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-   -   WIPERs (https://www.pprune.org/tech-log/586645-wipers.html)

inducedrag 6th Nov 2016 10:14

WIPERs
 
For years have flown airliners with horizontal wipers now on new aircraft (B787 A350 ) see them vertical any specific reason.

Piltdown Man 6th Nov 2016 10:43

Less drag when parked.

safelife 6th Nov 2016 12:56

Less noise when parked.

BigGeordie 6th Nov 2016 13:20

But if the aircraft is parked you don't have any noise or drag.

I'll get my coat.

Lantirn 6th Nov 2016 13:51

I think that he is trolling :)

Denti 6th Nov 2016 18:00

Who? TangoAlpha?

Ok, hat and coat...

Amadis of Gaul 6th Nov 2016 22:19

Might have more to do with the shape of the windshield.

Uplinker 7th Nov 2016 16:32

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.

Groundloop 7th Nov 2016 19:54

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.

FullWings 7th Nov 2016 21:02

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...

Amadis of Gaul 7th Nov 2016 22:24

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.

stilton 8th Nov 2016 04:03

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.

TopBunk 8th Nov 2016 07:14

Full Wings


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...
Why would you use the wipers at M0.84:ugh: You only need the wipers for a short period during take off and on approach to land.

FullWings 8th Nov 2016 09:59

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.

Uplinker 8th Nov 2016 11:17

Ha ha Topbunk - you just made my day !

I think that being on the golf course you have just scored a hole in one: foot into mouth, that is. :ok:

TopBunk 9th Nov 2016 07:47

Fair point - skim reading, I guess.

BTW haven't had a hole in one (on the golf course ;)) since 2008!

EEngr 11th Nov 2016 17:33


Why would you use the wipers at M0.84
Those must be some scary looking bug splatters.:eek:

fantom 11th Nov 2016 18:46

Wipers.

It is the 11th day of the 11th month.

tdracer 11th Nov 2016 19:52

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 :E

Unregistered User 12th Nov 2016 00:17

If it's a 20 something, hot female, then sure, I'd love to wipe hers.

oceancrosser 12th Nov 2016 18:35


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
No matter how cheap a car you buy, the wipers are far better than on any airliner I have flown. 757/767 wipers. Crap. And lots of times they will not stop when switched off.

JammedStab 12th Nov 2016 20:09

The first aircraft I flew that had pretty good wipers was the 747-400. At leaast that was my experience. The 777 seems pretty good as well and someone decided to give us a nice intermittent mode. All the truboprops and old Boeings were crap.

Amadis of Gaul 13th Nov 2016 00:47

In my experience (CRJ, E170/175, A320) they produce more noise than benefit.

stilton 13th Nov 2016 04:14

Didn't the CV880 /990 use bleed air for rain removal ?


I imagine that was noisy but effective.

Capn Bloggs 13th Nov 2016 06:20

That squirty stuff in the 146 ran rings around the wipers.


I must admit the Saab has good wiper blades except the speed choices.. off, super fast or having a seizure bat**** crazy fast.
Same here on my non-SAAB! :{

Capt Fathom 13th Nov 2016 10:00

Never flown any aeroplane where the Wipers actually worked! From GA to multi-million dollar aeroplanes! Just sayin!

oceancrosser 13th Nov 2016 12:32


Didn't the CV880 /990 use bleed air for rain removal ?

I imagine that was noisy but effective.
DC-8s did have bleed (from the compressors in the nose) for rain removal. Fairly effective, but noisy as hell.

Uplinker 13th Nov 2016 16:36

The bloke who designed the wipers for the Dash 8 Q400 must have been told at 1658 on Friday "bugger, we forgot the wipers. Quick design something".

:-)

plhought 16th Nov 2016 04:11

The Q400 wipers are identical to the 'Classic' Dash.

Our outfit they usually try and stop the wipers when they are kind of vertical. Reduces noise considerably.

Still look like they are having a seizure when they are operating

FixClrEnt 16th Nov 2016 07:43

Many aircraft don't even have wipers. I know that some use a rain-dispersant coating on the 'glazing', so if that works why go to the trouble of fitting wipers in the first place?


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