Composite-ARF Impact question

[J.Oddino]

Adam, I agree.  I took a close look at my Impact.  Here are some
observations regarding the vertical stab:
The seam is not on the centerline.
The airfoil is symmetrical.
The trailing edge at the top is twisted to the right.
It is not a design feature and needs to be fixed.

The question is how do you fix it?
I can hold it in the right position but I'm not sure how to clamp it there.
It is also not obvious that if you could hold it or clamp it while you glued
in the rudder post it would stay where you wanted it.  I'd like to be able
to put in the right kind of structure to fix it before putting in the rudder
post.  Any ideas out there?
Regards, Jim

----- Original Message ----- 
From: "Adam Quennoz" <aquennoz at ipa.net>
To: <discussion at nsrca.org>
Sent: Monday, January 31, 2005 5:02 PM
Subject: Re: Composite-ARF Impact question


> I've done some more investigating.  I traced the outline of the airfoil
> on top of the v. stab on a piece of paper.  It is symmetrical.   Now the
> kicker....  I drew a centerline on the top of the stab.  Then stood
> behind the plane and sighted down the line I made.  It pointed WAY off
> to the left.  So there is definately something going on with the
> vertical stab.  I still can't figure out if it's a design feature or a
> mistake.  I guess the question to ask is if anyone out there flying this
> plane notice any difficulty in trimming or anything out of the ordinary
> while trimming?  I'm also curious what Jason Shulman has to say about
> this.  Does he know it is there?
>
> Regards,
> Adam Q
>
> Bill Glaze wrote:
>
> >
> > As I recall, this thread started because of one flyer noticing the
> > asymmetrical airfoil on his new fuselage. While certainly not original
> > in aviation, I must admit that I've not seen this before in the
> > modeling world.  Or, probably, it's just that I've not noticed it
> > before.  I sure hope he keeps us updated as to how it works in the
> > real world of modeling.
> >
> > Bill Glaze
> >
> > Bob Richards wrote:
> >
> >> Bill,
> >>
> >> I don't think it is uncommon for full-scale planes to have offset or
> >> asymmetrical fins. However, they are designed with the right amount
> >> *for cruise*. Any other speed/power setting will change things. Since
> >> they are after the most efficiency in cruise conditions (better
> >> range), they will probably want the least amount of offset thrust as
> >> possible, and will trim the rudder/fin accordingly. If they expect
> >> the fin to be providing a constant yaw force, it would make sense to
> >> give it an asymmetrical airfoil for the most efficiency. Let the
> >> pilots deal with the other situations.
> >>
> >> I personally think the right-thrust is the correct way to go. I can't
> >> argue with what others have said about throttle mix working for them,
> >> but I don't see how it would work. I think you will have less
> >> slipstream effect happening at full throttle in level flight than you
> >> would at full throttle in a climb. As the prop unloads with
> >> increasing airspeed, the slipstream effect should decrease.
> >>
> >> Of course, I remember the very detailed trim instructions that came
> >> with my Great Planes Cap21. Something like: "Pull the nose up until
> >> pefectly vertical. If the plane yaws off to the left, add weight to
> >> the right wingtip". There was no mention ANYWHERE about engine
> >> thrust. Tossed that in the trash. :-)
> >>
> >> Bob R.
> >>
> >> */Bill Glaze <billglaze at triad.rr.com>/* wrote:
> >>
> >>     Adam:
> >>     This may be a little bit off the mark, but just a little bit.
During
> >>     WW2, the Italian firm Fiat produced a very good series of
> >>     fighters with
> >>     exactly the characteristics you mention, that is, an asymmetrical
> >>     fin/rudder airfoil. Seemed to work well for them; other nations
> >>     handled
> >>     the problem differently.
> >>     Bill Glaze
> >>
> >>
> >>
> >> Bob Richards
> >> bob at toprudder.com
> >> http://www.toprudder.com
> >
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