Flight of the power-saw

Press, 29 October 1977, Page 17

Flight of the power-saw

By

LLOYD TIMBERLAKE,

NZPA-Reuter

science editor

Strange things are happening in various parts of the aviation world w’hich promise to make individual motorised flight cheaper than running a car. In most cases not the aeriospace industry', but the enthusiastic amateur, is responsible for these developments. British hang-gliding pilots met recently to discuss the latest advances in attaching small motors, powering small propellers, on their kite-like aircraft. All agreed, according to “Flight” magazine, that they were not trying to re-invent the aeroplane but to get into the air more easily, and even to fly more safely.

Such pilots now launch their floppy gliders from hills, often crashing back into hedges and trees before getting clear of ground turbulence. Now pilots are experimenting with mounting two-stroke engines on the cross-bar beneath the sail. Through a flexible drive-shaft this turns an a f t-mounted propeller, which can take the craft up to the smooth upward thermals at about 300 metres.

The best package at the meeting, according to the magazine was put together

by Murray Rose, who used a McCulloch 101 engine able to run 10 minutes on a full tank of petrol — only 1.4 litres. This motor enables a Midas glider to climb at a rate of 46 metres a minute. His whole craft only weighs 34 kg. British flying rules des-

cribe a hang-glider as an aircraft capable of being carried, launched, and landed solely by the energy of the pilot on his own legs, and the new motors do not upset this definition. A United States firm, Ultra-light Flying Machines, is producing a power package for its successful “Easy Riser” craft, a biplane hangglider with rigid wings which won last year’s United States national hang-gliding championships.

The McCulloch 101 123 c.c. engine and fittings sell for just under $7OO, while the aircraft kit costs about $BOO, allowing the do-it-yourself enthusiast to build his “aeroplane” for a fraction of the cost of most cars.

The engine, with a 5.7 litre petrol tank, is mounted close behind the pilot. Thus he must be able to cut it off instantly when coming in for a landing, emergency or planned. This he does by opening his mouth, letting go of the compression release line

has been clutching in his teeth. The most bizarre development in cheap powered flight comes from Japan, where, according to “Flight” magazine, a glider pilot named Onishi mounted six 10 c.c. model aircraft engines on a boom in front of his commercial glider’s wings, three to a side. This tout of 103 horsepower Hits the “Onishi OS-G 3” off the runway after a run of about 150 metres. The plane cniises at 40 km/h, but stalls (drops out of the sky because of lack of forward momentum) at 35 km/h, leaving little margin for error. Onishi weighs 70 kg, while his plane weighs 65 kg. Another, much better

publicised, development was the August 23 flight in California of the “Gossamer Condor,” which, under the pedal of a racing bicyclist, Bryan Allen, completed i 22 km figureeight course. The 34 kg, 30-metre wingspan craft was built of plastic. aluminium, wood, and piano wires to capture the $89,000 prize for the first such manpowered flight. It is an expensive, fragile, and highly unstable aircraft, given to pitching into the runway at the slightest gust, but experts think the designer, Paul MacCready, the 1956 world gliding champion, has come up with some important light aircraft technology and design for his peculiar bird. For instance, he has done away with the tailplane. The “pilot-motor” sits in a thin gondola which acts as the fin, and a swinging horizontal control surface in front of the craft steers it. These innovations, modified and coupled with some of the new light engines available, mean that the motorised glider could soon become as common a status symbol in the middle-class households of the world as the second car is now.