > of accessibility, but my personal feeling is these should be in flight > resettle or replaceable, except in very few special applications. Also, > except for very high current devices which are not likely to be found on > the type of aircraft discussed here, I prefer a good quality circuit > breaker that can be manually opened in flight. > > The above discussion is worth exactly what you are paying for > it. > > John epplin Mk4 #467 John I agree with you, in particular with the "real purpose" of the breaker and also the "manual open" type of breaker. It is the only kind that I use and recommend. In many cases use of this type of breaker can eliminate the usual switch and combine both into one device. Consider a circuit that is typically always on. Why have a switch when this manual open breaker can provide both functions? Just leave it on all the time and you still have the capability to open the circuit if needed. There are even breakers with a bat handle for frequent on/off action. I am well aware with Bob's positions' on various subjects and agree with some and disagree with others. I firmly believe there are many good solutions to an issue and think differing opinions should be accepted with out the usual heat and smoke sometimes found. I have yet to meet another A&P, FAA rep, or EAA Tech coun. that agrees with Bob on remotely located fuses. That doesn't make his opinion wrong, just different than my data base and personal position. When I was on active duty in the USAF, we saved an average of one mission a month by being able to reset the breaker and continue. A couple of times a year this ability saved the acft. As you can see, I am biased based on real experience (USAF and 3 personal cases in civil acf), and all the numbers games in the world will not change my mind. Sure breakers trip when they shouldn't, and they are "on paper" less reliable than fuses. But I never heard of one totally failing open when the downstream device was good. Paul Date: Wed, 15 Oct 1997 20:55:54 -0700 From: "LCDR James D. Newman" Organization: INFINITY Aerospace - http://www.flash.net/~infaero Subject: COZY: Re: The great breaker debate Hi Paul and All, >Paul wrote: >When I was on active duty in the USAF, we saved an average of one mission a month by being able to reset the breaker and continue. A couple of times a year this ability saved the aircraft.< Yes, in my 2000+ hours flying F-14's with 800+ circuit breakers, flying several of the other military hardware and familiar with the rest, NATOPS said we could not cycle the circuit breakers more than 3 times if one popped. NATOPS also said not to hold the circuit breaker in if it's trying to remain popped. I always got a laugh out of that one (someone obviously tried holding it in which I'm sure caused a lot of problems). Bob, any comments on this pushing it in 3 times policy [I think I know what you will say ;-)]? As Paul said, several a mission was saved because we could reach a circuit breaker and just push it in. With all the glitches that came up in these aircraft made by the cheapest bidder, we actually used circuit breakers as ON/OFF switches, and for many other trouble shooting situations so we didn't lose a mission. In 5000+ civilian flight hours, I've only had one incident where I'm very glad I could reach and pull the circuit breaker. The instrument panel light rheostat in a Turbo Cessna 210 I was flying one very dark night shorted over the water (which I found out later that this is somewhat common[!?!] in Cessna's with their panel light rheostats), melting the wires and catching fire under the instrument panel - the circuit breaker didn't pop. The globs of melting wires on fire dripped/dropped onto my legs and caught my Navy uniform pant legs on fire. Except for my legs on fire providing the only light in the cockpit, everything went very black. If we would of had ejection seats, my fellow Naval Aviator riding along with me would have punched out. For a few moments, I thought he was going to crawl into the back seat or even open the door and drop into the ocean. I got the fire out and my friend calmed down, and landed uneventful using a flashlight. A lot of the panel had to be rebuilt and rewired, and I had a sunburn and shorts that needed trimmed and cuffs. I'm sitting here laughing to myself about that night as I write, but it wasn't very funny at the time and was almost a really big problem. So, I will probably always fly my plane in my Nomex flight suit, and I will have a shroud under the instrument panel above my legs so melting things and things on fire can not drop on my legs or in my lap again. I also have a fire extinguishing system for behind the instrument panel and in the engine compartment. Bob has brought up many good issues though. I've never considered putting all the CB's out of reach in the air, or to use fuses. But, as Bob said, our Sport Aircraft hopefully are better thought out and wired accordingly than spam cans. There has been a lot of other good points brought up by the group, also. I've always liked lighted switch circuit breakers, too :-(. Alternator, landing gear, maybe a few others - I'll have to noodle on this one. Thanks Bob and All. Infinity's Forever, JD Date: Thu, 16 Oct 1997 12:03:44 From: "Robert L. Nuckolls, III" Subject: COZY: fuses At 08:56 AM 10/16/97 -0700, you wrote: >As a 65 year old EE, I would like to make one small comment about the >discussion that has taken place over the last few days (I previously put my >two cents in re: fuses vs breakers--I am on the side of breakers--so I won't >go into that again). I do want to say however that the purpose of fuses or >breakers can be and often is far more than just to protect the wiring. This has indeed been an Operational consideration in the design of some aircraft systems and I'm sure the military and transport category aircraft have many examples in