How did the automatic slats on Bf109 worked?

[miko2d]

 They opened automatically at the high andle of attack and or at low speed. They apparently were independent and could open assymetrically (one wing and not the other).

 Anybody know how they were operated (air, hidraulic, mechanical) and where did they take their input - sensors (what kind?), computer, accelerometer, telepathy, etc.?

 With so many dedicated LW craisies... er, fans around, somebody should know enough to shed the light on the details of the slats operation. May be HTC will even use that info in the future implementation (add slats to 109s but disable their rudder trim - he, he...).

 Why were they not used more widely, and what other planes had them?

 While you are at it, please tell me the difference bewteen regular flaps and the combat "butterfly" flaps used on the some of the japanese planes - design, shape, etc.

 miko--

[Flacke]

Miko, the leading edge slats were held extended by a light spring action, and it is only air loads that retract them against the wing. At high angles of attack [at any airspeed, its angle of attack that counts] the slats extend and increase the camber of the wing [airfoil] thereby increasing the lift on that wing, very usefull in tight turns or on slow landing approachs[high angle of attack] also on takeoff, when added lift is a good thing. The British seemed to like slats more than other nations at the time. On the downside, slats require adjustments, are prone to damage, add dreaded weight, and can be deadly if they operate incorrectly or stick in the wrong position on one wing only. As wing designs improved, the downside of slats made them unecessary and not worth the bother. Keep Flyin!

[Jekyll]

RE:  Standard-v- Butterfly flaps.

Standard Flaps - take a look at the P51.  The flap is merely a control surface which angles down when activated, changing the camber of the airfoil but not changing the overall wing surface area.

Butterfly Flaps - now imagine a flap which is partially hidden within the wing itself.  When the flaps are actuated, they first extend backwards from the wing (increasing overall wing area) and then angle downward (changing the camber of the airfoil.  Increasing the effective wing area of course decreases the effective wing loading, enabling the aircraft to be more maneuverable at low airspeeds.

Next time you're in a modern jet airliner, take a look at the flaps when they deploy.  You'll see that the flaps first extend backwards out of the wing, and then droop downwards.  A modern version of the butterfly flap.

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C.O. Phoenix Squadron
www.users.bigpond.com/afinlayson/index.htm
'feel the heat .......'

[Sharky]

Jekyll,

I think that those type of flaps (butterfly)are refered to as "Fowler" type flaps.  I think the only WWII warbirds that used them were the P-38s.  At least as far as US iron is considered, I don't recall any of the other nations using them.  They are very effective but complicated and heavy.

Sharky

[funked]

Yep you are describing Fowler flaps.

BTW the Me 262 has the same type of slat system as the Me 109.  I verified this once manually.  I pushed the left slat up and it sprang right back.  

[funked]

Flacke:

"As wing designs improved, the downside of slats made them unecessary and not worth the bother."

Ummm NOPE!  

Just about every fighter plane flying today has slats, and so does just about every airliner.  These days the slats are mechanically driven by an electrical or hydraulic actuator.  On airliners they are linked to the flaps (same handle does flaps and slats).  On fighters they are usually controlled automatically by the flight control system.

[Sink]

Japanese fighters with butterfly flaps

Ki43
Ki44
Ki84

Also I think the N1K1-J and N1K2-J had automatic versions of these flaps. I am certain they were automatic but not so much they were butterfly flaps.

[Sharky]

Sink,

Are you sure?  I thought all the Japanesse planes used the simple flap like the P-51 or the split flap design like the P-40.

Sharky

[jocko-]

Anal-retentive correction:  Jetliners do not use Fowler flaps, they use Slotted (sometimes Double or Triple Slotted)Flaps, where the air can flow over and through the wing's trailing edge to maintain a smooth (laminar) flow.  Fowler flaps do not have a gap between the flap and the wing.  P-38s had Fowler flaps, a modern example is the Dash-8 Turbo-prop. (A fine Canadian product  )

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Cheers!

jocko-

[bod]

Automatic slats were very much used. I visited the airplane museum near Prague a month ago, and manually extended the slats of a La-8 ? or 7 ? I dont remember. There where no springs. Basically the stagnation point changes so that it is pushed forward (or sucked forward) at high AOA.

Even the F-86 had automatic slats.


Bod

[eagl]

Funked and others...

Remember after the F-86, leading edge slats kinda took a leave of absence until the F-16.  Granted, some of the delta-winged fighters had drooped leading edges and the F-15 has a rather dramatically drooped leading edge shape to the wing, the leading edge slat disappeared from USAF fighters until the concept of the mission adaptable wing reappeared with the F-111.  The F-16 and probably all future USAF fighters will use drooping leading edges, but not true leading edge slats.  The EA-6 and some other naval fighters continued to use leading edge slats through those interim years, but that is primarily because of the very low speeds required for carrier landings.

I think that some F-4 phantom variants used leading edge extensions and slats, and there was one variant with a slat on the elevator that also used engine bleed air for boundary layer control (increasing pitch authority at all AOA's) but the whole-wing leading edge slat at least temporarily disappeared in favor of a single simpler wing design or a relatively simple leading edge drooping mechanism.


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eagl <squealing Pigs> BYA
Oink Oink To War!!!

[eazydweeb]

Hi there,

btw: There is a series of SOCATA MORANE sportplanes, very common here in Europe, that uses these slats. The slats have no spring or  lever activation, they're "sucked" out at a specific AOA. Never flew it myself but often tried the mechanism in our hangar. The pilot makes shure slats are extended during preflight check.
If I knew how to post a picture...
 

Cheers

eazydweeb
 

[funked]

Eagl, F-15's don't count because they aren't fighter planes.

<g,d,r>  

And I'm defining slats to be devices which vary the incidence of all or part of the leading edge of the wing.  I'm including full-span or partial-span configurations.

Admittedly, there are no slats on F-101, F-102/106, F-104, F-105, F-14, F-5, Harrier, or F-117.

But F-100, F-4, A-7, A-10, F-111, F-16 and F-18 use slats.
 
Looking abroad, Mirage, Tornado, Mig-29, Su-17, Mig-23/27, Su-24, Su-25, and Su-27 all use slats.

And new fighters like the F-22, Rafale, Gripen, Eurofighter all have slats.

So I think my statement, "Just about every fighter plane flying today has slats" is pretty much true.  

Anyways we need to have slats and flaps on new planes so that I have work to do!  Also I think we need more weapon bay door and pitch trim systems!

[funked]

"a relatively simple leading edge drooping mechanism."

Doh I should RTFM.  I'm calling those slats.  

[Sink]

Sharky,

The butterfly flap was a development of Nakajima Aircraft Co. and was designed  during the development of the Ki44 to meet a requirement to decrease turn radius. A button on the stick extended the flap during combat and another push would retract it. It was so successful the butterfly flap was installed in the Ki43 which was in preproduction. All Nakajima fighters designed after the Ki44 incorporated the butterfly flap.