Flight, April 1935
The "All-wing" Aeroplane: Some Interesting Foreign Departures from Conventional Design
AFTER many years of worship of the aspect ratio goddess, there is a noticeable tendency in several countries to depart from this ideal
and go almost to the other extreme of using a wing which is flying "end on," or, more correctly, "corner on." Two excellent examples have just appeared, one in America and the other in Italy.
Although it is unslotted, and flapless into the bargain, the American Hoffman two-seater monoplane, which employs a wing of exceptionally low aspect ratio, is claimed to possess a speed range of 30 to 135 m.p.h. - and that on the power of an 85 h.p. engine and when using a fixed undercarriage!
The span is only 22ft. 8in. and the maximum chord as much as 14ft. 6in., giving an area of 237 sq. ft.
Welded-steel tubing is employed for the centre section, fin and rudder, the remainder of the machine being of spruce. Three spars are used for the wing, with double-drag trussing in each bay. The centre spar is twenty inches deep and the wing sections are of the M6 type, with M1 at the tip and extended M6 at the centre.
There are two elevators, with push-and-pull connections, and the "tip" ailerons are operated with a torque tube. Two stabilisers are mounted outboard of the elevators, which, it would appear, are adjustable over a range of incidence. A retractable undercarriage has been specified for the machine, although the tests were conducted with a rigid gear of the type shown in the drawings.
An English 85 h.p. "Cirrus" engine is fitted, and drives an airscrew 7ft. in diameter. Positive petrol feed, when the machine is in any position, is ensured by a Ford pump.
During tests the landing speed proved to be 28 m.p.h. The landing approach at stall angle is steep, and just prior to the wheels touching the ground the machine goes into a flattened glide. This behaviour is attributed by the designer to the positive rake of the trailing edges and the diverging air flow. With a higher wing loading the characteristic may not be achieved. Vision, it is admitted, is not so good as in conventional aircraft.
The designer visualises, as a future development, a pusher, or twin engined, version, with a three- or four-wheel undercarriage. This type, he believes, with a low wing loading, may be the solution to the "Air Flivver" problem. One feels that the view would have to be considerably improved, however, if the machine were eventually to become the "motor car of the air."