When you add weight to an aircraft ... all points on the polar shift to
the right. i.e. minimum stall increases ... the speed for minimum sink
increases ... the speed for best L/D increases ... all almost the same
magnitude at the speeds we typically fly at.

So, if your L/D was 10:1 at 60 MPH when empty ... when loaded to gross
it could be 10:1 .... but at 75 mph. So, if you were gliding from a
mile up in a no wind situation ... you would go 10 miles distance in
both cases ... but, of course, at a higher speed and in less time if
you were heavy.



Larry Dighera wrote:
On Sat, 26 Feb 2005 14:48:17 -0500, "news.mcgraw-hill.com"
wrote in
::

During a review of the V-speeds for an airplane I've never flown
before, my
instructor asked me about glide speed vs. weight, and total glide
distance.

I got the glide speed vs. weight part right, but the distance part
seemed
counterintuitive - that the total distance covered (by flying at the
correct
best glide speed for the weight) would be the same, regardless of
the
weight.

Can anyone explain this so that it makes sense?


Here's a clue:
http://www.av8n.com/how/htm/power.ht...weight-effects

The short answer is that the L/D is virtually unaffected by weight.

For a more technical explanation, I've crossposted to
rec.aviation.soaring.