As Nazi Germany hurtled towards its inevitable and chaotic collapse, a sense of desperate innovation gripped its military aviation sector. In a frantic bid to turn the tide of war, no concept was deemed too outlandish, no configuration too unorthodox to be explored. This period birthed a fascinating, albeit ultimately futile, array of secret weapons for the Luftwaffe. Here are 23 of these ambitious, yet failed, designs that couldn’t save Hitler’s regime.
1. Arado E.381: The Miniature Menace
Dubbed the ‘Kleinstjäger’ or ‘Smallest Fighter’, the Arado E.381 was conceived to maximise the survivability of interceptors against Allied bombing raids by presenting an incredibly small target. Its frontal cross-section was a mere quarter of that of a Messerschmitt Bf 109, and it boasted substantial armour plating.
Pilot comfort, however, was a significant casualty of its design. The unfortunate aviator was confined to a prone position within a sealed, armoured tube, with visibility limited to a small, armoured windscreen. A 30mm cannon was mounted above the pilot, and tanks of highly toxic fuel were positioned on either side of his legs.
Designed to be air-launched from a four-engined Arado Ar 234C bomber, the E.381 would ignite its rocket motor, execute a maximum of two attack passes on enemy bombers, and then use its speed to escape. A braking parachute would then deploy to slow it sufficiently for a landing on a skid. While glider prototypes were constructed for testing, the E.381 proved too ambitious even for the faltering Third Reich. The primary issue was the vulnerability of the Arado mothership, and the prohibitive fuel requirements to ferry the fighter to altitude were unsustainable for an oil-starved Germany. The project was ultimately abandoned.
2. Bachem Ba 349 Natter: The Human-Guided Missile
There’s a certain grim irony when a pilot’s aircraft isn’t designed for complete survival during its mission. The Bachem Ba 349 Natter, or ‘grass snake’, was designed so that the pilot and its precious rocket engine could be safely parachuted back to Earth, leaving the rest of the wooden airframe to its fate. This SS project, designed by Erich Bachem, is perhaps best viewed as a human-guided surface-to-air missile.
The Natter was intended to be launched vertically and flown automatically to the altitude of attacking bombers. Once in position, the pilot would aim the aircraft and unleash its armament of 33 R4M rockets.
Following the engagement, the pilot was to jettison the nose cone, release his seatbelt, and deploy a braking parachute at the rear, which would propel him forward for a conventional parachute descent. In tests, the Natter demonstrated excellent gliding capabilities, and the system functioned as planned with a dummy pilot. However, the sole manned powered flight ended in tragedy. Lothar Sieber, the first human to be vertically launched by a rocket-powered vehicle, was killed when his Natter crashed just 32 seconds after launch. Designer Erich Bachem, remarkably, survived the war and went on to produce a successful range of ‘Eriba’ caravans.
3. Blohm and Voss BV 40: The Armoured Glider
Blohm & Voss proposed a small, armoured glider designed to destroy Allied bombers by diving at high speed and ramming their tails. A 30mm cannon was initially incorporated to counter rear gunners, but the ramming concept was eventually abandoned in favour of conventional gun attacks.
The diminutive BV 40, piloted in a prone position, was to be towed to altitude, then dive at speeds approaching 560 mph, engage a bomber, and escape. Despite concerns about the vulnerability of both the glider and its tug aircraft during ascent, 21 BV 40s were ordered, with six eventually built. Ironically, all six were destroyed in an Allied bombing raid on October 6, 1944.
4. Blohm & Voss BV 246 Hagelkorn: The Cement Glider Bomb
Continuing with the glider theme, Blohm & Voss developed the BV 246 Hagelkorn, or ‘Hailstone’. This was a guided glide bomb designed to be released up to 130 miles from its target and glide towards it in a high-speed dive. A remarkable aspect of this design was that the slender wings of the Hagelkorn were constructed from cement.
Early testing revealed the weapon to be woefully inaccurate. However, in 1945, its accuracy was significantly improved with the addition of the Radieschen passive seeker, which homed in on Allied radar transmitters, effectively making it the world’s first anti-radiation weapon. Approximately 1,000 units were built, but none were ever deployed in combat.
