Flight, July 1939

THE NEW CYGNET
Production Version of an All-metal Private-owner and Training Type with a Tricycle Undercarriage : Alternative Power Units

   SINCE the major attentions of the aircraft industry have recently been directed towards the manufacture of military types, not a very great deal of energy has been applied to the problem of deciding on and actually making a specialised machine for the private owner and the club. During the past year, in particular, doubts have been expressed about the potentialities of this market, and the tendency, except in one or two important cases, has been to leave it well alone. The fact is that only after quantity production of such a type has been started - with the consequent reduction in costs where metal construction is concerned - can the potentialities of the market be properly discovered. Only a firm with ample backing can take the plunge, and then only with a machine which has some, or all, of the features which are likely to remain or become commonplace during the next year or two.
   The Cygnet, which was the first stressed-skin metal-covered aeroplane in the lighter class to be made in this country, is now a product of General Aircraft, though the prototype was originally designed and made by C. W. Aircraft, one of whose directors, Mr. Chronander, is now in the G.A. design office. Consequently, the company has not had to start at the very beginning, and the prototype has been flying successfully during the last two years. Since General Aircraft took the machine over it has been considerably modified, notably in the application of a tricycle undercarriage and in the fitting of a twin-rudder tail unit. At the same time, practical experience has shown the need for detailed alterations, and the entire design is now even more capable of quantity production at reasonable cost. Naturally enough, an all-metal machine, however carefully designed, is not likely to be particularly cheap, but by way of compensation it should be more robust and more capable of standing up to exposure in all weathers. This last should give the Cygnet a special appeal in the Colonial markets.
   At first glance the General Aircraft Cygnet, with its tricycle undercarriage, is somewhat quaint in appearance, but the manufacturers are probably correct in thinking that not only will this quaintness "wear out," but that this type of undercarriage will, in anv case, be more or less universal later on. With the tricycle goes the twin-tail arrangement and limited elevator control. These ensure viceless characteristics both on and off the ground, particularly when they are coupled with a structure designed to withstand rough usage.
   Apart from providing directional stability at and after the stall, the twin-rudder arrangement means that there is little or no tendency for the machine to swing at any throttle opening, since the directional surfaces are outside the slipstream area. The limited elevator control means that, in normal circumstances, the Cygnet has a safe measure of lateral and directional control even when the column is held right back against the stop.
   There is no need here to expatiate on the principles and advantages of the tricycle arrangement, which not only permits a landing to be made at any reasonable speed with out the possibility of ballooning, but also offers that almost
more important advantage of directional stability while taxying, taking off and landing. A machine so equipped can be handled on the ground like a car.
   The structural features of the prototype Cygnet were described in Flight of December 10, 1936. Briefly, the machine is a low-wing cabin side-by-side two-seater. The wing is built up in three major parts - the centre section and two outer extensions - though the production model has detachable wing tips for ease of manufacture and damage replacement. Treated as a whole, the wing has two extruded alloy main spars and solid diaphragm ribs. Shear and torsional loads arc taken by the duralumin skin covering.
   The fuselage is partly of monocoque and partly of steel tube construction, the basis being a duralumin "box" which is bolted to and helps to stiffen the centre-section spars. Fore and aft of this section are the steel tube structures, which are now riveted and not welded. The triangulated structure behind the centre section is attached at four points to the forward end-frame of the monocoque remainder of the fuselage. The tailplane, which is generally similar in structure to the wing, is carried on a special built-up and faired-in support at the rear of the fuselage, and has the fins and rudders at either end. In its latest form, with a tricycle undercarriage, the main undercarriage legs are, of course, attached to the rear centre-section spar, while the forward leg is attached to the fireproof bulkhead through a shear panel. The cabin enclosure is not part of the basic structure, and its aft portion fairs into the rear fuselage.
   As already explained, the changes made in the production type have been partly those designed to simplify manufacture, but a number of detail modifications have been made in the light of test experience with the prototype, and it has been necessary, of course, to re-stress the centresection area in order to take the extra loads involved in "tricycling" and the forward bulkhead is now designed to take a proportion of the landing loads. The oleo-pneumatic legs of the undercarriage are, incidentally, of General Aircraft design, and all three are carried in Elektron castings bolted to the rear spar and the forward bulkhead respectively.
