Horten Ho 229

Ho 229
	Artist's concept of the aircraft in the air
Role	Fighter/bomber
Manufacturer	Gothaer Waggonfabrik
Designer	Horten brothers
First flight	1 March 1944 (glider)
Primary user	Luftwaffe
Number built	3
Developed into	Gotha Go P.60

The Horten H.IX, RLM designation Ho 229 (or Gotha Go 229 for extensive re-design work done by Gotha to prepare the aircraft for mass production) was a German prototype fighter/bomber designed by Reimar and Walter Horten to be built by Gothaer Waggonfabrik. Developed at a late stage of the Second World War, it was the first flying wing to be powered by jet engines.[1]

The Ho 229 was designed in response to a call by Hermann Göring, the head of the Luftwaffe, in 1943 for light bombers capable of meeting the "3×1000" requirement; namely, to carry 1,000 kilograms (2,200 lb) of bombs a distance of 1,000 kilometres (620 mi) with a speed of 1,000 kilometres per hour (620 mph). Only jet propulsion could achieve the required speed, but such engines were relatively primitive and very fuel-hungry, necessitating considerable effort across the rest of the design to satisfy the range requirement. The flying wing configuration was favoured by the Horten brothers due to its high aerodynamic efficiency, as demonstrated by their Horten H.IV glider. In order to minimise drag, the Ho 229 was not fitted with extraneous flight control surfaces. Its ceiling was 15,000 metres (49,000 ft).[2] The Ho 229 was the only design that even came close to the requirements, and the Horten brothers quickly received an order for three prototypes after the project garnered Göring's approval.

Due to the Horten brothers lack of appropriate production facilities, Ho 229 manufacturing was contracted out to Gothaer Waggonfabrik; however, the company allegedly undermined the project by seeking the favour of Luftwaffe officials for its own flying wing design. On 1 March 1944, the first prototype H.IX V1, an unpowered glider, performed its maiden flight, followed by the H.IX V2, powered by Junkers Jumo 004 turbojet engines in December 1944. However, on 18 February 1945 the V2 was destroyed in a fatal crash, killing its test pilot. Despite as many as 100 production aircraft on order, none were completed. The nearly complete H.IX V3 prototype was captured by the American military and shipped to the United States under Operation Paperclip. It was evaluated by both British and American researchers before entering long term storage. The H.IX V3 is on static display in the Smithsonian National Air and Space Museum.

Design and development

Horten H.IX V2 before a test flight

During the early 1930s, the Horten brothers had become interested in the flying wing configuration as a method of improving the performance of gliders. At that time, the German government had been actively funding glider clubs across the country as a response to the production of military and even motorized aircraft being forbidden by the Treaty of Versailles after the First World War. The flying wing layout removed the need for a tail and associated control surfaces and theoretically offered the lowest possible weight, using wings that were relatively short and sturdy, and without the added drag of the fuselage. Their first aircraft of such a configuration was the Horten H.IV.[3][4]

In 1943, Reichsmarschall Hermann Göring issued a request for design proposals to produce a bomber that was capable of carrying a 1,000 kilograms (2,200 lb) load over 1,000 kilometres (620 mi) at 1,000 kilometres per hour (620 mph); the so-called "3×1000 project". Conventional German bombers were capable of reaching Allied targets across Great Britain, but were suffering devastating losses from Allied fighters in the process.[3] At the time, there was no conventional means for aircraft designers to meet these goals—the new Junkers Jumo 004B turbojets could provide the required speed, but had excessive fuel consumption. However, the Horten brothers concluded that the low-drag flying wing design could meet all of the goals: by reducing the drag, cruise power could be lowered to the point where the range requirement could be met. They put forward their private project, the H.IX, as the basis for the bomber.

The Government Air Ministry (Reichsluftfahrtministerium) quickly approved the Horten proposal, but ordered the addition of two 30 mm cannons, as they felt the aircraft would also be useful as a fighter due to its estimated top speed being significantly higher than that of any Allied aircraft.[4] German officials assigned the designation Ho 229 to the aircraft. Göring was reportedly impressed with the design and personally intervened to ensure that three prototypes were ordered at a cost of 500,000 ℛℳ.[4] At one point, the Air Ministry issued an order for 100 production aircraft, although this was subsequently curtailed to only 20 aircraft.[5] Furthermore, as the Horten brothers lacked appropriate production facilities, it was decided that the manufacturing of the aircraft would be handled by an established company, Gothaer Waggonfabrik.[6] This arrangement was somewhat complicated by Gothaer's alleged efforts to persuade German authorities to favour its own projects, which included flying wing designs, over the Ho 229.[7]

