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Slats, How They Work?  
User currently offlineCarsim From Portugal, joined Nov 2001, 3 posts, RR: 0
Posted (12 years 6 months 2 weeks 4 days 14 hours ago) and read 4980 times:

Hello to all

I would like to know if someone could tell me how the slats work (is the flaps lever used to activate the slats?).
Is there any indication in the cockpit that the slats are activated, or they work together with the flaps?

Thank you and best regards

Simon

27 replies: All unread, showing first 25:
 
User currently offlineDavid B. From United States of America, joined Jun 2001, 3148 posts, RR: 5
Reply 1, posted (12 years 6 months 2 weeks 4 days 13 hours ago) and read 4842 times:


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Photo © Alexander Y.A. Kueh



Slants as you can see from the pic above, are basically inverted flaps. Instead of being at the trailing end of the wings, its on the front. Their jobs are the same as flaps; to expand the surface area of the wing so that air has a larger area to act on, thus increasing lift. On landing, they can be used, like flaps, to increase drag, so that the plane slows down without having to decrease engine power or applying speed brakes. Flaps and slants have a max operating speed. Deployment above that speed (indicated air speed) can cause structual damage.

Depending on the model of aircraft, slants can be controlled independent of flaps. Onc control for flaps and one for slants, both located next to each other. On newer planes, slants are incooperated with flaps. Im not sure but I think slants are 50% of flaps or somthing like that. (ex 40% flaps= 20% slants) Moving the flap lever also deploys slants. There might be an override but Im not sure. Smaller aircraft, older aircraft usually dont have slants, just flaps. There are also many types of flaps. From slimple single ones that just drop down to complex
tri-slot ones used on large jetliners.



Teenage-know-it-alls should be shot on sight
User currently offlineDavid B. From United States of America, joined Jun 2001, 3148 posts, RR: 5
Reply 2, posted (12 years 6 months 2 weeks 4 days 12 hours ago) and read 4810 times:

http://comm.db.erau.edu/esser/cont6.html
More on slants and flaps here.



Teenage-know-it-alls should be shot on sight
User currently offlineCdfmxtech From United States of America, joined Jul 2000, 1341 posts, RR: 26
Reply 3, posted (12 years 6 months 2 weeks 4 days 12 hours ago) and read 4810 times:

David B did OK, if he wouldnt have called them SLANTS. They aren't SLANTS!!!! They are called SLATS.

Only some airplanes can use flaps to aid in slowing down. The B727 is one of them. Its been said by some pilots that you could be haulin ass on the approach, and drop the flaps, and the thing would slow down dramatically. Now, ask a 737 driver the same thing, and you'll get a different answer.

The only plane that I know of with a mechanical link on the flap lever to control slats indepedent of teh flaps was the DC10. There may be others...but I dont know.


User currently offlinePikachu From Bhutan, joined Feb 2002, 89 posts, RR: 0
Reply 4, posted (12 years 6 months 2 weeks 4 days 12 hours ago) and read 4792 times:

The A330 has one lever referred to as a flap handle that controls both flaps and slats. What we call "FLAPS 1 " includes slat extension. The ECAM gives a good indication of all flight control surfaces.

User currently offlineDavid B. From United States of America, joined Jun 2001, 3148 posts, RR: 5
Reply 5, posted (12 years 6 months 2 weeks 4 days 12 hours ago) and read 4787 times:

Slants....Slats......personally I perfer slants...dont know why. Slants sounds better then Slats Big grin


Teenage-know-it-alls should be shot on sight
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 6, posted (12 years 6 months 2 weeks 4 days 11 hours ago) and read 4780 times:

David B,
hmm, perhaps. The slants are on the wongs and are extended with the flops as the plots pull the flop loafer in the crackpot.

