Marske Flying Wings do not stall

[Marske Flying Wings]

I did a modest cross country in the Pioneer IId yesterday but what is most
interesting was that I am exploring all of the flight envelope and yesterday
was stalls. When I pulled the stick all the way back slowly I suddenly found
that my airspeed had fallen to zero where I held it for quite some time and
my sink rate was 100 down. And I have it on video! I did this many times
although there was tendency to turn to the left since we have a left turn in
the glider.

The airspeed system was calibrated recently, both the airspeed instrument
and the installation, however I did not do the calibration for zero
airspeed... so it could be off slightly.

I have posted a picture on the web site showing the airspeed near zero and
will post a video shortly.

http://www.continuo.com/marske/pioneer/marske/marske%20pioneer.htm

This is rather a long address so if this does not work go to our web site
and find "Marske Pioneer IId"

-mat

I have been recording all of this on video to give some credibillity to my
claims.
--
Marske Flying Wings
http://www.continuo.com/marske

[Marske Flying Wings]

No this is where you are quite wrong! There is pleanty of up elevator on the
trailing edge of the main wing.... the air going over the top is separating
due to the high angle of attack and this makes the elevator ineffective, so
the nose lowers slightly and the glider picks up airspeed and it resumes
normal flight.


"spektr" > wrote in message
...
>
>>
> Bravo.
> So you are flying a glider with insufficient up elevator to cause a stall
> equipped
> with an airspeed indicator that doesn't register well on the low end of
the
> spectrum.
> All wings stall when their critical angle of attack is exceeded. In its
> most benign
> form a stall will be recognnized as a slight vertical oscillation without
a
> discernable
> break. If you had more elevator authority, it would get into this flight
> mode. Its inability
> to do so indicates a lack of elevator authority at slow speed.
>
> Your airspeed indicator reading zero means you are flying at a speed less
> than the minimum
> required to move the needle. You are probablu using a run of the mill ASI
> for airplanes.
> Nothing wrong with that, it just means you are slower than the gauge can
> indicate. You
> might consider an ASI for helicopters, they are much more sensitive at the
> lower end
> of the spectrum and will probably give you a better indication of whats
> going on.
> If you want to make your glider even more efficient, replace the ASI with
a
> Mach Meter.
> Then you can get 30 something to one l/d with an indicated airspeed of
ZERO.
>
> OBTW, Its impossible to fly with an airspeed of zero, lift requires air
> movement over the wing
> on any conventional fixed wing airplane. You by definition still have
> airspeed if you are flying.
>
> Scott
>
Scott did you miss the part in my posting where I said this airspeed was
calibrated by itself and then while in the glider at differing airspeeds
from 40 mph to 80 mph. using a GPS method posted on our website. It is also
helicopter airspeed. Now I do think that at about 20 mph the airpspeed goes
to zero... but again I did not test it in the aircraft for this slow a
flight. What did confuse me was the low sink rate... but I could have been
in rising air... and next time I will check my GPS groundspeed. But I have
this on video and will post it for all to see.

I was actually quite surprised myself and do not really know what to think
of it. By the way this aircraft has a 3.6 lbs per sq ft wing loading and I
easily fly at 90 to 100 mph. and I have videos of that too. Again that part
of the spectrum has not been calibrated but it is interesting to see how
well it flies at that speed. I will push for 130 mph in the sping when I
have redone the canopy and fuselage.

-mat

[Bob Kuykendall]

Earlier, Mat Redsell wrote:

> the air going over the top is separating
> due to the high angle of attack...

Sounds like a stalled condition to me.

Bob K.

[Al]

So its under elevatored then.

