From: "John Slade" Subject: COZY: Chap 21 - how to fix my strakes? Date: Mon, 24 Jan 2000 08:42:48 -0500 Good morning, fellow builders. I have good news and I have bad news. The good news is that my strakes are both the same. The bad news is that they're both about 3/4 inch out. Bottom skins are glassed and in line with the wings. Top skins are floxed in place, but the upper surface is not yet glassed. While trying to fair the foam for the top skins I find that, as best as I can describe it, my strakes are too long. A straight edge placed anywhere along the forward 6 inches of the strakes meets the wing about 3/4 inch outboard of the joint line. If I could magically shorten the R33 and R57 ribs by about 1/2 inch, everything would line up. Before I start attacking the strakes with a chainsaw, my question is: What's the best way to fix this? 1. Let the strake fairing extend past the cut line on the wing. Sounds ugly? 2. Cut the top skin away back to the flat part, "adjust" the ribs, then put the top skin back? 3. Saw the suckers off the spar, remove 1/2 inch and stick them back on. Option 2 seems the best to me, but I'm not sure how to get a good seal at the join. Any input would be appreciated. Regards, John Slade, Cozy MKIV #757, progress: http://kgarden.com/cozy West Palm Beach, FL From: "ZEITLIN,MARC (A-Andover,ex1)" Subject: COZY: Chap 21 - how to fix my strakes? Date: Mon, 24 Jan 2000 08:54:55 -0700 John Slade wrote; > ..... my strakes > are too long. A straight edge placed anywhere along the forward 6 inches of > the strakes meets the wing about 3/4 inch outboard of the joint line. If I > could magically shorten the R33 and R57 ribs by about 1/2 inch, everything > would line up. I'd be interested to know how you think you got the bottom strakes lined up well, but the tops are out of whack? > Option 2 seems the best to me, but I'm not sure how to get a > good seal at the join. Here's what I did when patching a section of the strake that I had to remove to fix a leak (and this was with the top skin on, so your situation will be easier): Cut a 2" wide "swath" of foam off of the inner skin where you'll have to cut through the skin to remove the front of the strake. Sand the OUTER surface of the inner skin on both pieces. After adjusting the size and position of the strake skins, flox the skin back on. Use a 2 BID tape to glass over the inner skin at the joint, where you removed the foam. Micro 3/8" foam back into the 2" wide joint area, and then sand flush with the surrounding foam. Voila' - ready for the external glassing. -- Marc J. Zeitlin marc_zeitlin@alum.mit.edu http://cozy.canard.com Non Impediti Ratione Cogitantonis (C&C) Date: Mon, 24 Jan 2000 09:00:34 +0000 From: Eric Westland Subject: Re: COZY: Chap 21 - how to fix my strakes? John Slade wrote: I've posted an image at http://kgarden.com/cozy/strakes.jpg On it I've drawn > black lines showing where a straight edge meets the wing and marked FS60. > > Looks like the front of BDE bulkhead is 1 inch forward at FS 59, and yes - > that causes the whole nicely curved, beautifully smooth upper strake skin to > be too far forward. If I "fair" it into the wing the strake will have > noticible a jiggle at bulkead OD. If I carry it straight to the wing I'll > "overlap" the join. Guess I should have thought about this before closing > the strakes. Me too. I have one side this way to some degree, it mostly "misses" at the leading edge. I just faired it in like you mentioned. While it really bothered me, no one else even noticed and I eventually stopped noticing it myself. . If it has any effect on the flying qualities, they are probably offset by some other minor boo-boo I made on the other side. Bottom line, it flies straight and no one can see it when I'm at 10,000 feet :-). Eric Westland From: "John Slade" Subject: Re: COZY: Chap 21 - how to fix my strakes? Date: Mon, 24 Jan 2000 10:54:59 -0500 Régo Said >any small error is no big deal as long as you have duplicated it on both left and right... >symmetry is the issue. Even 1/2" is not so bad really.... if it is on the leading edges as I >think it is then make adjustments there to mate with the wings. Sketches would help >more than words in this case to avoid a miss interpretation. ROB said Are you saying that the cord line at the root of the strake is too long?? If so, by an inch or so?? I've posted an image at http://kgarden.com/cozy/strakes.jpg On it I've drawn black lines showing where a straight edge meets the wing and marked FS60. Looks like the front of BDE bulkhead is 1 inch forward at FS 59, and yes - that causes the whole nicely curved, beautifully smooth upper strake skin to be too far forward. If I "fair" it into the wing the strake will have noticible a jiggle at