RAF Museum, Cosford
HWK 109-509.C   Wkr.Nr. None

This motor has been on display at Cosford for a number of years. It is obviously a Walter motor with auxilliary combustion chamber, mounted below the main combustion chamber.

The absence of the girder frame, the fact that the fuel control valve unit is arranged "horizontally", not vertically and the completely different layout of the C-Stoff and T-Stoff pipes leads to the conclusion that this is a "C" series motor.

The lack of a well-defined motor thrust plate with the mounting bolts being towards the very front of the unit, with almost all of the component parts of the motor aft of the mounting, defines the "C Series". In comparison, for the "A" and "B" Series motors, the thrust plate divides the motor into a "fore and aft" configuration, the thrust tube and combustion chamber being aft and the main motor components being forward of the fuselage mounting.

There is no discernable manufacturer's plate (nor an obvious place where it should be), but this is certainly the only "C" Series motor so far confirmed in existance.

In the coloured views which follow,it can be seen that sections of the motor have been colour coded for function. This painting is comparatively new, and there are several places where the painting has not been dilligently carried out and paint has either run when wet, or not been applied to inaccessible surfaces. The motor was probably painted whilst fully assembled.

The reasons for the painting are not known, but are possibly for instructional purposes; possibly to conserve the motor; or to make the display more accessible or interesting to museum visitors.

Known History.

At the time of writing, no documentation for this particular exhibit has been confirmed. Post capitulation reports show that at Walterwerke in Kiel, teams of British intelligence officers ran an HWk 109-509.C on a regular basis. At the factory's close, a large amount of material was brought to Britain, including a number of captured projects. A Walter 109-509.C motor was photographed extensively by the RAE, and displayed in the Foreign Aircraft Exhibition in Autumn 1945.

From 1947, the RPE ("Rocket Projectile Establishment") at Westcott in Buckinghamshire, carried a collection of captured rocket motors in their Aircraftsman Hall "museum", which was almost certainly the preserved residue of the RAE's investigative work on German rockets after the war. No paperwork has been unearthed as yet, but photographs exist showing an HWK 109.509.C motor at the RPE England in 1972, before its closure. The vast majority of the survivors from this collection were sent to the RAF Museum and used as the core exhibits to form the Missile Collection at the RAF Museum in Cosford. With no other motor of this type having been identified, it is possibly safe to say that the example in Cosford can trace its history at least back to the RAE.

The following photographs were taken in 1999, at RAF Museum Cosford's Missile Collection.

Description.

This motor is a well preserved example, and quite possibly unique.

All photographs © Shamus Reddin

This view, angled toward the fuel control section, shows the main part of the motor. The horizontally laid, silver unit towards the left is the main fuel flow and pressure equalising unit, connected to which is the silver T-Stoff feed pipe arising from the main fuel pump. First, second and third stage propellant delivery pipes for the main combustion unit are shown in red.

Viewed from the forward part of the motor looking aft, the fuel pump dominates the lower half of the motor. The T-Stoff pump to the right with its bifurcated output. On the left the C-Stoff pump - black pipe. The three closely grouped T-Stoff pipes from the three-stage output, and on the left the corresponding three C-Stoff pipes (each of a different diameter) all painted red lead out down the centre of the main thrust tube.

Just visible on the left, is the curving silver steam pipe which delivers the output steam to drive the turbine of the fuel pump.

An additonal view of the motor control mechanism, the turbine speed control visible in the middle of the photograph.

In this view, looking down onto the top of the motor, is visible the yellow-painted link and control rod between the fuel control valve at the top of the shot and the T-Stoff header tank and turbine speed control just out of frame to the lower right of the picture.

The black pipe at the very top of the picture leads C-Stoff out to the combustion chamber for cooling, the return flow entering the fuel filter from the right.

The fuel flow control valve to the top left of the picture shows the three stage C-Stoff output. Also from this angle the entire route of the T-Stoff outlet from the pump, around and to the inlet side (right here) of the flow control and pressure equalising unit.

The same unit, seen from a different angle, with the fuel flow control valve. This motor has been painted so that the route of the fluid flowing from the regulating units to the combustion chambers is shown in red. But the T-Stoff pipes can be distinguished from the C-Stoff circuit by virtue of the larger diameter pipes.

The silver pipe curving in around the bottom of the picture is the output of the steam generator on its way to the turbine of the main fuel pump.

In this view the black pipes show that part of the C-Stoff flow from the fuel pump, through the regulating valve, outbound to the cooling jacket of the combustion chamber (the top, curved pipe), and then back into the C-Stoff fuel filter; the black pipe on the left of shot.

The first branch on the C-Stoff fuel pipe on the right (just in shot on the bottom right) is the C-Stoff fuel feed into the fuel flow and pressure equalising unit which serves the auxilliary combustion chamber. The auxilliary cruising combustion chamber has a C-Stoff outflow for its own cooling jacket, but there is no return flow pipe.

This close-up of the motor illustrates the principle differences of the "C" unit. There is no box frame, the prominent accessories gearbox unit is missing, the steam generator is "inverted" and served by a T-Stoff header tank and the fuel flow control unit is lying horizontally on its back.

In this view the main elements of the main rocket motor are very clearly shown. From the bottom left, there is the main pumping unit. Following in an anti-clockwise direction, the prominent inverted steam generator is fed directly from a T-Stoff header tank. At the top left of the motor we can see the T-Stoff side of the fuel flow equalising unit, with the silver T-Stoff inlet pipe. The three stage delivery system is shown as the set of red pipes.

In the centre is the vertical turbine speed control unit. Linking this to other elements of the engine control system are the yellow coloured control rods.

On this "C" motor there is an additional unit below and to the right of the turbine speed control, the fuel flow and pressure euqlaising unit for the auxilliary combustion chamber - with a silver T-Stoff inlet pipe and a blue-coloured outlet.

As an interesting aside, this is a small piece of an illustration from Spate's book, "Top Secret Bird", which shows the HWK 109-509.C at Cosford before it was painted in all the various colours as shown. Thiss indicates that the motor was painted by staff whilst already at the Cosford Museum.

Photographs © Shamus Reddin

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