holy smokes YouTube landing

Bill Daniels wrote:
I think this incident may have an influence on future designs. The
Genesis
obtains excellent handling and quite respectable performance without a tail
boom which forces the question, " Why have one?" The 18 meter and larger
gliders would obtain even greater relative performance and damage resistance
since the fuselage size need not increase in porportion to wing span.

I suspect the increase in wing span might still require a commensurate
increase in rudder/fin and boom length, just to control yaw, even it
wasn't needed for the elevator. Also, flapped gliders have relatively
less drag from the elevator than aileron-only gliders, so I think they
would have still be better off because the wing could be more easily
optimized for performance.

I
wonder what the ETA would be like with the Genesis fuselage.

A further complication with the ETA is controlling the glider under
power. I have no idea how it would work out in practice, but I'm
guessing any advantages of the Genesis type design would be lessened by
the control requirements under power. Add in the problems of stabilizing
a floppy, high-aspect ratio wing, and I'm willing to believe the nod for
performance still goes to the conventional tail.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Just idle fun speculation, of course. Clearly, a conventional rudder like
the Genesis wouldn't work with a 31 meter span. But, it would take only a
tiny amount of drag at the wing tip acting through a 15 meter moment arm to
produce huge yaw moments. I've run this calculation a few times and the net
drag of tip drag rudders would acutally be less than a conventional rudder.
A trailing edge elevator would work fine regardless of the span. The
Genesis "T" tail is actually a hinderance.

As for the control moments to control engine thrust and "P" factors, yes,
that is a challenge. A few prople have suggested lowering the thrust line
so it passes through the CG and aerodynamic center. The rear propeler could
fold back somewhat like a Carat and be pulled into a tube in the rear
fuselage. Not sure how the landing gear would work with a low thrust line.

Obviously there would be some weight reduction to the 'non lifting parts'
that would roll through the wing spar calculations allowing a lighter wing.
Probably not a huge weight reduction but every bit helps the wing bending
moment.

Turning flight might be easier. The short fuselage could be kept aligned
with the local airflow easier than the very long one of the ETA.

Obviously, something like this isn't a 'cut and paste' sort of design. Each
aspect of the design would break new ground and have to be carefully thought
through. Each design change would affect everything else.

Bill Daniels


"Eric Greenwell" wrote in message
news:nmkji.6642$wu5.6324@trndny03...
Bill Daniels wrote:
I think this incident may have an influence on future designs. The
Genesis
obtains excellent handling and quite respectable performance without a
tail boom which forces the question, " Why have one?" The 18 meter and
larger gliders would obtain even greater relative performance and damage
resistance since the fuselage size need not increase in porportion to
wing span.

I suspect the increase in wing span might still require a commensurate
increase in rudder/fin and boom length, just to control yaw, even it
wasn't needed for the elevator. Also, flapped gliders have relatively less
drag from the elevator than aileron-only gliders, so I think they would
have still be better off because the wing could be more easily optimized
for performance.

I wonder what the ETA would be like with the Genesis fuselage.

A further complication with the ETA is controlling the glider under power.
I have no idea how it would work out in practice, but I'm guessing any
advantages of the Genesis type design would be lessened by the control
requirements under power. Add in the problems of stabilizing a floppy,
high-aspect ratio wing, and I'm willing to believe the nod for performance
still goes to the conventional tail.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

"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

On Jul 6, 8:56 am, "Bill Daniels" bildan@comcast-dot-net wrote:
Just idle fun speculation, of course. Clearly, a conventional rudder like
the Genesis wouldn't work with a 31 meter span. But, it would take only a
tiny amount of drag at the wing tip acting through a 15 meter moment arm to
produce huge yaw moments. I've run this calculation a few times and the net
drag of tip drag rudders would acutally be less than a conventional rudder.
A trailing edge elevator would work fine regardless of the span. The
Genesis "T" tail is actually a hinderance.

As for the control moments to control engine thrust and "P" factors, yes,
that is a challenge. A few prople have suggested lowering the thrust line
so it passes through the CG and aerodynamic center. The rear propeler could
fold back somewhat like a Carat and be pulled into a tube in the rear
fuselage. Not sure how the landing gear would work with a low thrust line.

Obviously there would be some weight reduction to the 'non lifting parts'
that would roll through the wing spar calculations allowing a lighter wing.
Probably not a huge weight reduction but every bit helps the wing bending
moment.

Turning flight might be easier. The short fuselage could be kept aligned
with the local airflow easier than the very long one of the ETA.

Obviously, something like this isn't a 'cut and paste' sort of design. Each
aspect of the design would break new ground and have to be carefully thought
through. Each design change would affect everything else.

Bill Daniels

"Eric Greenwell" wrote in message

news:nmkji.6642$wu5.6324@trndny03...



Bill Daniels wrote:
I think this incident may have an influence on future designs. The
Genesis
obtains excellent handling and quite respectable performance without a
tail boom which forces the question, " Why have one?" The 18 meter and
larger gliders would obtain even greater relative performance and damage
resistance since the fuselage size need not increase in porportion to
wing span.

