Date: Wed, 7 Jan 1998 20:53:20 -0600 (CST) From: cdenk@ix.netcom.com Subject: COZY: Propellers Within the month, I should be flight testing several Sensenich Wood Propellers for the company. With a little luck, I hope they will be able to come up with a good performer. The other advantages are: 1: Made to same standards and quality control as their certified propellers. 2: Design is to FAR standards. 3: Available with urethane leading edges. 4: 2 or 3 week lead time if needed. 5: Cost for 2 blade around $700 - $800. If you are planning to buy a propeller in the future, suggest you wait to see what happens. I'll keep posted. p.s. they are a repair station, and repair/refinish other props. Subject: COZY: Prop Experiments - Tape on Prop From: mbeduhn@juno.com (Mark W Beduhn) Date: Sun, 25 Jan 1998 14:50:22 EST I did an experiment today with very interesting results: I have a Cozy Mark IV with a 3-blade 64 X 76 performance prop. (my wife loves how it lookes so much that she wanted to hang it on the wall when it arrived). It really is a work of art, so I just couldn't get myself to dig pits in its surface to test out the boundary layer effects that I have been reading about lately. Anyway, to simulate a dimpled surface, I took some extra copper foil tape that I used for my radio antenna, and textured the surface by laying it on some 80 grit sandpaper and rubbing the backside with an epoxy mixing stick. If you have seen this foil, it is very thin, and the texture I made was very subtle. Texture and all it is only a couple of mills thick. I stuck a strip to each blade at the highest point in the blade, and went flying. The results were dramatic to say the least. I ran a series of flights at full throttle, and then again at 2500 rpm (my usual cruising RPM). All flights were at a density altitude of 5000', and the temp was 42 degrees F, and the flights were within 1 hour of each other. Of course, the static RPM readings were on the ground (temp 47, and density altitude of -630'). Here are some representative numbers: With Tape Static RPM 2360 RPM 2700* 2500 Manifold 23.2 20.5 TAS(KTS) 169 154 No Tape (waxed blades) Static RPM 2390 RPM 2660** 2490 Manifold 24.2 22.4 TAS(KTS) 183 167 * Note: I was not able to run full throttle because of overspeeding the engine. ** Full Throttle When I landed, one of the pieces of tape had ripped off, but the other two were intact. As you can see, the performance was worse with the tape. I can't explain it, but there are the numbers. Keep in mind that this was a quick and dirty experiment, so don't draw too many conclusions. However, it does seem to indicate that small surface changes to the surface of a prop can have dramatic effects on its performance. Maybe dimples would work differently (better), but I'm not going to try it to find out. I'd be curious to see the results that others see with various prop modifications. Mark Beduhn Cozy 494CZ - 69 hours and having a blast (keep building - it's worth it!) Date: Sun, 25 Jan 1998 20:18:18 -0500 (EST) From: Nigel Field Subject: Re: COZY: Prop Experiments - Tape on Prop At 02:50 PM 1/25/98 EST, Mark Beduhn wrote: >I did an experiment today with very interesting results: >......snip....... Here are some representative numbers: > > With Tape >Static RPM 2360 >RPM 2700* 2500 >Manifold 23.2 20.5 >TAS(KTS) 169 154 > > No Tape (waxed blades) >Static RPM 2390 >RPM 2660** 2490 >Manifold 24.2 22.4 >TAS(KTS) 183 167 > >* Note: I was not able to run full throttle because of >overspeeding the engine. >** Full Throttle > >When I landed, one of the pieces of tape had ripped off, but the other >two were intact. As you can see, the performance was worse with the >tape. Excellent work Mark. I think its great when someone performs a controlled test then posts their data and conclusions. Been following these prop drag discussions and claims with considerable interest. Plan some trials myself, thought about attaching some narrow strips of sandpaper to the top blade surface with contact cement at about the 33% chord point and see what happens. But I have found in the past that a freshly cleaned and waxed prop performs noticeably better than when its all bugged up. That could be due to the roughness on the leading 1/3 where it is detrimental to laminar flow. If anyone else tries this experiment please post your data, its facinating. Mark, ya done good, take the rest of the day off. Nigel Field Date: Mon, 26 Jan 98 8:31:59 EST From: "Nick J Ugolini" Subject: COZY: Prop Tape At 02:50 PM 1/25/98 EST, Mark Beduhn wrote: >I did an experiment today with very interesting results: >......snip....... Here are some representative numbers: > > With Tape >Static RPM 2360 >RPM 2700* 2500 >Manifold 23.2 20.5 >TAS(KTS) 169 154 > > No Tape (waxed blades) >Static RPM 2390 >RPM 2660** 2490 >Manifold 24.2 22.4 >TAS(KTS) 183 167 > I wonder if the tape edges could have affected your numbers (as opposed to cutting into the prop). I tried the 3M polyurathaine leading edge tape (saw it at Oshkosh) on my LongEZ GU canard... Just the slight transition of the tape edge was enough to distrupt the air flow over the canard. I had to use lots more trim.. Ended up taking the tape off. Date: Mon, 26 Jan 1998 09:34:13 -0800 From: C Van Hoof Subject: Re: COZY: Prop Experiments - Tape on Prop Hi Dimple Testers' > Been following these prop drag discussions and claims with considerable > interest. Plan some trials myself, thought about attaching some narrow > strips of sandpaper to the top blade surface with contact cement at You can get this cheap at the sportstore, the kids use this for their skateboards, its about 36 grit coarse and has adhesive installed. The stuff i saw was clear. Sold in sandpaper sheet width and about twice as long. FWIW chris #219 From: "astrong" Subject: COZY: Tape on prop. Date: Mon, 26 Jan 1998 20:39:20 -0800 I have been following the dimpled prop. discussion and feel I have to say something. A friend of mine had a Mooney M-20 . He had to taxi across a gravel road and did not want to damage his new prop. so he put a layer of duct tape on the leading edge of the prop. A few days later he flew the plane, could not take off and hit an embankment at the end of the runway he forgot to remove the tape. The plane was totaled, there was no fire and John survived. We later took a similar plane on a dry lake with plenty of room and simulated what he did, we could get the RPM but could not get up to take off speed. The tape apparently created enough turbulence that destroyed the props efficiency and we might as well be flying with a 2X4. We estimated we rolled 4000` You guys be careful. There I feel better!. Alex A.R.Strong Homepage "http://www.canard.com/trim" "When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will long to return" `Leonardo DaVinci` From: cdenk@ix.netcom.com Date: Tue, 27 Jan 1998 20:19:18 -0600 (CST) Subject: COZY: Prop design software?? A month ago someone had propeller design software. Was the offer for a copy of the software, to run a design or what? Is the software public domain? What is the name author of the software? What are the design assumptions (Airfoil, etc.) Do the work well on EZ's with 320? From: Marc J. Zeitlin Subject: COZY: Prop design software?? (fwd) Date: Tue, 27 Jan 98 23:40:53 EST Carl Denk asks; >A month ago someone had propeller design software. Was the offer for >a copy of the software, to run a design or what? The propeller design software is available from: Bates Engineering 2742 Swansboro Road Placerville, CA 95667 916-622-1886 http://www.innercite.com/~bateseng >........ Is the software public domain? Nope. It was about $100 (bought it with my visa card from the web page. >....... What are the >design assumptions (Airfoil, etc.) Do the work well on EZ's with 320? I haven't used it much yet - Nigel Field is probably the expert on this, but AFAIK it will give you the coordinates for a good propeller for whatever conditions you'd like to optimize for - HP, climb, cruise, drag, etc. There are a zillion inputs, and it's pretty crude (DOS interface and all) but I think the basis for the analysis is pretty sound (from what I've read in the manual and others have told me). Nigel has used this to design his propeller on his V.E., and many in the PROP-FAB mailing list are using it to design the props for their L.E.'s and COZY's. -- Marc J. Zeitlin Email: marcz@an.hp.com From: cdenk@ix.netcom.com Date: Wed, 28 Jan 1998 20:19:48 -0600 (CST) Subject: COZY: Sensenich Prop testing Flight tested 2 Sensenich wood 2 blade props this week, in addition to my Performance Prop as a base line. The results are encouraging. The 2nd prop tested had better performance than the first. I expect to flight test 1 or 2 more props within the next 2 or 3 week. One will probably be the same design as the last with approximately 2 inches more pitch. If there is another prop it will be a different design. Making things legal for the testing turned out to quite a chore, the F.A.A. (Although very cordial), required a new airworthness certificate as "Research and Development" for the testing, and then in several weeks I will receive another certificate back to "Amateur Built". This required a check with Avemco Insurance to ensure coverage with the new certificate. Everyone cooperated time wise, the Sensenich Engineer arrived Monday Noon, did a benchmark flight with him and the Performance Prop Monday P.M., F.A.A. arrived early Tuesday early A.M. (no passengers, usual flight test area), replace engineer's weight with 150 lbs. sand bags and adjusted fuel load to duplicate loading, flight tested fist prop in A.M., 2nd prop in P.M. Weather cooperating excellent, first sun we had seen in a month and moderate (for this time of year) temperatures. Engineer left Noon Wednsday, an I did 1 more flight of second prop after some minor touchup of prop. Wife almost had to pick me up a another airport, when fog rolled in off lake erie at end of flight. Flights Consisted of climbing to 8,000 or 10,000 feet at 100 Knots, Level flight with data collected starting at 2000rpm, and 200 rpm increments to the 2700 rpm redline, or if near full trottle would exceed redline by 50 rpm. Data included Indicated airspeed, Outside temperature, rpm, manifold pressure, time at every 1000 feet. altimeter was set to 29.92. Here is a small part of the data, When the testing is complete I will try to post a complete set for the best prop. Note that these flights do not necessarily represent my normal operations, but are an attempt to be impartial with repeatable reliable useful data. Note that the aircraft was purposefuly loaded to a heavy weight to accent takeoff distances. Takeoff distance was very difficult to determine on so few flights. Aircraft: Cosy Classic, N5EN, Empty Weight 1168 lbs. Takeoff Weight 1834 lbs. Engine: Lycoming IO-320-B1A, 160 HP. Weather: Temperature: @ takeoff: 35 - 40 F., @ 8,000" 20F +/- Wind approx. 7 knots maximum. Description Performance Prop Sensenich Prop Static RPM 2215 2210 Takeoff Distance 2200 1850 Climb to 8000' @ 100Knot IAS 9:19 8:38 @2000' TAS knots 177 @ 2700RPM 173 @ 2700 RPM @8000' TAS Knots 167 @ 2610RPM 180 @ 2700 RPM @10,000' TAS ----- 180 @ 2750 RPM I would prefer a prop with a little more effective pitch than the Performance prop, hopefully the next Sensenich will provide that. After I removed the Performance Prop, a small crack in the hub area was found to be growing, and an acetic acid oder was noted. Either defect is grounds to retire (after 250 hours in 2.6 years), which will happen. The Sensenich props are designed and made to F.A.A. standards, for certified aircraft. It is possible also to certify props for experimental aircraft/ engine combinations, but I don't know if a the completion of this testing whether that will happen. Delivery usually is around 1 month at competive costs. From: cdenk@ix.netcom.com Date: Sun, 1 Mar 1998 21:11:45 -0600 (CST) Subject: COZY: Performance formulas wanted. I am looking for formulas (not tables) for conversion of data related to my propeller testing. Conversions to standard conditions Conversions to various altitudes, temperatures. Rate of climb, and speed rules of thumb. What type (power, exponent, etc) rate of climb vs. altitude. Lycoming 160 HP. power curves reduced to a FORMULA. Subject: COZY: 8" Prop extension From: mbeduhn@juno.com (Mark W Beduhn) Date: Thu, 05 Mar 1998 17:53:13 EST On Wed, 4 Mar 1998 11:55:18 -0600 "Nat Puffer" writes: >Dear Mark, >Didn't you say you were going to try an 8 inch prop extension and tell >me how it worked out?Do I remember correctly? How is it doing? Regards, >Nat > Nat, I have the same 3 blade performance prop that you list in the owners manual with an 8" prop extension. Maybe that is part of the reason my plane is so quiet. I took sound measurements again yesterday and got 92 db (full throttle at 5000'). Based on what I have been reading lately, my plane is several db quieter than normal. When I take other pilots for rides, the first thing they notice is the fantastic visibility, the second thing they notice is how smooth and quiet it is. Of course the Cessna pilots are totally green when they look at the airspeed indicator! Thanks for the great design! I hope to see you and Shirley at Oshkosh and then Copper State. I wanted to go to Lakeland, but it looks like I won't be able to get off from work. Mark Beduhn Cozy IV N494CZ _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] Date: Tue, 17 Mar 1998 16:09:59 -0800 (PST) From: Jannie Versfeld Subject: COZY: Constant Speed Propeller Hi all, I saw a couple of pictures of Tim Merril's Cozy. It had a IO-320 fitted with a two bladed constant speed prop. Has anyone got any more info on