Flight, July 1932

The Spartan "Cruiser”

   THERE was a time, and not so very long ago, when it was a common thing to hear the complaint that a potential purchaser of aircraft could not obtain from a British firm anything between the light aeroplane two-seater of some 100 h.p. and the large commercial "air liner" of several hundred or even over 1,000 h.p. During the last two years things have changed radically, and there are now available to the purchaser of aircraft a very complete range of types and sizes, from the smallest single-seater through two-seaters, three-seaters, four-seaters and six-seaters, to the small, intermediate and large commercial aircraft. He would be a difficult man to please who could not find among them a type to suit his particular needs.
   A six-seater which has recently made its appearance, and which should find a large field of usefulness, is the new three-engined monoplane produced at Cowes by Spartan Aircraft, Ltd., and to be marketed as the Spartan "Cruiser." The close connection between Spartan Aircraft and Saunders-Roe, Ltd., is doubtless responsible for the similarity in structural features to Saro flying boats which the "Cruiser" exhibits. These features have by now been well tried out in such types as the Saro "Cutty Sark," "Windhover" and "Cloud" flying boats, and their application to a landplane type is to be regarded as very sound business.
   Fitted with three de Havilland "Gipsy III" inverted engines, the "Cruiser" carries, when equipped for passenger work, five passengers in addition to the pilot. This represents a power of 72 h.p. per paying passenger, which cannot be regarded as excessive in view of the good performance of the machine. When the cabin furnishings are removed and the "Cruiser" used as a freight carrier, the pay load becomes 1,000 lb., or 2.78 lb./h.p., for an endurance of 6 hours and a cruising range of approximately 700 miles. If the range is shortened, the pay load is, of course, correspondingly increased. As the machine has been designed to, and actually does, fly on any two of its three engines, it should cruise at a power expenditure low enough to ensure that engine failure should be almost unknown, and forced landings to all intents and purposes eliminated.
   The ratio of gross weight to tare weight is always worth examining, as it represents to some extent the "structural efficiency" of the aircraft. For the Spartan "Cruiser" as a passenger machine the ratio is 1.53, and for the freight-carrier it is 1.65. Both figures must be regarded as good, and indicate that considerable engineering skill has been brought to bear on the structural design.
   The aerodynamic efficiency also appears to be above the average. The Everling "High-speed Figure" has a value of 20.25, which points to a very low minimum drag coefficient. In appearance the "Cruiser" is certainly "clean," and the performance indicates that there is good scientific foundation for this impression.
   The cabin of the "Cruiser" is very well arranged, with comfortable seats along the sides, a good view through windows in the sides, and excellent lighting through the side windows and the roof lights.
   Fuselage.- The fuselage is of metal construction throughout, and follows closely in principle, although not, of course, in actual shape, the hulls of the "Saro" flying boats. A series of light frames give the fuselage, its transverse sections, while, the planking or covering is of "Alclad," stiffened by longitudinal corrugations spaced several inches apart. The planking is riveted to the frame flanges.
   Wing.- The cantilever monoplane wing is of all-wood construction, with two main spars of box section, having spruce flanges and three-ply sides. The wing ribs have spruce flanges and three-ply webs, and the covering is a three-ply skin which assists in providing torsional stiffness. Near the fuselage the wing covering is thickened and stiffened to form a walkway to the cabin door.
   Tail Unit.- The complete tail unit is a Duralumin structure covered with doped fabric. The rudder and elevators are provided with horn balances, and tail trimming is by a screw jack operated by a wheel in the pilot's cockpit.
   Power Plant.- The three De Havilland "Gipsy III" engines are mounted two in the wings and one in the nose of the fuselage. If desired, alternative types can be fitted provided they are of reasonably the same power and general type. The engine mountings are of steel tube construction, and the wing engines are faired carefully into the wing surface. As the central engine is rather high above the ground, it has been fitted with hand-turning gear. The outboard airscrews are within reach from the ground, and the outboard engines are therefore started by swinging the propellers.
   Fuel System.- There are two main petrol tanks, housed in the wing between the main spars, each tank being situated in the wing just behind its engine. Each tank has a capacity of 60 gallons (273 litres), which gives the machine an endurance of six hours at an economical cruising speed of 110 m.p.h. When the machine is used as a passenger carrier the tanks will not normally be filled up, but will contain enough fuel for about four hours' cruising. The tanks are interconnected with large balance pipes. Each engine is provided with a fuel pump which feeds direct to the carburettor. In the event of a pump failing, a cross-connection is arranged whereby the engine is supplied by another pump. Fuel contents gauges are fitted to each tank.
   Lubrication System.- The oil tanks are placed in the fairings behind each engine.
   Undercarriage.- The undercarriage is of the "split" type and has a wide track (10 ft.). The telescopic strut, which runs to the under-side of the front spar, is of the oil-cum-steel spring type. The bent axle hinges on the centre line of the bottom of the fuselage, in line with the front spar, while the radius rod runs to the rear spar.
   Controls.- Elevator and ailerons are operated by a hand wheel on a hinged column, while the rudder control is a parallel-motion, easily adjustable bar. From the pilot's controls to the various control surfaces the run through the machine is by rods and cables. Engine controls are conveniently placed, and operate through rods and torque shafts.
   Cabin Arrangement.- The fuselage is sufficiently wide to permit of placing the seats along the sides, with a gangway down the centre of the cabin. Four of the seats are placed between the wing spars, while the pilot's seat (on the port side) and that of the fifth passenger are in front of the leading edge of the wing. The windows in the sides of the cabin are of "Triplex," while those in the roof are of celluloid. The side windows are made to slide for ventilation purposes.
   Behind the cabin is a large stowage space for luggage.
   The main dimensions, areas, etc., are shown on the three-view general arrangement drawings.

