109G/la-5/7 and the slats

[HoHun]

Hi Angus,

>Now don't get too pompous mate.

Well, I can rephrase it:

There's no dead body, and there's no smoking gun.

All you've got is a modern textbook saying that people get murdered occasionally.

You have no case against the Me 109.

Regards,

Henning (HoHun)

[eilif]

with all the energy you two are putting into this moot argument you might as well focus on world peace.

[Overlag]

fly smart and smoothly and the slats dont snap out....

[Angus]

Hello again HoHun.
Your nerve seems to be the 109, since it has slats.
All I've got is a modern textbook, and some anecdotal data pointing at roughly the same thing.
All you have is nothing, resulting in total refusal.

Just surfed the almighty internet looking for info on slats.
To my surprize, I actually found something mentioning icing problems BTW!
Didn't find a smoking gun, just bodies with holes in them.

Regards

Angus

[HoHun]

Hi Angus,

>All you have is nothing, resulting in total refusal.

You're the one to make claims, you're the one who has to bring the evidence.

You haven't brought anything, so I can't refuse anything.

You want to prove the Me 109 slats had problems, you bring proof specific to the Me 109.

One single claimed (but unverified) quote from one pilot who reportedly said something vaguely negative on the slats is worth nothing, and you haven't even posted that quote verbatim yet.

All the modern day sources might be very useful for assessing the documents you might dig up on the Me 109 - but no documents, no use.

These are the rules of the game, and these rules were not made by me, but by scientists like von Ranke and the historians building on this foundation in the centuries that followed.

Ignore these rules, and you'll find yourself on my ignore list. Nothing personal, just that we're lacking any basis for rational discussion then, and it'll certainly save both of us a lot of time.

Regards,

Henning (HoHun)

[Angus]

Dear HoHun
My evidence from a ISBN numbered techbook (for the IAR) has to do with automatic slats in general. Nothing specific about the 109 as I have said before.
So, tell me, was the 109 slat design so unique, that general concepts as analyzed with todays methods do not apply to them?
Please bring some evidence pointing the other way, for if you mention "rational discussion" that should apply to yourself also.
I will however not put you on my ignore list, - generally I rather find the stuff you bring on these boards to be quite good.
Best of luck

Angus.

[Kurfürst]

Hmm, rubber tires can go bye-bye anytime, usually during landing or tekoff. This caused many, many ugly accidents. The plane can groundloop, turnover, the fuel tank raptures and then only a spark is needed and everybody inside burns alive.The most recent one put the Concorde in past tense, for example.

I heard the Spitfire had those rubber tires, Angie....
etc.

Can go wrong and did go wrong. Do you percieve the difference between ? See how wrong your logic is ?

[Angus]

Did somebody mention tyres here? Or the Spitfire?

Stick to the point, so tell me Izzie, do you think there is any truth in the myth of slats causing an uncomfortable movement of the aircraft while deploying?
If yes, would you think it is a general issue or a maintenance/calibration issue?

[OOZ662]

Man, I read 3/4 or so of this thread...

You people need somethin to do! All I know is, the slats in the game piss me off. Every time I get someone in the gunsight, my plane clunks and rolls over like ten degrees. Give me a welder and I might fly the luftwobble planes more often. I don't care how violent a roll the wings would give without slats as long as the a/c holds topgether through that roll. So some people liked slats, others didn't. Big whoop. The question was "Do slats effect performance" and it turned into "I can prove you right/wrong about whether or not pilots liked slats"

You guys want evidence that simple machines (including rollers on a track) eventually will not work as well? Go out on yer bike, wash the chain free of oil, WD40 it and throw some sand/dirt on it and ride it. Repeat the same number of times as a 109 would've taken off/landed between the times that the ground crew would come over and clean the bastages.

So: Common sense says that if it gets dirt it won't work as well. If it doesn't work as well, performance suffers.  The squad leader who had his slats cleaned/oiled every five minutes liked the slats, while the poor nerd that never even got a drop of oil in his didn't like them.

[Angus]

Exactly.
I have 2 barn doors running on roller tracks, right now, neither of them is ok.....

[Charge]

The G2 and G6s were flown in Finland very much from fields with tended to dust much and I have never heard there was a problem with slats.

Wasn't there a different mechanism for slats in early 109s which was prone to jamming? After they changed it the problems pretty much ended. Not sure about this...

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.

A Veteran who flew the 109s after the war told me that they were taught to "pull" the slats open prior to landing so that on short runways of Finland the landing distance was considerably reduced. But it is strange that the Finnish veterans' comments on slats are scarce so it leads me to believe that that the flight envelope in fights was usually such that the slats did not usually deploy and when they rarely did they usually worked OK.

-C+

[Tilt]

In level flight Lavochkin slats were set to extend at the AoA required to fly at approx 210 Km/hour IAS.

Hence they always deployed during landing.

