Combustion Sustained: Starter Motor Torque/Inertia Selection

[Bonavaero]

In selecting starter motor for a gas turbine, which minimum torque or inertia is it supposed to overcome, it that of the compressor or the turbine, or both.

 

[adexkola]

I would assume it would be the turbine. The gearbox would play an important role in getting the engine started.

 

[minger]

If you're spinning the shaft to start it, then you'll obviously need something to spin the shaft...the whole thing. In addition to that, the blades will be moving air, so that will increase the torque required.

 

[adexkola]

I would assume once the shaft is spinning at a moderate speed and the gas is let out to the combustor, the process becomes self sustaining?

 

[minger]

Oh yea. Jet engines are super easy to design. You'll be adding a high-pressure spool in a month.

edit: I should add this post may contain extreme levels of sarcasm.

 

[sorter]

I assume starter motor are predominantly for compressors (even though turbine is attached from a coomon shaft) ; because after combustion start turbine start to move & carryout combustion one must move compressor such that air is sucked & compressed to combustor. However once process is self-sustained its the opposite; turbine movement causes compressor to move!