From: lschuler@cellular.uscc.com Date: Tue, 13 Jan 98 15:21:02 -0600 Subject: COZY: Chapter 12 Hi all. H___E___L___P ! Waiting on some parts to start building the elevators, I took the opportunity of time to set my newly finished canard in the fuselage just to see how it looks. Snarky, but Big dissapointment! I screwd up somewhere.... Did not do any leveling or attempt incidence, but looks like I have roughly 0.2" gap between the lift tabs and F22 wth the canard Trailing edge butted against the bottom of F28 and fuselage sides (below the longeron doublers). Ouch! I read the archives, Marc's log, etc. but didn't see much about this problem (makes me feel like the lone idiot). Marc added 10 plies BID on one side of F22 to get square with the firewall. This indicates that additional layups on front of F22 is probably do-able and suggested in plans, but 0.2" seems like a lot. Checked everthing I could think of to find source of the trouble and possible fix ideas. Here's what I have: Using a Rube Goldburg setup with two squares, my canard measures roughly 6.15" from the rear of the lift tabs to the trailing edge. Measuring the templates and adding in the shearweb and hard-point layups results in about 6.125"; can't complain about what I got. Fairly close to the templates. Chapter 6, Page 1, Figure 3 shows 5.9" measured from the rear of F22 to the rear of F28; but doesn't indicate wheather that is taken at the center of the bulkheads or at the fuselage. There is a significant diference caused by reinforcements on F22 at the sides). I wouldn't have a problem if this measurement is intended at the fuselage side. However, this figure is not referenced in the text for F28 installation. Chapter 6, Page 2, Figure 9 shows 5.9" measured from the front of F22 to the front of F28; This figure is also refered to in the text at the point where F28 is instaled. This is what I used and exactly what I have now. Drawing M-11 (supposedly a full size drawing, which is also used to plot the shape of the nose etc) shows the front of F22 to the front of F28 to be 6.1". It also shows the distance from the front of F22 to the canard TE to about be 5.95" Drawing M-11 also shows the distance from the rear of F22 to the rear of F28 to be 5.75". I measured 5.4" near the fuselage on mine (this would be 'with' the reinforcement layups. The above obviously points to some errors in the plans, but doesn't help with a fix unless I missed something.... I'd like some suggestions as to a fix, particularly from those who have passed this point and even done the canard cover etc. Here's some possibles; if there is one I missed, please add to the list: 1. Scrap the canard and reduce the cord to that on M-11. Screws up the aerodynamics to be sure. 2. Add BID layers or plywood and BID on the front of F22 to take up the gap. Changes the lever arm of the forces on F22. Also moves the distance from the wing to canard forward about 0.2" which may result in too much lift from canard (easier to deep stall). 3. Cut out F28 and reinstal/replace it 0.2" further back. Do-able, but the outside of the fuselage has already been shaped and glassed, including top longeron shaping/glassing. 4. Cut 0.2" notchs in the fuselage sides (vertical area of the canard cut out) to accomodate the TE. Do-able, but creates a significant weak spot in the fuselage below the top longerons. Could add a couple plies of BID around this inside and out, but not sure of the resulting strength and makes finishing the outside more interesting. 5. Trim 0.2" off the canard TE between the fuselage sides only. In my case, this leaves about 0.3" or maybe a bit less glass-glass contact area on the TE. Do-able, but may weaken the torsional load capability of the canard too much and unknown amount. Thanks for any help or suggestions. Larry Schuler MK-IV #500 Disheartend temporarily in Wisconsin lschuler@cellular.uscc.com From: Marc J. Zeitlin Subject: COZY: Chapter 12 (fwd) Date: Tue, 13 Jan 98 17:17:00 EST Larry Schuler wrote; > ...... Did not do any leveling or attempt incidence, but > looks like I have roughly 0.2" gap between the lift tabs and F22 wth > the canard Trailing edge butted against the bottom of F28 and fuselage > sides (below the longeron doublers). Ouch! > 1. Scrap the canard...... No, no, no, no, no. > 2. Add BID layers or plywood and BID........ Nah. > 3. Cut out F28 and reinstal/replace it 0.2" further back. Uh uh. > 4. Cut 0.2" notchs in the fuselage sides........ > 5. Trim 0.2" off the canard TE between the fuselage sides only. > In my case, this leaves about 0.3" or maybe a bit less glass-glass > contact area on the TE. I'd go with a combination of 4 and 5. It's not clear on my web pages, and I didn't mention it, but I did have a SLIGHT interference like yours when installing my canard - I figured it was just one of those tolerance things again :-). For me, it was about 1/8" at the most. I would: 1) Trim 0.1" from the canard T.E., leaving at least 3/8" of G/G bond. 2) Gradually taper the fuselage sides back below the longeron about 1/8", to leave a small space between the T.E. of the canard and the fuselage sides (you need room for 1 BID and filler and paint and you'll have to futz with this area anyway when you get your elevators installed, to clear the torque tubes closely with a seal). 3) Add BID pads as required on F22 to level/align the canard to the fuselage (per plans). The canard is held on by the lift tabs on F22 (that's one reason why they're at the shear web - it's near the center of lift) - the F28 pins are for alignment and aerodynamic moment reaction forces. You won't significantly reduce the strength of the fuselage by a smooth taper of 1/8" in the F28 area, and the canard cover/elevator fairing can easily deal with this aesthetically. You'll be fine. