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General Electric T58 / CT58

Bristol Siddeley Gnome
Rolls-Royce Gnome



The General Electric T58 is an American turboshaft engine developed for helicopter use. First run in 1955, it remained in production until 1984, by which time some 6,300 units had been built. On July 1, 1959, it became the first turbine engine to gain FAA certification for civil helicopter use.

Development commenced with a 1953 US Navy requirement for a helicopter turboshaft to weigh under 400 lb (180 kg) while delivering 800 hp (600 kW). The engine General Electric eventually built weighed only 250 lb (110 kg) and delivered 1,050 hp (780 kW) and was soon ordered into production. First flight was on a modified Sikorsky HSS-1 in 1957, and civil certification for the CT58-100 variant was obtained two years later.

The main production version of the engine was the T58-GE-10, developing 1,400 hp (1,044 kW). The most powerful version, the T58-GE-16, produces 1,870 hp (1,390 kW).


General Electric T58


 The Rolls-Royce Gnome is a single spool turboshaft engine originally developed by the de Havilland Engine Company as a licence-built General Electric T58—a mid-1950s design. The Gnome came to Rolls-Royce after their takeover of Bristol Siddeley in 1966, Bristol having absorbed de Havilland Engines Limited in 1961.

A licence to manufacture the T58 was purchased in 1958. The T58 had begun bench testing in 1955 and by 1958 had already been used in helicopters and de Havilland were able to test their first engines in a Westland Whirlwind and Wasp helicopters in August 1959.

A free-turbine turboshaft, it was used in helicopters such as the Westland Sea King and Westland Whirlwind. The design was sub-licensed to Alfa-Romeo and the IHI Corporation.

There were two series produced: the "H" turboshaft for helicopter use, and the "P" turboprop for fixed-wing aircraft.

A single-stage turbine drives the 10 stage all-axial compressor, whilst a two-stage free power turbine drives the load. The combustor is annular. The Gnome differed from the T-58 in having a British developed fuel control system (Lucas).

Because an all-axial design is employed, the final stage compressor rotor blades are amongst the smallest ever manufactured. Normally, a small engine such as this would feature an axial/centrifugal or even a double centrifugal compressor.

The engine was one of the first developed with an analogue computer, de Havilland's own, as part of the fuel control system, specifically to control fuel flow during acceleration to prevent engine surge from occurring.


The General Electric T58 remained in production until 1984, by which time some 6,300 units had been built. On July 1, 1959, it became the first turbine engine to gain FAA certification for civil helicopter use.
T58s, have been converted to turbojet by the removal of the power turbines and were used as jet engines on:
Maverick TwinJet 1200
Sipa 200
Gross Panther Replica
T58 converted to turbojet by Les Shockley (2003). Named SHOCKWAVE 800+
The engine weighs just 300 pounds and is capable of producing up to 840 pounds of thrust.


The Carroll Shelby turbine cars entered in the 1968 Indianapolis 500 race were powered by T58s. The cars were found to be using variable inlets to get around the USAC regulations on the maximum allowable inlet size and were disqualified.

Turboshaft engines like the GE T58, Lycoming T53/T55 are also used to power high performance powerboats, such as aport and offshore vee, and catamaran hulls like the Skater "Jet Set" or Mystic Powerboats "My Way", water jet river racers like Unatural Dissaster and hydroplanes. Some of these boats run in excess of 200 mph, despite them being open cockpit pleasure boats.




Gnome H.1000
(Mk.101) 1,050 shp, first production version for use on later marks of Westland Whirlwind

Gnome H.1200
1,250 shp, the Westland Wessex uses two H.1200, as the Coupled Gnome, with a coupled gearbox with a limited power of 1,550 shp at the rotor.

Gnome H.1400
1,400 shp for the Westland Sea King HAS.1

Gnome H.1400-1
1,535 shp, uprated from the 1400 by increasing the gas-generator speed and using improved blades that can operate at higher temperatures for the Westland Sea King HAS.2.

Gnome H.1400-1T
For the Westland Commando HC.4

Gnome H.1400-2
1,660 shp for the Westland Sea King HAS.5.

Gnome H.1400-3
1,720 shp with new two-stage power turbine.

Gnome P.1000
Turboprop version of the H.1000

Gnome P.1200
Turboprop version of the H.1200

Gnome P.1400-3
Turboprop version of the H.1400-3 rated at 1,700 shp.

Gnome Mk.101

Gnome Mk.110
Handed H.1200 engines for Coupled Gnome units used in Westland Wessex helicopters.

Gnome Mk.111
Handed H.1200 engines for Coupled Gnome units used in Westland Wessex helicopters.

Gnome Mk.510
Civilianised Gnome engines.

Gnome Mk.610
Civilianised Gnome engines.

Gnome Mk 660
Used in the civilian Westland Wessex 60 helicopter

Coupled Gnome
Twin engines driving through a common gearbox to a single output.


Application: General Electric T58
Aerospatiale SA 321K Super Frelon
Agusta A.101
AgustaBell AB204B
Bell UH-1F/TH-1F
Bell X-22 (YT58)
Boeing Vertol BV-107-II
Boeing CH-46 Sea Knight
Fairchild VZ-5 (YT58)
Kaman SH-2 Seasprite
Piasecki XH-21D Shawnee (Model 71)
Sikorsky SH-3 Sea King
Sikorsky HH-3B/C/E/F
Sikorsky HH-52 Seaguard
Sikorsky S-61L/N
Sikorsky S-62
Sikorsky S-67
Sikorsky S-72


Applications: Rolls Royce Gnome
Agusta A.101
AgustaBell AB204B
Agusta-Bell 205BG
Kawasaki KV-107 (Swedish Navy only)
Saunders-Roe SR.N6 hovercraft
Westland Sea King and Commando
Westland Wessex
Westland Whirlwind


Type: Free power turbine turboshaft
Length: 55 in (1,397 mm)
Diameter: 16 in (406 mm)
Dry weight: 285 lb (129 kg) without reduction gearbox, 391 lb (177 kg) with reduction gearbox
Compressor: 10 stage axial-flow compressor with variable inlet guide vanes + variable incidence stators in first three stages
Combustors: Annular combustion chamber with 16 burner nozzles on two manifolds
Turbine: 2x gas generator power turbine stages + 1x free power turbine stage
Fuel type: Aviation kerosene
Maximum power output: 1,250 hp (932.12 kW)
Overall pressure ratio: 8.3:1
Specific fuel consumption: 0.64 lb/hp/hr (0.389 kg/kW/hr) at maximum continuous rating
Power-to-weight ratio: 6.1 hp/lb (10.024 kW/kg) without reduction gearbox


Gnome H1400-1
Type: Turboshaft
Length: 54.8 in (1392 mm)
Diameter: 22.7 in (577 mm)
Dry weight: 334 lb (151.5 kg)
Compressor: Ten-stage axial flow
Combustors: Annular
Turbine: Single-stage compressor turbine, two-stage power turbine
Maximum power output: 1,500 shp (1,119 kW)
Overall pressure ratio: 8.4:1
Power-to-weight ratio: 4.5 shp/lb



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