bulkead OD. If I carry it straight to the wing I'll "overlap" the join. Guess I should have thought about this before closing the strakes. The only thing I can see to do is cut the top skin back, cut out BDE and TTE change the shape of the ribs and flox it all back together. Oh - one other thing. While trying to spline sand the top skin into the wing I reached glass for 6 inches at the outboard end. John Slade From: "John Slade" Subject: Re: COZY: Chap 21 - how to fix my strakes? Date: Mon, 24 Jan 2000 11:54:44 -0500 Marc said: >I'd be interested to know how you think you got the bottom strakes lined up >well, but the tops are out of whack? That's easy. I was kidding myself that at least I got something right. The bottoms are out too. Jack said: >This is a common problem. It is usually caused by the Wing not the strake. >A common error is to forget to cut the wing at the right angle. If the foam >wing Blocks are glassed as cut at BL 67.5 they would cause this problem. Check >chapter 19 Page 10. In any case is fairly easy to cut the wing at an angle to fit the >strakes. I had to do it. No, I did cut the wings to a right angle. But trimming the wing to match the strakes sounds a lot easier than opening up the tanks top and bottom, both sides. I'd end up with a join line at about 95 degrees to the spar, but I don't see that this would matter. I just made a urathane fairing to fit the gap. It curves a bit, but doesnt look too bad - or am I kidding myself again? John Slade From: "ZEITLIN,MARC (A-Andover,ex1)" Subject: COZY: Chap 21 - how to fix my strakes? Date: Mon, 24 Jan 2000 12:10:28 -0500 John; > That's easy. I was kidding myself that at least I got something right. > The bottoms are out too. Aha. > I just made a urathane fairing to fit the gap. It curves a bit, but doesnt > look too bad - or am I kidding myself again? As long as you haven't increased the area of the strakes too much, it's only an aesthetic issue. If it looks good to you, go with it. -- Marc J. Zeitlin marc_zeitlin@alum.mit.edu http://cozy.canard.com Non Impediti Ratione Cogitantonis (C&C) Date: Mon, 24 Jan 2000 11:34:16 -0600 From: David Domeier Subject: Re: COZY: Chap 21 - how to fix my strakes? Eric, I sent a private message to John saying essentially the same thing ....bottom line is "a little fill here and a little fill there" cures some of the frustration and once the machine is flying it is gradually forgotten and unless you refer to your notes and have public confessions in the town squrare on "sins of a builder", no one will notice. The strake/wing joint is very difficult to get perfect in anything less than half a life time...press on, John, your airplane will be just fine. dd From: "Russ Fisher" Subject: Re: COZY: Chapter 21 Fuel Vents Date: Wed, 26 Jan 2000 12:39:38 -0500 From: Michael Link >One idea that I did not incorporate but may consider doing is to run a braided >copper strand of not too great a diameter through the vent tubes. At the strake >end I plan to have the braid attached to a piece of Al ( similar to the fuel >cap) and laying in the bottom of the tank. The other end of the braid would >exit the manifold (sealed,of course) and attach to my main engine/aircraft >ground on the firewall. The theory is that the line guy can then clip his ground >wire on the exhaust pipe ( as so many want to do anyway) and actually accomplish >something. On new construction you could also attach the braid to some copper >screen embedded in the inner strake skin in the vicinity of the fuel cap. >Just an idea. Any comments from the group? Michael, Yes - absolutely! Your idea is logical, however it will not work. Refer to Sport Aviation, Dec. 1998, page 55. There is an excellent CAFE report on fuel handling. In it they state, and proved by experimentation, that fuel is non-conductive. The static charge is generated at the filler neck by the friction of the movement of the fuel through the nozzle into the tank, just like rubbing your shoes on a carpet in low humidity. On a metal airplane, this charge is dissipated by the frame to the grounding clamp. On our plastic planes, the frame is non-conductive, just like the fuel. The charge, therefore, has nowhere to go - it stays right at the filler neck. It will not travel through the fuel to your copper ground lead on the bottom of the tank. I suppose you could connect the wire to your filler neck, but there are other proven methods to accomplish this. If you don't have access to the article I referred to, send me a fax number or address and I will be glad to send it to you. Russ Fisher From: gmellen@us.ibm.com Date: Fri, 7 Apr 2000 11:21:48 -0400 Subject: COZY: Strake Vents I am getting ready to bond the top skins of the strakes. I have added two vents per tank. One per plans and one on the forward face of the spar. They both exit the strake at the aft/fuselage corner of the strake What is the best way to insure a good seal where these lines exit the top skin? George Mellen IBM Global Services Bank One Delivery Team gmellen@us.ibm.com 614-244-4438 From: "Ed Richards" Subject: COZY: Re: Chapter 21 Strake Windows Date: Fri, 7 Apr 2000 22:36:55 -0400 > Bill Kastenholz wrote: So what is the word on strake windows?