User avatar
nitepilot79
Topic Author
Posts: 771
Joined: Tue May 20, 2008 9:10 pm

Why Are Airliners' Wipers So Noisy?

Mon Apr 04, 2011 10:27 pm

I'm curious why the flight deck windshield wipers in basically every cockpit video I've ever seen been so loud? (airliners mostly) although not just loud, but nerve-racking as well. Is this intentional? Any thoughts?
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Why Are Airliners' Wipers So Noisy?

Mon Apr 04, 2011 10:55 pm

Maybe MX needs to start using the new Bosch superblades that they are selling at auto parts stores  
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
User avatar
nitepilot79
Topic Author
Posts: 771
Joined: Tue May 20, 2008 9:10 pm

RE: Why Are Airliners' Wipers So Noisy?

Mon Apr 04, 2011 11:14 pm

Quoting KELPkid (Reply 1):
Maybe MX needs to start using the new Bosch superblades that they are selling at auto parts stores

Right on, how about "Aqua Tread" for the tires! Does Goodyear even sell that brand anymore   
 
Fly2HMO
Posts: 7207
Joined: Sat Jan 24, 2004 12:14 pm

RE: Why Are Airliners' Wipers So Noisy?

Mon Apr 04, 2011 11:53 pm

Quoting KELPkid (Reply 1):
Maybe MX needs to start using the new Bosch superblades that they are selling at auto parts stores

Well at my former airline they used Rain-X on the windshields 
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Why Are Airliners' Wipers So Noisy?

Tue Apr 05, 2011 5:11 am

Quoting nitepilot79 (Thread starter):
I'm curious why the flight deck windshield wipers in basically every cockpit video I've ever seen been so loud?

Are you talking motor noise or wiper blade noise?

In order to prevent chatter in the airstream, the wipers are pretty heavily sprung (they push hard against the glass)...I think that's why the wipers blades themselves are so squeaky. As for the motors...lowest bidder?

Tom.
 
User avatar
DocLightning
Posts: 19603
Joined: Wed Nov 16, 2005 8:51 am

RE: Why Are Airliners' Wipers So Noisy?

Tue Apr 05, 2011 6:21 am

Quoting tdscanuck (Reply 4):

In order to prevent chatter in the airstream, the wipers are pretty heavily sprung (they push hard against the glass)...I think that's why the wipers blades themselves are so squeaky. As for the motors...lowest bidder?

I'd assume the motors have to be pretty beefy if they are going to move the wipers against the airstream.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
330guy
Posts: 239
Joined: Thu Nov 18, 2010 9:51 am

RE: Why Are Airliners' Wipers So Noisy?

Tue Apr 05, 2011 10:28 am

Iv always wondered why with all the billions pumped into the development of aircraft technologies and systems...ect that wipers still sound like a machiene from "Charlie and the Chocolate Factory"
Aircraft flown: a300/10/20/21/30/40, b727/37/47/57/67/, DC9, MD80-90, l1011, f50, atr42/72, shorts360, pc12
 
musang
Posts: 788
Joined: Sun Apr 08, 2001 4:11 am

RE: Why Are Airliners' Wipers So Noisy?

Tue Apr 05, 2011 11:14 am

Apart from having to be rather powerful, the other factor is that they're located just a couple of feet ahead of the pilot's face and the noise/vibration transmits via the adjacent structure, i.e. the cockpit windscreen surrounds.

My perception is the noise is 95% motor, 5% blades on glass, i.e. they don't squeal. Very occasionally they judder briefly but soon sort themselves out due to the Tom-mentioned arm-pressure.

Those in the RJ 100/146 were so noisy they were almost a threat to effective conversation, but they did work. The 146 also had screen washer jets, with a push-and-hold button overhead near the wiper switch. There were not many occasions where this feature proved valuable. You had to wait a good few seconds for the fluid to rise from the pump in the avionics bay, because the non-return valve was rubbish.

ATR wipers were not so noisy, but invariably ineffective, leaving many streaks. Hopefully the current ones are improved.

Regards - musang
 
jetstar
Posts: 1366
Joined: Mon May 19, 2003 2:16 am

RE: Why Are Airliners' Wipers So Noisy?