building or modifying existing hubs for pusher use? Who can be contacted for a similar propeller as Tim's. Will a three blader reduce prop resonance? Thanking you in advance, Jannie Versfeld From: cdenk@ix.netcom.com Date: Tue, 17 Mar 1998 20:21:39 -0600 (CST) Subject: Re: COZY: Constant Speed Propeller Tim Merrill has an M & T constant speed prop made in Germany. They are very nice, about $8000, and heavy adding possibly 15 or more pounds at what is not a good location. From: N11TE Date: Tue, 17 Mar 1998 23:01:09 EST Subject: Re: COZY: Constant Speed Propeller Jannie: Tim Merrill's Oskosh Grand Champion Cozy MKIV has an IO-320 B1A engine (160 hp) with a two-blade constant speed Hoffmann Propeller. The Hoffmann Propellers are made in Germany. I have just been appointed as a distributor for Hoffmann Propellers for pusher applications here in the US. The Cozy MKIV is designed for the heavier O-360 engine so an IO-320 with a constant speed prop may end up being about the same weight and balance. I had a long conversation with Tim Merrill before taking on the line and he reported he was very pleased with his installation. I know he will be happy to discuss it directly with anyone who might be interested. Also, the smaller IO-320 (and even the 180 hp O-360) can use a lighter weight Hoffmann model. The HO-72 weighs only 34.2 lbs, and can very favorably compare with the total weight of a 3-blade wood prop and 8-in. extension. I just received the first propeller that was ordered for another builder (this one a three blade model for an IO-360) and was able to have Hoffmann build in the 8-in. extension into their prop. It was a very well made unit and included an aluminum spinner that was a work of art. They also offer an automatic versions of their props which could be used by those with solid cranks. For anyone interested, I will be happy to provide a written proposal for any installation. Either e-mail or telephone me so I can get the detail needed. The only other light weight propeller being made is the MT Prop. Also made in Germany. The man that started MT came from Hoffmann. The longest extension MT offers is 6 inches. I priced the MT for my plane and can assure you of better prices from Hoffmann. I am not doing this as a living... more as a service to other builders. As always, you should be very careful about adding weight to the aft end. In my case I knew I wanted a heavier engine and a constant speed prop so I have moved all items as far forward as I could while building. For example, my calculations show that moving the battery from the main spar to the nose will balance 85 pounds of additional engine/propeller weight by itself. These are decisions that you, alone must make for your own plane. Good luck! Tom Ellis Cozy MKIV plans #25 AeroCanard 540 N11TE@aol.com (812) 867-2275 From: N11TE Date: Tue, 17 Mar 1998 23:09:48 EST Subject: Re: COZY: Constant Speed Propeller Carl Denk: The propeller on Tim Merrill's plane is a Hoffmann Propeller, not an MT. The price for that model is much less than the $8,000.00 you mentioned in your post, and weight and balances very favorably with the lighter weight IO-320 engine. See my reply to Jannie Versfeld for more complete information. Tom Ellis Cozy MKIV plans #25 AeroCanard 540 From: cdenk@ix.netcom.com Date: Thu, 26 Mar 1998 21:15:42 -0600 (CST) Subject: COZY: Propeller failure !! ------Begin forward message------------------------- Return-Path: Received: from m2.boston.juno.com (m2.boston.juno.com [205.231.101.199]) by ixmail4.ix.netcom.com (8.8.7-s-4/8.8.7/(NETCOM v1.01)) with ESMTP id = DAA21131;=20 for ; Tue, 24 Mar 1998 03:15:39 -0800 (PST) Received: (from jschuber@juno.com) by m2.boston.juno.com (queuemail) id GGZ01551; Tue, 24 Mar 1998 06:15:15= EST To: cdenk@ix.netcom.com Date: Mon, 23 Mar 1998 22:52:15 -0500 Subject: Re: Hood (not criminal) Message-ID: <19980324.061125.9822.1.jschuber@juno.com> References: <1998323213252241@> X-Mailer: Juno 1.49 X-Juno-Line-Breaks: 0-1,13-14,22-23,34-35,44-45,61-62,66-67 From: jschuber@juno.com (Janet L Schubert) 2 Blade Performance Prop Failure=20 Sam McReynolds - (AR) On take off roll from our home airstrip with about 55-60 MPH and 2425 RPM, I suddenly felt an unusual vibration and a decrease in forward momentum. Not a startling vibration, but enough to make me aware something unusual had happened. I instantaneously chopped throttle to abort the take off. My first thought was a flat tire but that was ruled out because the Long-EZ tracked straight during braking.=20 As speed approached zero, I added throttle to clear the runway and experienced a FEROCIOUS vibration!!! I immediately pulled the mixture knowing that a major problem existed aft of the firewall. Outside the aircraft, a quick look revealed about 2-1/2" missing off the one propeller blade end and a 15" split up the center toward the hub. The other end was perfect. This flight began 55 minutes earlier with touch and go landings at two other airports immediately prior to the final landing and aborted take off. Our airstrip is highly maintained with Bermuda Sod in sandy loam without rocks or gravel. No birds, animals or other hazards were observed during take off. A close inspection of the airstrip in the area where the vibration was first felt revealed no evidence of hitting anything or propeller fragments. There were no screws, bolts, etc. missing from the aircraft. The propeller was purchased from Performance Propellers in March, 1995 and had 150 hours on it with out incident. It had never been nicked, scratched, scrapped, etc. and was always clocked at the 1/7 o=92clock position. No erosion from rain or other elements is visible nor is evidence of over heating. The only flaw (which I considered negligible, at least prior to this experience) was a couple of small, pin head size dimples 1/16" across and .003" deep that appeared about 30 to 40 hours ago located 2 to 3 inches inboard from the tip in the center of the flat side. The paint was not scratched or scraped but had a hairline crack for 170 degrees around the dimple=92s circumference. I was unable to theorize the cause of this.=20 What happened to the propeller? I do not have a definitive answer. My experience with matters such as this has been that extended evaluations by experts often fail to provide THE answer . . . . lots of different assumptions, theories, speculations and probabilities with outcomes often shaded by who pays the bill or what ax they might want to grind.