Flight, September 1922
THE BOULTON AND PAUL P.9. BIPLANE
IT has been maintained that the aeroplane, at present, cannot hope to make much of a success in connection with regular air services within the British Isles, inasmuch as existing means of communication
could only be but slightly improved upon. Be this as it may, we are convinced that the aeroplane can be made to serve a very useful purpose here at home in another direction, i.e., as a "private" means of communication, either for business or pleasure. In fact, we are at a loss to understand why this side of aviation has not developed more than it has - if it can be said to have developed at all. Aerial taxi work, it is true, is becoming more popular, but the number of owner-pilots in this country is well under the half-dozen, in spite of the fact that "private" flying should be just the sort of thing that would appeal to the British sportsman. It is not that there are any great difficulties in the way to prevent the aeroplane being put to such a use - either for the owner-pilot or the owner with pilot-chauffeur, whilst it has been demonstrated on several occasions that the actual flying can be accomplished with as much safety as with motoring, and with but little, if any, extra cost. Neither is there any dearth of suitable machines, for during the last few years our constructors have produced several machines capable of giving very satisfactory results in this particular class of work. One of these machines, which has been more or less hiding its light under the proverbial bushel, is the Boulton and Paul P.9 which forms the subject of the accompanying illustrations and notes.
It will be remembered that there were two of these machines flying in the recent King's Cup Race round Britain, in which their performance, though not of a spectacular nature, was none the less worthy of notice. Piloted by C T. Holmes and J. C. Tennant respectively, these machines left Croydon within five minutes of each other, and kept a very steady course, within a few minutes of each other, throughout the race, Holmes averaging 69 m.p.h. and Tennant 68 m.p.h. for the outward journey, the averages for the homeward trips being 85 m.p.h. and 88 m.p.h. respectively. The machine shown in the accompanying illustrations is the one flown by Holmes, and is used by Mr. F. T. Courtney when he wants to "flip" anywhere in a hurry.
The P.9, which has been designed by Mr. J. D. North, is a two-seater tractor biplane of moderate dimensions, and is a plain, straightforward job both in design and construction. The outstanding features of this machine may be said to comprise low initial cost, low cost of running and maintenance and facility in handling both in the air and on the ground. It has a very good speed range and climb, and is nice and easy on the controls - which, together with its general stability, enables it to be flown for long periods without undue fatigue.
The main planes are of orthodox construction, and are equal span (27 ft. 6 ins.) top and bottom. They are made up of five sections, two in the lower and three in the upper. The lower sections are attached direct to the lower longerons of the fuselage, whilst the two outer sections of the top plane, are attached to a 5 ft. 6 in. centre section. A single pair of streamline (wood) struts separate top and bottom planes each side, and the centre section is carried above the fuselage by two N's of steel tube, the vertical members having streamline fairings. External wing bracing is by streamline wire, and the front and rear points of intersection of landing and lift wires are connected by a steel tube in order to reduce vibration. Both planes are set at a dihedral angle of 2 1/2°, and the angle of incidence is 2°. Ailerons are fitted to both top and bottom planes, the control cables from the fuselage being carried inside the lower wing behind the front spar.
The tail planes consist of a streamline-section horizontal stabilising plane, divided elevators, a vertical fin and balanced rudder. The horizontal plane can be adjusted as regards incidence by means of a lug having three holes arranged vertically, which receives a bracket on the rear spar of the tail plane, a bolt passing through one or other of the series of holes on the lug and bracket. This adjustment is indicated in one of our sketches.
The fuselage is of the conventional rectangular-section girder, wire-braced type, and the top longerons are not horizontal, but slope upwards towards the rear some 10°, so that the tail plane is slightly above the line of thrust. The comfort of the pilot and passenger has been specially considered, and each cockpit is roomy and fitted with special cane seats of ample proportions. The pilot's cockpit is at the rear, but dual control is provided for - the front control "stick" being easily removed when necessary - so that the machine can be flown from either cockpit. Instruments and engine controls are provided in both cockpits, and the engine revolution indicator is mounted outside the fuselage, forward of the front cockpit on the port side, where it may easily be read from either cockpit. Just behind the rear cockpit a fair-sized "boot" is formed under the turtle deck of the fuselage, for carrying suit-cases, etc. The cover for this is formed by a sheet-metal cowling with ventilators, which is held firmly in place by two wire cables passing over it, in a groove at each end, from one top longeron to the other. It is very easy to remove, as the cables are held taut by two wire strainers, which are quickly loosened by means of a tommy-pin, as shown in one of our sketches.
