holy smokes YouTube landing

"bumper" wrote in message
...

"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..

(really important stuff snipped)

The
Genesis "T" tail is actually a hinderance.
Bill Daniels




I bet not nearly the "hindrance" as would occur if you attempt to fly the
Genesis without that horizontal stab.

bumper
"Dare to be different . . . circle in sink"
QV and MKII

Of course, an existing Genesis won't fly without the tail. But the Genesis
CONCEPT could have as evidenced by Jim Marske's designs.

Bill Daniels

"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..

Of course, an existing Genesis won't fly without the tail. But the
Genesis CONCEPT could have as evidenced by Jim Marske's designs.

Bill Daniels


Would the resulting aircraft perform better than the much more numerous and
seemingly more successful "standard" planform?

While I admire experimenting and innovation, I wonder why, if the flying
wing concept were so good, at least as applied to gliders, hasn't it been
embraced by major manufacturers? They seem willing to go to great lengths to
eek out as much performance as they can. Could it be that the tweaks needed
to impart longitudinal stability, like reflexed trailing edges, are not
efficient enough over a broad enough speed range?

bumper
Minden, NV

Master Bumper

You are indeed correct. The Akavlieg Braunschweig tried this with the quite
radical SB13 prototype. This Standard-Class glider first flew in 1988. Lots of
details in Dr Fred Thomas' "Fundamentals of Sailplane Design.
15m wingspan, 15 degree sweep, elevons and winglets doubling as vertical
stabilisers. Differential deflection of rudders on the winglets to counter yaw.

It proved to have similar performance to contemporary standard class
gliders.Some advantage in efficiency being generally lost to handling induced
inefficiency. So - There was no compelling efficiency advantage. Conversely
there were substantial operational and controllability issues and high pilot
work load. etc...

For example; It proved impossible to winch launch safely. Apparently
Braunschweig has used the SB13 in contests, and also allows experienced akavlieg
pilots to fly it. There are quotes like "it exhibits very poor flying and
handling qualities in turbulent conditions." It is the subject of at least one
thesis on aeroelastic properties.

Details at:

http://www.akaflieg-braunschweig.de/prototypen/sb13/

And here -

http://www.sailplanedirectory.com/braunsch.htm#SB-13

The Genesis is a more modern design, and presumably learned from the
difficulties they had with the SB13 - which was after all a prototype designed
to investigate innovation, rather than a commercial endeavor.

There have been others with a similar idea, in fact the SB13 was not the first I
know of at improving on the Horten - the BKB1 has that honour. Although the
information is unsubstantiated - there is some info here
http://www.astercity.net/~krisabc/BK...hocki3-en.html

Maybe Jim Marske will develop a giant killer from this concept - but I
personally can't see it happening. It is a fascinating concept -and so we keep
trying to minimise the tail boom (cf Diana 2) But it remains the best way to do
things. Consider - Even Burt Rutan eventually went back to the conventional
layout with the Global Flyer (http://www.scaled.com/projects/globalflyer.html) -
it is not conventional for nothing - it represents the best compromise.

My 2 (South African ) cents worth - not that that means much at ZAR 7 / USD but
there you have it.

bumper wrote:
"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..
Of course, an existing Genesis won't fly without the tail. But the
Genesis CONCEPT could have as evidenced by Jim Marske's designs.

Bill Daniels


Would the resulting aircraft perform better than the much more numerous and
seemingly more successful "standard" planform?

While I admire experimenting and innovation, I wonder why, if the flying
wing concept were so good, at least as applied to gliders, hasn't it been
embraced by major manufacturers? They seem willing to go to great lengths to
eek out as much performance as they can. Could it be that the tweaks needed
to impart longitudinal stability, like reflexed trailing edges, are not
efficient enough over a broad enough speed range?

bumper
Minden, NV

It proved to have similar performance to contemporary standard class
gliders.Some advantage in efficiency being generally lost to handling
induced inefficiency. So - There was no compelling efficiency
advantage.

It should be noted that most all hang gliders are flying wings. The
reason for this has more to do with portability than with performance.
The handling quality of many hang gliders since, say the early '80, are
quite pleasant - remember, this is weight shift contol.

Tony V

"bumper" wrote in message
...

"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..

Of course, an existing Genesis won't fly without the tail. But the
Genesis CONCEPT could have as evidenced by Jim Marske's designs.

Bill Daniels


Would the resulting aircraft perform better than the much more numerous
and seemingly more successful "standard" planform?

While I admire experimenting and innovation, I wonder why, if the flying
wing concept were so good, at least as applied to gliders, hasn't it been
embraced by major manufacturers? They seem willing to go to great lengths
to eek out as much performance as they can. Could it be that the tweaks
needed to impart longitudinal stability, like reflexed trailing edges, are
not efficient enough over a broad enough speed range?

bumper
Minden, NV

The answer to your questions is that we really don't know. There are good
people on both sides of the arguement.

The thing with all flying wings both the swept variety and the straight or
slightly swept forward is that there isn't the long history of incremental
development. Designers have found it expedient to just keep tweaking the
conventional tailboom design to get another small increment of performance.
This has led to a huge body of knowledge about that approach. The body of
knowledge about flying wings is far smaller thus the development risks are
much higher.

There are two things that might change that. First, there just doesn't seem
to be much more performance to extract out of the conventional approach so
designers may start taking risks with more radical approaches. Second, the
state of Computational Fluid Dynamics (CFD) has reached the point where it
can reduce the risks of a radical design.

Another problem with the history of flying wing designs is that the typical
pilot doesn't understand the subtile details of what makes a flying wing
work well. If a particular flying wing design doesn't turn out to be a
world beater due to some small fixable detail. The general response will be
to condem the whole flying wing idea. This has discouraged a lot of
designers from even trying.

Still, the lure is there. In any reasonable comparison, the flying wing
will have lower parasitic drag and the overall structure will be more
robust. That inherent robustness is like money in the bank to a designer.
He can spend it on things like smoother skins, higher Va speeds or lighter
wings panels.

The advantage to most of us, should the designer begin to try flying wings,
is that it would be an exciting thing to see after all these years of
look-alike pod and boom designs.

Bill Daniels

"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..
The advantage to most of us, should the designer begin to try flying
wings, is that it would be an exciting thing to see after all these years
of look-alike pod and boom designs.

Bill Daniels


Which most are you referring to? I haven't seen a flying wing that
approaches the grace and beauty of some of the current designs which are
just about the prettiest things flying . . . right after some of the
feathered critters.

bumper
ASH26E - - pod, boom, and gorgeous
Minden NV