At 04:42 01 February 2013, Larry Suter wrote:
In his article on avoiding PIO in Grob 103's,

http://www.soaringsafety.org/pilots/ic8.htm

Dean Carswell writes, "the more the airbrakes are closed, the less pitch
st=
ability the Grob will have, making a PIO more likely if otherwise
mishandle=
d"

Is there a simple explanation why opening the spoilers increases the
pitch
=
stability? Does it somehow move the center of lift further aft? I believe
i=
ncreasing the separation between the cg and center of lift is the classic
w=
ay to increase pitch stability.=20

And if that's how it works, why does the center of lift move aft? I would
g=
uess spoilers destroy the lift downwind of their location, causing the
cent=
er of lift to move forward.....

Thanks,
Larry


I have flown a G103 II Acro in Belgium and Germany many times and in lots
of different conditions. It is a common 2 seat trainer and cross country
machine in Europe. Its stability is legendary. I have never heard of anyone
having a PIO or experienced one myself. I would assess it as the glider
type that is least likely to have a PIO. (I fly an all flying tail Std
Cirrus). As the article states, a proper approach speed, a well held off
landing and all will be well. I you do have a bounce then hold the
controls steady as you would for any other glider, certainly don't adjust
the air brakes and let the air speed decay until you touch down properly.
Gavin
Std Cirrus, G-SCNN, #173
LSV Viersen, Keiheuvel, Belgium