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Tue, 13 Jan 1998 16:40:33 -0600 From: Darren DeLoach Subject: Re: COZY: Chapter 12 > Chapter 6, Page 1, Figure 3 shows 5.9" measured from the rear of > F22 to the rear of F28; but doesn't indicate wheather that is taken at > the center of the bulkheads or at the fuselage. There is a > significant diference caused by reinforcements on F22 at the sides). > I wouldn't have a problem if this measurement is intended at the > fuselage side. However, this figure is not referenced in the text for > F28 installation. > > Chapter 6, Page 2, Figure 9 shows 5.9" measured from the front of > F22 to the front of F28; This figure is also refered to in the text > at the point where F28 is instaled. This is what I used and exactly > what I have now. > > Drawing M-11 (supposedly a full size drawing, which is also used to > plot the shape of the nose etc) shows the front of F22 to the front of > F28 to be 6.1". It also shows the distance from the front of F22 to > the canard TE to about be 5.95" > > Drawing M-11 also shows the distance from the rear of F22 to the > rear of F28 to be 5.75". I measured 5.4" near the fuselage on mine > (this would be 'with' the reinforcement layups. > > The above obviously points to some errors in the plans, but doesn't > help with a fix unless I missed something.... > As someone who is about to piece my fuselage together, what is the right thing to do here: should I consider putting my F28 6.0 or even 6.1" back instead of 5.9" so I won't have this problem? Is it better for F28 to be a little too far back than too far forward? How many folks who got that far had the same problem? -- Darren DeLoach Sales & Software http://www.deloach.com From: cdenk@ix.netcom.com Date: Tue, 13 Jan 1998 18:27:14 -0600 (CST) Subject: Re: COZY: Chapter 12 (fwd) Larry Schuler wrote The torsion loading of the canard will be most at the tabs, and possibly only somewhat less between the tabs. One of the functions of the glass to glass is transfer the torsional shearing stresses around the corner from top to bottom and vice versa. Therefore the glass to glass dimension near midspan should not be less than the quality control numbers. Date: Tue, 13 Jan 1998 23:20:24 -0500 From: "Jeff S. Russell http://www.AeroCad.com" Subject: Re: COZY: Chapter 12 lschuler@cellular.uscc.com wrote: > > Hi all. H___E___L___P ! This problem is from the large M drawings and the plans giving a wrong 5.9 dimemsion. I called Nat in 1992 about this. He took the M drawing that shows the canard in the nose of the MKIV and checked the measurements of the canard templates. All he could remember on what he did on his airplane was shim the lift tab location on F22 with BID and cut some of the trailing edge off the canard. I have moved our location of F28 to 6.25 and have never had a builder have this problem. The offsets are also too close together. The 1" tube between them should be about .25 to .375 longer to take care of that problem of them hitting the side of the fuselage. -- Jeff Russell/AeroCad Inc. E-mail: Jeff@aerocad.com P.O. Box 7307 Port St. Lucie FL. 34985 Shop# 561-460-8020 Home# 561-343-7366 Composite workshop info: http://www.Sportair.com Date: Mon, 12 Jan 98 9:12:54 EST From: "Nick J Ugolini" Subject: COZY: Canard Incidence If you read the last Cozy newsletter you read a little about my canard incidence problem. I though I would post my letter to Nat in case he does not publish it. I think my experiences would be of benefit to the group. Nat has been a pleasure to work with everytime I contacted him. He took great pains explaining why my plane was unsafe to fly (in its former condition). I thought you might be interested in my correspondence with him. I am excited about having Nat on our email group as his experience will be a great benefit to all. >12/24/97 Dear Nat, As promised I am writing a letter detailing the canard problems with my LongEZ, N29TM. Problem: A soft spot on was found on the canard found during the 100 hr inspection. The tap test indicated delaminated of the foam, approximately 2" by 3". I decided to drill a hole in a the canard for epoxy injection. After drilling a few holes I discovered there was no foam in the canard! I immediately cut the bottom of the canard open and found an area about 2" by 10", from the bottom to the top skin between the spar and the leading edge where the foam had been dissolved by a solvent into a =BD" layer of goo. The previous owner had repainted the canard, and must of wiped it with solvent. Big mistake. The repairs were basic, replace the foam, re-glass. During the rebuilding process, I made canard templates to check my work. When I reinstalled the canard, I checked the incidence angle. Much to my surprise, I found the left side down 2 =BD deg and the right side down 1 deg as referenced from the longerons. I also found the longeron to be 1 deg down in the fully loaded plane configuration. These measurement explained some problems I have been having. 1. Long take off rolls: Overall canard incidence was down, gear legs too long. At times I had to bounce the nose to cause rotation. 2. Airplane rolling to the left: Left canard incidence down, more than right canard, necessitating shimming the right rudder. 