The main regulating unit controls and meters the flow of C-Stoff and T-Stoff propellants, making sure that the rate of flow of one propellant bears a specified relationship to the rate of flow of the other. These functions are carried out by a unit divided into three main sections, the shut-off valve, the C-Stoff rotary control valve and the pressure balance valves.

The unit itself is a compact, complex casting, closely machined. The body castings are of aluminium, with most pistons, push rods and similar moving parts being made from hardened steel. Bushes, piston liners etc., are made from brass, except where they come into contact with T-Stoff, where they are made from hardened steel - brass having a catalytic effect on the T-Stoff.

Viewed from the outside, the regulating unit is composed of three aluminium castings. One for the C-Stoff side of the unit, one for the T-Stoff side and a spacing piece to separate the two sides; to maintain a respectful distance between the two propellants.

Shut-Off Valves

Liquid propellants leaving the pumps enter the regulating unit at two high pressure shut-off cocks. When closed, these prevent any T-Stoff or C-Stoff from reaching the combustion chamber when the motor is running at idling speed.

Both valves are poppet type, spring loaded onto hardened steel seats, shrunk and pressed into the aluminium casting. A push rod on each is arranged to drive the valves open together, so that the flow of liquids through the system is co-ordinated.

An aluminium piston, sealed by a synthetic rubber sealing disc on its top surface, is fixed to the push rod and moves along a cylinder machined in the body of the valve. In order for the liquids to flow, C-Stoff at pressure is admitted to the operating cylinder, forcing the piston to the bottom of its stroke, pushing back the valves against their springs.

When pressure on the piston is released, the valves are forced back onto their seats by their respective springs. As a safety feature, the push rod is cut, near the T-Stoff poppet valve. This is so that if the T-Stoff valve fails to close, it will not stop the C-Stoff valve from closing on its own.

T-Stoff is supplied to the burners in a pressure balance arrangement, which ensures that the delivery pressure of T-Stoff is the same as the pressure at the outlet ports of the C-Stoff rotary control valve.

On the C-Stoff side of the pressure balance valve, three hardened steel pistons slide in brass liners. Push rods connect these to three horizontally opposed pistons which comprise the T-Stoff. In each T-Stoff piston are cut circumferential holes, which have corresponding holes in the cylinder liner.

When the T-Stoff shut off valve is opened, peroxide passes into the jacket surrounding the T-Stoff cylinders, but the spring fitted in each cylinder keeps it shut, closing the ports in the cylinder walls against the flow of T-Stoff.

As the C-Stoff rotary control valve is opened, pressure builds up in the first stage delivery line and this pressure is channelled to the head of the C-Stoff servo piston, moving it along its cylinder. The push rod transmits this movement to the corresponding T-Stoff piston which is opened against the pressure of the spring, the peroxide then flowing through to the burners by means of an outlet pipe connected to the cylinder head. As the rotary control valve is opened progressively, the second and third stage pistons come into play in the same manner as the first.

So there is no delay in the build up of T-Stoff pressure at the combustion chamber burners when the throttle is opened, a small leakage is allowed past the T-Stoff pistons to prime the T-Stoff delivery lines. This is acheived by filing a small "flat" on the curved surface of the piston so that it forms a lead-in to the circumferential delivery ports.

The ends of the cylinders are sealed with synthetic rubber seals, but should any propellant leak occur, there is a large air gap between the C-Stoff and T-Stoff sections of the valve, and so propellant is spilled to atmosphere and does not come into contact with the opposite propellant. Any propellant leakage is collected in a chamber on either side of the valve. On the T-Stoff side this is drained away into the turbine steam exhaust pipe, and on the C-Stoff, it is fed into the inlet for the C-Stoff pump.

Web Master Shamus Reddin