Leading edge wing slats

[taffy2jeffmorgan]

Hi, I have a good idea of the workings of leading edge slats [ increase of attack angle presented to air flow ] and I notice that only some of both German and Russian aircraft had them fitted.

 

Where any Western allied aircraft fitted with this application or is it a cast of different or even better wing design ? what ever the reason, its a very clever concept

 

 

Cheers.   

[6./ZG26_Klaus_Mann]

By the way the 109 was scolded for the Slats, no. Really only the Germans and Russians used them as a practical way to get good manouverability with fairly small wings. 

The Brits used big or thick wings and the Americans, well, they didn't really care, and built comfy armchairs with guns. 

[Neil]

Indeed , this is a very clever concept to increase the lift at "low" speed.

Even used on this aircraft: the Morane saulnier Rallye (look at the blue one)

The first came in 60', many are still flying now. Known as a very very easy and forgiving plane.

https://en.wikipedia.org/wiki/SOCATA_Rallye_family

 

[6./ZG26_Klaus_Mann]

Almost All STOL (Short Take Off and Landing) Aircraft have some kind of Slat.  The Fi-156 for example. 

 

[EAF19_Marsh]

I believe the automatic / air pressure versions used on the 109 etc. are known as Handley-Page slats after the British aircraft company that first introduced them.

 

Not sure whey they were unused on many British / American aircraft as both were certainly aware of them. Possibly did not fit with the trends in their aerofoil designs?

 

EDIT : Maybe not, the spring-loading appears to have been a later aspect

Edited September 28, 2016 by EAF19_Marsh

[Finkeren]

One thing that always puzzled me was, that leading edge slats were never used on any of the carrier borne planes in WW2. You'd think they would be particularly useful there.

[JtD]

One Allied plane using leading edge slats was the Curtiss SB2C Helldiver. It also happened to be a carrier borne plane.

[JG13_opcode]

One thing that always puzzled me was, that leading edge slats were never used on any of the carrier borne planes in WW2. You'd think they would be particularly useful there.

Slats work best at high AoA, and most carrier aircraft would probably do better with less weight and a shallower climb.

 

Just a guess.

[Finkeren]

Slats work best at high AoA, and most carrier aircraft would probably do better with less weight and a shallower climb.

 

Just a guess.

I mean specifically for take off and landing.

One Allied plane using leading edge slats was the Curtiss SB2C Helldiver. It also happened to be a carrier borne plane.

Oh yeah, that's right.

 

It apparently also sucked big time (which is a shame cause it's a great looking plane)

[-=PHX=-SuperEtendard]

Another American carrier plane that had them was the A-4 Skyhawk

 

Edited September 28, 2016 by -=PLR=-SuperEtendard

[JG13_opcode]

 

 

I mean specifically for take off and landing.

 

That's what I meant as well.  IME, carrier take-offs usually are at pretty low AoA:  you pull chocks, rush forward, sorta sink as you clear the deck, and then speed up without climbing too steeply.

[ZachariasX]

Leading edge devices such as used on the Bf-109 or especially on the Skyhawk are high lift devices used mainly for takeoff and landing configuration. They are made to add to the deployment of the flaps. They are a substitute for the reduced lift of a smaller wing (that is chosen as it improves speed).

 

Willy built the Bf-109 with the thought in mind of making a fast aircraft. Slats are retracted then. Should you end up in very slow speed, in high AoA maneuvering (vary bad if you have one frag to give and are sitting in a 109, outnumbered 1:10 in average) then they will deploy for sure. HOWEVER, as these are controlled by airflow (and friction of the rigging) they often enough deploy not exactly at the same time, kicking off your aim and hitting your head against the canopy. Eric Brown noticed (and didn't like it about the 109) that as well as Skyhawk pilots who experienced the "head bang". When you had much less lift, such in the beginning of an approach, the uneven opening of the slats is felt much less, so it is fine there. But if they deploy at high g... *ouch*.

 

The slats made the Bf-109G being able to outturn the Spitfire IX at very slow speeds (according to Clostermann). But flying at 250 km/h is a bad habit in combat.

 

I'd be also careful to add delicate functionality to aircraft, that are used in the most coarse of all conditions, namely on carriers. You cannot control them, and should one get stuck, you loop into the sea.

 

Slats give you no more maneuverability. You fly fast in maneuvers. Slats give you shorter usuable runways.

