During his career, Summers flew many first flights on prototype aircraft, (a record of 54 by a test pilot), from the Supermarine Spitfire, to the Vickers Valiant.

[1] Summers received his nickname "Mutt" during his early days in the RAF from his habit of urinating before takeoff on the small rear wheel or skid of the aircraft he was testing.

[citation needed] Paul Brickhill (in The Dam Busters) referred to the two test pilots Joseph Summers and Jeffrey Quill, as "Mutt" and "Jeff", alluding to the characters in the American comic strip created by Harry Conway "Bud" Fisher.

After six months he was transferred to the single-seater flight at Martlesham Heath, where he helped to test, among other types, the Gloster Gamecock, Bristol Bulldog, Hawker Hornbill and Avro Avenger.

On 5 March 1936 Jeffrey Quill flew Summers in Vickers' Miles Falcon from Martlesham to Eastleigh Aerodrome, where he was to fly the new F.37/34 fighter which had the military serial number K5054.

A new and better-shaped wooden propeller meant the Spitfire reached 348 miles per hour (560 km/h) in level flight in mid-May, then Summers flew K5054 to RAF Martlesham Heath and handed the aircraft over to Squadron Leader Anderson of the Aeroplane & Armament Experimental Establishment (A&AEE).

During this period of the war, all leading test pilots of the main aircraft manufacturers were ordered by RAF Command to support Groups No.

Early in the Battle of Britain during an attack over south east England, pilot James Harry "Ginger" Lacey of 501 Squadron from RAF Middle Wallop, complained he had a problem with his Hurricane's engine, and felt it was too dangerous to accelerate any faster than he was.

In preparation for the Dambusters Raid in May 1943, Summers was test pilot for the experimental bouncing bomb dropped from a Vickers Wellington near Portland, Dorset, a job given to him by close friend Barnes Wallis.

The prototype of the turboprop civil transport Vickers Viscount was flown from Wisley Airfield by Summers and Jock Bryce for 10 minutes on 16 July 1948.

During a test flight on the first dual Gloster Grebe, the aircraft spun flat to within 150 feet (46 m) of the ground, coming out completely stalled with full engine.

In a full-power dive in the Hawker Hawfinch, a fuselage bay collapsed at about terminal-velocity speed; the anchorage for the Sutton harness was in the tail and this pulled him back and nearly broke his neck.

He had released his harness and was on the centre section when the machine stopped rotating and went into a dive, enabling him to regain control by pushing the stick with his foot.

His most dramatic escape was in 1945, when structural failure in a Vickers Warwick caused full rudder to be involuntarily applied at 3,000 feet (910 m) over Weybridge, Surrey.