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Dihedral dilema

PostPosted: Wed Aug 14, 2013 2:03 am
by danos
Hi guys ive registered in hope I can get some help on a small project which is giving me a headache. My son brought a chuck glider 800mm wingspan I was really impressed with how well it glided and so well I converted it givng it a brushless motor etc n gave him a spare hi-tec tx rx I test flew it today but it wouldn't turn left and barely turned right. Ive just made the ailerons 25% bigger but something dawned on me as this glider has a Dihedral wing will ailerons work? Ive never flown or know anything about Dihedral wings n cant say ive seen ailerons on a Dihedral wing before. Also the ailerons weren't fully built into trailing edge they stuck out behind the wing slightly ive repositioned them as any normal plane has them. Could that of been why it wouldn't turn? ANy help or suggestions please :) Danos

Re: Dihedral dilema

PostPosted: Wed Aug 14, 2013 4:42 am
by cynr100
I've also not seen ailerons on a sub 1M with dihedral, would almost seem counterintuitive to the purpose of the dihedral. Can you revert to rudder and elevator?

Also check the throws to make sure they have the same degree of movement in all directions, you may have a trim setting that will only give you ,say, 30% throw in one direction. You may also have a mix in the Tx that would not suit the setup eg aileron with 10% rudder.

Another thing is to consider the thrust line of the motor, most are offset against torque roll by 2-3deg from the centre line. Having the thrust line perfect to the aircraft centre line can give turn/control issues.

Re: Dihedral dilema

PostPosted: Tue Aug 20, 2013 11:01 am
by iflylilplanes
Everybody has seen an aircraft with ailerons and dihedral, A380, 747 and the humble Pipers and Cessnas all have dihedral and ailerons, even the P51 and the Spitfire.

As in the previous post, 2 or 3 degrees right thrust and the same down thrust will held with straight and level flight. Ailerons generally have a differential (more up throw than down) this is because you have to counter the lift produced by the wing, and lastly, speed is a factor, the faster the aircraft is the less throw needed the slower the aircraft is more throw will help or larger ailerons will do with less throw. How fast dose you glider fly at half to full throttle?

Dihedral will counter the ailerons if there is to much, with an 800mm wing, 50mm at each tip would still work with ailerons to much more than that will start to counter the ailerons effectiveness, reduce the dihedral if necessary.

Just a little info from my experiences over the years.

Re: Dihedral dilema

PostPosted: Thu Aug 22, 2013 1:47 am
by cynr100
Thanks for the dihedral tips Dave, I have a surviving AXN wing set that needs something special done with it :lol: maybe the basis for a DIY slope soarer and the dihedral will help.