highflyer9790
Posts: 1189
Joined: Thu Jul 07, 2005 1:21 am

Spoiler Deployment

Sun Apr 01, 2007 12:14 am

Hey everyone-

Im just wondering about the connection from the spoiler handle in the cockpit to the actual spoilers. On a boeing aircraft, the spoilers have some kind of a mechanical connection to the handle where as airbus is completely electrical? if thats the case, then if a pilot moves the handle to the full flight detent position very fast in a boeing, will the spoilers go up just as fast? could the be damaging to the spoilers? With airbus, ive noticed the deployment seems a lot smoother than boeing's- becasue they always come up at the same speed regardless of the speed of the handle? (not talking about auto deployment on landing- just about the manual deployment on descent)

thanks a bunch!

highflyer
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Valkyrie01
Posts: 52
Joined: Fri Mar 09, 2007 2:12 pm

RE: Spoiler Deployment

Sun Apr 01, 2007 7:36 am

Quoting HighFlyer9790 (Thread starter):
Im just wondering about the connection from the spoiler handle in the cockpit to the actual spoilers. On a boeing aircraft, the spoilers have some kind of a mechanical connection to the handle where as airbus is completely electrical?

I hope this does not turn into an A vs B, personally i get tired of those.
As for A/C you did not specify which ones. 757/767 spoilers are electonically controlled and hydraulic operated. The 777 operates the same way and they called it FBW. As far as mechanical control to the speed brake lever/spoiler handle there is a control rod that is attach to the speed brake mechanism which includes lvdt(757/767) rvdt(777) etc etc.As for AB i am sure there as to be a control rod or some other mechanical connection on the speed brake lever,but i could be wrong.

Quoting HighFlyer9790 (Thread starter):
if thats the case, then if a pilot moves the handle to the full flight detent position very fast in a boeing, will the spoilers go up just as fast? could the be damaging to the spoilers?

The spoilers increase drag and decrease the amount of lift the wing supply,yeah the spoilers will go up just as fast on the A/C i mention above.

Quoting HighFlyer9790 (Thread starter):
With airbus, ive noticed the deployment seems a lot smoother than boeing's- becasue they always come up at the same speed regardless of the speed of the handle?

When i ops chk spoilers they seem to deploy at the same speed unless an actuator is not working properly
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411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: Spoiler Deployment

Mon Apr 02, 2007 1:28 am

L1011.

Pull the spoiler handle up rapidly, the spoilers extend radidly.

Pull the spoiler handle up slowly, spoilers extend slowly.

No specific speed limit for spoiler use on this type, and indeed little if any pitch change is noted with spoiler use.
 
474218
Posts: 4510
Joined: Mon Oct 10, 2005 12:27 pm

RE: Spoiler Deployment

Mon Apr 02, 2007 4:58 am

Quoting 411A (Reply 2):
L1011.

Pull the spoiler handle up rapidly, the spoilers extend radidly.

Pull the spoiler handle up slowly, spoilers extend slowly.

No specific speed limit for spoiler use on this type, and indeed little if any pitch change is noted with spoiler use.

411A,

The spoilers on the L-1011 will actually blow down, not all the way down but to a specific point for each individual spoiler panel, if the the spoilers are deployed at too high a speed.
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: Spoiler Deployment

Mon Apr 02, 2007 7:41 am

Indeed so, 474218...quite a nice design, unlike some early Boeing designs that I have flown...especially in the no pitch change arena.
Lockheed did it right.
 
User avatar
Jetlagged
Posts: 2562
Joined: Sun Jan 23, 2005 3:00 pm

RE: Spoiler Deployment

Mon Apr 02, 2007 9:51 am

Quoting HighFlyer9790 (Thread starter):
On a boeing aircraft, the spoilers have some kind of a mechanical connection to the handle where as airbus is completely electrical? if thats the case, then if a pilot moves the handle to the full flight detent position very fast in a boeing, will the spoilers go up just as fast? could the be damaging to the spoilers?

In older Boeings it's a mechanical connection to a speedbrake/spoiler mixer system to a hydraulic actuator on each panel. This will be rate limited to an extent, so even if you snap the speedbrake lever back quickly the spoilers can only move at their maximum rate, which can be modified at the design stage with flow restrictors. As for damaging them, all spoiler systems I know of are designed to blowdown so at high speeds they will deflect less. In "mechanical" systems this is usually achieved with pressure relief valves in the hydraulics. Clearly at higher speeds the spoiler rate will be reduced as well as the maximum deflection.

With FBW aircraft things are more complex. For example, on the A320 spoiler rate is affected by whether the autopilot is engaged or not. Maximum spoiler deflection is also limited if the autopilot is engaged. Even so, if you move the Airbus speedbrake lever slowly, the spoilers will only deflect slowly. The pilot still has the opportunity to use finesse at the controls.
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