Max CL and its effect on performance

[pasoleati]

Well, IMHO it seems that would have been enough span left outboard the wing guns to fit slats.

F4UDOA, could you perhaps supply me a copy of the entire SETP eval report of those 4 fighters? I have seen quotes of it, but not the entire one.

If you can, contact me at paso.leati@@reppu.net (del one @)

[MiloMorai]

Originally posted by pasoleati
Well, IMHO it seems that would have been enough span left outboard the wing guns to fit slats.

Do you mean like this?


The early P-51s had cowl mounted mgs.

[Crumpp]

The slats sometimes had the habit of opening up when hit by rough at high speed.

Interesting.  Made me think of the propwash thread.

Crumpp

[Kurfürst]

Originally posted by Angus
Ooff, from memory again.
The slats sometimes had the habit of opening up when hit by rough at high speed. (On the 6 of an enemy plane it was often a tad rough).

[/B]

IIRC Eric Brown commented this. But then again, propwash that caused it throws around any plane a bit, so again not really related to the installation of slats.

The high deflection shots are worth looking into, - most kills were made at very low deflection.).

[/B]

Most fighters didnt have slats in WW2. ,)

[Angus]

Well, Izzy? (I rather suspect so), Some of the most common fighters of WW2 (109, lala) Did have slats.

Some of the 109''s pilots chose to shut those though.

In AH, they work marvelously, if it is a good representation of the real life, I'd like them.

BTW, they don't seem to be so common on light aircraft today. Why comes? Too expensive?

[pasoleati]

Well, it is indeed due to costs that these lightplanes are simple blasphemy to real enthusiasts!

BTW, it might be worth adding that Frederick Handley-Page (or the company, don´t recall) got some aviation safety prize for these slats before the war. This was mentioned in Putnam´s marvellous "Handly-Page Aircraft" book.

[HoHun]

Hi Angus,

>The slats sometimes had the habit of opening up when hit by rough at high speed. (On the 6 of an enemy plane it was often a tad rough)

For all planes, slats or not :-)

In fact, if it became really rough, the slats were beneficial because they could prevent flick stalls. Douglas Bader during the Battle of Britain once climbed up to the six of a Heinkel bomber he was trying to intercept - only to spin out immediately when the wake hit him. Asymmetrically deploying slats would have prevented the spin, even if the fighter might have been thrown around.

>Todays fighter jet slats are deployed how?

I believe slats have been mostly replaced by drooping leading edges from the F-16 on. However, Handley-Page slats were used on the Me 262, F-86, A-4 and F-4 (for example), so they remained principally unchanged for decades.

I'd speculate that the change to different principles (if I'm right there, I'm no jet expert) might be connected to the introduction of computerized flight controls systems with the F-16 generation of, jets where a higher degree of control by the FCS might have been desirable.

Regards,

Henning (HoHun)

[HoHun]

Hi Angus,

>BTW, they don't seem to be so common on light aircraft today. Why comes? Too expensive?

Roger that. Moving parts, always a major cost driver.

It's often said that the 1930s' Bf 108 is still technologically on par with the typical Cessnas, Pipers and Robins that are around today, but I suspect that if you compare prices, you'll find that the beautiful Bf 108 was several times as expensive then these :-)

Many aircraft are using fixed slats instead of the automatic ones, including some modern STOL aircraft.

Regards,

Henning (HoHun)

[Angus]

I've seen a 108 flying actually.
A purring beauty

Oh, this:
"Asymmetrically deploying slats would have prevented the spin, even if the fighter might have been thrown around. "

That was the problem I belive, at least on the 109.
The slats did not deploy that way. You could have one of them clonking in and out for instance, - i.e. in a turn.

One very beautiful aircraft is a WW2 era Dornier, just can't remember the model.
Well, it's a 6 person (or so) tail dragging upper wing aircraft, probably an army liasion plane or that sort of stuff.
It has a somewhat powerful engine I belive, and quite some wingspan (It's quite a bit bigger than a Cessna 172 for instance)
It has front mounted fixed slats.
The Stalling speed is 27 knots as far as I remember.
Very short takeoff roll as well.
I'll se if I can find a pic-link for it

[Angus]

Ahh,look here.
Nice one.
Resides in Iceland BTW.





if link does not show picture, press here:
http://www.islandia.is/aeroweb/islenski_flugvefurinn/mulakot/pages/mul01_1493m-14_tflds_png.htm

Don't know why....

