Starting the B787

[tubby linton]

I believe the B787 does not have a pneumatic system so how do they start it?

[rudderrudderrat]

"Another fundamental architectural change on the 787 is the use of variable frequency electrical power and the integration of the engine generator and starter functions into a single unit."

boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_3.html

[forget]

From link above -

One of the primary functions of a conventional APU is driving a large pneumatic load compressor. Replacing the pneumatic load compressor with starter generators results in significantly improved start reliability and power availability.

I had to read this half a dozen times before it made any sense. Is this what they mean?

One of the primary functions of a conventional APU is driving a large pneumatic compressor. 787 engine start though electrical starter/generators allows elimination of the APU pneumatic compressor resulting in significantly improved main engine start reliability and APU (electrical) power availability.

Nope. Still not clear.

[ImbracableCrunk]

One of the primary functions of a conventional APU is driving a large pneumatic load compressor. Replacing the pneumatic load compressor with starter generators results in significantly improved start reliability and power availability.

My take: Old APUs drive a compressor. Ours doesn't. The new APU starts better and has better electrical availability.

Which component has better start and power availability is a little vague, actually.

[Fargoo]

"Another fundamental architectural change on the 787 is the use of variable frequency electrical power and the integration of the engine generator and starter functions into a single unit."

boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_3.html

Great article , thanks for sharing. I hadn't realised they were going for electric actuators on the brakes too.
It'll be interesting to see if their reliability predictions come to fruition with the generators as previous experience with the VSCF proved it was worse than a conventional IDG setup.

Good on them though, I'm looking forward to these arriving so much more than the A380.