I wish I'd never got into this...

(Chris OCallaghan) wrote in message om...
Well, at least we've got everyone on the same theme now. It's the
drag. Why don't you guys in Phoenix do a little testing and we'll do
the same here at M-ASA. I think we all agree that the heavier glider
has a significant drag advantage at high speed, and will gain
additional altitude. But how much, exactly?


So far I have not seen anyone consider the fact that, at the same
(high) speed, the unballasted glider has a significantly higher sink
rate at the start of the pull up. The initial conditions are not the
same.


Andy (GY)

"Andy Durbin" wrote in message
om...
(Chris OCallaghan) wrote in message
om...
Well, at least we've got everyone on the same theme now. It's the
drag. Why don't you guys in Phoenix do a little testing and we'll do
the same here at M-ASA. I think we all agree that the heavier glider
has a significant drag advantage at high speed, and will gain
additional altitude. But how much, exactly?


So far I have not seen anyone consider the fact that, at the same
(high) speed, the unballasted glider has a significantly higher sink
rate at the start of the pull up. The initial conditions are not the
same.


Andy (GY)

The sink rate for the fully loaded glider(190 litres) = 1.2m/s
for the none ballaste version 1.65m/s

Udo

Udo Rumpf wrote:
The sink rate for the fully loaded glider(190 litres) = 1.2m/s
for the none ballaste version 1.65m/s

And the vertical kinetic energy converted to altitude (the only place
where we can take the energy in a glider) would be
h=v^2/(2g)
so for 1.2 and 1.65 m/s the altitude losses would be
0.073 and 0.139 m respectively. Not a signifigant factor I would say.

Plus, we would have to take into account the fact that in the end as
well (after levelling out) their sink rates will be different. But still
no signifigant effect...

Jere

jere at iki.fi

Andy,

Sink rate and drag are the same thing (we need to burn something to
feed friction... it's our potential energy we're paying out). See my
other posts on AOA and wing loading. That's right, the initial
conditions are not the same, which is why we carry water and why a
ballasted glider will gain more height during a pull up from high
speed.

We're in the same place.


(Andy Durbin) wrote in message . com...
(Chris OCallaghan) wrote in message om...
Well, at least we've got everyone on the same theme now. It's the
drag. Why don't you guys in Phoenix do a little testing and we'll do
the same here at M-ASA. I think we all agree that the heavier glider
has a significant drag advantage at high speed, and will gain
additional altitude. But how much, exactly?


So far I have not seen anyone consider the fact that, at the same
(high) speed, the unballasted glider has a significantly higher sink
rate at the start of the pull up. The initial conditions are not the
same.


Andy (GY)