Building materials, covering

Greg Doe
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Re: Building materials, covering

Postby Greg Doe » January 9th, 2010, 12:10 am

Planemaker
The mylar in your kit is good stuff. It is difficult to handle, and it tears very easily. Follow the
instructions in the kit, and take your time. If you have a lot of trouble, consider covering your
first airplane with tissue (preferably Japanese tissue). Good model airplane tissue can be
bought mail order, or occassionally at some well stocked hobby shops.
I usually have my students cover their first airplane with tissue because it's a little easier to
work with.
Greg Doe
Smyrna, TN

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Re: Building materials, covering

Postby jander14indoor » January 10th, 2010, 10:57 am

Mylar is good (very light, a little hard to use) for SO.

Tissue works, but is on the heavy side, though it is possible to build 7.0 gm planes with light tissue (which can be hard to find). It also tends to shrink and expand with changes in humidity, which can cause warping problems at unexpected times.

A good alternative between Mylar and tissue is grocery shopping bags, believe it or not. You do have to look for the lightest, flimsiest ones you can find (ask the shopper of the family who's bags tear the easiest) to save weight, but you can come in about half the weight of light tissue, and their available everywhere for free, just takes time to find the lightest. I've had fairly consistent success with bags from Home Depot and one of the pet stores (Petsmart?). In covers like mylar but is easier to handle, and doesn't shrink like tissue. A good compromise.

Jeff Anderson
Livonia, MI

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Re: Building materials, covering

Postby 14mjensen3 » January 11th, 2010, 2:28 pm

Though a paper covering can be light, i found that a plastic covering* can be just as useful and light. Plus it makes the wing struckture more study during flight and building.


*a plastic covering can be procured at most hobby stores. This plastic is the same as they use for model planes. It is a little more expencive than paper but it can be applied more sturdely.

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Re: Building materials, covering

Postby planemaker » January 11th, 2010, 5:35 pm

jander14indoor:

I had heard that home depot bags work well so i brought a few home thx
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Re: Building materials, covering

Postby jander14indoor » January 12th, 2010, 9:01 am

14mjensen3 wrote:Though a paper covering can be light, i found that a plastic covering* can be just as useful and light. Plus it makes the wing struckture more study during flight and building.


*a plastic covering can be procured at most hobby stores. This plastic is the same as they use for model planes. It is a little more expencive than paper but it can be applied more sturdely.


Careful, there are plastic coverings, and plastic coverings. The commonly available plastic coverings in most hobby stores for RC planes is WAY heavier than tissue, and WAY, WAY heavier than the indoor mylar. Even the lighter RC coverings (Coverlite or Microlite) for the newer indoor RC planes is heavier than good tissue.

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Re: Building materials, covering

Postby blue cobra » February 17th, 2010, 8:27 am

Is Tru-Lite Poly Micro film:

https://www.a2zcorp.us/store/ProductDetail.asp?Cguid={891FACE1-D730-4B62-80E3-27912F8D2DD5}&ProductID=1548

the same thing as mylar? It's 0.9 microns thick.
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Re: Building materials, covering

Postby eta150 » February 17th, 2010, 10:14 am

Yes, and no. Mylar is a brand name used to describe a type of poly films. That isn't called mylar for that reason. However, is is made from the same stuff.
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Re: Building materials, covering

Postby blue cobra » February 17th, 2010, 3:50 pm

So Mylar is like Kleenex and Tru-Lite Poly Micro film is like other brands of tissue; the same thing by a different name? If I'm understanding you, thanks.
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Re: Building materials, covering

Postby eta150 » February 18th, 2010, 5:58 pm

That's my understanding, yes.
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Re: Building materials, covering

Postby eta150 » February 22nd, 2010, 1:50 pm

Alright, serious problem. I am flying the leading edge kit, and my wing is WAY too close to 40cm for comfort. The good people at Solon allowed me to fly, because after manual measurement, they saw it sitting right at the 40cm mark. However, I do not see the people at regionals being so kind. I have till next monday, and their are several reasons why I do not want to rebuilt my wing, like time constraints and the fact that my current plane is pushing 3 mins. and won Solon. Is there any way to reduce the wingspan by about a millimeter? Also, these measurement are including the tip plates, which rest on the sides of the wing.
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Re: Building materials, covering

Postby jander14indoor » February 22nd, 2010, 2:55 pm

The Freedom Flight design doesn't have much dihedral does it. Sometimes increasing dihedral a little can get the span under limit if you are close, but not with a flat, or nearly flat wing. Too much dihedral change needed to affect span.

