Akaflieg Karlsruhe AK-X

On Tue, 12 Dec 2017 03:30:19 +0000, Michael Opitz
wrote:


Thank you very much for the insights. If my father were still alive
today, he would be wanting to follow the progress very closely. The
aerodynamic genius of using the wing sweep to emulate canard
characteristics as opposed to using the sweep for high speed flight
is extremely intriguing. Being able to use current modern airfoils
while reducing drag considerably, should result in very noticeable
performance increases. Also, the advent of newer construction
materials and methods which enable the builders to achieve the
stiffness that is required to overcome other previous wing's
aeroelastic issues cannot be overstated.

Please post any progress updates here whenever you may hear of
them in the future....

I promise.
I happen to be at the Akaflieg Karlsruhe workshop two times per year
so with a little luck I can provide you with some updates if the
Akaflieg guys allow that.


But since we are talking:
Has your father ever talked about (or even flown) the Horten VI (the
24m glider)? I was always amazed that such a thing could be built in
the pre-carbon fibre aera.

There are a couple of reports about the IV, but I couldn't find any
halfways detailed source about the VI.

And, second question:
Do you know if the Horton guys aver considered winglets instead of the
drag ailerons?

Cheers
Andreas

At 00:34 13 December 2017, Andreas Maurer wrote:
On Tue, 12 Dec 2017 03:30:19 +0000, Michael Opitz
wrote:


Thank you very much for the insights. If my father were still
alive
today, he would be wanting to follow the progress very closely.
The
aerodynamic genius of using the wing sweep to emulate canard
characteristics as opposed to using the sweep for high speed
flight
is extremely intriguing. Being able to use current modern airfoils
while reducing drag considerably, should result in very noticeable
performance increases. Also, the advent of newer construction
materials and methods which enable the builders to achieve the
stiffness that is required to overcome other previous wing's
aeroelastic issues cannot be overstated.

Please post any progress updates here whenever you may hear
of
them in the future....

I promise.
I happen to be at the Akaflieg Karlsruhe workshop two times per
year
so with a little luck I can provide you with some updates if the
Akaflieg guys allow that.


But since we are talking:
Has your father ever talked about (or even flown) the Horten VI
(the
24m glider)? I was always amazed that such a thing could be built
in
the pre-carbon fibre aera.



Martin Gregorie provided a pretty good link for a brief Horten
history:

https://scalesoaring.co.uk/VINTAGE/D.../Horten%20IV/H
orten_IVb.html

From that article:

"As Heinz Scheidhauer was the most experienced and long serving
Horten pilot, it is also strange that the test flying of the H IVb should
be passed to Strebel at such an early stage.

Scheidhauer had flown most of the Horten types and despite some
peculiarities, their handling had been generally benign as they were
highly stall and spin resistant. Although the H IVa had been liable to
flutter, it had proved possible to damp it by simultaneous use of the
drag rudders. None the less, he had refused to fly an HIII to explore
its handling at extreme rear centre of gravity positions. On 24 May
1944 he made the maiden flight of the ultra high aspect ratio H VI,
discovering that not only was it subject to flutter at both high and
low speeds but that the entire wing was far too flexible and fragile
for even an expert pilot.

If Zubert’s log book entry is correct, the pilot of the H IVb on 11
August was almost certainly Scheidhauer and this may also have
been its maiden flight – long before the H XIIIa.

Unfortunately just ten weeks after test flying the H VI, Scheidhauer
discovered that the H IVb suffered from truly appalling handling
characteristics and would abruptly drop a wing and attempt to spin
at speeds as high as 77km/h, yet above 110 km/h the wings would
flutter. Later, also he refused to fly the H XIIIa which Strebel tested
from the outset. It seems that Scheidhauer was losing faith in
Reimar’s ability as a designer."


Scheidhauer was a student of Dad's from the first military glider
pilot training class at the DFS in ~1937 where Dad was one of the
three original instructors. Dad also later got him a flight in a Me
163, even though he was from the Horten camp. By 1944 when
Scheidhauer first flew the Ho VI, Dad was pretty deep into getting
operational Me 163 units up and running. His glider logbook shows
one or two Ho III entries earlier, but no Ho VI. He never really
talked about the Ho VI at all. I doubt it flew much considering the
info from the above story.


There are a couple of reports about the IV, but I couldn't find any
halfways detailed source about the VI.

And, second question:
Do you know if the Horton guys aver considered winglets instead
of the
drag ailerons?


I don't know if they considered winglets, and I can't remember what
the aircraft they designed after the war in Argentina looked like.
The person to ask is Peter Selinger. He was also a friend of
Scheidhauer's and received all of Scheidhauer's personal logs, etc
when he passed away. Peter also wrote a book on the Hortens, but
unfortunately, I don't have a copy of it.

