787 Question
 

I understand most systems are driven electrically, are there ANY that are hydraulically powered?

Is there a hydraulic system of any kind on the aircraft?!

I understand the cockpit may have Liquid Crystal Displays

(I know, coat, hat, cautiously exit...)

Far as I know hydraulics will still be on board. It's the pneumatics that are being replaced by electrics.

787
 

Reading through some of the information, it says the landing gear extension and retraction will be electrically operated and I know they will be using electric brakes.

What about flap/slat and primary flight control operation?

Primary flight controls will be combination hydraulic/electric. Engines are rumoured to be sans hydraulic pumps. Not sure about flaps primary drive, but read somewhere that there is an integrated electric motor that varies the trailing edge shape of the wing for cruise drag reduction. Try a search on Parker Hannifin (sp?), Hamilton Sundstrand and Moog for more on the 787 hydraulics.


Electric braking sounds very interesting. Some sort of motor driven screw actuator would be my guess since a pure magnetic caliper would ,while quick, be heavy given the forces required. Goodrich has the contract for this item.

Rumour has it the electric brakes fitted to the 787 are so good Boeing are going to offer it as a mod to 747.....:ok:
Here is a link to how they work...

http://www.messier-bugatti.com/IMG/pdf/frein_en.pdf

Fascinating Bolty!

Link with minor adjustment. :ok:

Thanks, Vapilot. When I saw this thread, I thought of dynamic braking as in locos and the 787 would have a bunch of coils on top dissipating the heat.

GF

Flight controls should be along the lines of the 777 only 'more modern' what ever that means really.... probably a couple of hydraulic systems at least but with better plumbing?!
The variable trailing edge business I think is being operated via electrics to the flaps on the AA 777 testbed however not so sure about on the real deal.

It says here that you can run 400 homes from the 1.45MW a 787 kicks out in electrical power so I guess anything that can be electrified will be.

Interesting about those brakes, also heard about this 'brake to vacate' thing where you select your runway exit and provided you put the machine down in a sensible place it'll slow you as required to leave at the chosen exit, life gets a little easier...:ok:

PP

Wonder what happens when you have a dual generator trip, no APU and are down to battery power???

Well, with the back-up generators, that would leave you with two....:}

A battery backup brake power supply or BBBPS perhaps
:ok:

From a Boeing Presentation I attended I understood there will be some small local hyraulic systems, electrically powered, such as for L/G operation, and flight controls. 5000PSI I think was the pressure they were talking about...

Flight international did a fairly thorough description of the aircraft a month or so back, I would reccommend visiting their site to have a read.

http://www.flightglobal.com/Articles...et+of+the.html