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#1
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Reprofiling LS6 wings
Hi all,
Given that down the track I will need to refinish my wings, I am curious about the process. I understand that LS/DG will not provide profile information to allow accurate reprofiling of the wings. Is it standard practice to just reinstate the profile that the wing had prior to refinish? Has anyone taken a profile from another aircraft to use, for example using a later LS6-c to reprofile an LS6-b? What about using an LS8 profile on an LS6, since they are supposed to be the same forward section? Thanks, Ben |
#2
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Reprofiling LS6 wings
On Jun 19, 3:28*pm, Ben C wrote:
Is it standard practice to just reinstate the profile that the wing had prior to refinish? That's pretty much what you do. Make sure the wing profile is round in front, pointy in back, and the waviness is below .004", and it will probably be fine. ...Has anyone taken a profile from another aircraft to use, for example using a later LS6-c to reprofile an LS6-b? They're the same profile. Or at least the LS6-c left is the same as the LS6-b left, and likewise for the corresponding right wings. I've done template checks on several LS6 and a couple of LS8 to validate it. What about using an LS8 profile on an LS6, since they are supposed to be the same forward section? As you note, they're also pretty much the same, within the qualifications noted above. My advice: Don't bother trying to do a full profile job. The LS6 and LS8 go like stink, generally fly very straight, and handle very well. There is just about nothing a full profile job will do to change that. It will defnitely add a bunch of weight and expend hundreds of hours and thousands of dollars. About the only things that would make much of a difference are the leading edge profile back to about 15% chord, and getting the waviness down to under .004". And my bet is that both of those are probably already in pretty good shape. Thanks, Bob K. http://www.hpaircraft.com/hp-24 |
#3
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Reprofiling LS6 wings
On Jun 19, 9:04*pm, Bob Kuykendall wrote:
On Jun 19, 3:28*pm, Ben C wrote: Is it standard practice to just reinstate the profile that the wing had prior to refinish? That's pretty much what you do. Make sure the wing profile is round in front, pointy in back, and the waviness is below .004", and it will probably be fine. ...Has anyone taken a profile from another aircraft to use, for example using a later LS6-c to reprofile an LS6-b? They're the same profile. Or at least the LS6-c left is the same as the LS6-b left, and likewise for the corresponding right wings. I've done template checks on several LS6 and a couple of LS8 to validate it. What about using an LS8 profile on an LS6, since they are supposed to be the same forward section? As you note, they're also pretty much the same, within the qualifications noted above. My advice: Don't bother trying to do a full profile job. The LS6 and LS8 go like stink, generally fly very straight, and handle very well. There is just about nothing a full profile job will do to change that. It will defnitely add a bunch of weight and expend hundreds of hours and thousands of dollars. About the only things that would make much of a difference are the leading edge profile back to about 15% chord, and getting the waviness down to under .004". And my bet is that both of those are probably already in pretty good shape. Thanks, Bob K.http://www.hpaircraft.com/hp-24 Hi Bob, I am a newbie in the sport and wondering how much wing surface deformity would one expect to see in this era glass ships. The deformity is caused by shrinking/ settling of fiberglass through time or there is a different mechanism? The more recent ships with carbon fiber wings suffer just a much? BTW, I enjoy following your work. Thanks Khanh |
#4
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Reprofiling LS6 wings
On Jun 19, 3:28*pm, Ben C wrote:
Hi all, Given that down the track I will need to refinish my wings, I am curious about the process. I understand that LS/DG will not provide profile information to allow accurate reprofiling of the wings. Is it standard practice to just reinstate the profile that the wing had prior to refinish? Has anyone taken a profile from another aircraft to use, for example using a later LS6-c to reprofile an LS6-b? What about using an LS8 profile on an LS6, since they are supposed to be the same forward section? Thanks, Ben Only the first 4" are critical and I would make 'quickie' templates before stripping the wing. Set wing leading edge up on saw-horses and mark span locations every 18" then make rough cardboard templates starting at the root. Place wax-paper over L/E and goop up your rough template with Bondo and lower them onto each indicated location. After the Bondo dries remove and sand the edges to leave only the center 1/4" template. Be sure to mark each template 1 through 16, or so. Then start the fun part, with a Porter-Cable, variable speed electric orbital sander using 60 grit, 6" sticky back disks..................remove all the gelcoat down to, but not including the fiberglass structure. Check back after the 2 weeks this may take and I'll give you the next step in you all Winter project. Cheers, JJ |
#5
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Reprofiling LS6 wings
