Buzzcopter (oz13083)

About this Plan

Buzzcopter. Free flight helicopter model.

Quote: "Helicopters are Fun! Says Francis G Boreham.

BUZZCOPTER is one of a series of underslung engine torque reaction helicopters starting from Francis Boreham's successful 'Spraycopter' , which flew at NH Gala 1961. This model has the advantage of flying either tethered or in free flight and is also capable of rising from the ground.

Auto-rotation is reasonably good even with the two bladed rotor, as the freewheel isolates the engine and propeller unit completely, thus permitting higher rotor rpm and eliminating the drag of the usual top mounted engine.

Construction is quite simple and straightforward, though perhaps unusual for the average aeromodeller. It employs many novel components, but can be made easily in the average home workshop. Main structure is of aluminium tubing but alternatively balsa could be used since the design of pylon and engine unit permits the same drive to be mounted in various type fuselages either built up or in flat sheet silhouette form.

The important top and bottom bearings are brass tubes or bushes soldered to tin clips bolted to the pylon tube, which should be plugged with wood inserts at these points. The vertical drive shaft is a 15 swg cycle spoke which can be screwed into the engine back plate if it has such a tapping for the tank and locked with nut or screwed nipple. A small bob weight on wire stays balances the offset cylinder and is attached to the engine bearers by small bolts. The fuel tank is a small size tin control line type approximately 1-1/2 x 1/2 x 1/2 in, and is retained by a tin clip soldered and then bolted to the bearers opposite the engine cylinder.

Springy wire u/c legs coupled with the bamboo front skid gives necessary ground clearance. Wheels are not fitted as they are not required for vertical take-offs. A rubber grommett or thimble on the propeller nut guards the engine for heavy impacts. The tin lid hub is provided with a brass tube or bush soldered in the centre and should be an easy running fit on the rotor axle.

The rotor blades are connected to the drive shaft by a dog clutch, permitting the blades to free wheel when the engine is not running, and allowing a slower rate of descent. This item, while improving the performance, is not absolutely essential, and those building the simplest possible model may like to discard it and lock the rotor hub to the drive shaft by soldering.

Care should be taken to keep the weight as low as possible and all up weight should be under 6 oz. using the Quickstart Dart engine.

It will be realised that a light model will be able to climb higher, and descend more slowly than a heavy model. For early test flights, try out in calm air and ROG only after experience of several flights. To hand launch, hold the helicopter by the tubular structure in front of stabiliser, and when rotor rpm is steady, simply release - do not throw into the air.

For tethered flying use light cord or thread attached to the bolt securing the stabiliser to the fuselage."

Buzzcopter, Aeromodeller, April 1964.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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