3. Elevator trailing edge down 7-10 deg. This necessitated lots of trim and high stick forces at low speeds. I had to fly at least 130 kts before the trim adjustment had any effect. Causes: I think the canard must of twisted during the post cure, maybe years later. The construction indicated proper overall alignment of the canard (but with a 1 deg down incidence). I believe the gear legs were built to the proper length, BUT in trying to get the nose wheel to fully retract, the builder reduced the amount of extension of the nose wheel which changed the angle of the plane. Solutions: I used my GU canard templates to reshape the upper surface of the left canard to match the angle of incidence the right canard (effectively making the left canard thicker). I used a FAA approved procedure in the Central States Newsletters for changing the overall canard incidence. I also cut 1 =BD" off the gear legs. Results: The plane now trims out at all speeds with very light stick forces. The trailing edge of the elevator is 0 deg at low speeds and 2 deg up at high speeds. Stall speed of the canard is 59 kts. I was able to take out most of the right rudder shims. The plane takes off easily at all weight loading. Recommendations: After you build your plane carefully check all critical measurements or angles to ensure they have not changed in the building process. After a few years of use, reevaluate your plane again to ensure age/creep/post curing has not affected your plane. If you ensure your plane is built and stays within the tolerances of the plans, its performance will be predictable and safe. Thanks for your help Nat. I am sure I would not have looked as closely into my plane problems without your insistence, assistance and guidance. Nick< >>Dear Nick, Thank you for your report. I don't believe the problem you described could have been caused by post curing. Once the wing or canard is glassed on both sides, it would be almost impossible to twist it. More likely it was just a case of lousey building. Glad you discovered all of these problems and were able to correct them--particularly the canard incidence wrong, because that was dangerous. Glad the airplane flys well now. Take care, Nat<< Date: Tue, 13 Jan 1998 08:33:33 +0200 From: Rego Burger Subject: COZY: Canard incidence Thanks Nick for your true story. My discovery. After making the correction to the TEMPLATE I found my canard sitting with negative incidence. Ouch! Where I went wrong: The natural norm of building things (to me) is to work with level lines. So I made a nice jig that simply fitted with nails onto the profile of the canard during primary fitting. HOWEVER , if I now take the TEMPLATE ( corrected one ) and place it on top of the canard OOPS! By superimposing the template on top of the canard aerofoil I measure 1/8" difference at the L.E. to the T.E. between the top of the template and the level line. THEREFORE the level line on the canard would be 1/8" positive to airflow. I feel the aerofoil template should be redrawn with a corrected level line TOO! Thanks to Nat for the caution , and J.D. Newman for his patience enduring all my questions on the subject a group like this shows many with skills of "teaching ability" etc. Rego Burger, web site: http://home.intekom.com/glen/rnb.htm (home e-mail) mailto:rnb@intekom.co.za Date: Wed, 14 Jan 1998 07:44:22 +0200 From: Rego Burger Subject: Re: COZY: Canard incidence!!!!!!!! -repair Hello, Rego Burger, web site: http://home.intekom.com/glen/rnb.htm (home e-mail) mailto:rnb@intekom.co.za >>> Gunrider 13/January/1998 06:26pm >>> I assumed a level line is a level line. What do I have to do to fix the problem???- I finished that months ago. I missed the first discussion on this subject. Am I in big trouble? Hugh Farrior Puttin' in the spar. Yep, I'm not sure if you're the same "gunrider" I spoke to some years back...? :-) Trouble... just a tad. To Fix..... You need to do what I'm busy doing... a.) Make the corrected template and re measure with longerons level and the top of the template level. b.) Sand the fuselage sides down a bit (under rear of canard ) to accommodate a lowering of up to 1/8". c.) Ream or elongate the "pin"locator holes to allow them to lower sufficiently...only once satisfied they're correct Flox in place. Have not started yet but that's my plan of action. From: "Johnson, Phillip" Subject: COZY: Canard Incidence Date: Wed, 14 Jan 1998 10:49:42 -0500 I've been very busy recently and have not been paying too much attention to the posts of this mailing list however the one regarding canard incidence has caught my eye and given me cause for concern. I received an updated canard incidence template, from Nat, a long time ago and my canard was spot on. But I think that I used the water line to define the reference as you would expect. The recent posts indicate that there is an error on this updated template. Is this correct? Has Nat agreed that there is an error and posted a correction that I have missed? Can someone please clarify in words of one syllable. Thanks ------------------------------------------------------------------------ ------------------------------------------------------------------------ --------------------- Phillip Johnson Ottawa, Ontario, Canada. Tel (613) 253 2229 (H) (613) 599 3289 ext. 441 or 232 Cozy MKIV RG #30 Subaru EG33 ------------------------------------------------------------------------ ------------------------------------------------------------------------ --------------------- From: lschuler@cellular.uscc.com Date: Wed, 14 Jan 98 11:40:42 -0600 Subject: COZY: Canard Incidence --simple boundary Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Description: "cc:Mail Note Part" Hi Phillip, Long time no post. :-) I havn't heard about 'another' incidence change or correction. The only one of record (unless I missed one too) was that the 'F' and 'G' template level lines don't match and that "G" is the correct one to use. The "F" template level line needs to be corrected to match "G". I think one of Rego's friends is having some dificlulty and another fellow had purchased a plane and found incidence and squareness with firewall a bit off(along with a few other odds 'n ends like solvent in the canard foam). You should have received a special mailing from Nat on the 'F'/'G' issue several months back. If not, I can fax you a copy. Hope that helps. Hope you folks fair well in the ice storm. Larry Date: Thu, 15 Jan 1998 07:46:39 +0200 From: Rego Burger Subject: COZY: CANARD INCIDENCE EXPANDED Let me give you ALL the background. I made contact with Nat on a few points and one of them was