The NASM (National Air and Space Museum) is a Smithsonian Institute museum dedicated to the history and technology of aviation and spaceflight, one of whose locations is the Steven F. Udvar-Hazy Center, near Dulles Airport. It’s a place that will delight any enthusiast who visits, offering the chance to discover fascinating artifacts like the original prototype of the Horten Ho 229, an advanced jet-powered fighter-bomber built by Nazi Germany in the final stages of World War II. Though it never saw action, it is believed to have potentially inspired the first documented UFO sightings in 1947.
The reason this aircraft is preserved in the United States, alongside attractions like the Wright brothers’ invention, the Spirit of Saint Louis with which Lindbergh crossed the Atlantic, the Enola Gay that dropped the atomic bomb on Hiroshima, the Bell X-1 used by Yeager to break the sound barrier, the Apollo 11 module that first landed on the Moon, and the Air Force One used by President Kennedy, is linked to Operation Paperclip, which we’ve discussed on other occasions.
Operation Paperclip, initially known as Operation Overcast, aimed to bring German scientists to the U.S. who specialized in developing advanced weaponry that the Nazi regime had pushed from 1944 onward in a desperate attempt to turn the tide of the war. The operation also sought their groundbreaking inventions, such as the V-2 rockets, the Messerschmitt Me 262, and their atomic research. In short, any technological or medical advancement was highly coveted.

In March 1945, General Patton’s Third Army crossed the Rhine River, penetrating German territory, while Task Force Baum—dispatched by the colorful Lieutenant General to free a prisoner-of-war camp holding his son-in-law—failed in its mission. By April, however, German resistance had significantly weakened, and U.S. troops began capturing thousands of German soldiers. It was in this context that they stumbled upon a glider and a nearly completed prototype of the Horten, constructed from steel and wood.
This discovery was significant, as the U.S. Air Force had been working on jet aircraft for some time, but the power generated by the Westinghouse J30 engine was inferior to that of the BMW 003A used in the Horten. As a result, the Ho 229 V3 was transported to the Royal Aircraft Establishment, a military research center in Farnborough, England, where attempts were made to adapt its airframe to a British engine. However, this proved impossible due to excessive differences between the components.
The Horten Ho 229 was the brainchild of Hermann Göring, Reich Vice-Chancellor, Air Minister, and Commander-in-Chief of the Luftwaffe. In 1943, he had tasked engineers with developing a light bomber capable of meeting the so-called “3 x 1,000” requirement: carrying 1,000 kilograms of bombs, achieving a range of 1,000 kilometers, and reaching a speed of 1,000 kilometers per hour. Why these numbers? While German aircraft could reach the British Isles, drop their deadly payload, and return, they often suffered heavy losses to RAF fighters.

Göring’s request necessitated jet engines, which had already been under development and were being applied to new Junkers models with Jumo 004 engines—a type of turbojet that met Göring’s specifications but had a major drawback: excessive fuel consumption. A solution to this issue was found by adopting an innovative, revolutionary design—a lightweight, delta-wing airframe known as Nurflügel (Flying Wing).
This idea originated with brothers Walter and Reimar Horten, combat pilots from Bonn who, in the early 1930s, while members of the Hitler Youth, had built gliders with this shape (the Treaty of Versailles prohibited Germany from manufacturing powered aircraft). These early models were simple and aerodynamic but uncomfortable to operate, as the pilot had to lie face down in a small cockpit. Nevertheless, they formed the basis for what came later, including a 1935 iteration with an engine.
The Horten brothers began World War II on the front lines, piloting Messerschmitt Bf 109s; Walter even achieved nine victories during the Battle of Britain under the command of ace Adolf Galland, while Reimar stopped flying in 1940 to focus on his mathematics doctorate (a third brother, Wolfram, also a pilot, died at Dunkirk). When Germany was faring well in the war, the Hortens’ work received little attention. However, as the tide turned in 1942, they were granted half a million Reichsmarks for their research.

From their efforts and imagination emerged two distinct but conceptually similar projects grouped under the common designation Horten HV: twin-engine aircraft that continued an earlier project the brothers had built in the late 1930s and early 1940s, which itself was an evolution of their earlier glider. Their main features included the delta-wing airframe, the lightweight material (a resin that compensated for the limited power of the twin propeller engines), and a fixed landing gear.
Two units of the HV were built, differentiated by the fact that in the second version, the pilots no longer had to fly lying down. The first unit was disappointing, as it crashed during takeoff on its maiden flight. It was piloted by Walter, who survived by shutting down the engines and gliding, minimizing the impact with the ground. The second unit, on the other hand, seemed more promising, although its construction was delayed until 1942 in favor of better alternatives. Ultimately, it also met an unfortunate end, paving the way for the Horten H.VII. This was a training aircraft, nearly identical to its predecessor but equipped with more powerful engines.
Two prototypes were built, and Walter piloted one in several test flights. Subsequently, about twenty units were ordered; the H.VII V-3, which was to be the first, was nearly completed at the Peschke factory (Minden, Westphalia) when the arrival of Allied forces forced the work to halt and everything to be destroyed. Nevertheless, the Soviets took what remained of one unit to attempt to reconstruct it. According to U.S. officers from Project Sign, which investigated UFOs, some flying saucer sightings might have actually been versions of the H.VII V-3 rebuilt in the USSR.