=20 Therefore , I have presented the facts here as I know them so each individual can draw his/her own conclusion. After all, each pilot/owner is the one ultimately responsible for the safe operation of the=20 aircraft. In reaching my personal conclusions, I recruited my neighbor on the airstrip to help me with the analysis. He has also been flying since the fifties with lots of wooden propeller experience. Our approach was simple, the propeller hit something or it did not. Since we could find no evidence of it hitting anything, we had to conclude that there was a possibility of propeller tip failure. The initial non-violent vibration and subsequent violent one when power was applied seems to support this theory. When you look at how thin the wood is in this area, even the slightest flaw in the construction or materials makes this plausible. I must now admit that I silently questioned the fragility of this propeller when I first saw it. We further concluded that if it did hit something, it was likely a small object. Otherwise we would have found some evidence on the ground. If that was the case, a less fragile propeller would not have been as likely to self-destruct. In view of these conclusions and firmly believing in the "old-bold pilot rule" my Long-EZ now has a more substantial propeller. I discussed this with Clark at Performance Propellers who reports no structural problems with these problems and says this type is still in production. Without hesitation, he concluded the prop was hit by some object. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] ------End forward message--------------------------- Date: Sun, 29 Mar 1998 20:37:50 -0500 From: Tom Teek Subject: Re: COZY: Propeller failure !! HI I read with interest this prop failure and have a question. Were the two landings at another airport on grass or tarmac. Here in Merrrit Island a Long-eze pilot took off over water. It was duck season and some one(never found) took a shot at the plane at when he was approx 75' above the runway. At 900' the prop shattered, and due to his superior pilot skills he was able to do a 180 and return to the runway,albeit the landing was at approx 160Kts!!He safely overran the runway on to grass and suffered minor damage to the plane. Shot was found imbedded in the prop,and dings were found on the cowling as well as the lower winglet. My point is that anything imbedded in a multilaminated prop (his was a ted hendrickson) can cause separation. Could he possibly have picked something up at the other airports? As a user of a Perf Prop (with no complaints I sure would like to know all that is discovered here as I'm sure all other owners would. Is this a Performance problem or a laminate problem? Tom LE N58AT Date: Wed, 1 Apr 1998 09:02:43 -0800 Subject: Re: COZY: Propeller failure !! From: alwick@juno.com (ok How) On Thu, 26 Mar 1998 21:15:42 -0600 (CST) cdenk@ix.netcom.com writes: snip > >The propeller was purchased from Performance Propellers in March, 1995 >and had 150 hours on it with out incident. It had never been nicked, >scratched, scrapped, etc. and was always clocked at the 1/7 o=92clock >position. No erosion from rain or other elements is visible nor is >evidence of over heating. The only flaw (which I considered negligible, >at least prior to this experience) was a couple of small, pin head size >dimples 1/16" across and .003" deep that appeared about 30 to 40 hours >What happened to the propeller? I do not have a definitive answer. Thanks for sharing the failure info. By cooincidence Klaus Saviour gave a lecture at our EAA meeting just the day before this post. Basically he described the Perf Prop design as "pushing the envelope". You are putting out x hp with a much thinner cross section of wood than normal. So load per sq in is increased. Sounds like reasonable assumption to me. (FWIW, Klaus is at beginning stages of designing composite props) On the other hand, wood props fail all the time. I had two fail on my ultralight pusher within 2 hrs total time. My tires are too close to the prop arc zone and pebble kicked up by tire did it's thing. -al wick 71% comp. Cozy MkIV sn 389 with stock Subaru 2.5 engine. Computerized cockpit. Working towards engine ignite. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] From: cdenk@ix.netcom.com Date: Wed, 1 Apr 1998 16:41:45 -0600 (CST) Subject: Re: COZY: Propeller failure !! On 04/01/98 09:02:43 you wrote: > >On Thu, 26 Mar 1998 21:15:42 -0600 (CST) cdenk@ix.netcom.com writes: >snip >> >>The propeller was purchased from Performance Propellers in March, 1995 >>and had 150 hours on it with out incident. It had never been nicked, >>scratched, scrapped, etc. and was always clocked at the 1/7 o=92clock >>position. No erosion from rain or other elements is visible nor is >>evidence of over heating. The only flaw (which I considered negligible, >>at least prior to this experience) was a couple of small, pin head size >>dimples 1/16" across and .003" deep that appeared about 30 to 40 hours > >>What happened to the propeller? I do not have a definitive answer. > >Thanks for sharing the failure info. By cooincidence Klaus Saviour gave a >lecture at our EAA meeting just the day before this post. Basically he >described the Perf Prop design as "pushing the envelope". You are putting >out x hp with a much thinner cross section of wood than normal. So load >per sq in is increased. Sounds like reasonable assumption to me. (FWIW, >Klaus is at beginning stages of designing composite props) >On the other hand, wood props fail all the time. I had two fail on my >ultralight pusher within 2 hrs total time. My tires are too close to the >prop arc zone and pebble kicked up by tire did it's thing. > >-al wick >71% comp. Cozy MkIV sn 389 with stock Subaru 2.5 engine. Computerized >cockpit. >Working towards engine ignite. > >_____________________________________________________________________ >You don't need to buy Internet access to use free Internet e-mail. >Get completely free e-mail from Juno at http://www.juno.com >Or call Juno at (800) 654-JUNO [654-5866] > > > Sorry for including the whole message, but I felt necessary for clarity. The prop isn't one of mine. At this time I have last weekend given one unairworthy Performance Prop to the receptionist at the airport for her mantle, a second unairworthy performance prop that is promised to another friend's mantle. There is also 3 Sensenich props in the basement, one will be returned shortly, and the other two, I'm in the process of buying. The message was information from Terry Schubert, which I felt important enough to get out to everyone ahead of the Central States newsletter. The newsletter that I received today has a picture and lengthy article of the failed prop. I have received one E-mail that indicated there was a V-EZ that had the prop strike the turf with a similar failure. Terry Schubert suggesed to the owner of the prop, send it to the Forest Products Laboratory in Madison, Wisconsin. I think that would be an excellent idea, and help everyone. From: Lee Devlin Subject: Re: COZY: dimple tape Date: Mon, 4 May 98 9:01:10 MDT Vance's report is about the 4th or 5th I've read about trying to duplicate the results of the Sport