THE AIRSPEED ” FERRY “
AMONG the numerous types of aircraft which are being used in connection with Sir Alan Cobham’s tour, one newcomer is of particular interest.
This is the “Ferry,” the first machine to be turned out by the recently formed company of Airspeed Ltd., York.
The designer is Mr. A. Hessell Tiltman, B.Sc., A.F.R.Ae.S., who some years ago was associated with the De Havilland Company and was also concerned with the construction of the airship R.100.
The” Ferry” is a cabin machine of low horse power, and it has been built primarily for use on ” feeder” lines and for charter work. Its cabin will accommodate ten passengers at an average weight of 165 lbs. each, but for ordinary air service the disposable load of 2,100 lb. would probably be divided up into seven passengers with a small amount of luggage and fuel for five hours’ flying. The ” Ferry ” has three engines, two mounted outboard on the bottom wings and the third in the centre section. The wing engines are D.H. ” Gipsy ” II and the centre engine is a ” Gipsy ” III. Behind and. slightly above the latter is fixed the fuel tank which feeds all three power units by gravity. In a later type, this tank will be lowered into an extension of the centre engine’s cowling. The aircraft is constructed mainly of wood with wings of orthodox type with spruce box spars, and the fuselage is flat sided with spruce framework covered with birch three-ply. An unusual feature is the anhedral angle of the lower wing roots ; the design of the machine necessitates this arrangement, and in incorporating it, two added advantages have been introduced since it gives a very good view from the side windows of the cabin, and also blanks off the port and starboard engines so that exhaust and airscrew noise is appreciably reduced. Absence of noise
in the passengers’ compartment is, in fact, a noticeable feature in the “Ferry,” and this is probably due to the fact that in addition to the blanking off of the wing engines by the wing roots, the middle engine is mounted in the centre section and not in the nose.
The cabin measures 12 feet 7 inches long, is 5 feet 9 inches h.gh and is 3 feet 9 inches wide. The pilot’s cockpit is arranged in the nose and it is enclosed. The two doors by which the passengers enter the machine are set low, and with the tail down, they are only about 12 inches from the ground, thus obviating the necessity of steps. The pilot enters the cockpit through a door in the front bulkhead of the cabin. The undercarriage is of the split-axle type, and in the shock-absorber legs are springs which may be compressed 4 inches, and there is an oil damping device which allows of a further travel of 6 inches. The landing wheels are fitted with Palmer hydraulic brakes. These are applied by a lever in the pilot’s cockpit, and small plungers actuated by the rudder-bar give
increased braking on whichever wheel it is desired to turn.
The ” Ferry ” has a top speed of 108 m.p.h., and she stalls at 49 m.p.h. Fully laden with ten passengers up, and fuel for two hours flying, she unsticks in 100 yards in still air, and the initial rate of climb is 520 feet per minute. At a loaded weight of 5,000 lbs., the machine will not only maintain height at 5,000 feet with two engines running only, but will, in fact, climb at the rate of 50 feet per minute. The following are the main dimensions of the aircraft :
Span 55 feet, length 39 feet 8 inches, height 14 feet 3 inches, weight (empty) 3,450 lbs., (gross) 5,600 lbs., service ceiling 15,500 feet.
The ” Ferry ” is interesting in showing the growing tendency of manufacturers to adopt the multi-engine principle for machines of comparatively small size and power, and it is quite possible that before long such a practice will be used in the construction of so-called light aircraft.