General Aircraft Monospar ST-4 - ST-12
General Aircraft - Monospar ST-4 - ST-12 - 1932 - Великобритания
Страна: Великобритания
Год: 1932

Четырехместный легкий туристический и пассажирский самолет
General Aircraft ST-1, ST-2 и Monospar ST-3 - ST-12
Flight, April 1932
The Stieger ST. 4
Flight, November 1932
British Aircraft at the Paris Aero Show
Flight, November 1932
British Aircraft
Flight, July 1934
Flight, July 1934
Flight, January 1935

General Aircraft ST-1, ST-2 и Monospar ST-3 - ST-12

   Четырехместный прототип Monospar ST-4 представлял собой традиционный моноплан с неубираемым шасси с хвостовым колесом и силовой установкой из двух звездообразных моторов Pobjoy R мощностью по 85 л. с. За первой партией из пяти Monospar ST-4 последовало примерно 30 самолетов Monospar ST-4 II, минимально отличавшихся от первых пяти. В 1933 году появился прототип конструктивно близкого Monospar ST-6, имевший убираемое шасси. Построен один серийный Monospar ST-6, еще две машины модернизировали до уровня Monospar ST-6 II из варианта Monospar ST-4 II. В начале 1934 года разработан Monospar ST-10 с моторами Pobjoy Niagara мощностью по 90 л. с., с измененной топливной системой и улучшенной аэродинамикой. В 1934 году Monospar ST-10 выиграл гонки на Королевский кубок. Несмотря на удачную конструкцию, за прототипом был построен еще только один Monospar ST-10, далее собрали два очень похожих Monospar ST-11 с моторами de Havilland Gipsy Major, шасси с хвостовым колесом и с убираемыми вручную основными опорами.
   Финалом выпуска семейства ранних Monospar стали десять Monospar ST-12, которые отличались от ST-11 только неубираемым шасси.


   General Aircraft Monospar ST-12

   Тип: четырехместный легкий туристический и пассажирский самолет
   Силовая установка: два рядных ПД de Havilland Gipsy Major мощностью по 130 л. с. (97 кВт)
   Летные характеристики: максимальная скорость на оптимальной высоте 254 км/ч; крейсерская скорость на оптимальной высоте 229 км/ч; начальная скороподъемность 376 м/мин; практический потолок 6400 м; дальность полета 660 км
   Масса: пустого 835 кг; максимальная взлетная 1304 кг
   Размеры: размах крыла 12,24 м; длина 8,03 м; высота 2,39 м; площадь крыла 20,16 м'

Flight, April 1932

The Stieger ST. 4
Built by General Aircraft, Limited, of Croydon, and incorporating the Monospar System of Construction invented by Mr. H. J. Stieger, this machine is a four-seater fitted with two Pobjoy "R" Engines. That the Stieger System does give low structure weight appears to be proved by the fact that the ratio of gross weight to tare weight of the ST. 4 reaches the high value of 1-84 so that the machine carries as normal disposable load 84 per cent, of its own weight

   IN presenting to our readers an illustrated description of the Stieger ST-4 monoplane this week, we are faced with a slight difficulty arising out of the fact that, at the moment of writing, the machine is not entirely finished. In consequence it is not possible, for one thing, to publish photographs of the machine in its completed form, and, secondly, actual performance figures, etc., are not available. However, as the machine is certainly an unusually interesting one, both from the designer's and from the user's point of view, we have thought that the best procedure would be to deal with the ST.4 this week mainly from the structural aspect, leaving the subject of the practical or operational features for a subsequent article. In order, however, to give our readers a slightly better idea of how the ST.4 will appear when finished, we have had blocks made of some photographs of a scale model, and these will be found in the description which follows.
   Before turning our attention to the structural details of the ST.4 it may be of assistance to our readers if we mention quite briefly that the machine is designed as a four-seater twin-engined monoplane, ability to maintain height with one engine out of action having been kept prominently in view during design. By clean aerodynamic design, low structure weight, and light engines, it is thought that this desirable quality has been attained, although definite proof in the form of actual test flights must still be awaited. A cruising speed of approximately 115 m.p.h. (185 km./h.) has been aimed at.

