Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
soaringadi
Topic Author
Posts: 452
Joined: Fri Apr 30, 2004 4:56 pm

Spoilers/speed Brakes Question?

Mon May 31, 2004 2:38 pm

I know this sounds dumb.... but since I have never noticed it, neither know about it I'm gonna ask this question.....

Do the pilots ever use the spoilers during the descent, or on final approach ???

hope u guys can help me....

thanx  Smile
If it ain't Boeing, I'm not going !
 
modesto2
Posts: 2730
Joined: Sun Jul 16, 2000 3:44 am

RE: Spoilers/speed Brakes Question?

Mon May 31, 2004 3:51 pm

Spoilers are often used on the descent to reduce speed and/or increase vertical speed. I have never seen pilots use them on final approach. At this phase of flight, they shouldn't be necessay. The aircraft should be established on the approach and the gear and flaps should create enough drag. Significant speed reduction can be accomplished with thrust reduction.
 
dl757md
Posts: 1483
Joined: Mon May 24, 2004 9:32 am

RE: Spoilers/speed Brakes Question?

Mon May 31, 2004 4:40 pm

There are several threads already in tech ops about spoilers.
I agree with Modesto2 about spoiler usage by the pilots. You will see the spoilers work in concert with the ailerons during final approach on most commercial planes. This is automatic and is not initiated by the pilots as a spoiler command but rather as a roll command through the control column or sidestick.
757 Most beautiful airliner in the sky!
 
QantasA332
Posts: 1473
Joined: Sat Dec 13, 2003 5:47 pm

RE: Spoilers/speed Brakes Question?

Mon May 31, 2004 6:56 pm

Adequate speed reduction isn't the only consideration underlying why spoilers aren't usually used (for their both-up speedbrake function) on finals/short finals; stall speed also comes into play. Put simply, spoilers reduce the maximum coefficient of lift (Clmax) of the wing, directly increasing stall speed (Vs). It's usually desireable to have the lowest possible Vs when landing (flaps obviously help with this by increasing the wing's Clmax), meaning spoilers aren't deployed (i.e. they aren't both deployed for speedbrake 'mode', as I said before). In addition to increasing Vs, spoilers obviously slow the aircraft. This can lead to another possible problem as Vs goes up and the aircraft's speed goes down, with the chance of the two passing each other if you're not careful.

Having said all that, I suggest you check out the thread(s) DI757md mentioned, where you'll find that I just repeated everything I said before Embarrassment, and some other good info as well.

Cheers,
QantasA332

[Edited 2004-05-31 12:02:10]
 
CX Flyboy
Posts: 6148
Joined: Sun Dec 26, 1999 6:10 pm

RE: Spoilers/speed Brakes Question?

Mon May 31, 2004 11:20 pm

There are no restrictions on using the spoilers in the 777 at any stage of the flight, and that includes flaps 30 and gear down. As mentionned, this would be a very unusual time to use it, but sometimes, spoilers are neccessary even on approach. ATC can sometimes ask for a higher speed to be maintained than we would normally choose, and in order to lower the next stage of flap, the spoilers might have to be used.

Some airports have high crossing heights on approach and also high ATC speed requirements. Different aircraft have different operating techniques and in the 747-400 we used to put gear and flaps out early and use the drag to slow us down, but in the 777 we use the spoilers to slow us down to a more appropriate speed before configuring.
 
User avatar
barney captain
Posts: 2364
Joined: Tue Nov 06, 2001 5:47 pm

RE: Spoilers/speed Brakes Question?

Tue Jun 08, 2004 4:50 pm

Easy Cx flyboy. That is the very technique we have used at SWA for over 30 years only to discover flap spindle failures on approach that, according to the Boeing test pilots that recreated them were, "unrecoverable". Fortunately, our outcome was better, but please, believe it or not, the Boeing guys never test the wing or it's components for a flap/speed brake configuration. They indicate that it's not a condition one would normally encounter. You and I know better....
Southeast Of Disorder
 
User avatar
Aaron747
Posts: 12692
Joined: Thu Aug 07, 2003 2:07 am

RE: Spoilers/speed Brakes Question?

Wed Jun 09, 2004 5:12 am

That's astonishing considering spoiler panels and flaps are both wing structures that are exposed to specific and pronounced stresses as aerodynamic components - I'd have just assumed that Boeing would have tested them in all configurations. Frankly, that's rather surprising.
If you need someone to blame / throw a rock in the air / you'll hit someone guilty
 
Rick767
Posts: 2613
Joined: Sun Jan 30, 2000 8:11 pm

RE: Spoilers/speed Brakes Question?

Wed Jun 09, 2004 7:15 am

"They indicate that it's not a condition one would normally encounter."

