787 Dreamliner cockpit noise and windshield wipers

[Check Airman]

Hi,

I was recently in the Jumpseat of a 777, and one of the pilots said the cockpit of the 787 is so quiet because the wipers are stored vertically.

I’d have thought it has more to do with the design of the nose and the fixed windows.

Can anyone point to an authoritative source on the matter?

Thanks

[e2_c]

The position of the wipers makes a huge difference. On the Q400 some pilots activate the wipers and leave them in the close to vertical which reduces the noise considerably. I don't know why the manufactures don't change the parked position to being up to reduce the cockpit noise.

[FullWings]

I’ve always wondered how much extra drag windscreen wipers create, and how a mechanism to completely stow them might save a lot of fuel. They’re like little speedbrakes sticking out into the nice laminar flow at the front of the aeroplane, and they do that for the whole sector.

Yes, it would be more mechanically complex, but you’ve already got electric motors and drivetrains. Could be as simple as having some kind of a scuttle, like you do on cars, which the wipers come up from. If it’s worth it on a car, on an aeroplane at >5x the airspeed (>25x the drag) it would seem to make even more sense...

[ni si ni no]

They’re like little speedbrakes sticking out into the nice laminar flow at the front of the aeroplane

Oh boy, after flying the Airbus for a good number of years, im now in the 737 and its frankly quite bad in that regard. Not sayin the bus is a good system but the 737.....:=

[tdracer]

They’re like little speedbrakes sticking out into the nice laminar flow at the front of the aeroplane

Oh boy, after flying the Airbus for a good number of years, im now in the 737 and its frankly quite bad in that regard. Not sayin the bus is a good system but the 737.....:=
A lot of the flight deck noise on Boeing aircraft is due to the ECS. I'd even heard Boeing test pilots who'd flown Airbus aircraft comment on how much better the flight deck ECS noise is on Airbus.
The 777 flight deck windows are basically flat - that section of the airframe ("41 Section" in Boeing speak) is common between the 757, 767, and 777. The 787 flight deck has curved windows and is aerodynamically cleaner than the 777 which would improve the flight deck noise - although I can't quantify that.

[eckhard]

Quiet enough to hear another jetliner passing 1000ft above or below in the cruise! (headset off)

[stilton]

Quiet enough to hear another jetliner passing 1000ft above or below in the cruise! (headset off)


Not sure that’s a benefit !

[Nick 1]

As i read somewhere and old Captain give the best definition of windshield wipers : a mechanical feature that convert electricity into noise .