5. Messerschmitt Me 263: The Rocket Interceptor’s Successor
The rocket-powered Messerschmitt Me 163 Komet was renowned as the fastest aircraft of the conflict, but it was also notoriously impractical and fraught with dangerous features. Its most significant failing from the Luftwaffe’s perspective was its extremely limited endurance of just 8 minutes.
Its intended successor, the Me 263, inherited the volatile fuel and questionable tailless design of the Me 163. The latter’s aerodynamic quirk made it prone to an unrecoverable ‘graveyard dive’ if its speed exceeded Mach 0.84. The Me 263, however, featured a new engine promising a 12-minute endurance.
While still brief, this 50% increase in powered flight time, coupled with the aircraft’s absurdly high rate of climb, offered a meaningful improvement in intercepting Allied bombers. A retractable undercarriage was also incorporated, a welcome improvement over the skid fitted to the Me 163, which contributed to numerous landing accidents. Unfortunately for the Me 263, it was not part of the Emergency Fighter Programme, making resource acquisition difficult. Despite this, a prototype was completed and flown as a glider, but no powered flights were achieved before the war’s end. The design was later developed by the Soviet Union into the post-war MiG I-270.
6. Mistel: The Composite Bomb Aircraft
In the twilight of the war, Germany faced shortages of fuel, aircrew, and raw materials. However, it possessed an abundance of obsolete aircraft and rather outlandish ideas. The remarkable Mistel project was an intriguing scheme to transform unwanted, older bombers into flying bombs.
This composite aircraft comprised a Messerschmitt Bf 109 or Focke-Wulf Fw 190 mounted atop an explosive-laden Junkers Ju 88. The Mistel composite would fly directly towards its target, at which point the fighter would detach, allowing the unmanned bomber to continue its trajectory and, hopefully, destroy the objective.
Operational Mistels replaced the Ju 88’s cockpit with a shaped explosive charge weighing nearly two tonnes and a prominent detonator. Mistels were deployed against the D-Day invasion fleet in 1944 and targeted bridges in an attempt to impede the advance of Soviet armies into Germany. However, their impact was negligible, and the Red Army’s progress was only slightly delayed.
Ultimately, the Mistel’s effectiveness was hampered by the lack of a precise guidance system for the bomber. To address this, a projected Mistel variant featured a Messerschmitt Me 262 equipped with a cockpit for a pilot to remotely guide a second, unmanned, explosive-laden Me 262 onto its target. However, this concept remained on the drawing board by Victory in Europe Day.
7. Focke-Wulf Ta 183 Huckebein: The Jet Successor That Never Was
The Focke-Wulf Ta 183 Huckebein was envisioned as the Luftwaffe’s jet successor to the Me 262, but it never progressed beyond model form before the Reich’s collapse. Designed by Kurt Tank and Hans Multhopp, it earned the nickname “Huckebein” from a mischievous raven in a popular children’s book. Post-war, under Tank’s direction, it influenced Argentina’s Pulqui II project.
The Ta 183 featured boldly swept wings, a compact fuselage, and was intended to be powered by Heinkel’s HeS 011 turbojet, though prototypes were initially slated to use the Jumo 004B. A rocket boost option was also considered, aiming to provide an exceptional rate of climb for the aircraft’s primary role as a bomber interceptor.
Aerodynamically daring, the design positioned the wings unusually far forward and was constructed largely of wood to conserve aluminium. The wing incorporated elevons for both pitch and roll control, though stability concerns persisted. Four MK 108 cannons formed the primary armament, with provisions for bombs or guided missiles mounted semi-internally beneath the fuselage. By mid-1944, Germany’s Emergency Fighter Programme initially favoured Junkers’ EF 128, but then deemed the Ta 183 the superior design. Sixteen prototypes were ordered, with a first flight anticipated in May 1945. However, Focke-Wulf’s factory in Bremen was captured by British forces before the prototypes could be completed.
8. Junkers Ju 390: The Transatlantic Ambition
The Junkers Ju 390 was conceived as a long-range strategic aircraft, essentially a stretched variant of the impressive Ju 290, powered by six BMW 801 engines. Its immense wingspan and enlarged fuselage hinted at intercontinental ambitions, and it was Junkers’ entry into the Amerikabomber competition, aimed at developing a transatlantic aircraft capable of attacking the United States.
Persistent tales circulate of a Ju 390 flight from France to within sight of the American coast in 1944, a round trip to Cape Town, South Africa, and a transport flight to Japan over the North Pole. However, concrete documentary evidence for these claimed flights remains elusive, and most historians doubt their occurrence.
