The motor pictured above is quite clearly different from all the standard 109-509.A series motors, having an additional, smaller combustion chamber anchored below the main. However, it is equally "clearly" based on an HWK 109-509.A-1 - aside from the extra combustion chamber, this picture shows few differences from a standard "A-1 Series".

This picture was taken at Walterwerke Kiel following the capture of the plant by 30 Assault Unit, Royal Marines in May 1945. The second auxilliary combustion chamber was a cruising chamber, added by the Walter design team in an attempt to improve the endurance of their motor. What is shown here is an HWK 109-509.B which was a test bed for developing the technology which was to lead to the Walter 109-509.C, fully functioning second-generation aircraft rocket motor.

The picture shows the additional combustion chamber, slung beneath the standard combustion chamber. It also shows two silver pipe runs which come from beneath the thrust plate and along the underside of the thrust tube, which carry the propellants to the injectors in the combustion chamber.

Main Features

• Single unit box-frame design
• Auxilliary "cruising" combustion chamber
• Second chamber fuel control system
• Standard fuel flow regulator
• A-1 Series electrical starter
• No steam ejectors

The evidence that this motor is based on a production series HWK 109-509.A-1 is shown in this view of the same motor as above. The electrical starter system is visible, and you can also make out the standard fuel flow and pressure regulating unit.

The difference, is that the T-Stoff fuel delivery pipe is a very short pipe following a much straighter course to the bottom of the fuel regulator, than on the HWK 109-509.A-1. Then there is the additional regulator, visible to the right of the T-Stoff pipe, and above the electric starter.

We know that the two propellants must be mixed in the correct proportions, and this second unit is a scaled version of the main regulating and pressure balancing unit. (See preserved motor below). There must also be a control from the pilot's throttle quadrant - which should run through the airframe to the starboard side of the motor.

The HWK 109-509.B was fitted into a modified Komet airframe and test flown on a number of proving test flights - not all of them without incident. These are illustrated in the following page.

Preserved Motor

There is a surviving HWK 109-509.B motor, in the USAF Museum in Dayton Ohio. Although it has resided in public view for a number of years, pictures of it are rare. The lighting in the museum is dim, and does not lend itself to clear pictures.

For some time, the only pictures I had were courtesy of Bruce Grinstead. However, following a visit to Dayton, I can now identify this unit as 109-509.B "V3". It is known that two motors were fitted to Komet airframes (presumably "V1" and "V2"). As the above photographs were quite possibly taken at Kiel, there is a strong possibility that they show the factory's third test unit, the same motor as now resides in the US. The page dedicated to this motor, discusses the method of operation.

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