Editing Horten Ho 229 (section)

===Testing and evaluation===
[[File:Horten H IV.A ‘LA+AC’ (N79289) (28256973101).jpg|thumb|Horten IV glider (hanging, top)]]

The first prototype H.IX V1, an unpowered glider with fixed [[tricycle landing gear]], was first flown on 1 March 1944. Flight results were favorable, but there was an accident when the pilot attempted to land without first retracting a test instrument. Following the transference of design responsibility from the Horten brothers to Gothaer Waggonfabrik, the company's design team implemented several changes, including adding a simple ejection seat, substantially redesigned the undercarriage to enable a higher gross weight, changes to the engine intakes, and they added ducting to air-cool the jet engine's outer casing to prevent damage to adjacent wood.<ref name="WOTR" />

The H.IX V1 was followed in December 1944 by the Junkers Jumo 004-powered second prototype H.IX V2. The BMW 003 engine was preferred but was not available. Göring believed in the design and ordered a production series of 40 aircraft from Gothaer Waggonfabrik with the [[RLM aircraft designation system|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]].<ref name = "bbc 229"/> 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 [[Flight test|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. After about 45 minutes in the air, at an altitude of around 800 m, one of the  engines 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.<ref name="ng">{{cite web |url = http://news.nationalgeographic.com/news/2009/06/090625-hitlers-stealth-fighter-plane.html |archive-url = https://web.archive.org/web/20090627211330/http://news.nationalgeographic.com/news/2009/06/090625-hitlers-stealth-fighter-plane.html |url-status = dead |archive-date = June 27, 2009 |title = Hitler's Stealth Fighter Re-created |first = Brian |last = Handwerk |work = News.nationalgeographic.com |date = 25 June 2009 |access-date = 29 July 2012}}</ref> Ziller made a series of four complete turns at 20° angle of bank. He did not use his radio or eject, and may already have been unconscious from the fumes from the burning engine.<ref name = "smith strange2020"/> It crashed just outside the airfield boundary and Ziller later died from his injuries while the aircraft was destroyed.<ref name="ng" /><ref>{{cite web |url = http://www.deutscheluftwaffe.de/Flugzeuge/Projekte/Ho%20IX-V2/Flugunfall.htm |title = Horten Ho 229 V-2 (Ho IX V 2) der Absturz |archive-url = https://web.archive.org/web/20160101153341/http://www.deutscheluftwaffe.de/Flugzeuge/Projekte/Ho%20IX-V2/Flugunfall.htm |archive-date = 1 January 2016 |publisher = DeutscheLuftwaffe.de |access-date = 21 February 2016}}</ref>

[[File:HortenHo229 unloading.jpg|thumb|Unloading of the captured Horten Ho 229 V3 in the [[United States]].]]

Despite this, the project continued. 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 the accelerated production of inexpensive "[[Wunderwaffe|wonder weapons]]". The prototype workshop was moved to the Gothaer Waggonfabrik (Gotha) in [[Friedrichroda]], western [[Thuringia]]. The same month, work was started on the third prototype, the Ho 229 V3.

The V3 was larger than previous prototypes, the shape being modified in various areas,{{fact|date=February 2024}} and it was meant to be a template for the pre-production series Ho 229 A-0 [[day fighter]]s, of which 20 had been ordered. The V3 was to be powered by two Jumo 004C engines, each with 10% greater thrust than the earlier Jumo 004B engine used for the Me 262A and Ar 234B, and had two [[MK 108 cannon|MK 108]] {{cvt|30|mm}} cannons in the wing roots. Work had also started on the two-seat V4 and night-fighter V5 prototypes, the V6 armament test prototype, and the V7 two-seat trainer.

In April 1945, George Patton’s Third Army found four Horten prototypes, the Ho 229s and a Horten glider. Of three Ho 229s, the V3 was nearest to completion, and was shipped to the United States for evaluation.<ref name = "airspace 2016">{{cite web |url = https://www.smithsonianmag.com/air-space-magazine/horten-flying-wing-180960066/ |publisher = Air & Space Smithsonian |title = Restoring Germany's Captured 'Bat Wing' |first = Rebecca |last = Maksel |date = August 2016}}</ref> The Ho 229 spent a brief time at [[RAE Farnborough]] in the UK and during this time installing British jet engines was considered, but the mountings were incompatible with the larger diameter British turbojets.<ref>[[Eric Brown (pilot)|Brown]] 2006, p. 119.</ref> It is uncertain if the aircraft's original Junkers engines were ever run, although the American evaluation team at one point intended to fly it.<ref name = "airspace 2016"/>