What is certain is that two prototypes were completed, and their operational contribution was negligible. One served briefly in transport and reconnaissance roles, but the type never entered mass production. Logistical challenges, strained resources, and the deteriorating war situation effectively doomed the project. Nevertheless, the Ju 390 occupies a peculiar place in wartime lore. Its enormous dimensions symbolised German technological ambition as the Third Reich crumbled, while the legends surrounding its transatlantic reach fuelled post-war fascination. More myth than menace, it endures as a reminder of how desperation bred innovation and how mythology can emerge in the absence of hard facts.
9. Horten Ho 229: The Flying Wing Jet
The Horten Ho 229 was a jet-powered flying wing aircraft designed by brothers Reimar and Walter Horten. Its construction made extensive use of wood and other non-strategic materials due to wartime shortages, while its distinctive shape stemmed from the Hortens’ long-standing interest in tailless flying wing designs.
Several prototypes were built, beginning with gliders and followed by powered versions fitted with Junkers Jumo 004 turbojet engines. Development was cut short by the war’s end. However, unlike most late-war German projects, the Ho 229 did reach the flight-test stage, with its first flight occurring on February 2, 1945.
On its third flight, an engine fire led to the loss of the aircraft and the death of test pilot Erwin Ziller. Work continued, however, as Luftwaffe chief Hermann Göring was keen on the design and had already ordered a production series of 40 aircraft from Gotha before the prototype had even flown. No further aircraft were completed before the war’s end. Today, a nearly complete prototype, captured and shipped to the US for evaluation, is preserved as part of the Smithsonian collection. This is the only genuine German prototype jet to survive the war.
10. Horten H.XVIII: The Transatlantic Bomber Concept
The Horten H.XVIII was another late-war German flying wing project conceived by the Horten brothers. Intended as a transatlantic bomber capable of attacking targets in the continental United States, its sleek, tailless configuration promised low drag, fuel efficiency, and potentially reduced radar visibility, though the latter was a secondary concern.
Essentially a scaled-up version of the Ho 229 fighter, the H.XVIII was designed to be built primarily of wood. It was intended to jettison its undercarriage after take-off and land on a skid. The project was ultimately abandoned due to Germany’s deteriorating war situation.
11. Arado E.555: The Atlantic Jet Bomber
The Arado E.555 was another long-range jet bomber concept intended to strike targets across the Atlantic. Unlike the pure flying wing of the Hortens, the E.555 featured fins and rudders, external jet engines mounted above the centre section, and a small fuselage pod for the crew. Several variants were envisioned, including long- and medium-range models, but none were built.
Plagued by technical challenges, resource shortages, and the worsening war situation, the E.555, like many other German wartime projects, demonstrated that while German planners were not short on ambition, they were woefully deficient in comprehending the reality of their strategic position.
12. Silbervogel: The Rocket Bomber Spacecraft
Of all the audacious ideas conceived to save the Third Reich, the suborbital Raketenbomber, or ‘Rocket Bomber’, was perhaps the most outlandish. Yet, this was also history’s first serious proposal for a low orbital spacecraft, and remarkably for a project developed under the chauvinistic Nazis, it was co-designed by a woman.
The brainchild of Eugen Sänger and Irene Bredt, the Raketenbomber, named ‘Silbervogel’ (Silverbird), was, to put it mildly, the most ambitious of the Amerikabomber proposals. Accelerated to 1,200 mph on a rail-mounted rocket sled, once airborne, its own rocket engine would propel it to a staggering 13,500 mph.
After climbing to an altitude of 90 miles, the aircraft was intended to “bounce” off the stratosphere in a series of progressively smaller skips, allowing it to drop an 8,800 lb (4,000 kg) weapon on the continental US before landing in Japan, completing a journey of approximately 15,000 miles. Although never built, the project intrigued Stalin enough that an attempt was made in 1949 to kidnap Sänger and Bredt, but it was unsuccessful. Perhaps to celebrate their escape, the two scientists married in 1951. Modern analysis revealed a critical flaw in the calculations regarding the heat the Silbervogel would encounter upon re-entry, suggesting it would have been destroyed if flown.
