Devised and made by Mr Sandy Hudson Jr, a law enforcement operator of Black Mountain, North Carolina, the Tri-Motor is a powered conversion of a Schweizer SGU 1-19 single-seat sailplane fitted with three West Bend go-kart engines producing a total of 17.3hp and each driving a 2ft 1 in diameter two-blade wooden pusher propeller. Two West Bend Model 70013 engines are mounted on pylons on each side of the fuselage aft of the cockpit and between the wing bracing struts, and a West Bend Model 70012 is carried on a pylon on top of the rear fuselage in front of the fin. The total fuel capacity is approximately 2 US gallons, a small separate tank for the rear engine being mounted on the fin leading edge.
This powered conversion of SGU 1-19 N91817 was started in May 1962 and completed in September 1963 at a cost of $1,000; Mr Hudson won an award for the lowest powered aircraft with the Tri-Motor at the 1963 Fly-In of the Experimental Aircraft Assocation.
The standard SGU 1-19 is a utility and training single-seater of early postwar design with an all wood constant chord fabric-covered wooden wing with two spruce spars, spruce and mahogany plywood ribs and a ply leading edge. The fuselage is a fabric-covered welded chrome-molybdenum steel tube structure, and the landing gear is an unsprung monowheel with a single skid mounted on rubber blocks ahead of it, and a rubber-mounted tailskid. The tailplane and elevators are fabric-covered welded steel tube surfaces, the tailplane being braced, and the fin and rudder are either of fabric covered wooden construction when the SGU 1-19 is supplied in kit form for amateur builders, or of fabric covered steel and aluminium alloy when factory built. The pilot could sit in an open cockpit, or a transparent canopy could be provided as an optional 'extra'.
Span: 36 ft 5 in
Length: 21 ft 0 in
Height: 5 ft 6 in
Empty weight: 449 lb
Max weight: 670 lb
Max level speed: 55 mph at sea level (power on)
Cruising speed: 45 mph (power on)
Rate of climb: 150 ft/min at sea level
Take-off run: 750 ft (power on)
Endurance: 8 min