the canard incidence. As much as I know one must follow plans any average or above average thinker will come up with some other way of alignment procedures. Some folks use laser sights others use digital spirit levels etc. etc. Then comes the question of References! I made a simple ( so I thought ) jig that could be "nailed" into the foam on the level line during my initial setting up of the canard...in mentioning this to Nat. He knowing what he was doing informed me that the level line was indeed NOT LEVEL in the true sense of the word or if my memory is correct it was level for a Long-Eze. Since then I went back and made up the corrected template and as mentioned recently superimposed it on top of the aerofoil and found it not to be parallel but in effect 1/8" positive ( the level line ie.) so if you used the level line to line up then the canard is 1/8" negative to the relative airflow! My opinion on the solution would be to publish a correction of the level line too for fear of many not using the template as per plan and working on the level line! Hope I'm clear but will gladly discuss at length off line not to clutter the forum with folks who may struggle like I did to understand the whole thing. I have thanked others who helped me clear it up so this is a team effort thanks to Marcs forum. Rego Burger, web site: http://home.intekom.com/glen/rnb.htm (home e-mail) mailto:rnb@intekom.co.za Date: Thu, 15 Jan 1998 07:18:35 -0500 From: "Jeff S. Russell http://www.AeroCad.com" Subject: Re: COZY: CANARD INCIDENCE Rego Burger wrote: > My opinion on the solution would be to publish a correction of the level > line too for fear of many not using the template as per plan and working > on the level line! When cutting the cores, you make a water level line to set the hotwire temps. After the cores are cut, you use a template that shows the same water line. If you change the water line on this template, the core line and temps will not be the same. The mounting template should be the correct one to make different. Less confusion :-) This was the one that also had the elevator travel with it. Hope that helps -- Jeff Russell/AeroCad Inc. E-mail: Jeff@aerocad.com P.O. Box 7307 Port St. Lucie FL. 34985 Shop# 561-460-8020 Home# 561-343-7366 Composite workshop info: http://www.Sportair.com Date: Thu, 15 Jan 1998 14:57:03 +0200 From: Rego Burger Subject: COZY: CANARD INCIDENCE-REPLY >>>>>> Jeff Russell wrote, When cutting the cores, you make a water level line to set the hotwire temps. After the cores are cut, you use a template that shows the same water line. If you change the water line on this template, the core line and temps will not be the same. The mounting template should be the correct one to make different. Less confusion :-)<<<<<<<<< This is what I want to clear up: What you have done now is defined what we now know...that the "level line" was being used for the cutting reference out of the foam blocks, however the TERM is enough to make the average person familiar with the english language think this to be an aerodynamic level line also. On an item as serious as the canard it is worth talking about. By changing it by the correct amount what I see as about 1/8" will not effect the foam cutting unless the foam block is too small. Logic says Level is level. Now that I know what's happening I'm happy, it's the others who may have made the same mistake as I and NOT having rectified it that I wish to caution. What I would do to avoid the confusion. Two options: 1.) Rename the line to say to "HOT WIRE REF.ONLY"( and leave it so ) 2.) Adjust it to the REAL level line and both can be used for setting incidence. In "normal" circumstances Level implies just that Level... Level line -3 is accepted as 3" below the zero ref. Line being an angle of 180deg means it must stay level through to infinity. So a level line at zero and -3 should never intersect. Naturally it's up to Nat to decide if it's important. This type of ambiguity would make a the O.J. case look like a lunch break. :-) Thanks for the contribution. The more we discuss the more we will understand. Rego Burger, web site: http://home.intekom.com/glen/rnb.htm (home e-mail) mailto:rnb@intekom.co.za From: lschuler@cellular.uscc.com Date: Thu, 15 Jan 98 14:36:46 -0600 Subject: Re: COZY: CANARD INCIDENCE EXPANDED Rego wrote: >snip >Hope I'm clear but will gladly discuss at length off line not to clutter >the forum with folks who may struggle like I did to understand the whole >thing. I have thanked others who helped me clear it up so this is a team >effort thanks to Marcs forum. Rego, Maybe we should keep it 'on-line'. This is exactly what the list is all about; we may all benefit. Every time a discussion like this goes one-on-one, the rest of us suffer. We ALL make boo-boos and can each benefit from others' boo-boos. I've made some and said so here; won't be the last either. Group-hug...... warm fuzzy time. :-) Sounds like you used the hot-wire templates nailed to your canard for setting incidence. Oops. The hot-wire template level lines have nothing to do with aerodynamics and may or may not be referenced to the true cord of the airfoil, it's angle of attack, or anything else that is important to flight. I believe they only need to be exactly the same on each end when hot-wiring; and, the sole purpose is to ensure there is no twist in the canard. They are used to match the templates for cutting foam only. Thinking about that, it really won't matter where the lines are drawn on them as long as both templates (each end of the canard) are "identical". You could disreguard the lines on the hot-wire template drawings and make your own to suit yourself. They would still work as long as both ends are nailed on for cutting without twist. If you want to nail hot-wire templates on after construction and use them to set the canard incidence, then the incidence-setting