Good day fellow aviationists....
I have a question maybe one of yuh'all can answer..... (Or more than one!!)
I notice that typically, on passively deployed slats, there are always two...why two and not one? Or three?

thanks!!

All depends on wing style. A4's, had one. Some have two, segments deploying as each element of the wing's pressure changed. There is a structural advantage and weight savings with fewer segments. Each aircraft will have a bit of wing personality as it will be slightly different from the other. So much so that the Blue Angles, when they flew A4's, actually had hard fixed the slats up, since they would randomly deploy at slow speeds relative to the other aircraft in formation. It made if safer.

A7’s started with 1 per wing but transitioned to 2 per wing because long slats can bind on their hinges as the wing flexes. Most models with longer wings have multiple flap segments for the same reason.

Might be a disappointingly short answer, but there it is.

Also, on a GA airplane like the Helio or an SQ, there is wash or twist in the wings, so for the reason Cam noted, a single slat per wing would have to be twisted, and would bind. Plus, that wash is there to keep the tip flying into the initial stall buffet. So it makes sense to have the outboard slat separated from the inboard.

MTV

Interesting constant cord wings would have washout.....

Mithrandir wrote:Interesting constant cord wings would have washout.....

Most if not all wings on general aviation aircraft have some washout.

MTV

Oddly enough, I don't believe the Helio has any washout. I was quite surprised to hear it myself when I was inquiring a few months ago. Perhaps because with the slats the wing never approaches critical angle of attack so having different portions stall at different times isn't an issue?

One benefit is that wing rebuilds are easier because there isn't any twist to integrate.