Fabric is employed for the covering of the fuselage except for the engine section and cockpit decks, where three-ply wood is used, and in the nose, which is of metal. The fuselage may easily be laid bare by means of a patent lacing device, similar to that employed, in furniture upholstery.
The engine, a 90 h.p. air-cooled Type IA R.A.F., is mounted direct on to the top longerons, and is partially enclosed by a metal cowling-cum air scoop. It drives, through the usual gearing with this type of engine, a four-bladed tractor screw 9 ft. 3 ins. diameter. The exhaust from the engine is discharged behind the rear cockpit, thus giving a silencing effect and a freedom from fumes.
An orthodox V-type landing chassis is fitted in which the tubular axle is sprung, by elastic cord, from the apex of the V - the cord being protected at the bottom by a metal strip. The front and rear tie-rods of the chassis struts are encased in a streamline metal fairing, and the axle lies in a groove formed in the top of this fairing. A stout tail skid is fitted, and in order to facilitate steering when on the ground, it is connected up to the rudder bar.
The principal characteristics of the P.9 are as follows :-
Span 27 ft. 6 ins
O.a. length 24 „ 8 ,,
O.a. height 10 ,, 0 ,,
Chord 5 „ 6 „
Gap 5 „ 6 ,,
Angle of incidence 2°
Dihedral angle 2 1/2°
Area of main planes 285 sq. ft.
Area of ailerons 38 „
Area of tail plane 24 ,,
Area of elevators 14 1/2 „
Area of fin 2 1/2 „
Area of rudder 8 3/4 „
Weight of machine empty 1,244 lbs.
Weight of machine (full load) 1,770 „
Weight per h.p. 17-7 „
Weight per sq. ft. 6-3 „
Speed (full load, 1,000 ft.) 104 m.p.h.
Climb (full load), in 8 1/2 mins 5,000 ft.
Ceiling 14,000 ft.
Range (full throttle) 3 hrs.
The P.6 on Mousehold airfield in 1918, with Mrs Flavie Dawson Pul, the Chairman's wife, in the rear cockpit, and J D North and Captain Frank Courtney alongside.
THE BOULTON AND PAUL "P 9"
THE BOULTON AND PAUL P.9. BIPLANE: Three-quarter rear view.
SOME DERBY MACHINES: Boulton and Paul P.9.
The Boulton and Paul P. 9 two-seater, with 90 h.p. R.A.F. engine.
The first true production P.9, 90 h.p. R.A.F.1A.
THE BOULTON AND PAUL P.9. BIPLANE: Three-quarter front view.
The End of a Far From Perfect Day: Squadron Leader Rea winning the Final, on the Boulton and Paul P.9, of the Bournemouth and District Business Houses Sweepstake.
At the Norwich Air Demonstration: The Mace-bearer hanging the chains of office on the Lord Mayor of Norwich, prior to a flight in the Boulton and Paul P.9. The Sheriff of Norwich and Mr. J. D. North appear amused at the proceedings.
AIR VISITORS TO LYMPNE: Mrs. Dawson Paul and Flying Officer A. V. Harvey at the Easter meeting with the Boulton and Paul P.9 biplane.
THE BOULTON AND PAUL P.9. BIPLANE: The 90 h.p. air-cooled R.A.F. engine fitted to this machine.
THE BOULTON AND PAUL P.9. BIPLANE: 1. The engine rev.-indicator is mounted in a streamline casing outside the fuselage, where it is clearly visible from both cockpits. 2. The simple adjustment for tailplane incidence. 3. The neat luggage boot behind the rear cockpit. Inset is the simple and effective fastener securing the cover in position. 4. The tail skid, which is connected up to the rudder bar to facilitate steering when taxying.
Boulton & Paul P.9. 90 hp R.A.F. 1a