level line (top of) the "G" template would need to be transfered to the hot-wire templates in order to be accurate. In order to use the top of the "G" template for setting the incidence, then the top of the "G" template "MUST" be dead parallel to the airfoil's true cord line. The airfoil cord line is how angle of attack/incidence are determined aerodynamically (unless Nat did something wierd, which isn't likely since he isn't an aeronautical engineer). To find the airfoil cord on the hot-wire templates using "G" template as a guide: find the "exact" apex of the "fully glassed" leading edge radius (good luck; especially on the hot wire templates with their bottom indent for glass overlap) and draw a line back to the tail making sure the line is 'exactly' parallel to the top of the "G" template. If that doesn't produse the true airfoil cord line, then either Nat or Roncz did something strange... Roncz might (he does stuff like that sometimes), but I doubt it in this case. Better yet, don't use the hot wire templates except for hot-wiring or for pulling a string line across the canard using the hot-wire call numbers for locating guides. Does that help? Larry Schuler #500 lschuler@cellular.uscc.com Date: Fri, 16 Jan 1998 07:42:55 +0200 From: Rego Burger Subject: Re: COZY: CANARD INCIDENCE EXPANDED -Reply Larry wrote: >>>>The hot-wire template level lines have nothing to do with aerodynamics and may or may not be referenced to the true cord of the airfoil, it's angle of attack, or anything else that is important to flight. <<<<<<<<< Yep this is what some of us are concerned about, Logic would think that if a designer marks water lines or level lines on templates they are indeed aerodynamic references too! Why use two norms or references? If I look at the wings the W.L. stays horizontal but you can see the airfoil twists out to the tip (washout), again I hereby assume that Level is the Level, now only Nat will know if he changed that. Is he on the Group yet? WHY is the longeron refered to as a W.L. if it is not level? etc..etc. In my humble opion a template that fits on top of an airfoil should have it's Level line 100% parralel with the W.L. If this is not std practise then what is std.? I have no problem with a group posting but some folks who don't want to show their difficulty in understanding are free to e-mail me direct. Rego Burger, web site: http://home.intekom.com/glen/rnb.htm (home e-mail) mailto:rnb@intekom.co.za From: lschuler@cellular.uscc.com Date: Fri, 16 Jan 98 07:59:29 -0600 Subject: Re: COZY: CANARD INCIDENCE EXPANDED Phillip Johnson wrote: >OK Larry, >I liked your post and it has set my mind to rest re the canard. Now what >about the main wings? Do the level lines really mean level in this >instance? Sorry Phillip, I am still futzing around at chapter 10/11 (canard/elevator. I havn't gotten to the wings yet (wish I was there). If there is a separate jig/template for wing incidence you can rest assured the hot-wire templates shouln't be used unless true cord line is identified on them and matched parallel to the jig/template. If there is no separate jig/template for the wing incidence and plans refer to the hot-wire templates for incidence-setting (which I don't know about yet), then the hot-wire 'level' lines "Must" be true cord. Assuming Nat didn't do something strange. Isn't there a twist required in the wing? If so, the outboard hot-wire level lines will deffinitely NOT be true cord, but a number of degrees offset from the inboard line in order to set twist. Not having 'studied' that far ahead, I know little of how the wings are done.... Principal of incidence vs true cord is same though. Larry Schuler MK-IV plans #500 lschuler@cellular.uscc.com Date: Fri, 16 Jan 1998 09:23:16 -0500 From: David Domeier Subject: Re: COZY: CANARD INCIDENCE EXPANDED -Reply Rego, re "Level is the Level, now only Nat will know if he changed that. Is he on the Group yet?" The MKIV plan is a copy of the LEZ plan almost word for word. The difference is the size of the airplane. I my memory serves me correct, the Water Line in the LEZ was just that - THE LEVEL LINE for the entire airplane. It is my impression that the angle of incidence of the MKIV canard (a Ronse canard as opposed to GU canard on the LEZ) was increased slightly to make it stall sooner. That's why the MKIV canard WL is no longer the real level line for it. And that was not a recent change. It was published that way but when guys noticed a difference in water lines between the canard template and the incidence checker, Nat had to clarify the issue. This is my impression of the issue and has been since day one. If I am wrong, then someone explain it again. dd From: lschuler@cellular.uscc.com Date: Fri, 16 Jan 98 11:43:12 -0600 Subject: Re[2]: COZY: CANARD INCIDENCE EXPANDED -Reply Rego Burger wrote: >Yep this is what some of us are concerned about, Logic would think that >if a designer marks water lines or level lines on templates they are >indeed aerodynamic references too! Why use two norms or references? Totally depends on the "Purpose" and point of reference of the line, mark, measurement, level point, shape, and so on. Why attempt to state a measurement from the fuselage side to the canard tip if it isn't useful for anything? The "useful" reference for canard length is both it's center line and the fuselage center line. Lets see if this extreem example is of help: Take the tail of the canard hot-wire templates. They have a specific dimension, shape etc. and the particular location of the top surface of the tail "could" be measured precicely referenced to a horizontal line on the template, say for example, the true aerodynamic cord line. B_U_T, that tail has absolutly nothing to do with aerodynamics; it gets chopped off. It's sole purpose in life is to provide a firm base for laying up the bottom skin. Do-able, sure; but, why go to the