Jetex Job (oz15604)
About this Plan
Jetex Job. Free flight sport delta model, for Jetex 100 power.
Quote: "Jetex Job, by Henry Struck. The new English solid fuel Jetex engine opens up new avenues of experimentation for model airplane designers.
Anyone who has thrilled to the smooth, rushing flight of a jet fighter and longed for similar power for his models should find the new British Jetex units of special interest. The Jetex is actually a rocket-type engine, since the oxygen required to support combustion is contained within a solid fuel charge which is ignited within the container. There are no moving parts and only the lighting of a plastic fuse is necessary to set the 'engine' in action. Considered quit safe in operation, the Jetex has a spring-loaded cover to permit the gases to escape should the jet exit become clogged. The fuel itself does not continue burning in the open air when lighted with a match.
Radically new and exciting designs are possible with this power supply. The reduction of drag assumes prime importance, as the ratio of the exhaust velocity to the model velocity determines the efficiency at which the motor is operating. Weight must be kept at a minimum, to permit the model to accelerate rapidly, without wasting the thrust available.
The Jetex unit its neatly into the idea of a low-drag design. A pusher installation produces a sleek fuselage, with the small engine diameter of one inch fully cowled, provided cooling airflow over the unit is maintained. The absence of a propeller eliminates the long landing gear problem, as well as the breakage of propellers and the business of wearing one's fingers out twisting them. The lack of torque simplifies control, especially in tailless designs, while the constant and equal thrust obtained from each charge makes twin-engine types practical,.
Only a few simple steps are necessary to operate the jetex unit. Remove it from the model, where it may be mounted either on a single screw or in a spring clip - both of which are furnished with the engine. Snap off the cover and drop a charge into the case. Press the coiled plastic wick against the top of the charge with the disc of wire mesh (a supply of wicks and circular meshes comes with the engine). Replace the cover and replace the unit in the ship. Light the wick with a cigarette or match) and hold the model in flight attitude. There is no need for haste since several seconds are necessary for the fuel to generate full pressure. This moment is indicated by a steady hissing sound, and model is launched.
No batteries, props, cranking or pumping. No fuel dripping off your elbow. No screaming and roaring.
The ship illustrated was designed to test the ability of the Jetex unit, rather than to achieve the ultimate in performance. It is built to nearly the maximum weight of 3 ounces specified by the engine manufacturer. Sensitive to the slightest adjustment it has turned in many excellent flights. Upon being launched in the conventional manner - not hurled into the air - the model gathers speed steadily and climbs swiftly throughout the engine run of 20 seconds. The compact design can absorb much punishment without damage and is extremely simple to construct.
The wing is built first. It is a straight taper with 37° of sweepback, which is the equivalent of about 7° of dihedral. Lay out the planform on a flat surface to the dimensions given or the drawings. Mark off the tips in 1/4 in squares and plot the outline. Shape the leading edges from a pair of soft balsa strips..."
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Article.
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(oz15604)
Jetex Job
by Henry Struck
from Air Trails
February 1949
21in span
Jetex F/F
clean :)
all formers complete :)
got article :) -
Submitted: 25/09/2024
Filesize: 203KB
Format: • PDFbitmap
Credit*: dfritzke
Downloads: 249
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User comments
Doh. Have uploaded the missing article file now, thanks to Pit.SteveWMD - 18/10/2024
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- Jetex Job (oz15604)
- Plan File Filesize: 203KB Filename: Jetex_Job_oz15604.pdf
- Supplement Filesize: 1453KB Filename: Jetex_Job_oz15604_article.pdf
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Notes
* Credit field
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Scaling
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