Power Plant

   The two Pobjoy "R" engines are mounted en parte a faux from the single wing spar. Two horizontal vees whose apices meet on spar and engine frame in such a way as to form a double wedge carry the engine mounting proper, which consists of steel tubes so arranged as to give triangulation. The whole engine attachment is free to swing laterally around the vertical hinges on the spar, but are prevented from doing so by the continuation of the leading edge which crosses the engine mounting framework.
   The petrol tanks are mounted inside the wing, and straddle the wing spar. Each tank has a capacity of 21 gallons, and is made of tinned sheet steel, so that in the event of a leak during operation, anyone who can use a soldering iron can make the repair. The tanks are actually in the middle wing portions, so that to permit folding of the wings a length of flexible tubing connects with the carburetters. This placing of the petrol tanks does not give sufficient ''head'' to produce gravity feed when the machine is climbing and accelerating, and the petrol system therefore includes two A.C. pumps, the system being so arranged that either pump can supply either or both engines. All the engine controls are of the Arens remote type.


   By making use of the new telescopic legs marketed recently by Aircraft Components Company (Mr. G. H. Dowty), it has been possible to design a very neat undercarriage for the ST.4. The telescopic legs incorporate coil springs for the actual aircraft load, and an oleo gear for checking bouncing. A feature of these legs is the exceedingly compact arrangement, which makes it possible to get the whole shock-absorbing mechanism into a circular tube of very small outside diameter. Each undercarriage tripod is completed by an axle and a radius rod, and further to reduce drag the wheels are partly enclosed in "spats." The wheels are Dunlops (19 x 7) of the low-pressure type (wired), and Bendix brakes are fitted. The brakes are operated by a lever centrally placed in the cabin, between the two "joy sticks." The lever applies both brakes, and for steering on the ground use is made of the fact that the engines are placed on the wings. A castoring tail wheel is fitted, the tyre being a Goodyear, 12 x 5.
   It is not our intention to deal this week with the cabin accommodation of the ST.4 in great detail. It will suffice if we state that seats for two pilots are placed in front, with a complete set of dual controls placed side by side, while the passengers are situated behind the wing spar, far enough to have very ample leg room. The seats are arranged side by side, and there is space for yet another seat on the wing spar, so that the machine could quite well accommodate five.
   The flying controls are of orthodox type, with dual "joy sticks" and parallel-motion rudder pedals. The brake lever is, as already mentioned, located centrally between the two "joy sticks," where it is within reach from either seat. The instrument board contains Smith's instruments exclusively, but is not the standard Smith board, the width of the cabin being rather greater than in most machines and the available space therefore of somewhat different proportions. A sliding map tray disappears into the instrument board when not in use.
   It is not often that one has cause to complain that a cabin is too light. In the ST.4, however, the windows in side and roof are so large that it seems quite possible that tinted blinds will have to be provided, especially if the machine is to be used outside Great Britain.
   Owing to the position of the engines in relation to the fuselage, the view from the front seats is quite remarkably good. From the passengers' seats the wing obscures the view somewhat, but even so quite a good deal of ground can be seen, and, of course, the whole upper hemisphere.
   Access to the cabin is by doors formed of combined fuselage sides and roof, the hinges being along a diagonal line on the fuselage side. Steps are provided on the trailing edge of the wing roots, although the wing is not very high above the ground when the machine is standing with its tail down. The wing root structure has been made strong enough to withstand walking on. The cabin floor is of plywood, carried on transverse fuselage members of I-section, built up from two channels of duralumin placed back to back. Light fore-and-aft stringers give the floor the necessary stiffness in the spaces between floor bearers. A comfortable feature of the cabin is that the floor is perfectly flat, i.e., there is no curvature in it in any direction. All controls, etc., pass under the floor, which is left perfectly clear.

