Wilmot Mansour (Jetex) Wren

wren01

These iconic profile models, designed by Mike Ingram were first produced by Wilmot Mansour in the mid 1950's.

Please indicate below if you require a version for
L1 (smaller) or L2 (high power).

Wilmot Mansour (Jetex) Wren
£15.00

Operating the Jetex 50


50-original-half
- drawings by Carlo Godel

 


Below, we reprint the operating instructions provided with the original Jetex 50 motor.

  1. Be sure the engine is firmly held in its mounting bracket. and that the bracket is securely attached to the vehicle.
  2. Pinch off sufficient lead-in wick and insert through the jet nozzle, so that the inner end contacts the wick coiled on top of the fuel pellet.
  3. Light the wick.
  4. Igniting the fuel pellet will usually blow the wick core out of the nozzle. If it sticks. immediately pluck it free. Wet your thumb and finger before lighting the wick, so that you will be ready to do this if necessary.
  5. Wait 2 or 3 seconds until a strong steady hissing indicates that thrust has been developed.
  6. Release the model.

 

Acknowledgements

Illustration sources:

- Original drawings by Carlo Godel

 

Micro rocket power for the third millenium

With the new millenium came the Rapier range of motors, manufactured in the Czech Republic. Unlike the reloadable Jetex motors, these are strictly one-shot items. Essentially, they consist of a cardboard tube filled with propellant and plugged with a ceramic end cap with a hole.

Currently, Rapiers are available in three power ratings: L-1, L-2 and L-2HP. The earlier L-3 series has now been phased out of production, having been superseded by the L-2HP which is identical in appearance to the standard L-2. Though motors tend to vary somewhat in power from batch to batch, the duration of the L-2 falls between 18 and 25 seconds. Fuses are included with each box of motors.

Dr Jan Zigmund, creator and manufacturer of Rapier motors has this to say about them:

The Rapier model jet propulsion units have been designed for sport and recreational flying of jet powered model aeroplanes. The units are made of a cardboard tube with a refractory nozzle and cover. The ideal thrust to weight ratio has been achieved by using suitable simple materials for the construction of the jet unit tube combined with a special propellant. This propellant has a low burning rate, low flame temperature and is able to burn at low operational pressure in the cardboard combustion chamber. A long burning time and consequent long flight time are of special interest to modellers of jet models. We hope you have many happy hours of fun flying your models using the Rapier Model Jet propulsion unit.

 

The table below, based on tests by Carlo Godel, gives comparisons between Jetex and Rapier motors:

 

Jetex motor Thrust
(mN actual range)
Rapier motor Thrust
(mN actual range)
Atom 35 100/110 L-1 40/45
50 125/140 L-2 80/95
100 250/275 L-2HP
L-3
160/175
200/220
150 Jetmaster 350/400 L4 300/325
150 PAA-Loader 750/800 - -
200 520/550 - -
350 / Spacemaster 600A 935/950 - -
Scorpion 600 1310/1400 - -


Please note: All figures are taken from actual tests done by Carlo Godel in 2001 through 2003 and reflect the actual peak thrusts obtained on a test rig of his own design calibrated with actual weights. Results may not be replicable by others. Fuels used were the older V-Max.