At 03:01 02 June 2011, at wrote:
On 1/06/2011 6:23 AM, Carl Baxter wrote:
I'm trying to make sense of the weight and balance section in the
ASK-21 manual but having no success. They give an equation for r sub
R, which I assume is the empty CG, but it's not specifically called
out. The units don't balance; there is length on one side of the
equation and length squared on the other. There is an example given
for calculating "inflight CG" and the results seem to be out of
limits but they don't comment so I'm not sure I've got that right.
There is a Load Envelop with Empty Weight on the abscissa and r sub R
on the ordinate. Where does the in flight CG come in? Or is r sub R
also the inflight CG

At 360kg (the nominal empty weight of the aircraft) there is only 8 mm
of CG range within the envelop. Is it really that small? I
understand the Schweizer weight and balance calculations but the
English translation of the Schleicher manual has me puzzled.

Any help would be appreciated. Thanks.

Carl

Carl

The BGA web site has Data sheets for many gliders that are very helpful.

They can be found at
http://www.gliding.co.uk/bgainfo/tec...datasheets.htm

John


I have made up a spreadsheet to show where the C of G is for our K21,
especially useful when using spin wieghts.

The C of G range in mm is
Spinning
Forward limit 234
Forward of 315 Does not spin
320 to385 322 to 385 Incipient
aft 400 400 Sustained spins
Aft limit 469

Flying with the weights confirmed the manual, it was not possible to spin
with the C of G forward of 315 mm
It would incipient with the C of G between 322 and 385.

Being heavy I could not get the C of G aft of 400 to sustain a spin.

If you want a copy of the spread sheet drop me a mail

Regards
Max