[HoHun]

Hi Angus,

>>"Asymmetrically deploying slats would have prevented the spin, even if the fighter might have been thrown around. "

>That was the problem I belive, at least on the 109.

That was not a problem, it was a solution :-) Asymmetrically deploying slats restored symmetrical lift. No slats, asymmetrical lift, you roll or flick.

>You could have one of them clonking in and out for instance, - i.e. in a turn.

At a certain Cl, they were either in or out. Pump the stick, and they come in and out. Stick pumping is not good for you aim anyway :-)

>One very beautiful aircraft is a WW2 era Dornier, just can't remember the model.

You had me puzzled with this one :-) It's actually a post-war aircraft, the first to see production in Germany after WW2.

Some of these are still flying, they are very good STOL aircraft indeed. The real jaw-dropper is the Storch, of course, it's not really flying but ridiculing gravity :-)

Regards,

Henning (HoHun)

[Kurfürst]

Originally posted by Angus
Well, Izzy? (I rather suspect so), Some of the most common fighters of WW2 (109, lala) Did have slats.

Hmm, what I can think of is the 109 (plus all other Mtts)and the Lavochkin 3/5/7 . Thats indeed a nice number produced, but still uncommon if you look at all fighters produced in WW2. Yaks, P-series, Spits/Hurris and so on.. cant think of a jap. fighter that had them neither. On the second though, Junkers liked the idea, too, using his own patented trailing edge slats.

Some of the 109''s pilots chose to shut those though.[/B]

I find that rather hard to believe, for one I havent seen any actual proof of that, its much more like an urban myth like many regarding the 109. I guess the only time a 109 had its slats locked was probably when they were damaged and there werent time to fix them before flight etc.

BTW, they don't seem to be so common on light aircraft today. Why comes? Too expensive? [/B]

Maybe. But then I think they are not neccesary. Ad1, light hobby aircraft have generous wing area and lift, and are usually shoulder-winged types (which comes with great stability). Plus slats only help at high AoA, ie. hard turns a fighter is likely to perform, but I doubt any sensible, or at least not insanily rich man would pull 6-7 Gs with a Cessna that isnt designed for such loads in the first place.

[MiloMorai]

Do any of the modern aerobatic a/c have slats?

Any WW2 era trainers have slats?

[Angus]

Slats do help on slower aircraft and nicely at landing or slow speed handling. They were popular in the 30's.
As I have showed also, slats are good on "bushplanes" as well.
I think they were definately no kind of genious invention for high speed and high G maneuvers, bur rather as a stall-aid.
If German aces did not prefer those in combat (and I did see Rall say that actually, so there goes the urban myth), that would support that. I will find something more there, gimme a bit of time.
There are many allied planes that could have had them, after all, they were not a novelty.
A P38 with slats? Hurricane? Spitty, if you skip the outboard mg's.(some pilots had that done as field mod).
Didn't some jap planes have slats?
Anyway, why did the US go for the combat flap instead? And Japs?
Were they silly or what?

[HoHun]

Hi Angus,

>Slats do help on slower aircraft and nicely at landing or slow speed handling.

Messerschmitt shelled out 2 million Reichmarks to investigate whether he should keep the original locking mechanism that restricted the use of the slats to landing and slow flight, deciding that the way to go was to allow them free operation, and you wipe away this decision (based on countless test flights) with one push of a button? :-)

Don't try to deceive yourself, Angus. The Me 262, F-86 and F-4 are no slow "bushplanes", but a hell of a lot faster than the Me 109, and Handley-Page slats worked great for them.

>Were they silly or what?

The slats are an inherent part of the wing design, you don't just slap them on as an afterthought. The Spitfire for example didn't use slats, but relied on wing-twist (washout) to retain aileron control at high angles of attack. The Me 109 on the other hand had a "straight" wing, no washout at all, which is quite efficient but calls for some other device retain full aileron control at high angle-of-attack.

If they fit your design philosophy, the Handley-Page slats are excellent, but they don't fit it every case.

Regards,

Henning (HoHun)