L/D max of Valkyrie (the big fella)

J.Kahn wrote:

The normal subsonic LD would be very low, about 6 or 7 to 1 at best. The
supersonic shockwave riding phenomenon they are talking about is
something else though and could I guess be true, although it's
surprising no other supersonic a/c has tried to exploit it.

The note in Wikipedia regarding the L/D for the XB-70 says:

"There is a popular belief and some sources claim that this helps the
XB-70 have the highest lift-to-drag ratio on a powered, manned
aircraft.[2]", so they clearly state that someone else believes it,
but they make no claim to the truth of it.

Now, note [2] points to:

http://easyweb.easynet.co.uk/~portwi...ft/xb_70a.html

which says:

"Overall, the XB-70 has the best lift-to-drag ratio of any manned
airplane ever built, being bettered only on the unmanned S-21 drone..."

As Mr. Kahn points out, the L/D of this aircraft subsonically will be
well below 10, which is nothing to speak of. Supersonically, we can
reference:

http://www.aerospaceweb.org/design/w...shtml#complift

which indicates that at Mach 3, we can expect L/D ratios of 5-6, max.
for aircraft using compression lift. Now, that's pretty good for
supersonic flight, and if the claims above had said "the best L/D
ratio of any manned SUPERSONIC aircraft", it would probably be true.

But it's clearly not the highest L/D of any manned aircraft - my COZY
MKIV has a glide ratio of about 14:1, which I proved just last
December by losing my propeller and gliding down 17 NM to L64 from
9500 ft. Gliders, of course, are much higher - up to 50:1, or even
better.

--
Marc J. Zeitlin
http://www.cozybuilders.org/
Copyright (c) 2007

"Marc J. Zeitlin" wrote in message
...
Gliders, of course, are much higher - up to 50:1, or even
better.

The 31 meter span ETA is reported to have an L/D of about 75:1. These
extremely large wingspan gliders are very hard test for L/D since tiny
vertical motions in the atmosphere create too much noise in the data.

In any event, whether the glide path rises or falls is far more likely to be
caused by atmospheric motions than by the glider's performance. They are as
close to perpetual motion machines as has been developed.

Bill Daniels