nitepilot79 From Turkey, joined May 2008, 248 posts, RR: 0 Posted (2 years 1 month 2 weeks 1 day ago) and read 4667 times:
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?
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 81 Reply 4, posted (2 years 1 month 2 weeks 18 hours ago) and read 4381 times:
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?
DocLightning From United States of America, joined Nov 2005, 16803 posts, RR: 57 Reply 5, posted (2 years 1 month 2 weeks 17 hours ago) and read 4333 times:
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.
330Guy From Ireland, joined Nov 2010, 453 posts, RR: 2 Reply 6, posted (2 years 1 month 2 weeks 12 hours ago) and read 4243 times:
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"
musang From United Kingdom, joined Apr 2001, 754 posts, RR: 7 Reply 7, posted (2 years 1 month 2 weeks 12 hours ago) and read 4223 times:
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.
jetstar From United States of America, joined exactly 10 years ago today! , 1523 posts, RR: 10 Reply 8, posted (2 years 1 month 2 weeks 1 hour ago) and read 3967 times:
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.
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.
Viscount724 From Switzerland, joined Oct 2006, 21453 posts, RR: 24 Reply 9, posted (2 years 1 month 2 weeks 1 hour ago) and read 3942 times:
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 From United States of America, joined Aug 2008, 1203 posts, RR: 3 Reply 10, posted (2 years 1 month 1 week 6 days 19 hours ago) and read 3799 times:
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 From Slovenia, joined May 1999, 751 posts, RR: 4 Reply 11, posted (2 years 1 month 1 week 2 days 16 hours ago) and read 3349 times:
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.
Starlionblue From Hong Kong, joined Feb 2004, 15867 posts, RR: 66 Reply 12, posted (2 years 1 month 1 week 2 days 12 hours ago) and read 3293 times:
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.
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." - from Citadel by John Ringo
jetstar From United States of America, joined exactly 10 years ago today! , 1523 posts, RR: 10 Reply 13, posted (2 years 1 month 1 week 2 days 7 hours ago) and read 3230 times:
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.
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 From , joined Dec 1969, posts, RR: Reply 15, posted (2 years 1 month 1 week 1 day 21 hours ago) and read 3045 times:
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.
Sponsor Message: 
From Turkey, joined May 2008, 248 posts, 
From United States of America, joined Nov 2005, 5929 posts, 
From Canada, joined Jan 2006, 12709 posts, 
From Ireland, joined Nov 2010, 453 posts, 
From United Kingdom, joined Apr 2001, 754 posts, 
, 1523 posts, 
From Switzerland, joined Oct 2006, 21453 posts, 
From Slovenia, joined May 1999, 751 posts, 
From Hong Kong, joined Feb 2004, 15867 posts, 
Sponsor Message: 
Printer friendly format