I suspect the increase in wing span might still require a commensurate
increase in rudder/fin and boom length, just to control yaw, even it
wasn't needed for the elevator. Also, flapped gliders have relatively less
drag from the elevator than aileron-only gliders, so I think they would
have still be better off because the wing could be more easily optimized
for performance.

I wonder what the ETA would be like with the Genesis fuselage.

A further complication with the ETA is controlling the glider under power.
I have no idea how it would work out in practice, but I'm guessing any
advantages of the Genesis type design would be lessened by the control
requirements under power. Add in the problems of stabilizing a floppy,
high-aspect ratio wing, and I'm willing to believe the nod for performance
still goes to the conventional tail.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes"http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org- Hide quoted text -

- Show quoted text -

Bill,

Didnt one of the early flying wings use this for yaw control? small
spoilers at the tip of the wings. im imagining a long wing with a pod
on front and a boom back to just an elevator. sure would look cool

"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

wrote in message
ups.com...
On Jul 6, 8:56 am, "Bill Daniels" bildan@comcast-dot-net wrote:
Just idle fun speculation, of course. Clearly, a conventional rudder
like
the Genesis wouldn't work with a 31 meter span. But, it would take only
a
tiny amount of drag at the wing tip acting through a 15 meter moment arm
to
produce huge yaw moments. I've run this calculation a few times and the
net
drag of tip drag rudders would acutally be less than a conventional
rudder.
A trailing edge elevator would work fine regardless of the span. The
Genesis "T" tail is actually a hinderance.

As for the control moments to control engine thrust and "P" factors, yes,
that is a challenge. A few prople have suggested lowering the thrust
line
so it passes through the CG and aerodynamic center. The rear propeler
could
fold back somewhat like a Carat and be pulled into a tube in the rear
fuselage. Not sure how the landing gear would work with a low thrust
line.

Obviously there would be some weight reduction to the 'non lifting parts'
that would roll through the wing spar calculations allowing a lighter
wing.
Probably not a huge weight reduction but every bit helps the wing bending
moment.

Turning flight might be easier. The short fuselage could be kept aligned
with the local airflow easier than the very long one of the ETA.

Obviously, something like this isn't a 'cut and paste' sort of design.
Each
aspect of the design would break new ground and have to be carefully
thought
through. Each design change would affect everything else.

Bill Daniels

"Eric Greenwell" wrote in message

news:nmkji.6642$wu5.6324@trndny03...



Bill Daniels wrote:
I think this incident may have an influence on future designs. The
Genesis
obtains excellent handling and quite respectable performance without
a
tail boom which forces the question, " Why have one?" The 18 meter
and
larger gliders would obtain even greater relative performance and
damage
resistance since the fuselage size need not increase in porportion to
wing span.

I suspect the increase in wing span might still require a commensurate
increase in rudder/fin and boom length, just to control yaw, even it
wasn't needed for the elevator. Also, flapped gliders have relatively
less
drag from the elevator than aileron-only gliders, so I think they would
have still be better off because the wing could be more easily
optimized
for performance.

I wonder what the ETA would be like with the Genesis fuselage.

A further complication with the ETA is controlling the glider under
power.
I have no idea how it would work out in practice, but I'm guessing any
advantages of the Genesis type design would be lessened by the control
requirements under power. Add in the problems of stabilizing a floppy,
high-aspect ratio wing, and I'm willing to believe the nod for
performance
still goes to the conventional tail.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes"http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation"
atwww.motorglider.org- Hide quoted text -

- Show quoted text -

Bill,

Didnt one of the early flying wings use this for yaw control? small
spoilers at the tip of the wings. im imagining a long wing with a pod
on front and a boom back to just an elevator. sure would look cool

Most flying wings use some sort of wing tip drag rudder. The Genesis uses
"flippers" that move upwards at twice the rate of the ailerons. The B2 uses
split trailing edge drag rudders.

The stabilizer/elevator doesn't need the long boom at all. Placing the
elevators on the inboard wing trailing edge works very well.

Bill Daniels

Bill Daniels wrote:
Just idle fun speculation, of course. Clearly, a conventional rudder like
the Genesis wouldn't work with a 31 meter span. But, it would take only a
tiny amount of drag at the wing tip acting through a 15 meter moment arm to
produce huge yaw moments. I've run this calculation a few times and the net
drag of tip drag rudders would acutally be less than a conventional rudder.
A trailing edge elevator would work fine regardless of the span. The
Genesis "T" tail is actually a hinderance.

Now a portion of the wing is not working at the optimum flap setting. I
think that the drag would be significant. The Genesis optimization
problem is quite different, as is a conventional Standard Class glider
optimization compared to a 15 Meter class glider. Note how different the
wing designs tend to be for Standard vs 15 Meter gliders (generally
lower aspect ratio/larger area for the Standard class).


As for the control moments to control engine thrust and "P" factors, yes,
that is a challenge. A few prople have suggested lowering the thrust line
so it passes through the CG and aerodynamic center. The rear propeler could
fold back somewhat like a Carat and be pulled into a tube in the rear
fuselage. Not sure how the landing gear would work with a low thrust line.

Perhaps using a jet would make the problem much easier; at least, the
thrust could be closer to the center line.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

"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

"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