When the newest American
super-bomber, the Northrop B-2, was revealed to the public at
Palmdale, California on November22, 1988, many aviation history
enthusiasts must have noted that the configuration selected by the
aircraft’s designers, namely that of the “flying wing,” had been
resurrected from the dead, as it were. Although present day
experience has shown that the all-wing configuration is the best
one for avoiding detection by enemy radar (aided by the latest
technology in materials, electronics and computers), the same
configuration has been in practical use since about 1930. The
first jet. powered all-wing aircraft flew in Germany on February
2, 1945, and at the time was also virtually undetectable by radar,
partly on account of its mixed construction (wooden wings). In the
United States, John Knudsen Northrop had been working on all-wing
aircraft since the end of the 1920s. His first aircraft of this
configuration (although it did employ two small vertical tail fins
on thin tail booms) was the “Flying Wing,” which flew in 1929.
Because of poor economic conditions during the 1930s, Northrop’s
twin-engined all-wing N1M did not appear until 1940, and the N9M
until 1942.
Individual projects were undertaken in various
countries, but in the Soviet Union there were numerous attempts,
some of them very promising, to learn the secrets of the all-wing
aircraft. The most successful Soviet designer was Boris Ivanovich
Chernanovski, who developed a series of projects from 1921 to
1940.
In Germany, the Horten brothers, Reimar and Walter, had in
mind a pure all-wing aircraft with no vertical control surfaces of
any kind. Inspired by the Stork and Delta-type tailless aircraft
of Alexander Lippisch, they began their work at the end of the
1920s. Successful flight tests of their first tailless glider were
carried out at Bonn-Hangelar airfield in July 1933. By 1934 they
were working at Germany’s “Gliding Mecca,” the Wasserkuppe. The
all-wing concept had achieved its first practical success.
Although development of the all-wing aircraft began at about the
same time in Germany, the Soviet Union and America, there was no
collaboration whatsoever between designers. In spite of this,
design teams in these widely- separated parts of the world were
convinced that the all-wing aircraft was the best configuration
and pursued the idea with much idealism.
It is no wonder,
therefore, that the concept has been revived in the present day.
The Northrop “Flying Wings” and the twin-engined Horten H V, H VII
and H IX aircraft can in a way be considered the forerunners of
the B-2. The H V was a pure research aircraft equipped with two
counter-rotating pusher propellers. The H IX was designed as a
twin-engined, turbojet fighter-bomber, and the H VII, also with
two pusher propellers, was intended to serve as a trainer for jet
aircraft.
Horten Va
The H Va was built in 1936/37 in
cooperation ith the Dynamit AG in Troisdorf, near Cologne.
synthetic material (Trolitax) were used in the aircraft’s
construction. Use of this material resulted in a series of
problems, even though the glider HoL’s der TeufeL had previously
been built using this method. Several of the solutions to these
problems were patented by the Dynamit company. The nose of the H V
was covered in clear Cellon, and the two pilots occupied prone
positions. The aircraft was fitted with a tricycle undercarriage
with faired main members (only the nosewheel was retractable), and
the two Hirth HM.60-R engines drove two-bladed pusher propellers
directly (no extension shafts). The propeller manufacturer Peter
Kiimpel produced the propellers from Lignofol (beech wood
impregnated with synthetic resin). The H Va introduced novel
movable wingtip control surfaces.
The aircraft’s only flight took place at Bonn-Hangelar in early
1937. In the aircraft were Walter and Reimar Horten. The extreme
aft location of the engines made the aircraft unstable, and at its
low takeoff speed the aircraft’s controls were unable to overcome
the resulting tail-heaviness at the moment of rotation. The H Va
became air-borne briefly, then crashed, damaging the aircraft
seriously. The injuries sustained by the two men were relatively
minor (Walter Horten knocked out his two upper front teeth).
Following the accident the Dynamit AG collected the remains of the
H Va to carry out tests on the materials used in its construction.
The H Vb was a research aircraft
built at Cologne-Ostheim using conventional construction methods
(wood and steel tube) on instructions from Major Dinort with the
approval of Ernst Udet. As a result of the accident with the H Va,
the movable wingtip controls were dispensed with and the designers
turned to more conventional elevons. The Hirth engines of the
unlucky H Va were used again, but were positioned further forward
and drove their propellers via short extension shafts, resulting
in a more favourable weight distribution. The H Yb’s pilots sat
upright next to each other and were provided with individual
raised canopies. Like the H Va, the H Yb had a fixed tricycle
undercarriage. The aircraft’s first flight took place at Cologne-Ostheim
in autumn 1937 with Walter Horten at the controls. From the
beginning of the war in 1939 until 1941 the aircraft was parked in
the open at Potsdam-Werder airfield, which was not altogether
beneficial for an aircraft built largely of wood.
