The De Havilland Goblin turbojet

The De Havilland Goblin was originally called the Halford H-1, after its designer, Frank Halford. The second British jet engine to fly, it was based on the Centrifugal Compressor technology pionered in Britain by Sir Frank Whittle. It first ran on 13th April 1942, and achieved its first flight fitted to a Gloster Meteor on the 5th March 1943

The basic design of the engine was similar to the Whittle W-1, with a Centrifugal Compressor at the front feeding 16 "flame cans" the exhaust from which powered a single stage axial turbine. Unlike the Whittle engine which used flame cans that were folded back, the Frank Halford designed De Havilland Goblin Engine used a "straight through" flame can, which allowed for a simpler, cleaner design, at the expense of a slight increase in length.

Halford had started his London design consultancy in 1923, where he had designed the famous De Havilland "Gipsy" air-cooled inline engines. Later he had worked on the design Napier Sabre aero-engine, a powerful piston engine capable of up to 3,500 hp, so it was natural that he would join the early British jet engine development

De Havilland wanted to use the Halford design in their "Vampire" jet, and purchased Halfords company in early 1944. At this point the Halford H-1 became the De Havilland "Goblin"

The initial version of the Goblin engine for use in the De Havilland Vampire gave only 2100lbs of thrust, but this compared well with the Whittle engine. As development continued, later engines increased in power culminating in the De Havilland Goblin 4, with 3750lbs thrust.

While it had been designed with the De Havilland Vampire in mind, the Goblin engine went on th be used by other aircraft, with a total of 4,400 units being produced.

Engine Operation

• Air enters the engine at the front, fed from air intakes at the root of each wing.
• The centrifugal impeller draws the air in and compresses it. It is then fed to the 16 "flame cans" arranged around the engine. Some of the air (the "secondary air") is routed around the "flame cans" and is drawn into the flame cans through perforations to cool the hot gases before they reach the turbine blades.
• Fuel is pumped to the burner, where it ignites, producing a rapid gaseous expansion.
• Stationary stator blades guide the gases onto the turbine blades.
• The passage of the gases through the turbine blades causes the turbine to rotate. As the impeller is linked to the turbine by a common shaft, this also rotates, drawing more air into the engine, maintaining a continuous process.
• The gases exit the tailpipe at speed, producing thrust.

Robert Kent