Do wrinkles in wing covering affect flight performance?  
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Do wrinkles in wing covering affect flight performance? - 6/18/2008 7:19:43 PM   
Yishht87


 

Posts: 97
Joined: 4/5/2008
From: Geneva, SWITZERLAND
Status: offline 		Hello and I am a scratchbuilder. I am building an airplane right now and I am having my first experience with heat-shrink material. It is going pretty well, I am learning quickly, but it turns out to be I have 4 or 5 major areas with maybe 6-7 1 mm or 0.5 mm wrinkles in the wing covering. My question is, even with wrinkles would the airplane be able to lift off? Please don't post "repair the wrinkles" because I did as much as I could wihtout damaging the covering, just please say will the wing have pretty much teh same properties or not? Would the wrinkles affect the flight majorly ot the lift producedf? I know drag will be there, but since the wrinkles are at the trailing edge where lift is not present and air detaches from thew wing, will the plane fly pretty much the same as without wrinkles?

Thank you,
Yishht87.

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RE: Do wrinkles in wing covering affect flight perform... - 6/18/2008 7:48:14 PM   
Nathan King



Posts: 1468
Joined: 5/29/2007
From: Omaha, NE, USA
Status: offline 		Technically it will increase parasitic drag, or more specifically skin friction drag; however, I don't know a modeler that would feel the difference on our small models.


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RE: Do wrinkles in wing covering affect flight perform... - 6/18/2008 7:56:24 PM   
mboland



Posts: 221
Joined: 7/20/2007
From: BouldercombeQueensland, AUSTRALIA
Status: offline 		They WILL have an effect. The size, number and position will determine what sort of effect.

Some pics would help

Should not affect lift but may affect trim

An example, a club member changed his aerial location on a Bobcat by putting an aerial tube under the left wing about 10mm from the leading edge.
He could not work out why he suddenly had to hold HALF FULL RIGHT AILERON to maintain level flight.

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RE: Do wrinkles in wing covering affect flight perform... - 6/18/2008 8:21:33 PM   
Yishht87


 

Posts: 97
Joined: 4/5/2008
From: Geneva, SWITZERLAND
Status: offline 		wait let me get pictures please


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RE: Do wrinkles in wing covering affect flight performa... - 6/18/2008 8:34:35 PM   
Yishht87


 

Posts: 97
Joined: 4/5/2008
From: Geneva, SWITZERLAND
Status: offline 		here are pics

Attachments
Click to see fullsize image.
Click for fullsize 		Click to see fullsize image.
Click for fullsize


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Theory and dynamics is all bullsh*t. You only know it flies when you fly it...

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RE: Do wrinkles in wing covering affect flight perform... - 6/18/2008 9:29:20 PM   
Rodney



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Joined: 12/8/2001
From: FL
Status: offline 		It is highly unlikely to effect flight characteristics of your model. Now, on some wings, turbulators are deliberately installed near the leading edge of the wings and are claimed to improve performance so I guess it depends on the location and severity of the wrinkles.

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RE: Do wrinkles in wing covering affect flight perform... - 6/18/2008 9:33:40 PM   
mboland



Posts: 221
Joined: 7/20/2007
From: BouldercombeQueensland, AUSTRALIA
Status: offline 		It looks like it will fly OK, but I have to ask, have you heat shrunk it yet?

We have covered wings with worse wrinkles but the good ol' heat gun disguises quite a few sins.

Its just that the covering looks very slack. It is a built up wing I am assuming from the pics.

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RE: Do wrinkles in wing covering affect flight perform... - 6/18/2008 9:42:18 PM   
propbuster



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Joined: 10/6/2003
From: Black Mtn, NC, USA
Status: online 		Put a heat gun to it

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RE: Do wrinkles in wing covering affect flight perform... - 6/18/2008 9:44:46 PM   
Nathan King



Posts: 1468
Joined: 5/29/2007
From: Omaha, NE, USA
Status: offline 		Like I mentioned above, wrinkles of that size will not markedly effect performance. Have you tried a heat gun?


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RE: Do wrinkles in wing covering affect flight perform... - 6/18/2008 10:49:21 PM   
da Rock



Posts: 6711
Joined: 10/11/2005
From: western, NC, USA
Status: online 		Depends on what performance you're worried about.

Covering can add strength to structures. When the covering is loose, it certainly won't.

On wings, it actually helps resist wing flex. It won't give, and that can provide something.

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RE: Do wrinkles in wing covering affect flight perform... - 6/18/2008 10:57:55 PM   
da Rock



Posts: 6711
Joined: 10/11/2005
From: western, NC, USA
Status: online 		What is the covering?

Almost every covering can be applied such that the wrinkles will come out with the heating our irons can provide.

So why not iron them out? If raising the heat a little at a time doesn't do it, then it's worth the lesson to pull it off and apply fresh covering. Apply tightly enough that it's shrinking ability removes the remaining wrinkles.

Why would you want to leave wrinkles that might iron out. And if they won't, it's worth your effort to learn to cover without wrinkles. And to produce a model with a covering job that will actually add strength and not cause drag. The added strength isn't a lot, and the drag isn't huge. But you'd cut a better piece out of balsa if the 1st wasn't large enough wouldn't you?

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RE: Do wrinkles in wing covering affect flight perform... - 6/19/2008 12:07:50 AM   
crasherboy


 

Posts: 112
Joined: 10/21/2006
From: Bryant Pond, ME, USA
Status: offline 		If it were me,I ,would try to heat the wrinkles out. If I could not do that,I would recover. It will by no means help your flight characteristics to leave them in there.It would still fly I think,I also think it would act better if you took care of the wrinkles.

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RE: Do wrinkles in wing covering affect flight perform... - 6/19/2008 4:56:35 AM   
Yishht87


 

Posts: 97
Joined: 4/5/2008
From: Geneva, SWITZERLAND
Status: offline 		guys. what's a heat gun? I am afraid of touching the wrinkles because at the top i hadd to recover some parts because the covering just wrinkled and hasn't shrunk due to too much heat. I am using Solartex/film by the way- and I quite hate it actually wince it don't shrink much >(.

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Theory and dynamics is all bullsh*t. You only know it flies when you fly it...

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RE: Do wrinkles in wing covering affect flight perform... - 6/19/2008 6:06:05 AM   
mboland



Posts: 221
Joined: 7/20/2007
From: BouldercombeQueensland, AUSTRALIA
Status: offline 		Heat gun, or hot air gun, you can even use a hair dryer, but unless they have a dial in temp setting you have to be very careful.

For ages I just used a standard clothes iron.
adjust the heat settings very slowly, starting low, until you get a satisfactory shrink. If you have it too hot you will get a hole.
Try using some scrap on a piece of balsa or other material to get your temp right. Low setting should give you stick without much shrink, slightly higher gives the shrink you will require.

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RE: Do wrinkles in wing covering affect flight perform... - 6/19/2008 8:24:56 AM   
Yishht87


 

Posts: 97
Joined: 4/5/2008
From: Geneva, SWITZERLAND
Status: offline 		Wel I used a slightly higher setting this morning on my wing, tried the hair dryer- too cold for shrinking. Went back to ironing with higher temperature at about 150 degrees celcius. I successfully removed about 90 percent of the wrinkles that you see on the pictures of the yellow covered bottom part of the wing. The material is now very tight, althou