"Koopas Ly" wrote in message
om...

I would start by considering the increase in weight as comparable to
an increase in load factor. Hence, all your aoa-related speeds would
increase by the square root of the load factor. Vs, Vx, Vy, Vglide,
etc. would all increase. Va would also go up.



I take issue with Va. At first thought, it should go up as sqrt( m/m0)
with m the new weight and m0 the maximum gross at which Va is
quoted. This since at a higher Va, we can maintain the same AOA
as we did at m0, so the G forces at stalling AOA never exceed the
design limitations.

BUT, there are 2 things (at least) which contribute to the setting of
Va in the first place. One is the limitation of 'heavy things in the plane',
such as a bag of sand in the baggage compartment. If this is the limiting
factor, then Va should indeed scale as sqrt(m/m0). However, there is
also the 'torque on the wings' (low wings) or 'force on the wings' (struts
on Cessna). If you are pulling 3.5G with a higher gross weight, you'll
be exerting more force than was designed for at certified gross.

So to be safe (hah!, we're talking about overloading dammit), then
unless you know exactly which type of failure limits Va in the first
place, you'd be best off using Va for certified gross and not scaling
it up.

--
Dr. Tony Cox
Citrus Controls Inc.
e-mail:
http://CitrusControls.com/