Al

"Marske Flying Wings" > wrote in message
...
> No this is where you are quite wrong! There is pleanty of up elevator on
the
> trailing edge of the main wing.... the air going over the top is
separating
> due to the high angle of attack and this makes the elevator ineffective,
so
> the nose lowers slightly and the glider picks up airspeed and it resumes
> normal flight.
>
>
> "spektr" > wrote in message
> ...
> >
> >>
> > Bravo.
> > So you are flying a glider with insufficient up elevator to cause a
stall
> > equipped
> > with an airspeed indicator that doesn't register well on the low end of
> the
> > spectrum.
> > All wings stall when their critical angle of attack is exceeded. In its
> > most benign
> > form a stall will be recognnized as a slight vertical oscillation
without
> a
> > discernable
> > break. If you had more elevator authority, it would get into this
flight
> > mode. Its inability
> > to do so indicates a lack of elevator authority at slow speed.
> >
> > Your airspeed indicator reading zero means you are flying at a speed
less
> > than the minimum
> > required to move the needle. You are probablu using a run of the mill
ASI
> > for airplanes.
> > Nothing wrong with that, it just means you are slower than the gauge can
> > indicate. You
> > might consider an ASI for helicopters, they are much more sensitive at
the
> > lower end
> > of the spectrum and will probably give you a better indication of whats
> > going on.
> > If you want to make your glider even more efficient, replace the ASI
with
> a
> > Mach Meter.
> > Then you can get 30 something to one l/d with an indicated airspeed of
> ZERO.
> >
> > OBTW, Its impossible to fly with an airspeed of zero, lift requires air
> > movement over the wing
> > on any conventional fixed wing airplane. You by definition still have
> > airspeed if you are flying.
> >
> > Scott
> >
> Scott did you miss the part in my posting where I said this airspeed was
> calibrated by itself and then while in the glider at differing airspeeds
> from 40 mph to 80 mph. using a GPS method posted on our website. It is
also
> helicopter airspeed. Now I do think that at about 20 mph the airpspeed
goes
> to zero... but again I did not test it in the aircraft for this slow a
> flight. What did confuse me was the low sink rate... but I could have been
> in rising air... and next time I will check my GPS groundspeed. But I have
> this on video and will post it for all to see.
>
> I was actually quite surprised myself and do not really know what to think
> of it. By the way this aircraft has a 3.6 lbs per sq ft wing loading and I
> easily fly at 90 to 100 mph. and I have videos of that too. Again that
part
> of the spectrum has not been calibrated but it is interesting to see how
> well it flies at that speed. I will push for 130 mph in the sping when I
> have redone the canopy and fuselage.
>
> -mat
>
>
>
>
>
>

[Robert Ehrlich]

Marske Flying Wings wrote:
>
> I did a modest cross country in the Pioneer IId yesterday but what is most
> interesting was that I am exploring all of the flight envelope and yesterday
> was stalls. When I pulled the stick all the way back slowly I suddenly found
> that my airspeed had fallen to zero where I held it for quite some time and
> my sink rate was 100 down. And I have it on video! I did this many times
> although there was tendency to turn to the left since we have a left turn in
> the glider.
>
> The airspeed system was calibrated recently, both the airspeed instrument
> and the installation, however I did not do the calibration for zero
> airspeed... so it could be off slightly.
>
> I have posted a picture on the web site showing the airspeed near zero and
> will post a video shortly.
>
> http://www.continuo.com/marske/pioneer/marske/marske%20pioneer.htm
>
> This is rather a long address so if this does not work go to our web site
> and find "Marske Pioneer IId"
>
> -mat
>
> I have been recording all of this on video to give some credibillity to my
> claims.
> --
> Marske Flying Wings
> http://www.continuo.com/marske

A zero speed indication is not surprising in these conditions, and doesn't
mean the speed (or even its horizontal component) is zero, but rather that
the pitot tube used by the ASI for total pressure is no more at the stagnation
point in these conditions and so you don't get the true total pressure. I guess
that the pitot is in the nose and when near stall angle the stagnation point
is well below, with a nice round nose like on the Pioneer IId, the pitot may even
be at a point where the airflow is accelerated at a speed higher than the freestream
speed, so the pressure is lower than the static pressure and the ASI should show
a negative speed if it could. Isn't that the reason for what modern gliders with
a nose pitot have a sharp nose (ASW20, Pegases) and many other ones have a pitot
in the fin?

[spektr]

"BD5ER" > wrote in message
...
> Doesn't this kind of depend on your definition of flight? The Kaspar wing
can
> enter and recover from a controlled vertical decent. In this case the
forward
> airspeed is zero but you are still in the air and in control.......and if
that
> air is rising fast enough....
>

There is no such thing as "forward airspeed". Just Airspeed.
The speed of the air over the wing is completely independent
of ground reference points. If you want to use a ground
reference, use GROUND SPEED. Airspeed and Groundspeed
are easily confused when you try to describe things so don't take it so
hard. To use your illustration, push the nose down 100 degrees from
vertical, you are now slightly inverted and traveling backwards
over the ground. Do you now have NEGATIVE AIRSPEED?
Don't think so.............