Observing the difficulties present in the Ho 229's design and development, Russell Lee, the chair of the Aeronautics Department at the National Air and Space Museum, speculated that an important motivating factor of the project for the Horten brothers was to prevent them and their workers from being assigned to more dangerous roles by the German military.[8] Looking beyond the Ho 229, the Horten brothers produced numerous flying wing designs, such as the Horten H.VII fighter-trainer and the Horten H.XVIII Amerikabomber.[9][4] According to the aviation historian Jean-Denis G.G. LePage, various other wartime projects were inspired by the Horten brother's work.[10]

The H.IX was of mixed construction; while the center pod was made from welded steel tubing, the wing spars were composed of pine.[11] The wings were made up of a pair of thin plywood panels that were glued together with a charcoal and sawdust mixture. The exterior was covered by a fireproof paint.[11] The wing had a single main spar, penetrated by the jet engine inlets, and a secondary spar used for attaching the elevons. It was designed with a 7g load factor and a 1.8× safety rating; therefore, the aircraft had a 12.6g ultimate load rating. The wing's chord/thickness ratio ranged from 15% at the root to 8% at the wingtips.[1] There was relatively little available interior space, making the addition of new equipment or more crew members either difficult or impossible.[12]

The aircraft was fitted with retractable tricycle landing gear, with the nosegear on the first two prototypes sourced from a He 177's tailwheel system, with the third prototype using an He 177A main gear wheelrim and tire on its custom-designed nosegear strutwork and wheel fork. A drogue parachute slowed the aircraft upon landing. The pilot sat on a primitive ejection seat. A special pressure suit was developed by Dräger. While the aircraft had originally been designed to be powered by the BMW 003 turbojet engine, this engine was not quite ready at the time, thus the Junkers Jumo 004 engine was substituted.[1] Flight control was achieved via a combination of elevons and spoilers. This control system included both long-span (inboard) and short-span (outboard) spoilers, with the smaller outboard spoilers activated first; it reported provided a smoother and more graceful control of yaw than would have been by a single-spoiler system.[1]

Operational history

Testing and evaluation

Horten IV glider (hanging, top)

On 1 March 1944, the first prototype H.IX V1, an unpowered glider with fixed tricycle landing gear, performed its maiden flight. Flight results were very favorable, but there was an accident when the pilot attempted to land without first retracting an instrument-carrying pole extending from the aircraft. Following the transference of design responsibility from the Horten brothers to Gothaer Waggonfabrik, the company's design team implemented several changes: they added a simple ejection seat, substantially redesigned the undercarriage to enable a higher gross weight, changed the jet engine inlets, and added ducting to air-cool the jet engine's outer casing to prevent damage to the wooden wing.[1]

The H.IX V1 was followed in December 1944 by the Junkers Jumo 004-powered second prototype H.IX V2; the BMW 003 engine had been preferred but was not available in sufficient quantity. Göring believed in the design and ordered a production series of 40 aircraft from Gothaer Waggonfabrik with the RLM designation Ho 229, even though it had not yet taken to the air under jet power. On 2 February 1945, the first flight of the H.IX V2 was conducted at Oranienburg.[3] The Horten brothers were unable to witness this flight as they were occupied with producing the design for a new turbojet-powered strategic bomber in response to the Amerikabomber competition. All of the subsequent test flights and development were conducted by Gothaer Waggonfabrik. The test pilot was Leutnant Erwin Ziller. Two further test flights were performed: on 2 February 1945 and on 18 February 1945.

Two weeks later, on 18 February 1945, disaster struck during the third test flight. Ziller took off without any problems to perform a series of flight tests. After about 45 minutes, at an altitude of around 800 m, one of the Jumo 004 turbojet engines developed a problem, caught fire and stopped. Ziller was seen to put the aircraft into a dive and pull up several times in an attempt to restart the engine and save the precious prototype.[13] Ziller undertook a series of four complete turns at 20° angle of bank. Ziller did not use his radio or eject from the aircraft. He may already have been unconscious as a result of the fumes from the burning engine.[4] The aircraft crashed just outside the boundary of the airfield; Ziller was thrown from the aircraft on impact and died from his injuries two weeks later. The prototype aircraft was completely destroyed.[13][14]

Unloading of captured Horten Ho 229 V3 in the U.S.

