Triplane wings angle of attack
 

Hello Friends!: in first place, sorry for my poor English.
The question: a friend has a Fokker DR 1 Triplane, and he has a question: which is the Angle of Attack (dacalage) of every wing of the Triplane ?. I don’t remember the kit manufacturer, but it has 1,30 mts wingspan, and a saito.70 engine.
Thanks!!

RE: Triplane wings angle of attack
 

My Dr. 1 has 0,1,2 degrees of incidence starting with the bottom wing. The important thing is to have the top wing at a higher incidence than the others. This helps with the stall characteristics
Walt

RE: Triplane wings angle of attack
 

My Dr.1 has 0,1,2 doegrees of incidence from bottom to top. The most important thing is to have the top wing stall first,
Walt

RE: Triplane wings angle of attack
 

I'm not disagreeing with Walt, here. What I found actually supports what he is saying, and his plane flies, so it can't be wrong. This is an excerpt from an article on fullscale Dr-1 wing failures:

"The Dr-1 had aspect ratios of 6.8, 5.9 and 5.1 for the upper, middle, and lower planes, respectively. The wing section had a maximum lift coefficient of about 1.4. Making estimates of each of the triplane wings (working as independent surfaces) the planes would require 19.2, 20, and 21 degrees respectively to reach the maximum lift coefficient. When working at the same angle of attack (as in the aircraft alignment) The upper wing would produce a lift intensity about 9% greater than the lower wing............."

"The triplane system with its relatively smaller wing gaps and pronounced stagger would almost certainly have a greater value than this. Together with aspect ratio effects it is not unreasonable to suggest that the lift intensity of the upper wing of the Dr-1 approached twice that of the lower wing....."

What it says above is that the fullscale used the same incidence on all three wings, and differential lift from the larger top wing and the dynamics between the three wings meant the top wing would produce almost twice the lift of the bottom wing. My old Great Planes Dr-1 was set up with equal incidence, it flew fine. So.... you could go anywhere between zero incidence and Walt's setup and it would probably fly fine.

The article goes on to say that in the event of the loss of the top wing, it was thoretically possible for the plane to remain airborne on the lower two wings only. Wing area would be about 9.9 square meters, and the plane would have a stall speed of about 64 mph. I'd sure as heck hate having to land that fast in a plane famous for ground looping, but it sure beats the alternative, as happened to Lt.s Gontermann and Pastor, two German pilots who lost top wings on their Dr-1's a day apart. Both died.

You can find this entire article, and many more really interesting ones like it, on "The Aviation History On-line Museum"

RE: Triplane wings angle of attack
 

I build my biplanes with the lowest angle of incidence on the wing with ailerons as I want that wing to continue flying andcontrolling the airplane after the others have stalled. I also believe this is how they are supposed to be designed. If in doubt, I would make the top wing have the lowest angle of incidence, it would ad stability similar to dihedral when approaching stall speeds.

Oh, oh, I feel a disagreement coming on!

RE: Triplane wings angle of attack
 

Thanks a lot to both friends!!!
since the dr1 of my friend is not a thru scale model, and the wings maybe are a clark y airfoil, i think that the 0,1,2 could be best one, but i think that the 0,0,0 could work too. I comment this two replies to my friend. He will fly the triplane tomorrow. I'll coment what happened after his flyght, Thanks!!

RE: Triplane wings angle of attack
 

thanks to Mode one too! But I think that when the bottom wing stall first, It could advance in a sharp stall, do the CG will go forward to the top wings, I'm wrong?

RE: Triplane wings angle of attack
 

Gentlemen,

The upper wing should always be the last to stall. otherwise you lose aileron control and have some vicious stall characteristics.

RE: Triplane wings angle of attack
 

Tri planes are tough too much gong on:). The bottom wing should stall last and with the tripe the center wing could be the last to stall. If the wing that has the center of lift forward of the CG stalls last the plane goes tail heavy and will flop backwards. If the top wing wing stalls first the nose will drop and hopefully help gaining airspeed. It is tough luck it only has one set of ailerons on the top. The problem too is you want to see the onset of the stall so it would be nice that the wings stall in stages to keep the surprise down.

RE: Triplane wings angle of attack
 

I do agree the triplane is a very busy airplane. I think the best bet is to keep the speed on until just above the ground. However, I'm going to keep doing what I do and I recommend the rest of you keep doing what you do.

RE: Triplane wings angle of attack
 

Ok, yesterday the first flight was done (or almost done!) The setup of the triplane was: 2 º the upper, 1ª the middle, and 0 the lowest wing. But the wind took his power over the airplane: the triplane took speed, and the model went to left, and the right wing lift of and the model flips over. The 2 mm ply struts of the upper wing broke. (I think 2 mm ply is not enough to support a 1, 30 mts wing). I’ll report after the first success flight what happened.

RE: Triplane wings angle of attack
 

Kitfoxkid, The real Dr1 was head exactly straight into the wind for take offs and landings. Do yourself and the plane a favor fly when the wind is calm, especially for the first test flight!

RE: Triplane wings angle of attack
 

Thanks Mode One: but I don’t fly this little devil. If it where mine, you can be sure I’ll fly it in calm wind and with nobody around me in the first flight!! Thanks!

RE: Triplane wings angle of attack
 

It has been a number of years ago but I built the Proctor Fokker Triplane. The instructions made a very big deal of all three wings having exactly the same angle of incidence. The stall characteristics with varying angle of incidence were described as being very nasty. With all three wings the same mine flew very nicely.

RE: Triplane wings angle of attack
 

Can some one help me balance my  nitro triplane I want to know for sure if I should balance it on the top wing and the instructions don't say...Any help is greatly appreciated,,,Thanks in advance

RE: Triplane wings angle of attack
 

58mm back from the LE of the top wing
0 degree incidence on all 3 wings
A nce flying plane whenn you fix a few things
Read this thread before flying...
http://www.rcuniverse.com/forum/m_52...Proctor/tm.htm