   Superficially, and forgetting the tricycle and twin rudders, the most noticeable difference is in the design of the cabin; this is six inches deeper, so that the pilot and passenger have a very much better view, and entry on each side is made through sliding doors. These doors have runners which travel at the top in two channels in the central roof member, and at the sides in similarly curved channels. Not only is it now very much more easy to enter, but the doors have been designed so that the machine may, in warm weather, be flown with one or both of the doors slid back, either partly or entirely. Each is held in its intermediate position by a spring-loaded pin arrangement. With such a range of door-opening adjustment no separate sliding windows are provided. The roof section of each door is of special tinted glass to keep the interior cool and to prevent dazzle.
   Each of the seats is adjustable fore and aft on slides, and the backs are high enough to give ample support. One small practical point is that the seats themselves spring up backwards out of the way when there is no load on them, so that in stepping into the machine there is no possibility that muddy shoes will touch the upholstery. The seats are designed to take parachutes. The forward bulkhead is soundproofed with asbestos wool between the bulkhead structure itself and a perforated covering panel, which is itself part of the soundproofing scheme.
   In the prototype the front undercarriage wheel could be locked in the fore and aft position in order to simplify the take-off. In the course of experiments, however, the trail angle of this wheel has been so designed that the locking device may now be omitted. The wheel is still, of course, directly steerable through the rudder bar. All three legs are fully cantilever.
   In order that no possible trouble shall be experienced with air or vapour locks in the fuel system, this, with its collector-box, has been very carefully designed. The vent pipes from each of the two tanks are taken to a single point by the highest practical route so that there is no risk of an air-lock after taking up a semi-aerobatic attitude, and so that the static pressure is the same in each tank. The collector-box, too, has its own vent, and the main fuel tap is on the engine side of the box; consequently, it is not possible to fly on individual tanks. A non-return valve prevents the fuel from passing between one tank to the other; these, therefore, must be filled separately, and there is no chance that a temporarily false level will be given in one or other during the refuelling process. The tank levels are read off in the cabin by constant acting hydrostatic gauges. The total fuel capacity of the standard Cygnet is thirty gallons, while three gallons of oil are carried in a tank in the leading edge. As a final safeguard, the dashboard fuel tap control is arranged with the ignition switches so that the latter cannot be switched on until the former has been turned on. The filler caps are in recesses in the wing which take any overflow.
   The dashboard has been arranged so that complete blind-flying equipment can, when required, be fitted without alteration, and this will be carried in a special panel in the centre, with the normal instruments on either side. The pull-type brake lever is in the centre of the dashboard with the ignition-cum-fuel arrangement a little to its right. A complete dual control system is a standard fitting, with the throttles on each side of the cabin, and there are cubby holes for incidentals below the dashboard. The flap operating switch is on the right side of the panel. This switch controls, the Theed vacuum system, the container for which lies between the dash and the forward bulkhead. As in the earlier machine, the flaps are of the normal split type and are in two sections, each extending from the centre section to the aileron. The vacuum “power” is obtained from the induction system in the usual way, and the container carries sufficient depression for operation of the flaps in the event of engine failure. By moving the control switch to “off,” the flaps can be left in any position between fully up and fully down.
   Fore and aft trim is carried out by means of the normal tab, but in this case the control is irreversible, so that there is no chance that the tab may move and so alter the trim. Either a Gipsy Major of 130 h.p. or a Cirrus Major of 150 h.p. may be fitted to the Cygnet, and it is worth mentioning here that for simplicity of manufacture the engine mountings are quite straight and have no kinks.
   A good deal of attention has been paid to the provision of inspection facilities at various points of the structure.
and such items as control details can be reached through rubber inspection doors. Quick-acting Oddie fasteners are used throughout. For the manufacture of the various parts, small stressed items such as ribs are made in an hydraulic press, while all shapings, including the cabin covering and engine cowling, are worked by a drop hammer.
   In the standard equipment is included full dual control, a fire extinguisher with spray leads to the carburettor, a compass, a turn and bank indicator, and an eight-day clock. Additionally ordered equipment can include navigation lights and an electric starter, with the necessary battery and wind-driven generator, and an artificial horizon and directional gyro in a special panel.


