Gnome Turboshaft Engine

(AKA General Electric T58)

I recently was offered a Gnome helicopter engine for 50 UKP. Being pretty naive when it comes to surplus aircraft engines, I guessed it might be a 'scrapper', but didn't expect something, described as 'an engine', to be missing its rotor !

However, I decided to part with my money for three reasons:

1 - I would learn quite a lot about this particular engine.

2 - I might be able to use some of the parts (like the oil cooler)

3 - Since it would never run, I could have a lot of satisfaction from dismantling it, and be able to admire the technology involved.

Complete Gnome

Unfortunately, my 'engine' does not look much like the above !

However, it did look like this, before I took it to pieces. Bear in mind, this engine would be capable of around 800 shp, and it is small. This section is no more than 1.2m in length and 400mm in diamter !

Part-GnomePart Gnome, other side

The left-hand image shows the electrical loom, the power turbine TIT thermocouples (8 off) at the base, and the ancillaries (fuel pump, oil pump etc) at the top right. The right-hand image shows the variable compressor blade actuator mechanism, with the ancillaries at the top left.

The ancillaries removed. There is a fuel pump and flow controller, oil pump, four section oil scavenge pump, plus a few other bits which I have yet to identify !


I was particularly keen for DTT list subscribers to see this. This combustor is about 300mm in diameter, by 300mm long. It has 16 tiny fuel atomisers, which supply enough fuel to heat nearly 5.5kg of air per second to over 800C.

Probably about 30 times your average DTT air flow (especially my rig !). The energy density is staggering !


This (poor) image is the power turbine nozzle guide vane assembly. The blades are hollow, and are cooled by air bled from the compressor.

Turbine nozzle guide vane (NGV)

The oil is cooled by the fuel flow in this minute heat exchanger.

Fuel/oil heat exchanger

I learnt a lot about this engine from an Air Publication document, kindly lent to me by Ian Bennett. This wonderful book covers every aspect of the Gnome and its control system. Thanks Ian !!

Ian Bennett's turbine hobby pages

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