Electric Round the Pole Flying - a new idea?Although electric RTP flying is growing in popularity the concept is by no means new.
For many years aeromodellers have attempted to build and fly electric powered model aircraft, but their efforts have generally been frustrated by the lack of suitable motors. The problem was mainly the difficulty of making electric motors sufficiently light in weight and sufficiently compact, yet still possessing power enough to produce the necessary revolutions for the propellers to generate enough thrust for flight.
Fortunately today the problem no longer exists thanks mainly to the popularity of miniature model "slot car" racing. With the increase in the following for this new sport came the necessary incentive for the development of more efficient electric motors. Model manufacturers strove in competition with each other to produce the "hottest" "lightest" "most powerful" power plants that could be fitted into the slender shells of these "Grand Prix" miniatures. The benefits of all this research has rubbed off on the electric model aircraft enthusiasts who are now presented with a large choice of readily available motors quite suitable for airborne use.
The first signs of serious attempts at developing electric round the pole flying became apparent at the early post-war model aircraft exhibitions held annually at the Dorland Hall, Regent Street, London. In January 1945 crowds of people visiting the exhibition were enthralled by the sight of an electric powered model Miles Magister tethered by 7ft. 6in. wires to a central pylon, taking off, circling, and landing back on a specially prepared concrete circular runway. This 1 inch to 1 foot scale model by Mr. J. S. Evans of Kettering flew more than 1,000 miles during the space of a week, wore out a pair of wheels and two electric motors, and left its impression in the concrete, caused by the wear and tear of the tyres!
J. S. Evans Famous 1/12th scale Magister in flight
Members of the public were invited to try their hands at flying the Magister in return for a small donation of 6d. per flight, the grand accumulated sum of £35 was presented to the R.A.F. Benevolent Fund at the close of the exhibition.
So popular was this spectacle, that in the following year. 1946. it was decided that two circular Perspex runways would be constructed, one mounted above the other to facilitate simultaneous electric flying.
Again Mr. Evans thrilled the crowds, this time with a 40 inch wingspan scale Vickers "Viking" airliner weighing 2 1/2lbs. This superb model was powered by two 9oz. 18-volt motors, each developing 3,000 rpm (plans for these, RTP238X. 50p) with a flying speed of 25 mph. The "Viking" incorporated a retractable undercarriage and was controlled from a panel which ingeniously included a red warning light coupled to a warning horn should the model nose down for a landing with the undercarriage still in the "up" position. The red light was automatically cancelled by a "green" the moment the undercarriage was safely locked down. During its exhibition the Viking flew a distance of well over 3,000 miles.
The renowned Vickers Viking RTP model (Plans still available) RTP 237X price 60p
Vickers Viking plan
Flying from the lower Perspex circular landing strip, a 7oz. design by Flt. Lt. Tucker, the "Vertric" demonstrated the use of elevator control. Wool tufts were attached to the wing tips to illustrate the effects of "tip vortices" to the audience, supported by a commentary.
Although plans of Mr. Evans' Vickers Viking appeared in the "Aeromodeller" for the months of May and June 1946, and many of these plans (still available as RTP237X: price 60p) were sold through the Aeromodeller Plans Service, electric R.T.P. flying did not at that time gain the popularity that was hoped for. For many years electric R.T.P. remained somewhat the "Cinderella" of the world of aeromodelling, no doubt due to the complexity of having to produce one's own electric motors.
Undoubtedly "specialists" were still experimenting with this type of flying, and in September 1963 scale model enthusiast Doug McHard published a most enlightening article on the subject in "Model Aircraft." Mr. McHard described his experiments using low voltage imported Mabuchi 25 electric motors incorporated in those evergreen popular cheap free flight rubber scale Keilkraft kits. His models were flown on 6ft. 32 s.w.g. enamelled wires, the power being led out to the aeroplane from a model train mains transformer/controller via a central pylon which incorporated an electrical distributor. Undoubtedly this article did much to inspire many modellers to pioneer this new form of flying.
Doug McHard's Sopwith Camel which performs well with a 16D type motor and 4:1 gears driving a KeilKraft nylon 5x3 prop
The 1968 Model Engineer Exhibition at Seymour Hall, London, showed a revival of interest in this comparatively untouched branch of aeromodelling. Perfectly standard Frogflite kit models had been adapted to take Riko "Whip" 16D slot car motors, and flown by the staff of Model & Allied Publications Ltd on .030in. shellaced copper wires, the models received applause from the enthusiastic audiences.
Following a series of experiments in a local school hall by the staff of Model & Allied Publications Ltd.. a heartening article on electric R.T.P. flying appeared in the March 1969 "Aeromodeller". Conclusions reached were that any standard Frogflite kit model could be successfully adapted to fly with the aid of an electric slot motor, and larger more sophisticated model aircraft could also be modified to fly "electric" by modellers of limited building experience. The secret in this case was the use of simple reduction gearing in the region of 4:1. this permitting the use of larger propellors.
The same year, 1969, saw the publication of another informative article by American electric R.T.P. exponent Pat March. Included in his article in the "American Aircraft Modeler" for August, were plans of his highly successful sport design "Voltswagon" details of which appear elsewhere in this book.
The effective results of all this published "know how" became apparent in 1970 when electric model flying clubs and groups began to spring up in many parts of the country. One such group of flyers, a branch of Grantham and District Model Aircraft Society, were fortunate in having obtained the regular use of a large R.A.F. drill hangar. With so much available space they were able to "spread their wings", starting at the beginning with lines of 15 feet they progressed rapidly until the sight of four models flying simultaneously around one central pylon on 40ft. lines was just a weekly occurrence!
1970 was significant to all electric enthusiasts. The demonstrations of electric model flying at the Model Engineer Exhibition were of remarkably high standards. The central pylon carrying the power wires to the model aircraft was erected on an "island" in the centre of a large circular model boating pool. The runway strip surrounded the pool and added "interest" to the landings and take-offs, the misjudgement of which quickly converted the aircraft to an unfamiliar role - that of submarinecraft!
This outstanding display of modelling ingenuity left even the sceptics of the modelling fraternity with not the slightest doubt that electric R.T.P. flying was "growing up". Keen R.T.P. flyers from Bristol, Debden, Grantham and Luton turned up in force with a selection of models, the equivalent of which had never been seen before, scale, stunt, speed, multi and novelty models, all driven by slot motors. An example of the sheer ingenuity and originality displayed was an electric powered Republic "Lancer" P.35 which American modeller Pat March had shipped across the Atlantic for the Grantham lads to exhibit. This beautiful metal foil paper covered scale fighter incorporated a retracting undercarriage operated via a polarity reversing switch.
Three Frogflite kits which adapt easily to Electric power are the Ryan PT.20. D.H. Chipmunk and the Hawker Fury in photographs opposite. Each uses the 16D size motor and has been employed at the Model Engineer Exhibition displays.
We have barely "scratched the surface" of this comparatively untouched field of aero-modelling. If you like exploration, read on!