THE GENERAL AIRCRAFT CYGNET.
Figures for 130 h.p. Gipsy Major; the 159 h.p. Cirrus Major is alternative power unit.

Span 34ft. 6in. (10.5 m.)
Length 23ft. 3in. (7.09 m.)
Weight empty 1,450 lb. (657 kg.)
Pilot, passenger and baggage 494 lb. (224 kg.)
Fuel and oil 256 lb. (116 kg.)
All-up weight 2,200 lb. (998 kg.)
All-up weight (aerobatic) 950 lb. (884 kg.)
Wing loading (normal) 11.7 lb./sq. ft. (57.2 kg/sq. m.)
Power loading 16.1 lb./h.p. (7.23 kg/c.v.)
Maximum speed 135 m.p.h. (217 km/h.)
Cruising speed (70 per cent, power) 118 m.p.h. (190 km/h.)
Range 550 miles (885 km)
Stalling speed 46 m.p.h. (74 km/h.)
Landing range 60-85 m.p.h. (96-129 km./h.)
Initial rate of climb 800 ft. min. (244 m./min.)
Service ceiling 15,000ft. (4,580 m.)
Price £1,250
Makers: General Aircraft Ltd., London Air Park, Feltham, Middx.

Flight, September 1939

To-day's Light Aeroplanes

GENERAL AIRCRAFT

   INTERESTING, particularly because it has a tricycle undercarriage, and also because it is of all-metal stressed-skin construction, the General Aircraft Cygnet is now in production as a trainer or tourer. The designer's idea has been to produce a machine which will be virtually trouble-proof, both when flying and on the ground. The Cygnet is a low-wing side-by-side seater cabin machine with twin rudders. It is fully aerobatic and can be fitted either with a Gipsy Major or Cirrus Major engine. The figures given are for the latter.

Span 34ft. 6in.
Length 23ft. 3in.
Weight empty 1,475 lb.
All-up weight 2,200 lb.
Maximum speed 135 m.p.h.
Cruising speed 115 m.p.h.
Landing range 60-85 m.p.h.
Stalling speed 45 m.p.h.
Initial rate of climb 800 ft./mm
Range 445 miles.
Price £1,250.
Makers: General Aircraft, Ltd., Lon don Air Park, Feltham. Mddx.

Flight, November 1939

Britain's Civil Aircraft

GENERAL AIRCRAFT

   SINCE our last "Industry" number the development of the G.A. Cygnet (still Britain’s only all-metal light aircraft) has been completed. The Cygnet is a low-wing cantilever monoplane with an all-metal part-monocoque fuselage. A tricycle undercarriage and twin fins and rudders give great stability and ease of handling on the ground and in the air. Equipment includes split flaps and a special combined safety ignition switch and petrol cock. The cabin is covered by divided sliding hoods and seats two people side-by-side. A Gipsy Major or a Cirrus Major engine may be fitted.
   Data (with Cirrus Major engine.) are: Top speed, 135 m.p.h.; cruising speed, 115 m.p.h.; landing range, 60-85 m.p.h.; service ceiling 14,000ft. and cruising speed 445 miles. The span is 34ft. 3 1/2 in. and the all-up weight 2,200lb.