SEE HOW THEY FLY!

New Zealand Listener, Volume 9, Issue 232, 3 December 1943, Page 4

SEE HOW THEY FLY!

From Rubber To Petrol In The Story Of Model Aeroplanes

NCE in Christchurch, more than 10 years ago, a group of model aeroplane enthusiasts were gathered in Hagley Park. Smart models of various kinds were being wound up, or launched, or assembled out of their special crates. There were neat scale models, monoplanes and biplanes in bright colours, and sleek models degigned solely for efficiency, in which beauty of line was a mere incidental. Along came a couple of boys with a "stick-model," a wing fixed on to a’ spruce spar, and the usual tail surfaces. Nobody noticed them particularly, but they launched their aeroplane into the dir and watched it climb. It seemed to shoot up at a violent angle, and the propeller went on spinning. In a few moments the stick model was the centre of attraction and all eyes turned upwards, away from scale models and acknowledged record-breakers. The propeller was seen to stop, but air currents had carried the little frame high up into the air. It turned its nose in the direction of Fendalton, and its excited owners dashed off on their bicycles. Others followed, and there was a little band of cyclists racing along without a care o the dangers of the road, heads thrown back and hands shading their eyes, pedalling for their, lives in pursuit (we even reproduce a picture of them here). Long after the launching, the model was lost to sight, drifting away over the Canterbury plains, known to have flown longer than any similar model hitherto. It was not a record, however, because nobody had thought of timing it with a watch. * * * UT that was more than 10 years ago, and model aeroplanes have flown a long way and developed a long way since then. Though this hobby still has its lighter side-as when a cow recently ate-‘ one valuable model because it

apparently liked the "dope" on the wings-it is a rather more serious thing these days than our artist’s drawings might suggest. We discovered this when, having noticed some tiny petrol motors in a shop window, we decided to make further inquiries. "It’s a Real Science" In the words of H. E. Righton, general secretary of the New Zealand Model Aeroplane Association, "it all grew out of the old paper-bag-and-rubber ‘model that started as a toy for boys. Now with petrol models with 10-foot wingspans, and remote control by radio, it’s a real science." _~ In other countries, this "real science" is recognised by Governments, and assisted by oil companies. It is recognised, for instance, that the Davis "airfoil" (cross-section pattern of an aeroplane wing), which is now being used ~

in the wings of Liberator bombers and other American aircraft, was developed by a sagg Fre eeigg maker. Members of the ellington Model Aeroplane Club saw the efficiency . of. this wingsection for themselves whgn their first model employing it took off and sailed away into the Tararuas. It has never been seen since. In New Zealand, Mr. Righton says, about 90 per cent of the eligible members of the various clubs went into the Air Force, and senior members now act as instructors to the model aeroplane sections of the Air Training Corps. There has been unofficial recognition of the clubs’ contribution in the present war in ways which we have been asked not to mention. There are four roughly-divided kinds of model-the indoor model that may have a span of two feet and yet weighs. only one-tenth of an ounce; the outdoor model (driven, like the indoor one, by twisted rubber); the petrol-motor machine, that may have a span of any- . thing from four to 10 feet, weighing up to 10 pounds; and the glider model that is launched out-of-doors by a tow-rope that is pulled off its hooks by a little parachute when the tension is released. , Lighter Than a Feather When Mr. Righton told us of the indoor model that weighs only one-tenth of an ounce, we wondered at first whether we had heard correctly, These models, it seems, can be constructed

with balsawood frames, the main sparg being hollow, and the flying surfaces covered with microfilm, so that far from being merély "light as a feather," they are much lighter than a feather of equal size would be. Microfilm is the name given to a membrane obtained by pouring a cellulose liquid on water, and then lifting it off and drying it. Balsawood is a very light wood that comes from South America, where the word means "raft." It is used nowadays in "grown-up" aeroplanes, too- Hudson bombers employ it as an insulating material in plywoods. Indoor models, such as have been known to fly for 16 minutes inside a large building, bear little resemblance to the model aeroplane. They have a big propeller that merely idles round, driven by a loop af rubber three-sixty-fourths of an inch wide, twisted 2600 times-by a 10-to-one geared winder, as Mr. Righton ickly explained, when we queried the e. Rubber-driven outdoor models pe as have entered in the Wakefield a Moffet contests (flown by proxy flyers), are the more familiar style of thing tanging from the conventional high-wing monoplane that bears some resemblance to the small one or two-seater aeroplanes of the ’thirties, to the more abstracted design that has wingtips bent upwards, extra vertical surfaces underneath the tail, and a propeller that folds up like a moth’s wings to lengthen the glide when the rubber motor has run down. Mr. Righton showed us a photograph of one answering to this description, built by a _ Chinese boy in New Zealand, which won sixth place in one of the Moffet Contests. "We rely on gliding time being three times the time of the power-flight. That one has blades that fold back into that position when the tension is released from the rubber." Binoculars Forbidden There is a strict code of rules, accepted internationally, under which contests may be conducted and results recognised. Timers may not follow the aeroplanes as they drift; they may not move more than 12 yards away. Nor may they use optical pret _ eve! than sunglasses! Once out of sigh model has finished it’s flight for urposes, Flights of 20 minutes and more have become the accepted thing since petrol "motors were introduced, In 1935, Mr. (continued on next page) —