Scott

[spektr]

"Marske Flying Wings" > wrote in message
...
> I guess it depends on your definition of a stall. Most stalls end with a
> marked nose down attitude but not so with the Marske Pioneer, just a
little
> forward stick and you have it flying again without any nose down attitude
> while it gets up to flying speed..
>
> -mat
>


Mat.
What you are describing is the high sink rate/high
drag attitude before a stall break occurs.
You are saying that the recovery requires forward stick
to exit the high sink mode of flight. Fair enough.
What that indicates is a lack of elevator authority.
You are unable to put enough pitch command into
the airframe to stall it. Your premise that most stalls
end with a marked nose down attitude is probably
acceptable for straight line flight, not circling or in
attitudes with more than 1g on the airplane. Roll 45
degrees pull hard, bleed energy and you can generate a snap
roll spin entry.
Scott.

[Bill Daniels]

"Bob Kuykendall" > wrote in message
...
> Earlier, Mat Redsell wrote:
>
> > the air going over the top is separating
> > due to the high angle of attack...
>
> Sounds like a stalled condition to me.
>
> Bob K.
>
Again, not quite. Mat is describing an incipient stall, not a full stall.

The PII is under-elevatored with respect to stalling the aircraft but not
with respect to achieving CLmax. The Marske PII elevator authority
limitation is directly related to the incipient stalling of the wing. At
airspeeds above stall, the elevator authority is as large or larger than
conventional gliders. But as the incipient stall begins, the elevator
authority is sharply limited. (Another way to say this is that there is a
large non-linearity in elevator authority that sharply reduces elevator
effectiveness as the incipient stall begins.) This is not a linear function
of AOA or airspeed. As far as I know, this behavior is unique to plank-type
flying wings - particularly those with the elevators on the inboard trailing
edge of the wing such as the Marske planform.

On the other hand, with a conventional tailed aircraft, there is no link
between the elevator authority and the stalling behavior of the wing. In
the case of a conventional glider with a horizontal tail located some
distance aft of the wing, the wing may be fully stalled or fully flying, or
anywhere in between, with no effect on the elevator authority. Depending on
the elevator area, up angle limit, airspeed and CG location, the elevator
may be able to bring the wing to stall or beyond without the wing stall
imposing any limits on the up elevator authority at all. The designer may
choose to impose limits on up elevator authority to achieve benign stalling
behavior - this is not the case with the Marske planform.

As to Mat's report of near zero airspeeds, there are certainly large ASI
errors involved and the true airspeed is almost certainly not zero. To get
a true reading, Mat would need a nose boom with a gimballing pitot/static
probe and a sensitive calibrated ASI.

However, there are many reports of special conditions where a spanwise
vortex forms above the wing at high AOA preserving a large amount of lift.
One prototype of the Velocity canard pusher encountered this phenomenon with
the forward wing which resulted in the aircraft settling in a flat attitude
at low sink rates. The aircraft was not recoverable from this condition and
the test pilot elected to ride it into Tampa Bay at <200FPM sink and lived
to tell the tale. The Kasper Wing apparently can do this as well but is
recoverable.

It would be interesting to see a video of yarn tufts on the upper wing
surface to help visualize the flow with near-zero indicated airspeed.

Bill Daniels

[Kirk Stant]

"Marske Flying Wings" > wrote in message

> When I pulled the stick all the way back slowly I suddenly found
> that my airspeed had fallen to zero where I held it for quite some time and
> my sink rate was 100 down.

Must be that antigravity effect that flying wings are famous for...or
maybe you had an inadvertent deployment of a recovery parachute.

Seriously, Matt, what you probably saw is the same thing most gliders
do when put into a severe slip - the pitot gets masked or moves into
turbulent airflow and no longer indicates your actual airspeed. Ditto
with the rate of sink, perhaps (static port location?). Where is your
pitot located?

Do you have a GPS logger trace of this event? That should show what
your actual groundspeed (and sink rate, with the right software) was.
Repeat the exercise upwind and downwind, then tell us what really
happened.

Meanwhile, enjoy your wing!

Kirk
Happy with the nice, long, beautiful tail of my LS6

[Marske Flying Wings]

We have a pitot tube.. 1/4 " slightly protruding out from the front of the
nose inside a 2 " vent tube in the normal nose location. As I said before, I
will check my GPS ground speed on the next attempt.