Despite this setback, the project continued with sustained energy. On 12 March 1945, nearly a week after the U.S. Army had launched Operation Lumberjack to cross the Rhine River, the Ho 229 was included in the Jäger-Notprogramm (Emergency Fighter Program) for accelerated production of inexpensive "wonder weapons". The prototype workshop was moved to the Gothaer Waggonfabrik (Gotha) in Friedrichroda, western Thuringia. In the same month, work commenced on the third prototype, the Ho 229 V3.

The V3 was larger than previous prototypes, the shape being modified in various areas, and it was meant to be a template for the pre-production series Ho 229 A-0 day fighters, of which 20 machines had been ordered. The V3 was meant to be powered by two Jumo 004C engines, with 10% greater thrust each than the earlier Jumo 004B production engine used for the Me 262A and Ar 234B, and could carry two MK 108 30 mm cannons in the wing roots. Work had also started on the two-seat Ho 229 V4 and Ho 229 V5 night-fighter prototypes, the Ho 229 V6 armament test prototype, and the Ho 229 V7 two-seat trainer.

In April 1945, George Patton’s Third Army found four steel-and-wood Horten prototypes; a Horten glider and the Ho 229 V3, which was undergoing final assembly, were captured. Of three airframes, the V3 was nearest to completion, and was shipped to the United States for evaluation.[11] Along the way, the Ho 229 spent a brief time at RAE Farnborough in the UK, during which it was evaluated as to whether British jet engines could be installed, but the mountings were found to be incompatible with the early British turbojets,[15] which used larger-diameter centrifugal compressors as opposed to the slimmer axial-flow turbojets the Germans had developed. The Americans were just starting to create their own axial-compressor turbojets before the conflict's end, such as the Westinghouse J30, with a thrust level only approaching the BMW 003A's full output. It is uncertain if the aircraft's original Junkers-supplied engines were ever ran, although the American evaluation team at one point had the intention of flying it.[11]

Surviving aircraft

The only surviving Ho 229 airframe, the V3—and the only surviving Second World War-era German jet prototype still in existence—is on display in the main hall of the Steven F. Udvar-Hazy Center of the Smithsonian National Air and Space Museum (NASM) alongside other WWII-era German aircraft.[16] It is displayed partially restored, the wings of the aircraft displayed separately from the center section.

Prior to being placed on display in 2017, it was stored at the NASM's Paul E. Garber Restoration Facility in Suitland, Maryland, U.S. In December 2011, the National Air and Space Museum moved the Ho 229 into the active restoration area of the Garber Restoration Facility, where it was reviewed for full restoration and display.[17]

Horton 229 V3 in 2016 at Mary Baker Engen Restoration Hangar

Horton 229 in 2016 while the center section (left) was under restoration. Wings stored separately (right).

The central section of the V3 prototype was moved to the NASM's Steven F. Udvar-Hazy Center in late 2012 to commence a detailed examination of it before starting any serious conservation/restoration efforts[18] and was cleared for the move to the Udvar-Hazy facility's restoration shops by summer 2014.[19] Following work performed within the Udvar-Hazy facility's Mary Baker Engen Restoration Hangar, it was put on display.[20]

Claimed stealth technology

Radar absorbent material

Cross-section of the Horten Ho 229 composite wood laminate

In 1983, Reimar Horten stated that he intended to mix charcoal dust in with the wood glue to absorb electromagnetic waves (radar), which he believed could shield the aircraft from detection by the British early-warning ground-based radar that operated at 20 to 30 MHz (10 to 15m wavelength), top end of the HF band, known as Chain Home.[lower-alpha 1][11][21] This charcoal glue treatment was planned for the never-made production model; however, it remained unclear if the V3 prototype had benefited from a preliminary iteration of this technology.[21]

During 2008, a team of engineers from Northrop Grumman undertook electromagnetic tests on the V3's multilayer wooden centre-section nose cones. They tested over a frequency range of 12 to 117 THz, with wavelengths of the order of 10 microns. The cones are 19 mm (0.75 in) thick and made from thin sheets of veneer. The team observed that the "Ho 229 leading edge has the same characteristics as the plywood [of the control sample] except that the frequency [do not exactly match] and have a shorter bandwidth."[22] The team, who had assumed the presence of carbon black from visual inspection, went on to conclude that the "similarity of the two tests indicates that the design using the carbon black type material produced a poor absorber."[22][23] The Smithsonian Institution has since performed a technical study of the materials used on the prototype and determined that there is "no evidence of carbon black or charcoal", thus invalidating the proposed presence of carbon black to explain the slightly different absorbent property of the prototype wood compared to the control sample of plywood used in the Northrop Grumman testing.[24]