Yay! I think we are reinventing ebonics here! Big grin Big grin

Cheers,
Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineDavid B. From United States of America, joined Jun 2001, 3148 posts, RR: 5
Reply 7, posted (12 years 6 months 2 weeks 4 days 11 hours ago) and read 4766 times:

Right here bro'

http://www.rinkworks.com/dialect/



Teenage-know-it-alls should be shot on sight
User currently offlineCarsim From Portugal, joined Nov 2001, 3 posts, RR: 0
Reply 8, posted (12 years 6 months 2 weeks 3 days 21 hours ago) and read 4713 times:

Hello to all

Thank you very much to all who reply to my question, it help me to understand how the slats work, sorry for the confusion about slats or slants.

Best regards and thank you again

Simon


User currently offline411A From United States of America, joined Nov 2001, 1826 posts, RR: 8
Reply 9, posted (12 years 6 months 2 weeks 3 days 6 hours ago) and read 4695 times:

Unfortunately Carsim..lots of mis-information here, including the explanation of the picture....they are leading edge kruger flaps, not slats.
Some here just....guess?


User currently offlineConcorde1518 From United States of America, joined May 2001, 746 posts, RR: 0
Reply 10, posted (12 years 6 months 2 weeks 3 days 1 hour ago) and read 4672 times:

FredT, ROFL! Great post!

User currently offlineAJ From Australia, joined Nov 1999, 2391 posts, RR: 24
Reply 11, posted (12 years 6 months 2 weeks 3 days ago) and read 4668 times:

That's true 411A, the 747 is fitted with leading edge flaps, not slats.
These are slats, extended on an A319. The slat forms a 'slot' between the slat and the wing, encouraging laminar airflow above the wing, as well as increasing the wing area, to enhance lift.

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Photo © Chris Waser



User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 12, posted (12 years 6 months 2 weeks 2 days 19 hours ago) and read 4652 times:

Hehe, there is certainly some confusion regarding the terminology in this area. Some people would call the Krüeger flaps leading edge flaps while other people call them slats or even slots. Other people use slats and slots respectively to make the distinction between leading edge devices with or without an airgap. And so on, ad nausea.  Smile

It's probably best to figure out what you're talking about, choose a terminology to use and live with the bother of having to spend a sentence explaining just what the f*ck yer on about. Big grin

The increased camber of the wing plays a bigger role than the increased area too, methinks.  Big grin Or, to make it bulletproof (not to mention confusing), slats/slots increase Clmax.

Cheers,
Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineAeroguy From United States of America, joined Aug 2001, 69 posts, RR: 0
Reply 13, posted (12 years 6 months 2 weeks 2 days 13 hours ago) and read 4643 times:

People tend to use the terminology pretty freely, probably because they're not sure what any of it really means. Unfortunately it confuses the issue for everyone.

Leading Edge Slot: a channel which permits air from under the wing to blow over the top surface of the wing - delays separation and stall


Leading Edge Flap: a hinged portion of the leading edge that droops down - increases camber and hence maximum lift


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Photo © Gerhard Plomitzer




Slat: a leading edge flap with a slot - provides increased camber, a slot, and increased wing area


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Photo © Chris Waser




Kruger (sometimes Krueger?) Flap: a panel that hinges downward from the lower surface of the wing when deployed - acts as an air dam to force air up over the top of the wing, lighter than slats, but has more drag


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User currently offlineCdfmxtech From United States of America, joined Jul 2000, 1341 posts, RR: 26
Reply 14, posted (12 years 6 months 2 weeks 2 days 13 hours ago) and read 4644 times:

Holy Sh*t, this is getting more complicated than it should be.

LE Flaps are hinged. They are a couple of different types, one being the Krueger. I believe the otehr is Camber.

LE Slats are not hinged. The are usually on tracks, and sort of slide down when actuated.

Some aircraft have both LE Flaps and Slats
The B737s have LE Flaps (Kruegers) inboard of the engines, and Slats outboard.

Some have 2 types of LE Flaps, such as the B747 Classic, which had Krueger and Cambers

Some have only slats, such as the B757/767.

