From: lschuler@cellular.uscc.com Date: Mon, 26 Apr 1999 09:09:18 -0600 Subject: COZY: Ch 14 Ceneter Spar Ok gang, it's the idiot who can't read again. Chapter 14, Page 2, Step 3, 1st paragraph describes "layup 2". Later paragraphs/steps call out successive layups (3, 4, 5 etc). I can't seem to find layup #1 anywhere. Could someone point out the obvious to this illiterate builder? Larry Schuler MK-IV plans #500 Date: Mon, 26 Apr 1999 20:53:48 -0400 From: "Marc J. Zeitlin" Subject: Fwd: COZY: Ch 14 Center Spar Larry Schuler writes: >Ok gang, it's the idiot who can't read again. No, that's not the problem. The problem is that you're stuck in the Western linear thinking modality. You're laboring under the (exceedingly common) misconception that Layup #2 should come _after_ Layup #1. Think of these numbers merely as nomenclature, rather than as ordinates, and everything will become clear. >Chapter 14, Page 2, Step 3, 1st paragraph describes "layup 2". Later >paragraphs/steps call out successive layups (3, 4, 5 etc). I can't seem to >find layup #1 anywhere. Could someone point out the obvious to this >illiterate builder? Sure. Look at Step 4, same page, third line. Bingo. Layup #1 comes after Layup #2. Free your mind from the strictures of Western philosophy, and become more zen-like :-). -- Marc J. Zeitlin mailto:marcz@ultranet.com http://www.ultranet.com/~marcz/ From: lschuler@cellular.uscc.com Date: Tue, 27 Apr 1999 08:59:50 -0600 Subject: Re: Fwd: COZY: Ch 14 Center Spar Marc wrote: >The problem is that you're stuck in the Western linear thinking modality. >You're laboring under the (exceedingly common) misconception that Layup #2 >should come _after_ Layup #1. Ahhh, I see the light; and now am blinded by the facts. So much for my Logic-101 classes way back when... Higher education sure does come in handy. Shoulda taken Zen-101 instead. Isn't that where you just think (ie meditate) about something long enough, it all just kinda falls into place by itself... :-) Maharishi U (Fairfield, Iowa) here I come... (Always did want to learn how to levitate). :-) So much for levity {cute play on words; couldn't help myself}... In any case, the answer brings up another question: Should we be doing layup #1 first (since the number 1 comes before the number 2 in our western way of thinking); or do we complete step 3 first [which contains layup #2] and then step 4 [which contains layup #1] because 'step' numbers have some kind of priority over other numbers of the same base-10 system? Larry Date: Tue, 27 Apr 1999 23:08:00 -0400 From: "Marc J. Zeitlin" Subject: Fwd: Re: Fwd: COZY: Ch 14 Center Spar Larry Schuler writes: >... In any >case, the answer brings up another question: Should we be doing layup #1 >first (since the number 1 comes before the number 2 in our western way of >thinking); or do we complete step 3 first [which contains layup #2] and >then step 4 [which contains layup #1] because 'step' numbers have some kind >of priority over other numbers of the same base-10 system? Since it doesn't matter (one is not a prerequisite of the other), it doesn't matter. Feel free to use whatever order brings you enlightenment. -- Marc J. Zeitlin mailto:marcz@ultranet.com http://www.ultranet.com/~marcz/ From: lschuler@cellular.uscc.com Date: Tue, 04 May 1999 17:12:09 -0600 Subject: COZY: Ch-14 Spar Cross section Since I haven't recovered yet from my last foolish note about reading, figured I'd just jump right back in and continue the downward slide of my otherwise 'perfect' reputation. Ch 14, Pg 8, Section A-A shows jig dimensions of 5.12" and 8.41". Ch 14, Pg 6 shows jig to be 5.12" and 8.51" respectively. Ch 14, pg 7 CS1 and CS4 foam pieces show 8.51" width. May be misreading again, but either section A-A is right and the jig and foam layout is wrong or vis versa (or, I still can't read worth a flip :-)). Larry Schuler Date: Wed, 05 May 1999 20:01:14 -0400 From: "Marc J. Zeitlin" Subject: Fwd: COZY: Ch-14 Spar Cross section Larry Schuler writes: >Ch 14, Pg 8, Section A-A shows jig dimensions of 5.12" and 8.41". >Ch 14, Pg 6 shows jig to be 5.12" and 8.51" respectively. >Ch 14, pg 7 CS1 and CS4 foam pieces show 8.51" width. > >May be misreading again, but either section A-A is right and the jig and >foam layout is wrong or vis versa I used 8.51" and everything worked out OK. I think the answer is "vice versa". Never noticed that one - guess I figured that since I already had the jig built before I cut the foam, what did I care what the dimension was after it was already done? :-). -- Marc J. Zeitlin mailto:marcz@ultranet.com http://www.ultranet.com/~marcz/ From: "Schuler, Larry" Subject: COZY: Center Spar Cap Tapes Date: Fri, 6 Aug 1999 19:12:00 -0500 Hi all, I just finished laying up the top spar cap on the Center section Spar using 3" wide UNI tape supplied by Wicks. This was their part number 1600-3 which I received from them a few years ago. I had ordered more than needed for the Canard, but not enough for both sides of the main spar ($$$ issue at the time). Last summer I ordered more of the UNI tape (same part number) and just now opened the package to begin the bottom spar cap. Nice surprise. The tape is exactly 2-1/2" wide rather than the specified 3" and the cross threads are rather tight (very likely the cause of the reduced width). The tow count appears to be the same at 30, but I'll be darned if I'm going to try to count the fibers... I called Wicks and was categorically told that the tape is supposed to be 2-1/2" wide, that it always was, and that there is only one manufacturer of this stuff, and is therefore correct as it was received. I explained that an earlier shipment from them was the correct width of 3" as specified in the catalogs (for at least the last 4 years, in addition to current). I was told it must have been a misprint. They told me I could ship it back (at my expense of course), but offered no means of obtaining the correct tape from them. Nat, I think you have a problem here. This is extremely fishy to me and potentially very dangerous. It appears that Wicks got stuck with a bad mill run and is now trying to pawn it off on unsuspecting builders rather than getting the manufacturer to correct the boo-boo and replace it. You might want to 'ground' them as approved supplier (at least for the spar cap tape) until they fix this. Let me know if you need anything from my end to help you. I still have the entire 145 yard roll if you'd like a chunk of it. I find it difficult to believe that I could spread the 2-1/2" tape out to the required full 3" width during wet-out without making a mess of the structural integrity. It will be near impossible to keep the fibers straight, particularly going along the bend in the spar. Not good. Has anyone else run into this? If so, what was your solution? Any other suggestions? Larry Schuler, MK-IV Plans #500 Befuddled in Wisconsin From: "Russ Fisher" Subject: Re: COZY: Center Spar Cap Tapes Date: Fri, 6 Aug 1999 21:21:53 -0400 Hi Larry, >Last summer I ordered more of the UNI tape (same part number) and just now >opened the package to begin the bottom spar cap. Nice surprise. The tape >is exactly 2-1/2" wide rather than the specified 3" and the cross threads >are rather tight (very likely the cause of the reduced width). The tow >count appears to be the same at 30, but I'll be darned if I'm going to try >to count the fibers... Yesterday I received the order I placed with Wicks at Osh which included the tape for the canard. I just measured it, and on the spool it varies from 2-5/8" to 2-7/8". As you said, the cross threads are somewhat tight. If you lay it down flat like it will be in the spar, I seems to spread out to 3" without any gaps. I don't think you should have a problem. This topic was addressed quite thoroughly here within the last few months and if memory serves me correctly, I think the general concensus was that the tape was identical in mass, just woven tighter. Russ Fisher From: "Michael Antares" Subject: COZY: Spar tape Date: Fri, 6 Aug 1999 19:16:28 -0700 I just measured some left-over tape that I purchased from Wicks some time ago (I could furnish an invoice number if asked). It measures three inches as it should. However in one way it shouldn't really matter as once the cross threads are removed the objective becomes filling the trough up as much as possible. I remember squishing the fibers around to even out the trough at the top. There really aren't layers as such but just a mass of fibers, so it seems you would just use proportionately more tape to achieve the same final thickness. My two cents... Michael Antares Date: Sat, 07 Aug 1999 07:49:57 -0500 From: David Domeier Subject: Re: COZY: Center Spar Cap Tapes Larry, re "Not good. Has anyone else run into this? If so, what was your solution? Any other suggestions?" I think you will be OK....just make sure the spar trough is full when you finish the lay up. dd From: "John Slade" Subject: Re: COZY: Center Spar Cap Tapes Date: Sat, 7 Aug 1999 11:57:33 -0400 Larry, > I think you have a problem here. This is extremely fishy to me and >potentially very dangerous. I have the same tape from Wicks. I