trichos
Posts: 22
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Why Don't Some Spoiler Panels Line Up?

Sat Jun 23, 2007 2:00 am

Just a question of curiosity.
I've noticed that on landing the spoiler panels on some aircraft don't seem to go up the same amount (737's?). In other aircraft they all seem to go up the same amount and line up. Is this a common to some aircraft models? Is it just sign or wear or loss of calibration? Is it a design feature, as there may be less room for the mechanism in some wing areas?

Example. http://www.airliners.net/open.file?i...19&prev_id=1167724&next_id=1166095
In some videos from the window view it seems to be a more random line up.

Thanks
 
Tristarsteve
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RE: Why Don't Some Spoiler Panels Line Up?

Sat Jun 23, 2007 3:25 am

It is a design feature, and its pretty common on most airliners.
 
474218
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RE: Why Don't Some Spoiler Panels Line Up?

Sat Jun 23, 2007 10:01 am

There are limits to the amount the spoiler panels should deploy (both minimum and maximum). As long as they are within the limits no re-rigging is required, so some may not appear to be deployed as far as others it is normal.
 
roseflyer
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RE: Why Don't Some Spoiler Panels Line Up?

Sat Jun 23, 2007 4:41 pm

One thing to note is that there are two types of spoilers. There are inflight spoilers and ground spoilers.

The spoilers are interesting because they take the most hydraulic fluid of anything on the plane normally to run since they experience high forces when in flight.

As far as the placement goes, they are located closely in regards to where the flaps deploy. I'm not an aero guy, so I can't say why they deploy to different angles, but I guess that it has something to do with a large flat plate would have some weird vorticies coming off of it that probably should be avoided.
If you have never designed an airplane part before, let the real designers do the work!
 
411A
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RE: Why Don't Some Spoiler Panels Line Up?

Sun Jun 24, 2007 12:03 am

Quoting RoseFlyer (Reply 3):
The spoilers are interesting because they take the most hydraulic fluid of anything on the plane normally to run since they experience high forces when in flight.

Nonsense.

Spoilers use very little hydraulic fluid displacement for their operation...landing gear and flaps/slats use far more.

Quoting RoseFlyer (Reply 3):
I'm not an aero guy....

I would imagine so, and it shows.
 
roseflyer
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RE: Why Don't Some Spoiler Panels Line Up?

Sun Jun 24, 2007 1:08 am

Quoting 411A (Reply 4):
Quoting RoseFlyer (Reply 3):
The spoilers are interesting because they take the most hydraulic fluid of anything on the plane normally to run since they experience high forces when in flight.

Nonsense.

Spoilers use very little hydraulic fluid displacement for their operation...landing gear and flaps/slats use far more.

You are right that it makes no sense now. I might be typically off kilter here, but from what I understand, they are a high demand system and from my experience they use the most fluid of any system on the ground. They take more fluid to operate than the thrust reversers, elevators, rudders or ailerons. Unlike the landing gear per se, the spoilers require a constant fluid pressure to be maintained in the up position. Landing gear takes a lot of force and fluid to retract, but that's not a continuous operation. Each spoiler actuator (2 per spoiler) is smaller than the landing gear actuator, but collectively with full spoilers up, the actuators are a high demand system.

[Edited 2007-06-23 18:35:47]
If you have never designed an airplane part before, let the real designers do the work!
 
Tristarsteve
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RE: Why Don't Some Spoiler Panels Line Up?

Sun Jun 24, 2007 2:26 am

Quoting RoseFlyer (Reply 5):
You are right that it makes no sense now. I might be typically off kilter here, but from what I understand, they are a high demand system and from my experience they use the most fluid of any system on the ground. They take more fluid to operate than the thrust reversers, elevators, rudders or ailerons. Unlike the landing gear per se, the spoilers require a constant fluid pressure to be maintained in the up position. Landing gear takes a lot of force and fluid to retract, but that's not a continuous operation. Each spoiler actuator (2 per spoiler) is smaller than the landing gear actuator, but collectively with full spoilers up, the actuators are a high demand system.

