SAF THREE-ENGINED MONOPLAN
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The Westland Wessex, Used Successfully on British Air Services„ is Now Available in Improved Form, Seating Seven Passengers
THE recent modification of the Westland Wessex, to make it seat seven persons in addition to the pilot (instead of five) without loss of fuel-tank range, revives the interest in this well-tried aeroplane. The alterations increase the unladen weight by 100 lb. and permit 200 lb. more payload to he carried, so raising the all-up weight from 6,-000 lb. to 6,300 lb.
The cabin has four separate and comfortable armchairs, and there is a fold ing seat for two at the rear. The seventh passenger may be seated beside the pilot in the comfortable cockpit, reached from the cabin, provided, of course, that no navigator or wireless operator needs, to be carried.
Controlling Factors in Design.
The paramount factors considered in the design have been safety, easy maintenance and comfort, and the machiue was first produced for Imperial. Airways, Ltd., the policy of which concern has always been based on safety rather than a high cruising speed. The strut-braced wing, although, possibly, not so clean-looking as the full cantilever type, gives a high strength-weight ratio. .
To take the extra 800 lb., the axles have been .strengthened, and high-pressure tyres give place to medium-pres-, sure tyres. The track is increased from 15 ft. to 16 ft. 10 ins. Behind the cabin are a lavatory and a commodious luggage compartment ; below the pilot's floorboards is a small luggage boot.
For short services, such as ferries, on which lavatory accommodation is unnecessary, even the 6,000-1b. -model can
DX0 be arranged to seat six in the cabin in return for some sacrifice of petrol load. On the other hand, for long-distance work bigger (but not heavier) tanks can be supplied in the eight-seater. which will give six hours' range with a correspondingly lower pay-load.
Imperial Airways, Ltd., has had three. of these machines, two of which were ordered as recently as last spring, when, of course, there were several craft of this size to choose from. The Belgian S.A.B.E.N.A. concern has run four Wessex 1930 models for over three years. One was used on the G.W.R. Birmingham-Plymouth line last summer and another has done remarkable service an the Isle of Wight ferry.
Safety a Cardinal Feature.
The, outstanding feature of the machine is its safety, for with any engine out of action the machine not only will keep flying, but will maintain a good practical height of 4,500 ft., sufficient to allow of climbing over ground mists. This is a most important point, because . mists are so prevalent in this country and we have so many hills of altitude
approaching 1,900 ft. To facilitate *ring the machinewith an outboard. engine dead-, the Wessex has a rudder-bias gear, which preserves the pressure balance on the rudder bar.
This feature was well demonstrated to us in a recent test flight,
The Commercial Motor has always stressed the safety factor of multiple engines, and it is one of the principal reasons for the appearance of this
article on the Wessex. In any condition of flying one experiences a justifiable senSe of security when in such a machine, and, in the most improbable event of two engines failing, the third engine would serve to reduce the rate at which the machine would lose height. In emergency it could be run "all out" to delay the landing a little longer.
With two engines running, of course, the pilot may seek a landing ground at his convenience, and, as the petrol feed to every engine is by gravity from a small collector box supplied (also by gravity) from the two wing tanks, the entire supply is available for any engine.
The Genet Major is a particularly reliable unit, and, in this airframe, pro duces an excellent aircraft from the point of view of regularity of operation. Travelling in the seat beside the pilot, we were struck by the excellent view in all directions except, perhaps, upward and backward.
The noise in the cabin is moderate, the range of vision for passengers is excellent, and it is convenient to be able to step in and out without climbing over wings. There is ample foot room ; armrests and elbow niches are provided. Ventilation and heating are under passengers' control. There is easy access to the cockpit, and there is an emergency exit in the roof, which could be used in the event of a forced descent on water. The headroom in the cabin is ample.
Operating-cost Considerations.
Concerning cost of operation, -it may be noted that most operators make a practice of cruising their Wessex machines (without Townend rings) at 95
An interior view of the cabin looking forward into the pilot's compartment, the communicating door being open. The comfort and loftiness of the cabin are emphasized, also the large area of the windows and the ease of access
to the cockpit.
m.p.h. (2,100 engine r.p.m.), and at this economical speed obtain a fuel consumption of 191 gallons per hour. From the point of view of maintenance, with the tail raised, all engines are accessible from the ground and all controls are by tubular rods with Tecalemit greasers where required.
The fuselage comprises a forward portion of composite construction, a cabin section of wood construction, and a rear part of metal. The wing structure is in two sections and is of wood, with swaged-rod internal bracing ; built-up box spars of three-ply and spruce are used. The wing is fabric-covered except for the three-ply nose of the leading edge. Control on the ground is facilitated by the multiple engines and the Bendix wheel-brakes. Every machine is bonded for wireless and there is space for a wireless set and operator beside the pilot.
The maker of the Wessex is the Westland Aircraft 'Works, a branch of Petters, Ltd. (the oil-engine manufacturers), Yeovil, Somerset.