trouble? Same kind of idea on the hot-wire template lines used for cutting foam. That is their sole purpose in life; to cut foam accurately. The only reason they are called 'level' lines is so that you use a 'level' to ensure they are 'both' referenced to earth 'level' so there is no twist. The center of the earth (gravity) 'level' in this case is the reference point, not the cord or aerodynamics. The lines "could" be the same as the true cord and aerodynamics, but for the "purpose" they are intended for, they don't need to be. Always comes back to "purpose". Why go to the trouble to reference the aerodynamic cord, if it is necessary? Clear as mud; right? >If I look at the wings the W.L. stays horizontal but you can see the >airfoil twists out to the tip (washout), again I hereby assume that >Level is the Level, now only Nat will know if he changed that. Is he >on the Group yet? Rego, I think part of your problem is hidden in your words above. One word kind of sticks out; same word absolutely ALWAYS gets me into trouble too, so don't feel bad. The word is "assume". Not a good thing. Let's see if I can help with the W.L. idea. "ALL" water line marks and measurements are referenced to an imaginary plane located under the fuselage. The "ONLY" time you would ever be able to measure to/from it is when you are installing the bulkheads. At one point during that process, measurements were made from points on the fuselage vertically down to your workbench (or 2 X 6 if that's the way you did it). The workbench/or 2 X 6 was W.L. 0 (zero) and needed to be dead flat and level. Once the flox set on your bulkheads/fuselage sides, that measurement (W.L.-0) was set in stone, so to speak. However, after the fuselage sides with bulkheads was removed from those jigs, the W.L. 0 (zero) reference again becomes totally imaginary and there is no "physical" location where WL-0 (zero) will appear physically again (at least until the gear are on). The top logerons were installed in such a manner that they were supposed to be dead flat, parallel, and level with your "physical" W.L. 0 (zero) reference and the earth. Therefore it follows that the top longerons can now and forever be used as solid "physical" references with respect to everything else on the airplane. Now combining the WL-0 plane (either imaginary, or as referenced to top longerons) with the idea of the "purpose" of the wing hot-wire templates: As you noted, the wing has a twist with respect to the waterline "plane". That's correct. However, the lines on the hot-wire templates may or may not be referenced to the water line plane or true cord line. They certainly don't need to be. The twist is produced by making the 'level' lines on the hot wire templates diferent ONLY "with respect to one another". The relationship of these lines, as on the canard, "might" have nothing to do with true cord or a water line. This would depend on the designer's intended "purpose" of the templates after the foam is cut. I havn't cut my wings yet, so am not sure here, but would wager that the angular difference of the lines on each template from root to tip are referenced to a line drawn on the root template and not to any other real or imaginary line; including the longerons. The root hot-wire template line, in this case, could certainly be arbitrary and not necessarily be related to the true cord of the wing root or cord of any other wing section. For the "purpose" of hot-wiring the cores, the angular difference in the 'level' lines would only need to be referenced to an imaginary plane running through the root template 'level' line. You could use vertical or near-vertical lines on the hot-wire templates just as easily as more horizontal ones for the "purpose" of cutting foam. Sure be hard to confuse vertical lines with cord or water lines wouldn't it. Problem then is the shortness of the lines... The true cord of the wing root (not necessarily the hot-wire template line) MUST be referenced to "A" waterline plane in order to set the appropriate angular incidence of the wing. The top longerons are generally set as your reference plane and these are referenced to the imaginary WL-0 whaich was establishe in chapter 6. >WHY is the longeron refered to as a W.L. if it is not level? etc..etc. See above. The top longerons are, and always will be, reference points for both leveling/squaring other stuff on the airplane [IF] you set them properly level and parallel to W.L. 0(zero) when floxing the bulkheads and fuselage sides together. Now, just to throw you off a bit. What if the fuselage is tilted nose down in a 32.9564 degree angle (pick an angle). What happens to the Water Line reference plane? STILL THERE. It moved with the fuselage and can still be referenced to the top longerons. It just isn't level with the earth any more. WL-0 in this case is now exactly 32.9564 degrees off true level. More mud. >In my humble opion a template that fits on top of an airfoil should have >it's Level line 100% parralel with the W.L. >If this is not std practise then what is std.? Sorry Rego. Another fatal word: "should". Again, don't feel bad; I say the same darn thing when I start swearing at Nat and Rutan both for doing stuff the way they did. If we all did the design work, then others would be swearing at us; saying: we 'soulda' done this, or 'shoulda' done that. I can agree with you, in general; with some however's: 1. Gotta remember the "purpose" of said template. If it wasn't intended for such use, then don't expect it to work that way. 2. Must know what the designer is referencing or comparing. The reference may not always be apparent. Such as the hot-wire templates: the reference is only to each end, and not necessarily to anything else measurable on the airplane. 