747400sp
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B-52 Start Up

Wed May 30, 2007 7:43 am

I recently saw a B 52 in action for the first time that I could remeber. When the A/C started it engines, the ground crew hook a cord or hose from an APU cart, to the number 3 and 4 engines. The pilot started the number 3 and 4 pushing them to near full power, them the ground crew unhook the cord or hose and the the pilot push the number 3 and 4 engines to near full power agine, so they could start up number 5 and 6, then the pilot push number 3,4, 5 and 6 to near full, to start up 1 and 2. Then the pilot push all running engines to near full so they could start up 7 and 8.
Is this the normal way to start up a B52, or did they do this because the base that they was visiting was a fighter base, and may not have had eough APU carts to start up all eight of this B-52H engines?

PS: I have to say, after seeing and hearing a BUFF in person. There only few word to destribe a BUFF, A CLASSIC BEAST!  Big grin
 
MDorBust
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RE: B-52 Start Up

Wed May 30, 2007 8:21 am

There's only one real way to witness a B-52 start.

The cartridge start. Eight at a time baby!
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USCGC130
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RE: B-52 Start Up

Wed May 30, 2007 10:24 pm

It strikes me as unlikely that engines 3/4 would need to be brought upnto near full power in order to supply enough bleed air to start any ofnthe other engines. Plus, having that much asymmetrical thrust wouldnprobably place undesirable stress on the airframe.
 
ebj1248650
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RE: B-52 Start Up

Wed May 30, 2007 10:32 pm

Quoting Uscgc130 (Reply 2):

You bring those two engines up to full power to get enough bleed air to start the other engines. I'm having a hard time picturing why all six running engines would need to be brought to full power to start the last two though.

On the KC-135A, one engine at full power could be used to provide bleed air to start the other three.
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Venus6971
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RE: B-52 Start Up

Wed May 30, 2007 11:11 pm

Quoting EBJ1248650 (Reply 3):
You bring those two engines up to full power to get enough bleed air to start the other engines. I'm having a hard time picturing why all six running engines would need to be brought to full power to start the last two though.

Because they started two at a time, usally at a Buff base you had a ma1a , -60, or -95 ground cart hooked to the inbd pods and started them first then you went up in power to get them at least 35 to 40 psi of bleed air to turn the the other 4 starters, the only time you used carts was during alert wartime siop or exercises, or just one engine when the pilot needed it for training. That system was mx intensive because of all the breach cleaning and continuity checks that was required.
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solnabo
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RE: B-52 Start Up

Thu May 31, 2007 11:04 pm

Are the BUFF ever gonna swap engines ´cuz they´re to be around til 2045 according to USAF?

GE PW RR maybe?

Micke//  Confused
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prebennorholm
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RE: B-52 Start Up

Fri Jun 01, 2007 9:16 am

Quoting Solnabo (Reply 5):
Are the BUFF ever gonna swap engines ´cuz they´re to be around til 2045 according to USAF?

Huh, I could see the buff one day with four CFM56-5C4 replacing the eight PW TF-33 (the 34klbs engine used on A340-300). Also because other CFM56 versions (F108) are already in widespread use by the USAF.

But it's an awful lot of money. And the tanker replacement has higher priority and seems to last for ages.

Probably nothing will happen on the southern side of 2020. Plenty of former civil JT3Ds are sitting (or have been sitting) on KC-135Es and may "free of charge" soldier on on the buff.

But I have doubts. The TF-33 keeps its thrust much better at very high altitudes than any modern high bypass ratio turbofan engine. That may be a quality which has higher priority than longer unrefueled range.

Those birds are not flying 16 hours a day 7 days a week, so fuel cost is hardly a major consideration.

We can also hope that world peace breaks out first, and the buffs can be beercanned instead.
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kc135topboom
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RE: B-52 Start Up

Sat Jun 09, 2007 7:31 am

Quoting Prebennorholm (Reply 6):
The TF-33 keeps its thrust much better at very high altitudes than any modern high bypass ratio turbofan engine. That may be a quality which has higher priority than longer unrefueled range.

That is true, low bypass engines are more effeicent at high altitudes than high bypass engines, turbojets are even better. Refueling is not a problems as long as the KC-135 is around.

Quoting Prebennorholm (Reply 6):
Those birds are not flying 16 hours a day 7 days a week, so fuel cost is hardly a major consideration.

Fuel costs are a major concern. A fully loaded B-52H (with weapons) needs about 40,000lbs of fuel per hour, at cruise. When you fly from LA or ND to Guam, then Deigo Garcia, then Afghanistan, that's a lot of fuel. (total flight time from Barksdale to Deigo is 22 hours, if you go non-stop).
 
ex52tech
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RE: B-52 Start Up

Wed Aug 01, 2007 12:39 pm

Normal start up for a BUFF is.

Start #4 to bring the LH body hydraulic system up, then open the cross bleed, apply power to #4, monitor the pneumatic manifold temp while starting #5.

#5 brings the RH body hydraulic system up to pressure, and provides you with bleed air for all the engines on the RH wing.

At this point close the cross bleed valve.

Bring #5 up to power. You can gang start 1,2,and 3 with bleed air off of #4, and 6,7,and 8 with bleed air off of #5.

Yes it is a lot of fun starting a BUFF that way, a little busy, but fun.

It's more fun firing all 8 cartridges, then shoving all 8 throttles to the idle detent, and monitoring the engines for a hot start. Only got to do that once.

Cartridge starts were hard on starters, especially on the G model, that starter wasn't any where near as tough as the starter on the TF-33 on the H model.
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