FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1925
1925 - 0071.PDF
i . FEBRUARY 5, 1925 LIGHT 'PLANE AND PROGRESS is not very rapid in the matter of light 'plane- clubs, and in fact things may be said to have reached prac- tically a deadlock. The two-seater light 'planes from last year's Lympne competitions, and more particularly the engines, were not considered by the Air Ministry as being satisfactory to such a degree as to make them suitable for vise by the light 'plane clubs, and in the meantime, although generally speaking the response as regards enrolment of members has been excellent all over the country, further progress is naturally stopped pending a decision. There is, we believe, a feeling in certain quarters that the Air Ministry might allow the clubs to use larger machines so as to get going, and the Avro training machine, the famous and faithful 504, has been suggested as a suitable type. The Air Ministry has, however, refused to sanction any such scheme, as the original stipulation made when it was decided to award a grant was that light 'planes were to be used. * * * Now one obstacle is that nobody has yet defined what a light 'plane is, and so far as we are aware no ruling has been given on how and when a light 'plane ceases to be a light 'plane. A somewhat curious state of affairs seems to have arisen, two schools of thought being in agreement on one point only—that the present light 'plane is not the right solution. One school maintains that the present maximum engine capacity of 1,100 ex. is sufficient, and that with a little development the 1,100 ex. engine can be made to do all that is required. The other can see nothing but trouble and expense arising from using high-grade high-speed engines, and urges that we should not bother about capacity, but should define the minimum performance which the light 'plane must have, and limit, for instance, the petrol con- sumption, or, in other words, stipulate that the machine, in order to be considered a light 'plane, must be capable of covering a certain distance on a certain quantity of fuel. * * * THERE is a great deal to be said for both points of view, but it does seem to us that the latter is likely to offer the better solution, if for no other reason than that it leaves designers much greater freedom. If the only limitation, always provided a certain specified performance is met, is on petrol, or, in other-words, mileage per gallon, the larger capacity slower-running engine will have an equal chance with the faster-running engine of smaller capacity, provided its fuel economy is good enough. And after all, capacity is not in itself of any importance whatever. What is of import- ance is the fuel consumption, and if an engine of large capacity can be made to give as good mileage as one of smaller capacity there can be no possible objection to the larger engine. * * * As an instance of what we have in mind, reference may be made to the famous Avro Baby, with 35 h.p. Green engine, on which Hinkler flew from London to Turin non-stop. That machine, or rather that type of machine, although its engine capacity was far and away above the 1,100 ex. now regarded as the maximum permissible, did, we believe, something like 30 miles to a gallon of petrol, and that at a fairly high cruising speed. The Baby was, of course, a single-seater (a two-seater version was built), and in view of the fact that the type is now several years old there is little doubt that a two-seater could now be built which would give as good mileage, and the figure of 30 miles per gallon might possibly be taken as a reasonable basis for -discussion. * * * THE mileage per gallon basis is, of course, capable of varia- tions and of extension. For instance, it might be stipulated that a light plane must be capable of covering a certain distance on a certain number of gallons at a certain cruising speed. In practice some difficulty might be experienced in obtaining accurate figures, but this should not be insuperable. At any rate, some such basis is more likely to lead to real progress than a limitation on engine capacity, and if we are to have another light 'plane competition this year, the mileage, or range, basis might well be chosen. * * * IN the meantime, the de Havilland Aircraft Company is producing a machine which is their version of what a low- power aeroplane should be to be cheap, reliable and com- fortable and easy to handle. This is the D.H.60 " Moth," to which reference has previously been made in these columns. The machine is a normal one-bay biplane with Raf 15 wing section and streamline wire wing bracing. The machine is now in an advanced stage of construction at the Stag Lane works of the company. * * * THE fuselage of the D.H.60 " Moth " is of usual de Havilland construction—i.e., a flat-sided three-ply covered box, which has been found to give such good service on commercial aeroplanes for a number of years, and which the firm has there- fore thought worth retaining. The top, as usual, is cambered or faired, while the bottom is flat. The two seats are arranged in tandem, and dual controls are provided. Behind the rear seat is a compartment for luggage, so that the machine can be used for touring as well as for instructional purposes. * * * PERHAPS the most interesting feature of the D.H.60 " Moth " is its engine, a "Cirrus" air-cooled, about which hitherto great secrecy has been maintained. This engine, originally conceived by Captain Geoffrey de Havilland, has been designed by Major Halford, of B.H.P. fame, and is a four-cylinder in line vertical. The cylinders, which are those of the R.A.F. engine, and of which many thousands are probably in exist- ence and to be had cheaply, have overhead valve gear and aluminium heads. The " Cirrus " is rated at 60 h.p., which power is, we believe, developed at about 1,850 r.p.m. At a cruising speed of 65 to 70 m.p.h., the engine is, of course, throttled down, and at that speed should be very reliable. In fact, the aim of the designers has been to produce an engine which shall be as reliable as a car engine, and very nearly as silent. It is probably not generally realised how greatly engine noises add to the discomfort of those who fly, and in the D.H.60 an attempt is to be made to reduce noise as far as possible. Mainly for this reason the radial type of engine was considered unsuitable. * * * THE undercarriage will be of simple Vee type, with rubber blocks working in compression. Considerable wheel travel will be provided, so as to give good shock-absorbing qualities, a very useful feature in a school machine. * * * IN orderto avoid the dangerous practice of " prop swinging," a starter is to be provided for the " Cirrus " engine. This will take the form of a lever in the pilot's cockpit, which, on being pulled up, operates a cable running over rollers to a starting mechanism on the rear end of the engine. In other words, it will be a form of:1 kick-starter." but operated by hand. * * * THE D.H.60 will, it is estimated, have a weight of 1,350 lbs. all up," which is considerably more than the weight of the Lympne two-seaters, but still a good deal less than the weight of the training machines hitherto in general use. The top speed of the machine will probably be about 85 or 90 m.p.h., and it is expected that a mileage of somewhere in the neigh- bourhood of 20 miles per gallon will be obtained. The machine has been produced without the blessing of the A.I.D., and at the moment there is no guarantee that it will ever obtain its airworthiness certificate. That, however, the firm is prepared to risk, and perhaps by the time the D.H.60 has flown for a few hundred hours and has proved itself thoroughly sound in wind and limb, the powers that be may be persuaded to close one eye. Certainly, so long as the Air Ministry insists upon constructors building under A.I.D. supervision, we shall never see the low-priced aeroplane, and, as we have so re- peatedly urged in this journal, constructors can be trusted not to produce machines which are dangerous. Their repu- tation is at stake, and this fact should be a much better safe- guard than any amount of official meddling. In any case, the possession of an airworthiness certificate is no guarantee, and machines designed to the official safety factors have been known to fail. * * * IT is good news to learn that France is to establish a per- manent gliding centre at Vauville, to be, as a matter of fact, a counterpart of Germany's Rhon. A permanent hangar of large size is to be erected, and there wrill be general offices, as well as a small workshop, in which minor repairs can be effected. A caretaker will be in residence on the aerodrome, so that experimenters will be able to go to Vauville at any time of the year to carry out experiments. The Vauville Council have rendered every assistance in the matter of land, and the site that has been secured by the energetic action of l'Association Francaise Aerienne is regarded as eminently suitable for experiments in gliding and soaring flight. The most difficult part of the task of preparing the site is that of making a track up the side of the hills to facilitate the return of the machines to the top, but this is being done with all speed. What are we going to do ? 71
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
