engine start

[TB2]

Just out of curiosity, why don't A/C with two or more engines seem to start them all at once?

[Andrew D. the Jolly Rogers guy]

Well, if you had a car with two engines you'd start them independently too. Besides...wiring them to start at once sounds like a good recipe for total overload of the system, and not just the battery providing the starting power. In fact, that may be a root right there.

[A-4Silverfox]

Batteries; ever note on the B-24, the first engine started is Number Three, 'cause that's where the main battery and generator are located.

[Liberator24]

Here is some worthless trivia...

The Incredible Hulk roller coaster at Universal here in Orlando has its on power plant to power the Mag-Lev system that hurls the caoster up the first hill....because of the drain.

Imagine the drain from one engine of the -24 on a battery, or two.....

[Edgar]

When starting, the pilot needs someone, on the ground, to watch out for fire, etc. He can't watch both at once.

Edgar

[Hawk10]

Batteries; ever note on the B-24, the first engine started is Number Three, 'cause that's where the main battery and generator are located.

Actually, all four engines have generators and the batteries are in the fuselage under the main flight deck just forward of the bombays - #3 is started first because it's the only engine with a hydraulic pump (there is an electrically powered aux hydraulic pump in the fuselage but its use was restricted to emergency use only and of course the obligatory hand hydraulic pump). That info is based upon the dash one (Flight Manual) and the B-24J I helped maintain for 5 years.

And even on a twin engined ac, you don't just push the button to start it - goes something like this:

Master/aux power - On; Mags - Off; throttle - cracked; Fuel - On; Boost Pump - on, Primer - On for 15 to 20 seconds; Then: Starter - Engaged; Count 12 blades of rotation and then Mags - Both On (After about 3 blades, fuel should start coming out of the blower drain - if it doesn't, it usually means you have a lean start and you will usually get a loud boom and a rather large flame belching out of the carb intake when you turn the Mags on) -When the engine starts you move the mixture smoothly but quickly to the Full Ritch position and disengage the starter - set the rpms between 900 and 1000 and check that the oil pressure has started to rise 40 to 60 second after start (if it doesn't, you gotta shut down and figure out what's wrong); then turn off the boost pump - and if it's a cold engine, the oil pressure will go off the dial on the high side - now you've got to wait 5 to 10 minutes until the engine warms up enough for the oil to thin out enough to fall into the normal operating range (usually somewhere aroung 80 psi) so you can advance the throttle to 1200 to 1300 rpms so the generator will come on line - then you go thru the same drill for each of the other engines

And you always want to have aux power to start cause there isn't an aircraft battery out there that will stay up for more than 3, maybe four tries to get an engine started without help - it's very easy to get a fire started when starting a radial and the easiest way to put it out is to get the engine started - most batteries tend to go away just about the time you have a stack fire or an intake fire - Radials are great but they can sometimes scare you to death when starting

Edited October 21, 2006 by Hawk10

[Spongebob]

All sorts of reasons:

Battery Power, or lack thereof, like the King Air. You start one side, then need to charge the battery back up before starting the other.

Or bleed air: in the E-2 with no APU, there's only enough air to start one at a time. However, the H-60 and the C-130J's apu can crank all the engines at once.

So, depends on the plane.

And airliners start during/just after the pushback, so firefighting personnel are not universally used...

HTH

Spongebob

Edited October 21, 2006 by Spongebob

[bentwaters81tfw]

The Vulcan had a facility for rapid/simultaneous engine start. An external power source, called a palouste, was kept plugged in on alert a/c. It was possible for the a/c to be airborne in under 4 minutes from the order to scramble. The sound of 4 Olympus engines on rapid start from cold is VERY impressive

[Skull Leader]

I believe the B-1s have a similar "cold start" function activated by a large, red button located on the nosewheel strut... I can just imagine the power it takes to get 4 of those GE F-110 turbines cranking so quickly.