RE: How many/long to make wing tubes.
On my 2m span pattern planes the wing tube extends about 30cm into the wing panels.<div>The position is slightly aft of the main spar position, Thin Carbon fiber tube, about 2cm thickness.</div><div>BTW they are foam wings with no internal spars, only sheeted.</div><div></div><div>My 1/4 scale Byron Cessna 195 uses alloy plates built into the wing between the a double thickness top and bottom spar made of bass wood, then sandwiched between the spar webbing.</div><div>They only extend say 20cm into the wing. I'd say the main spar ones are 1&1/4 x 1/8th inch in thickness. The rear 1/2 x 1/8th inch.</div><div></div><div>I wouldn't bother using anything other than carbon tubes. Super strong and weight absolutely nothing.</div><div>For your usage, 1inch at slightly forward of the main spar position and say 1/2inch slightly forward of the rear spar.</div><div>You'll need a light ply rib doubler at the critical points, make sure it extends under the spar.</div><div>It'll be the strongest part of the wing.</div><div></div><div>Troy Built Models stock tubes for the aerobatic scene.</div><div>Check them out and see what's available.</div>