did the canard already and am about to do the center spar. I had no problems laying the tape down and filling the trough. It spreads when wet and the cross threads are removed. I watched the Rutan video where Burt did a spar cap without removing the cross threads. The tape was clearly wider in the video. I think they've changed the way they "package" the roving threads, but the net result is _exactly_ the same. >I find it difficult to believe that I could spread the 2-1/2" tape out to >the required full 3" width during wet-out without making a mess of the >structural integrity. It will be near impossible to keep the fibers >straight, particularly going along the bend in the spar. Not true. As you squeege out from the center and push down on the wetted threads they will remain straight as they fill the trough. my 2c - Its not a problem. Use the tape and move on. John Slade Cozy #757 http://kgarden.com/cozy From: "Darcy & Karen Reed" Subject: Re: COZY: Center Spar Cap Tapes Date: Sat, 7 Aug 1999 10:22:47 -1000 I found that the 2 1/2 UND tape spread and filled the canard spar cap troughs to the top as planned, also the main spar caps' top trough has the correct number plies after I was done. On the top spar of the canard I used two extra lay-ups to fill the trough (I cut it a little to deep) and the bottom spar cap was correct. I would have to go back and find the exact number of plies used in all. The main spar caps' top trough was dead on in the number of plies used and final contour. I will be filling the bottom trough next Saturday. My experience is that once the thread is removed the glass spreads out to the full width of the trough, including the lay-ups to fill the trough results in singular piece of "straight" und glass 3" wide and ? deep, after I rolled, stippled and squeegee out the air pockets. At first I wondered about the width, but that went away after the first couple of lay-ups. Have fun and just do it. :-) Darc >I find it difficult to believe that I could spread the 2-1/2" tape out to >the required full 3" width during wet-out without making a mess of the >structural integrity. It will be near impossible to keep the fibers >straight, particularly going along the bend in the spar. Not true. As you squeege out from the center and push down on the wetted threads they will remain straight as they fill the trough. my 2c - Its not a problem. Use the tape and move on. John Slade From: "Schuler, Larry" Subject: RE: COZY: Center Spar Cap Tapes Date: Mon, 9 Aug 1999 18:40:00 -0500 Nat wrote: >You now have answers from many builders saying the same thing I would have >said (I have been away). There is no problem. Just pull out the cross >threads and fill up the trough. So it's OK to squish the fibers around so that they may or may not maintain the horizontal or vertical straightness? If this is true, would standard uni work just as well and be as strong as normally straight tapes (lots of UNI plies I'm sure...)? Larry From: "Michael Antares" Subject: RE: COZY: Center Spar Cap Tapes Date: Tue, 10 Aug 1999 08:26:53 -0700 So it's OK to squish the fibers around so that they may or may not maintain the horizontal or vertical straightness? If this is true, would standard uni work just as well and be as strong as normally straight tapes (lots of UNI plies I'm sure...)? Larry I did a tremendous amount of "squishing" when I did my spar cap layups. The single fibers can be moved around very easily and it is possible to keep them straight while doing so. I actually dragged a steel straightedge along the top to even out the fibers when the trough was essentially full. That saved a lot of sanding later. I also (with heart in mouth) used a three inch wide belt sander to take off the bumps where the layers tapered. It was scary to contemplate what would happen if the belt sander slipped off the top of the spar cap but it actually was quite easy to keep it centered. The spar cap is NOT easy to sand by hand, believe me! From: jhocut@mindspring.com Date: Tue, 10 Aug 1999 12:05:08 -0400 Subject: RE: COZY: Center Spar Cap Tapes >If this is true, would standard uni work just as well and be as >strong as >normally straight tapes (lots of UNI plies I'm sure...)? A Vari-EZE builder told me that that's exactly what he had to do before the spar-cap tape was available. I'm sure it would be MUCH more work using UNI than it would be with the tape. I used one of the notched squeegees from West with some amount of success to keep the fibers straight. Jim Hocut From: SWrightFLY@aol.com Date: Tue, 10 Aug 1999 18:11:02 EDT Subject: Re: COZY: Center Spar Cap Tapes In a message dated 8/10/99 10:32:18 AM Central Daylight Time, mantares@pacbell.net writes: << If this is true, would standard uni work just as well and be as strong as normally straight tapes (lots of UNI plies I'm sure...)