Conference vmszoo::rc

If you're at the point where you can correct it, do it!

You'll notice it with the covering on even more and you'll never be happy with
the way it looks. I had a model that I built with the stab out of line and it
never trimmed properly UNTIL I CRASHED IT AND REBUILT THE REAR OF THE FUSELAGE!

If you caught it this early and haven't continued yet, fix it.

Joe,

If your not to far out of true it may be possible to shim the 
stablilzer.  You will notice the plans tell you to glue the stablizer so 
that it straight with the wing, not the fuse.

Another technique I saw discussed under the Chipmunk note was to wet 
down the fuse and try and twist it back.  It didn't work for the 
chipmunk but may be worth a try.  Finally, you may have to do some 
serious wood carving.  Take a look at the chipmunk note 
(DIR/TITLE="chipmunk").

Loren

    I had this same problem with a 1/5 scale Bird dog.  Here's what I did:
    
    Strip whatever wood you can (i.e. - planking.  I suspect you can't
    really do that in your case though) I then mounted what was left
    in a vise held jig (using 2x4's, believe it or not!) forcibly twisting
    out the misalignment.  Then liberally soak everything down to soften
    the wood, and while all is still in the jig, add whatever new wood 
    you can (in my case, more planking).  It's the new wood that's going
    to hold all in place.  Let dry, soak again and let dry.  It did the 
    trick for me.  I can't begin to describe the jig.  It was sticks, 
    rubber bands, external props, masking tapes, etc., etc.
    
    Basically, it was a single long 2x4, held in the vice which served as
    the straight line/base line, and all else somehow attached, by hook, 
    nail, and grim - to it.  Well ! I don't know if that helps, but I
    do agree with others - it must be fixed.
    
    john

Joe,

From experience I can say that a minor twist in the tail isn't much of a 
problem in your basic trainer type airplane. If its not more that a couple
of degrees and you can live with it aesthetically (did I get that right?) don't
worry about it. It should fly fine. You may notice that it won't track true
through a loop, but you won't be worrying much about that for a while anyway.
My first couple of planes had pronounced twist at the tail and all flew fine.
(As a side note, I'm getting better and my Panic is dead square)

Have you built the wing yet? If so set it and the stab in place and see if
they are parallel. If they are or are pretty close you shouldn't have any
trouble at all. Wing and stab parallel and fin perpendicular to both is more
important than their relationship to the fuse.


I haven't found any of the twisting remedies to be fairly successful, and
cutting a fuse apart to fix a minor twist is not an experiance I'd recommend to
someone building their first plane.

Good luck in any case,
Randy

    Joe,
    
    I'm afraid I have to agree with Randy.  A minor twist in the aft
    fuselage really causes very little (if any) problem as long as the stab
    is aligned parallel to the wing and the fin/rudder perpendicular to the
    stab.  I had an old (lasted over 13-years) Ugly Stik that had  a
    terribly twister fuse acquired from years of water flying and it always
    flew just fine, even with the stab crooked.  Eventually, I refurbished
    the bird and squared away the stab; the airplane flew a bit better but,
    mainly, it _looked_ better in flight.  Other than that, it'd have been
    perfectly happy to fly with a cock-eyed stab for the rest of its life.
    
    What you have here is a matter of effort vs. gain.  I heartily concur
    that drastic or intensive efforts to straighten the fuse will provide
    little more than an aesthetic improvement in the bird and, if this is
    to be yer' first/trainer airplane, it's just not worth the effort.  I'd
    only advise straightening the fuse if it involved a minimum of
    work/hassle and it sounds as if this may not be the case.  Therefore, I
    recommend squaring away the flying surfaces and forgetting about the
    twist.  I guarantee it won't be visible at 25-yards from the back of a
    galloping horse!  :B^)  Seriously, you'll be so thrilled/busy at flying
    yer' own creation that I'd bet you'll never see the goof in the air and
    will shortly forget about it in any case.  Don't tell anyone and they
    probably won't notice it either.    

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    I be the living proof, since it was my Chipmunk that was mentioned
    earlier.  I never did get the twist out, so I sanded and shimmed
    the fuse so the horizontal stab was square to the wings.  If you
    get down on the ground behind the plane and look towards the prop
    you will definetly see the twist, but thats the only noticeable
    way of spotting it.  It flys very straight and doesn't seem to add
    any unwanted flying characteristics to the flight.
    
    Ken

    Thanks for all the advice.  Here's a quick update.
    