13. Focke-Wulf Baubeschreibung Nr.264: The Single-Engine Fighter Concept
The German Ministry of Aviation (Reichsluftfahrtministerium, RLM) was aware of the incredible capabilities of the Me 262, then in development, with its astonishing top speed. However, its lack of manoeuvrability and the lavish use of dwindling materials were significant issues. With this in mind, in 1943, the need for a single-engine fighter was expressed.
An extremely high ceiling and top speed were demanded, with range and endurance being secondary considerations. The planned armament comprised two stubby 30mm calibre MK 108 autocannons mounted in the fuselage straddling the pilot, and two longer-barrelled MG 151s in the wing roots.
With its under-fuselage intake, the design foreshadowed later jet aircraft like the Crusader and F-16. However, this configuration was rejected due to the risk of damage to the aircraft in the event of belly landings. The engine was subsequently relocated to the top of the aircraft, which resulted in an unacceptable drop in expected performance. It was theorised that this performance deficit could be overcome with the addition of two rockets. At this point, a twin-boom configuration appeared to be a more viable solution, and Focke-Wulf explored a design bearing some similarities to the contemporary De Havilland Vampire, known as the Flitzer, which never progressed beyond the mock-up stage.
14. Lippisch P.13a: The Coal-Powered Ramjet
Although it never flew under power, Alexander Lippisch’s incredible tailless delta P.13a did, at least, address Germany’s crippling late-war oil shortage. It was powered by a coal-burning solid-fuel ramjet, which fed powdered coal into a combustion chamber. Take-off would have required rockets or a catapult to reach the necessary speed for ramjet ignition.
Unlike many other projects, the aircraft reached the hardware stage in a limited capacity. The DM-1 glider was built to explore Lippisch’s delta aerodynamics. Concurrent wind-tunnel work suggested promising stability at very high speeds, though claims of Mach 2.6 are likely exaggerated.
By the time research was halted as Soviet and Allied forces overran Vienna, Lippisch had moved on to wind-tunnel testing the P.13b. This iteration moved the pilot from his cockpit in the large vertical fin to a more conventional nose-mounted nacelle and featured twin fins of less radical size, while retaining the coal-powered ramjet. Meanwhile, the DM-1 glider was transported to the US and tested in the full-scale wind tunnel at Langley. This testing revealed design flaws that NACA engineers rectified by adding sharp leading edges, a much thinner tail fin, and a cockpit canopy from the P-80 jet fighter. The extent of this aircraft’s influence on subsequent American delta designs remains a subject of much debate.
15. Focke Rochen: The Flying Stingray VTOL
The Focke Rochen was a Vertical Take-Off and Landing (VTOL) concept designed by Heinrich Focke, a co-founder of Focke-Wulf. Patented in 1939, Focke’s design featured a fuselage with a disc-like planform and an aerofoil profile, earning it the nickname “Rochen” (stingray). A central turbojet was intended to drive two large propellers housed within the fuselage.
The Rochen achieved forward flight by vectoring the downwash from the propellers rearward through a series of ventral louvres. The turbojet exhausts incorporated primitive afterburners, providing horizontal thrust. Development continued after the war, with wind-tunnel testing conducted in Bremen, and Focke submitted another patent for the aircraft in 1957. However, a full-scale Rochen has yet to be built.
16. Focke-Wulf Triebflügel: The Rotor-Powered Wonder
Another Focke-Wulf VTOL project, the Triebflügel, was arguably even more radical than the Rochen. Lift and thrust were provided by a rotor assembly situated between the tailplane and the cockpit. When positioned vertically on its tail, the rotors were intended to function like those of a helicopter.
During horizontal flight, these rotors would act as a giant propeller. As if this weren’t sufficiently unconventional, the rotors were to be powered by tip-mounted ramjets. The entire assembly was designed to land vertically (backwards) on a single, large wheel at the extreme tail, supported by outriggers. Despite its incredibly unconventional design, wind-tunnel testing had commenced by Victory in Europe Day.
17. Junkers Ju 287: The Forward-Swept Wing Jet
The Junkers Ju 287 aimed to enhance the take-off and landing performance of jet aircraft by incorporating a forward-swept wing, designed by Dr. Hans Wocke, to provide additional lift at low airspeeds. This design also allowed for a single bomb bay to be positioned ahead of the wing, directly above the aircraft’s centre of gravity.