Aviation article published a few months ago. The sensational dimple tape article made it sound like it was an easy way to pick up 5 to 10kts and cut down on the prop noise which is akin to magic. So far, I've not heard of any success stories using this dimpling approach. I think the guy who wrote the article wants to sell the tape for something like $6 or $10/ft with a 20 ft minimum. I guess the old saying 'If something sounds too good to be true, it probably is' applies here. Lee Devlin LongEZ N36MX From: Jim Hocut Subject: RE: COZY: dimple tape Date: Mon, 4 May 1998 10:00:55 -0400 Lee Devlin wrote: > Vance's report is about the 4th or 5th I've read about trying to > duplicate the results of the Sport Aviation article published a few > months ago. .............I think the guy who wrote the article > wants to sell the tape for something like $6 or $10/ft with a 20 ft > minimum. > > I guess the old saying 'If something sounds too good to be true, it > probably is' applies here. Seems that Sport Aviation has been carrying "articles" on a regular basis lately where the author has something to sell. One has to wonder if that's really in the best interest of sport aviation, (and of course the next obvious question is how much the EAA is making off the deal). Date: Sun, 03 May 1998 09:24:58 -0700 From: vance atkinson Subject: COZY: dimple tape Two weeks before Sun-n-Fun I put some dimple tape on my great american prop. here is what happened. I called the manufacture who was going to make it and sell it and found out the tape was 17 thousandths thick. I called 3-M and ordered a roll . That took a month to get it. I then proceeded to punch in all the little holes using a gasket punch. That took another month. JUST KIDDING ! The application process of the tape takes a couple of hours and the bottom line is the day we left for Florida (via several other states) was the first test flight. I took it up for 10 minutes landed and noted nothing horrendously wrong so we loaded up and left for the East coast. We flew about 23 hours on that trip and sadly, no change was noted, good or bad. I could not detect any sound difference. At around 16 hours I noticed one tape starting to peel at the end of the prop tip. On the previous leg we had flown though some moisture (about 10 min. worth of in and out of Florida's low clouds with no rain.) I then went ahead and peeled all the rest of the tape off and as we flew along on the next leg noted once again, no change. This is the only place I have put the tape on as you are required to sand the surface free of any defects before application. I agree with Klaus in that if you have a properly designed airfoil you most likely will not benefit from this tape. I am still planning on applying the tape on the landing gear legs top and bottom, as they are probably the most inefficient airfoil on the plane. I would not recommend using this tape on the canard but instead, vortex generators to help your canard to "smooth out in the rain". This tape is made for helicopter blades and costs about 90 bucks a 100' roll when ordered singly from 3M. Vance Atkinson Cozy N43CZ 1200hrs TT From: cdenk@ix.netcom.com Date: Thu, 4 Jun 1998 06:33:35 -0500 (CDT) Subject: COZY: ScotchCal wanted A short time ago someone had access to ScotchCal protective film. As part of my propeller testing, I now have considerable flight data accumulated. If I had some Scotchcal (2 pieces 1" x 24"), I will flight test and determine if there is a penalty, and how it works as rain protection. Can anyone help. p.s. The ScotchCal works great on the hood of my Ford Broncos, its available as diecut kits for many vehicles and easy to apply, just follow directions exactly. Date: Fri, 5 Jun 98 8:17:28 EDT From: "Nick J Ugolini" Subject: COZY: ScotchCal wanted >A short time ago someone had access to ScotchCal protective film. As part of my propeller testing, I now have considerable flight data accumulated. If I had some Scotchcal (2 pieces 1" x 24"),< Umm, sound similar to 3M Leading Edge Tape. After constructing my propeller (3 bladed), I used the 3M Tape for LE rain protection. Cut the tape 18" X 1" X 1/2". Stretch it slightly as you apply it starting at the blade tip and working toward the hub. By stretching the tape it will neatly fold itself around the prop with no wrinkles. I have 45 hrs on the LE tape (75hr TT on prop) and it works very well. I routinely run 2550 rpm in the rain with no effect on the prop. The tape does not seem to affect the performance of the prop in any way. From: cdenk@ix.netcom.com Date: Fri, 10 Jul 1998 22:13:06 -0500 (CDT) Subject: COZY: Prop Testing Just got done testing a prop with 2 plys BID over a Sensenich Maple wood prop and Scotchcal clear film rain protection on the leading edge. It turned a decent slightly too flat pitch prop into a real dog. TAS down at least 5 knots, and climb to 12,000 much slower. Next week I'll crunch the numbers and report accurate results. I removed the tape, before doing my 3 night landings. Leaving for an overnight campout on Beaver Island in the AM. If anyone wants to join, see you there, at the paved airport. From: cdenk@ix.netcom.com Date: Sun, 12 Jul 1998 19:43:47 -0500 (CDT) Subject: COZY: Prop Testing - Scotchcal Leading Edge Protection. With the generous contribution of the Scotchcal material, I have been able to run comparative flight test of the same propeller with and without Scotchcal clear polyurethane protective tape on the leading edges with no attempt to fair the step at the tape edge. For both flights the prop was freshly refinished with Deltron acrylic urethane 2 or days previously. The tape was installed with approximately 3/8" down both sides, with the tape width about 3/4" to 1". The tape thickness is 0.008". Note that this propeller was selected only because it was available and needs more pitch to be an idea performer on my airframe, and is slower than others I have tested in the last 6 months. CAUTION: 3M warns not to use this material on props, rotors, and balanced surfaces. For climb performance climbs from 2000 ft. to 12,000 ft. @ 100 knots, with 1831 lbs. takeoff weight. THis is probably heavier than most people use. Data taken every 1000 ft. included elapsed time, outside temperature (both flights were near same temps), manifold pressure and RPM. In all cases the altimeter was set to 29.92. The prop with the Scotchcal had 30 FPM. less average climb rate. When putting the data into an Excel spreadsheet, fitting a straightline curve rate vs. altitude, both tests lines were almost perfectly on top each other. For level flight, at 12, 10, 8, 6, 4, and 2000' altitudes, and 2000, 2200, 2400, 2600, and 2700 RPM, Outside temperature, Mainifold pressure and CAS were recorded. This is 30 data points. When averaging the True airspeeds calculated from the CAS the propeller with scotchcal had an average of 8.6 Knots lower. With the freshly painted prop, and tape on 1.8 hours with one takeoff and landing the finish and tape were in perfect condition. The tape was removed, 3 night landings done, and 4 hours of flying including 3 landings the prop was showing battle scars of fine debris on the leading edges and flat surfaces. This is a birch wood prop with 2 plys BID on the blades. When the test flight with tape was complete, I removed the tape, the performance degradation was obvious, without crunching the data, and I didn't want to suffer with the dog any longer. After reducing the data, it supports the initial impression. To date the following conclusions have been drawn: 1: A step up or down near the leading edge as small a .008' (and I don't know how thin of step will cause an issue) will harn the performance. 