Not my experience of approaching 5 years on the Boeings... flaps and spoiler together is a common requirement (especially so on the 757) to get it to "go down and slow down". My previous airline for example preached speedbrake usage on the 757/767 (up to Flap 20 settings) as "whatever it takes" to get it back on the profile.

Have done it (or had to do it!) countless times...
I used to love the smell of Jet-A in the morning...
 
nudelhirsch
Posts: 1371
Joined: Sun Oct 12, 2003 6:20 am

RE: Spoilers/speed Brakes Question?

Wed Jun 09, 2004 5:36 pm

I have seen that before, but it is getting noisy, and also pilots here said it creates vibrations, so some pilots generally try to avoid using them, only if they are descending to rapidly and gain too much speed they are used.
Putana da Seatbeltz!
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: Spoilers/speed Brakes Question?

Wed Jun 09, 2004 6:17 pm

Repeated for those that did not notice my previous comments about older jet aircraft...'What's the big deal about jets?'

Newer types are a pleasure to fly, very responsive.
Older types however, are a different kettle of fish altogether (speaking B707-321, JT4 powered here...).
Take for example...descent.
At 110 miles, close the throttles.
Duh, that was not a good idea, the Flight Engineer is having a fit because he cannot maintain pressurisation...as he grabs the inboard throttles and pushes them smartly up, to ensure turbocompressor spool-up.
So, down we go...now at thirty miles and still at 15,000, hmmm, lets grab a handful of spoilers. Ohhh, that was not a good idea, now the aircraft is shaking so much that you cannot read the instruments.
A better idea would be to split the spoilers (inboards OFF), ahhh, that works better, except now both you and the co-pilot have to push smartly forward on the column, to keep the nose from pitching up (way UP)...opps, started the stab trim too late, now the jackscrew is stalled.
Now, slightly low on the glide, a fistfull of throttles (why does it take so LONG for spool-up, opps, forgot, non-fan engines).
Gusty winds on final, no problem, the yaw damper will take care of this...NOT.
It had to be switched OFF at 1000agl, leaving you to arm wrestle the pig to the ground.

The handling qualities of the early heavy jet transports was very poor...new guys, on modern types, have it EASY.
 
MD11Engineer
Posts: 13899
Joined: Sun Oct 26, 2003 5:25 am

RE: Spoilers/speed Brakes Question?

Thu Jun 10, 2004 1:09 am

The MD-11 has an interlock, which prevents the use of speedbrakes after flaps have been deployed. Theoreticaly it is possible to set the flaps AFTER the speedbrakes are up, but acc. to one of our pilots it is not advisable because the plane turns into something like a brick or a piano.

Jan
Je Suis Charlie et je suis Ahmet aussi
 
User avatar
barney captain
Posts: 2364
Joined: Tue Nov 06, 2001 5:47 pm

RE: Spoilers/speed Brakes Question?

Mon Jun 14, 2004 6:23 am

Rick;

""They indicate that it's not a condition one would normally encounter."

Not my experience of approaching 5 years on the Boeings... flaps and spoiler together is a common requirement (especially so on the 757) to get it to "go down and slow down". My previous airline for example preached speedbrake usage on the 757/767 (up to Flap 20 settings) as "whatever it takes" to get it back on the profile.

Have done it (or had to do it!) countless times... "


Exactly my friend.....that's why I included this after my statement....

"You and I know better...."  Smile



Southeast Of Disorder
 
tangoecho
Posts: 123
Joined: Thu May 13, 2004 3:10 am

RE: Spoilers/speed Brakes Question?

Tue Jun 15, 2004 5:58 am

On the descent in a RyanAir 737-200 full deployment of the spoiler/speedbrakes was used for a good 10 mins, which I thought was a bit strange.  Wow!
Contact Aberdeen tower on 118.10 G'day.
 
nudelhirsch
Posts: 1371
Joined: Sun Oct 12, 2003 6:20 am

RE: Spoilers/speed Brakes Question?

Tue Jun 15, 2004 4:46 pm

Probably depends on thick air traffic apts...

Not seen it in HAM, STR, ARN, CPH, BNA, and so, but F R A ....wow, on a LH 744...

Think, if steep descend and still slowing down is necessesary then better go for it...
Putana da Seatbeltz!
 
Corsair2
Posts: 243
Joined: Thu Jan 25, 2001 11:02 pm

RE: Spoilers/speed Brakes Question?

Tue Jun 22, 2004 11:21 pm

Mechanical interlocks on the 717 prevent the speedbrake handles movement after Flaps 8.

On a ValuJet DC-9 flight back around 1996, the spoilers deployed prior to landing due to a series of malfunctions with the older protection system.
"We have clearance Clarence. Roger, Roger. What's our vector Victor?"

Who is online

Users browsing this forum: ARNPEK and 17 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos