bipe upper wing incidence
 

why can't you set the upper wing the same as the lower one.? I understand the concept of wanting the bottom wing to stall first but if you just stay ahead of stall speed why couldn't you set them equal. it seems like you would get more lift from the upper wing and maybe offset the drag penalty some.

Bipe Incidence
 

Actually, I'd think you'd want the top wing to stall first for a more gentle stall. Having the bottom wing stall first, unless you are flying a staggerwing, would make the plane snappy.

As for drag, that's a bipe's middle name. The cabane and the interplane struts add tons of drag and this isn't even counting the two wings. Some of the race bipes had a center pylon and streamlined struts, but you are still never going to approach a clean monoplane.

The usual bipe set-up is the top wing at 2-3 degrees positive, the bottom at zero and the stab at plus 1-2 degrees.

bipe upper wing incidence
 

From practical experience -Two Phaeton 90's, 7 aeromasters, 2 phaeton 40's,3 Lazy Aces Plus more--all have required about 1.5 degrees less angle of attack on the upper wing than on the lower one to fly nicely. Just a change of 1 degree can turn a doggy flier into a pleasure to fly. If at all possible, set yours up so you can make minor adjustments on the upper wing and try different settings; I can almost guarantee that there will be sweet spot that makes the plane come alive. Mine have also all required a fair amount of right and down thrust to maintain heading at all throttle settings.

bipe upper wing incidence
 

there is also postive on the stab 1.5-2 degress.

bipe upper wing incidence
 

Bipe wing incidence is always a problem.
"Conventional" wisdom uses the "gentler stall" setup.
.
It depends on what -you- want -your- airplane to do!
.
Putt around the sky "scale-like" Stearmann style... lots of incidence.
.
Scream around the sky "scale-like" Ultimate style..0-0-0!

bipe upper wing incidence
 

Tall Paul, would the same be applicable for a triplane??

Thanks

bipe upper wing incidence
 

.
My scalish Dr-1 has postive incidence in the stabiliizer. And it needs it!
The top wing is seriously above the vertical c.g., and creates a nose-up pitch.
The full-scale has the same problem. The pilot has to hold down elevator in level flight.
For scale, it's best to use what the full-scale has.
For a manuverer, keep it simple, and trim the elevator to suit.
And expect LOTS of drag! Dead stick landings will be fast!

bipe upper wing incidence
 

Tall Paul, thanks for the info :)

bipe upper wing incidence
 

Hi Pike Bishop.
Don't no details of what you have but there is a stock biplane arrangement the provides all around excellent performance.
These angles are in relation to the line of flight and assume acrobatic ability is desired.
Top wing one degree positive
Lower wing zero degrees
Horizontal tail three degrees positive
If stagger is oresent, balance on a line connecting upper and
lower centers of lift.
Force arrangement works!
Need more info contact me on E-Mail
Good luck!

Hal [email protected]