2: A rough surface created with 600 grit wet paper also causes a similar reduction in performance. 3: Propeller's finish must be kept in top gloss condition for best performance. Date: Tue, 08 Sep 1998 08:57:36 +0200 From: Rego Burger Subject: COZY: Prop Protection? With the latest news of the odd prop damage I have a question to promote thoughts in the line of blade protection. Scenario 1) I have seen some prop designers place a layer of carbon fibre on the rear of their props for added stiffness.... the thought came to mind! !!!!!! ! ???? Is there no impact resistant "fibre" that can be laid up on the front facing face of our pusher props....? Leading edges take some form of blade tape....why can't its area be spread over more surface area to act as a chip guard? Naturally we will never be able to handle a .45 slug hitting the prop but it's those little stones that caused the problems. The ideal would be a form of "rubber like" layer that stuck like crazy. Scenraio 2) On the nosewheel maybe research should be done on tread less tyres....I seem to think the treads "grip" the stones and then "fling" them back like a sling-shot..... this means that a BB sized stone is flying back at a much higher velocity than a bouncing stone being "sucked" up by the prop off the ground... I saw this effect while driving behind a truck one day on a gravel road. Most of the stones just bounced around a few inches off the surface.... while driving on for a while I noticed a "white" patch revolving on one of the rear tyres...mmm... I thought what could that be? well something made me back off, I guess my following distance was a bit close....yep you guessed it that projectile came wizzing over my cars roof luckily! Just picture it ! as the tyre's tread rotates over a stone it picks it up at slow speed, as you're accelerate the forces increase on the circumference eventually releasing that stone at a greater speed. ( anybody have bald tyres for nosewheels? I think the tread is more of a waste on a nose wheel! ) My idea is to remove as many little problems to reduce as many risks as possible... The idea of using the speed brake as a deflector is only good if you have an alternate routing for airflow,(to cool the engine) here too is potential for an innovative design.... when you deploy your speed brake maybe you can have "gills" that open on the side of the cowling for extra cooling? Well that should keep some of you "experimenting" for a while. :-) Rego Burger Web site: http://home.intekom.com/glen/rnb.htm e-mail home- mailto:rnb@intekom.co.za RSA From: "Allan Aaron" Subject: Re: COZY: Prop Protection? Date: Tue, 8 Sep 1998 19:23:42 +1000 No personal experience yet but there is a well respected Long Eze driver around here who swears that by "shaving" the tread off the nose wheel you'll cut down a heck of a lot of debris being thrown into the prop. Australian strips tend to be a bit rougher than typical American airstrips. Allan -----Original Message----- From: Rego Burger To: cozy_builders@canard.com Date: Tuesday, 8 September 1998 17:09 Subject: COZY: Prop Protection? >Scenraio 2) >On the nosewheel maybe research should be done on tread less tyres....I >seem to think the treads "grip" the stones and then "fling" them back >like a sling-shot..... this means that a BB sized stone is flying back >at a much higher velocity than a bouncing stone being "sucked" up by the >prop off the ground... >I saw this effect while driving behind a truck one day on a gravel road. >Most of the stones just bounced around a few inches off the surface.... >while driving on for a while I noticed a "white" patch revolving on one >of the rear tyres...mmm... I thought what could that be? well something >made me back off, I guess my following distance was a bit close....yep >you guessed it that projectile came wizzing over my cars roof luckily! >Just picture it ! as the tyre's tread rotates over a stone it picks it >up at slow speed, as you're accelerate the forces increase on the >circumference eventually releasing that stone at a greater speed. ( >anybody have bald tyres for nosewheels? I think the tread is more of a >waste on a nose wheel! ) Date: Tue, 08 Sep 1998 08:47:00 -0700 From: "LCDR James D. Newman" Subject: COZY: Re: Prop Protection? Hi Rego and All, > With the latest news of the odd prop damage I have a question to promote thoughts in the line of blade protection. > Scenario 1) > I have seen some prop designers place a layer of carbon fibre on the > rear of their props for added stiffness.... the thought came to mind! > !!!!!! ! ???? Is there no impact resistant "fibre" that can be laid up > on the front facing face of our pusher props....? > Leading edges take some form of blade tape....why can't its area be > spread over more surface area to act as a chip guard? Yes there is an impact resistant "fibre" for prop leading edges. WhirlWind Propellor (http://www.concentric.net/~wwpc) has a stainless steel leading edge over their carbon covered 68 ply hardwood prop blades. Their stainless steel leading edges can probably be put onto any prop blade. POC: Jim Rust (619) 562-3725. Infinity's Forever, JD From: "Nat Puffer" Subject: COZY: Prop damage Date: Tue, 8 Sep 1998 09:19:24 -0500 Cozy builders, I previously posted a message that in 20 years of flying canard pushers, there was only one time when I picked up something from a taxiway (and AN3 bolt) that dented my prop, and that I think was when I used a burst of throttle on a dirty taxiway. The airport at Mesa is kept very clean with sweepers on the taxiways and runway inspections quite often. For sure this helps. But Mesa isn't the only place we land and taxi. As a matter of fact, we have been in and out of many different airports all around the country, and even landed and taxied on gravel. I believe the most important factor is to taxi slowly, so as to not throw up anything from the nose wheel, and use the least rpm, so as to not suck up things in the prop. If you aren't thinking about it, it is very