Flight, November 1932

British Aircraft at the Paris Aero Show

General Aircraft, Limited

   THAT one of the youngest of British aircraft firms should have achieved such success with its first machine as to be in a position to exhibit at a Paris Aero Show is cause for satisfaction. General Aircraft, Ltd., has been founded by Mr. H. J. Stieger and his associates to design and build machines incorporating the Stieger monospar principle of wing construction. The machine to be exhibited at Paris will be the first type to be produced by the firm, i.e., the Monospar ST.4. This is a four-seater aircraft intended for the private owner, and is fitted with two Pobjoy "R" engines.
   The fuselage is of unusual construction in that the rear portion has a sort of monospar backbone, torsionally stiffened by pyramid bracing. The cantilever wing has the Stieger monospar construction in which a single spar is in itself strong enough to carry the pure bending loads, but is enabled to withstand torsional stresses by a system of spiral wire bracing known as pyramid bracing. The whole machine is extremely light and has an excellent ratio of gross to tare weight.
   The cabin is so laid out that one passenger sits next to the pilot in front, while the other two occupy a side-by-side seat at the back. A large luggage locker is behind the rear seat. From the pilot's seat a quite remarkably good view is obtained in all directions which matter, the absence of an engine in the nose of the fuselage making this possible, as above photograph shows.
   The main data of the Monospar ST.4 are as follows :-
   Length o.a. 26 ft. 4 in. (8,03 m.)
   Wing span 40 ft. 2 in. (12,24 m.)
   Wing area 219 sq. ft. (20,35 m.2)
   Tare weight 1,300 lb. (590 kg.)
   Disposable load 1,000 lb. (454 kg.)
   Gross weight 2,300 lb. (1 043 kg.)
   Maximum speed 132 m.p.h. (212 km./h.)
   Cruising speed 112-115 m.p.h. (180-185 km./h.)
   Range 500 miles (805 km.)
   Landing speed 46 m.p.h. (74 km./h.)
   Take-off run (still air) 84 vards (77 m.) in 7 seconds.
   Initial rate of climb 900ft./min. (4,58 m./sec.)
   Maximum ceiling 18,000 ft. (5 486 m.)
   Landing run (still air) 110 yeards (101 m.)
   The machine is capable of maintaining height on one engine, and of carrying out normal manoeuvres with one engine out of action.

Flight, November 1932

British Aircraft

General Aircraft, Limited
Air Port of London, Croydon, Surrey

   AS General Aircraft, Ltd., are exhibiting one of their Monospar St.4 monoplanes at the Paris Aero Show, and this is dealt with elsewhere in this issue, it may be preferable to deal here with the Monospar principle of wing construction rather than with any particular machine in which this system is used.
   The single-spar wing was invented by Mr. H. J. Stieger, who is now managing director and chief designer of the Monospar Company and of General Aircraft, Ltd. Mr. Stieger is a Swiss by birth, but most of his aeronautical career has been spent in England, and the headquarters of his companies are in London.
   The general principle of the Stieger Monospar wing is simplicity itself, and consists, briefly explained, of a single main spar, which may be of metal or wood construction and of any form desired, such as a box spar, an I-section beam, or any other type which will support the bending loads arising from the lift on the wing. This single spar is designed to resist bending loads only, and would be very weak in torsion. The torsional strength of a Monospar wing is supplied by a system of bracing, which may be in the form of wires, cables, tie rods, or any other member capable of resisting tension loads. This system has been termed "pyramid" bracing because it is supported at leading and trailing edges on suitable struts, the ends of which form supports for the apices of the four wires meeting at that point. Where the wires cross over the spar they are attached to the top and bottom flanges of the spar by substantial steel wiring plates.
   The "pyramid bracing" of a Monospar wing may be pictured as two spirals wrapped around the wing in opposite directions, one set resisting loads due to a forward movement of the centre of pressure and the other a rearward movement.
   It will be realised that ultimately the inner ends of the pyramid bracing must be attached to the fuselage. Also that the plain pyramid bracing is not capable of taking drag and anti-drag loads. Separate wires parallel with the wing span can be used as drag and anti-drag members, but it is also possible to make the leading edge itself strong enough to serve either as the drag wire, and to have an anti-drag wire at the rear ends of the pyramid struts, or even to make the leading edge strong enough in comparison to take both drag and anti-drag loads.
   A considerably lighter wing structure is claimed to be possible by using Monospar construction, and some time ago a Monospar wing was built for a Fokker F.VII-3m. monoplane to test out the theory. The designers claim that on the Fokker wing a weight saving of 39 per cent, was made, which resulted in an increase of 37 per cent, in pay load. That large wing is still undergoing official tests for the British Air Ministry.