Before I make myself out to be too much of an idiot with a mostly-
likely-obvious question... is there a quick quide on the process of re- profiling? My search in Google just now was fruitless, so I'm doing something wrong. I'm not planning on doing it, but I'm curious about the process. Thanks! - John |
#6
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Reprofiling LS6 wings
On 06/21/2011 10:11 AM, jsbrake wrote:
Before I make myself out to be too much of an idiot with a mostly- likely-obvious question... is there a quick quide on the process of re- profiling? My search in Google just now was fruitless, so I'm doing something wrong. I'm not planning on doing it, but I'm curious about the process. Thanks! - John Hi John, this is probably the best article to give you an idea of the work involved. http://www.archive.jimphoenix.com/ar...UP%20wing.html Luke Szczepaniak |
#7
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Reprofiling LS6 wings
On Jun 21, 10:11*am, jsbrake wrote:
Before I make myself out to be too much of an idiot with a mostly- likely-obvious question... is there a quick quide on the process of re- profiling? *My search in Google just now was fruitless, so I'm doing something wrong. *I'm not planning on doing it, but I'm curious about the process. Thanks! - John Yep. Reprofiling only. Identify and fill low areas- usually due to shrink over time. Identify and remove high areas- rare, but it does happen. Where are they? Ah that is the question. Throw in refinishing and that is a whole different question. The first time you do this you will do well not to make the glider worse. Many do. Few do it the second time. UH |
#8
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Reprofiling LS6 wings
On Jun 21, 11:37*am, wrote:
On Jun 21, 10:11*am, jsbrake wrote: Before I make myself out to be too much of an idiot with a mostly- likely-obvious question... is there a quick quide on the process of re- profiling? *My search in Google just now was fruitless, so I'm doing something wrong. *I'm not planning on doing it, but I'm curious about the process. Thanks! - John Yep. Reprofiling only. Identify and fill low areas- usually due to shrink over time. Identify and remove high areas- rare, but it does happen. Where are they? Ah that is the question. Throw in refinishing and that is a whole different question. The first time you do this you will do well not to make the glider worse. Many do. Few do it the second time. UH That's the thing -- not to make it worse. Is it worth it to try though? My plane seems to fly about 10-12% worse than the Johnson measured polar. The gelcoat is in pretty good shape overall after 33 years though; it looks like a reprofiling is basically a refinish project, which I'm not planning on doing anytime soon. -- Matt |
#9
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Reprofiling LS6 wings
Okay, I think need to be an idiot and ask the questions (I beg your
indulgence)... I understand the part about getting the correct profile templates and shaping the wing to the correct profile. However, doesn't that mean that the wing will be thicker than profile once the gelcoat is sprayed on? Or are the templates made deliberately thinner to account for this added thickness? But then how would one know how thick to lay on the gelcoat? It seems to me that "re-finish" and "re-profile" are being used nearly interchangeably, i.e. in both cases, the gelcoat is completely removed. Can it be that the gelcoat can be only partially sanded off, filled in somehow (more gel?) to meet profile, then bond in another layer of gelcoat? I've seen a wing repaired: new foam core, glass layers, bondo then gelcoat, so I know small patches can be done this way (I didn't get to see the gelcoat being applied). Thanks! -John (and if these are _really_ stupid questions, just call me Hugo) (no offense intended to anyone named Hugo) |
#10
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Reprofiling LS6 wings
On Jun 21, 11:54*am, jsbrake wrote:
Okay, I think need to be an idiot and ask the questions (I beg your indulgence)... I understand the part about getting the correct profile templates and shaping the wing to the correct profile. *However, doesn't that mean that the wing will be thicker than profile once the gelcoat is sprayed on? *Or are the templates made deliberately thinner to account for this added thickness? *But then how would one know how thick to lay on the gelcoat? It seems to me that "re-finish" and "re-profile" are being used nearly interchangeably, i.e. in both cases, the gelcoat is completely removed. Can it be that the gelcoat can be only partially sanded off, filled in somehow (more gel?) to meet profile, then bond in another layer of gelcoat? *I've seen a wing repaired: new foam core, glass layers, bondo then gelcoat, so I know small patches can be done this way (I didn't get to see the gelcoat being applied). Thanks! -John (and if these are _really_ stupid questions, just call me Hugo) (no offense intended to anyone named Hugo) The best step-by-step I've ever found was on Jimphoenix.com. He stripped, reprofiled, and refinished a set of Nimbus wings. Unfortunately, I don't think it's still available, as he has moved to Washington and is now more into boats. It might not hurt to email him to see if he could send you the 'article'. Cheers |
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