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need to build a trainer wing

Old 06-24-2013, 04:08 PM
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k-vette
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Default need to build a trainer wing

I picked up a new hobbico superstar .40 trainer - but its missing the wing. I know its a 60" span and can guess the chord based on the fuse mounting.

Ill build in some dihedral, but will I need some washout in the wingtips?
If I want slower flight, could I increase the chord length without any ill effects? There's plenty of room to mess with cg. I haven't bought a brushless motor or esc yet.
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Old 06-25-2013, 01:33 AM
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Originally Posted by k-vette View Post
I picked up a new hobbico superstar .40 trainer - but its missing the wing. I know its a 60" span and can guess the chord based on the fuse mounting.

Ill build in some dihedral, but will I need some washout in the wingtips?
If I want slower flight, could I increase the chord length without any ill effects? There's plenty of room to mess with cg. I haven't bought a brushless motor or esc yet.
here you go, this will save you some time and building

http://www3.towerhobbies.com/cgi-bin...?&I=LXSM78&P=0

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Old 06-25-2013, 03:54 AM
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Thanks Chellie. I saw the wing on towerhobbies, but $75 seems way too steep for a wing. (Id rather buy a HK pnp jet or something for $69) I paid $30 for the plane and intend on selling the engine to cover that.

So I'm thinking of just spending a little and making a new wing, probably reinforced blucor. Since ill be making a wing, I might as well see if I can mod it a little bit along the way. My goal is to make it a nice easy flyer for training others.
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Old 06-25-2013, 04:22 AM
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You can look at the plans for other trainers to get an idea of the structural requirements.

Essentially 3/16 X 3/8 spruce spars top and bottom with shear webbing. 1/4 square stock on a corner leading edge. (plan ahead and the sheeting carries onto the LE stock and over the spars... makes things easier) A good dihedral brace, sheeting the "D tube" (everything forward of the spars) with 1/16 balsa. 1/4 X 3/8 balsa TE to the fixed poertion of thewing and appx 1.5 inch TE stock (tapers 1/4 to 1/16) Ribs of 1/16 balsa spaced about every 6 inches. Full sheet between the last 2 and between the center rib and 2 ribs out.

Little to no washout when doing ailerons. Maybe prop the TE of the wingtip up 1/4 inch.

Relatively low dihedral. 1 inch under each wingtip is plenty. You can go down to 1/4 inch under each tip.
Don't go to 0 because that looks like the wing is drooping. Not sure why but its an optical illusion that happens every time you go 0 dihedral with a trainer wing.

The center ribs need to be doubled with 1/4 inch balsa (both of them. on the side of them that won't be glued to the other wing panel) so there is plenty of "meat" to support the dowel for mounting the wing. (assuming you want to go to bolt-on.
1/16 ply plate on the top at the TE spreading 2 inches on each side of the fuselage and from TE 3 inches forward. This will either protect the TE from rubber bands cutting in or give support to the wing mounting bolts.

(that's all just off the top of my head... I probably left a few things out)

****************

Reinforced bluecore ... I don't think you want to play with a hot wire foam cutter.
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Old 06-25-2013, 11:54 AM
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Some Great info here on building a wing

http://www.airfieldmodels.com/inform..._construction/
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Old 06-27-2013, 02:38 AM
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Thanks for all the directions. I've never glassed anything and am considering this as a possible learning experience.

Anyone have thoughts on increasing the chord? I'd like some slow floaty flight if possible.
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Old 06-27-2013, 04:26 AM
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If you want floaty like a glider then increase span about 4 to 10 inches each side. Larger span will increase glider-like flying better than adding chord.

Make it removable plug-in wingtips (maybe 2 inches short of original span each side when the add-on is removed) so you can have the alternate flying characteristics for windier days.

When adding span you may need to add a bit to the fin/rudder area.

You could also add chord ... just make the ailerons have more chord and thus more area. Double the ailerons and you'll get a noticeable effect. Dial down the throws to keep the trainer roll rate... dial the throws up (and add rudder + elevator area) and you will have improved aerobatic capability.

It will always be a trainer... but you can play with changing stuff to see what the effects are.
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