Akaflieg Karlsruhe AK-X

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