TYPE: Interceptor, fighter. Project.

ACCOMMODATION: Pilot only

POWER PLANT: One Kronach-Lorin coal burning ramjet, power output unknown

PERFORMANCE: 650 mph (estimated)

COMMENT: The Lippisch Li P.13b was a follow-on design from the Lippisch Li P.13a, and was also a ramjet fighter. Designed in December 1944, it featured Lippisch’s favorite wing plan, a delta design (sweepback was 60 degrees) with downturned wingtips. A double fin and rudder was chosen to provide steady flight, and the cockpit was moved forward for better pilot’s visibility, ahead of the delta wing’s apex. On each side of the cockpit on the wing’s leading edge were the air intakes which fed the ramjet. For take-off a liquid-fuel rocket driven trolley was used; additional rockets were necessary to accelerate the aircraft to speed for operating of ramjets. The main landing gear was a retractable landing skid, and the rear rested on the reinforced downturned wingtips. No armament was planned at this stage. Because of the fuel shortage in Germany at this stage in the war, an ingenious plan to use coal (or paraffin coated lignite dust) for fuel was to be tried. A centrally installed round or hexagonal heat-resistant ceramic combustion chamber was fitted in the interior of the wing, and was fillable from above. No tests were ever carried out with this design or with the unique power source and the project only stayed in stage of concept sketches on the drawing board (Ref.: 16).

TYPE: Interceptor fighter, experimental aircraft

ACCOMMODATION: Pilot only

POWER PLANT: One Heinkel/Hirth HeS 011 turbojet engine, rated at 1.300 kp

PERFORMANCE: 530 mph

COMMENT: End of 1943, the Arado Aircraft Company began work on a series of delta shaped, turbojet powered bombers, to fulfill the request of a “Long Range/High Speed Flying Wing Aircraft”.  In fact, most of the (in total 14) projects, designated Ar E.555-1 to -14, had a flying wing configuration because it  was thought to be the best design to fulfill a requirement of high speed, heavy loading and long-range aviation. Power was delivered by four to six turbojet engines. Due to the design acceptance by the RLM in early 1944, the Arado design team scaled down the projected, six turbojet engines equipped Arado E.555-1 bomber in same layout to design a smaller size fighter version, the Ar E.581-4. It was a single-seat fighter with a deep fuselage, and was powered by the single HeS 011 turbojet engine fed by a divided air intake under the cockpit. The wing was of a delta shape with the twin fins and rudders on the trailing edge, and the landing gear was of tricycle arrangement. Although work on the project was in progress Arado was ordered to cease all work on the  Ar E.581 for concentrating all facility resources on the existing fighter production (Jäger-Notprogramm, Fighter emergency program)  (Ref.: 16).

TYPE: Target defense interceptor. Project.

ACCOMMODATION: Pilot only, in seated position

POWER PLANT: Three Pabst/Lorin ramjets at wingtips, rated at 840 kp thrust each. For starting ramjets Walther 109-500 solid-fuel rockets were fitted to each ramjet, rated at 500 kp for 30 seconds each

PERFORMANCE: 621 mph (estimated)

COMMENT:  This Focke-Wulf Vertical Take-Off and Landing (VTOL) fighter/interceptor project was designed in September 1944, at the same time when the Heinkel Company worked on its VTOL-projects “Lerche” and “Wespe”. But in contrast to the latter two designs the propulsion system of the Focke-Wulf project was radical different. Three untapered wings rotated around the fuselage and had a gradually decreasing pitch towards the wingtips, thus acting like a giant propeller (“Triebflügel”). At the end of each wing was a Pabst ramjet. Since ramjets do not operate at slow speeds, the wing-rotor had to be driven by small Walter rocket engines, fitted to each ramjet pod. When the plane was sitting on its tail in the vertical position, the rotors would have functioned similarly to a helicopter. When flying horizontally, they would function more like a giant propeller. A cruciform empennage at the rear of the fuselage comprised four tail planes, fitted with moving ailerons that would also have functioned as combined rudders and elevators. A single large and sprung wheel in the extreme end of the fuselage provided the main undercarriage. Four small castoring wheels on extensible struts were placed at the end of each tail plane to steady the aircraft on the ground and allow it to be moved. The main and outrigger wheels were covered by streamlined clamshell doors when in flight. When taking off, the rotors would be angled to give lift as with a helicopter or, more accurately, a gyrodyne. Once the aircraft had attained sufficient altitude it could be angled into level flight. This required a slight nose-up pitch to provide some downward thrust as well as primarily forward thrust. Consequently, the four cannons in the forward fuselage would have been angled slightly downward in relation to the center line of the fuselage. The rotors provided the only significant lift in horizontal flight. To land, the aircraft had to slow its speed and pitch the fuselage until the craft was vertical. Power could then be reduced and it would descend until the landing gear rested on the ground. This would have been a tricky and probably dangerous maneuver given that the pilot would be seated facing upward and the ground would be behind his head at this stage. Unlike some other tail sitter aircraft, the pilot’s seat was fixed in the direction for forward flight. The spinning rotor would also obscure rear vision. Although the “Triebflügeljäger” project was not realized, a wind tunnel model was tested up to a speed of Mach 0.9 (Ref.: 17, 18, 23)