I fly all kinds of gliders so I do know a slip well... but this is no slip.
Watch for that video!

I started at 40 mph and slowly went from 35 to 30 to 25 then 20 and then
zero. The video will show all of this on the instrument panel.....and I did
this more than once. I doubt that I actually got to zero..... but the
forward speed was definitely down about 20 or lower. I have boom mounted
turbine and will attach that on one of next flights.

-mat

"Kirk Stant" > wrote in message
om...
> "Marske Flying Wings" > wrote in message
>
> > When I pulled the stick all the way back slowly I suddenly found
> > that my airspeed had fallen to zero where I held it for quite some time
and
> > my sink rate was 100 down.
>
> Must be that antigravity effect that flying wings are famous for...or
> maybe you had an inadvertent deployment of a recovery parachute.
>
> Seriously, Matt, what you probably saw is the same thing most gliders
> do when put into a severe slip - the pitot gets masked or moves into
> turbulent airflow and no longer indicates your actual airspeed. Ditto
> with the rate of sink, perhaps (static port location?). Where is your
> pitot located?
>
> Do you have a GPS logger trace of this event? That should show what
> your actual groundspeed (and sink rate, with the right software) was.
> Repeat the exercise upwind and downwind, then tell us what really
> happened.
>
> Meanwhile, enjoy your wing!
>
> Kirk
> Happy with the nice, long, beautiful tail of my LS6

[Keith W]

> There is no such thing as "forward airspeed". Just Airspeed.
> The speed of the air over the wing is completely independent
> of ground reference points. If you want to use a ground
> reference, use GROUND SPEED. Airspeed and Groundspeed
> are easily confused when you try to describe things so don't take it so
> hard. To use your illustration, push the nose down 100 degrees from
> vertical, you are now slightly inverted and traveling backwards
> over the ground. Do you now have NEGATIVE AIRSPEED?
> Don't think so.............
>
> Scott
>
But what happens when you cock up a chandelle and don't get the nose down
before you loose forward airspeed? Seems like negative (or backwards)
airspeed to me! 8-)

Keith

[Marske Flying Wings]

Well I have just posted the video, while I did take my time getting the aft
limit of the contorl stick it was not quite at 1 knot per second.... so I
will keep that in mind for the next session.Check out the video on the
Marske Pioneer IId page.!

-thanks
-mat

"dhb" > wrote in message
thlink.net...
> One of the several FAA definitions that are involved in determining stall
> speeds is when the aft stick limit is reached.
>
> Another is the FIRST time the nose starts down as you are bringing the
> stick aft.
>
> Make sure that you do this test at the official 1 knot per second entry
rate.
>
>
>
>
>
> In article >, "Marske Flying
Wings"
> > wrote:
> >I did a modest cross country in the Pioneer IId yesterday but what is
most
> >interesting was that I am exploring all of the flight envelope and
yesterday
> >was stalls. When I pulled the stick all the way back slowly I suddenly
found
> >that my airspeed had fallen to zero where I held it for quite some time
and
> >my sink rate was 100 down. And I have it on video! I did this many times
> >although there was tendency to turn to the left since we have a left turn
in
> >the glider.
> >
> >The airspeed system was calibrated recently, both the airspeed instrument
> >and the installation, however I did not do the calibration for zero
> >airspeed... so it could be off slightly.
> >
> >I have posted a picture on the web site showing the airspeed near zero
and
> >will post a video shortly.
> >
> >http://www.continuo.com/marske/pioneer/marske/marske%20pioneer.htm
> >
> >This is rather a long address so if this does not work go to our web site
> >and find "Marske Pioneer IId"
> >
> >-mat
> >
> >I have been recording all of this on video to give some credibillity to
my
> >claims.

[Lennie the Lurker]

"spektr" > wrote in message >...
>
> Bravo.
> So you are flying a glider with insufficient up elevator to cause a stall
> equipped
> with an airspeed indicator that doesn't register well on the low end of the
> spectrum.
> All wings stall when their critical angle of attack is exceeded.

All wings stall when their angle of attack is beyond the limits. But
don't put the tendency for flying wings to not stall viciously as an
attribute of insufficient elevator. If the elevator had enough
authority to hold the wing past the critical angle, nobody would have
the touch fine enough to fly it. Contrasted to the brute force system
of "conventional" designs, it takes very little to control the
attitude of the flying wing types.

