HI Bob,

A lot of stunt planes were designed with an airfoil vertical stab and rudder.  And in the old days, quite a bit of rudder offset was used. 

Most "new" designs are 0-0 offset, or VERY minimal.  The pervalent theory is to eliminate any crabbing of the plane and have it flying tangent to the circle.  I always cheat with a touch of engine offset, just to insure no "inset".

My son's (he's 30) new Satana (Randy Smith 40 piped plane) had wraped a *little* inset to it by the time it was finished and test flown.  The plane still flew amazingly well at the only contest he's flown it at.  It has since been correct to "0".

Don't know if that answers your queston! 

Thanks Bill ,

I can see why too much offset of engine and rudder would cause some serious "yawing".
The main thing I'm conerned about is not having enough "pull on the lines and losing the ship during test flights .
I grasp the theory , of having the aircraft wanting to fly in a straight line ( away from the circle , or arc ) , as long as the lines are adjusted properly and no "inset" being predominant .
Again , thanks a bunch
Rob Killick

I hear ya, Rob!
Always a major ear of mine, no matter how many planes I've built.  It's the age old test flight fears!   
My current PAMPA plane, my Geo Juno, has an adjustable rudder.  It has "maybe an 1/th" offset, and I could probably lose that.  But I have reduced it quite a bit from what I set it at for the first flight.
I tend to get the plane flying a *little* on the fast side for that first flight.  Speed will keep it out there in level flight.  As I start manuevers, it's getting a lot easier to quickly spot whether or not the lead outs are in the rigth place, if there's enough tip weight,  are the wings level, does the engnie run the same uprigth/inverted, etc.  Only if the ship feels comfortable will I fly a whole pattern on the first flight.   I'm not an expert at all this..........yet!  But it is easier than it was to start seeing things quicker.  Even though you might not believe it if you saw me, I don't like a LOT of line tension.  I just want enough to feel that the control inputs are "solid". 

To tell a *little* embarrising story on myself, I had my newly refinsihed Parrott P-47 at the last contest last season.  I was flying it in Classic about 10-12 years ago, and decided it needed to go on Weight Watchers!  After several years of on and off work to it, It is about 4 oz. lighter, adn sports a MCC oy Rh 40 in place of the Fox 35 it had.  As soon as it broke ground I knew it was going to fly better.  But, I had a bit of a scare on the reverse wingover!  The outboard tip flipped up a couple of times.  No immediate danger of losing it, but it was getting light in the manuevers.  After the flight, I noticed something I had missed in my zeal and haste.  I had not replaced the wing tip weight!  Flying 5.3-5.4 laps on 62 eye to eye lines and no tip weight!  Needless to say, I felt prety STUPID!  But it was much better when I put the weight in it.  That design (1965) has an airfoiled verticle fin as did the original Noblers.