Swish (oz8269)

About this Plan

Swish. Free flight sport model for Jetex 100 power.

Quote: "THE Swish is a free flight jet-propelled developed especially for the new Jetex power unit recently invented in England and now becoming available in this country. For the writer, this ship proved the most interesting and unusual project yet encountered - stick around and see what we mean!

The Jetex motor is manufactured by Wilmot Mansour & Company Ltd, Salisbury Road, Totton, Hants, England, and a fiendishly clever gadget it is! It is at present available in two sizes: Jetex 100 for models of 16 to 30 in span, and Jetex 200 for ships of 24 to 42 inches. The smaller unit has a thrust of 1 oz lasting for 20 seconds; the larger unit a thrust of 1-3/4 to 2 oz for 20-40 seconds. In appearance the unit is, roughly speaking, an aluminum cylinder of about 1 inch diameter, with a removable end held firmly in place by three strong spring-loaded clamps. The fuel is a 3/4 in long solid, cylindrical in shape to slide into the cylinder, and hard and brown, resembling a slice from a wood dowel. The small Jetexs takes one of these charges, the bigger unit two charges. A fuse is coiled to fit against the charge inside the cylinder with one end protruding through a small hole in the center of the removable end of the cylinder. The escaping gases passing through this hole provide the thrust.

A lot of questions will spring to mind. How does the fuel burn? Is it safe? Dose the unit get hot? How strong is that thrust when it comes to flying a model? First of all, the fuel was found quite safe and simple to handle according to directions in the instruction booklet. It burns with a gentle hissing sound, more like a swish when the ship is in flight (from whence the name 'Swish'). The unit does get hot but not dangerously so. As long as the metal of the unit does not come into direct contact with paper or wood there is no danger of the heated metal igniting the structure. While it does get too hot to handle with the naked hand, the heat is far less than one would expect. As to thrust, the Jetex seems incomparably better than using a CO2 capsule as a straight jet, but not as 'hot' in our estimation (at least in this size model) as the performance of a good CO2 engine. It has, however, ample thrust for good sport flying and definitely is not a disappointment, This observation is based on the performance of the Jetex 100; the larger unit was not available at the time of these experiments.

A point that should be made immediately is that the first model followed closely the suggestions of the Jetex booklet; it is possible to develop other sized models - for example, it may be possible to fly this same size ship with a larger unit, or to experiment further with different size and weight ships.

In designing a ship for the Jetex it is essential to keep in mind the proper cooling and ventilation of the powerplant. A minimum space of 1/16 most be left between the engine and any cowling or side of a fuselage. A good air flow seems essential... "

Quote: "SWISH by Bill Winter November 1948 Model Airplane News. Scanned directly from my issue of the November 1948 Model Airplane News is Bill Winter's SWISH.... could be another option for the TBD. It's for Jetex power and looks like a nice design... Enjoy, jeff"

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