WIPERs
Joined: Nov 1999
Aviation Qualifications: ATPL
Posts: 3,150
Likes: 744
From: UK
I suspect it is because that's the way it has always been done, until one day, someone said "hang on a minute.......why not park them vertically and save drag, noise and also the torque effect of the drag on the motor and pivot, thereby allowing a smaller and lighter motor/gearbox?"
If aircraft manufacturer(s) were seeking to reduce as much drag and weight as possible in the pursuit of greater efficiency, then even horizontally parked wipers would come under scrutiny.
If aircraft manufacturer(s) were seeking to reduce as much drag and weight as possible in the pursuit of greater efficiency, then even horizontally parked wipers would come under scrutiny.
Joined: Aug 1998
Posts: 2,033
Likes: 14
From: London, UK
McDonnell Douglas did this on the MD-11 when compared to the DC-10 when they were trying absolutely everything to reduce drag to try and meet the 11's fuel performance guarantees - which it never did.
Joined: Dec 2003
Posts: 2,349
Likes: 845
From: Tring, UK
I always look out the front window on the 777 and wonder how much energy it takes to push the wipers around the world at M0.84. Probably not much in comparison to the rest of the airframe but as a glider pilot things like that make me wince...
Joined: Jun 2014
Posts: 1,052
Likes: 72
From: Village of Santo Poco
I suppose the other option would be to make them somehow retractable, which actually sounds good, but I imagine that would require pushing all the related complexity of the retraction mechanism around the world.
Joined: Apr 2004
Posts: 2,166
Likes: 86
From: Planet Earth
I thought MD did manage to meet it's performance guarantee's with the MD11, eventually, in fact I think it exceeded them.
Too late by the time they achieved that however, losing the Singapore order was a result of those early shortfalls and it was never a big hit in the passenger world.
Its atrocious safety record didn't help.
Too late by the time they achieved that however, losing the Singapore order was a result of those early shortfalls and it was never a big hit in the passenger world.
Its atrocious safety record didn't help.
Joined: Dec 2000
Posts: 2,132
Likes: 3
From: on the golf course (Covid permitting)
Full Wings
Why would you use the wipers at M0.84
You only need the wipers for a short period during take off and on approach to land.
I always look out the front window on the 777 and wonder how much energy it takes to push the wipers around the world at M0.84. Probably not much in comparison to the rest of the airframe but as a glider pilot things like that make me wince...
You only need the wipers for a short period during take off and on approach to land.
Joined: Dec 2003
Posts: 2,349
Likes: 845
From: Tring, UK
Well, that’s the English language for you!
Of course I don’t use the wipers at M0.84 - everyone knows that M0.82/280kts is the limit...
To elucidate: even when not in use, they stick out in the breeze. How much extra fuel is burnt over the lifetime of the aircraft compared to a setup where they retracted? On some cars they retreat into more stagnant air in the scuttle area.
It’s also annoying when the speed and clamping forces allow resonance and the whole thing loudly vibrates for much of the flight.
Of course I don’t use the wipers at M0.84 - everyone knows that M0.82/280kts is the limit...
To elucidate: even when not in use, they stick out in the breeze. How much extra fuel is burnt over the lifetime of the aircraft compared to a setup where they retracted? On some cars they retreat into more stagnant air in the scuttle area.
It’s also annoying when the speed and clamping forces allow resonance and the whole thing loudly vibrates for much of the flight.
Joined: Jul 2013
Aviation Qualifications: Non-Aircrew
Posts: 5,682
Likes: 3,347
From: Everett, WA
Mazda did that with the rear window wiper on my RX-7 30 years ago to reduce noise and drag.
I'm somewhat surprised it's taken the aircraft manufactures this long to catch up
I'm somewhat surprised it's taken the aircraft manufactures this long to catch up