Radar cross section and shape

Radar-testing H.IX V3 reproduction at the San Diego Air and Space Museum

A jet-powered flying wing design such as the Horten Ho 229 has a smaller radar cross-section (RCS) than conventional contemporary twin-engine aircraft because the wings blended into the fuselage and there are no large propeller disks or vertical and horizontal tail surfaces to provide a typical identifiable radar signature.[23][13]

In early 2008, Northrop Grumman paired up television documentary producer Michael Jorgensen and the National Geographic Channel to produce a documentary to determine whether the Ho 229 was the world's first true "stealth" fighter-bomber.[23] Northrop Grumman built a full-size non-flying reproduction of the V3, primarily made out of wood, unlike the original aircraft, which had an extensive steel space-frame to which the wooden skin was bolted. The space-frame for the real aircraft was made from steel tubes up to 160 mm (6.3 in) in diameter, and provided the entire structure for the centre section of the aircraft.[25] After an expenditure of about US$250,000 and 2,500 man-hours, Northrop's Ho 229 reproduction was tested at the company's RCS test range at Tejon, California, US where it was placed on a 15-metre (50 ft) articulating pole and exposed to electromagnetic energy sources from various angles at a distance of 100 m (330 ft), using the same three HF/VHF-boundary area frequencies in the 20–50 MHz range.[23]

Radar simulations showed a hypothetical Ho 229, with the radar characteristics of the mockup, which had neither metal frame nor engines, approaching the English coast from France flying at 885 km/h (550 mph) at 15–30 m (49–98 ft) above the water would have been visible to CH radar at a distance of 80% that of a Bf 109.[26] This implies a frontal RCS of only 40% that of a Bf 109 at the Chain Home frequencies. The US magazine Aviation Week & Space Technology published summaries about stealth technology; some reports indicate the Horten Ho-IX/ Gotha Go-229 returned radar echo just from the annular air entries to turbines, the nose and canopy, and the wing track binding the inner part of turbine intake to cabin.

Variants

Horten Ho 229 V3 prototype at the Smithsonian's Garber restoration facility (National Air and Space Museum)

Rear view of Horten Ho 229 prototype

H.IX V1: First prototype, an unpowered glider, one built and flown (three-view drawing below).[1]
H.IX V2: First powered prototype, one built and flown with twin Junkers Jumo 004B engines.[1]

Gotha developments:

Ho 229 V3: Revised air intakes, engines moved forward to correct longitudinal imbalance. Its nearly completed airframe was captured in production, with two Junkers Jumo 004B jet engines installed in the airframe.
Ho 229 V4: Planned two-seat all-weather fighter, in construction at Friedrichroda, but not much more than the center-section's tubular framework completed.[1]
Ho 229 V5: Planned two-seat all-weather fighter, in construction at Friedrichroda, but not much more than the center-section's tubular framework completed.[1]
Ho 229 V6: Projected definitive single-seat fighter version with different cannon, one captured in production at Ilmenau by US troops.[27]

Horten developments:

H.IXb (also designated V6 and V7 by the Hortens): Projected two-seat trainer or night-fighter; not built.[1]

Ho 229 A-0: Projected expedited production version based on Ho 229 V6; not built.

Specifications (Horten H.IX V2)

Data from Nurflügel,[28] (Ho 229A)The Complete Book of Fighters[29]

General characteristics

Crew: 1
Length: 7.4 m (24 ft 3 in) chord at centre-line
Orthographically diagram

Ho 229A: 7.47 m (24.5 ft)

Wingspan: 16.8 m (55 ft 1 in)

Ho 229A: 16.76 m (55.0 ft)

Height: 1.1 m (3 ft 7 in) cockpit height

Ho 229A: 2.81 m (9 ft 3 in) overall height

Wing area: 52.8 m² (568 sq ft)

Ho 229A: 50.2 m² (540 sq ft)

Aspect ratio: 7.8
Airfoil: 13% thickness
Empty weight: 4,844 kg (10,679 lb)

Ho 229A: 4,600 kg (10,100 lb)

Max takeoff weight: 6,876 kg (15,159 lb)

