Building materials, covering

[andrewwski]

Mylar - no, you'd melt it. Japanese tissue, yes, without steam.

[Greg Doe]

Don't iron the mylar. It will melt. Surprisingly crumpling the mylar greately reduces the static cling.
Gently crush the mylar into a ball. Then spread it out on a smooth surface. Transfer it to a stretcher frame. Make the stretcher frame large enough to cover the largest surface you will be covering on your airplane in one piece; that will probably be one wing panel.(half of the wing). Time spent on making a good stretcher frame will be well spent. This year that will be 20 CM, but make it at least a half inch longer for convience. Use chap stick on the edges of the stretcher frame.The chap stick will allow you to pull any large rinkles out of the mylar before it is transfered to the airplane surfaces. Use glue stick, or 3M 77 (or similar) contact cement on the wings, sparingly. Working with mylar is tedious, and requires a lot of patience! It would be advisable to start with a rudder or elevator so that if you make a mess, you will have less time in building a replacement part.
Again, working with the mylar will try your patience. For this reason I have my students cover their first airplane with tissue. Good luck.
Greg Doe
Smyrna, TN

[jander14indoor]

I actually cover the wing in one piece. Depends on your source of mylar. If a piece from a kit, it might not allow that, but if from a roll you can generally orient it so you can use one piece.

And don't forget grocery store bags. The light, flimsy, annoying ones. If you look around you can find them much lighter than tissue, and only a little heavier overall than indoor mylar films. Last year my 7 gm demo plane was covered with Home Depot bags as they were the lightest I found at the time. This year it may be another store, tends to vary a lot by batch. Its free (except your time) can have pretty logos or silly savings, has all the advantages of mylar (no shrinking) and is easier to use.

Jeff Anderson
Livonia, MI

[swimmerdude5]

Where can i get a good stretcher frame. Thanks for the tips but in the wing there are other pieces of wood between do i just put mylar on top of it all or between each and every one of the? Also how can i stick the grocery bag onto the wood?

[jander14indoor]

You make it, not exactly a commonly used item.

See the following article on the National SO web page for Wright Stuff:
http://soinc.org/sites/default/files/up ... icfilm.pdf

Note, while I like using grocery bags for cost, and, frankly, outrageousness, they vary greatly in weight. I've seen from area density ranging from 5 gm/m2 of condenser to over the 20 gm/m2 of Saran Wrap (and note that Saran Wrap is the heaviest listed, nasty stuff). Make sure you are using the light stuff or stick with tissue in the 8-11 gm/m2 range.

See also this article from the Indoor Duration website with some pictures:
http://www.indoorduration.com/INAVCovering.htm

Finally, for SO planes, I seldom bother with a frame. I just spread the covering smoothly on clean poster board and drop the glue sprayed frame on it.

Jeff Anderson
Livonia, MI

[blue cobra]

Where can i get a good stretcher frame. Thanks for the tips but in the wing there are other pieces of wood between do i just put mylar on top of it all or between each and every one of the? Also how can i stick the grocery bag onto the wood?

For glueing the grocery bag to the wood, you spray it with contact cement, 3M 77 is the best, but other kinds work or I heard you can also use a glue stick. The contact cement is going to spray everywhere, so put the wing in front of cardboard (a pizza box works great), spray the top, then put it on wax paper and cover it (unless you are going to drop it on top of the covering like jander14indoor said).
If you want to use a stretcher frame, I'm fairly certain it's just a square frame of wood. Make it. Attach the covering to it with some slack to accommodate the curve of the ribs. I personally don't like the stretcher frame, and I just get someone to hold two corners as I hold the other two, and we we pull it taught and set it on the wing, then I rub my finger over the wood to make sure it is attached everywhere.
When you talk about other peices of wood between the wing do you mean the curved ribs and some supports? Yes, you want one peice of covering for the whole wing, or two if you make it a certain way:

There are two common ways for making the wing. For simplicity I'll assume you have only 1 dihedral point (making a V shape). Black line is your wing, red line is the covering you should use. You can build your wing flat like this:
____________________
________________ EDIT: Imagine the covering is centered over the wing, with some slack on either side.
put two ribs close together in the middle, partially break the wing between them to get your dihedral, and glue the break.

Or, some people make two wing halves separately:
___________ ___________
________ and ________
then glue them together.

Note: I didn't include the hight of the ribs in my drawings.

I hope I answered your questions!

[jander14indoor]

Forgot the rib part. Hard core indoor types that build sub 1 gm planes don't put glue on the ribs, but only the outline to save weight. For SO, don't sweat it too much, as long as you minimize over all glue use when covering by only spraying lightly, it won't be a big deal. Doesn't seem to affect performance much either way.

Jeff Anderson
Livonia, MI

[swimmerdude5]

thanks for the help i'm going to start bulding in a few days when the kit arrives

[mg]

Hi
I came across Pigtail Thrust Bearings in Ray Harlan's website. What are they used for?

Also, is Borron fiber the same as carbon fiber?

MG

[andrewwski]

Thrust bearings are used to attach the prop to the motor stick. The hook and wire go through the bearing, which is attached to the motor stick, and the wire then goes through the prop in front of the bearing. Generally you want to use a small bead or piece of teflon to separate the prop from the thrust bearing.

Boron fiber and carbon fiber aren't the same. Boron fiber comes from boron, carbon fiber comes from carbon. You may be able to use them for similar applications, but I don't believe the rules allow boron fiber.