? >> I was of the understanding that the standard uni is E-glass. The straight tape is S-Glass. If this is correct you not have the same strength as uni. Steve Wright Aircraft Works LLC: Electric Nose-Lift for EZEs From: "Schuler, Larry" Subject: RE: COZY: Center Spar Cap Tapes Date: Tue, 10 Aug 1999 20:20:00 -0500 >I was of the understanding that the standard uni is E-glass. The straight >tape is S-Glass. If this is correct you not have the same strength as uni. >Steve I wonder if it's still better than squirly fibers though???? :-) Larry From: "John Slade" Subject: Re: COZY: 3" spar tape Date: Wed, 11 Aug 1999 00:01:51 -0400 Was said: > I can help out on the 2.5" width spar tape problem. While the "old" tape may be just fine, I want to point out that there IS NO PROBLEM with the 2.5 inch tape currently being supplied. I just finished my top spar cap and It worked just fine. Once the cross threads are removed it lays down nicely in 3 inches. The trough was easily filled with the plans recommended number of plys so we're definately getting the same amount of glass. In fact I had to skip a couple of plys to avoid overfilling. John Slade (finishing off Chap 14) http://kgarden.com/cozy Date: Tue, 10 Aug 1999 10:30:53 -0400 From: "Marc J. Zeitlin" Subject: COZY: Center Spar Cap Tapes Schuler, Larry writes; >I wonder if it's still better than squirly fibers though???? :-) I see the smiley, but the point is (and I agree with it, having laid up the main spar caps and the canard spar caps) that you don't GET squirrelly fibers - they straighten out with no problem with a squeegee and hair dryer. In fact, they straighten out so much that you've got to be careful not to get them piled up around the corner on the main spar. Gently pushing and squeegeeing WILL get you straight fibers and completely fill the trough. You'll be amazed how the tape spreads out. -- Marc J. Zeitlin mailto:marcz@ultranet.com http://www.ultranet.com/~marcz/ From: "Chris Byrne." Subject: COZY: Chap 14 Date: Tue, 28 Sep 1999 12:16:37 +1000 Builders Have just inspected the bottom spar cap on the center section spar and find that the area 12 inches either side of the sweep back point is a little low. (trough must have been a bit deep). Looks like it will need extra 3 to 4 extra layers. ---------------------- 24 in ------------ 14 in ------ 8 in --- 4 in Will this destoy the stress (bending) distribution of the spar? Should I just leave it and accept that its a bit low, after all, the required layers are all there. Thanks Chris Byrne Sydney From: MARC_ZEITLIN@HP-Andover-om1.om.hp.com Date: Tue, 28 Sep 1999 10:18:56 -0400 Subject: FW: COZY: Chap 14 Chris Byrne writes: > Have just inspected the bottom spar cap on the center section > spar and find that the area 12 inches either side of the sweep back point > is a little low. (trough must have been a bit deep). Looks like it will need > extra 3 to 4 extra layers. > Will this destroy the stress (bending) distribution of the spar? No, with caveats. You have locally increased the stress in the bottom spar cap. How much is not clear. > Should I just leave it and accept that its a bit low, after all, the > required layers are all there. Yes, depending upon the definition of "low". If you're talking about 1/16" or less (which it sounds like from your estimate of 3 to 4 layers) then I wouldn't sweat it. You've increased the stress by at most 4% (given an 6" to 8" high spar). If it's 1/8" or more, then you may have a problem. You will have increased the stress level in the glass in that area a substantial amount and without a fix, you might have to reduce the ultimate loading on your aircraft from 12 G's to 10 G's :-). (That's a joke, for those of you that aren't familiar with ":-)"'s ). -- Marc J. Zeitlin email: marcz@ultranet.com From: MARC_ZEITLIN@HP-Andover-om1.om.hp.com Date: Wed, 29 Sep 1999 08:00:18 -0400 Subject: COZY: Chap 14 I wrote: > > ....... You've increased the stress by at most 4% (given > > an 6" to 8" high spar). Someone asked: > How does making the spar cap too thick/strong increase the > stress? Maybe I wasn't clear enough - what I meant was that by decreasing the effective height of the spar (by having the cap be slightly below where it's supposed to be), the spar would be marginally weaker than it would otherwise have been. I was