Re: Thrust in idle engines

From: (TriStar500)
Organization: America Online, Inc. (1-800-827-6364)
Date:         03 Nov 95 04:23:14 
References:   1
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>When an engine is "idle" (eg: when aircraft awaiting takeoff, when
>finally parks at the gate etc), how much thrust is being generated ?

Depends on the engine but I believe a PW 2037 puts out about 1,200 lbs of
thrust at ground idle.

>If brakes are not applied, will the aircraft start moving right away with
>engines "idling" ?

Depends on how heavy the airplane is.

>Also, in a previous posting, someone said that without an APU, an
>would require power and "air" from the ground to start its engine. Are we
>talking about compressed air ? What for ?

The compressed air drives the air-turbine motors that turn the engine for

>Also, why are DC9s and 727s capable of backing up from the gate without
>pushed ? Is it a technical or legal consideration ? (eg: engines being
>enough away from terminal for noise control etc).

I think it's mainly a technical consideration. The high-mounted engines on
the DC9 and 727 are less likely to get FOD damage then the low engines on
a 737.