Flight, December 1922

THE "BRISTOL" THREE-SEATER, 100 H.P. BRISTOL LUCIFER ENGINE
A Machine for the Owner-Pilot

   SIMPLICITY of construction and a minimum of parts subject to wear are the special features of the new "Bristol" three-seater biplane which has just been produced by the Bristol Aeroplane Company, Ltd., of Filton, Bristol. In getting out the design of this machine, Mr. Reid, chief designer to the firm, endeavoured constantly to keep in mind the fact that, as the machine was intended for the owner-pilot, it was essential that everything which was likely to require attention should be as simple as possible, and that the number of parts that were at all likely to wear out should be reduced to an absolute minimum. Besides these desiderata, any such machine should, it was thought, be capable of carrying two passengers in addition to the pilot, and should be able to do so with the lowest horse-power consistent with a reasonably good performance. The outcome was the new Bristol three-seater, and in the following notes and illustrations we shall attempt to show the manner in which the designer attacked the problems he had set himself.
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General Design

   As regards the machine itself, the lines will be clear from the accompanying scale drawings and photographs. It is a heavily-staggered biplane, with only one pair of inter-plane struts on each side. The fuselage is fairly wide in proportion to its depth, and the two passengers are seated side-by-side in a cockpit aft of the pilot's. The latter, owing to the heavy stagger and the small obstruction formed by the "Lucifer" engine, has a particularly good view forward and downwards, while the close proximity of the two cockpits makes it possible for the passengers to carry on conversation with the pilot.
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Specification

   The main characteristics of the Bristol three-seater are as follows: Length over all, 23 ft. 6 ins.; span, 31 ft.; height, 8 ft. 10 ins.; wing area, 291 sq. ft.; weight, empty, 1,210 lbs; petrol (25 galls.) and oil (3 galls.), 215 lbs.; pilot, 180 lbs.; two passengers, 320 lbs.; luggage, 75 lbs.; total loaded weight, 2,000 lbs.; power loading, 20 lbs. /h.p.; wing loading, 7 lbs./sq. ft.; speed at ground level with full load, 90 m.p.h. (without passengers and luggage 93 m.p.h.); speed at 5,000 ft., with full load, 88 m.p.h. (without passengers and luggage, 91 m.p.h.); climb to 1,000 ft. with full load, 2 minutes; cruising speed, about 75 to 80 m.p.h.; landing speed, about 40 m.p.h.

Flight, July 1923

THE "BRISTOL" LUCIFER SCHOOL MACHINE

   THE new "Bristol" Lucifer school biplane is a strong and up-to-date machine, excellently suitable for instructional purposes, and so simple and strong in design and structure as to withstand hard service and constant use without much attention or depreciation. In addition to many special features, special attention must be drawn to the great reserve of power which has been provided for. From the figures given in the specification it will be seen that the total loaded weight is 1,700 lbs. The British Air Ministry's Certificate of Airworthiness, however, specifies that a load up to 2,140 lbs. may be carried.
   The 100 h.p. "Bristol" Lucifer engine is the power unit used. This is not only an engine of great reliability and simplicity of design, but as an engine of modern type it allows of the pupil gaining valuable experience of radial engines during the period of instruction. The consumption of this engine at cruising speed is extremely low, amounting to about 5 gallons of petrol and 2 pints of oil per hour. A starting handle is fitted to the Lucifer engine, so that the trouble, waste of time and danger of propeller swinging is entirely obviated. The petrol is provided from a scuttle tank fixed in front of the pilot, and is fed by simple gravity, a large and easily demountable filter being fitted. The unusual simplicity of the petrol and oil systems also calls for remark.
   In order to eliminate any possibility of danger from fire, steel fireproof bulkheads are fitted behind the engine, and all control connections pass through fireproof glands. Carburettor intakes are carried through the bottom side of the engine cowling, thus eliminating any possibility of the accumulation of petrol.
   The upper and lower wings are identical and interchangeable, and are of the single bay type. This arrangement is not only convenient, but reduces the spares which should be carried. The interplane struts, and those carrying the centre section, are of "N" formation, and require no trueing up.
   An oleo-steel spring chassis is fitted, the oleo plungers having a special type of tapered needle valve controlling the passage of the oil through the plunger and giving constant oil pressure throughout the stroke of 8 ins. The fitting of an oleo chassis, of course, helps considerably to reduce the risk of damage by reason of indifferent landings, whilst it also materially tends to lengthen the life of the machine.
   The tail incidence can be varied by a lever quadrant to trim the machine under all conditions of speed and load distribution.
   In the separate cockpits provided for pilot and pupils dual sets of controls are fitted, whilst the instruments are also duplicated. Communication between the cockpits is by telephone.
   The specification of this machine, which, as regards its general outline, resembles the Bristol taxiplane, is :- Span, 31 ft. 2 ins.; length, 24 ft. 4 ins.; height, 5 ft. 10 ins. Weight empty, 1,180 lbs.; pilot and pupil, 360 lbs.; petrol (15 galls.), 110 lbs.; oil (2 1/2 galls.), 25 lbs.; equipment, 25 lbs.; total weight, 1,700 lbs. Weight per h.p., 17 lbs.; weight per sq. ft., 6 lbs. Speed at ground level, 95 m.p.h.; speed at 6,500 ft., 92 m.p.h.; speed at 10,000 ft., 90 m.p.h. Climb to 1,000 ft., 1 min. 40 secs.; climb to 6,500 ft., 13 mins. Fuel consumption at cruising speed : petrol consumption, 5 g-p-h.; oil consumption, 2 pints/hour.