The Blackburn Firebrand was a single-engine fighter aircraft designed to Air Ministry Specification N.11/40 by Blackburn Aircraft. It was designed around the Napier Sabre III 24-cylinder H-type engine as a single-seat fleet fighter for the Royal Navy.
Work on the B-37 Firebrand proceeded slowly. An unarmed prototype first flew on 27 February 1942, the armed Firebrand F Mk. I second prototype flying on 15 July of that year. The Sabre engine was also used in the Hawker Typhoon, a fighter already nearing production, and was earmarked for that aircraft. A new engine was needed, along with airframe improvements to handle it; along with these modifications it was deemed appropriate to convert the Firebrand into a strike fighter capable of carrying torpedoes, bombs, and rockets as well as engaging in air to air combat. Only nine production F Mk. I aircraft were built. The Firebrand was unusual in that there was an airspeed gauge mounted outside of the cockpit so that during landing the pilot would not have to look down into the cockpit to take instrument readings, presaging the development of the modern heads up display.
By the time service trials were ongoing the Fleet Air Arm was operating the Supermarine Seafire as a carrier-borne fighter and a new role as a torpedo-bomber was envisaged for the Firebrand. The first strike variant, the Firebrand TF Mk. II (B-45), flew on 31 March 1943, and was an adaptation of the Mk. I. It incorporated slightly wider wingspan that allowed carriage of a torpedo between the retracted main landing gear. Like the Mk I, the TF Mk. II only saw a very limited production of 12, and was followed by the Firebrand TF Mk. III with the Bristol Centaurus VII radial engine. After the first flight on 21 December 1943, problems arose: the new engine produced more torque than the Sabre, and rudder control was insufficient on takeoff. The TF Mk. III was determined to be unsuitable for carrier operations, and work began on an improved airframe that would be better-suited for the Centaurus. The aircraft had killed two test pilots and, although after six months' modification Dennis Cambell did manage the first successful deck landing, the type was generally regarded as one of the war's worst aircraft
The Firebrand TF Mk. IV (B-46), as the new development was designated, featured a newer Centaurus IX engine and larger tail surfaces for better low-speed control. The enlarged rudder was horn balanced, and the wings now featured dive brakes on both upper and lower surfaces. The TF Mk. IV first flew on 17 May 1945, and was the first version of the Firebrand to enter mass production, with 102 built. The later Firebrand TF.5 featured minor aerodynamic improvements and was also built in large numbers, with 68 entering service. A further 40 TF Mk. IVs were converted to the TF.5 standard.
The final production version was the Firebrand TF Mk. 5A.
A proposal to fit floats was designated as the Blackburn B-43 by the company, to be used for fighter defence for areas without room for an airfield, the idea was dropped.