easy to taxi at 1000, 1200, or even 1400 rpm and ride the brakes. This will for sure suck up things into the prop. Another good rule is to apply throttle slowly on take off, and not go to full throttle until the airplane is already moving at a good speed. Our airplanes have excellent visibility forward. If the taxiway looks too dirty, you can aways shut down, climb out, and push. Taking good care of your prop is as important as taking good care of your engine, your tires, and your brakes. I believe that if you are ruining props, you are doing something wrong. Regards, Nat From: JohnQue@aol.com Date: Thu, 5 Nov 1998 11:31:27 EST Subject: COZY: Old Unused Prop I have an opportunity to purchase an unused Hoffman composite constant speed prop which has been stored in its original box for over 10 years. Prop was built for an IO360 Long EZ, 72" diam. Has prop technology and design advanced a great degree in these past years? Is a prop stored this long safe? How much work/cost might be involved to inspect and rebalance? Any thoughts would be appreciated. John S Building Berkut From: N11TE@aol.com Date: Thu, 5 Nov 1998 12:14:20 EST Subject: Re: COZY: Old Unused Prop In a message dated 11/5/98 10:34:03 AM CST, JohnQue@aol.com writes: > I have an opportunity to purchase an unused Hoffman composite constant speed > prop which has been stored in its original box for over 10 years. Prop was > built for an IO360 Long EZ, 72" diam. > > Has prop technology and design advanced a great degree in these past years? > > Is a prop stored this long safe? > John, I have recently been given a dealership for Hoffman Propellers to be used on pusher aircraft in the USA. I would be more than happy to forward any of your questions to the factory in Germany for their response. Or, they can be reached by fax (overnight) and I can supply their fax number for you to contact direct. This is how I reach them. Either way, the exact model number and serial number will be needed, along with a little more description. For your information, it is a Hoffman Propeller that was on Tim Merrill's Cozy that won at Oshkosh and was written up in Sport Aviation. I will be installing a three-blade Hoffman Propeller on an IO-540 going into my modified AeroCanard. It is being manufactured as we speak and I expect it to be shipped within the next two weeks. You are welcome to e-mail me for more information or call me at home. Tom Ellis N11TE@aol.com 812-867-2275 Date: Mon, 9 Nov 1998 08:15:40 -0600 Subject: Re: COZY: Old Unused Prop From: mikefly@juno.com (Michael B Bowden) On Thu, 5 Nov 1998 11:31:27 EST JohnQue@aol.com writes: >I have an opportunity to purchase an unused Hoffman composite constant >speed >prop which has been stored in its original box for over 10 years. You would be much better off with a Light Speed prop on your Berkut. Lighter weight and lower complexity are the first considerations. Doubt you would notice much change in performance anyway. Biggest difference is the tremendous drag you would experience when you pull the throttle back. ( speed brake ? ) As for the Hoffman, I've been told that ten years ago,a Hoffman could have been bought for $2500 and they are more than $10,000 now. I do not know how reliable that information is. mbb Date: Mon, 16 Nov 1998 08:38:36 -0500 From: David Domeier Subject: COZY: Prop Report Cozyites, On October 31, I shipped my prop back to Clark Lydick (Performance Propellers) for the final finish. I'd used it about 60 hours and it seemed cut just right - 2360-80 rpm for take off, and 2680 rpm flat out at 8500' Just 12 days later I got it back, via US Mail, would you believe. And I must report it is absolutely gorgeous. Final finish is very smooth (exhaust soot no longer sticks to it), has a black epoxy leading edge, and white tips. For those of you planning on using the Lycoming 180 hp, this prop cut at 64 X 76 works just fine and is very smooth. dd From: CCady@aol.com Date: Mon, 16 Nov 1998 17:41:20 EST Subject: Re: COZY: Performance Prop Report When I ordered my Performance 3-blade the US Mail delivery lady was surprised to be delivering such a unusually shaped item. It almost didn't fit in the back of the small mail truck. When I sent it back for finishing and plunked it on the counter at the local Post Office they were even more surprised. It's a nice prop and the service was pretty good. I didn't see any more speed but it is smoother which is a plus! In a message dated 11/16/98 9:36:55 AM Eastern Standard Time, david010@earthlink.net writes: <> Date: Wed, 02 Dec 1998 20:12:53 -0500 From: John B Vermeylen Subject: COZY: Performance Props When I ordered my Performance 3-blade I had it finished from the get go. I told Clark Lydick that I wanted the same prop that Nat Puffer has. Nat has experimented with many props and I don't think I could do a better job in selecting a better prop cut. So why waste time and money sending the prop back and forth? Johnny V N69CZ Date: Thu, 03 Dec 1998 16:36:52 -0500 From: David Domeier Subject: Re: COZY: Performance Props Johnny, re "When I ordered my Performance 3-blade I had it finished from the get go." Probably a good call. I, too, ordered what Nat is using on his airplane and it was perfect. dd Date: Thu, 3 Dec 1998 08:50:07 -0500 From: Bill Theeringer Subject: COZY: Performance Prop When I ordered my Performance 3-blade I had it finished from the get go. I told Clark Lydick that I wanted the same prop that Nat Puffer has. Nat has experimented with many props and I don't think I could do a better job in selecting a better prop cut. So why waste time and money sending the prop back and forth? Johnny V N69CZ ---------------------------------------------------------------------- John; Because no two airplane/engine combinations are the same. Clark knows that matching the prop to the particular engine and airplane is the optimal way to go. This is why he recommends this service of a final tweak based on your planes actual data. If you purchase a particular prop because Nat or anyone else has had good results with it, that is an excellent bench mark to start from. Ideally the blades should then be opimized for your engines' HP curve and your planes lift/drag/weight envelope. Bill Theeringer N29EZ From: cdenk@ix.netcom.com Date: Thu, 3 Dec 1998 10:16:44 -0600 (CST) Subject: Re: COZY: Performance Prop Was said Everyone should have a spare prop available for instant shipping, when (not if) a stone damages your prop. Its Ok to get the prop if its close performance wise, and then order another that has been adjusted slightly. The prop parameters are as was said a function of many variables including the surface finish of the airframe, attention to airflow details, whether there are wheel pants, etc. The altitude and temperature where you want best performance is critical, and I don't think you will find your