Flight, March 1938

British light aircraft

ARPIN

   WITHIN a lew weeks, the Arpin pusher, which was first described in Flight of November 25 last year, should be making its test flights. The machine is primarily interesting because the designer has striven for safety and comfort rather than for sheer performance. It is, too, designed around a tri­cycle undercarriage, and, though built of wood, to some degree resembles the .American Stearman-Hammond. The engine fitted to the prototype is a 68 h.p. British Salmson. The two occupants are seated in tandem.

   SPECIFICATION: Span. 31.ft. 6in.; length, 23ft. 5m.; all-up weight, 1,260 lb., weight empty, 740 lb.; maximum speed, 108 m.p.h.; cruising speed, 95 m.p.h.; landing speed. 38 m.p.h.; initial rate of climb. 680ft./min.; range, 475 miles. Makers: M. B. Arpin and Co., Longford, West Drayton, Middlesex.

Flight, May 1938

COMBINED VIRTUES
The Arpin Monoplane Makes Its Public Appearance : A New Pusher Type with a Tricycle Undercarriage

   TOWARDS the end of last year we gave some details and published a scale drawing of a new private-owner type which was being made by M. B. Arpin and Co., of Long­ford, West Drayton, Middlesex. During the last few weeks the prototype has been nearing completion, the final assembly and finishing work being done at Rollasons at Han­worth, and the machine came out into the open in public for the first time at the R.Ac.S. Garden Party.
   For a prototype the Arpin A.1 monoplane is certainly very well made and finished. A great deal of attention has been paid to detail work and such items as control leads are of a sturdy and workmanlike type such as one expects to see only on larger machines. Apart from what is still an unconventional general layout, the structure is comparatively orthodox. The wing is of plywood-stressed skin with a single spar, which, though in three pieces for dismantling purposes, is virtually continuous. What used, in the old days, to be called the nacelle is a particularly capacious box structure in which the pilot and the passenger are seated in tandem beneath a trans­parent “lid” giving more than ample headroom. The three-piece windscreen must be nearly two feet in depth and, since the machine is of the pusher type, the view in all the essential directions should be as good as is possibly obtainable.
   The two fully cantilever booms which support the tail unit are built up of four members in diamond section with plywood stiffening. The tailplane and the two fins are each again of ply-stressed construction and the control rods for the elevator and rudders pass through the centre of the port and star­board booms respectively. There is, in fact, no exterior control mechanism and the entire machine is as clean as the attention to personal comfort in the nacelle will permit.
   The three-piece trailing-edge flap extends from aileron to aileron and each section is a double-surfaced structure.
   The engine fitted to the prototype is an A.D.9 R. British Salmson radial with a maximum output of 68 b.h.p., in which a four-bladed airscrew is driven through a reduction gear. The slow airscrew speed should permit good efficiency at the lower end ot the speed range. The fuel tanks are arranged in the centre section on the starboard side, and there is a gravity tank for direct feed to which fuel is pumped by means of a handle in the cockpit. This tank has a capacity sufficient for three-quarters of an hour’s flying, and beside the pilot there is an overflow indicator to tell him when he has duly filled it up. In all, the fuel capacity is such that the estimated endurance at cruising speed is as much as five hours.
   Since it is obviously possible to break any undercarriage by either gliding it or allowing it to sink into the ground at a high vertical velocity, Mr. Arpin has not attempted to give the tricycle undercarriage anything very exceptional in the way of travel. He feels that a machine should normally be landed in a more or less orthodox fashion and the tricycle arrangement is designed in this case merely to give the pilot, so to speak, a second chance and to improve the ground characteristics generally. The Arpin’s undercarriage is, in effect, a rationalised tricycle. The castering front wheel is steerable.
   A brief test flight was carried out last week-end by Mr. Wynne Eyton, but no actual performance figures are yet available. The estimated maximum speed of the Arpin is 108 m.p.h., the cruising speed (at 65 per cent, power) is expected to be 95 m.p.h. and the landing speed, with the flaps down, rather less than 40 m.p.h.

Flight, October 1938

British Sport and Training types

ARPIN

   AS the first machine in this country to be designed around the tricycle undercarriage the Arpin Pusher is of particular interest. More recently the prototype has been in use as a test bed for Mr. Maclaren’s "crabbing" undercarriage, the principles of which were recently described.
   The company’s next move will be to install a Cirrus Minor engine in place of the original Salmson which was used for the preliminary work, and a new nacelle is being designed around this unit.
   The construction of the Arpin is of wood with a stressed-ply wing, and the tail is carried on two cantilever booms with twin rudders. In design­ing the machine Mr. Arpin has paid special attention to the provision of an outstandingly good field of view for the pilot, who sits in the forward of the two tandem seats, and to the layout of a three-wheel undercarriage which will be capable of taking any possible taxi-ing and landing loads. The upward movement of the legs is more than ample, but the main features of the undercarriage are in the width of the track and the length ol the wheelbase. The former gives good cross-wind stability and the latter prevents the pitching motion which is apparent in the majority of short-wheelbase tricycle types.
   Arpin data with Cirrus engine: - Span, 31ft. 6in.; length, 23ft. 5in.; all-up weight, 1,350 lb.; maximum speed, 115 m.p.h.; cruising speed, 101 m.p.h.; and rate of climb, 800 ft./min.
Makers:- M. B. Arpin and Co., Longford. West Drayton, Middlesex. (Coinbrook 189.)

Flight, September 1939

To-day's Light Aeroplanes

ARPIN

   ONE of the first of the "rational" aeroplanes, the Arpin, is a tandem-seater cantilever low-wing pusher monoplane. In experimental form this tricycle type was fitted with a Salmson engine; the present Mark II version has a Cirrus Minor engine, of 90 h.p., driving a four-bladed pusher propeller. The Arpin is normally flown from the front seat, and is of all wood construction, with a ply-covered wing and boom supported tail unit.

Span 31ft. 6in.
Length 23ft. 5in.
All-up weight 1,500lb.
Max. speed 112 m.p.h.
Cruising speed (2,300 r.p.m.) 101 m.p.h.
Landing speed (flaps down) 44 m.p.h.
Initial rate of climb 680 ft./min.
Makers: Arpin Manufacturing Co., Ltd., 8 and 9. Long Acre, London, W.C.2.