(continued from previous page) Righton remembers that there was one petrol motor, an imported machine, in the club he belonged to. Members made their aeroplanes with identical fittings on the nose, and took turns at fitting the little engine on and flying their models. The petrol motor may develop anything from one-tenth to one-quarter horsepower. It is rationed with a mere eye-dropperful of petrol, enough to last a minute and a-half, and an éfficient

model ciimbDs about 1000 feet a minute, so there is plenty of room for a_ long glide. "More Efficient Than Real Thing" "As a matter of simple fact," said Mr, Righton, "a model is far more efficientin the sense of effective use of power and design-than the real thing. If we build models to the exact design of real aeroplanes, they’re no good. You have to have a pilot to cortect the inefficiencies of a full-sized aeroplane. A model has

to be designed to take off neatly and come down neatly-if it does the one all right, it’ll do the other. It has to have natural stability, not merely correctable stability. It is in the seeking of these things that features of the model aeroplane have been developed which were later found ideal for the real aeroplane -the Davis wing-section, for instance." Some hints of the future possibilities of radio-controlled model aeroplanes had been given before wartime emergency regulations forbade the use of radio transmitters by civilians, Remotecontrol units had been used in New Zealand, with a code system operating the variation of control surfaces (In America some amateurs had got as far as.using a joystick to actuate the transmitter). One Wellington man flew a large model out to Kapiti Island and back to the mainland, causing it to brush past the five-foot rod that acted as his aerial. "After the war, I think we'll see them performing evolutions, rolls, loops, spins and dives," said Mr. Righton. "And, of course, we won’t need the large fields that we need now for our unpredictable flights." We'll be able to bring them down just where we want them, and make them do nice, neat, three-point landings."

Model aeroplane club meetings had grown to great proportions before nearly all the members went off to play aeroplanes in a much bigger and more realistic way. "Terrible Lot of Exercise" "It’s a great social activity," said Mr. Righton. "It combines a certain amount of craftsmanship with a maximum of outdoor activity. It’s not like model engineering or anything of that sort, which is purely a workshop hobby. You’re out of doors the greater part of the time, and you get a terrible lot of exercise." In peacetime one club had the use of an inland aerodrome which had been established by an aero club that no longer had any aeroplanes. Hangars, haunted by the shades. of real aeroplanes that had crashed long since, were used by "modellers," who brought their machines together for an annual camp at Easter. There were 50 there one year. In the South Island, at a contest for petrol-driven models held in 1938, there were 140 candidates present. "At a big contest, of course, there’s something at stake," said Mr. Righton, "and it’s more a matter of temperament. There’s a lot in the preparation and launching, and you learn that the hard way. It’s not all in the designing by any means. The best built machine isn’t a foregone record-breaker, as some clumsy stick models have shown." Club meetings have had their amusing side-as our artist suggests in his drawings. There was the time when a petrol model ‘resembling a real "aeroplane at a distance was being flown up the Hutt Valley, and the wings came off

in mid-air owing to faulty rubber, for all detachable and vulnerable parts, including the motor, are strapped on with rubber to minimise crash damage. The motor was still going and the body plunged to the ground-a total wreck. A few minutes later, some motorists came _ running across to know how many people had been killed!

Mr. Righton assures us that if there is one fence within 30° acres, a valuable model will make for it on landing. "It’s psychological," he says. "And if you leave a model in a field where there are cows, you may be sure one of them will come along and take a bite. They seem to like the smell of the dope we use to tighten the fabric."