Rudder causes pitching

[rorywquin]

I am building a new AcroWot (a very popular sports aerobatic plane in the UK) to replace my last one that was wrecked in a mid-air collision!

The only real criticism of this aircraft is that when you apply rudder - either direction - it dives.... I corrected this on my previous AW by mixing in a bit of up elevator with rudder in my transmitter.

On one of the UK forums and recently in a magazive, they recommend that installing the horozontol stab 1" lower than the plan shows almost eliminates the problem.

Is there any valid sceince behind this theory before I go and "modify" my new aircraft?

[Bill Mixon]

Yes the Horizontal stab placement can make a difference in this situation. It's hard to say whether or not moving it down will help that much though. From everything i've read moving it down would in theory make the problem worse.
I searched for Acrowot and found some pictures of one. It looks to have a semisemetrical wing with dihedral.
I guess one thing that could be done is to make a new vertical stab with the hinge line slanted rearward. This should produce some amount of up effect when deflected.
But if you know that the stab lowering worked you might want to try that first.

Bill

[rorywquin]

Bill

Thanks for your input. I read in a magazine thet lowering the stab helps but wanted better infor - I will probably stick to the designed position and use mixing to correct it !