3. Totally dependant on the need for twist and angle of attack at any particular point along the span of the airfoil (canard, wing, winglet). Good example is the "G" canard template. The top of said tempalte must be dead level with the earth when the top longerons are dead level with the earth; and, this MUST be true from the fuselage to the canard tip to ensure there is NO twist. When those conditions are true, the parallel reference is still W.L -0 (zero), the top longerons or any other "parallel" plane [either real or imaginary] as measured from the top of the template. My opinion may not be the 'righest' one (may be tottaly wet); so, caution. >I have no problem with a group posting but some folks who don't want to >show their difficulty in understanding are free to e-mail me direct. The dumbest question I ever heard of was the one NOT asked that can kill ya. Dumbest fellow I ever met was the fellow who knew everything and never figured out how to say the words: "I DON'T KNOW". Wisest fellow I ever met said: "I don't know" a lot more than I do.... Larry Schuler lschuler@cellular.uscc.com From: lschuler@cellular.uscc.com Date: Mon, 02 Feb 98 08:44:36 -0600 Subject: COZY: Re[2]: Chapter 12 Thanks for the suggestion Nat. Hopefully you will be looking at the plans. There is a bug in there somewhere. I followed them to the letter. An easy plans fix would be moving F28 rearward 0.25" in figure(s) I refered to below. There is plenty of longeron doubler to take this change and the design lift-point distance to main wing would not change. Also would allow a bit of wiggle room for squaring the canard to the center line. Would also allow a bit of space for the BID on the fuselage edge which is called out later. Hope this helps others. Larry ______________________________ Reply Separator _________________________________ Subject: Re: Chapter 12 Author: "Nat Puffer" at Internet Date: 1/31/98 11:50 AM Dear Larry, Sorry for my delay in answering. I think a few other builders may have encountered the same problem. I suggest that you notch the trailing edge where the interference is. You will be adding additional layers of glass outboard of that point when you install the incidence tabs and over over the canard. If you do not wish to cut the entire amount away from the TE, you could also add about .1" to F22. It would make that area stronger. Best regards, Nat ---------- > From: lschuler@cellular.uscc.com > To: NatP@cozyaircraft.com > Subject: Chapter 12 > Date: Tuesday, January 13, 1998 4:04 PM > > > Nat, > > Heard you will be joining us on Marc's E-mail list. Great! > > Here is a copy of a note I just sent out today. Got a bug in canard > area and need some ideas. > > Thanks, > > Larry > > > > Hi all. H___E___L___P ! > > Waiting on some parts to start building the elevators, I took the > opportunity of time to set my newly finished canard in the fuselage > just to see how it looks. Snarky, but Big dissapointment! I screwd > up somewhere.... Did not do any leveling or attempt incidence, but > looks like I have roughly 0.2" gap between the lift tabs and F22 wth > the canard Trailing edge butted against the bottom of F28 and fuselage > sides (below the longeron doublers). Ouch! > > I read the archives, Marc's log, etc. but didn't see much about this > problem (makes me feel like the lone idiot). Someone added 10 plies > BID on one side of F22 to get square with the firewall. This > indicates that additional layups on front of F22 is probably do-able > and suggested in plans, but 0.2" seems like a lot. > > Checked everthing I could think of to find source of the trouble and > possible fix ideas. Here's what I have: > > Using a Rube Goldburg setup with two squares, my canard measures > roughly 6.15" from the rear of the lift tabs to the trailing edge. > > Measuring the templates and adding in the shearweb and > hard-point layups results in about 6.125"; can't complain about what I > got. Fairly close to the templates. > > Chapter 6, Page 1, Figure 3 shows 5.9" measured from the rear of > F22 to the rear of F28; but doesn't indicate wheather that is taken at > the center of the bulkheads or at the fuselage. There is a > significant diference caused by reinforcements on F22 at the sides). > I may not have a problem if this measurement is intended at the > fuselage side. However, this figure is not referenced in the text for > F28 installation. > > Chapter 6, Page 2, Figure 9 shows 5.9" measured from the front of > F22 to the front of F28; This figure is also refered to in the text > at the point where F28 is instaled. This is what I used and exactly > what I have now. > > Drawing M-11 (supposedly a full size drawing, which is also used to > plot the shape of the nose etc) shows the front of F22 to the front of > F28 to be 6.1". It also shows the distance from the front of F22 to > the canard TE to about be 5.95" > > Drawing M-11 also shows the distance from the rear of F22 to the > rear of F28 to be 5.75". I measured 5.4" near the fuselage on mine > (this would be 'with' the reinforcement layups. > > The above obviously points to some errors in the plans, but doesn't > help with a fix unless I missed something.... > > I'd like some suggestions as to a fix, particularly from those who > have passed this point and even done the canard cover etc. Here's > some possibles; if there is one I missed, please add to the list: > > 1. Scrap the canard and reduce the cord to that on M-11. Screws up > the aerodynamics to be sure. > > 2. Add BID layers or plywood and BID on the front of F22 to take > up the gap. Changes the lever arm of the forces on F22. Also moves > the distance from the wing to canard forward about 0.2" which may > result in too much lift from canard (easier to deep stall). > > 3. Cut out F28 and reinstal/replace it 0.2" further back. > Do-able, but the outside of the fuselage has already been shaped and > glassed, including top longeron shaping/glassing. > > 4. Cut 0.2" notchs in the fuselage sides (vertical area of the > canard cut out) to accomodate the TE. Do-able, but creates a > significant weak spot in the fuselage below the top longerons. Could > add a couple plies of BID around this inside and out, but not sure of > the resulting strength and makes finishing the outside more > interesting. > > 5. Trim 0.2" off the canard TE between the fuselage sides only. > In my case, this leaves about 0.3" or maybe a bit less glass-glass > contact area on the TE. Do-able, but may weaken the torsional load > capability of the canard too much and unknown amount. > > Thanks for any help or suggestions. > > Larry Schuler MK-IV #500 Disheartend temporarily in Wisconsin > lschuler@cellular.uscc.com > > From: lschuler@cellular.uscc.com Date: Thu, 02 Apr 98 11:25:09 -0600 Subject: COZY: Chapter 12 - Canard mounting Two items. 