Flight, July 1934



   Being built on the single-spar principle, the General Aircraft machines have naturally created a large amount of interest since they were first placed upon the market. The "S.T.10 " is the latest version of the "S.T.4," which was described in Flight of April 22, 1932. In its essential features it remains the same - that is to say, the wing has a single girder spar built up from drawn channel-section strip steel and braced for torsional rigidity by a system of king posts and bracing wires. The fuselage consists of two portions. The front portion, carrying the cabin and the wing root fittings, is a normal steel tube, rigidly braced structure, but the rear portion is built up around a girder possessing much the same characteristics as the wing spar. The "S.T.10" has, however, two Pobjoy "Niagara" engines of 90 h.p. each, as against the Pobjoy "R." type of engine, and also there are certain structural alterations which have been proved desirable since the machine was produced. For example, the nose of the fuselage has been made cleaner by sweeping it up in a straight line over the windscreen. The fuselage itself has been increased slightly, both in width and in depth, although the drag has been kept down by clean design. The fuel, instead of being housed in the wing roots, is now in a tank between the spars under the floor of the cabin, thus giving a slightly better weight distribution.
   The flying controls have been altered considerably, and now consist of a central built-up column having a swivelling head, whereby the control may be used by either occupant of the front seats. The prototype of this machine had a screwed-in front locking pin, which had to be taken out before the wing could be folded. This has now been replaced by pins working on a lever, with a consequent decrease of the time taken for folding. The wheel brakes now fitted are the latest differentially operated Palmer hydraulic type, and we understand that excellent results have been obtained. The machine in the race will be flown by Flt. Lt. H. M. Schofield, and will not have a retractable undercarriage, although the fittings allow this to be substituted for the fixed undercarriage when desired. When this is done, the machine becomes the "S.T.11."


   Span 40 ft. 2 in. (12,2 m)
   Aspect ratio 7.4:3 to 1
   Wing area 217 sq. ft. (20,2 m')
   Gross weight 2,550 lb. (1 156,7 kg)
   Tare weight 1,470 lb. (666,8 kg)
   Wing loading 11.75 lb./sq. ft. (57.4 kg/m2)
   Power loading 14.16 lb./h.p. (6,4 kg/hp)

Flight, July 1934

New Ideas About Fuselage Design Have Greatly Increased the Speed of This Latest Monospar Aeroplane and Enabled General Aircraft to Win the King's Cup

   AERODYNAMIC interference and air stream flow over the fuselage are two factors which make an aeroplane designer's life difficult. Now that high-speed commercial aeroplanes are being built which must, if they are to be worth anything to operators, get their performance from a comparatively low total horse-power, both subjects are receiving great attention throughout the world. Mr. H. J. Stieger, Managing Director of General Aircraft, Ltd., and the designer of the Monospar series of aeroplanes, formulated certain theories about body shape some little while ago and later these were corroborated by the findings of a Russian scientist. Encouraged by the success of his first machine, Mr. Stieger has incorporated these ideas in the "S.T.10," with the result that the performance was greater than the handicappers expected and the King's Cup came into his company's possession.
   It is interesting to learn that although the cross-section of the fuselage has been increased by two square feet in the "S.T.10," the altered shape of the nose giving a better entry, particularly underneath, has resulted in an increase in speed of over 10 m.p.h. Part of this increase is due to an alteration in the fore and aft attitude of the machine during flight. These facts make the machine doubly interesting because it is one of the select few built for the ordinary user wherein the designer's ideas have resulted in beating the handicappers in a race.
   The "S.T.10," as it flew in the race, has a fixed undercarriage, but nevertheless the two Pobjoy "Niagara" engines of only 90 h.p. each pull it through the air at 144 m.p.h. That speed, for only 45 h.p. per person, is no mean achievement, but the performance of the "S.T.11" will be even more spectacular. This will be the model with the retractable undercarriage and it will have an easy cruising speed of 150 m.p.h.
   The cabin of both models is very light and airy and the windows, which extend right to the rear behind the passengers' seats, completely obviate any feeling the occupants might otherwise have of being shut in. Being a two-engined machine the outlook for the pilot is admirable, and it is worth noting that both Flt. Lt. Schofield and Mr. Gardner, who was flying an "S.T.6," were able to get through the bad weather which held up other people.
   Structurally, the "S.T.10" does not differ very greatly from the "S.T.4," which was described in Flight for April 22, 1932.
   The Monospar arrangement of both the wings and the fuselage has, of course, been retained, but the latest model has a considerably deeper cabin with the passengers sitting higher in it, and the fuel is now carried in a tank beneath the floor. As much as possible of the whole structure is built up from steel tubes or drawn steel channels of various sections, and, naturally, the whole is assembled in jigs, so that replacement of any part is a simple matter. As our sketches show, the front portion of the fuselage is rather like a "hip-bath" of steel tubes. This forms the cabin and carries both the wings and the undercarriage. The rear portion is built up round a Monospar girder braced with kingpost and wire stays for torsional rigidity. The wing stubs are structures carrying the engines and the outer struts of the undercarriage, and form the fixed hinge for the outer sections of the wings, which fold inwards when the trailing edge flaps of the stubs are folded up.
   The wings themselves are mainly built of steel and are covered with doped fabric. The single spar is a deep girder built up from strip steel drawn into channel section and tapered heavily. It is a pure cantilever and is pin-jointed, for folding, to the spar which runs right through the fuselage and wing stubs. The leading edge is locked to the triangulated structure forming the front of the wing stub and carrying the engine mounting, when the wing is extended.
   Throughout the whole machine duralumin and aluminium are used wherever weight can be saved without a decrease in strength. For example, the whole of the cabin top is of light alloy, as is the structure over the rear portion of the fuselage which carries the fabric from behind the cabin to the tail.
   Welding is not used and all joints are either riveted or bolted. This, of course, means more work in some ways, but Mr. Stieger maintains that strength for strength a lighter structure can be built with joints of this kind.

