Authored By Dan Alex (Updated: 4/21/2016):
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.
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.