1. While waiting for the canard tip micro fill to cure for a couple days I jumped ahead to chapter 12 to do some initial fitting of the canard to the fuselage. Believe I mentioned the anticipated problem of excess space between the lift tabs and F22 in a previous detailed note. Didn't go away; it got worse. After leveling everything it turns out that the gap is not 0.25" as originally guesstimated; it's 0.35". I'm still at odds with cutting part of the TE off, but may need to do so. If I cut back in the fuselage (which will also take out the bottom part of F28 below the doubler), that would place the TE behind F28 making the alignment tab layups rather strange. A new F28 may be my 'best' solution. Anyone who is further along see any problems down the road if I move F28 back about 0.29"? (See below for the other 0.06") The easy solution is to just cut the TE 0.1", the fuselage 0.1", add a 0.1" shim to F22, and let the rest be taken up by the F22 plies added in chapter 13. That would certainly be do-able; but seems a bit sloppy (yes I'm anal). 2. I also flipped ahead to chapter 13 to review the nose mounting since final drilling of F22 is postponed till then. Think I discovered another issue. I'd like to know if this is real or imagined from those who have gone before. If it's real, I can take advantage of it to solve problem #1. Chapter 12, step 2 has us mount the canard such that the lift tabs are tight against F22 (using BID shims as needed - no indication of how many layers of BID for shim is too many) and the lift tab CN-2 bushing flanges end up tight against the longeron doublers at F28. In chapter 13 (page 7, paragraphs 2 & 3 to be exact) we apply 5 additional plies to the face of F22 (2 corner plies and 3 reinforcing plies). I believe this will create a 1/16" gap between the alignment tab bushings and the Doublers. Is this true? Did I miss something? If it is true, it seems a bit sloppy after all the effort to get things tight in chapter 12? Just FYI, I will be using the tube and bolt method for the alignment tabs as described in the archives. Therefore a gap at the alignment tabs concerns me because it will set up unnecessary stress in the tabs when I tighten the bolts and could cause a change in canard AOA. The change would be very small and in the 'safe' direction, so that's not a major concern. The unnecessary stress is. Even if I use the straight pins called for, a gap will allow for unnecessary vibration and unwanted eventual weakening in the lift tabs. Not good. Larry Schuler Plans #500 almost done with ch-11 lschuler@cellular.uscc.com Date: Thu, 02 Apr 1998 18:44:18 -0500 From: "Jeff S. Russell http://www.AeroCad.com" Subject: Re: COZY: Chapter 12 - Canard mounting lschuler@cellular.uscc.com wrote: > After leveling everything it turns out that the gap is not 0.25" as > originally guesstimated; it's 0.35". > > I'm still at odds with cutting part of the TE off, but may need to do > so. If I cut back in the fuselage (which will also take out the > bottom part of F28 below the doubler), that would place the TE behind > F28 making the alignment tab layups rather strange. A new F28 may be > my 'best' solution. Anyone who is further along see any problems down > the road if I move F28 back about 0.29"? That is the best thing to move. F28 should be called F28.30 Just cut the bulkhead out and re-glass in the new location and your problems will go away after this. I have done this on 2 airplanes :-) -- Jeff From: cdenk@ix.netcom.com Date: Mon, 26 Oct 1998 06:06:38 -0600 (CST) Subject: Re: COZY: Ch 12 - canard locating pin On 10/25/98 21:25:49 you wrote: > >I was looking through the archives and saw a brief discussion on >alternatives to the canard locating pin which would make the canard >easier to remove, namely inserting a rod through the longeron and >using a bolt / nut to hold the locating tab. I'm wondering if the >locating tab may not need the ability to slide slightly on the >locating pin due to flexiing etc., in which case rigidly bolting it >in place would be a problem. Comments? > > > >Jim Hocut >jhocut@mindspring.com > > > > > I don't know why the plans locating pins at the upper longeron would be objectional, I have had my Canard off and on numerous times, and those pins are transparent, they just drop in. If you are having problems, possibly there are some geometery problems. For the Canard Tab bolts, I have nut plates, the Bolt heads forward, and use an offset ratcheting box wrench to tighten and loosen. From: SWrightFLY@aol.com Date: Mon, 26 Oct 1998 07:46:54 EST Subject: Re: COZY: Ch 12 - canard locating pin In a message dated 10/25/98 8:27:59 PM Central Standard Time, jhocut@mindspring.com writes: << I'm wondering if the locating tab may not need the ability to slide slightly on the locating pin due to flexiing etc., in which case rigidly bolting >> It is my understanding that bolting where the locating tabs are is not a problem. I have bolts in that location as my canard must be lifted straight up to clear the rudder petal assembly mounted of F-22 in my Stagger EZ. Steve Wright Wright Aircraft Works LLC