Tue Apr 05, 2011 9:26 pm

On the Lockheed JetStar, the windshield wiper system, was very loud, so we never used it for landings, they could be used in flight with a speed restriction of 205kts, and occasionally only on the low setting while taxiing. Each wiper blade had it own motor, located just above the pilots outboard ear, from this motor a flexible shaft extended forward to the converter, which converted the rotary motion of the shaft to the oscillating motion of the wiper arms and this converter was located just inside where the wiper shaft attached to the converter.

In this photo, you can see both wiper arms in the parked position with the shaft extending slightly from the upper portion of the windshields.


View Large View Medium
Click here for bigger photo!

Photo © Rolando Criniti



Both wiper blades were controlled by one rotary switch located above the captains head, the switch had 4 positions, low, high, off and park. When you shut off the wipers, the blades remained in whatever position they were in and you had to reach up and move the rotary switch to the park position to park the wiper arms, the park position on the switch was spring loaded and when released the switch returned to the off position

One time while flying with the Chief Pilot, we were descending out of around 15,000 feet slowing down from just about 300 kts when for some reason the captains side wiper arm moved slightly off of the parked position, creating some noise. So the chief pilot reached up and moved the rotary switch to the park position, which was clearly marked with the 205 kt speed restriction, almost instantly the wiper arm went from the inboard position on the wind screen to the outboard position and the noise was incredible, we could hardly hear each other. He immediately slowed the airplane down which reduced somewhat the noise and when we got to about 180 kts, he tried again to park the wiper arm, which would not move from its outboard position.

After we landed I borrowed a ladder from the fuel truck and I was able to move the wiper arm back and forth. The shaft that holds the wiper arm to the converter was totally stripped out and the only thing holding the wiper arm onto the converter was the small bolt on the end of the shaft. Since I always carried a small toll box with me, I unbolted the wiper arm and removed it and we flew the rest of the trip minus one wiper arm. We were very lucky that day that the shaft remained attached to the converter, had it let go the wiper arm would have probably gone through number 2 engine.

Just another day in the life of a corporate flight department.

JetStar
 
Viscount724
Posts: 18834
Joined: Thu Oct 12, 2006 7:32 pm

RE: Why Are Airliners' Wipers So Noisy?

Tue Apr 05, 2011 9:58 pm

Why didn't the bleed air rain removal system used on the DC-8, which has no windshield wipers, become more popular? Did it not work effectively? Did any other airliners use a similar system?

I'm guessing there must have been some negatives since Douglas reverted to wipers on the DC-9.

There's a diagram of the DC-8 system in Section 1.6.5 of the following accident report covering an Arrow Air DC-8-62 freighter overrun at SIN in 2002. It's also mentioned in Section 2.4 in the Analysis section. The accident occurred during heavy rain.
http://www.icao.int/FSIX/sr/reports/02005270_final_report.pdf
 
mrskyguy
Posts: 309
Joined: Thu Aug 28, 2008 7:13 pm

RE: Why Are Airliners' Wipers So Noisy?

Wed Apr 06, 2011 3:44 am

Quoting Viscount724 (Reply 9):

Why didn't the bleed air rain removal system used on the DC-8, which has no windshield wipers, become more popular? Did it not work effectively? Did any other airliners use a similar system?

I'm guessing there must have been some negatives since Douglas reverted to wipers on the DC-9.

Ahh, I forgot about that.. that's so Douglas.  

Probably because anything involving bleed air is both A) more complicated to develop and maintain, B) because its complexity was likely more expensive to maintain and C) because bean-counters hate anything driven by bleed air.  
"The strength of the turbulence is directly proportional to the temperature of your coffee." -- Gunter's 2nd Law of Air
 
Dufo
Posts: 796
Joined: Tue May 18, 1999 2:41 am

RE: Why Are Airliners' Wipers So Noisy?

Sun Apr 10, 2011 6:59 am

I am almost scared to use high speed mode of wipers on our Saab 340's as they sound they're going to depart their mounting bolt. But they do work properly when you need them..
I seriously think I just creamed my pants without any influence from any outside variables.
 
User avatar
Starlionblue
Posts: 17053
Joined: Fri Feb 27, 2004 9:54 pm

RE: Why Are Airliners' Wipers So Noisy?