"Nurflügel", by Peter F. Selinger and Dr. Reimar Horten
ISBN-103900310092
ISBN-139783900310097

I do have Peter's contact info in case you want it though. We have
been in fairly regular contact with each other since 1985.

RO

Michael,
I am interested in the crosswind landing characteristics of flying wings, do you have any information on the discussed ships? The Genesis-2 has no problem landing in a crosswind, but as the forward speed slows to equal the crosswind speed, the ship turns into the wind and opposite rudder does nothing! After years of stopping on the runway, I deliberately started carrying an extra 10 knots of speed into the desired stopping area, then jump on the good hydraulic brake to stop the ship where desired.
JJ

On Wednesday, December 13, 2017 at 7:42:38 AM UTC-8, wrote:
Michael,
I am interested in the crosswind landing characteristics of flying wings, do you have any information on the discussed ships? The Genesis-2 has no problem landing in a crosswind, but as the forward speed slows to equal the crosswind speed, the ship turns into the wind and opposite rudder does nothing! After years of stopping on the runway, I deliberately started carrying an extra 10 knots of speed into the desired stopping area, then jump on the good hydraulic brake to stop the ship where desired.
JJ

A steerable nose wheel would solve this problem. On my ASH26 Mi, I'd sooner give up the engine than the steerable tailwheel.

On Wednesday, December 13, 2017 at 12:06:56 PM UTC-5, jfitch wrote:
On Wednesday, December 13, 2017 at 7:42:38 AM UTC-8, wrote:
Michael,
I am interested in the crosswind landing characteristics of flying wings, do you have any information on the discussed ships? The Genesis-2 has no problem landing in a crosswind, but as the forward speed slows to equal the crosswind speed, the ship turns into the wind and opposite rudder does nothing! After years of stopping on the runway, I deliberately started carrying an extra 10 knots of speed into the desired stopping area, then jump on the good hydraulic brake to stop the ship where desired.
JJ

A steerable nose wheel would solve this problem. On my ASH26 Mi, I'd sooner give up the engine than the steerable tailwheel.

A steerable nose wheel would only work well, if the main wheel location is moved further back.
RS

On Wed, 13 Dec 2017 05:10:38 +0000, Michael Opitz
wrote:

Martin Gregorie provided a pretty good link for a brief Horten
history:

https://scalesoaring.co.uk/VINTAGE/D.../Horten%20IV/H
orten_IVb.html


Thank you very much - extremely interesting lecture that I didn't know
yet.

Scheidhauer had flown most of the Horten types and despite some
peculiarities, their handling had been generally benign as they were
highly stall and spin resistant. Although the H IVa had been liable to
flutter, it had proved possible to damp it by simultaneous use of the
drag rudders. None the less, he had refused to fly an HIII to explore
its handling at extreme rear centre of gravity positions. On 24 May
1944 he made the maiden flight of the ultra high aspect ratio H VI,
discovering that not only was it subject to flutter at both high and
low speeds but that the entire wing was far too flexible and fragile
for even an expert pilot.

Sounds.... interesting and exciting.


Scheidhauer was a student of Dad's from the first military glider
pilot training class at the DFS in ~1937 where Dad was one of the
three original instructors. Dad also later got him a flight in a Me
163, even though he was from the Horten camp. By 1944 when
Scheidhauer first flew the Ho VI, Dad was pretty deep into getting
operational Me 163 units up and running. His glider logbook shows
one or two Ho III entries earlier, but no Ho VI. He never really
talked about the Ho VI at all. I doubt it flew much considering the
info from the above story.

This would be the next interesting topic in RAS: "What the test pilot
thought about the Me-163 as a glider"....

I don't know if they considered winglets, and I can't remember what
the aircraft they designed after the war in Argentina looked like.
The person to ask is Peter Selinger. He was also a friend of
Scheidhauer's and received all of Scheidhauer's personal logs, etc
when he passed away. Peter also wrote a book on the Hortens, but
unfortunately, I don't have a copy of it.

"Nurflügel", by Peter F. Selinger and Dr. Reimar Horten
ISBN-103900310092
ISBN-139783900310097

I do have Peter's contact info in case you want it though. We have
been in fairly regular contact with each other since 1985.


Thank you very mich again - I'm aware of this book, but to be honest:
I was always a little fascinated by the Horten gliders, but not enough
to buy the book since I always thought their designs were some kind of
one-trick-pony.

The book is available on Amazon Germany - just tell me if I should get
you a copy (how's your German?).


