flyhi

My Feedback: (28)

I tipped stalled my bipe on takeoff, not enough airspeed. Anyway, my questions is, can you tip stall a bipe on landing if you're heading in, nose down. I assume if you loose too much airspeed and stall, that's one thing, but will it stip stall and snap roll, or is the only time you do that is on climbing? thanks. I know to keep my speed up on landing a bipe, but get nervous anyway.

Rodney

I have several bipes, both sized Lazy Aces, Phaeton 90, Phaeton 40, 1/4 scale Moth and I can fly them all in at almost walking speed. All have very tame stalls (you really have to work to put them into a spin) and fly like trainers. Wing incidence settings are critical though, especially on the upper wing. All mine work out to about -1.5 degrees on upper wing with 0 on elevator and lower wing and about 3 to 5 degrees downthrust and 1.5 degrees right thrust. Minor tuning on these parameters can turn a tiger into a real ***** cat.

flyhi

My Feedback: (28)

thanks, got this bipe used, it's an old andrews aeromaster and have never checked incident or thrust lines. will do so soon, thanks.

jaka

Hi!
The most important thing to check is if the wing has any washout built into it or not (or worse.... has wash-in built in, then it will stall very easily).
Engine trust and incident angle is not that vital compared to having wash-out!

Regards!
Jan K
Sweden

MinnFlyer

My Feedback: (4)

Something else to consider...

Maybe your plane DIDN'T tip stall on takeoff. A bipe has a shorter wing than a monoplane, and therefore is more susceptible to torque. Was it the left wing that dropped on takeoff? If it was, there's a good chance that you left the ground before sufficient flying speed was achieved, and the torque of the engine was to strong to be overcome by the short wingspan.

flyhi

My Feedback: (28)

It snapped to the right upon takeoff, I was about 3-4 feet high. no real damage to bipe. (it even bounced and landed back on the wheels, and, as we all know, no matter what, if it ends up on the wheels it's not a crash I'm new at bipes, been flying 5 years but my first bipe. I'm pretty sure it was due to lack of airspeed. I've flown it since once and just got plenty of airspeed and it went okay.

ec121k

It's very important like the previous response to have the forward, in this case the upper wing at a higher incidence angle. then, it will be the first to stall and of course lose lift. With the loss of part of the wing lift and it being forward, the nose will drop and the stall will be less violent.

If it's a "Stagger Wing", and the lower wing is forward, then you want the lower wing to stall first for the same reason. If you set up that Aeromaster correctly, it should be just fine. Also, make sure you have the CG as specified on the plans.

Good Luck,
Tony

Rodney

ec211k, While that may work for you, in the 12 or more bipes I have successfully flown and still fly, ALL required about 1.5 degrees less angle of attack in the upper wing than in lower wing. I have had some that I tried to fly with equal angles of attack and one with positive in the upper wing. All became very unstable and tended to porpoise in level flight. On my big Phaeton 90 just a change from -1.5 to -1 caused it to become very erratic at some attitudes. I quickly restored it to -1.5 degrees negative.

Ed_Moorman

My Feedback: (1)

The classic set-up for an RC biplane was originated by, as I recall, Harold DeBolt many years ago. It is lower wing at 0, upper wing at plus 1-1.5 deg, and the stab at plus 2-3 deg. That is, the stab is at the highest incidence, then the top wing, then the lower wing.

Having the top wing (normal stagger, not reverse) at a positive angle causes it to stall first. Now visualize the plane with the top wing removed. You have a long nosed, low wing plane that is nose heavy making stall recovery easy.

If the lower wing is more positive and stalls first, the result is similar to a short nose, high wing plane that is tail heavy, making it more snappy.

Varying the amount of incidence can change this a great deal.

Many years ago, the Balsa USA bipes were all set up at 0-0-0 which resulted in a poor flying airplane that tended to climb under high power like a trainer. This has been corrected over the years. I occassionally get to test fly an older Phaeton that someone has found and can attest to their goofy flying if not set up correctly.

The Andrews Aeromaster could be built in several wing configurations, including short and long wings and straight and swept wings. I have always felt the configuration with both wings long and swept was the best flying one. I had one with shorter wings and it was snappy. Jerking the stick around would cause a snap.

Another point to consider is the extra drag biplanes have. The extra wing, struts and cabane cause a lot of drag compared to a monoplane. This can cause someone who is not familiar with bipes to lift off at too slow a speed or get too slow on final with resulting snaps. Once you get in ground effect they land very slowly, however, if you try to fly one like a trainer and flare at 20 feet and let it float down, you can be in trouble.

Bipes are also short coupled and short winged which causes them to be more easily affected by torque and other twisting forces.

Finally, you may have a warp in one wing causing a premature snap.