A little time spent beyond the fiberglass and foam model kits might
have allowed more people to experiment with things that are
"interesting". The "Scimitar" design is a good example but those not
interested in having to actually build never found out.

[BD5ER]

>There is no such thing as "forward airspeed".

All depends on where your point of referance is if the vector is positive or
negative. All of the planes I have flown had the pitot somewhere in the front
and I tend to have that stuck in my mind as the referance point. Substitute
"ground speed" solar speed or what ever speed you like but da ting duz wat is
duz <G>

[spektr]

"Bill Daniels" > wrote in message
...

> The Marske planform does eliminate the stall/spin as a likely source of
> accidents and, apparently, without a performance penalty. In exchange for
> this, it introduces another area where the pilot determined to find a way
to
> crash can do so.
>

Bill.
Very good points made.
But the Marske planform can and has entered spins.
It may not be a likely outcome of a stall , but if you go
to the NTSB website, look for the only Monarch crash.
Jim talked this accident thru with me and they still aren't sure
how the pilot did it. The pilot stalled in the pattern, spun in
impacting the ground. I don't hold this against the aircraft,
in fact I've had talked on the phone to Mat and Jim on several
occasions about their gliders. I do like what I see and hear
and I'm probably going to build a Monarch

But back to the point............

It has insufficient elevator at low speeds to stall the aircraft.
it has a high sink rate/drag envelope when slow that is different
from most other gliders. You can train your way around these things
but the premise of the discussion , non-stallability, is incorrect.

Weve beaten the 0 airspeed thing to death.

Scott

[Marske Flying Wings]

I think it is important to understand that we did not build this Monarch F
and did not know where the CG was, what wing tips he had on it are not clear
either. We viewed the video of the flight and a wing did drop but in less
than a rotation the wing was flyiing again... but the pilot entered another.
My feeling is that the pilot froze up.... as he said himself and may have
pulled the stick all the way back and crossed the controls. I do feel he had
a very far froward CG given his weight. If the CG is far forward the glider
can be made to have a sharp break in the stall.
At any rate we could not make this happen on the Current Monarch G's. I flew
a Monarch F for a couple of seasons and it was not able to spin or stall..

When we were experimenting with the CG on the Pioneer IId we could get it
to break on a stall if the CG was too far forward.

thanks for your input.

-mat


"spektr" > wrote in message
...
>
> "Bill Daniels" > wrote in message
> ...
>
> > The Marske planform does eliminate the stall/spin as a likely source of
> > accidents and, apparently, without a performance penalty. In exchange
for
> > this, it introduces another area where the pilot determined to find a
way
> to
> > crash can do so.
> >
>
> Bill.
> Very good points made.
> But the Marske planform can and has entered spins.
> It may not be a likely outcome of a stall , but if you go
> to the NTSB website, look for the only Monarch crash.
> Jim talked this accident thru with me and they still aren't sure
> how the pilot did it. The pilot stalled in the pattern, spun in
> impacting the ground. I don't hold this against the aircraft,
> in fact I've had talked on the phone to Mat and Jim on several
> occasions about their gliders. I do like what I see and hear
> and I'm probably going to build a Monarch
>
> But back to the point............
>
> It has insufficient elevator at low speeds to stall the aircraft.
> it has a high sink rate/drag envelope when slow that is different
> from most other gliders. You can train your way around these things
> but the premise of the discussion , non-stallability, is incorrect.
>
> Weve beaten the 0 airspeed thing to death.
>
> Scott
>
>
>

[Ian Johnston]

On Thu, 31 Jul 2003 17:27:46 UTC, "Marske Flying Wings"
> wrote:

: No this is where you are quite wrong! There is pleanty of up elevator on the
: trailing edge of the main wing.... the air going over the top is separating
: due to the high angle of attack and this makes the elevator ineffective, so
: the nose lowers slightly and the glider picks up airspeed and it resumes
: normal flight.

Which is, effectively, exactly what he said...

: "spektr" > wrote in message
: ...

