When rolled out, the Gregor FDB-1, as it was called, for Fighter Dive Bomber, was not only robust and solid, it also looked exceptionally sleek. Registered CF-BMB, the letters embossed in white over a high gloss metallic dark gray paint job, the dual purpose aircraft's only other markings were ten horizontal white bands on its rudder.
Early in 1938, in a spirit of Commonwealth cooperation, a wooden model of Gregor's new Model 10 fighter was sent to Hawker Aircraft's wind tunnel facility at Kingston upon Thames, England. Manufacture of the prototype began at Thunder Bay, on the north shore of Lake Superior, shortly thereafter. The aircraft, c/n 201, was completed by mid-December 1938, "amid an atmosphere of war jitters, well salted with tales of German spies visiting the factory in disguise."
On its first flight test on 17 December 1938 Can-Car Test pilot George Adye put the FDB-1 through a preliminary flight test program carried out at Can-Car's Bishopfield Airport, Thunder Bay, on Lake Superior. Ayde immediately noted the upper gull wing was a major defect as on takeoff and landing, a pilot's vision was severely limited downward and forward. Ted Smith who tested the FDB-1 in 1941 was more succinct when describing visibility over the gull wing, "blind as hell." While expressing enthusiasm over its maneuverability, Ayde warned that the controls were far too sensitive and the angles of the lowered flaps too great. His assessment was correct; on a subsequent landing, the prototype flipped on its back, although the damage was kept to a minimum due to its rugged construction.
Among the new devices incorporated within the FDB-1 was an anti-spin parachute in its tail cone. The pilot activated the parachute from the cockpit by a three-position switch. The first opened the cone, the second deployed the chute behind the aircraft, and the third released the connecting cable.
Recorded top speed was only 261 mph (420 km/h) at 13,100 ft (3,990 m), with the old P&W R-1535-72 engine of 700 hp, which had powered the Grumman F2F-1. But that aircraft, with a slightly lower empty weight, had only reached a top speed of 230 mph (370 km/h). With the installation of an improved P&W R-1535-SB4-G of 750 hp, top speed was expected to rise to 300 mph (500 km/h). Meanwhile, Gregor had already programmed his fighter to accept the 1200 hp. P&W R-1830 Twin Wasp then being installed in Grumman's new monoplane fighter, the XF4F-3; and with it, he fully anticipated a top speed of 365 mph (587 km/h). Initial rate of climb was an exceptional 3,500 ft (1,070 m). per min, compared to Grumman F2F's 2,050 ft (625 m) per min. with same engine. Service ceiling was estimated at 32,000 ft (9,800 m), 5,000 ft (1,520 m) higher than the F2F's. FDB-1 had a cruise of 205 mph (330 km/h), a low-speed capability of 72 mph (116 km/h) clean and, with flaps and slats open, 58 mph (93 km/h). All these figures were reached without armament, ammunition, armor plate and other military equipment including self-sealing fuel tanks.
Designed, built and tested in less than eight months, the FDB-1 Model 10 was sent to Saint-Hubert Air Base, near Montreal, for preliminary service testing with the Royal Canadian Air Force. After extensive trials, pilot evaluations complained of severe canopy vibration at speed and during strenuous aerobatics, and it was recommended that all testing be restricted until this bothersome defect had been remedied. Unfortunately for Gregor and Can-Car, further tests undertaken by the RCAF showed that his first projections were extremely optimistic and doubted further refinements would make a difference. Nevertheless, the FDB-1 did demonstrate amazing maneuverability; below 15,000 ft (4,600 m), in spite of an adversary's superior speed, no contemporary single-seat, low-wing monoplane could successfully engage Gregor's design which climbed like a "homesick angel," with an initial rate of 3,500 ft (1,070 m) per min, one third better than the new Hurricane and Spitfire. Test pilot Ted Smith thought that the FDB-1 was intended for "mountain" fighting once he sampled its phenomenal climbing ability.