Flight, January 1935

The "S.T.12" with two 130 h.p. "Gipsy Major" Engines: A New Type in the Well-known Monospar Range, Offering a Higher All-round Performance

   IN the normal course of events, when a manufacturer produces some piece of apparatus - a car, aeroplane or fountain pen, for example - people rapidly become used to it, and then want something better. Ever since they were first brought out, the General Aircraft Company's Monospar aeroplanes have been improved from time to time, but without radical departure from their original sound layout; this design was so obviously what was wanted that there has been no demand for alterations.
   The "S.T.12" has been produced in response to those pilots who wanted a Monospar type with a better climb, a higher cruising speed, and an outstanding performance on one engine.

The Engine Mountings

   A study of the table of performance figures on page 13 will show that these requirements have been met most successfully. The two 130 h.p. "Gipsy Major" engines have been mounted in a similar fashion to the Pobjoy engines previously used; that is to say, they are carried on steel-tube mountings projecting from the wing spars at a point in the stub wing just forward of the hinge which allows the wings to be folded. The undercarriage forms part of the mounting structure, and is, in effect, the retractable undercarriage of the "S.T 11," but permanently extended. It is covered with a "trouser" form of fairing.
   Already a considerable amount of flying has been done with this new type, and it has been found that not only are the take-off and climb fully up to expectations, but that the good control when flying on one engine - a characteristic for which the earlier Monospar models were famed - has been retained. In other respects the "S.T.12" is similar to the "S.T.10," which was fully described after it had won the King's Cup Race last year in such a spectacular fashion (see description in Flight of July 19, 1934).
   The front windscreen has been modified, and, instead of the flat panes of safety glass previously used, there is now a single large curved sheet of "Rhodoid," a form of celluloid; this should not only give the pilot a better outlook but should obviate both the collection of water and reflection from internal and external lights. Lightly loaded, the "S.T.12" has a climb of 1,800 ft. /min., and an amusing story is told of an occasion upon which it outclimbed three R.A.F. single-seater fighters, although it must be admitted that these were of an obsolescent type.
   The fitting of the “Gipsy Major” engines does not in any way alter the handiness of the wing folding, nor has it resulted in the necessity for changing the interior layout of the cabin. The latest throw-over type of wheel control is used.
GENERAL AIRCRAFT CO.'S ST4: A similar machine (two Pobjoy engines) will be exhibited at the Paris Aero Show.
UNRESTRICTED OUTLOOK: Our photograph emphasises the fact that the pilot of a Monospar never suffers from being unable to see in any direction
LONDON-ZURICH-LONDON: The first long flight of the first Stieger S.T.4 Monospar machine after getting its Certificate of Airworthiness was to Zurich during the meeting held there. In Switzerland and Italy the machine aroused a great deal of interest. Flt. Lt. Schofield. who piloted the machine, reports that he had rjo trouble whatever, and the two Pobjoy "R" engines ran faultlessly. Mr. Schofield was kept busy, while at Zurich, demonstrating the S.T.4. It was unfortunate that his visit took place too late for him to take part in the international contests.
LONDON'S NEWEST AIRPORT: A Monospar and two "Moths" arriving above the recently opened aerodrome and seaplane base at Gravesend.
THE ST. 4: The first of the General Aircraft Monospar machines has now been repaired after its recent mishap, when it collided with a fence and damaged a wing tip. The machine has already flown for more than 5 hours and is said to handle very well, while the landing speed is remarkably low.
This Monospar ST.4, G-ACEW, named Inverness was Highland Airways' first aeroplane and remained with the company until 1937.
THE START: Capt. Dancy "dropping the flag" for Miss Crossley who flew her "Swift" into third place in the Heston-Cardiff Race. Next to her in the line, Mr. Jackaman's Monospar looked very resplendent.