Ho 229A: 8,100 kg (17,900 lb)

Fuel capacity: 1,700 kg (3,700 lb)
Powerplant: 2 × Junkers Jumo 004B turbojet engine, 8.83 kN (1,990 lbf) thrust each

Performance

Maximum speed: 960 km/h (600 mph, 520 kn)

Ho 229A: 950 km/h (590 mph; 510 kn) / M0.77 at sea level; 977 km/h (607 mph; 528 kn) / M0.92 at 12,000 m (39,000 ft)

Cruise speed: 900 km/h (560 mph, 490 kn)
Never exceed speed: 1,000 km/h (620 mph, 540 kn)
Take-off speed: 150 km/h (93 mph; 81 kn)
Landing speed: 130 km/h (81 mph; 70 kn)
Range: 1,900 km (1,200 mi, 1,000 nmi) maximum
Rate of climb: 22 m/s (4,300 ft/min)
Wing loading: 130 kg/m² (27 lb/sq ft)
Thrust/weight: 0.382

Armament

Guns: Ho 229A: 2x 30 mm (1.181 in) MK 108 cannon

Notes

During the war the British also introduced 200MHz radars for early warning of low flying aircraft (Chain Home Low) and target tracking for ground-controlled interception (AMES Type 7)

References

Citations

Green 1970, p. 247.
Boyne 1994, p. 325.
Dowling, Stephen (2 February 2016). "The Flying Wing Decades Ahead of its Time". BBC News.
Kindy, David (21 October 2020). "Truth Is Stranger Than Fiction With Horten's All-Wing Aircraft Design". Smithsonian.
Metzmacher 2021, p. 199.
LePage 2009, pp. 24-26.
Metzmacher 2021, p. 191, 196.
"Desperate for victory, the Nazis built an aircraft that was all wing. It didn't work". Smithsonian Insider. 5 April 2018. Retrieved 4 May 2018.
LePage 2009, pp. 199, 303-305.
LePage 2009, p. 201.
Maksel, Rebecca (August 2016). "Restoring Germany's Captured 'Bat Wing'"". Air & Space Smithsonian.
LePage 2009, p. 305.
Handwerk, Brian (25 June 2009). "Hitler's Stealth Fighter Re-created". News.nationalgeographic.com. Retrieved 29 July 2012.
"Horten Ho 229 V-2 (Ho IX V 2) der Absturz". DeutscheLuftwaffe.de. Archived from the original on 1 January 2016. Retrieved 21 February 2016.
Brown 2006, p. 119.
"Horten Ho 229 V3 - National Air and Space Museum". airandspace.si.edu. Retrieved 12 April 2023. This object is on display in the World War II Aviation (UHC) at the Steven F. Udvar-Hazy Center in Chantilly, VA
"Horten Ho 229 V3 Technical Study and Conservation". hortenconservation.squarespace.com. Archived from the original on 12 September 2014. Retrieved 11 September 2014.
"National Air and Space Museum Image Detail – Horten H IX V3 Plan – Condition of the Major Metal Components". Smithsonian National Air and Space Museum. Smithsonian Institution. Archived from the original on 1 May 2013. Retrieved 26 May 2013.
"Horten Flying Wing Heading to NASM's Udvar-Hazy Center". warbirdsnews.com. 24 June 2014. Retrieved 28 December 2014.
"Horten Ho 229 V3 | National Air and Space Museum". airandspace.si.edu. Retrieved 12 April 2023. They moved both the wings and the center section into the Boeing Aviation Hangar in September 2017.
"Flying under the Radar: A History of Stealth Planes". National Geographic. 2009. Archived from the original on 27 June 2009. Retrieved 6 November 2010.
Dobrenz, Thomas; Spadoni, Aldo; Jorgensen, Michael (September 2010). "Aviation Archeology of the Horten 229 V3 Aircraft, AIAA 2010-9214". American Institute of Aeronautics and Astronautics. doi:10.2514/6.2010-9214. {{cite journal}}: Cite journal requires |journal= (help)
Myhra 2009, p. 11.
"Is It Stealth?". National Air and Space Museum. Archived from the original on 11 April 2021. Retrieved 24 March 2021.
"How is it Constructed?". Horten IX V3 (Ho 229) Technical Study and Conservation. 12 September 2014. Archived from the original on 12 September 2014. Retrieved 24 March 2021.
National Geographic HD : Stealth Fighter - Hitler's Secret Weapons Recreated| Around 40 minutes in
Dabrowski 1997, .
Horten 1985, pp. 135–151.
Green 1994, pp. 301–302.

