Bobcat (oz903)


Bobcat (oz903) by GW Worthington from Aeromodeller 1946 - plan thumbnail

About this Plan

Bobcat. Control line model for Ohlsson 23 power.

Quote: "THE Bobcat was designed round the Ohlsson 23 with the idea of building a practical U-control model of realistic appearance. The result is one of the most beautiful control-liners ever made, that combines scale looks and high speed with sturdiness and accessibility of working parts.

The model can be taken apart completely and quickly, including removable dorsal fin, wings and lower cowlings, while the upper cowling hing6, giving access to engine and control-line system. This cowling is opened to re-fuel, and then snapped shut - the wire clip is strong enough to hold it down in flight. Cowling must NOT be left open while starting engine.

One block of balsa 3-1/2 x 5-1/2 x 19-1/2 in is required for the fuselage, or two separate blocks, one 3-1/2 x 2-1/2 x 19-1/2 in and the other 3-1/2 x 3 x 19-1/2 in. Such block is on the market, as knowledgeable aeromodellers will have already discovered.

The landing gear fits into the wing spars and is capped with pine blocks. Wing spars are made of 1/16 in ply laminated on both sides of 1/8 in balsa sheet. The removable wings are bolted through the wingspars to the plywood fuselage formers.

Brass or aluminium tubing is used for the U-control arm, which simplifies the work and is very rigid. The ends of the tubing are flattened and holes drilled for bolt at the control plate and for the wire actuating elevator. Before installing wire in the elevators it should be passed through the hole in the tubing - this obviates soldering. The control system is completed by fitting a small block between the engine mount and the fuselage. The block extends 1/8 in over and above the engine mount. A hole is drilled through this block and engine mount for the bolt holding the control plate. Two nuts are used at the control arm to allow setting of free movement of controls.

Test Flights. Newcomers to U-control are recommended to use 30 ft control lines for testing. An indoor testing site such as a hangar is ideal - otherwise a windless day must be chosen. When the 'feel' of the lines has been acquired, flying on standard 60 ft lines may be attempted. Set engine at speed and allow 'plane to take off by itself..."

Update 08/06/2019: Replaced this plan with a clearer version (patterned background removed) thanks to JJ.

Direct submission to Outerzone.

Supplementary file notes

Previous scan version.


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Bobcat (oz903) by GW Worthington from Aeromodeller 1946 - model pic


Bobcat (oz903) by GW Worthington from Aeromodeller 1946 - pic 003.jpg
Bobcat (oz903) by GW Worthington from Aeromodeller 1946 - pic 004.jpg

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User comments

Definitely and heavily inspired by the ill-fated Napier Heston Racer of 1940, if any. - Look it up on Wikipedia.
Martin - 09/06/2019
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