assuming with NO extra glass added, since this was the current condition of the spar. > .... And how in the world would any local increase in stress exceed the > extra strength afforded by the extra material? It's just not intuitive, and I > am weak in really sophisticated structural analysis..... Anytime you change the structure by either adding or removing material, you change the way that stress flows through the structure. It's possible (I'm not saying its GOING to happen, but it CAN) that adding some material to the spar cap could shift some stress to areas of the spar that weren't meant to have it, and this could cause them to break when they otherwise wouldn't have. When you add material, you're stiffening one area, and that could force another area to deflect instead, causing higher stresses. Hope this explains it better. Intuition is not always correct :-). -- Marc J. Zeitlin marcz@ultranet.com http://cozy.canard.com Non Impediti Ratione Cognitanis (C&C) Date: Wed, 29 Sep 1999 16:28:58 +0200 From: "Rego Burger" Subject: Re: COZY: Chap 14 There is a formula that goes somthing like this. The strength of a laminated core is a multiple of the 2 x the sq.rt of the distnace between them. Sorry for the lack of detail, I don't have the design file with me at work... Therefore do not make any big changes of core thickness. Régo Burger RSA Date: Fri, 01 Oct 1999 18:06:39 -0400 From: Blake Mantel Subject: Re: COZY: Chap 14 MARC_ZEITLIN@HP-Andover-om1.om.hp.com wrote: > I wrote: > > > > ....... You've increased the stress by at most 4% (given > > > an 6" to 8" high spar). > > Someone asked: > > How does making the spar cap too thick/strong increase the > > stress? > > Maybe I wasn't clear enough - what I meant was that by decreasing the effective > height of the spar (by having the cap be slightly below where it's supposed to > be), the spar would be marginally weaker than it would otherwise have been. I > was assuming with NO extra glass added, since this was the current condition of > the spar. SNIP! > Marc J. Zeitlin marcz@ultranet.com > Non Impediti Ratione Cognitanis (C&C) Now I know when one is new to a place he shouldn't make waves, but... Here is an idea that I had a long while ago. And I discussed it with a employee of Hexel who was building a Mk IV but due to the minimum order quantity, I never pursued it. Have a "custom" run of the spar cap uni tape made from S-glass strands rather than the standard E-glass. (Making the exact same tape with the different glass fibers) Since S-glass is stronger, tougher and stiffer than E glass, one could build the cap to the same physical dimensions and specs but have a stronger end product. IMHO the caps are already the stiffest structure in that area and the switch from the E to the S would be a benefit with out any noticeable side affects. (but any change can be dangerous) The drawback was that the smallest run possible was, I think, on the order of 5000 yards of finished tape. This was a bit much for my personal use, but if enough interest was shown it can be done. Just an idea, Blake MkIV Plans #0008 -- CUM CATAPULTAE PROSCRIPTAE ERUNT TUM SOLI PROSCRIPTI CATAPULTAS HABEBUNT. (When catapults are outlawed, only outlaws will have catapults....) Triumph Tiger Motorcycle page at: http://www.tiac.net/users/blakem/ My Email address is altered due to the prevalence of bulk Email senders. To send me mail remove the two *'s before the TIAC.NET. From: cdenk@ix.netcom.com Date: Sat, 2 Oct 1999 11:13:55 -0500 (CDT) Subject: Re: COZY: Chap 14 was said As part of normal flight, both hard landings and turblence, the structure including spars flex. Part of the design is that this flexing absorbs some of the load, reducing loads on fasteners and adjacent structure. I might be detrimental to change to a stiffer material. As an extreme example, take a weight suspended by 2 rubber bands, replace one with a string. A quick upward movement of the support most likely will break the string, and then overlading the rubberband either allowing movement beyond allowables or breaking entirely. From: "John Slade" Subject: Re: COZY: Chap 14 Date: Sat, 2 Oct 1999 13:31:19 -0400 >build the cap to the same physical dimensions and specs but have a stronger end product. Blake, I think someone else answered this, but I just wanted to reinforce (: the point. Nat told me that the spar is built to withstand 18g. Unless you're planning on pulling 19g I don't think you need it stronger. What you want is flexibility. The Cozy is VERY smooth in turbulence. I understand that this is partly because of the