The aircraft combined the new wing, constructed from scratch, with the fuselage of an He 177A-3 bomber, the tail of a Ju 188, and, remarkably, the main and nose wheels were salvaged from destroyed American Consolidated B-24 Liberators – a notable instance of wartime recycling. To save weight and maintain simplicity, the undercarriage was fixed.
Flight testing commenced on August 8, 1944, and the aircraft displayed generally excellent handling characteristics. However, some issues with wing warping were encountered, a particular challenge with forward-swept wing designs. These problems were expected to be resolved in the next prototype, which would feature all four engines mounted on the wings. However, that prototype remained incomplete by the end of the war. The remnants of the aircraft, along with Hans Wocke and his design staff, were captured by the Soviets and relocated to the USSR, where a developed version was flown as the EF.131 in 1947.
18. Fieseler Fi 103R Reichenberg: The Human-Guided V-1
The Fieseler Fi 103R Reichenberg was, in essence, a V-1 cruise missile equipped with a human as the guidance system. The Reichenberg underwent a rapid development period, likely too rapid. The German Research Institute for Sailplane Flight began development in mid-1944 and had a prototype ready for testing within days.
A cramped cockpit with a jettisonable canopy was positioned directly beneath the pulse-jet’s air intake, and flight controls were rudimentary, albeit straightforward. After release from a carrier aircraft, the Reichenberg was intended to be piloted towards a target and put into a dive, after which the pilot would bail out. Pilot survival was optimistically rated as “most unlikely,” with estimates suggesting a terrifying 1% chance due to the proximity of the pulse-jet’s intake to the cockpit.
Complicated landing controls resulted in two test articles crashing during developmental trials. Although the designers attempted to draw a distinction between their Selbstopfermänner (‘self-sacrifice men’) and the Japanese Kamikaze pilots, for the pilot, the difference was minimal. Thankfully for the young men expected to fly this screaming tomb, the project was quickly abandoned after armaments minister Albert Speer and KG200 chief Werner Baumbach successfully persuaded Hitler that suicide was not in the German warrior tradition.
19. Dornier Do 335 Pfeil: The Push-Pull Powerhouse
Dornier adopted a radical approach with its unique Do 335. To minimise frontal surface area, drawing on earlier experience with the Do 18 and the P.59 (a 1937 patent for a tractor-pusher bomber), the Do 335 employed the unusual ‘push-pull’ configuration, with both engines mounted within the fuselage. The forward engine was in the conventional tractor propeller location, while the aft engine was mounted in the middle of the fuselage for better weight distribution and connected to an aft push propeller via a driveshaft. This arrangement resulted in a frontal surface area only slightly larger than that of a comparable single-engine fighter.
A pair of Daimler-Benz DB-603 engines, each producing 1,800 hp, allowed for a maximum weight slightly higher than a traditional fighter. It was armed with a 30-mm cannon firing through the propeller hub and a pair of 20-mm cannons in the cowling. The aircraft could carry a significant amount of fuel, providing a combat range 30% greater than that of the Focke-Wulf Fw 190 or Messerschmitt Bf 109. The aircraft arrived too late to see combat in World War II; only 37 were built. Of these, a few reached conversion units for a short period, but the type never saw active service. The design produced tremendous performance, topping out at a remarkable 474 mph.
20. Heinkel He 162 Volksjäger: The People’s Fighter
Born in the desperate final days of Nazi Germany, the diminutive Heinkel He 162 ‘Volksjäger’ (People’s Fighter) was conceived with the hope that a mass-produced, inexpensive yet highly advanced design could defend against the hundreds of Allied bombers pounding Germany. Cheap manufacture was achieved through the exploitation of subterranean slave labour, resulting in appalling build quality.
The journey from conception to first flight took a mere three months. It was an extremely innovative design, combining the new technologies of jet propulsion and an ejection seat, and was intended to be flown by young, fanatical men (and boys) with minimal glider training. While an impressive achievement and capable of 550 mph, it proved difficult to fly.
In the final stages of the project, it became apparent that jet engines were too costly and consumed too many valuable materials. A simpler solution was considered: replacing the jet engine with one or two pulse jets, similar to those used on the V-1 missile. Another proposal involved the He 162 forming the upper component of a Mistel composite, mounted atop a massive air-launched bomb – the Ar 377 or Ju 268. The idea was for the He 162 to guide the bomb near its target before detaching. The bomb (or missile or drone, depending on classification) was essentially a twin-engine jet bomber in its own right.
