airfoil technology
piston aero engines
jet engines
slotted wings and wing additions
development of swept wings
Horten flying wings
Northrop flying wing
forward-swept wings
delta wings
variable-sweep wings
supercritical airfoil
the monoplane
variable pitch propellers
metal skinned aircraft
retractable landing gear
NACA engine cowling
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aircraft noise reduction
V 2 missile technology
early X Planes
X15 and hypersonics
Nord Gerfault X-plane
lifting bodies
VTOL and STOL Aircraft
Soviet composite Aircraft
technology of landing
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development of autopilots
aircraft simulators
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Unmanned Aerial Vehicles
Nuclear powered aircraft
the area rule
air defence

the Horten flying wing

nothing is new under the sun

Early studies of delta wings led aircraft designers to ask if an entire airplane could consist only of a wing, with basically no fuselage whatsoever. Such all-wing aircraft would have excellent payload and range capabilities because they would produce less drag than a conventional aircraft. This was true because the tail and fuselage normally cause a significant amount of drag. Eliminate the tail and fuselage and you have eliminated a great deal of drag, enhanced performance, reduced the amount of fuel required, and generally improved the handling capabilities of the airplane. These so-called flying wing designs were long a dream of a number of designers but did not become practical until recently. The biggest problem found when building a flying wing aircraft is that such designs are inherently unstable and they do not easily stay level in flight.

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.

Horten V b, W-NT. 9

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