stall characteristic

[anitelite]

I have always liked the Sweet, Ugly, or whatever "Stik" type airplanes with the fat fuses, fully symmetrical wing, and weird tail. They have excellent ground handling and are very user friendly particularly for intermediate type flying. I've built at least 6 of these at varying times over the last twenty or so years. So, I decided to build one again and electrify it. Same exact ".40" size except the usual lightening techniques so when ready to fly, all up weight is around 4-1/4 to 4-1/2 lbs which is just right.

Here's the rub. Plane flies great ( AXI 2280/12 on ten cells, with 11x7 prop) except for the stall. On the other "slimer" types, the airplane would mush straighaway with high descent rate or break out straightaway. Not on this one. It ALWAYS breaks left. Wing is straight, rudder and elevator correctly aligned. Weight and balance correct. IS this a torque issue? Everything is zero-zero. Do I need to add a little positive to the wing and 2-4 degrees right and down?

Thanks for reading and comments. Jim

[Ollie]

It is easy enough to determine the answer for your self by this flight test:

Climb to an altitude that will allow some glide time and stall recovery from a deep stall with altitude to spare. Stop the motor and establish a glide. Slowly pull back on the stick adding up only as the glide slows. Let the stall develop. If it breaks the same way all the time, you have an undetected assemetry in the airframe such as an aileron misalignment, one wing heavier than the other or a airfoil shape difference between the left and right wing. There are an uncounted number of ways that a plane can lack symmetry. If it mushes straight ahead or breaks to either side unpredictably, then you have a thrust line adjustment to make that will correct the way it stalls under power.

You should trim the ailerons and rudder for a straight glide and a straight power off stall. Then, without changing the aileron and rudder trim, adjust the thrust line for a symmetrical stall under power.

The assymmetry under power could be due to the spiral slipstream over the wing giving one wing a different angle of attack than the other or it could be motor torque or P-effect or other things I haven't thought of. The vertical thrust adjustment should be such that there is little change in altitude during level flight except at low throttle.