Osprey VI (oz13728)

About this Plan

Osprey VI. Control line speed model, for .40 engines.

Quote: "Osprey VI, by Peter Halman. An ideal introduction to control-line speed flying. Use any 'hot' 0.40 engine, fuel of your choice, and try your luck around the pylon in the new Class 6N contests.

EARLY IN 1976, the SMAE sub-committe for control line speed decided to try to encourage more people to fly in what they consider to be the greatest contest class. In order to achieve this, some kind of newcomers event was clearly needed, and after a great deal of thought, it was decided to base the event on the current SMAE Class 6, which calls for engines of 5.01 to 7.00 cc to be flown on line(s) of 19.90 metres length, and with a recommended minimum diameter of .020 in for monoline, .0148 in for two lines. For this new class however, two .018in dia-meter lines are required and in order to qualify for entry in this event, a competitor must not have scored more than 80 per cent in any SMAE handicap speed contest, other than Class 6N. The record for this new class has provisionally been set at 150 mph.

This class, which in effect means that 0.40 engines will be used was chosen because (a) there is a wide choice of engines available (almost any of the current crop of rear valve .40s, and one or two front valve units, are suitable) and (b) by flying to Class 6 rules, which have the longest lines used in SMAE events, the speed of rotation of the flier would be reduced. This makes flying much easier!

The model has been made deliberately large to make flying easier, and semi-asymmetric to cope with the weight of the two .018in wires. This layout has proved better at the critical take off stage as the large inboard wing lifts the wires at slow speeds. Osprey VI has been kept simple, avoiding the use of exotic materials whenever possible, although five minute expoxy was used throughout the construction.

A full length pan was chosen to give both ease of construction and strength. Of the pans currently available, namely the Harter and OPS, the OPS unit was chosen and this is easily available through Irvine Engines or their stockists.

Wing: Start by cutting the basic wing shape from 3/8 medium balsa sheet, then cut out the centre of the inboard wing as shown on the plan. Groove this piece for the lead-outs and cut the bellcrank hole to give 1/16 in clearance round the bellcrank.

Epoxy the cutout back into the wing, taking care to ensure that the grooves remain clear - this is easily achieved by pushing 14 swg piano wire through the grooves, but do not forget to take the wire out before the epoxy cures. Use masking tape to hold the wing together. When the epoxy is cured, relieve the centre section to accept the bellcrank mounting plate. Epoxy the plate into the wing..."

Osprey VI, Aeromodeller, August 1977.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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