[Dakpilot]

One of my more unpleasant flying experiences was caused by asymmetric slat deployment on takeoff  (max weight on an unusually hot day - 37 Deg+ )

 

The aircraft ( An-32) really wanted to roll inverted! , and diving towards the ground, over populated area at + - 150ft seemed very contradictory to survival instinct, even though this was the correct procedure 

 

Checks of cargo after landing revealed overload for density altitude..most times it is impossible to actually weigh cargo, and there has to be an element of trust, but this incident made me a lot more cautious and thorough

 

 

don't have a good pic with slats out

 

Cheers Dakpilot

 

[PapaFlo]

"The Bf 109s also had leading edge slats. When the 109 was flown, advertently or inadvertently, too slow, the slats shot forward out of the wing, sometimes with a loud bang which could be heard above the noise of the engine. Many times the slats coming out frightenened young pilots when they flew the Bf 109 for the first time in combat. One often flew near the stalling speed in combat, not only when flying straight and level but especially when turning and climbing. Sometimes the slats would suddenly fly out with a bang as if one had been hit, especially when one had throttled back to bank steeply. Indeed many fresh young pilots thought they were pulling very tight turns even when the slats were still closed against the wing. For us, the more experienced pilots, real manoeuvring only started when the slats were out. For this reason it is possible to find pilots from that period (1940) who will tell you that the Spitfire turned better than the Bf 109. That is not true. I myself had many dogfights with Spitfires and I could always out-turn them. 

One had to enter the turn correctly, then open up the engine. It was a matter of feel. When one noticed the speed becoming critical - the aircraft vibrated - one had to ease up a bit, then pull back again, so that in plan the best turn would have looked like an egg or a horizontal ellipse rather than a circle. In this way one could out-turn the Spitfire - and I shot down six of them doing it. This advantage to the Bf 109 soon changed when improved Spitfires were delivered." 

- Erwin Leykauf, German fighter pilot, 33 victories. Source: Messerschmitt Bf109 ja Saksan Sotatalous by Hannu Valtonen; Hurricane & Messerschmitt, Chaz Bowyer and Armand Van Ishoven. 

 

(I found this and many more statements about slats here: http://www.armchairgeneral.com/forums/showthread.php?t=139416)

 

I wonder if this "Bang" of the slats could be modeled - would be a cool feature, which iirc no other Sim has modeled yet. 

 

Flo

[ShamrockOneFive]

I mean specifically for take off and landing.

 

Oh yeah, that's right.

 

It apparently also sucked big time (which is a shame cause it's a great looking plane)

 

The slats were apparently fitted on the SB2C to solve low speed handling problems.

 

The early reputation of the SB2C was well earned. It was underpowered, short on range, poorly built, and on top of that... it was bigger, heavier, and not as agile as the SBD Dauntless that dive bomber pilots were used to flying. The SB2C-3 improved on nearly all of these problems and it ended the war with a good reputation. If we go to the Battle of Okinawa, the Helldiver will actually be quite a decent aircraft there.

[=362nd_FS=Hiromachi]

 

 

I mean specifically for take off and landing.

The other exception like SB2C is Japanese C6N carrier based reconnaissance aircraft, which was equipped with those. Leading edge slats and double-slotted Fowler flaps were incorporated into the wing to further increase lift, as well as ailerons could be lowered in conjunction with the flaps.

 

 

Source: Aviation of Japan blog

 

 

Though generally speaking its correct, for the most of the designs some kind of flaps would be chosen rather than slats. 

[69th_chuter]

The slats were apparently fitted on the SB2C to solve low speed handling problems.

 

The early reputation of the SB2C was well earned. It was underpowered, short on range, poorly built, and on top of that... it was bigger, heavier, and not as agile as the SBD Dauntless that dive bomber pilots were used to flying. The SB2C-3 improved on nearly all of these problems and it ended the war with a good reputation. If we go to the Battle of Okinawa, the Helldiver will actually be quite a decent aircraft there.

 

 

The SB2C, like the SBD (Speedy-Dee) and TBF/TBM, actually had slots, not slats.  Most WW2 planes not equipped with slats or slots typically used washout (wing twist) to accomplish the same thing:  the delay of stall at the outer wing.  Slat/slot equipped wings are invariably flat (untwisted) wings.

 

The asymmetric opening of the slats on the 109 often reported was due entirely to variations in airflow do to skids/slips (as often experienced in combat) and wing dihedral.  In other words, the AoA was different for each wing.  As long as the plane was flying straight ahead the slats functioned very much in unison. 

 

I've never seen "spring loaded" slats, they're either Handley Page (automatic - AoA controlled) or powered, like the Skyhawk (and all the planes I work on at SFO - lol).

Edited September 29, 2016 by chuter

[FlyingH]

The Lysander had slats too and I think the "Stringbag" Swordfish had them.

[ZachariasX]

Slat/slot equipped wings are invariably flat (untwisted) wings.

 

Lots of slats, lots of washout.

 

I've never seen "spring loaded" slats

Check out the Bf-109. Or the Morane Rallye, see below.

 

[...] or powered, like the Skyhawk [...]

These ones are reported of not even having a spring to push them out, but the open by gravity alone. Note how much downward they travel when opening:

 

The Morane Rallye in contrast had spring loaded slats:

Takes surprisingly little force pushing them in.

[ZachariasX]

The Lysander had slats too and I think the "Stringbag" Swordfish had them.