Mr. A. C. M. Jackaman's newly acquired "Monospar." The head-light aperture is clearly visible in the nose of the fuselage.
SOME BRITISH VISITORS AT BUC: Mr. Graham Mackinnon (right) with his pilot, George Reynolds (left) and Monospar.
The Monospar, designed and manufactured by General Aircraft Ltd. of Croydon, meets the modern demand for an economical twin-engined light four-seater with a good performance, a good view and saloon car comfort for pilot and passenger. All Monospar productions are, of course, Doped with Cellon.
RISING WITH THE SUN: A "Monospar" (two Pobjoys) flying over the Asahi Aerodrome at Osaka, machine is used by the Asahi Newspaper Co. for service between Japan and Manchuria.
Данный Monospar ST-4 был поставлен покупателю из Швейцарии в ноябре 1932 года. Затем самолет перепродавался дважды и в конечном итоге оказался во Франции.
MONOSPAR CARRIES BOURBON PRINCE: Seated on the right of Capt. R. Stocken in the Monospar, is Prince Sixte de Bourbon-Parme, who, accompanied by Le Comte de Beam (in rear seat) returned to Paris in this machine on December 22, after lecturing before the Royal Geographical Society in London.
THE THIRTEENTH: Mr. Jackaman's Monospar was No. 13 in the thirteenth King's Cup Race, and he was "eliminated" on July 13th. He is seen here checking the "revs." of his Pobjoy engines.
MONOSPARS IN BRAZIL: Two Monospar ST.4 machines operated by Viacao Aerea Sao Paulo (VASP) of Brazil.
Highland Airways - now part of the Scottish Airways system - pioneered the Orkney service. Here is the old Monospar S.T.4 as it was delivered for the Inverness-Kirkwall run in April, 1933; Capt. E. E. Fresson is on the left.
IN ROME: A cheerful group before the Monospar in Rome. Mr. H. J. Stieger is fourth from the right and Flt. Lt. Schofield third from the left.
A group of onlookers gaze at part of the PSIOW fleet at Portsmouth in 1937. The Westland Wessex G-ARVB was specially built for the airline’s high density routes, and metal tubing replaced the wooden members in the wings. The General Aircraft Monospar ST-4 survived in Australia until 1954, but D.H.60 G-AAAG crashed into the Solent on November 1, 1934, after a low level stall, the two occupants being drowned.
The scene at Ramsgate Airport on August 3, 1936. In the foreground is Ramsgate Airport's Short Scion G-ADDV; behind that is another Scion, G-ACUZ, Monospar ST-6 G-ACGI, a Swallow, Aeronca C-3, a row of Fleas and the Cierva C.30 autogyro.
THE LATEST VERSION: General Aircraft Co.'s S.T.10 has two 90-h.p. Pobjoy "Niagara" engines.
Types of Machine in the King's Cup Race (5) Monospar "S.T.10," two Pobjoy "Niagara" 90 h.p. engines.
LANDING, The Monospar "S.T.10" landing at Hatfield. The new, complete cowling of the two Pobjoy engines is neat and clean.
THE WINNER: Flt. Lt. Schofleld crossing the finishing line in his Monospar "S.T.10" (two Pobjoy 90 h.p. "Niagara" engines) after covering the course of the Final at more than 135 m.p.h.
IN THE OFFICE: Mr. H. J. Stieger, designer of the "S.T.10," and Managing Director of General Aircraft Ltd., is here standing In the cockpit of the machine before the race started. Seated is Flt. Lt. H. M. Schofield, General Manager and Chief Pilot of the company. He flew the "S.T.10" throughout the race.
PLEASED: Flt. Lt. H. M. Schofleld carried as passenger throughout the race Mr. H. J. Stieger, the designer of the machine and the inventor of the Monospar system of wing construction.
The Portsmouth, Southsea and Isle of Wight Aviation Ltd. fleet at Portsmouth in 1937. Four Airspeed Couriers are lined up on the left and a Fox Moth and two Monospars stand behind them. The ST-10 G-ACTS won the 1934 King’s Cup Air Race. It was a prototype and never went into production, but served with PSIOW on the Ryde Ferry.
"Monospar" (2 Pobjoy) four seater.
FOR AUSTRALIA: A photograph taken at Croydon of the latest Monospar ST.11, which, as already recorded in Flight, is being delivered to the Australian Government. This machine has large fuel tanks giving a range of 1,100 miles.
Monospars on the tarmac outside the General Aircraft works at Croydon. G-ACTS was an ST-10, built in 1934 and flown with Portsmouth, Southsea & Isle of Wight Aviation Ltd. The Croydon factory closed down in 1933 and GA moved to better premises at Hanworth the following year.