Alternatively, they could have been attempts made in the U.S. by Northrop Corporation, known to have built a replica from the aircraft confiscated by Patton and conducted test flights in New Mexico. In fact, the first documented sighting was by a pilot from Idaho named Kenneth Arnold, who in 1947 claimed to have seen a formation of nine flying objects from his small aircraft while searching for a missing plane. What is particularly interesting is that he described them as boomerang- or crescent-shaped, although authorities dismissed them as merely reflections.
Returning to World War II, prior to the H.VII V-3, the Reichsluftfahrtministerium (Aviation Ministry) approved the Horten brothers’ proposal for a light bomber under the 3 x 1,000 concept and commissioned three HV units, though they required the aircraft to be equipped with two 30 mm cannons to also exploit its speed for potential use as a fighter. The manufacturing was entrusted to the Gothaer Waggonfabrik aerospace company, compensating for the rejection of its own flying wing project.
This led to the production of the Ho 229, whose first model, the H IX, was of mixed composition: the central section and pilot’s cockpit were constructed from steel tubing, while the wings were made from plywood combined with sawdust and charcoal. These materials were used due to the scarcity of lightweight alloys in Germany at that stage of the war. Fortunately, the Horten brothers had experience with alternative fuselage designs.

The pilots barely had room to move, but they had a pressurized suit, an ejection seat, and other advancements compared to the prototypes: the landing gear was retractable, and a parachute could be deployed as a complementary brake during landing. However, the first to fly on March 1, 1944, was the H.IX V1, with fixed wheels and no engine. Ten months later, after addressing some detected issues, it was time to test with engines: the H.IX V2, equipped with a Jumo 004 because the designated engine, a BMW 003, was not yet available.
It performed as expected, and Göring, enthusiastic, not only ordered forty units but also entrusted the Horten brothers with another project: the Amerikabomber, a long-range bomber capable of crossing the Atlantic and reaching the United States and returning. The proposals until then were based on conventional multi-engine planes such as the Messerschmitt Me 264, the Focke-Wulf Fw 300, the Focke-Wulf Ta 400, and the Junkers Ju 390; there was also consideration of the possibility that a Heinkel He 177 could transport a Dornier Do 217, releasing it midway over the ocean.
The Hortens radically changed all that by introducing their innovative delta wing concept. The Ho XVIII was an intercontinental version of the Ho 229, larger and equipped with six Jumo 004 turbojets, whose enormous fuel consumption was offset by the fact that the aircraft was made of wood bonded with a special carbon glue (which absorbed electromagnetic waves and, along with the paint, made it difficult to detect by radar). It had two turrets with two 30 mm cannons each and could carry four tons of bombs.

To the brothers’ dismay, the engineers from the manufacturers, Junkers and Messerschmitt, introduced modifications such as the removal of defensive armament and the reduction of engines to four. These changes did not have much significance because neither the Ho XVIIIa nor a variant developed exclusively by Junkers and Messerschmitt, the Ho XVIIIb, left the factory, as production was scheduled to begin in the fall of 1945, and the war ended before the assembly of the first unit was completed.
Meanwhile, the Ho 229 program continued. Walter and Reimar, occupied with their new mission, did not attend the test flights conducted by Lieutenant Erwin Ziller, who died during the third flight in February 1945, when one of the turbojets failed, causing the aircraft to plummet. The pilot tried to restart the engine several times but was unsuccessful, and the prototype crashed into the ground, consumed by fire except for what was pulverized on impact. This did not halt the work, as news arrived that the enemy had just launched Operation Lumberjack, the crossing of the Rhine.
Consequently, the Ho 229 was added to the Jäger-Notprogramm, or Emergency Fighter Program, which was part of the desperate effort by the Nazi regime to halt the enemy, the famous Wunderwaffe or “Wonder Weapons.” The facilities were moved to Friedrichroda, in Thuringia, and work began on the third prototype, the Ho 229 V3. It was slightly larger, and twenty units were to be built, but there was no time, as Patton’s troops arrived, finding the four prototypes along with a glider.

When Germany surrendered, Reimar Horten attempted to negotiate its handover to the British and Chinese, but ultimately fled to Argentina, where he continued designing aircraft. One of them, in 1953, was the supersonic twin-engine FMA I.Ae. 37, also delta-wing-shaped; it was never mass-produced due to delays caused by economic problems, ultimately rendering it obsolete, and the plan was canceled in 1961. He also designed the DINFIA I.Ae. 38 Naranjero, named for being a cargo plane intended to transport oranges; it had the same peculiar shape… and the same fate.
Walter, on the other hand, chose to stay in Germany and continued being part of the air force until 1951, when during the Cold War, Germans were authorized to build airplanes again; he then designed the Ho 33 glider, to which a motor was permitted to be added in 1957, though it did not perform as expected. Both brothers continued designing aircraft, all based on their delta wing concept, until their deaths: Reimar in Argentina in 1994; Walter in Germany four years later.
Aside from ideology (they were members of the Nazi Party but mere rank-and-file members without responsibilities in it), the innovative aeronautical spirit they embodied survives through their masterpiece, the Ho 229 V3, which, as mentioned at the beginning, is displayed in the Paul E. Garber Facility of the aforementioned American museum, partially restored though somewhat lackluster, with its wings separated from the central section.
This article was first published on our Spanish Edition on September 8, 2023: El insólito bombardero alemán de la Segunda Guerra Mundial con forma de ala delta, considerado posible causa del avistamiento de los primeros OVNIS
SOURCES
Lance Cole, Secret wings of World War II. Nazi technology and the Allied arms race
Davis Myhra, Horten 229
Mike Bennett, A brief history of science with levity
Emily Schmitt, Desperate for victory, the Nazis built an aircraft that was all wing. It didn’t work
Johannes Wehrmann, Gotha Go 229 – Horten Ho IX
Wikipedia, Horten Ho 229
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