Building materials, covering

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blue cobra
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Re: Building materials, covering

Postby blue cobra » September 28th, 2009, 7:31 am

swimmerdude5 wrote: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!
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Re: Building materials, covering

Postby jander14indoor » September 28th, 2009, 11:55 am

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.

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Re: Building materials, covering

Postby swimmerdude5 » October 5th, 2009, 2:02 pm

thanks for the help i'm going to start bulding in a few days when the kit arrives 8-)
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Re: Building materials, covering

Postby mg » October 21st, 2009, 6:05 pm

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

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Re: Building materials, covering

Postby andrewwski » October 21st, 2009, 6:45 pm

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.
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Re: Building materials, covering

Postby Greg Doe » October 21st, 2009, 7:16 pm

mg
Boron is some nasty stuff. I won't go into detail, but trust me you don't need it for a Wright Stuff airplane. It requires some special handling, and won't make you any more competitive since the airplanes have to weigh 7 grams. If you were trying to build a 2 gram airplane to to the Science Olympiad rules, you might consider Boron filiment. It is going to be interesting to see if anyone comes up with a use for Carbon that actually makes a airplane more competitive. Conventional materials of wood (balsa, spruce, and bass) mylar, tissue, and grocery produce bags are going to be hard to beat. If and when you have mastered conventional materials, and can break two minutes in a standard gym (approximately 30 foot ceiling) you will know if Carbon will give you an advantage.
Good Luck
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Re: Building materials, covering

Postby smartkid222 » October 23rd, 2009, 2:33 pm

andrewwski wrote:. Generally you want to use a small bead or piece of teflon to separate the prop from the thrust bearing.


What the technical term for that? i keep forgeting.
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Re: Building materials, covering

Postby jander14indoor » October 23rd, 2009, 4:53 pm

smartkid222 wrote:
andrewwski wrote:. Generally you want to use a small bead or piece of teflon to separate the prop from the thrust bearing.


What the technical term for that? i keep forgeting.


Well, technically that teflon piece or bead is a thrust bearing and only a thrust bearing. Its only job is to reduce the friction from thrust forces.

The thing commonly called a pigtail thrust bearing has bearings in it, but would more accurately be called a prop hanger as it does some much more than reduce friction. The front face is a thrust bearing. The holes are axial bearings. The thing as a whole is a prop hanger.

Pictures:
Thrust bearing: https://www.a2zcorp.us/store/images/pro ... ashers.jpg or in brass: https://www.a2zcorp.us/store/images/pro ... ashers.jpg
Prop Hanger: http://www.indoorspecialties.com/index1.html

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Re: Building materials, covering

Postby kjhsscioly » October 23rd, 2009, 7:58 pm

Greg Doe wrote:mg
can break two minutes in a standard gym (approximately 30 foot ceiling) you will know if Carbon will give you an advantage.
Good Luck
Greg Doe
Smyrna,TN


I broke two minutes, but still have no idea what metal fiber has to do with this event

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Re: Building materials, covering

Postby Greg Doe » October 23rd, 2009, 8:44 pm

kjhsscioly,
Exactly. You made my point in one sentence. The only use that I have heard of for Boron filament
is for wing tip bows on ultra light indoor models, and reinforcement of weak areas. Unfortunately
Boron requires special handling to prevent puncture wounds to the model builder. Carbon on the other hand is much more user friendly. The question is "will someone find a use for carbon on a WS
airplane that will give them a competitive edge?"
Greg Doe
Smyrna,TN

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Re: Building materials, covering

Postby carneyf1d » October 23rd, 2009, 10:06 pm

Didn't Bill Gowen's record setting F1M have a Leading Edge composed soley of a carbon strip?

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Re: Building materials, covering

Postby carneyf1d » October 23rd, 2009, 10:11 pm

and by the way, boron will do no good in Scioly competitions unless they move weight down to under 2 grams. plus the stuff is a pain to cut and work with. Carbon plates are an interesting touch to this years rules, however i dont think its at all necessary to use if you want to win. With ultralight planes, carbon is super beneficial in order to strengthen the supports of a plane. However with 7 grams to work with, you can find some sturdy balsa instead. It'll save you a lot of time and money.

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Re: Building materials, covering

Postby blue cobra » October 24th, 2009, 10:00 am

How's Tru-Lite Poly Micro 2 covering? My WS mentor said, "you could get some of that if you want." So how much better is it than produce bags?

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Re: Building materials, covering

Postby jander14indoor » October 24th, 2009, 12:54 pm

Depends on how light a bag you find. They give the area weight on that web page for poly-micro.

From bags I've weighed, you'd save around .35 gm over the lighter bags.

If you use that .35 gm wisely for heavier structure your poly-micro plane will be slightly more durable and hold trim settings slightly better.

But that's a pretty small difference so if the two planes both weigh 7.0 gms at the end (and they SHOULD!), the winner will depend far more on you the flyer than on the covering.

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Re: Building materials, covering

Postby planemaker » January 8th, 2010, 5:12 pm

I have Mylar that came with the Freedom Flight Model kit is it a good covering
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