21. Arado Ar 234 Blitz: The Fast Jet Bomber
Astonishingly, the fastest pure bomber of the war exceeded the speed of the speediest operational fighters of 1939 by over 100 mph. Initially too ambitious, the Ar 234 combined jet propulsion with a jettisonable trolley undercarriage (large fuselage fuel tanks left no room for internal undercarriage), rocket-assisted take-off, cabin pressurisation, and an ejection seat. It first flew on August 22, 1943.
Somewhat simplified, with a conventional undercarriage fitted into a larger fuselage, the first B-series aircraft flew on March 10, 1944. The Ar 234 was employed for reconnaissance and bombing missions. Despite its speed, it was not invulnerable and suffered from poor rearward visibility and relatively poor manoeuvrability at lower speeds.
The world’s first jet bomber attack occurred on Christmas Eve 1944. III./KG 76, under the command of Hauptmann Dieter Lukesch, dispatched nine Arado 234B-2s, each armed with a single 500 kg (1,100-lb) bomb, to attack rail yards at Liège during the Ardennes offensive. The mission was successful, with all bombers returning safely. Approximately a week later, on New Year’s Day, III./KG 76 attacked Allied airfields with six aircraft. Further missions followed throughout January. In March, Arado bombers were tasked with halting US advances across the Rhine at Remagen; five attempts were made, resulting in the loss of five Arados.
22. Messerschmitt Me 262A-2 Sturmvogel: The Stormbird’s Bomber Role
As with several aircraft on this list, Me 262 production was aided by slave labour from concentration camps. The Me 262 was primarily a fighter, but it also saw combat as a light bomber. Much has been made of Hitler’s alleged “mistaken” edict in May 1944 to develop this jet as a bomber, which purportedly delayed its service entry and negated its perceived “correct” use as a fighter.
The reality is more nuanced. The D-Day landings were imminent, the Me 262 was not yet in production, and the limited number of fighters that could be built in time would, at best, have had a minimal impact against overwhelming Allied numerical superiority. However, attacks from as few as 50 (uninterceptable) fighter-bombers against troops on the beaches could potentially have proven decisive.
But the invasion occurred before the Me 262 was available, rendering the question academic. Both fighter and fighter-bomber versions had been planned from the outset of the programme, and ultimately, the Me 262A-2 became the definitive bomber variant, capable of carrying two 250kg bombs. The Sturmvogel was slower than fighter variants of the Me 262, yet even loaded with bombs, it was still faster than any other bomber and almost every Allied fighter. Despite this, it achieved little. While flying fast helped avoid interception, bombing accuracy was poor. The greatest challenges, however, were a lack of fuel and aircrew, and most Sturmvogels never saw action at all.
23. Messerschmitt P.1101: The Variable Sweep Pioneer
The Messerschmitt P.1101 was a late-war German jet fighter prototype, developed under the Emergency Fighter Programme. Its most notable innovation was its ground-adjustable variable wing sweep. This concept served as a direct precursor to post-war variable geometry ‘swing-wing’ designs, which could alter their wing geometry in flight.
Developed under Dr. Woldemar Voigt, the P.1101 featured a short fuselage, tricycle landing gear, and a boom-mounted tail. Twin intakes were designed to feed the planned HeS 011 engine. By August 1944, the design had been refined with a slimmer nose and revised wings, but development was hampered by difficulties, including a cramped armament installation and complex landing gear.
Despite losing out to Focke-Wulf’s Ta 183, funding continued for a P.1101 prototype. Constructed at Oberammergau, the V1 prototype incorporated Me 262 wing sections, a single nose intake, and adjustable sweep angles ranging from 30 to 45 degrees. A Jumo 004 engine replaced the unavailable HeS 011. Planned armament included MK 108 cannons and Ruhrstahl X-4 guided missiles. Captured by US forces, the 80% complete prototype was shipped to America. Although too damaged to be completed or flown, its ‘swing-wing’ concept was further developed by Bell aircraft to produce the externally similar but more advanced Bell X-5, the first aircraft capable of changing its wing sweep in flight. The world would have to wait until the F-111 in 1967 for an operational variable geometry or ‘swing-wing’ aircraft.
