Fly2HMO
Posts: 7207
Joined: Sat Jan 24, 2004 12:14 pm

7E7 With Bleed Free Engines?

Thu Feb 12, 2004 9:27 am

I heard that on another post. What's the difference with those engines?
 
LMP737
Posts: 4808
Joined: Wed May 08, 2002 4:06 pm

RE: 7E7 With Bleed Free Engines?

Thu Feb 12, 2004 9:50 am

I recently saw a Boeing powerpoint presentation on the 7E7. What they mean by "no-bleed" engines is that the A/C packs will net use bleed air from the engines. Instead they will use four electrically powered turbine compressors. This will help improve reliability. On aircraft such as the 757/767 some of the biggest headaches come from problems with the bleed system.

Bleed air will still be used to start the engines and drive the Air Driven Hydraulic Pumps.
Never take financial advice from co-workers.
 
cdfmxtech
Posts: 1319
Joined: Wed Jul 05, 2000 11:37 am

RE: 7E7 With Bleed Free Engines?

Thu Feb 12, 2004 9:56 am

C'mon....Bleed problems are fun!
 
Fly2HMO
Posts: 7207
Joined: Sat Jan 24, 2004 12:14 pm

RE: 7E7 With Bleed Free Engines?

Thu Feb 12, 2004 10:12 am

ohhhh I see...

by the way, around how much thrust will they have?
 
katekebo
Posts: 678
Joined: Sat Apr 14, 2001 12:02 am

RE: 7E7 With Bleed Free Engines?

Thu Feb 12, 2004 3:36 pm

There are several reasons to go with a bleedless engine. The main one is less fuel consumption. Using bleed air for heating is not very efficient from the thermodynamic standpoint. Electrical system is more efficient so it will result in overall better fuel efficiency. The other reason is weight reduction. Less ducts and insulation. There may be other reasons (reliability).

 
NKP S2
Posts: 1665
Joined: Mon Dec 20, 1999 3:16 am

RE: 7E7 With Bleed Free Engines?

Thu Feb 12, 2004 3:52 pm

C'mon....Bleed problems are fun!

Amen, from another ATA 36 junkie. ( glutton for punishment? )

If the weight and complexity created by the use of electric TCs is on balance lower than the fuel/EGT penalty and complexity of engine/APU compressor bleeds, then why not?
 
grandtheftaero
Posts: 247
Joined: Sat Nov 29, 2003 1:05 pm

RE: 7E7 With Bleed Free Engines?

Thu Feb 12, 2004 4:53 pm

"by the way, around how much thrust will they have?"

The engine that GE is developing for the 7E7 is to be the future replacement for the CF6. So I assume that their thrust ratings are similar.

--Shane
 
Shenzhen
Posts: 1664
Joined: Wed Jun 25, 2003 12:11 pm

RE: 7E7 With Bleed Free Engines?

Thu Feb 12, 2004 6:52 pm

The only thing that bleed air will be used for is nacelle anti ice. Everything else will be electric, including the starters and hydraulic pumps. The starters will also be generators, providing power to the electric compressors, which will provide the air to the packs.

cheers
 
LMP737
Posts: 4808
Joined: Wed May 08, 2002 4:06 pm

RE: 7E7 With Bleed Free Engines?

Fri Feb 13, 2004 8:09 am

Fun like the intestinal flu.  Big grin
Never take financial advice from co-workers.

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