: > So you are flying a glider with insufficient up elevator to cause a stall

Ian

[Ian Johnston]

On Fri, 1 Aug 2003 02:00:17 UTC, "Bill Daniels"
> wrote:

: The Marske planform does eliminate the stall/spin as a likely source of
: accidents

From what was posted here, it stalls fine but as a mushing stall
(which is exactly what I get in a K8). Just as a matter of interest,
what happens in a Marske if you stall it and then kick in a bootful of
rudder? Or stall it in a thermalling turn? Does failure to drop the
nose at stall really mean it can't spin?

Ian

--

[Bill Daniels]

"Ian Johnston" > wrote in message
news:cCUlhtvFIYkV-pn2-EdKXeK7dL0Wj@localhost...
> On Fri, 1 Aug 2003 02:00:17 UTC, "Bill Daniels"
> > wrote:
>
> : The Marske planform does eliminate the stall/spin as a likely source of
> : accidents
>
> From what was posted here, it stalls fine but as a mushing stall
> (which is exactly what I get in a K8). Just as a matter of interest,
> what happens in a Marske if you stall it and then kick in a bootful of
> rudder? Or stall it in a thermalling turn? Does failure to drop the
> nose at stall really mean it can't spin?
>
> Ian
>
Ian, Flying both the Pioneer 1A and the Pioneer II, I have held full rudder
through a series of stall attempts and all I got was a mushing turn. I was
never able to get anything even remotely resembling a spin departure. In
several tests I made extreme attempts to get a departure without success.
The slow flight behavior is benign in the extreme even with the CG aft of
the rear limit.

Now, lets talk about stalls. If you get a nose drop, that doesn't
necessarily mean a stall has occurred. To my way of thinking, a stall
require a substantial disruption of airflow over the upper surface of the
wing resulting in loss of lift and a departure from controlled flight.

My experience with Marske gliders is the same as other pilots in that the
ailerons remain fully effective and the elevator control retains a solid
feel. In short, the glider never departs controlled flight. What you do get
is a sharp loss of up elevator authority as the AOA exceeds a certain value
and the nose bobs down a bit. I really don't feel comfortable calling that
a stall since the airflow over the majority (probably the forward 60% of the
chord) of the wing remained attached.

Even the description, "mushing stall" seems inappropriate. The glider
doesn't even sink rapidly at minimum airspeed with the stick full back - it
just glides slowly along with all controls fully effective.

This doesn't mean you can't crash the glider - it just means you have to
work a lot harder to do it.

Bill Daniels

[Ian Johnston]

On Sat, 2 Aug 2003 12:49:49 UTC, "Bill Daniels"
> wrote:

: My experience with Marske gliders is the same as other pilots in that the
: ailerons remain fully effective and the elevator control retains a solid
: feel.

Sounds just like a mushing stall in a Ka8!

: Even the description, "mushing stall" seems inappropriate. The glider
: doesn't even sink rapidly at minimum airspeed with the stick full back - it
: just glides slowly along with all controls fully effective.

Sounds just like a Ka8 with an elevator stop. Primary gliders used to
have these ...

Ian


--

[Eric Greenwell]

In article <cCUlhtvFIYkV-pn2-389QQ1tlWSrk@localhost>,
says...
> On Sat, 2 Aug 2003 12:49:49 UTC, "Bill Daniels"
> > wrote:
>
> : My experience with Marske gliders is the same as other pilots in that the
> : ailerons remain fully effective and the elevator control retains a solid
> : feel.
>
> Sounds just like a mushing stall in a Ka8!
>
> : Even the description, "mushing stall" seems inappropriate. The glider
> : doesn't even sink rapidly at minimum airspeed with the stick full back - it
> : just glides slowly along with all controls fully effective.
>
> Sounds just like a Ka8 with an elevator stop. Primary gliders used to
> have these ...

Can the Ka8 with the elevator stop be flown in a 40 degree banked turn
in a mushing stall? Or, asking the question another way: what is the
steepest turn the Ka8 can be flown in and still achieve a mushing
stall?

If I understand the situation correctly, the flying wing will still be
able to achieve the "mushing" condition even in steeply banked turns,
while a conventionally tailed aircraft, like the Ka8, will only be
able to do this in shallow turns (say, 20 degrees or less). This
happens because the mechanism for limiting the AOA in straight flight
is different for each glider:

Flying wing: when near stall, airflow separation at the trailing edge
limits the up elevator effect.

Tailed glider: elevator travel is mechanically limited.
--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly

Eric Greenwell
Richland, WA (USA)