All of the above increase wing area along with the TE Flaps.
---------------------------
A SLAT is not a SLOT, and a FLAp is not a SLAT. THEY ARE DIFFERENT!!!


User currently offlineMusang From United Kingdom, joined Apr 2001, 864 posts, RR: 7
Reply 15, posted (12 years 6 months 2 weeks 1 day 8 hours ago) and read 4601 times:

Further - is a slot not a fixed gap? like on certain DC-8 leading edges and the leading edge of the Cessna 177 horizontal stabiliser?

Regards - Musang


User currently offlinePrebennorholm From Denmark, joined Mar 2000, 6451 posts, RR: 54
Reply 16, posted (12 years 6 months 2 weeks 1 day 5 hours ago) and read 4601 times:

Read FredT's post. He knows it. Otherwise much of this thread is really "entertaining".

Just one thing is still missing. The slotted slats (as found on all busses and most newer Boeings) do increase Cl max by increasing profile camber.

But they actualy have a triple function They also increase airflow speed on the upper surface of the fixed part of the wing.

And finally, behind the slats they open for a different high lift profile, which on the other hand is inefficient at cruising speed.

All three functions increase Cl max.

On some early jet airliners, which totally lack leading edge high lift deviced, you will find a wing leading edge profile, which looks something like a compromise between the fixed wing profile behind an extended slat and the profile with retracted slat. Have a look at AJ's and Jetguy's A319 pix above.

Then take a close look at the wing root profile on for instance Tu-134 and B-707 and compare to modern airliners. Then you will see what I mean.

The B-707 is a very special example because it was modified into the somewhat lighter B-720. The 720 didn't need the high lift profile as much as the B-707, so one of the mods was a "leading edge glove" which changed the fixed profile into a more efficient one at high speed at the cost of a slightly reduced Cl max.

Regards, Preben Norholm



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineSunken_Lunken From United States of America, joined Jul 2001, 87 posts, RR: 0
Reply 17, posted (12 years 6 months 2 weeks 12 hours ago) and read 4570 times:

This is all starting to sound like a scene from the movie Airplane!

"OK Blatz, set flaps, check the slot on the slats,"

"Roger, Over".

"You got our clearance, Clerence?"

"What's our vector, Victor?"  Nuts


User currently offlineMr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 9
Reply 18, posted (12 years 6 months 2 weeks 11 hours ago) and read 4569 times:

Hi guys.

Great information...now that it's been clarified.

There's one very wicked bird out there that doesn't seem to need all these high lift devices along the leading edge....the Concorde.

From what I can tell from the photos below, The Concorde doesn't have either leading edge flaps or slats. It also appears to use very little, if any, trailing edge flaps during approach and landing, and it looks like it only has flight spoilers/speedbrakes...no ground spoilers.

Why is this?

I know this aircraft is unique with it's delta wing, but why dosen't it even have ground spoilers? Could it be because the wing is to thin for the equipment needed? I'm very curious.


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Chris  Smile



"Just a minute while I re-invent myself"
User currently offlinePrebennorholm From Denmark, joined Mar 2000, 6451 posts, RR: 54
Reply 19, posted (12 years 6 months 2 weeks 6 hours ago) and read 4550 times:

High lift devices on a wing changes the pitching moment considerably. Therefore a horizontal tail is needed to compensate for that.

Consequently tailless planes have no high lift devices.

Instead they usually have a very generous wing area, and a lighter wing loading - pounds of mass per square foot of wing area.

The Concorde is not alone to prove that. B-2A Spirit, XB-35/-49 experimental bomber, B-58A Hustler. And a lot of delta wing fighter planes.

Tailless planes like the Concorde also have no trailing edge flaps. If you see anything like that, then it is down elevator instead.

I never realized that it seem like the Concorde has no wing spoilers. They could not be used in flight because they would also change the pitching moment with no tail to compensate. Instead they would disturb or completely ruin the elevator control.

