The Gregor FDB-1 was a Canadian biplane fighter, designed in 1938 by Michael Gregor and manufactured by Canadian Car and Foundry. Despite having some advanced design features such as flush rivetted all-metal construction and a retractable undercarriage, the final generation of biplane fighters was being supplanted by monoplanes and the Gregor FDB-1 was obsolete before it flew. Despite the Royal Canadian Air Force's desperation for modern fighters, the sole example remained unsold and was eventually lost in a fire in 1945. The Gregor FDB-1's model designation stood for Fighter Dive Bomber indicating its intended roles. In 1938, Georgian-American expatriate designer Mikheil Grigorashvili (anglicized as Michael Gregor) joined with Canadian Car and Foundry, which at that time was Canada's leading manufacturer of railroad rolling stock. He was hired to design a fighter. They wanted to enter the aircraft market, but had no experience in that industry. Instead of creating their own designs, Can-Car was producing aircraft under license that had been designed elsewhere. In 1936, Grumman and Canadian Car & Foundry or "Can-Car" concluded an agreement for production of 50 Grumman SF-1 biplane carrier fighters known as GE-23s or Grumman Export 23s, to be built in Canada. There were still some who doubted the merits of the monoplane over the biplane in 1938, and Michael Gregor was one of them. All the major powers still operated biplanes in front line fighter units, however they were being replaced with monoplanes in every case. The hydraulically operated landing gear retracted into wells on the sides of the fuselage ahead of the lower wing. The fuselage of the Model 10 FDB-I was a monocoque shell of circular cross section with a flush-riveted aluminum stressed-skin. 95 US gallons (360 litres; 79 imperial gallons) of fuel was carried in a pair of semicircular tanks mounted side-by-side between the wheel wells. The structure was stressed 60 percent above requirements. A pair of fuselage-mounted .50 cal. machine guns, synchronized to fire through the Hamilton Standard propeller's disk, were part of the design, but the armament was never installed. Additionally, two 116 lb (53 kg) bombs could be carried, one under each lower wing. The cockpit was enclosed with a rearward sliding canopy and the engine was faired in with a NACA cowling reminiscent of the Seversky monoplane fighters that Gregor had worked on. Among the new devices incorporated in the FDB-1 was an anti-spin parachute in the tailcone. The pilot activated it from the cockpit with a switch that opened the cone, deployed the chute and released the connecting cable. The metal wing structure was fabric covered behind the front spar as were the metal-framed control surfaces. The top wing featured full span slats, plus all-metal split flaps between the wing roots and ailerons. The bottom wing also incorporated split flaps. The center section of the top wing curved down to meet the fuselage, in a gull-wing configuration like earlier Polish and Soviet fighters such as the Polikarpov I-153. The wings were braced with "V" interplane struts. Instead of flying and landing wires, a single strut ran between the root of the top wing and the foot of the V strut on the lower wing on each side. Torque tubes moved the control surfaces, except for the rudder, which was partially operated by cables.