Bibliography

Boyne, Walter J (1994). Clash of Wings. New York, US: Simon & Schuster. ISBN 0-684-83915-6.
Brown, Eric (2006). Wings On My Sleeve: The World's Greatest Test Pilot tells his Story. London, UK: Orion Books. ISBN 978-0-297-84565-2.
Dabrowski, H.P. (1997). The Horten Flying Wing in World War II: The History and Development of the HO 229. Schiffer Publishing. ISBN 0-887-40357-3.
Green, William; Swanborough, Gordon (1994). The Complete Book of Fighters. London, UK: Salamander. ISBN 1-85833-777-1.
Green, William (1970). Warplanes of the Third Reich. London, UK: Macdonald and Jane's Publishers Ltd. ISBN 0-356-02382-6.
Horten, Reimar; Selinger, Peter F. (1985). Nurflügel (in German) (1st ed.). Graz, Germany: H. Wieshaupt Verlag. ISBN 978-3-900310-09-7.
Lepage, Jean-Denis G.G. (2009). Aircraft of the Luftwaffe, 1935-1945: An Illustrated Guide. McFarland. ISBN 978-0-7864-5280-4.
Metzmacher, Andreas (2021). Gotha Aircraft: From the London Bomber to the Flying Wing Jet Fighter. Fonthill Media. ISBN 978-1-78155-706-8.
Myhra, David (1997). The Horten Brothers and Their All-wing Aircraft. London, UK: Bushwood Books. ISBN 0-7643-0441-0.
Myhra, David (July 2009). "Northrop Tests Hitler's 'Stealth' Fighter". 19 (6). Aviation History. {{cite journal}}: Cite journal requires |journal= (help)
Shepelev, Andrei; Ottens, Huib (2007). Ho 229, The Spirit of Thuringia: The Horten All-wing jet Fighter. London, UK: Classic Publications. ISBN 978-1-903223-66-6.

External links

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[21] During the war the British also introduced 200MHz radars for early warning of low flying aircraft (Chain Home Low) and target tracking for ground-controlled interception (AMES Type 7)

[WOTR-1] Green 1970, p. 247.

[Boyne_p.325-2] Boyne 1994, p. 325.

[bbc_229-3] Dowling, Stephen (2 February 2016). "The Flying Wing Decades Ahead of its Time". BBC News.

[smith_strange2020-4] Kindy, David (21 October 2020). "Truth Is Stranger Than Fiction With Horten's All-Wing Aircraft Design". Smithsonian.

[Metzmacher_199-5] Metzmacher 2021, p. 199.

[LePage_246-6] LePage 2009, pp. 24-26.

[Metzmacher_1916-7] Metzmacher 2021, p. 191, 196.

[8] "Desperate for victory, the Nazis built an aircraft that was all wing. It didn't work". Smithsonian Insider. 5 April 2018. Retrieved 4 May 2018.

[LePage_199303-9] LePage 2009, pp. 199, 303-305.

[LePage_201-10] LePage 2009, p. 201.

[airspace_2016-11] Maksel, Rebecca (August 2016). "Restoring Germany's Captured 'Bat Wing'"". Air & Space Smithsonian.

[LePage_305-12] LePage 2009, p. 305.

[ng-13] Handwerk, Brian (25 June 2009). "Hitler's Stealth Fighter Re-created". News.nationalgeographic.com. Retrieved 29 July 2012.

[14] "Horten Ho 229 V-2 (Ho IX V 2) der Absturz". DeutscheLuftwaffe.de. Archived from the original on 1 January 2016. Retrieved 21 February 2016.

[15] Brown 2006, p. 119.

[16] "Horten Ho 229 V3 - National Air and Space Museum". airandspace.si.edu. Retrieved 12 April 2023. This object is on display in the World War II Aviation (UHC) at the Steven F. Udvar-Hazy Center in Chantilly, VA

[Horten_Conservation_Website-17] "Horten Ho 229 V3 Technical Study and Conservation". hortenconservation.squarespace.com. Archived from the original on 12 September 2014. Retrieved 11 September 2014.

[18] "National Air and Space Museum Image Detail – Horten H IX V3 Plan – Condition of the Major Metal Components". Smithsonian National Air and Space Museum. Smithsonian Institution. Archived from the original on 1 May 2013. Retrieved 26 May 2013.

