The test aircraft appears to be a prototype P-40 Warhawk, the predominant U.S. fighter plane at the outbreak of World War II. It is also very similar to a Bf-109 and a Spitfire. So, other than the cockpit being further to the rear, a smaller engine, the wings requiring bracing, the vertical stabilizer being smaller, the horizontal stabilizer attached lower, the fuselage aft of cockpit being less tapered, the test plane is nearly identical to a P-40.