    Since the twist only appeared to be a few degrees, I decided to use the
    water/counter-twisting method.  I dipped the rear 12" of the fuse in
    HOT water.  Then I clamped the cabin section of the fuse (where the
    sides are parallel) in the vise, and placed a big C clamp over the very
    last piece of the fuse, lightly tightening it to avoid crushing it. 
    To create a counter-twisting torque, I then hung a heavy wrench
    suspended by a string over the end of the C clamp.  Worked like a
    charm, just giving enough compensating twist in the other direction.  I
    let it dry overnight, and looked at it this morning...it appears to
    have less than half the twist it had before.  I'll probably repeat the
    process again to get it all out.  On the other hand, from the comments
    made earlier, just a little sanding will make the stab parallel to the
    wing, so I may not bother.
    
    I learned something on this one.
    
    Thanks,
    Joe
    

    FROM BACK IN THE DAYS OF RADIO DISTURBED FREE FLIGHT (OR) MULTI
    CHANNEL "REED" RADIOS WITH "OPEN-LOOP" SERVOS.........
    
    For those of you who may have heard of JERRY NELSON (US Team Member
    at the RC INTERNATIONALS of 1963(?) and 5th placer):
    
    Jerry had a kitted design called the SULTAN. For some reason (Jerry
    ordinarily built and rebuilt beautiful aircraft) his personal ship
    had a stabilizer that was as crooked as they can get, both stabilizer
    and fin. He flew it this way at contests and WON. And on reeds,
    there ain't no holding in trim to compensate; the darn thing just
    tracked like on a rail. I might say that my Sultan, another one
    at Hickam AFB and all the other North and South California Sultans
    had stright tail feathers and they all also tracked nice.
    
    Must have repeeeeeld the laws of astrodynamics.
    
    don

    I guess I spoke too soon.  Last night when I started working on it
    again, the original amount of twist was back.  I then decided that
    water ain't the solution, at least not long-term.  Since the problem
    was mainly restricted to the stab platform, I de-bonded one joint
    between it and the left fuse side.  Now, with the joint open, I did a
    little cutting here and there to make the joint fit better.  After
    regluing and holding the aft end in the propor orientation, it dried up
    quite straight.  After sanding a little to make the stab surface nice
    and smooth, a test with a level told me it was dead nuts on!  Problem
    solved, and it didn't really take all that much work.
    
    On to the engine mount........
    
    -Joe

        Re:                      <<< Note 1185.9 by WAV14::MARRONE >>>

        Joe,
        
                You are  right,  water  isn't  the  answer.    But window
        cleaner is!   "Borrow"  your  wife's  window  cleaner,  spray the
        entire fuse and then twist  it  so  much  that  there is a slight
        twist in the opposite direction.   Tthen  let  it  dry overnight.
        Why  window  cleaner?  It contains ammonia, which  softens  balsa
        wood.
        
        Anker

    
    re: .9
    I think you made the right decision taking the time to fix it, given
    that it wasn't a major overhaul.  I know personally I'd keep looking
    at it and wishing I'd fixed it, even if it didn't affect the flight
    characteristics.  Maybe I'm too picky!
    
    P.S. Anker, this is a plywood fuse, so even ammonia might not do the
    	 trick???

    Re: a few notes back....yes, the fuse IS plywood, so would the window
    cleaner method work?  
    
    Even if it does, I am now convinced that if a repair can be done
    without compromising the integrity of everything, then that's the right
    way to go.
    
    The work has slowed down a bit because I'm waiting for some
    mail-ordered monokote from Tower.
    
    -Joe

    Just to go back and add to some comments I made in reply >.3
    
    I think I agree with both those that say fix it, and those who
    say don't bother - depending on other factors.
    
    I'm sure that my method worked so well only because I had the
    opportunity to add NEW wood (turtledeck planking) while the fuse
    was jig'd.  This prevented "Memory" from being a factor.  Also a
    factor, this is a scale ship and I couldn't tolerate a twist, at
    any price.  Another thing - although balsa and plywood were inv-
    olved, I did lace the water spray liberally with an ammonia clean-
    ing agent (about 50/50).  That does help!.
    
    Incidentally, the reason why the twist got in, in the first place
    was that I paid too much attention to aligning the very aft end of
    the fuse so that the sticks "Matched".  I should have used my eye-
    ball on the rest of the fuse - let the end sticks "Mismatch" until
    such time as everything set up, then make my corrections at the
    tail end only (a little cutting - a little filling).  Would have
    been, by comparison, a lot simpler.         For what it's worth ?
    john