For landing the wing spoilers are not very efficient as brakes. Their main purpose on ordinary planes is to spoil the lift of the wing in order to give the wheels a more firm grip on the runway.

The Concorde lands with an extremely high nose attitude. As soon as it gets the nosewheel down, then it must have a very firm grip on the runway, so I don't think that it needs wing spoilers to kill the lift.

It might have had tail spoilers like the Fokker 100 or BAe 146 to be used during the landing approach.

But with the high nose attitude on approach the Concorde already produces an immensely high drag which must be countered by relatively high engine thrust. So I would assume that engines are used entirely for speed control.

Well, here were a lot a assumptions and semi qualified guesses - and a few facts. Does somebody have more facts about the Concorde and its flight control devices?

Regards, Preben Norholm



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 20, posted (12 years 6 months 1 week 6 days 17 hours ago) and read 4508 times:

A delta wing is a very peculiar thing aerodynamically. It keeps producing lift way after a normal wing would have stalled. What would have shed off as vortices at the wing tips on a normal wing shed off along the entire leading edge. This creates low-pressure vortices above the wing adding to the lift generated. It comes at a steep drag penalty however - that is why the AF Concorde which crashed ended up in trouble when the engines quit. They were on the backside of the power curve without the power or the altitude to get away from there.

As for not having spoilers, aerodynamical braking should be well enough once they have the mains down and retard the power levers. Compare it to the SAAB J35 Draken double delta fighter. They even added an extra gear under the exhaust to enable aero braking without worrying about tailstrikes.

Cheers,
Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineMusang From United Kingdom, joined Apr 2001, 864 posts, RR: 7
Reply 21, posted (12 years 6 months 1 week 6 days 16 hours ago) and read 4507 times:

The Mirage 4000 (first flown March '79) had full span leading edge devices and no tailplane, and I'm pretty sure some other Mirages did also. There is indeed a huge pitching moment associated with L/E extension, but the flaperons on a delta wing can counter this.

Regards - Musang


User currently offlineLZ-TLT From Germany, joined Apr 2001, 431 posts, RR: 0
Reply 22, posted (12 years 6 months 1 week 6 days 8 hours ago) and read 4491 times:

The Trident had two levers in the cockpit, operated independent from each other - one for the leading edge droops/kruger flaps, the second for the trailing edge flaps. Possibly a confusion between these two levers was the probable cause for the G-ARPI disaster.

User currently offlineA/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 4
Reply 23, posted (12 years 6 months 1 week 6 days 5 hours ago) and read 4476 times:

I believe the question still has not been awnsered correctly, Carsim would like to know how the slats work and what indications show Slat deployment.
Are you asking exactly how the systems function to deploy the slats, or are you asking of the aerodynamics and principle of operation, this has been jumbled and needs to be simplified. Carsim, do you have the information you requested?
regards
a/c


User currently offlineMr Spaceman From Canada, joined Mar 2001, 2787 posts, RR: 9
Reply 24, posted (12 years 6 months 1 week 6 days 5 hours ago) and read 4473 times:

Hi guys.

>Prebennorholm, FredT & Musang, Thanks for your replies regarding my questions about the Concorde's lack of high lift devices. Your info was great!

Even more amazing is that I actually understood all your answers and explanations. They made perfect sense to me. Cool!


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I suspect the Vulcan bomber's wings are very similar in design.


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Chris  Smile



"Just a minute while I re-invent myself"
25 Jsf119 : yeah but WHO"S ON FIRST???
26 Post contains links and images VapourTrails : Does somebody have more facts about the Concorde and its flight control devices? I'm going to say it again -- are there any Concorde pilots on A.net??
27 Post contains images Mr Spaceman : Hello VapourTrails. No sir, unfortunately I haven't seen any of those videos, but now I know they're out there. The links you posted are excellent, an
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