Flight, October 11, 1917.
THE LAWSON TRAINING TRACTOR BIPLANE.
WE have just received from the Lawson Aircraft Corporation, of Green Bay, Wis., U.S.A., the accompanying illustrations and particulars of a decidedly businesslike-looking tractor biplane recently completed at their works. This machine is of the primary training type, built to conform with the specifications No. 1,000 issued by the U.S. Army.
Besides several important constructional features - details of which we are not for the present at liberty to disclose - the Lawson iractor possesses the following features valuable to machines of this type: Its minimum flying speed is as low as 37 m.p.h., whilst the maximum speed is 75 m.p.h. The landing chassis is extremely strong and the axle carrying the two main wheels is well sprung, allowing the axle a wide range of action vertically between the guide plates, which may be seen in the view of the uncovered fuselage. A third, additional, wheel mounted in front of the other two, provides against the machine turning over on its nose should the pupil land the machine at too sharp an angle.
As may be seen, the fuselage, which is a little over 25 ft. in length, is of rectangular section, with spruce longerons and struts, and wire bracing. It is covered with Irish linen as far as the engine housing, which latter part is covered with sheet metal. The tandem seats are mounted on stout longitudinals carried by second, third and fourth sets of upright struts. Dual stick control is installed.
The engine is a 100 h.p. Hall-Scott model A-7A, coupled direct to an 8-ft. diameter tractor screw having an 8-in. pitch. The engine mounting consists of two stout bearers, supported by a system of tubular stays, as shown. The radiator is mounted above the engine underneath the leading edge of the top plane. The exhaust pipe extends upwards and rearwards over the top plane.
On its first flight, under the pilotage of Mr. Alfred Lawson, the machine left the ground after a run of 40 ft., and when landing stopped within 70 ft. of first point of contact.
The main characteristics of the Lawson tractor are as follows :-
Span, (top) 44 ft. 6 ins., (bottom) 32 ft. 6 ins.; chord, (top) 7 ft., (bottom) 6 ft. 5 ins.; gap, 6 ft. 9 ins. ; stagger, 9°; dihedral angle, 1°; wing section, U.S.A.3; angle of incidence, 4 1/2 °; overall length, 25 ft. 6 ins.; height, 10 ft.; weight, empty, 1,300 lbs.; useful load, 600 lbs.; loading, 4.5 lbs. per square foot; speed range, 37-75 m.p.h.; climb, 2,600 ft. in 10 minutes; gliding angle, 1 in 10.