Flight, November 1932

British Aircraft

Spartan Aircraft, Limited
Cowes, Isle of Wight

   ASSOCIATED with Saunders-Roe, Ltd., in that Sir Alliott V. Roe and Mr. John Lord are directors of both firms, Spartan Aircraft, Ltd., has developed from the firm originally started by Mr. O. E. Simonds, M.P. (who is now no longer connected with it), and several interesting types of aircraft for the private owner have been produced. Of these we have space to refer to but two.

The Spartan " Cruiser "

   This three-engined six-seater is a low-wing cantilever monoplane fitted with three de Havilland Gipsy III engines. It has an extremely comfortable cabin, and safety is ensured by the ability of the machine to fly on any two of its three engines. Structurally the "Cruiser" resembles the Saro flying boats in that it has an "Alclad"-covered fuselage and wooden wings. The data of the Spartan "Cruiser” are :-
   Length o.a. 39 ft. 2 in. (11,95 m.)
   Wing span 54 ft. 0 in. (16,45 m.)
   Wing area 436 sq. ft. (40,5 m".)
   Tare weight 3,400 lb. (1 542 kg.)
   Pilot 170 lb. (77 kg.)
   Five passengers 800 lb. (363 kg.)
   Fuel and oil 1,000 lb. (454 kg.)
   Gross weight 5,500 lb. (2 495 kg.)
   Maximum speed 135m.p.h. (217 km./h.)
   Cruising speed 110 m.p.h. (177 km./h.)
   Initial rate of climb 600 ft./min. (3,06 m./sec.)
   Ceiling 15,000 ft. (4 570 m.)
   Range 660 miles (1 062 km.)
   The machine can also be used as a freighter, when the pay load becomes 1,010 lb. (458 kg.), the range remaining the same as before.

Flight, November 1934

MODERN BRITISH AIRCRAFT REVIEWED

SPARTAN AIRCRAFT LTD.
One of the younger British aircraft firms, the Spartan company has a strong link with aviation history in that Sir Alliott Verdon-Roe and Mr. John Lord are on the board of directors.

   DESIGNED specially for "feeder line" work, the Spartan "Cruiser" is of "mixed" construction, the fuselage being built rather like the hull of a flying boat, which gives the machine the ability to spend, if necessary, long periods in the open, a feature which may be valuable, when operating a long way from a base. The machine is a three-engined low-wing cantilever monoplane, and the reserve power is such that height can be maintained with any one of the three engines stopped. Thus forced landings should be very rare occurrences.
   The fuselage is mainly of "Alclad" construction, with fore-and-aft corrugations externally to give stiffness to the covering. Panel beating has been avoided, so that repairs in the field can be made with a good degree of ease. The wings are of wood construction, the covering being plywood.
   Engines of 120-130 h.p. are suitable, the usual models being the ''Cirrus-Hermes IV" and the "Gipsy-Major." The two petrol tanks are housed in the wing, each having a capacity of 60 gallons (273 litres). If the machine is carrying more than six people, the tanks will not normally be filled quite full, but will contain sufficient fuel for four hours at a cruising speed of about 116 m.p.h. With full tanks and three passengers, the range can be extended to 620 miles.
   Triplex windows of large area give good lighting in the cabin, which may have seats for up to ten passengers, although the range is then fairly short. A more normal cabin layout is for five to six passengers, whose seats are very comfortable, with plenty of leg room. If desired, the pilot's compartment can be partitioned off from the main cabin.