Ho Vb
Horten Vc, W-Nr. 27
Efforts by the Luftwaffe-Inspektion
3 (Lln 3, or uftwaffe Inspectorate for Fighters, whose Technical
Department Head was Walter Horten) succeeded in convincing
GeneralflugzeugmetsteT Ernst Udet that it was advisab1e to return
the H V to flying status. In August 1941 a special detachment of
Lln 3 was formed in Minden to oversee the reconstruction of the
aircraft by the Peschke Firm. Peschke, a former WW I fighter
pilot, had established a flying school at Hangelar and later an
aircraft repair facility at Minden.
The latter facility repaired
aircraft such as the Fw 44 Stieglitz, He 72 Kadett, Fi 156 Storch
and the RK Schwalbe. Peschke and the Horten brothers knew each
other from Hangelar. In charge of the Lln 3 detachment was
Luftwaffe Leutnant Reimar Horten. His team consisted of three
designing engineers and five other men, including Heinz
Scheidhauer, an experienced all-wing glider specialist. Later the
special detachment was moved to Göttingen and enlarged to thirty
men (soldiers, engineers, craftsmen and so on).
The Horten Vc was
converted from the H V b, which had been badly damaged by the
elements. In Minden the two-seat H Vb became a single-seat
aircraft. The pilot was accommodated in a normal eated position.
The H Va’s Hirth engines were retained, as were its steel tube and
wood construction and fixed undercarriage. As property of the
military, it was finished in standard Luftwaffe camouflage and was
assigned the code PE + HO (PE for Peschke and HO for Horten).
The
H Vc made its first flight on May 26, 1942. Walter Horten later
flew the machine to Göttingen, where LuftwaffenkommafldO IX was
being formed. Flugkapitän Prof. Dr. Josef Stüper, then Director of
the Instituts fur Forschungsflugbetrieb und Flugwesen (Institute
for Flight Research and Aviation) at the Aerodynamischeti
Versuchsanstalt (A VA) Gottingen (Gottingen Aerodynamic Research
Institute), carried out test flights in the H Vc. Late in the
summer of 1943 an incident occurred involving the H Vc. Stüper
took off from the centre of the airfield with the aircraft’s flaps
in the down position.
The aircraft’s under-carriage struck the
roof of a hangar and the H Vc crashed. Stüper escaped without
serious injury, but the aircraft was badly damaged. It was
subsequently stored at Göttingen in anticipation of restoration
following the end of the war. Events were to prove differently,
however, as all of the aircraft held there were assembled at
the edge of the airfield and burned following Germany’s surrender.
A projected glider tug based on the H Vc was not built.
Ho Vc
Horten VII, W-Nr. 29
Construction of the H VII took
place at the Gottingen Bureau. The aircraft’s wings, which were of
wooden construction, were built by the Lln 3 workshop, while the
centre section, which was of welded tube steel construction with
Dural skinning, was manufactured by the Peschke Firm in Minden.
The aircraft made its first flight in May 1943 with Heinz
Scheidhauer and Walter Horten on board. The aircraft had
originally been conceived as a flying test-bed for the
Argus-Schmidt pulse- jet engine after the H V had proved
unsuitable for the role. When this plan was abandoned it was
proposed as a fighter training aircraft.
The H VII was powered by
two Argus AS-b-C engines driving two-bladed constant-speed
propellers via extension shafts. The aircraft featured a fully
retractable twin nosewheel under-carriage. So-called “wingtip
rudders” were used in place of a conventional rudder. The aircraft
was assigned the RLM-Number 8-226. The aircraft’s pilots were
Heinz Scheidhauer, Erwin Ziller and Walter Horten. In autumn
1944 Oberst Knemeyer demonstrated the H VII to Hermann Goring at
Oranienburg, after the Reichsmarschall had expressed a desire to
see a Horten aircraft in action. Knemeyer was the RLM flight-test
chief and was favourably disposed toward the aircraft developed by
the Horten brothers. Goring, a former WW I fighter pilot, had not
participated in the later gliding boom and was unfamiliar with the
aircraft which emerged from the program.
He wanted to see the
aircraft fly on one engine, which Heinz Scheidhauer did without
any hesitation. The Reichsmarschall was impressed; the Peschke
Firm received an order for twenty examples. Construction of the H
VII V2 began in 1944, but the aircraft had not been completed when
the war ended. The V3, which was to see the “wingtip rudders”
replaced by spoilers above and below the wings, as on the H IX,
progressed no farther than the manufacturing of various
components. In February 1945 Heinz Scheidhauer flew the H VII to
Gottingen. Hydraulic failure prevented him from extending the
aircraft’s undercarriage, and he was forced to make a belly
landing. The resulting damage had not been repaired when, on April
7, 1945, US troops occupied the airfield. The aircraft presumably
suffered the same fate as the H V and was burned.
Ho V11 under final construction
Horten H IX, Werk-Nr.39, 1 944/45
The H IX V2 was a test machine powered by two Jumo
004 turbojets and was assigned the RLM number 8-229. It was the
world’s first turbojet-powered all-wing aircraft. The V2 had a
fully retractable undercarriage and was unarmed. The pilot was
accommodated in a conventional seated position.