Cheers
Andreas

On Wed, 13 Dec 2017 22:21:43 +0100, Andreas Maurer wrote:

If you're interested in the history of soaring and especially in fins
detail of particular gliders its well worth bookmarking the Scale Soaring
website:

https://scalesoaring.co.uk

Just don't be put off by its name! The in-depth documentation and photos
of the gliders it does cover is excellent, e.g the Fafnir. However, its
overall coverage isn't a patch on Martin Simon's "Sailplanes" three
volume series: you'll definitely want them as well. The Scale Glider
crowd rate them highly for his three-view drawings.


--
Martin | martin at
Gregorie | gregorie
| dot org

On Wed, 13 Dec 2017 21:46:06 +0000 (UTC), Kiwi User
wrote:

On Wed, 13 Dec 2017 22:21:43 +0100, Andreas Maurer wrote:

If you're interested in the history of soaring and especially in fins
detail of particular gliders its well worth bookmarking the Scale Soaring
website:

https://scalesoaring.co.uk

Just don't be put off by its name! The in-depth documentation and photos
of the gliders it does cover is excellent, e.g the Fafnir. However, its
overall coverage isn't a patch on Martin Simon's "Sailplanes" three
volume series: you'll definitely want them as well. The Scale Glider
crowd rate them highly for his three-view drawings.

Well Martin,

guess what's been robbing my time for the last couple of hours.......


Brilliant website!

Cheers
Andreas

At 21:21 13 December 2017, Andreas Maurer wrote:
On Wed, 13 Dec 2017 05:10:38 +0000, Michael Opitz
wrote:

Scheidhauer was a student of Dad's from the first military glider
pilot training class at the DFS in ~1937 where Dad was one of
the three original instructors. Dad also later got him a flight in a Me
163, even though he was from the Horten camp. By 1944 when
Scheidhauer first flew the Ho VI, Dad was pretty deep into getting
operational Me 163 units up and running. His glider logbook shows
one or two Ho III entries earlier, but no Ho VI. He never really
talked about the Ho VI at all. I doubt it flew much considering the
info from the above story.

This would be the next interesting topic in RAS: "What the test
pilot thought about the Me-163 as a glider"....


The Me 163 had an L/D of ~17, but the speeds were too high for
any kind of thermal flight, especially for the heavy weaponized
Me 163b version. Between the good L/D and ground effect, it was
hard to get onto the ground in a reasonable distance until Dr
Lippisch had Josef Hubert design under wing dive brakes for extra
drag. Hubert also came up with the wing slots in front of the
elevons to basically stop the tips from stalling at high AOA.

Now, Dad did thermal a fully loaded (10 people) DFS 230 for
up to an hour, and I heard that some of the passengers may have
gotten a little airsick...

Peter also wrote a book on the Hortens, but unfortunately, I don't
have a copy of it.

"Nurflügel", by Peter F. Selinger and Dr. Reimar Horten
ISBN-103900310092
ISBN-139783900310097


Thank you very much again - I'm aware of this book, but to be
honest:
I was always a little fascinated by the Horten gliders, but not enough
to buy the book since I always thought their designs were some kind
of one-trick-pony.

The book is available on Amazon Germany - just tell me if I should
get you a copy (how's your German?).

Right after I made that post, I found and bought a copy from an
American seller. Danke für's Angebot. Auf Deutsch geht's mir
auch noch recht gut.......

Gruß,

RO

At 05:10 13 December 2017, Michael Opitz wrote:
At 00:34 13 December 2017, Andreas Maurer wrote:

And, second question:
Do you know if the Horton guys ever considered winglets instead
of the drag ailerons?


Andreas,

I just got my copy of the book. The only Horten design which I
found using winglets (although they were ~2-3 meters inboard of
the tips) was on a 4 engine transport, the Ae. 38. The rudders only
moved in the outboard direction, and were controlled by
aerodynamic servo tabs. It only flew once due to being forced
(by nationalistic pride) to use engines that had only 40% of the
power that the aircraft was designed for. It had 30 cubic meters of
storage space. The Ae. 38 was conceived of in 1950 in Argentina.
It eventually flew there in 1960 and was then scrapped.

JJ,

Sorry I didn't answer about your crosswind question earlier. I'm
afraid that I don't know the answer to it though. Unless I find
something about it in the book, anything I would say at this point
would only be speculation except that I don't remember Dad
addressing crosswind landings in the Ho IV. The Me 163 had a
rudder like the Genesis and a much higher approach speed, so it
handled crosswinds like most other aircraft, except when it had
been flown so fast that the transonic flutter had caused the
rudder to disintegrate so badly that only the front spar/hinge
was left. Dad found that result on approach as he tried to slip it
with no result after one particularly high speed flight...

RO