their POH. Thing is, most of these aircraft are flown with two or more crew; or if single pilot, one that does this stuff for a living . . . highly trained and paid to accept the risks the job brings with it. > You >can make the argument that the unit that blew the protective device has >already failed so it is not necessary to protect it further but in many >situations the rapid removal of power to the failed unit will prevent >further damage to that unit (cascading failures). Which puts the pilot's head down in the cockpit. The argument isn't just breakers/fuses . . . it's system architecture and operating philosophy. At first sign of trouble, I have but two switches MAX that need to be operated. There are operational Plan B's in place before the flight launches. I like to go flying fully prepared to complete the flight with the whole electrical system SHUT DOWN. I make many flights with no electrical system at all. Ya gotta spend some time in J-3's and C-120's to appreciate what CAN be done with a very rudimentary compliment of equipment. I made a cross country round trip a few years ago in a rental airplane where the alternator died minutes after home base departure. The trip wasn't difficult not so much for the equipment I had but for the confidence in the airplane's abilty to perform a desired task WITHOUT all the electrons. >And certainly one major >reason for PDs is to prevent fire, not just from the wiring to the unit or >in the unit but from other components as well. These are certainly true words but do they apply in any way to the airplanes we should be buidling? Many seasoned and experienced people bring a wealth of knowlege to this discussion. Much of it comes from an air transport/military background working with designs and operational philosophies that were developed 30 years ago. I don't doubt the validity and usefulness of their training in the machines they were FORCED to live with. We're building the best airplane flying today. We're not FORCED to live with anything . . . Bob . . . AeroElectric Connection //// (o o) ===========o00o=(_)=o00o========= | | | Go ahead, make my day . . . . | | Show me where I'm wrong. | ================================= by post.larc.nasa.gov (8.8.6.1/pohub4.1) with SMTP id KAA14632 for ; Thu, 16 Oct 1997 10:31:07 -0400 (EDT) Date: Thu, 16 Oct 1997 10:26:02 -0400 From: Paul Krasa Subject: Re: COZY: Re: The great breaker debate . . .Yeahbut..... When the time comes to wire your airplane and you estimate the number of breakers you will need to cover all the systems and then compare it to the panel space available. You will probably come o the same conclusion I did. Only put breakers and switches on the panel that are absolutely nessecary. All the rest off the circuits get a fuse. I used a ten fuse block using the new type blade fuses that I got at Skycraft in Orlando, FL. When you are at Sun n Fun take an afternoon and go to Skycraft. Skycraft has surplus aircraft wire, bus bars, switches, and just about any other electircal thing you can think of. Paul Krasa Long EZ 214LP p.s. By the way the fuse block was less than $10 a piece. Date: Thu, 16 Oct 1997 08:56:54 -0700 From: Michael Antares Subject: COZY: COZY; fuses As a 65 year old EE, I would like to make one small comment about the discussion that has taken place over the last few days (I previously put my two cents in re: fuses vs breakers--I am on the side of breakers--so I won't go into that again). I do want to say however that the purpose of fuses or breakers can be and often is far more than just to protect the wiring. You can make the argument that the unit that blew the protective device has already failed so it is not necessary to protect it further but in many situations the rapid removal of power to the failed unit will prevent further damage to that unit (cascading failures). And certainly one major reason for PDs is to prevent fire, not just from the wiring to the unit or in the unit but from other components as well. My further two cents... By the way, I just had the pleasure, after waiting a year, to move into a hanger. The Cozy building cycle has been on hold for a few months as I made the transition to a new living location and in the process lost the ability to build in a garage. But now I have a brand new hanger (Petaluma Muni) and will happily continue building once again. Yeah! 11597 Summerhome Park Road Forestville, CA 95436 707.887.7260 Cozy#413 Finished through chap 14 except chap 13. Chaps 16 & 24 mostly finished. Now on chap 20. One wing/winglet finished, working on second--almost finished. From: Epplin John A Subject: COZY: Electrical sysstem Date: Thu, 16 Oct 1997 11:12:56 -0500 Getting around to trying to collect my thoughts on electrical requirements. I have made a list of devices that normally would need breakers/fuses and panel switches. * Boost Pump * Nav Lights * Strobe Lights * Landing Lights * Instr. Lights * Cockpit Flood * Pitot Heat * Auto Pilot Navcom 1 Navcom 2 Gps Xponder Intercom Alt. Field Turn & bank Eng. Inst. Landing Gear Speed Brake Trim Items marked * require a switch as well as circuit protection. Have I missed anything? Does anyone have any feel for how much and what size wire to order? I would think 2 sizes would cover most uses, 16 ga and maybe 22 ga for the light load things. Will need small amount of heavier for buss feeder and main ground etc. I plan on a copper strip located near the instrument panel for a common ground forward and a substantial stud through the firewall near the battery for the engine and any rear mounted equipment. This is my thoughts at the moment, subject to change at any time. Just looking for input so I can do it right the first time. John Epplin MK4 #467 Date: Thu, 16 Oct 1997 18:10:29 From: "Robert L. Nuckolls, III" Subject: COZY: It's not JUST breakers/fuses . . . >I have yet to meet another A&P, FAA rep, or EAA T