Sun Apr 10, 2011 10:43 am

Quoting musang (Reply 7):
ATR wipers were not so noisy, but invariably ineffective, leaving many streaks. Hopefully the current ones are improved.

It's funny how the ATRs seem to be almost universally revised by pilots. I believe Patrick Smith (of "Ask the Pilot") referred to it as an engineering marvel with fantastic tech, making it totally unsuited for its mission.

Quoting jetstar (Reply 8):
One time...

As has been said on these boards before, every time jetstar starts a paragraph like that, you know you're in for a treat.

Quoting MrSkyGuy (Reply 10):
Quoting Viscount724 (Reply 9):

Why didn't the bleed air rain removal system used on the DC-8, which has no windshield wipers, become more popular? Did it not work effectively? Did any other airliners use a similar system?

I'm guessing there must have been some negatives since Douglas reverted to wipers on the DC-9.

Ahh, I forgot about that.. that's so Douglas.

Probably because anything involving bleed air is both A) more complicated to develop and maintain, B) because its complexity was likely more expensive to maintain and C) because bean-counters hate anything driven by bleed air.

As you say, typical Douglas. It willbe the most fabulous solution ever devised. Unfortunately the cost will be to match.

Quoting jetstar (Reply 8):
On the Lockheed JetStar, the windshield wiper system, was very loud, so we never used it for landings, they could be used in flight with a speed restriction of 205kts, and occasionally only on the low setting while taxiing. Each wiper blade had it own motor, located just above the pilots outboard ear, from this motor a flexible shaft extended forward to the converter, which converted the rotary motion of the shaft to the oscillating motion of the wiper arms and this converter was located just inside where the wiper shaft attached to the converter.

What idiot came up with that? Seem designed to break down. 
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
jetstar
Posts: 1366
Joined: Mon May 19, 2003 2:16 am

RE: Why Are Airliners' Wipers So Noisy?

Sun Apr 10, 2011 4:06 pm

Quoting Starlionblue (Reply 12):
Quoting jetstar (Reply 8):
On the Lockheed JetStar, the windshield wiper system, was very loud, so we never used it for landings, they could be used in flight with a speed restriction of 205kts, and occasionally only on the low setting while taxiing. Each wiper blade had it own motor, located just above the pilots outboard ear, from this motor a flexible shaft extended forward to the converter, which converted the rotary motion of the shaft to the oscillating motion of the wiper arms and this converter was located just inside where the wiper shaft attached to the converter.

What idiot came up with that? Seem designed to break down.

Corporate jets, unlike airliners have smaller cockpits and space is tight. My main guess is that there was no room right near the wiper arm to put the motor there, so they put the motor in an area with more room and used the flexible drive shaft to power the wiper arms.

In all my years on the JetStar, I never heard of a mechanical problem with the windshield wiper system, unless you do what the idiot chief pilot I worked for did, operate the wiper system 100 kts above the placarded maximum operating speed.

JetStar
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Why Are Airliners' Wipers So Noisy?

Sun Apr 10, 2011 10:55 pm

Quoting Starlionblue (Reply 12):
Quoting Starlionblue (Reply 12):
What idiot came up with that? Seem designed to break down.

I don't know, but I think when he was done at Lockheed, he moved to Detroit and designed the vacuum wipers in 1960's era Ford trucks and then moved on to GM, ending his career with the "suicide" wipers on the Chevy Lumina (wipers whose arcs crossed each other, and when they get old, start colliding, wherein they either strip gears in the wiper mechanism or blow the wiper motor fuse) 
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
Fly2HMO
Posts: 7207
Joined: Sat Jan 24, 2004 12:14 pm

RE: Why Are Airliners' Wipers So Noisy?

Mon Apr 11, 2011 2:05 am

Quoting Viscount724 (Reply 9):
Did it not work effectively? Did any other airliners use a similar system?

I don't think I've ever heard of any airliner with such a system. Almost all the Cessna Citations use a bleed air system for their windshields. While primarily for anti/deicing purposes, they have a function for increased airflow during rain. But I hear they aren't too effective and are extremely noisy. The distinctive blisters almost all Citations have right below the windshield are the covers for the bleed air system.

Who is online

Users browsing this forum: skyhawkmatthew and 14 guests