Ackroyd started his engineering career with an apprenticeship at Saunders-Roe in East Cowes on the Isle of Wight. His final job as an apprentice was in the design department working on the SR53 prototype fighter aircraft with a mixed jet and rocket propulsion system.
Ackroyd then took a lead role in designing and engineering at Cushioncraft for Britten-Norman.[2] The CC7 launched in 1969 but when the company was sold Ackroyd was again out of a job.
After two years in Germany with the aircraft manufacturer Dornier, he became the project designer of the world's first production electric car for the Isle of Wight-based Enfield Automotive, which commenced sales in 1973 as the Enfield 8000.
In 1978 he joined the Thrust 2 land speed record project, which went on the achieve the record in 1983.[3]
In 1981 he was involved with the Vanishing Point rocket sled which achieved the World Ice Speed Record at 248 mph (399.1 km/h) in 1981, and in 1999, the Gillette Mach 3 Challenger which set the motorcycle speed record of 365 mph (587.4 km/h).
In 1987 he teamed up with the Swedish aeronautical engineer Per Lindstrand and Richard Branson for a project to cross the Atlantic in a balloon. Ackroyd designed the pressurised capsule for the Virgin Atlantic Flyer, and the first to cross the Atlantic Ocean in 1987.