POBJOY "NIAGARA" ENGINES FLYING: Mr. C. Gardner has had two of the Pobjoy "Niagara" engines put in his Monospar, and is now carrying out test flights for the makers.
VIEW OF THE LATEST "MONOSPAR" TYPE S.T., showing the undercarriage retracted and also the new type engine cowling. The re-modelled windscreen should also be noted. These modifications have improved the performance of this machine quite considerably.
The only entry of its type, the Monospar S.T.12 (two Gipsy Majors), may carry on the tradition of last year's winner. The pilot is O. G. E. Roberts.
Four/five-seater twins of two generations are housed together at Bankstown, Sydney. Monospar ST-12, VH-UTH (c/n. 36), owned by L. G. Taylor, was delivered in 1935, while the Peel River Mining Co.'s Apache, VH-PKA, is of 1957 vintage.
Seen here with its racing number “45” for the Brisbane-Adelaide Air Race, General Aircraft Monospar VH-UTK (c/n 38) was borrowed from Airlines of Australia, the manufacturer also being a subsidiary of the British Pacific Trust. The figure in black repairing the nose is almost certainly qualified engineer and pilot May Bradford.
A General Aircraft Monospar ST-12 of unknown origin, in use during the war as a communications aircraft with the Nationalist Air Force. This aircraft may well be the ST-12 ferried to the Ministerio Hacienda, Spain, as EC-W43. It was one of six ST-12s exported about 1935, and was powered by two 130 h.p. de Havilland Gipsy Majors.
FOR AUSTRALIA: Last week the first pair of a series of Monospar machines ordered by an Australian company where "christened" at Hanworth. This photograph, taken by a Flight photographer, shows the S.T.12, one of the types on order, from an angle which clearly illustrates the characteristic wing-form.
A pleasant general impression in Saturday's intermittent sunshine. In the air is the Monospar S.T.12.
O. G. E. Roberts (right), pilot of the Monospar, checks his course calculations before tne Eliminating Contest.
Ivy and Jason pose for a photograph in the cabin of Monospar VH-UTK at the time of the Brisbane-Adelaide Centenary Air Race. It is probable the pair were already romantically involved, but the official line was that Hassard was accompanying Ivy as a navigator and radio operator. Note Ivy’s bespoke khaki flying jacket.
Ivy posing with a Monospar, presumably VH-UTK, in 1936. The aircraft was a de Havilland Gipsy Major-powered ST-12; after returning to service on Airlines of Australia’s Brisbane-Townsville route following Ivy and Jason’s participation in the centenary race, it was destroyed by fire on the ground at Mackay on July 1, 1938.
Mrs. S. M. BRUCE, the wife of the Australian High Commissioner, christens one of the Monospar S.T.12's which are bound for the Commonwealth. In the group may also be seen the Rt. Hon. S. M. Bruce, Mr. and Mrs. Gordon England, Mr. Whitney Straight, Mr. H. J. Steiger (Monospar technical director), and Flt.-Lt. H. M. Schofield.
The civil side: A number of factories were opened to the public, and this is a scene in the General Aircraft Company's works at Hanworth, with interested visitors examining a Monospar S.T.12 destined for the Heston - Croydon "ferry" service.
SIDE VIEW OF THE ST.4: The single girder of the fuselage primary structure can be clearly seen. Note also swivelling tail wheel. A corresponding view of the scale model is at the top of the page.
THE BUSINESS PORTION OF THE ST.4: The Pobjoy "R" engines drive Fairey metal airscrews. Note the slimness of the Dowty telescopic legs. The cabin is reached via hinged combined doors and roof.
THE PORT POBJOY Some wing root details may also be seen.
ENGINE SUPPORT: The engine plate proper is carried on four tubes forming a "double wedge," and prevented by a continuation of the leading edge from swinging laterally. Note the oil tank and cooler.
THE POSTERIOR ASPECT: This view, taken from immediately behind, shows wing construction, etc., rather well. Note the placing of the petrol tanks in the wings. The top boom of the wing spar continues right across the fuselage.
REAR END OF THE FUSELAGE: Details included are the tail-trimming gear and the castoring tail wheel.
THE FUSELAGE GIRDER: The photograph should be examined in conjunction with the sketches on the next page.