[19] "Horten Flying Wing Heading to NASM's Udvar-Hazy Center". warbirdsnews.com. 24 June 2014. Retrieved 28 December 2014.

[20] "Horten Ho 229 V3 | National Air and Space Museum". airandspace.si.edu. Retrieved 12 April 2023. They moved both the wings and the center section into the Boeing Aviation Hangar in September 2017.

[natgeo_2009-22] "Flying under the Radar: A History of Stealth Planes". National Geographic. 2009. Archived from the original on 27 June 2009. Retrieved 6 November 2010.

[arc.aiaa.org-23] Dobrenz, Thomas; Spadoni, Aldo; Jorgensen, Michael (September 2010). "Aviation Archeology of the Horten 229 V3 Aircraft, AIAA 2010-9214". American Institute of Aeronautics and Astronautics. doi:10.2514/6.2010-9214. {{cite journal}}: Cite journal requires |journal= (help)

[Myhra_p._11-24] Myhra 2009, p. 11.

[25] "Is It Stealth?". National Air and Space Museum. Archived from the original on 11 April 2021. Retrieved 24 March 2021.

[26] "How is it Constructed?". Horten IX V3 (Ho 229) Technical Study and Conservation. 12 September 2014. Archived from the original on 12 September 2014. Retrieved 24 March 2021.

[27] National Geographic HD : Stealth Fighter - Hitler's Secret Weapons Recreated| Around 40 minutes in

[28] Dabrowski 1997, .

[Horten-29] Horten 1985, pp. 135–151.

[CBoF-30] Green 1994, pp. 301–302.

