JAM747
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Difference Between Flaps And Slats?

Sat Apr 02, 2005 1:36 am

What is the difference between flaps and slats. Does it depend on the size or type of aircraft or do all aircrafts have both.
 
FredT
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RE: Difference Between Flaps And Slats?

Sat Apr 02, 2005 1:40 am

Do a search. The subject has come up in several incarnations here over the last few weeks.

The terminology is somewhat confused. My definition is that slats (and slots) are leading edge devices while flaps are trailing edge devices.

Cheers,
Fred
I thought I was doing good trying to avoid those airport hotels... and look at me now.
 
OPNLguy
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RE: Difference Between Flaps And Slats?

Sat Apr 02, 2005 1:55 am

Quoting FredT (Reply 1):
The terminology is somewhat confused. My definition is that slats (and slots) are leading edge devices while flaps are trailing edge devices.

It gets more confusing because Boeing uses leading edge Krueger flaps. MEL deferrals on L/E indication systems can get challenging sometimes because of the phonetic similarity between flaps (not deferrable) and slats (deferrable, with exceptions), and one has to annunciate very clearly.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
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Starlionblue
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RE: Difference Between Flaps And Slats?

Sat Apr 02, 2005 2:23 am

Slats are usually mounted on the leading edge. Slats extend the edge and sit like a glove on the edge.

Flaps are usually mounted on the trailing edge but can be mounted on the leading edge. They extend the edge but are not mounted like a glove. They either pivot only (simple and split flaps), extend and come down (complex and slotted flaps) or extend and camber (Krueger flaps). There are other types as well.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
411A
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RE: Difference Between Flaps And Slats?

Sat Apr 02, 2005 7:27 am

Not forgetting 'droops'...as on the first civil jet transport aircraft to achieve complete automatic approach/land certification...the HS.121 Trident.

A superb achievement, at the time.
Left the yanks FAR behind in automation.

And, I admire 'em greatly...even as a yank. Smile
 
UAcsOKC
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RE: Difference Between Flaps And Slats?

Sun Apr 03, 2005 9:54 pm

Quoting 411A (Reply 4):
superb achievement, at the time.
Left the yanks FAR behind in automation.

Also had problems with deep stall, associated with the droops. guess nobody's perfect....
I love the rumble of a 727 takeoff in the morning!
 
411A
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RE: Difference Between Flaps And Slats?

Mon Apr 04, 2005 6:24 am

Yes, nobodys perfect, UAcsOKC, especially the First Officer, who altho confused, nonetheless, retracted the droops far too soon.
Gotta watch these contrary co-pilots.  Wink
 
dubliftment
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RE: Difference Between Flaps And Slats?

Thu Jul 17, 2008 2:37 pm

as far as I know, "slats" is an abbrevation for "slotted flaps", meaning they have a nozzle like slot between the high-lift device and the wing. on the contrary, krueger flaps do not have this slot.
 
474218
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RE: Difference Between Flaps And Slats?

Thu Jul 17, 2008 9:08 pm



Quoting JAM747 (Thread starter):
What is the difference between flaps and slats. Does it depend on the size or type of aircraft or do all aircrafts have both.


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retracted slats

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extended slats

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flaps retracted

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flaps extended
 
avioniker
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RE: Difference Between Flaps And Slats?

Thu Jul 17, 2008 9:15 pm

Very simply put (and there are exceptions) Flaps are an extension of the wing and may or may not affect the aerodynamic chord length and angle.
Slats are more akin to an additional wing, forward of the wing, and act more to add lift than drag. Of course many aircraft have slats with more than one selectable position that may or may not be sealed to the wing in partial extension. So they act as flaps or slats depending on position.
Both flaps and slats act to lower the stall speed of the aircraft and provide enhanced low speed maneuverability.
I personally like the "slotted flap" explanation/definition. It makes sense and is easy to visualize.
 Smile
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
tdscanuck
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RE: Difference Between Flaps And Slats?

Fri Jul 18, 2008 1:37 am



Quoting Avioniker (Reply 9):
Slats are more akin to an additional wing, forward of the wing, and act more to add lift than drag.

Slats do very little to add lift directly. Their main contribution is to allow an increases angle of attack prior to stall. It's the increased AoA, not the slat itself, that generates the extra lift.

Tom.
 
WPIAeroGuy
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RE: Difference Between Flaps And Slats?

Fri Jul 18, 2008 2:29 am

Flaps, slats, kreuger flaps, etc. all work by increasing the camber of the wing, which allows for a higher AoA and increased drag. Some flaps also increase the chord.

Slats have a gap between the slat and the LE, airflow through the slot is redirected over the top surface of the wing, increasing airflow over the wing which increases lift. Slotted flaps work on the same princicple, the slots in the flaps allows for the airflow to remain stay attached through higher angles of attack, ergo creating more lift.