< Bill, I installed strake windows in my Cozy, but I'm not sure I'd do it that way again. They are next to useless from the front seat because you can't really get a good look. Maybe the back seat would benefit, I'm not sure as I haven't had any passengers in there yet. My opinion is that it wasn't worth the extra time. What I really wish I had added were fuel gauges. I don't know what others do to see the sight ports but when I'm flying there is no way to see the left tank. I'm going to try and install a small mirror perhaps this will work. Ed Richards Cozy IV N826ER From: "Ryan A" Subject: Re: COZY: Re: Chapter 21 Strake Windows Date: Fri, 7 Apr 2000 20:54:31 -0700 Bill, Being a passenger in a Long EZ for about a year now, I do like the strake windows. On some long trips (including OSH'99) there are times where being able to look straight down was nice. I did say nice because I do not plan on being a passenger in my Cozy. I am not sure about the view in the back of a Cozy but with the Long the Pilot can see a ton more expecially where the strake blocks the view of the passenger. This is where they come in handy. I guess it would also depend on how often you plan on carrying passengers. You can always add them later. Just my 2c Ryan Amendala Cozy MKIV #855 ----- Original Message ----- From: Ed Richards To: Cozy Builders List Sent: Friday, April 07, 2000 7:36 PM Subject: COZY: Re: Chapter 21 Strake Windows > > Bill Kastenholz wrote: > So what is the word on strake windows?< > > > Bill, > I installed strake windows in my Cozy, but I'm not sure I'd do it that way > again. They are next to useless from the front seat because you can't > really get a good look. Maybe the back seat would benefit, I'm not sure as > I haven't had any passengers in there yet. My opinion is that it wasn't > worth the extra time. > > What I really wish I had added were fuel gauges. I don't know what others > do to see the sight ports but when I'm flying there is no way to see the > left tank. I'm going to try and install a small mirror perhaps this will > work. > > Ed Richards > Cozy IV N826ER > > From: gmellen@us.ibm.com Date: Fri, 2 Jun 2000 21:18:33 -0600 Subject: COZY: Strake Bulkheads I am getting ready to close up my strakes. My question is how to treat the exposed foam were there are cut outs through the bulkheads? My assumption would be to leave it bare foam since the plans do not say. George Mellen Cozy #607 From: "Brian & Susan DeFord" Subject: COZY: Re: Strake Bulkheads Date: Fri, 2 Jun 2000 22:09:05 -0700 > > I am getting ready to close up my strakes. > My question is how to treat the exposed foam were there are cut outs > through the bulkheads? > My assumption would be to leave it bare foam since the plans do not say. > George, That's correct - no treatment is necessary since this is a closed cell foam and the foam is not degraded by fuel. Brian DeFord Cozy MK-IV N309BD http://www.deford.com/cozy From: "John Slade" Subject: Re: COZY: Strake Bulkheads Date: Sat, 3 Jun 2000 10:13:33 -0400 Was said: >> My assumption would be to leave it bare foam >That's correct - no treatment is necessary since this is a closed cell foam >and the foam is not degraded by fuel. Somehow I just couldn't bring myself to leave it bare. I did flox corners in the cut outs before installing the ribs, thinking this would be hard to do later. George - at this stage, be sure you have a good line from the front of the strake to the wing joint. I didn't and it cost me a lot of aggravation. Have fun! Regards, John Slade, Cozy MKIV #757, progress: http://kgarden.com/cozy West Palm Beach, FL From: "Brian & Susan DeFord" Subject: Re: COZY: Strake Bulkheads Date: Sat, 3 Jun 2000 08:25:21 -0700 > Was said: > >> My assumption would be to leave it bare foam > > >That's correct - no treatment is necessary since this is a closed cell foam > >and the foam is not degraded by fuel. > > Somehow I just couldn't bring myself to leave it bare. I did flox corners in > the cut outs before installing the ribs, thinking this would be hard to do > later. > Perfectly acceptable - but not necessary. It takes time to do it and will add some incremental weight but probably well within the tolerance of the amount needed to build the strakes. Brian DeFord Cozy MK-IV N309BD http://www.deford.com/cozy