According Larry Matanski's daughter, Neesja Christoffersen-Pedersen, it was Larry's long-time friend, Emerson Wallace on the controls when the photo above was taken.
The six-seat cabin was unpressurized; the nose wheel landing gear was retractable with the main wheels stored into the sponsons. The sponsons were attached to stubs and from these stubs two struts supported the wing where they connected at the twin-booms.
The production model would have a 24 in (0.56 m) fuselage stretch, additional cabin windows, optional pressurization, 62 sq.ft (5.76 sq.m) increase of wing area, sponsons moved 5 in (0.13 m) out, a 4 in (0.10 m) wider rear hull, fuel tanks in the stubs, and larger fins and rudder.
From land the Avalon needed 800 ft (244 m) to get airborne, from water this was 1,200 ft (366 m). Landing run on land was 650 ft (198 m), on water this was 700 ft (213 m). Maximum landing weight was 5,100 lb (2,313 kg), cruise speed was 200 mph (322 kmh), stall speed 65 mph (105 kmh).
A seven-seat twin-engined Avalon Twin Star 800 was developed to be powered by two Allison 250-C20Bs providing a total of 820 shp driving a single pusher propeller. Also designed were the seven-seat Airmaster Avalon Twin Star 1000, featuring two wing-mounted engines providing a total of 1,000 shp, and the military Airmaster A-1200 Guardian, powered by two engines providing a total of 1,200shp, but except for the Avalon 680 prototype no further aircraft have flown.
Span: 44 ft 0 in (13.41 m)
Length: 32 ft 0 in (9.75 m)
Height: 12 ft 6 in (3.81 m)
Wing area: 264 sq.ft (24.53 sq.m)
Empty weight: 3,300 lb (2,404 kg)
Max T/O weight: 5,300 lb (1,497 kg)
Max speed: 230 mph (370 km/h) at 16,000 ft (4,877 m)
Max climb: 2,200 ft (671 m)/min
Range: 900 mls (1,448 km)