Jet engine air starter

The Jet Engine project was one of the more eye opening projects that i have ever completed - the shear power and energy produced by an engine of this type is unbelievable

until it is witnessed first hand. This type of Miniature Jet Turbine was a first generation attempt at obtain a usable Jet engine for model aircraft and used a Turbo Charger Turbine and Compressor.

My MK2 Jet self sustains with the correct exhaust temperature but with little use able thrust - it has been retired as "show your friends" piece that sits on the shelf.

Many variations of aircraft engine starting have been used since the Wright brothers made their first powered flight in 1903. The methods used have been designed for weight saving, simplicity of operation and reliability. Early piston engines were started by hand, with geared hand starting, electrical and cartridge-operated systems for larger engines being developed between the wars.

Gas turbine aircraft engines such as turbojets , turboshafts and turbofans often use air/pneumatic starting, with the use of bleed air from built-in auxiliary power units (APUs) or external air compressors now seen as a common starting method. Often only one engine needs be started using the APU (or remote compressor). After the first engine is started using APU bleed air, cross-bleed air from the running engine can be used to start the remaining engine(s).

Hand starting of aircraft piston engines by swinging the propeller is the oldest and simplest method, the absence of any onboard starting system giving an appreciable weight saving. Positioning of the propeller relative to the crankshaft is arranged such that the engine pistons pass through top dead centre during the swinging stroke.

This rather unusual looking engine is a Hants and Sussex Stad 250 air producer. It is identical to the gas turbine in my air start cart and I have obtained it with the sole purpose of providing additional air to start the RB211. I had a suspicion that I may need two air producers to spool up the RB211 to the required rpm and after a few tests this indeed proved to be the case.

This turbine engine is essentially the Engine Change Unit (ECU) from the start cart and as such does not have the associated ancillaries such as the exhaust muffler, fuel tank and control panel. I will have to build all these up and mount the engine on a wheeled frame.

Originally the engine would have been in a trolley as mentioned and these were used by the RAF to start aircraft such as the Buccaneer or the Nimrod.It is rated at 250 HP, hence the name, and produces about 120 lbs of air per min at 50 psi. They are not the greenest of engines in terms of fuel efficency and easily drink 10 gallons of Jet A1/kerosene per start cycle that usually lasts about 15 mins! As I understand it they were used as an alternative/replacement for the earlier Palouste air starters although I could be wrong!

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