Rudder counterbalance ?

[Atwood, Mark]

Well...I can certainly speak to needing this in the Rev Pro...which I'm
guessing isn't a whole lot different than the Impact in construction.
The fuselage buckled and snapped in half in flight (and yes...it still
managed to fly to the ground with relatively little damage).  Added the
light (4gm) "Ladder" crutch plate behind the wing and no problems at
all.

I have a photo of the brace if someone is interested...contact me
offline.

-Mark

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]
On Behalf Of Wayne Galligan
Sent: Thursday, April 28, 2005 2:26 PM
To: discussion at nsrca.org
Subject: Re: Rudder counterbalance ?

I have had conversations with a few people that own these airframes
(Impact)and they along with a few others have strengthened the fuse in
two
ways.  A ladder  type frame in the fuse from the wing t.e back to the
stab
area and another put a stiffener(former) at the front of the wing area
to
decrease the possibility of compression of the fuse in this area.  It is
believed that compression of the fuse in this area contributes to a wave
progression all the way back to the tail section.  The tail section
being
the smallest and weakest area gets whipped and eventually the fuse
breaks or
contributes to tail feather flutters.

>From what I've heard....  FWIW

WG


----- Original Message ----- 
From: "Peter Pennisi" <pentagon.systems at bigpond.com>
To: <discussion at nsrca.org>
Sent: Thursday, April 28, 2005 4:29 AM
Subject: Rudder counterbalance ?


>
>
> Hi all,
>
>
> Most of you would be aware that a number of Composite ARF "IMPACT"
have
> failed from suspected rudder flutter.
>
>
> I raise a couple of questions to this forum;
>
>
> I know that the purposes of counterbalances are to reduce the loads on
> servos and linkages in our application but what are the side effects.
>
> Can a rudder counterbalance create undesired torsional stresses on the
> fuselage?
>
> Can a poorly configured and tensioned pull-pull linkage to the rudder
be
> more susceptible to flutter if the rudder has a counterbalance?
>
> What other types of forces are at play with counterbalances?
>
> I am just trying to find a reason for the relatively high failure
rates
> against this design.
>
> It is the same old thing- why are some people having problems and
others
> don't. (Similar story to 4-stroke exhaust headers)
>
> I will be test flying my model soon so I am obviously concerned.
>
> Regards,
>
> Peter
>
>
>
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