Solid Fuel Motors.

During the 1950s and 60s, solid fuel rocket motors were developed for a variety of purposes at the Rocket Propulsion Establishment (R.P.E.) at Westcott in Buckinghamshire.

The Superintendent was apparently a keen ornithologist, and so all the different motors were named after birds!

Motors were developed for a variety of different uses. One was for testing 'off the shelf' designs for various specific purposes. Another was directed to the development and production of guided weapons, principally surface to air missiles. A highly successful sounding rocket, Skylark, was also developed, which was fired in the hundreds, and came in a variety of different configurations.

Many such motors were developed: here are some details about three of them.

The Rook

Rook solid fuel motor

The largest solid fuel motor produced at Westcott was the 36" Stonechat, used in the Falstaff vehicle. The next size down was the 17" motor, of which the Rook was a very typical example.

Typically, up to a hundred or so static firings would be made at Westcott to establish the reliability of the motor. A typical thrust/time curve is shown below:

Some test firings would also be carried out with simple test vehicles: here is a frame from a cine film of a Rook firing, which seems to be burning through at the end of the case. A secondary flame can be clearly seen:

Rook solid fuel test flight

illustrations from R.P.E. Technical Note No. 212, June 1962.

"The motor is of 17 inches diameter and 208 inches overall length. It contains a case-bonded charge of 1866 lb of non-aluminized plastic propellant giving a total impulse of 395,000 lb-seconds in 5.6 seconds; the maximum thrust is 72,600lb. The motor has proved capable of withstanding the longitudinal acceleration of 40g imposed during firing; it is currently being employed as the first propulsion stage of the Leopard and Jaguar (Jabiru) supersonic test vehicles."

K. C. Pearson, from R.P.E. Technical Note No. 212.


Gosling soild fuel rocket motor

You can see 2 Gosling boosters in the photo, close to each other. Top and bottom of the missile are the Thor ramjet sustainers.

664 Gosling IV motors were supplied for the Thunderbird, Bloodhound, and Seaslug Mark II missiles.

Gosling IV data:

All up weight 568 lbs.
Length 118.3 inches
Diameter 10 inches
Burning time at 18oC 3.15 seconds
Mean thrust at 18oC 27,800lb.

data from R.P.E. Technical Note No. 216, January 1963.

A word of caution must be added about performance figures. Many variants on a particular motor were produced, filled with different propellants. In some cases this might represent an improved formula, but other versions might be produced where the propellant is slower or quicker burning, depending on the particular application.


Jackdaw solid fuel rocket motor

This rather odd looking motor was developed for flight testing 2/5th scale models of the Blue Steel missile. Blue Steel was to have two liquid fuelled rocket chambers - hence the odd configuration of this motor.

This is a cross section of the motor, and illustrates the 'star shaped' filling. The propellant did not burn from the bottom up, like a firework, but was ignited from the top. The ignitors can be clearly seen in all these drawings. An electric current of a few amps was passed through a wire, which became hot enough to start the material in the ignitor burning. This spread down the centre so that the propellant burns from the inside out. The star shape means that the burning surface stays roughly constant.

More on the Cuckoo motor, used as a second stage for Black Knight.

... back to the rocket motors page or the UK Space page ...