Take-Off Packs in Service
Walter HWK 109-500 Motor

HWK 109-500 Pack Design
Liquid Rockets or Solid Rockets?


Arguably, one of Walterwerke's most famous developments, the HWK 109-500 rocket assisted take-off pack, or "Starthilfe" ("Take-Off Assister") was, aside from the motor for the Messerschmitt Me.163 interceptor, one of their most successful production motors.

The HWK 109-500 was made in greater numbers than all the other liquid fuelled rocket motors which Walterwerke designed, and saw service in a wide variety of German war theatres.

The problem of heavily laden service aircraft having to operate from less than ideal front line airfields, or the problems of maximising the effectiveness of the fuel load any aircraft can carry, were problems each airforce faced. Propelling the aircraft forward with sufficient power to lift off in a short space, or providing enough motive power in the early stages of the take-off of a heavy aeroplane before the wings could give sufficient lift to enable the fitted propeller motors to take over, were service "holy grails" which many designers have tackled over the years.



[Arado Ar.234 rocket assisted take-off]

For a standard, unmodified, front line aircraft loaded with as many of the the latest armaments as it could carry, an additional power source used just for the take-off, and discarded once the aircraft was airborne, was the answer most airforces settled on. Few more successfully than the Luftwaffe -
and the HWK 109-500 was Walterwerke's option

The Walter HWK 109-500 was a liquid-fuelled rocket motor carried in a streamlined pack, usually underslung beneath the wings of the aircraft.

Able to be manipulated by a small team of aircraft fitters they were used in symmetrical pairs either side of the aircraft centreline, hung on a cradle from attachment points. Fired electrically from the cockpit at the moment of take-off, they provided a ten second burst of extra power to lift the aircraft into the air.

Once the fuel was expended, the packs were jettisoned, and returned to the ground by parachute. Collected from the airfield perimiter by ground crews, they could be serviced and re-used for future take-offs.

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