Reich Air Ministry (RLM) aircraft designations (list)
1 to 100	8-1¹ Fi 2 8-3¹ 8-4¹ Fi 5 DFS 6 8-7¹ Gö 8 Gö 9 Do 10 Do 11/Wn 11 8-12⁴/Do 12 Do 13 Do 14 Do 15 Do 16/Wn 16 Do 17 Do 18 Do 19 Do 20 8-21¹ Do 22 Do 23 Do 24 Do 25³/Kl 25 Do 26/Kl 26 8-27/Do 27³/Kl 27⁵ 8-28¹ 8-29/Do 29 Fw 30 Kl 31 Kl 32 Ju 33 Ju 34 Kl 35 Kl 36 He 37³ He 38/Ju 38 DFS 39 BV 40/DFS 40 He 41³ Fw 42/He 42 Fw 43 Fw 44 He 45 He 46/Ju 46 Fw 47/He 47 Ju 48 He 49/Ju 49 He 50/Ju 50 He 51 He 52/Ju 52 Ju 53 DFS 54/NR 54 Fw 55/NR 55 Fw 56 8-57⁴/Fw 57 Fw 58/He 58 He 59 He 60/Ju 60 Fa 61/Fw 61/He 61 Fw 62/He 62 8-63⁴/He 63 Ar 64/He 64 Ar 65/He 65 Ar 66/He 66 Ar 67 Ar 68 Ar 69 He 70 8-71⁴/He 71 He 72 He 73³ He 74 Al 75 Ar 76/FZG 76⁶ Ar 77 Ar 78³ Ar 79 Ar 80 Ar 81 8-82⁴ 8-83¹ Al 84 Ju 85 Ju 86 Ju 87 Ju 88 Ju 89 Ju 90 Ju 91³ Ju 92 Ju 93³ Ju 94³ Ar 95 Ar 96 Fi 97 Fi 98 Fi 99 Fi 100³/He 100
101 to 200	Al 101 Al 102 Al 103/Fi 103 R Fh 104 Kl 105 Kl 106 Kl 107 Bf 108 Bf 109/Bf 109R⁶ Bf 110 He 111/He 111U⁶ He 112 He 113⁶ He 114 He 115 He 116 He 117³/Hs 117 He 118 He 119 He 120 Hs 121 Hs 122 Hs 123 Hs 124 Hs 125 Hs 126 Hs 127 Hs 128 Hs 129 Hs 130 Bü 131 Bü 132³/Hs 132 Bü 133 Bü 134 Ha 135 Ha 136/Hü 136 Ha 137 BV 138 Ha 139 Ha 140 BV 141 BV 142 BV 143 BV 144 Go 145 Go 146 Go 147/Ju 147 Go 148³ Go 149 Go 150 Kl 151 Kl 152/Ta 152 Kl 153³/Ta 153 Kl 154³/Ta 154 BV 155/Kl 155³/Me 155 Fi 156 Fi 157 Fi 158 Fw 159 Ju 160 Bf 161 Bf 162/He 162 Bf 163/Li 163/Me 163 Me 164/MeC 164 Bf 165 Fi 166/FK 166 Fi 167 Fi 168 Fi 169³ He 170 He 171³ He 172 He 173³ He 174³ 8-175⁴ He 176 He 177 He 178 He 179⁵ Bü 180/He 180 Bü 181 Bü 182 Bü 183³/Ta 183 Fl 184 Fl 185 Fw 186/Ju 186 Fw 187/Ju 187² Fw 188³/Ju 188 Fw 189 Fw 190 Fw 191 Ao 192 Ao 193³/DFS 193 DFS 194/Me 194 Ar 195 Ar 196 Ar 197 Ar 198 Ar 199 Do 200^4,6/Fw 200
201 to 300	Si 201 Si 202 DFS 203 Si 204 8-205¹ Fw 206 8-207¹ Me 208 Me 209 (I)/Me 209 (II) Me 210 Hü 211 8-212⁴/Do 212 8-213¹ Do 214 Do 215 Do 216 Do 217/Hs 217 Do 218³ He 219 He 220 Do 221³ BV 222 Fa 223 Fa 224 Ao 225/Fa 225 BV 226/Ho 226 FGP 227 DFS 228 Go 229/Ho 229 8-230/DFS 230 Ar 231 Ar 232 Ar 233 Ar 234 Do 235⁵ Fa 236³ BV 237 BV 238 8-239¹ Ar 240 Go 241 Go 242 Me 243³ Go 244 Go 245³ BV 246 8-247¹ Ju 248 BV 250/Ho 250 Ho 251 Ho 252 Ju 252 Fi 253/Ho 253 Ho 254/Ta 254 8-255¹ Fi 256 SK 257 8-258¹ Fw 259 8-260¹ Me 261/Me 261w Me 262 Me 263 (1941)/Me 263 (1942)/Me 263 (1945) Me 264 Fl 265/Me 265 Fa 266/Go 266³ Ho 267 Ju 268 Fa 269 He 270 We 271 He 272³ He 273³ He 274 He 275⁵ He 276³ He 277 He 278 He 279³ He 280 He 281³ Fl 282 Fa 283 Fa 284 Fl 285 Ju 286 Ju 287 Do 288^4,6/Ju 288 Ju 289³ Ju 290 Hs 291 As 292/Hs 292³ Hs 293 Hs 294 Hs 295 Ar 296/Hs 296 Hs 297 Hs 298 Ju 299³ Fw 300
301 to 349	DFS 301 8-302¹ 8-303¹ 8-304¹ 8-305¹ 8-306¹ 8-307¹ 8-308¹ Me 309 Zwilling Me 310 8-311¹ 8-312¹ 8-313⁴ 8-314¹ Hs 315 8-316¹ Do 317 Do 318 He 319 Me 320³ Me 321 Ju 322 Me 323/ZMe 323 8-324¹ Fa 325/Fw 325³ 8-326¹ Me 327 Me 328 Me 329 Fa 330 DFS 331 DFS 332 Fi 333 Ar 334³/Me 334 Do 335 Fa 336 Ju 337³ 8-338¹ Fl 339 Ar 340 8-341 WNF 342 He 343 Rk 344/So 344⁵ Go 345 DFS 346 Rk 347 8-348¹ Ba 349
Post-349 (non-sequential)	Ju 352 Fi 356/Ju 356 Me 362 Me 364² Me 368³ Ju 388 Ju 390 Fw 391 Ar 393³ Ar 396 Ta 400 Me 409 Me 410 Do 417 He 419 ZMe 423 Ar 430/Ka 430 Ar 432 Do 435 Ar 440 8-445⁴ DFS 446 Ju 452 Me 462² DFS 468 Ju 488 Fw 491 He 500 Me 509 Me 510 He 519 8-520⁴ ZSO 523 Ar 532 8-534⁴ Do 535/He 535 Me 600² Me 609 Ar 632 Do 635/He 635/Ju 635
¹ Not assigned ² Unofficial/proposed ³ Assigned, but not used before RLM was dissolved ⁴ Assigned to captured aircraft ⁵ Unconfirmed ⁶ Propaganda/cover designation Note: Official RLM designations had the prefix "8-", but this was usually dropped and replaced with the manufacturer's prefix.