L/D max of Valkyrie (the big fella)

[[email protected]]

Quite a lot of sources name the Valkyrie as an extremely high lift
over drag efficient aircraft. According to Wikipedia:

"This gave the Valkyrie the best lift:drag ratio of any powered manned
aircraft ever built and allowed a much better aspect ratio on take-off
and landing. Some recent SST designs are considering this as an
option."

Anyone knows l/dmax of the XB-70? Commercial airliners are around 1:18
while motorgliders (and the U2) come close to 1:30 An L/D of 1:30
seems impossible for an aircraft like the Valkyrie?

[ChuckSlusarczyk]

In article . com>,
says...
>
>Quite a lot of sources name the Valkyrie as an extremely high lift
>over drag efficient aircraft. According to Wikipedia:
>
>"This gave the Valkyrie the best lift:drag ratio of any powered manned
>aircraft ever built and allowed a much better aspect ratio on take-off
>and landing. Some recent SST designs are considering this as an
>option."
>
>Anyone knows l/dmax of the XB-70? Commercial airliners are around 1:18
>while motorgliders (and the U2) come close to 1:30 An L/D of 1:30
>seems impossible for an aircraft like the Valkyrie?

Good question I have some B-70 data somewhere around from when I worked at NASA
Lewis (now Glenn) on the B-70 project. I worked in the 10'X10' wind tunnel and
we had the B-70 model in for inlet studies. North American had a nice booklet
they passed out that had a lot of neat pics and background on the plane.

Chuck S

[Dan[_2_]]

wrote:
> Quite a lot of sources name the Valkyrie as an extremely high lift
> over drag efficient aircraft. According to Wikipedia:
>
> "This gave the Valkyrie the best lift:drag ratio of any powered manned
> aircraft ever built and allowed a much better aspect ratio on take-off
> and landing. Some recent SST designs are considering this as an
> option."
>
> Anyone knows l/dmax of the XB-70? Commercial airliners are around 1:18
> while motorgliders (and the U2) come close to 1:30 An L/D of 1:30
> seems impossible for an aircraft like the Valkyrie?
>
You might try asking this in rec.aviation.military.

Dan, U.S. Air Force, retired

[J.Kahn]

wrote:
> Quite a lot of sources name the Valkyrie as an extremely high lift
> over drag efficient aircraft. According to Wikipedia:
>
> "This gave the Valkyrie the best lift:drag ratio of any powered manned
> aircraft ever built and allowed a much better aspect ratio on take-off
> and landing. Some recent SST designs are considering this as an
> option."
>
> Anyone knows l/dmax of the XB-70? Commercial airliners are around 1:18
> while motorgliders (and the U2) come close to 1:30 An L/D of 1:30
> seems impossible for an aircraft like the Valkyrie?
>

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.

John

[Marc J. Zeitlin]

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/~portwin/ASTRA/X_craft/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/waverider/design.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

[Bill Daniels]

"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

[ChuckSlusarczyk]

In article >, J.Kahn says...
>
wrote:
>> Quite a lot of sources name the Valkyrie as an extremely high lift
>> over drag efficient aircraft. According to Wikipedia:
>>
>> "This gave the Valkyrie the best lift:drag ratio of any powered manned
>> aircraft ever built and allowed a much better aspect ratio on take-off
>> and landing. Some recent SST designs are considering this as an
>> option."
>>
>> Anyone knows l/dmax of the XB-70? Commercial airliners are around 1:18
>> while motorgliders (and the U2) come close to 1:30 An L/D of 1:30
>> seems impossible for an aircraft like the Valkyrie?
>>
>
>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.

It would ride the shock wave only when the wing tips were drooped if I remember
correctly,don't know it it ever went supersonic with the tips up.But it was a
good gimmick.

Chuck S

[Denny]

The Valkyrie is still one of the most beautiful aircraft ever
built... Everytime I walk up to her, I shake my head in wonder... It
never gets old...

Ya, ya, ya, I know, I know - she handled like a pig below Mach 1, she
couldn't be maneuvered, she sucked fuel like a volcano, at Mach 3
straight ahead she was a sitting duck for Soviet missiles, she was
unreliable, she was high high maintenance, she responded only to a
very skilled hand ... In short she was like taking a Las Vegas
stripper home to meet your methodist mom in Iowa... But, gawd was she
a thrill...

denny

[Montblack]

("Denny" wrote)
> ... In short she was like taking a Las Vegas stripper home to meet your
> methodist mom in Iowa... But, gawd was she a thrill...


Ma, I got me a girl out here in Las Vegas. We're flying home today, so she
can meet everyone.

Gotta go Ma, the plane's taking off... we'll see you all in, what, half an
hour?


Montblack

[wright1902glider]

My plane once held the world record for L/D at 7.3:1! Not bad for
105 years ago, and still better than the early Regallos.

Harry