I know the Bf-109 and F-86 had leading edge devices that responded automatically to prevent loss of lift in high AoA situations. I believe the F-22 has similar devices though I may be very wrong.
-WPIAeroGuy
 
wingscrubber
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RE: Difference Between Flaps And Slats?

Fri Jul 18, 2008 2:41 am

JAM747, Flaps are trailing edge lift aids/drag inducers, slats are leading edge lift aids/drag inducers. Flaps are on most anything that flies with some exceptions, but slats are generally only prevalent on bigger aircraft, but there's exceptions to that too.

This is my favourite wing design ever - achieves fantastic STOL. Big fat camber with fixed slat and flaperon. Brilliant.
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Zuluaviator994
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RE: Difference Between Flaps And Slats?

Mon Jul 21, 2008 12:41 am



Quoting Wingscrubber (Reply 12):
Wingscrubber

What plane is that?
If Speed is life, Altitude is life insurance. No one has ever collided with the sky.
 
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Starlionblue
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RE: Difference Between Flaps And Slats?

Mon Jul 21, 2008 12:46 am



Quoting Wingscrubber (Reply 12):
JAM747, Flaps are trailing edge lift aids/drag inducers, slats are leading edge lift aids/drag inducers.

I disagree. There are plenty of flaps on leading edges, for example on the 747 and the 737.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
boeing767mech
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RE: Difference Between Flaps And Slats?

Mon Jul 21, 2008 1:13 am



Quoting Starlionblue (Reply 14):
There are plenty of flaps on leading edges, for example on the 747 and the 737.

Don't forget the CV-990A

David
Never under-estimate the predictably of stupidty
 
wingscrubber
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RE: Difference Between Flaps And Slats?

Mon Jul 21, 2008 4:46 am

Thats the Zenith CH701/801 wing. Sorry should have said what it was...
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Pihero
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RE: Difference Between Flaps And Slats?

Mon Jul 21, 2008 10:36 am



Quoting Wingscrubber (Reply 12):
This is my favourite wing design ever - achieves fantastic STOL. Big fat camber with fixed slat and flaperon. Brilliant.

....and really nothing new since the Fieseler Storch .

From Wiki :
" Penned by chief designer Reinhold Mews and technical director Erich Bachen, Fieseler's entry was the most advanced in terms of STOL performance, by far. A fixed slat ran along the entire leading edge of the long wings, while the trailing edge, inspired by earlier 1930s Junkers aircraft wing control surface designs, including the ailerons, was a hinged and slotted flap. The wings could be folded back along the fuselage, allowing it to be carried on a trailer or even towed slowly behind a vehicle. "...
"The first Fi 156 V1 prototype flew in the spring of 1936. It was powered by a 180 kW (240 hp) inverted-vee Argus As 10C V8 engine, which gave the plane a top speed of only 175 km/h (109 mph), enabling the Storch to fly as slow as 50 km/h (32 mph), take off into a light wind in less than 45 m (150 ft), and land in 18 m (60 ft). "
Contrail designer
 
MD-90
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RE: Difference Between Flaps And Slats?

Mon Jul 21, 2008 11:33 am



Quoting Wingscrubber (Reply 12):
This is my favourite wing design ever - achieves fantastic STOL. Big fat camber with fixed slat and flaperon. Brilliant.

Never going to win any races, however.
 
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Starlionblue
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RE: Difference Between Flaps And Slats?

Mon Jul 21, 2008 2:37 pm



Quoting MD-90 (Reply 18):
Never going to win any races, however.

If they had a STOL competition.  Wink
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Nicoeddf
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RE: Difference Between Flaps And Slats?

Mon Jul 21, 2008 5:22 pm



Quoting MD-90 (Reply 18):
Never going to win any races, however.

And speed is not always your friend...lift is...in the air...and in the bed... Big grin
 
Tristarsteve
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RE: Difference Between Flaps And Slats?

Mon Jul 21, 2008 8:07 pm



Quoting 411A (Reply 4):
Not forgetting 'droops'...as on the first civil jet transport aircraft to achieve complete automatic approach/land certification...the HS.121 Trident.



Quoting Tdscanuck (Reply 10):
Slats do very little to add lift directly

My recollection is that the droop leading edge on the Trident 1 increased the lift by 40pc. When the pilot retracted the droops the plane stopped flying.
The original Trident design had two levers, a droop lever and a flap lever. After this accident they were interconnected with a baulk system, and from that day (1968) all aircraft had a single lever.
Later Tridents had slats instead.
 
MD-90
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RE: Difference Between Flaps And Slats?

Tue Jul 22, 2008 2:40 am



Quoting NicoEDDF (Reply 20):
And speed is not always your friend...lift is...in the air...and in the bed... Big grin

haha good one. I hear that the Zenith 701/801 series fly well. They certainly seem to be popular with homebuilders.

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