Lets take the B737 as your picture shows it.
The B737-200 has 8 spoilers, the B747-400 has 10.
They work in exactly the same way. They are numbered (on-400) 0 to 9 left wing tip to right wing tip.
Spoilers 0 1 4 5 8 9 are ground spoilers Spoilers 2 3 6 7 are ground and flight spoilers.
The ground spoilers extend to 60 deg, the flight spoilers to 40 deg.
The ground spoilers are up or down. There is no intermediate posn, and the actuators, one per spoiler except 4 and 5 which have 2 each, lock in the fully extended, and fully retracted posn.
The flight spoilers are fully variable and are used as speedbrakes and roll assist as well as ground spoilers. If there is an input from the control wheel, the flight spoilers may retract during landing as the ailerons move.
The B737NG has a nearly identical system. I.e. it is fully mechanically controlled and still has that wonderfull piece of engineering in the wheel well, the spoiler mixer.
There is no special hydraulic supply for the ground spoilers, unlike the B777 which runs up the ADP to supply more hyd flow on landing.
The spoiler lever in the flight deck can always be selected, but on landing it is usually driven to the deploy position by an electric motor automatically, basically on wheel spin up. If the right main gear oleo is depressed enough a teleflex cable operates the ground spoiler selector and they will go up as well.
On new aircraft from B757 onwards spoilers are all electronically controlled, and the displacement is not so even.
For some reason Boeing stayed with mechanical control on the NG, must have been cheaper than changing to computor control.
 
redflyer
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RE: Why Don't Some Spoiler Panels Line Up?

Sun Jun 24, 2007 2:42 am

Quoting TristarSteve (Reply 6):
They work in exactly the same way. They are numbered (on-400) 0 to 9 left wing tip to right wing tip.

Just curious, but why would a spoiler (or any other device) be numbered "0"? I've only seen "0" applied as a device number on computer equipment (e.g., hard disk 0, 1, etc.). They don't number the engines 0, 1, 2, 3, so why number another piece of mechanical device as such?
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HAWK21M
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RE: Why Don't Some Spoiler Panels Line Up?

Sun Jun 24, 2007 2:46 am

The Inbd normally Rise less in Air & more on Grd.A pair one on each side are only Grd Speed brakes on the B752.On the B732 The Inbd Spoilers are only Grd Speed brakes & deflect the most.

regds
MEL
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Tristarsteve
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RE: Why Don't Some Spoiler Panels Line Up?

Sun Jun 24, 2007 3:00 am

Quoting RedFlyer (Reply 7):
Just curious, but why would a spoiler (or any other device) be numbered "0"? I've only seen "0" applied as a device number on computer equipment (e.g., hard disk 0, 1, etc.). They don't number the engines 0, 1, 2, 3, so why number another piece of mechanical device as such?

because the -200 had 8 spoilers, 1 to 8, and the -400 added one at each end.
 
redflyer
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RE: Why Don't Some Spoiler Panels Line Up?

Sun Jun 24, 2007 4:59 am

Quoting TristarSteve (Reply 9):
because the -200 had 8 spoilers, 1 to 8, and the -400 added one at each end.

Ah, I knew you'd come up with a good explanation. Thanks!  Smile
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jetmech
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RE: Why Don't Some Spoiler Panels Line Up?

Sun Jun 24, 2007 12:26 pm

Quoting RoseFlyer (Reply 3):
The spoilers are interesting because they take the most hydraulic fluid of anything on the plane normally to run since they experience high forces when in flight.

Don't forget that the spoiler system of the B744 is powered by three of the four hydraulic systems. If you situate yourself behind a 744, the spoilers, IIRC are powered by systems 3,2,2,3,4,4,4,4,3,2,2,3 when scanning across from the left hand wing to the right hand wing. Collectively, the amount of hydraulic fluid demand may be appreciable, but the load on any one hydraulic system is very reasonable.

Quoting TristarSteve (Reply 6):
B747-400 has 10.

Does the 744 have 12 spoiler panels in total  Confused .


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Tristarsteve
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RE: Why Don't Some Spoiler Panels Line Up?

Mon Jun 25, 2007 1:15 am

Quoting JetMech (Reply 11):
Quoting TristarSteve (Reply 6):
B747-400 has 10.

Does the 744 have 12 spoiler panels in total .

Sorry mistype, I was talking about B737-400.
 
troubleshooter
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RE: Why Don't Some Spoiler Panels Line Up?

Wed Jun 27, 2007 6:03 am

On the B737NG the flight spoiler (2,3,4,5,8,9,10,11) have different extensions to put equal loads on the wings during extension. Spoiler 2,3,10,11 deploy to max. 33° and spoiler 4,5,8,9 deploy to max. 38°. Flight spoiler reach their maximum extension when the control wheel is turned 70° or when the speed brake lever is in "UP" position.

Ground spoiler (1,6,7,12) are an independent system and deploy to max. 52° (6,7) and 60° (1,12).
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