 

Yes, both had them, here open on the ground:

With slats like these, they could keep the flaps surprisingly small for a STOL aircraft. They close in flight:

 

With the Swordfish it's a bit different. That one didn't have flaps at all. But slats. Reatractable ones, but also bigger ones, note how these are open in flight:

[69th_chuter]

lol - OK. 

 

Regarding washout and slats:  I was referring to WW2 aircraft.  (We're getting our first A350s in a year and a half).

 

I have NO IDEA about the Rallye (seen 'em, not worked on 'em).  Worked on 109s (well, A 109) and there is NO spring on the slats.  AoA only.  On the ground they will sit either fully up or fully down (but nowhere in between) due to aircraft pitch angle and track profile.

 

I've been around a Skyhawk in a museum but haven't had much of anything to do with it, but I do know its slats don't move.  If they're AoA driven like the F-86 and 109 then someone must have "strapped 'em down" so they won't blow around in the wind or whatever, my bad.

 

If the Rallye slats take so little force to push them in are you sure there are springs?  I'm going to guess they don't unless you can confirm otherwise.

 

Whew.

[ZachariasX]

If the Rallye slats take so little force to push them in are you sure there are springs? I'm going to guess they don't unless you can confirm otherwise.

 

That I can confirm. I was a kid myself first time I saw that aircraft in France and *I absolutely had to push those in* (when nobody was looking) after my father told me about that speciality. They move rather straight in, so I guess there can't be too much of an AoA effect (unless at very high AoA).

 

 

Worked on 109s (well, A 109) and there is NO spring on the slats. AoA only.

 

Really? Well, funny enough just today I could show a Bf-109 to my kid but it was an Emil, no slats... so in this I can't comment on personal experience.

 

[Edit: Yes, on the E7 you have slats. But would be sad if you spent 15 mio. bucks and wouldn't even get slats...]

Edited September 29, 2016 by ZachariasX

[69th_chuter]

 ...

 

With the Swordfish it's a bit different. That one didn't have flaps at all. But slats. Reatractable ones, but also bigger ones, note how these are open in flight:

 

 

The Swordfishes didn't have flaps but I'm fairly sure they had flaperons.  Almost the same thing, on a serious budget - lol.

[ZachariasX]

The Swordfishes didn't have flaps but I'm fairly sure they had flaperons. Almost the same thing, on a serious budget - lol.

 

 

 

I don't think it had flaperons. These are just ailerons. You know, good aircraft can be affordable...

[69th_chuter]

On the E (like the later 109s) the slats can stay retracted on the ground.  If you grab the leading edge and pull it will resist slightly as it starts forward then quickly starts pushing itself the rest of the way down at about 1/3rd travel.  To retract it takes a slight force at first but retraction is the opposite of extension and it pulls itself retracted when about 2/3rds up.  It's like a marble wanting to stay on one side of a hump.

 

 

 

 

About the Swordfish's flaperons, I think you're right.  If you google images "Swordfish catapult" the second (or so) image shows a Swordfish being catapulted (good job google!) with eight degrees of deflection of all four ailerons but this flaperon feature may only have been for catapult capable versions.

Edited September 29, 2016 by chuter

[ZachariasX]

Don't tempt me touching the exhibits

 

[Crump]

 

 

The Morane Rallye in contrast had spring loaded slats:

 

I owned a Socata MS894A for several years.  Great airplane.

 

 

 

You can easily control slat deployment.   There is no spring assist AFAIK except to remove the friction forces of the connecting bars and the slats open by air pressure/gravity alone.   One of the biggest problems you will have as a Rallye owner is people on the TARMAC coming by and pushing your slats back in.  For some reason, all common sense leaves people when they see those slats and like moths to a lamp, they must come up and push them in.

 

 

Only thing I did not like was the slats are not allowed to deploy independently as the wing requires in the Rallye. The fact they cannot asymmetrically deploy makes for some heavy lopsided control inputs in steep turns and the force on the stick due to asymmetrical lift is noticeable when maneuvering.

[ZachariasX]

There is no spring assist AFAIK except to remove the friction forces of the connecting bars and the slats open by air pressure/gravity alone.

Yes, exactly, this is why they are so light. Or, why they "felt" so light.

 

 

For some reason, all common sense leaves people when they see those slats and like moths to a lamp, they must come up and push them in.

Much to my shame in this instance (even though I was a kid), this is VERY true.

 

Actually, thinking back what I did served me well as motivation to ALWAYS preform a thorough pre-flight check. There's not only kids and nutters around, there's also neglect. It served me very well in being very exact on that all those years. And flying club aircraft, you do find "findings" over time. I remember vividly the takeoff of a plane where pre-flight check was hurried (making matters worse, it was an old and well known instructor who pressed the student pilot forward) and watched it taking off and crash. Thank God it was only the plane that got damaged. "Kick your tires, light your fires, last one's off s'a sissy!" Not really.

[Crump]

 

 

"Kick your tires, light your fires, last one's off s'a sissy!" Not really.

 

Wise words....

 

Even in 121 land, pre-flight has saved my bacon more than once.