The RLM agreed to lend a large field about 70 kilometres east of Berlin, listed as a reserve airfield in the event of war. This was Neuhardenberg, which had no buildings or facilities. A number of marquees were erected to house the aircraft. In the spring of 1937 the Kummersdorf Club transferred to Neuhardenberg and continued the standing trials with the He 112 fuselage.
Erich Warsitz: "In parallel with the von Braun rocket motor aboard an He 112, a lot more was being done: the RLM had suddenly acquired an interest in so-called rocket boosters fitted for the sake of simplicity below the wings of a heavily loaded bomber (Heinkel He 111) to cut down the length of runway needed for take-off from small aerodromes and airfields. Once in the air the spent booster casings would be dropped by parachute for re-use. The firm of Walter at Kiel handled this development."
Walter had also been commissioned by the RLM to build a rocket engine for the He 112, so there were two different new rocket motor designs at Neuhardenberg for a long period, and there now began a very close cooperation with the Walter firm. The initial flight trials now began.
The first He 112 flight using the auxiliary rocket motor fell short of hopes and expectations, but was successful insofar as it proved to official circles that an aircraft could be flown satisfactorily with a back-thrust system through the rear. The subsequent flights at Neuhardenberg with the He 112 used the Walter rocket instead of von Braun's. It was more reliable, simpler to operate and the dangers to pilot and machine were less. After conclusion of the He 112 tests using both rocket motors, and the He 111 rocket booster trials, the marquees at Neuhardenberg were dismantled at the end of 1937. This coincided with the construction of Peenemünde.