The Ho IX V2 under construction in a 3
car garage
Serious difficulties and delays in
construction arose when the planned BMW 003 engines had to be
replaced by more powerful Jumo 004s. The diameter of the Junkers
engine was greater than that of the BMW product, requiring
redesign of the engine bays. Like its predecessors, the aircraft
was of mixed construction. The V2’s undercarriage consisted of the
tailwheel from a wrecked He 177 bomber, which was used as
nose-wheel, and the main undercarriage from a Bf 109 fighter.
The
first test flight was made from Oranienburg on February 2, 1945,
with Leutnant Erwin Ziller at the controls, and lasted about 30
minutes. The Horten brothers had known Ziller from the
competitions at the Wasserkuppe. Ziller had familiarized himself
with all-wing aircraft in December 1944 and January 1945, making
several flights in the Horten H IX Vi glider (an He 111 served as
glider tug) and the twin-engined Horten H VII at Oranienburg.
Ziller spent the last three days of December 1944
at Erprobungsstelle Rechlin, where he made a total of five flights
in the Me 262. These flights provided Ziller with an opportunity
to become familiar with the operation and characteristics of the
Jumo 004 turbojet engine. At the end of a second successful test
flight on February 3, 1945, Ziller deployed the aircraft’s braking
parachute too soon on his landing approach. The result was a hard
landing which damaged the aircraft’s main undercarriage.
Consequently, the third test flight in the Horten H IX did not
take place until February 18, 1945. Returning after about 45
minutes in the air, Ziller was seen to dive the aircraft and pull
up several times at an altitude of about 800 meters, apparently in
an effort to relight an engine. The undercarriage was lowered
unusually early, at an altitude of about 400 meters. The V2’s
speed decreased and, accompanied by increasing engine noise, its
nose dropped and the aircraft entered a right-hand turn.
The H IX
completed a 360 degree turn with its wings banked 20 degrees. It
then accelerated and completed a second and third 360 degree turn,
the angle of bank increasing all the while. As it began a fourth
circle, the aircraft struck the frozen turf beyond the airfield
boundary. Walter Rosier was the first Horten employee to reach the
crash site, about two-and-a-half minutes after the accident. In
his report he stated: “The first thing I saw was the two Junkers
engines lying on the other side of the embankment. I could hear
the turbine running down in the still-warm left power plant, while
there was not a sound from the cooled-off right engine which lay
beside it. There was a strong smell of fuel, but no fire. Other
than the jet engines and Plexiglas cockpit hood, the aircraft had
been completely destroyed.
Like the engines, Ziller was ejected
from the aircraft on impact. He was thrown against a large tree
and killed instantly. Ziller had not used his radio, and had
continued to fly the aircraft with an engine out and the
undercarriage extended. He did not attempt to use his ejection
seat and parachute to safety, and the aircraft’s canopy was not
jettisoned. It seems certain that he was attempting to save the
valuable aircraft. What had happened? The empty compressed air
bottle in the wreckage confirmed that the under-carriage had
been lowered with compressed air after a loss of hydraulic power
following the failure of an engine.
Had there been a stall,
beginning at the right wingtip? Had the test pilot been rendered
unconscious and unable to react by carbonising oil from the
remaining engine, which had eventually overheated? (There were no
bulk-heads separating the cockpit from the engine bays.)
Unfortunately, only Leutnant Ziller could have answered these
questions, and he had failed to survive. In the opinion of the
investigating experts sabotage could not be ruled out.
Horten H IX 113, RLM-Number 8-229
The H IX VS was an unarmed, twin-jet, single-seat
aircraft. Further production of the fighter-bomber was assigned to
the Gothaer Waggonfabrik (GWF). Well-known for its Go 241 cargo
glider, Gotha was considered the company best suited to
manufacture Horten aircraft. The aircraft’s turbojet engines were
installed splayed 15 degrees left and right of the aircraft
centreline and 4 degrees nose down. The new installation was
tested in a centre section mock-up. Construction of the H IX V3
was nearly complete when the Gotha Works at Friederichsroda was
overrun by troops of the American 3rd Army’s VII Corps on April
14, 1945. The aircraft was assigned the number T2-490 by the
Americans.
The aircraft’s official RLM designation is uncertain,
as it was referred to as the Ho 229 as well as the Go 229. Also
found in the destroyed and abandoned works were several other
prototypes in various stages of construction, including a two-seat
version. The V3 was sent to the United States by ship, along with
other captured aircraft, and finally ended up in the H. H. “Hap”
Arnold collection of the Air Force Technical Museum. The all-wing
aircraft was to have been brought to flying status at Park Ridge,
Illinois, but budget cuts in the late forties and early fifties
brought these plans to an end. The V3 was handed over to the
present-day National Air and Space Museum (NASM) in Washington
D.C.
the remains of the centre-section of the V3 in
Maryland
The H XVIII was to be a six engined long-range
bomber.
The steel tube centre section was under
construction when
the works was over-run by the Allies