Starting up the jets

[jrpilot]

does anyone know how long it takes a pilot to start a jet up..it takes me to start up the Wilco CRJ about  5 minutes (I just started with her again and have to get used to the button)

I have some DVDs of start-ups and the pilots just fly thorugh it I know they just didn't learn to fly yesterday but DAMMM they are fast...calling N1, N2 rotation...etc

[Craig.]

In the end its like starting a car. Once you know how its not difficult. Thats why it takes hundreds of hours of learning to fly to get to the point.

[jknight8907]

I think it depends on the particular jet. (jet=engine, not jet=the plane)

Basically what happens is the turbine is spun up using either an electric starter or bleed air. After the turbine reaches a certain N1 percentage, fuel is turned on and ignited by the ignitors. After the jet is running, the ignitors are turned off. It's important that the N1 percentage gets high enough before combustion is initated, or else there isn't enough air moving through the turbine and you basically have a Jet A-fueled furnace burning in there; this is known as a 'hot start' and depending on how bad it is, can be very very expensive to fix.

[Nexus]

Good explanation, but you are confusing the N1 with the N2 (HP compressor)

It's the N2 RPMs that has to be high enough to provide sufficient airflow to support combustion. Usually you'll add fuel at around 20-25% N2 (depending on engine)
If the compressor can't supply enough air and you add fuel, chances are that you'll get an engine hung start...ummm...and that's not funny aswell  :)