Me410

[Karnak]

You can't fly slowly without the angle of attack that deploys slats at any speed.

You can fall slowly though.  Also roll along the ground. 

[GScholz]

The slats are not spring loaded or anything like that, and will gladly stay retracted on the ground at zero speed. However with airflow and angle of attack the slats extended when the stagnation point moves below the leading edge. The stagnation point is the point on a wing (section) leading edge, that marks the divide between air going over the wing, and air going under the wing. The slats are literally blown out from below the wing and sucked out from above. At low angle of attack the same forces act to keep the slat retracted.

[Karnak]

The slats are not spring loaded or anything like that, and will gladly stay retracted on the ground at zero speed. However with airflow and angle of attack the slats extended when the stagnation point moves below the leading edge. The stagnation point is the point on a wing (section) leading edge, that marks the divide between air going over the wing, and air going under the wing. The slats are literally blown out from below the wing and sucked out from above. At low angle of attack the same forces act to keep the slat retracted.

(Image removed from quote.)

Ah.  Did not know that.  Thought they were spring loaded.  Thanks for the correction.

[FLS]

You can fall slowly though.  Also roll along the ground. 

When referring to flight performance it's assumed that the aircraft is flying.

Slats are designed to deploy at an AOA prior to the stall. Since the stall is a function of AOA not speed, the slats are designed to deploy at the pre-stall AOA rather than at any particular speed since low speed doesn't cause stalls, AOA beyond CLmax causes stalls.

[Wmaker]

The slats keep the air flow over the wing from stalling up to a higher AoA and as lift coefficient increases linearily with AoA it provides a higher Clmax. Slats add 0.2 to the Clmax of a 109 for example.

[icepac]

If you can fly a slat plane without opening them, you won't experience the huge "E drain" the slats give you.

I only "get on the slats" when I'm willing to trade E for position.

[FLS]

If you can fly a slat plane without opening them, you won't experience the huge "E drain" the slats give you.

I only "get on the slats" when I'm willing to trade E for position.

Whenever you increase lift you increase drag. This is true for flaps, slats, or just flying near the stall at max lift coefficient. You are correct to avoid turning harder than you need to but slats are high lift devices not high drag devices. The design is very clever in that, unlike flaps, German WW2 movable slats only come out when you need them and they retract when you don't.

[Karnak]

Whenever you increase lift you increase drag. This is true for flaps, slats, or just flying near the stall at max lift coefficient. You are correct to avoid turning harder than you need to but slats are high lift devices not high drag devices. The design is very clever in that, unlike flaps, German WW2 movable slats only come out when you need them and they retract when you don't.

Developed by, if I recall, Westland in the UK.  The Mosquito was going to have them as well, but one flight testing they found it to be more agile than expected and decided it didn't need the slats so they omitted them.

[GScholz]

Handley-Page in Britain. They bought it from Gustav Lachmann who patented it in Germany in 1918. So it's an Anglo-German gizmo thingy.

[Karnak]

Handley-Page in Britain. They bought it from Gustav Lachmann who patented it in Germany in 1918. So it's an Anglo-German gizmo thingy.

Ah.  At work with no references so I was running on a fuzzy memory.

[GScholz]

I've read that Messerschmitt actually payed licence royalties to Handley-Page for the slats used on the 109 and 110. Never seen it substantiated in any way though.

[Karnak]

I've read that Messerschmitt actually payed licence royalties to Handley-Page for the slats used on the 109 and 110. Never seen it substantiated in any way though.

Seems likely as those are prewar designs.

[GScholz]

Yup. I've even read stories that Messerschmitt continued to pay royalties during the war, through banks in Switzerland. Again totally unsubstantiated of course, but it is not outside the realm of possibility. War or no war, business is business.

[Karnak]

Yup. I've even read stories that Messerschmitt continued to pay royalties during the war, through banks in Switzerland. Again totally unsubstantiated of course, but it is not outside the realm of possibility. War or no war, business is business.

Also possible.  I know Finland kept paying is loan dept to the US during the war even though we considered them hostile due to their alliance with Germany.

[FLS]

From Wiki: Slats were first developed by Gustav Lachmann in 1918. A crash in August 1917, with a Rumpler C aeroplane on account of stalling caused the idea to be put in a concrete form, and a small wooden model was built in 1917 in Cologne. In 1918, Lachmann presented a patent for leading edge slats in Germany. However, the German patent office at first rejected it as the office did not believe in the possibility of increasing lift by dividing the wing.
Independently of Lachmann, Handley-Page Ltd in Great Britain also developed the slotted wing as a way to postpone stall by reducing the turbulence over the wing at high angles of attack, and applied for a patent in 1919; to avoid a patent challenge, they reached an ownership agreement with Lachmann. That year a De Havilland D.H.9 was fitted with slats and flown