Some wobble is normal, but excess is inefficient.
Things to try or check.
Are your rotors balanced?
- For the 'free' rotor hold the motor stick horizontal, no rubber band. Does one blade always hang down, no matter where they start? If so, its heavy. Fix.
- For the fixed rotor, see if you can balance the horizontal motor stick with both blades level. If not, fix the side that always drops. Oh, take off the free rotor to do this.
Is the pitch even from one side to the other?
- Look along the rotor towards its axis, axis held vertical. The tip up should look symetrical. If not, fix.
Is the offset of the axis of the two rotors TOO great (not sure how much is too much, but try to keep it relatively small)? If so, redesign and rebuild.
Not sure motorstick or rotor hanger bending will make it wobble, but it does introduce other problems. So, evaluate, is it bending? Where, stick or hanger?
Bending motor stick. If you are under weight, brace it by laminating a small piece of hard stiff balsa on the side away from the motor stick. If you are at weight, you'll have to make another. How much weight did you budget for the stick? I'm guessing around 1.5 to 1.8 gm is about right. Cut a bunch of sticks, sort all around the weight target, select the stiffest. Shortening the stick will make it stiffer AND lighter. Note, you may NOT want hard, stiff balsa for the motor stick. To hit weight it has to be too skinny. Instead, select a very large cross section but low density piece of balsa. See the Wright Stuff historical threads for more discussion on why this works.
Bending prop hanger. Are you using the plastic Ikara hanger? I've always found those too flimsy. Try an aluminum one like those Harlan sells. You can also bend your own.
Note, someone thought the plastic Ikara hanger would not be legal, didn't think the rules were written that way, but read them yourselves when available in a week or so.
Hope that helps,