SLIP STREAMS

Sailplanes and the Ultra-Light Plane.

oNE result of the demonstrations which Kronfeld and Magersuppe have given in various parts of the country during the past two months, h:is been a certain reawakened interest in the ultralight ‘plane.

People examined and admired the wonderfully clean lines of the “Wien ” and the Kegel “Professor.” And having done so, some of them, as they turned away, remarked that all these machines needed was a “little engine stuck on somewhere.” Such a suggestion is strongly deprecated by glider enthusiasts who are most anxious to keep sailplaning entirely clear of powered flight in any form, while others declare the motorisedglider to he dangerous and unsatisfactory except in the most expert hands.

Nevertheless, it is a fact that one or two machines of the ” Wien ” calibre are now being planned by amateur constructors, so that it is possible that we may yet see the return of the ” pip-squeak ” after all. It should be born in mind that the design of motor cycle engines, such as were used in the Lympne competition have improved vastly since 1922, and as lack of power and unreliability were the chief troubles with the early machines, it is reasonable to suppose that a modern edition would make a very much better showing.

More Foreign Machines.

In spite of the fact that British built machines practically hold the monopoly in the light ‘plane movement in this country, the number of foreign aircraft firms which are represented here is increasing.

One of the latest arrivals is the Romeo Ro. 5, made by the aviation section of Alfa-Romeo, the famous automobile concern. • The first demonstration Model was flown from the works at Naples to Norwich by Mr. W. G. Pudney, late R.A.F., who is the English concessionaire. The ” Ro. 5 ” is a tandem two-seater parasol monoplane, and except for the wing spars and ribs and covering, it is entirely. of metal construction. The engine is an 85 h.p. air-cooled radial Fiat, and the machine has a top speed of 105 m.p.h. and cruises at 95 m.p.h. In this country, where it is shortly to be built under licence, it will be fitted with an English power unit. The ” Ro. 5 ” has already distinguished itself by winning the extremely searching competition for the best light aeroplane held by the Italian Government, at Monticello last year.

Another foreign newcomer is the Belgian Bulte, training plane. This machine is a two-bay biplane of orthodo design and is fitted with a 140 h.p.. Anzani Engine. It is claimed to have a very slow landing speed, a quick take-off, and other qualities which make it admirably suitable for primary instruction or private flying. Itlis being marketed by Sealandair, Ltd., of 142, Long Acre, London, W.C.2, the price being £675.

Diesel Developments.

Slowly but surely designers are progressing in the evolution of -a satisfactory heavy oil engine for aircraft. the Continent, in England and in America I.C. engineers have, for several years, been struggling with the many problems which lay in their path, but it seems now as if the Diesel aero nlotor has reached a stage when It…4as passed the experimental and reached the practical production, form.

One of the great advantages of the type is, of :course, the elimination of all risks of fire (gas-oil, which is generally used in Diesels, does not give off inflammable vapours below 90° C). But there are several other features which weigh heavily in its favour. Whereas the carburettor of -a petrol engine is extremely sensitive to varying conditions of temperature and altitude, the influence of the latter on the running of a crude-oil power unit is negligible. Again, owing to its working cycle there is a reduction in heat loss from the cylinder walls and the exhaust, and thus the valves are not subjected to such a high temperature as in a petrol engine and a quieter exhaust note is possible. Finally, there is the highly important commercial consideration of low running costs.

Recently a number of very successful flights have been carried out at Turin with a Fiat biplane fitted with a 180 h.p. six-cylinder crude oil ,engine. Special interest attaches to the machine, as the power unit was not designed and built throughout as a Diesel, but was one of the well known Fiat A.12 motors, modified to run on heavy fuel. Many of the parts were identical, but the Cylinder bores were reduced from 160 in.m. to 140 ni.m. in order to lower the internal stresses to the same values as when the engine was in its original form.

Ground Instruction.

An interesting machine to teach the elements of flying reached this country recently and was demonstrated by Shell-Mex, Ltd., to a Lumber of people in London last month.

The idea is to reproduce, as far as possible, the conditions in a pilot’s seat, to teach the feel of the controls and to show how they actually operate and how they cause the craft to execute certain manoeuvres.

The ” pilot,” therefore, is provided with a real joystick, a rudder bar and throttle, etc., exactly as in the cockpit of an aeroplane. These are fitted under a table at which he sits. On the table at his eye level is a large glass case with, at the forward end, a.motor and propellor to project a wind of up to 70 m.p.h. through it, this being controlled by the opening of the throttle.

In the centre of the case is a captive aeroplane in model form and the rear end of the case is open so that the pilot Will feel the wind in his face exactly as in real aircraft.

” RUDD.ERBAR.”