109G/la-5/7 and the slats

[Angus]

Hello HoHun.

The RAF as a whole, never managed to keep perfect maintenance, especially when things got really hot. Of this I have quite some data, some anecdotal, some from biographies.
I know instances where aircraft flew multiple sorties without any speed measuring device (petout problem perhaps?), with holed wings, jammed guns after having been loaded by the pilot etc etc.
Yet, I'd think that the LW would have even more difficulties with this issue, especially late war, and especially on the eastern front.
So, still bogged in with the same speculation.....

[Charge]

Angus: "BTW, someone mentioned that the slats did not affect lift that much. I always thought they did (By increasing it.) Any comments on that.
They also come with a drag penalty when deployed, so that rater supports it, - nothing is free."

I don't know, but I'd imagine that the slat itself does not increase the lift but enables the wing profile to tolerate higher AoA than it would be possible otherwise.

I'd also imagine that the moment before the slat deploys could be the worse moment as the air flow is highly turbulent on top of wing thus creating drag. The slat deploys and uniforms the flow thus decreasing drag caused by turbulent airflow. If the slat is tuned properly if deploys before the turbulent airflow causes any significant drag.

What I wonder is what kind of effects does the changing leading edge profile have on the lift qualities as is the case with Spitfire which suffers aerodynamically in turn if the gun ports are open.


Anybody who knows these things care to comment?

-C+

PS. "nothing is free" <- You said that Angus, and this is the case with all aircraft, of course... ;-)

[niklas]

Originally posted by Charge

BTW in banking turn your wings have different airspeeds which, of course, may force the lower and inner (to turn) slat to open earlier which can cause undesirable effects especially if you are just about getting a gun solution on enemy. Nothing radical, probably, but enough to throw off your aim momentarily.
-C+

Ahh no. A 109 is not a slow sailing plane that turns on a dime. Just think:
If a 109 turns at 60° angle, the difference of the middle distance of the slats (assumed to be 9m) becomes only 4.5m in the horizontal.
Assuming a turn at 360km/h, 20seconds turn time, the circle path would be 2000m, or a diameter of ~640m !

The difference of the slat travel way would be only 14m for a full circle compared to 2000m of the whole machine, less than a percent. Neglectable...

niklas

[rshubert]

I was looking at a Discovery Wings show about 262s a few weeks ago.  It was interesting to see the captured training films, showing a LW crewman doing a walkaround.  Part of the walkaround was to check the free movement of the leading edge slats, and make sure they were free to move.  From the look of what the mechanic was doing to free up the slat, there was more risk of the slat sticking against the wing leading edge than of a roller sticking.  He simply bent the back edge with pliers to free it up.

By the way, the aerodynamic effect of the slat is to "blow" air over the upper surface of the wing at high AOA, thus delaying stall onset, maintaining smooth airflow over the top of the wing.

[Staga]

Angus; Hasn't anyone told you slats were patented by Handley-Page, you know that British aircraft manufacturer?
Are you aware that for example earlier Handley-Page Halifax bombers had similar slats to help slow-speed handling and that those were removed when the wing leading edge had to be strenghtened?

They were British inventions; Shouldn't you be proud they become so popular in Messerschmitts and are used even today in just about every fighter and passenger aircraft?

Oh I'm sorry; You already decided they suck.

[Angus]

I am very well aware the slats were a British patent.
I am also aware that the Brits stopped using them.
I am very well aware that as soon as I touch a 109 nerve, there will be mentioning of Spitfires and British problems.
I am very well aware of the myth that some 109 pilots did not like the slats, some are told to have them shut, some complain about them momentarily throwing off their aim.
I am not discarding the myth alltogether.
I am trying to get to the bottom of it.
I am very well aware that most modern passenger aircraft have slats, however NOT automatic ones.
I am also aware that most light modern aircraft do NOT have them at all.
I am also trying to figure that one out.
I have not come to the conclusion that they suck, on the opposite, almost everything I have dug up rather supports the automatic slats as a very clever aerodynamic devise.
I have flagged the theory that the myth could originate with malfunction, damage or such, rather than the aerodynamic design or function.
Yet, the 109 nerve seems to hurt a bit.
I do not quite understand why Staga assumes I should be proud of that British patent. Why should Staga not him/her/it-self be proud in the same way. I am not British by the way.
I shall find out more about slats in the near future.
I shall post some here as soon as I find some.
I am ending this message.
I say goodbye.

[MiloMorai]

And it was, afaik, a German working for H-P that did the design work, or something like, that for the slats.


Angus, you should know by now that the ultimate fighter was the 109. It was perfectection personified.

[Crumpp]

Yet, the 109 nerve seems to hurt a bit.

Watch that 109 nerve it is very sensative.



Crumpp

[Oldman731]

Originally posted by Crumpp
Watch that 109 nerve it is very sensative.

Lol.  Do tell.

- oldman

[HoHun]

Hi Oldman,

>Lol.  Do tell.

Well, this is really strange, but no other fighter seems to attract as much malice as the Me 109.

I'm just as ready to defend the P-51 - which I consider the best fighter of WW2, and better than the Me 109 - against poorly researched myth-building attempts as the Me 109, but somehow, that's hardly ever necessary.

(Ironically, the P-51 with its somewhat harsh stall might have actually benefitted nicely from slats, and North American's next design in fact borrowed them from Messerschmitt :-)

US fighter planes generally are discussed rather more rationally than Luftwaffe fighter planes for some unfathomable reason - the three gentlemen who posted above all qualified for my ignore list during Me 109-related discussions, and I add people to that only for irrational behavior, not for any particular point of view.

Regards,

Henning (HoHun)

[Charge]

Gather all trolls to toss yer poop...

-C+

[Angus]

Hello HoHun.
I may have earned myself a place on your ignore list (well, I am fourth from above), but you have not entered mine. I consider all input worthy of looking into, unless it is tweaked, which is fortunately not so common on this board.
Anyway, I just wanted to tell you about a link (emmm, maybe I did already) about flying characteristics of 109G, the slats and a turn capacity compared to P51 and Spitfire.
It's there somewhere in the Spit I turning thread of this board.
(Video interview)
Anyway, the guy is absolutely fascinated with the 109G's slats.
Taking for granted that they are in perfect order, he seems to be very happy about their stall/lift performance enhancement.
"Turns on a dime" he said, while the P51 "does not turn at all" and bleeds energy very quickly.
Have a look if you haven't already.

Regards

Angus

[gripen]

I think  it's fun to be in HoHun's ignore list; dispersion thread is a good example

Regarding slots, I think those were absolute great But I think the Russians designed mechanically better slots to the LaGG-3/La-5/La-7 than the Germans to the Bf 109.

gripen

[Staga]

So what was the difference between German and Russian slats and why were those better?

[gripen]

The Russian design was a simple sideways hinged device which eliminated all loosenes. IIRC also the late MiG-3s had similar slots. Maybe Tilt has some pictures.

gripen