Composite-ARF Impact question

Mon Jan 31 06:34:30 AKST 2005

I am currently building an IMPACT. My model also features the of-centre join
line. I have had a good look at mine and the fin appears symmetrical to me. 

I believe the of-centre join line is due to manufacturing. This doesn't mean
the model is crooked.

If anyone has ever made a mould before one of the steps in making the mould
is to position a flange board around the plug. In this instance the board
was not exactly centred at the fin. There is a little tolerance in this area
so I would not be concerned about it.

Try putting a little trim tape down the centre of the fuse and over the fin.
Make sure it is centred to the fuse. Now take a look and it should look OK.
The of-centred line will just create an illusion that it is crooked.

Peter 

Peter Pennisi
Pentagon Systems QLD Pty Ltd
P.O Box 4280
Eight Mile Plains
QLD 4113
Australia
Phone:    61+0738414234
Fax:        61+0738414264
Mobile:   0408007206
Email: pentagon.systems at bigpond.com
-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On
Behalf Of rcaerobob at cox.net
Sent: Tuesday, 1 February 2005 1:19 AM
To: discussion at nsrca.org
Subject: Re: Re: Composite-ARF Impact question

We have to fly the plane.  Not compensate for assymmetric trim variables.
IMHO.

Bob P.
> 
> From: Bill Glaze <billglaze at triad.rr.com>
> Date: 2005/01/31 Mon AM 10:10:14 EST
> To: discussion at nsrca.org
> Subject: Re: Composite-ARF Impact question
> 
> We agree that any airplane is in trim for a given set of conditions 
> existing at that time.  As my primary instructor said: " the rudder is a 
> trimming device."  (Perhaps a little too simplistic, but a good starting 
> point.)
> We are constantly looking for the perfect combination that requires the 
> least work from the pilot, to achieve the most precision of results.  
> Probably a matter of taste, largely.
> 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 
> 
> 
> 

Bob Pastorello, El Reno, OK, USA
rcaerobob at cox.net
www.rcaerobats.net

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