The Horten Ho IX (or "Horten Ho 229" - sometimes incorrectly designated the "Gotha Go 229") maintains a certain level of celebrity status in the world of World War 2 military aviation, essentially becoming the first production-worthy form of any aircraft categorized as a true "flying wing" - that is an aircraft not relying on any sort of vertical tail surfaces to achieve flight and maneuverability. Additionally, the Ho IX/Ho 229 was the first to incorporate radar absorbing "stealth" technologies into its frame work - quite the accomplishment in forward thinking for 1944 - and made heavy use of swept-back wings before they became the norm of the jet age. In these ways alone, the Ho IX/Ho 229 was truly a marvel attempt in every way imaginable that a handful of prototypes were constructed to iron out the design. Though a production order was in the works by 1945 though the end of World War 2 saw to it that this machine never contributed to the German war effort in any respect, thus leaving the reader to his/her imagination as to the impact the system would have had in the skies over Europe.



Flying Wings



Flying wing designs had been the focus of man-a-aircraft engineer for some time leading up to World War 2. American Jack Northrop himself was one of the big name pioneers in the realm, working on his own flying wing designs, while the Horten brothers - Reimar and Walter Horten - had been studying the capabilities and possibilities for some time now primarily in the field of unpowered glider flight (a third brother, Wolfram, would later die when his bomber was downed over Dunkirk).



Flying wings featuring a lack of vertical implements theoretically offered some inherent advantages by the deletion of such surfaces thus reducing drag to an extent. The Hortens strongly believed that such structures aboard a planform offered more drawbacks than additions. In a flying wing design, the fuselage was generally integrated into the wing roots for a very streamlined approach adding to effective aerodynamic principles. A larger wing surface area also promoted a better rate-of-climb, a larger fuel load (essentially increasing range) and a larger bomb load. However, the lack of vertical flying surfaces also brought about challenges in controlling such an aircraft - an issue that Northrop dealt with to a high degree in his XB-35 flying wing strategic bomber (finally realized in the modern Northrop B-2 Spirit stealth bomber). Northrop's attempt was in fact a commissioned effort to develop a wing-only design based on pictures received of the Horten early 1930's glider attempts. Such wing-only flight would not be realized until the advent of powerful computers in the modern age that could aid the pilot in flight, keeping the aircraft from entering irrecoverable actions.



Horten Roots



With restrictions set forth by the Treaty of Versailles following World War 1, the German manufacturing capacity for waging war was severely restricted by the victors. As such, government funding that may have been intended for the production of tanks, guns, planes and the like were instead funneled to other "peacetime" ventures within the country. One such venture proved to be the various glider clubs forming across Germany. These clubs allowed Reimar and Walter the chance to forge some tail-less glider design concepts into practice. Essentially, the glider club was another German attempt to skirt the rules of the Versailles Treaty and train young pilots while testing out aircraft designs under a certain level of secrecy. Though never formally trained in aeronautics, the Hortens maintained a love affair with flight and grew into experienced pilots in their own right, this occurring in their critical early years and helping to pave a legacy now forthcoming. Even as teenagers, their first flyable glider was completed in 1933.



The brothers took to developing models in the beginning and then culminated this process with the production of the Ho I sailplane in 1934. The Ho I was a tail-less system with straight wings that, by all accounts, flew quite well. The pilot sat in a prone position within the apex of wing assembly while elevons were utilized for pitch and roll control while brake flaps were integrated to account for yaw. These brake flaps were affixed to the upper and lower sections of the wing leading edge.



Despite this early success, the Horten brothers were destined to get more out of their concept and put forth a newer design approach. They destroying their original Ho I and took to building a more efficient design. The second attempt was appropriately designated as Ho II and featured swept-back leading and trailing edge wings, a prone glazed-over cockpit and instantly set itself apart from the preceding design attempt. Four Ho II prototypes were produced to test out further flying wing concepts and while at least one of these was powered through a single Hirth-brand 80 horsepower engine mounted to the rear of the main body in a "pusher" arrangement. The Ho IIs were tested sometime in 1938, with one such flight occurring at Darmstadt in the capable hands of renowned female test pilot Hanna Reitsch.



Such developments in wartime Germany did not go unnoticed. Ernst Udet, the Director of the Technical Department of the German Air Ministry, found favor in the Horten's work and brought to them more funding for continued development of the perceived plans. The brothers moved into a more permanent environment operating out of Tempelhof Airport and quickly set to work on the Ho III. Like the Ho II before it, the Ho III featured swept-back wings with a retractable undercarriage. The system basically followed much of the same design lines of the Ho II, becoming an enlarged version of the second attempt. The Ho III was also produced in four working prototypes with one fitting an engine. Of note in the powered Ho III was the inclusion of folding propeller blades which could be collapsed in flight to help reduce drag. While being powered, the Ho III was still a glider through and through. The design made use of a wide span swept wing approach with the pilot seated at the center of the forward profile under a forward-opening glazed cockpit with the engine mounted to his rear.



The Ho IV followed the Ho III as two constructed prototype forms but were, from the outset, simply designed to test out theories and effects of high aspect ratio wings. One of these such aircraft was lost in a crash brought about through an irrecoverable spin.