When the ac was at rest they swung closed under gravity.

The mechanism is very light..........I can pull the lavochkins slat open with my little finger. The construction is simply a curved alluminium profile hinged via a pair of (parrallel) lever arms.

The angle of the lever arms seems to determine the point at which they are sucked out and so this (plus some tinkering with the shape of the profile) will allow fine tuning.

Once the AoA and air speed combine to extend or retract the slats the effect is amplified as it opens or closes causing the action to be rapid.

It can be seen that a low speed ruddered barrel roll type manouver will cause the slats to open at diferent times as each wing has a different AoA.

IMO

Extending the slat does not bring about a massive change in lift.

Infact it merely maintains clean air state to preserve the lift.

However as the AoA increases further the loss of clean air state is rapid and so final departure characturistics  quite violent particularly when performing manouvers that favour one wing over another.


To this end the slat does not cause early departure it actually prevents it............if you then ignore the warning it provides more fool you.

As to a reliability issue. if I look at the myriad of things that are subject to maintenance and yet effect the characturistics of an ac the Lavochkin slat this is among the least of them all.

The list of more complex, more maintenance heavy, even more critical items is very significant.

[Kurfürst]

Originally posted by Angus
Did somebody mention tyres here? Or the Spitfire?

Stick to the point, so tell me Izzie, do you think there is any truth in the myth of slats causing an uncomfortable movement of the aircraft while deploying?

No. At least not on 109F/G/K.

"One interesting feature is the leading edge slats.  When these deploy at low speeds or in a turn, a 'clunk' can be heard and felt, but there is no disturbance to the aircraft about any axis. I understand that the Bf109E rolled violently as the slats deployed, and I am curious to know the difference to the Gustav that caused this."

I think this is hard to be argued upon.

Now the statement that the 109E "rolled violently" is by 90% chance based on the RAE`s report on captured Emil, who had no experiance with it`smaintaince prescriptions. It was handed over by the French, after it belly landed, and later it was found it`s fuselage was bent in the process...

This 109E report said BTW:

"With flaps up the ailerons snatch while the slots are opening, and there is a buffeting on the ailerons as the stall is approached.. With flaps down there is no aileron snatch as the slots open, and no pre-stall aileron buffeting"


Now Gripen in one of his rare brighter moments suggested that this aileron snatching could probably due to the aileron design of the 109E, which was changed to Frise type ailerons from the 109F onwards; the the flap interconnection with the ailerons was also given up.

If yes, would you think it is a general issue or a maintenance/calibration issue?
[/B]

I don`t think it was ever much of a problem. Of course both damage, if the part was not replaced, could cause it, bad calibration could naturally cause it as well. But that`s hardly a slat-only problem. Poorly choosen pairs of ailerons, elevators, plus if they were badly calibrated as well could cause far more serious problems. The slats were maintaince/calibration free compared to those.. ie. Mike posted some 109 regulations on the ailerons on the spit propaganda site. Regardless of his intentions, these also say that as little as extra paint on the aileron surfaces can have effect on their behaviour (most likely this would increase the chance of flutter due to poor balancing).

Just as a sidenote, on the 109K the slats were made of steel instead of light alloy, perhaps for saving material, or to decrease the workshop`s task, but it can be they also wanted to increase their durability.

[Angus]

So the myth could originate from early type 109's since their aileron design was inferior to the F model onwards rather than a maintenance/damage issue?
I'll have some info on this probably tomorrow. Will keep you posted.
Anyway, some stuff is emerging and it's interesting.
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.

[HoHun]

Hi Ooz,

>You guys want evidence that simple machines (including rollers on a track) eventually will not work as well?

Actually, that's not what I want :-) What I want is evidence that slats on the Me 109 were a problem.

It's not that I can't imagine there might have been technical difficulties. I have a vivid imagination, so that's easy for me :-) However, I can just as easily imagine Luftwaffe ground personnel being able to prevent these problems by simple maintenance measures.

It's not about what one can imagine, it's about what one can prove.

For example, almost all of the effects that harm slats can harm pitot tubes as well. For the RAF night bombers, a malfunctioning or even a slightly bent pitot tube could spell desaster. Even if the bomber might not spin out in the clouds, or crash on landing, a pitot tube that went out of calibration would mess up navigation, causing the bomber to miss its target, or worse, get lost over enemy territory and run out of fuel, forcing it to glide to a crash landing in German-occupied France, or to ditch in the channel, possibly killing all aboard.

Still, I have read testimonals of RAF bomber crewmen by the dozen, and no one ever mentioned the lethal menace of a poorly-maintained pitot tube.

The obvious conclusion? There were no poorly-maintained pitot tubes in the RAF because the RAF personnel took good care of them.

And lacking any evidence to the opposite, the conclusion regoarding the Me 109's slats must be the exact analogue.

Regards,

Henning (HoHun)