Gotha Go 229 / Horten Ho IX
Flying wing fighter
Horten Ho IX
The Gotha Go 229 was the first turbojet-driven warplane of pure flying wing configuration. Although flown for the first time in 1945, the aircraft looks surprisingly modern --- almost like a small version of the Northrop B-2 stealth bomber.
The Go 229 was initially designed by the brothers Reimar and Walter Horten, pioneers in early flying wing aircraft designs. The Horten brothers were attempting to figure out ways to eliminate every sourse of parasitic drag. They believed that the flying wing configuration offered the best way to achieve this feat.
Their flying wing proposals had no fuselage as such, and they looked a lot like the Northrop flying wing designs produced in the USA during the 1940s and later. The chord of the wing center section increased sufficiently to enable pilot and powerplants to be housed entirely within the wing itself without any drastic increase of thickness/chord ratio. There were no vertical surfaces --- lateral and directional control were provided by a set of spoilers.
The Horten brothers' interest in flying wings dates back to the Horten I wooden sailplane of 1931. The brothers produced a number of experimental powered and unpowered flying wings throughout the 1930s. In 1943, they began to envisage a jet fighter flying wing design, designated Ho IX. The Ho IX was to be powered by a pair of BMW 003 turbojets.
The Ho IX was what was later to be known colloquially as a "skunked" project --- it went forward initially without the support (or even the knowledge) of the all-powerful Reichluftfahrtministerium (RLM, the State Ministry of Aviation). Work on a single prototype (designated Ho IX V1) was begun at Gottingen.
The Horten brothers planned that their Ho IX V1 was to undergo an extensive series of gliding tests before any attempt was to be made to install the pair of BMW 003 turbojets. However, in early 1944, RLM became aware of the existence of the Ho IX V1.
The project captured the imagination of Reichsmarschall Hermann Goering who gave it his enthusiastic backing. In addition, intelligence reports from the USA indicated that the Northrop Corporation was thinking along similar lines. The Ho IX project was to move forward to powered flight testing with all deliberate speed.
With official backing now present, the Ho IX project gained momentum. The first gliding trials began in spring of 1944. Gliding tests were highly satisfactory. The planned installation of the BMW 003 turbojet engines in the Ho IX V1 prototype was deemed impractical, and it was decided to install a pair of Jumo 004 engines in the second prototype (Ho IX V2).
The Ho IX V2 was designed for a 7g safe load factor. The center section of the wing housed the engines and the cockpit and was made of conventional welded steel-tube construction. The center section was covered with plywood skinning except in the immediate vicinity of the engine exhausts, where metal was used.
The outer wings were made entirely of wood. The outer wing leading edges were constructed of a special molded wood (wood shavings compressed with resin), but the rest of the wing was covered with plywood. A special coating of lacquer was applied to give a smooth finish to the entire aircraft.
I think that the idea of the lacquer finish was to give an aerodynamically smooth surface rather than to provide any "stealth" characteristics --- that was still many, many years in the future.
Two Jumo 004B turbojets were mounted side-by-side close inboard in the center section. The jet tailpipes protruded above the wing rear surfaces. A tricycle undercarriage was fitted. Lateral and longitudinal control was provided by elevons which, together with plain flaps, occupied the trailing edges of the outer wing panels.
Spoiler flaps extended across most of the wing center section immediately aft of the mainwheel wheels. Directional control was achieved by spoilers located near the wingtips just aft of the main spar.
Glide tests with the Ho IX V1 were sufficiently encouraging that the RLM decided that the Horten design was worthy of production as an operational combat aircraft. In early summer of 1944, the Friedrichsroda facility of the Gothaer Waggonfabrik was given a contract for the production of the design under the designation Go 229.
Control of the adaptation of the design for production was taken away from the Horten brothers, but the brothers continued to work on the testing of their Ho IX prototype.
Gotha immediately began work on the production of the flying wing fighter. The initial production version was to be given the designation Go 229A. The Gotha team found it necessary to introduce some changes in order to adapt the Ho IX for production. They redesigned the cockpit, enlarged the turbojet housings, revised the air intake geometry and modified the undercarriage.
Provision was made for four 30 mm MK 103 or MK 108 cannon mounted immediately outboard of the engines. Hardpoints were to be provided beneath the center section for two 2205-lb bombs or for two 275 Imp gall fuel tanks. A two seat radar-equipped all-weather version (designated Go 229B) was also envisaged.
In the meantime, the Ho IX V2 was transferred in January 1945 to Oranienberg for powered flight testing. Flight tests went quite well. Handling characteristics were much better than expected. A maximum level speed of 497 mph was attained during the tests. Unfortunately, the Ho IX V2 crashed during a landing attempt and was totally destroyed.
Gotha's first production prototype for the Go 229A single-seat fighter-bomber series was given the designation Go 229 V3. V4 and V5 were to be the prototypes for the Go 229B alweather fighter, and V-6 was to be a second A-series prototype with MK 103 cannon in place of MK 108s. V7 was to be a prototype for a two-seat training version.
All through the spring of 1945, work proceeded at Friedrichsroda on these prototypes. However, late in April, the Friedrichsroda plant was finally occupied by American troops and developmenent came to an abrupt end.
At that time, the Go 229 V3 prototype was being prepared for flight testing, and the V4 and V6 prototypes were in final assembly. Component manufacture for the 20 pre-production Go 229A-0 fighter bombers was well advanced, and various component parts were found strewn about the factory.
The Go 229A-0 pre-production fighters were to be powered by a pair of Junkers Jumo 004B-1, -2, or -3 turbojets, 1962 lb. st. each. Estimated maximum speed was 590 mph at sea level and 607 mph at 39,370 feet. Maximum ceiling was to be 52,500 feet (!!! Remember, this was only 1945, folks!). Maximum range was estimated at 1180 miles, and initial climb rate was to be 4330 ft/min. Weights were estimated at 10,140 lb empty, 16,550 lbs. normal loaded.