preference during the test time. I have had a prop that gave 183K cruise at 5000', and the one I have at the moment (I have another coming shortly) that I can't use full trottle until above 12,000' that at 5000' I run at 23.8" manifold, where I use a cruise limit of 25.5" As far as I know Sensenich is the only manufacturer using a CNC lathe to cut props, and they are able to duplicate or slightly able to adjust accurately. Date: Thu, 17 Dec 1998 20:27:35 -0800 From: Eric Westland Subject: COZY: Prop Question? Well, after waiting much longer than I should have, my 2-blade prop showed up for my Lycoming 200 hp engine. It looks just fine, but when I went to mount it on my 7" extension from Judy Saber, I realized that the prop's hub was slightly undersize, 6.65" in diameter to be precise. So I called the maker and he assured me this was OK. I'm not so sure if it's OK or within the range of acceptability, what do you folks think? I guess I just figured it would be as large (or slightly larger) as the flange and crush plate surfaces. Thanks, Eric Westland From: cdenk@ix.netcom.com Date: Fri, 18 Dec 1998 17:50:55 -0600 (CST) Subject: Re: COZY: Prop Question? Westland wrote The 320 usually has a 6" flange, and the 360 has a 7" flange. While testing props, and remember that the purpose of the testing was to find some design criteria limits. One of the issues became for my 320, 160 hp., the 6" prop hub would occasionaly have a small crack from the bolt nearest the leading edge. Also there were some problems with relative movement of the wood and flange along the perimeter. Increasing the hub diameter to 6.625" eliminated both of these problems. The added wood beyond the flange area apparently gives added support to the wood at the flange. I can't address specifically your issue, but on the 320, details that work fine on a tractor installation are not adequate for a pusher. I know on the 360, Sensenich provides a 7" hub, for myself, I would not want less. Date: Sat, 19 Dec 1998 15:15:09 -0500 From: Dave Black Subject: COZY: Re: [canard-aviators] Prop Question? Eric, > I realized that the > prop's hub was slightly undersize, 6.65" in diameter to be precise. So > I called the maker and he assured me this was OK. I'm not so sure if > it's OK or within the range of acceptability, what do you folks think? > I guess I just figured it would be as large (or slightly larger) as the > flange and crush plate surfaces. I'm not sure what the range is supposed to be, but the prop should fit TIGHTLY around the flange. It must be that way to maintain proper prop centering. You should be able to force the prop in place by hand, or by employing moderate, protected taps from a hammer. Good luck, Dave Black Velocity RG From: cdenk@ix.netcom.com Date: Sat, 19 Dec 1998 16:11:27 -0600 (CST) Subject: Re: COZY: Re: [canard-aviators] Prop Question? A few definitions first: Flange diameter: The large diameter of aluminum directly in contact with the prop on the engine side. Propeller only contacts flat surface, not the outer diameter. Hub: The roughly 1/2" high projection away from the engine on the flange. Not used to center wood props, or possibly any. Although the prop may have a center hole that matches the hub, thats not what locates it. Lugs: The 5/8" (usually) diameter tubular inserts at each bolt that project out of the flange away from the engine. Preferably have a shoulder on the engine side of the flange and internally threaded for the prop bolts. These locate the propeller to center it on the crank centerline. The lugs DO NOT normally drive the propeller in rotating. Friction from the tight bolts only rotates the propeller. If the bolts should loosen, the lugs will turn the propeller for a short period of time. Loose bolts on a wood propeller will create enough friction to char or burn (boyscout rubbing 2 sticks to make fire like) the prop. On a tractor installation, they tell me you can smell the burning wood. I have while testing propellers, exploring bolt torque requirements, have had the flange surface of the prop char a small amount. Some other prop installations use tapered mounting, etc. Thats not what we usually have and is a whole different situation. From: "Cy Galley" Subject: Re: COZY: Re: [canard-aviators] Prop Question? Date: Sat, 19 Dec 1998 22:17:15 -0600 -----Original Message----- From: cdenk@ix.netcom.com To: asterisk@EROLS.COM ; ewestland@altavista.net ; canard-aviators@canard.com ; cozy_builders@canard.com Date: Saturday, December 19, 1998 9:43 PM Subject: Re: COZY: Re: [canard-aviators] Prop Question? >Hub: The roughly ½" high projection away from the engine on the flange. >Not used to center wood props, or possibly any. Although the prop may >have a center hole that matches the hub that's not what locates it. So what locates the prop on center of the hub? ???? I think that this information is wrong. The hub is centered on the hub by that hub as it is called the centering hub. On a metal prop, the fit is so snug that a little corrosion makes the prop hard to get off. A well made wood prop also is centered by this hub. If you have ever carved a prop, many times the prop is rotated 180 degrees to route the second blade. It is rotated and laid out around this "centering hole." When you take a prop to a prop shop, everything is checked from this center hole... But you say that is not what it is for??? How and what centers the prop? The drive lugs? they aren't on the center so they can't be used to center the prop. I must have missed something in my 30 years of repairing airplanes. Cy Galley, Chairman - Emergency Aircraft Repair, Oshkosh From: cdenk@ix.netcom.com Date: Mon, 21 Dec 1998 14:40:57 -0600 (CST) Subject: COZY: Prop Center This got returned as mail failure, I am resending: Cy Galley writes I am talking only of wood props, and only those commonly found on Ez's!! My information is based on that I learned from Sensenich Wood Propeller testing I did. For their props, and I don't think there is a more experienced organization in existence. When mounted on the flange, its the dowels that locate the prop on the crankshaft centerline. Their center hole is also concentric and is used for balancing. I have had considerable discussion with Sensenich on balancing, where it only takes a few thousands of an inch excentricity to throw off the balance. They have assured me to use the center hole. I would prefer to use the dowel holes, but to have an arbor made now is not in my budget. From: "Diane Carlton" Subject: COZY: Prop Question!! Date: Mon, 21 Dec 1998 16:29:23 -0500
Does anyone have spec.'s on a two blade prop for a Cozy MK IV with an IO-360 to share?  I plan to get a two blade prop as a spare that I will use to fly off my hours.  If not an IO-360, give me spec.'s for the O-360 too which shouldn't be that much different in length.
 
Thanks,
 
E.J.