fact that you're suspended between the wings and the canard and partly because of the ability of the wings to absorb shock. John Date: Fri, 01 Oct 1999 09:22:08 -0400 From: "Marc J. Zeitlin" Subject: COZY: Chap 14 Blake Mantel writes; >Now I know when one is new to a place he shouldn't make waves, but... Oh, what the heck :-). >Since S-glass is stronger, tougher and stiffer than E glass, one could build >the cap to the same physical dimensions and specs but have a stronger end product. On the other hand, since the spars are already more than strong enough, why would one want to pay extra money to make them stronger still? It's good to improve things, but only if there's actually some payback to it. -- Marc J. Zeitlin mailto:marcz@ultranet.com http://www.ultranet.com/~marcz/ From: Fritzx2@aol.com Date: Mon, 22 Nov 1999 14:59:35 EST Subject: COZY: RE: Cozy: FEAR OF FLYING IN CIRCLES >I have been fearful of installing my >main spar for weeks now. I'm having >a hard time getting everything perfect. >I have actually found differences in all >3 of my levels. Any tips on this subject >would be greatly appreciated. >Hugh Farrior >Tampa You could approach this a couple of ways. 1) You could level the fuse with any level without regards to how level it is to the earth noting the orientation you placed the level on the fuse longerons to level it. Then when you level the center spar, simply place the same level on the spar the same way you placed it on the fuse side to side. After all, all your woried about is that the spar is matched to the fuse. For example, if the fuse leveled 1 degree lower on the port side because the level was off and then you leveled the spar with the level in the same orientation, then the spar would be 1 degree lower on the port side with a difference between the fuse and the spar of 0 degrees difference which is what you are really looking for in the first place. Imagine, then, that you could tilt both the fuse and the spar (which is now attached) 1 degree to absolute level and the plane is assembled correctly which would be the same as if you had a perfect level in the first place. This is cheap (can use any level) but takes a bit more care. 2)Check to see if any of the levels are correct relative to the earth's magnetic field by supporting the level at each end with small shims like a penny on top of a stack of paper until the level is centered and then swap the level end for end placing the level on the pennies at the same points (using the same points negates the fact that your level is not perfectly straight) and then see if the bubble is centered. If so, then you can use the level in any orientation without having to keep track. If not, adjust the bubble if possible, otherwise note the orientation. It's always a good idea to calibrate your level periodically just to make sure nothing has changed like when the level tipped over and smacked the concrete floor. Never happens right? :) 3) Or, you could use a water level which would always be the correct except in a hurricane while your house was spinning around the funnel cloud in which case forget about the plane. For small diameter tubing you have to keep track of the miniscus especially over a short level distance. Also, you would need a straight edge to compare the water level to and then you would eventially start to question how straight is that straight edge anyway which would put you right back where you started. Not really. More than one way to build it straight. John Fritz fritzx2@aol.com From: cdenk@ix.netcom.com Date: Mon, 22 Nov 1999 17:16:29 -0500 (EST) Subject: Re: COZY: RE: Cozy: FEAR OF FLYING IN CIRCLES I had the wings bolted to the spar, and leveled/aligned the wings for alignment when installing the center section spar. Note that the spar is flexible in torsion and when the strakes are built is your last chance to change the incidence of the wings. Date: Mon, 22 Nov 1999 10:39:42 -0500 Subject: Re: COZY: FEAR OF FLYING IN CIRCLES From: "Paul Comte" > I have been fearful of installing my main spar for weeks now. I'm having a > hard time getting everything perfect. I have actually found differences in > all 3 of my levels. Water levels can't lie. For leveling stuff I use plastic tubing and water. I bought T's and cut the hose into sections, try to keep an extra line in a jug of water, use a rope to raise/lower jug to get water to required height. Remember to empty tubing when finished as some product may absorb water and cloud. I like this method because you are measuring all points at once. Paul Comte Milwaukee, WI