The Ho V was also produced in two working prototypes, the second being of note for its use of plastic in the construction. The Ho Vs were destined to be powered research airframes and nothing more. These prototypes were originally fitted with a two man cockpit with construction running from 1936 into 1938. In 1942, however, the Ho V was modified to a single seat form. Once again turning to a swept-wing appearance, these gliders featured lesser sweepback along the leading edge and a straight trailing edge - effectively more of a "true" delta type shape. Construction of the internal main body frame was of welding steel tubing and space was made to accommodate 2 x Hirth engines of 80 horsepower in a "pusher" set up.



The Ho VI appeared as a "one-off" prototype example following in line with the Horten IV. This flying wing offered up a greater span than others before it but proved too delicate for the rigors of even basic ground operations. The similar Ho VII followed suit but fitted 2 x Argus As 10C engines of 240 horsepower each. A single prototype was constructed of this model and later relocated to Oranienburg in March of 1945. It is believed that the Ho VII was tested there to some extent.



The Ho VIII proved the most ambitious Horten flying wing attempt to date - a six engine, 60-passenger commercial endeavor. Power was to be supplied by no fewer than 6 x BMW 600 horsepower (each) engines fitted into a pusher arrangement. The wingspan of 262.5 feet alone made this flying wing design easily the largest Horten. Range estimations put the Ho VIII at 3,725 miles at speeds hitting over 200 miles per hour. The design would never reach a finished prototype form for the collapse of Nazi Germany by mid-1945 killed the project altogether. It was expected that the working prototype would have been completed by November of that year.



The "Amerika Bomber"



The Ho VIII was later considered for the "Amerika Bomber" project as the Ho XVIII - an attempt at designing and constructing a super-long range bomber capable of hitting industrial targets in America from possibly the Azores. The Hortens submitted their plan after Christmas of 1944 when other proposals from Messerschmitt, Junkers, Heinkel and Focke-Wulf could not meet the range requirement. The Amerika Bomber project, like many other of Hitler's ambitious visionary systems, came to naught by war's end. The Horten brothers were working on the Amerika Bomber while Gotha took to further developments of their flying wing fighter-bomber after model V2.



The Ho XVIII bomber would most likely have fitted an atomic bomb should both projects (the bomber and atom bomb) have advanced in Germany. The XVIII proved to be the Horten brother's final wartime contract, this awarded on March 12th, 1945. Construction of the XVIII began at Kahla near Weimar in April of 1945, under the concrete roof of bomb-proof shelters but was she never completed.



The XVIII A was, much to the dismay of the Horten brothers, accepted into a design-by-committee approach incorporating Messerschmitt and Junkers engineers. Reimar reworked the XVIII into the XVIII B flying wing instead, which was accepted for construction. Armament would have been 2 x MK 108 30mm cannons mounted under the cockpit floor, the cockpit itself seating three personnel. Power would have been supplied via 2 x Henschel He S 011 turbojet engines.



The German War Machine Comes Calling



Hermann Goring, the stout World War 1 ace (22 kills), Blue Max recipient and now Reichsmarshall of the German Luftwaffe, laid out his "3 x 1000 Projekt" requirement envisioning a fast, long-range bomber with a lethal payload capacity. The project name came about as the bomber would have to be capable of 1,000km speed with a range of 1,000km while ferrying a payload of up to 1,000kg (values translated respectively as 2,200lbs, 620 miles and 620 miles-per-hour). Ambitious to say the least, such a bomber would have been a pivotal war addition to the Luftwaffe toolbox. A long range bomber was always on Goring's scope, who saw the American war machine in the United States as a prime target for disrupting the air campaign ravaging Germany's industrial capacities. This particular bomber initiative, however, would be useful in striking at Allied targets throughout England. To get his prize plane, Goring announced no further contracts unless the proposed aircraft design could meet these requirements. Only one change was further added to the requirement, this by the Fighter Division. Their request was for the addition of 2 x 30mm MK 108 cannons for fighter-on-fighter engagements - a move that could take substantially from the aircraft's intended bomber role.



The Horten brothers jumped in with their flying wing concept believing that the only question mark left was in the selection of a capable engine to power their design and make their bomber reach the stated goals. The project was developed as a private venture and the brothers unveiled the Ho IX. The German Air Ministry accepted and required a first flight in a short six-month window.



The Ho IX



The Ho IX was reminiscent of previous Horten offerings though in many ways this could be considered the pinnacle of their previous attempts. The Ho IX served as the only military combat aircraft that the brothers would get close to full scale production. The design was again based on a large surface area wing an integrated fuselage containing armament, engines and cockpit. The center body's internal workings were again made of welded steel tubing. The wings featured single wooden spars and covered encased with carbon-covered plywood sections held together by a specialized mixture of charcoal and sawdust. The airframe was designed to withstand loads of up to 7g. The undercarriage was wholly retractable and of a tricycle arrangement with the nosewheel borrowed from a Heinkel He 177 Greif (Griffin) long-range heavy bomber. The nosewheel retracted rearwards under the cockpit floor whilst the two main landing gears recessed inwards towards the fuselage just under the wingroots. The single-seat cockpit (complete with a primitive ejection seat system) offered up exceptional views up, over and around the upper wing section but, as one can surmise, other views were generally restricted. The originally selected powerplant proved to be the BMW 003A-1 series turbojets straddling either side of the cockpit, though these were not yet available at the time and replaced with Junkers Jumo 004 series engines. With the lack of vertical tail surfaces, the Ho IX made use of elevons with two spoilers differing in lengths located along the wings. The dual-spoiler configuration allowed for an improved control action to replace the action brought about by a more conventional rudder arrangement or single wing-mounted spoiler.