[USAF Museum 109-509.B-1]

Originally supplied with photographs from a Komet fan from North America, Bruce Grinstead, I have now visited the museum personally to see the motor in greater detail.

When the pictures were taken, the motor was displayed alongside a Messerschmitt Me 163 Komet Wkr.Nr.191095, which was then on loan from Canadan National Museum.


Known History.

No data as yet.



This motor has been well preserved, coated with a fairly "standard" preservation paint scheme, of black for the steel parts and silver for the other pipework and castings. This will ensure that the motor lasts well into the future, but it is in contrast to the appearance of original motors which have not been heavily restored.

As a general view, this shows the typical characteristics of a model "B" motor. At first glance the frame shows classic features of a "A-1" model: the accessories gearbox and Bosch electrical starter.

However, a moment's more examination shows quite clearly the second, accessory, "cruising" combustion chamber, suspended beneath the main combustion chamber. Additionally, there are unfamiliar items of pipework, and plumbing visible in the frame.

All photographs © Shamus Reddin
[109-509.B-1 Twin Combustion Chambers]

Looked at from the other side, this view plainly shows two outstanding features. The most obvious is the secondary combustion chamber. The German name for this was the "Marschofen", which translates as "auxilliary" chamber, and its purpose was to supplement the main combustion chamber, by providing a lower output thrust (and hence improved fuel consumption) during level flight.

One can also see the pipe runs taking propellant from the main body of the motor underneath the main thrust tube. These runs are not designed as thrust or load-bearing, as the Marschofen is securely bolted to the main chamber, and angled so to transmit its thrust down the main thrust tube - "Laterne".

[Forward end of Motor]

From this angle, one can see the standard fuel flow/pressure equalising unit on the top of the frame, the C-Stoff filter, the quite normal steam generator and the large accessories gearbox. That this motor has been based on an "off-the-shelf" A-1 motor is quite clear.

A noticeable difference is the much more complex lever system coming from the linkages from the pilot's control, to the bottom of the turbine speed control unit.

The turbine speed control is more complex than a standard unit, as it carries the propellant pressure from the pump not only to the main C-Stoff/T-Stoff regulating unit, but to a secondary unit, in the lower part of the motor, which balances the propellants to be delivered to the Marschofen.

[Forward end of Motor]

In this view, the pressure balance and regulating unit for the main combustion chamber is clearly shown, together with the C-Stoff filter, on top of the motor frame. The Bosch electrical starter at the bottom is also plainly visible.

However, the additional complexity of the cruising chamber needs a further system of regulation, which can just be seen within the main motor body, and this is discussed in the sections below.

[Forward end of Motor]

In this model of motor, the turbine speed control "Druckregler" has been modified with an additional control section, which can be seen as a cylinder extending below the normal limit of a standard speed control. Linked to an additional control lever in the cockpit, this sets the T-Stoff flow into the regulator for the cruising chamber.

There has to be a different, lower, turbopump output, as the auxilliary combustion chamber needs only a small mass flow of propellants, in comparison to the main combustion chamber. The goal for this unit, was to provide airborne thrust, but a much lower propellant consumption, giving a greater range.

[Forward end of Motor] [Forward end of Motor]

The additional control system for the cruising combustion chamber, the "Zusatzregelgerät", is shown in these pictures. Although it is difficult to appreciate the design of this piece of equipment as it is shown in situ, it works in a very similar way to the main propellant flow regulator.

A lever, shown in the third picture, is connected to a lever in the pilot's cockpit. When it is desired to switch to the cruising chamber, the pilot's lever rotates a cylinder which causes C-Stoff to flow through the passages which are then opened up.

[Forward end of Motor]

In common with the main regulator, the auxilliary regulator is split into two distinct halves. To the left here, with the lever and rotating cylinder, is the C-Stoff end. Above is shown the T-Stoff side, with (taking the picture on the left, above) a tapping from the T-Stoff outflow from the turbopump curving around from the left and into the side of the auxilliary regulator. The T-Stoff flow is held back by a pressure spring which, as is the case with the main regulator, is acted upon by a pushrod driven by C-Stoff pressure.

The pushrod is a means of keeping apart the C-Stoff and T-Stoff liquids, so that any leaks do not come into contact. However, when the cylinder is turned, C-Stoff begins to flow, the pressure of which pushes against one end of the rod system. This push lifts the spring-loaded T-Stoff stop-valve away from its seating, and T-Stoff also begins to flow.

The T-Stoff outflow (shown above, as the pipe which comes out on the right and towards the camera before turning back and heading down towards the combustion chamber) goes directly down to the auxilliary combustion chamber where it meets the C-Stoff for combustion.

When the lever is closed, C-Stoff stops flowing. The drop in outflow pressure of this is insufficient to act against the closing pressure of the T-Stoff spring which then shuts off the T-Stoff flow.

[Twin Combustion Chambers]

The purpose of this motor was as a test vehicle for the various elements of a multi-chambered propulsion unit. Here are shown the twin combustion chambers - the main thrust chamber is the larger, upper unit. Slung below, and bolted to brackets welded onto this, is the auxilliary "cruising" chamber. This is smaller, indicating the lower thrust output.

The other indicator to the smaller thrust level, is the smaller number of propellant flow lines - the lower mass flow of propellant will produce a lower specific impulse (thrust).

What is not apparant, is that the C-Stoff flow, the dark pipe here on the right, is used for combustion chamber cooling, but instead of returning to the main motor, is taken directly to the combustion chamber head for injection. The silver coloured pipe, branching into three, is the T-Stoff line.

Also shown in the picture, is the emergency dump valve, to clear the combustion chamber cooling space of C-Stoff if the propellant pressure drops suddenly. Of the two smaller lines at the combustion chamber head, one is a steam line to blow any residual propellant from the combustion space before main combustion flow is initiated, and the second is a pressure line to provide combustion chamber pressure information back to the pilot.

Web Master Shamus Reddin   [SR Logo]
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