Ventus C rigging

John Orton wrote:
I have corrected this problem on unflapped gliders before. On one glider in
particular one aileron had a bit more undercamber than the other due some
damage. The temporary fix was to add a small trim tab on the trailing edge
of the aileron. It worked! The aileron was subsequently fixed due to another
repair.
It always came down to a twist, bend or some damage of the aileron. The
reasoning is; If the aileron rigging was wrong and with the stick central
and the left was down further than the right. Then when flying if the stick
was held central then a roll would result. If it was flown hands off then
the ailerons would balance at a nuetral posiotn and it would fly level.
Hence if the pilot is having to apply side stick loads whilst in flight it
can not be due to incorrect lenght of pushrods and rigging and must be due
to twists or some such. This of course does not hold if there are
centralising springs or dampers that are set up. However if the stick loads
increase with speed as described then it is centainly not due to springs or
dampers.
Of course flaps being set differently on each side would give rise to the
same sort of characteristics as a twist or bend.

Also I would have to agree to check the mylar seals and such like they do
have dramatice effects if they are loose.



"James Hamilton" wrote in message
...

I have a 1987 Ventus C that I purchased in 1995. Love
the plane but it wants to roll to the right at high
speeds (90kts or greater). Actually I guess it always
wants to roll to the right but I start to notice how
much left aileron pressure I have to apply to counter
the roll at the higher speeds, especially above 100kts,
for any period of time (long final glide). It makes
my arm tired. At speeds below 80kts I don't notice
it. I have tried various riggings with the flaps/ailerons
but other than slight improvements I don't seem to
be making any progress and have just 'lived with it'
over the years. I'm afraid that the problem might
be 'built-in' to the airframe with one wing having
a different angle of incidence than the other. I sent
an email to Schempp-Hirth about this and never got
a reply. Anyone have any ideas?

Jimmy Hamilton
Reno, NV
JLH






As John commented any aerofoil discrepancy will result in progressively
different forces. If there is any damage history on the wings or reprofiling
history, this would be a place to look.

Assuming this is not the case - Just a thought, but have you looked at the wings
when you are applying the force. The Schempp-Hirth airbrake caps are spring
loaded, over time the springs weaken and you may have assymetric protrusion.

Similarly they lock down from the outside in - if the over centre is not
symmetrical you could have the same effect. Not sure how this is set on the
Ventus, on the Cirrus it is by rotating tie rod ends in the fuselage, so it
would be easy to have different tension left to right.

At high speed these would introduce significant forces with the slightest
differences.