One of the gliders was used to test the aerodynamics of a prototype World War II Horten jet fighter-bomber.

The Horten brothers' first glider, the H.I, was a true flying wing without any vertical surfaces or fuselage which had flown for seven hours at the 1934 Rhön competition on the Wasserkuppe.

With improved yaw control it flew much better, though a test report from Hanna Reitsch made it clear that more work was required.

[4] The seat in the Habicht was strongly reclined and positioned the pilot entirely within the 700 mm (28 in) maximum thickness of the central wing profile.

[1] It was soon flying as a motorglider, designated H.IIM[2]: Section 3  powered by a pusher configuration Hirth HM 60R air-cooled, inverted, four cylinder, inline engine, mounted on top of the wing.

[3]: p.51  Their performance there were not outstanding as their wing loading was too low to reach the speeds necessary for rapid cross country flights between thermals.

[1] The third Horten H.IIL was test flown in November 1938 by Hanna Reitsch, who reported that whilst comfort was "not exceptional", the "view is bad" (even with the new canopy), entry and exit were "only possible for athletes" and that the undercarriage retraction lever could only be operated by pilots with longer arms than hers.

Witnesses described how the canopy detached during a high-speed dive in aerobatics practice, hitting pilot Kurt Hiekmann.

[1] It was much involved in the 1944 development of the Horten IX twin-jet fighter-bomber; most notably it was flown as a "wind-tunnel substitute" for the H.IX V-6, with its extended, pointed nose, dummy air-intakes and exhausts, and twin small fins.