THE SINGLE SPAR: The photograph shows the general arrangement of the shear members
"THE NIGHT PILOT'S EYES" fitted in the cabin of a "MONOSPAR" (General Aircraft Ltd.)
A neat ventilator built into one of the cabin windows of the Monospar,
LESSENING HEAD RESISTANCE. That the new monospar (2 Pobjoys) will be a clean aircraft is here very evident. The cut away wing-root, though by no means a new idea, has not been used of recent years and should, particularly in a twin-engined aircraft of this type, ensure effectiveness of the tail controls at all speeds. Even with the tail on the ground the pilot's view will, in this design, be completely unrestricted.
SAFETY, COMFORT AND EFFICIENCY. Attention to detail design is undoubtedly the secret of successful aircraft. It will be seen that the aircraft being turned out by General Aircraft, Ltd., of Croydon, embody very definite ideas on this subject. Mr. H. J. Stieger is one of the younger generation of designers who are not afraid of incorporating ideas which are radically different from those of accepted practice. The Monospar aircraft appear to be streamlined to the limit, while at the same time providing a perfect view for the pilot, together with immunity from forced landings by virtue of the two Pobjoy engines which are used. The full four-seater fuselage does not appear bulky, yet ample room is provided for the passengers. For commercial work where a large number of passengers is not required this machine should have a wide field of usefulness.
AS IT WILL APPEAR: A composite photograph of a scale model of the ST.4. The actual cowling over the Pobjoy engines will not be of the totally-enclosing type.
THE FUSELAGE GIRDER: Sketch shows the details of the girder and the torsion bracing, etc.
THE PRIMARY STRUCTURE OF THE FUSELAGE: The key diagram gives the locations of the details. The torsion bracing has been omitted.
ON THE ST.4: The trailing portion of the wing roots hinges up alongside the fuselage to allow of folding the wings. It is in this portion of the wing that the lifting of the trailing edge occurs, the object being to reduce interference drag. A step on the trailing edge facilitates getting into and out of the cabin.
TAILPLANE AND AILERON: The tailplane is shown in the upper photograph and an aileron in the lower. Details of the various members are shown on the right.
THE SINGLE SPAR: The sketches illustrate structural details. The small sketch at the bottom shows the rib-supporting brackets.
A MASS BALANCE: To conform with Air Ministry requirements, ailerons must have a mass balance. This is how it is fitted to the S.T.10.
S.T.10 FUSELAGE DETAILS: The centre portion of the "S.T.10's" fuselage is built up as a unit of steel tubes. The details show how the girder forming the rear portion is made from drawn sections.
CONSTRUCTIONAL DETAILS of the Monospar "S.T.10." The lettering shows the parts of the main structure to which the small sketches refer. This new model has only one door to the cabin but the whole top opens up as well, making getting in and out a very simple and easy matter.
Another British gear which retracts longitudinally is that on the Monospar S.T.11.
In this view are shown the essential features of the structure which combines the engine mounting and the undercarriage. Both sides are identical. The shock-absorbing rubber blocks are carried in each of the rectangular undercarriage legs.
Why "Chassis-borne"? This phrase is aptly employed to signify a structure similar to that in the motor car, or to the keel of a ship; a strong primary arrangement of braced girders (the Monospar system), surrounded by a light superstructure. The superstructure gives high aerodynamic efficiency and an outstanding propensity for cheap repairs by not necessarily fully skilled or licenced engineers, and provides for easy modification to suit a multitude of purposes; it also protects the primary structure from many of the expensive and serious accidents which frequently occur on the best regulated of aerodromes.
One of the Gipsy Major high-compression engines of the Monospar S.T.12, the only twin-motored machine in the race.
General Aircraft ST.4 2 Pobjoy "R" Engines
Monospar "S.T.10" 2 Pobjoy (90 h.p.) "Niagara" Engines
Monospar "S.T.12" Two 130 h.p. "Gipsy Major" Engines