Originally posted by ULTIMA1
Originally posted by Zaphod58
Whoops, forgot to load the CF6. But at 60 feet, 99.93% throttle the engine does not overheat. 500 it will, but at the parameters in the OP the
engine doesn't overheat.
If you set the altitude at 60 feet and run the speed up, as soon as you hit 480 you get temp warning.
Also why would the hijackers risk burning up the engines before they hit thier targets?
ULTIMA....so what if you get 'temp' warnings??
As you know, and for others to come accross this thread, the really most limiting factor, for a pilot, is EGT. It is important to know, on the
various engines we operate, what the 'starting' limit is, what is the Maximum for 5 minutes, what is the maximum for continuous operation, etc.
Along with this, is the Maximum EPR (not so much in today's Hi-bypass engines) and the MAX N1 and N2 (or MAX N3, if a Rolls-Royce engine).
Thing is, most critical number, is EGT.
We have, depending on the engine, a value for MAX Start temps, and MAX operating temps.
When an engine is being started, in a Boeing, the pilots monitor the start sequence. (airbuses are idiot-proof, today...)
Here's the sequence....we have the APU already running, assuming it is functional. (If it is inop, then that's why it is so hot inside the
So, assuming the APU is up and providing air and electrics, then the 'packs' are turned off (the packs are the air-conditioning machines...let's
now refer to them as the ACM) because, the way a jet engine is started, is by introducing compressed air into the compressor section, in order to
begin the 'spin-up'....this compressed air is usually supplied by the APU, but if the APU is inop, it can be supplied by a Ground Source, plugged
into the airplane.
Back to a normal start, during a push-back, because the APU is normal, otherwise we wouldn't be pushing back....get the logic?
a 'switch' is engaged, by a pilot, to initiate the 'start sequence'. Most modern airplanes have a magnetically held switch, so that once engaged,
it stays engaged until certain parameters are satisfied. On a B727, for instance, the pilot had to hold the switch until the engine reached a certain
point in the start sequence, then manually release it. NOW, it is more automatic....
Either way, the start is monitored by both pilots, because a jet engine can encounter a 'hung start'....where, for some reason, it does not normally
accellerate to idle, and the EGT can progress to temps that may cause damage. OR, the engine can have a 'hot start', where the EGT is increasing so
rapidly, it can cause damage, and that last one would indicate a problem ith the fuel control unit, or FCU.
So you see, it is important for the pilots to know how to start their engines...and it is sad that most don't ever comprehend what is required of an
airline pilot, they just think of them as glorified bus drivers.....and, I only offered insight into a small aspect of what pilots do....
You, as a passenger, should understand, and learn.