Here's how I'd attempt it.
First, make sure you are fresh and relaxed, this is going to be finicky, don't wait till the contest or you'll be VERY sorry. Make sure you have a good place to work.
OK, ready to start.
Carefully cut off the tip plate. If real solid, consider doing this when you cut off the outer rib later (below). If you used balsa cement, consider dissolving it off. I wouldn't use debonder if you glue with CA.
Make an extra rib, make sure it fits snugly between the spars at one outer rib. Coat the top with your favorite covering stickum and glue it just inside the outermost rib. Leave just enough space between the two ribs to slip an knife between to cut off the outer rib. I'd use balsa cement on ends of the rib to glue to spar to prevent gluing the new rib to the old. Let it dry VERY well, overnight if possible.
Carefully cut off that outer rib with a real sharp knife.
Re-attach the tip plate.

This may all fail, be prepared mentally to make a new wing. Heck, you may want to make a new wing FIRST as a security blanket. Probably easier.

And don't worry! If you are winning contests like Solon at 2:45 plus, you can do it again if you build a new wing carefully.

Jeff Anderson
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Re: Building materials, covering

Postby eta150 » February 22nd, 2010, 3:00 pm

Just so you know, regionals are on Monday, and the wing is only over by the tiniest bit, if at all. It is also not a freedom flight design, but a leading edge. Thanks, though, because I'm sure that will work just fine if necessary.
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Re: Building materials, covering

Postby eta150 » February 22nd, 2010, 3:01 pm

If it is just the tiniest it over, though, do you think a simple sanding and recovering of the tip plate could work?
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Re: Building materials, covering

Postby leetx » February 22nd, 2010, 3:13 pm

I would consider sanding the tip plate.

First, be sure you know exactly how much you are over the limit, and where along the wing span. Perhaps the sanding has only be a little bit at only a few spots.

second, are you comfortable sanding the tip plate while it's on the wing? If so, I would do as you suggested: uncover the tip plate, sand at the right places, and recover. You must also be comfortable afterwards to recover the tip plate while it's attached to the wing.

Third, you can also sand the tip plate after you detach it. When I attach a tip plate, I attach it only in 3 spots to reduce the glue weight. In my case, I expect that I can easily remove the tip plate. If this is the case, then I would sand the tip plate after removing it from the wing but keep it covered. I would sand the inside, along the right spots, to reduct the width.

As jander said, if you proceed, be mentally ready. It's definitely do-able.

Good luck.

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Re: Building materials, covering

Postby Greg Doe » February 22nd, 2010, 8:24 pm

Eta150
My kids had the exact same problem, wing too close to 40 cm. They fixed it exactly as
Jeff Anderson described, but let me add a few specific suggestions. Work on the right wing,
unless you have a very good reason to shorten the left wing. Cut a new tip rib and, and make
it a snug fit. Apply glue stick glue to the top surface of the rib. Install the new rib as close to
the old tip rib as you can, leaving the slightest gap. Glue the new rib in place. Remove the tip
plate. My students only glue the tip plates in 3 places so that they are easier to remove. Cut
off the origional tip rib, and re-glue the tip plate. My girl team did it in about 30 minutes.
At one of our events last year the judges considered the tip plates as part of the wing span.
It's probably best to build your wing with that in mind, unless you know the judges won''t include
the tip plates in there measurement. Good Luck.
Greg Doe
Smyrna, TN


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