Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: 1K3 on October 23, 2004, 12:52:50 AM
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Do slats have negativce effect (like sudden "snaps") on 109Gs/la-5/7 in r/l if you pull the stick suddenly @ lo-turning speeds? I notice that slats dont always come out evenly and i think that's what's causing the 109G or la-7 to snap in AH2.
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Frankly, the slats feel like a hinderance rather than help.
Or, if the 109s maneuver that unstably even with the slat assists, I'd hate to think what it would be like if it didn't have slats at all.
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Originally posted by 1K3
Do slats have negativce effect (like sudden "snaps") on 109Gs/la-5/7 in r/l if you pull the stick suddenly @ lo-turning speeds? I notice that slats dont always come out evenly and i think that's what's causing the 109G or la-7 to snap in AH2.
It was a problem in reality too. Some 109 pilots wired the slats shut.
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Slats extend above local AoA and so under some conditions one wings slat may extend prior to another.
Whilst delaying departure as the AoA increases they have the characturistic of very rapid lift loss at the eventual departure point.
On the La 5/7 I believe HTC have modelled a fairly violent wing dip at this point which I believe is a function of the prop influence. (The shape of the la wing puts a lot of it behind the prop.)
The 109's just seem to "mush out" but I dont fly them that often to comment really.
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the 109G series.. and F for that matter should have the slat deplying seperately. Only the E series should pop both at the same time. This was a problem for the LW in the early 109s. I believe that the G series was supposed to be the more "touchy" of the bunch.
That's why I LOVE my F4! :D
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http://www.hitechcreations.com/forums/showthread.php?s=&threadid=132616
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Originally posted by Karnak
It was a problem in reality too. Some 109 pilots wired the slats shut.
Urban myth. They didn't.
It's been suggested, that this might have happened in the desert conditions.
However, there hasn't yet been a single source showing evidence of this practise, and aviation museum cutators, Messerschmitt 109 pilots or Me 109 expert s I've asked if they've ever heard about such practise have said they've never, ever heard about such thing, and dismissed it.
So no, by current information, 109 pilots didn't wire their slats shut.
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From an interview with Franz Stigler (109 ace):
"Did pilots like the slats on the wings of the 109?
Yes, pilots did like them, since it allowed them better positions in a dogfight, along with using the flaps. These slats would also deploy slightly when the a/c was reaching stall at higher altitudes showing the pilot how close they were to stalling....this was also useful when you were drunk!"
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Gunther Rall did not prefer the slats, and urban myth claims that the pilot that wired them was actually Hartmann.
I may have the explanation for this.
From a Commercial Pilot aerodynamics teaching book:
(Very very thick)
"Principles of flight",ISBN 91-973123-1-2
Section 8.9
"Some aircraft are equipped with automatic slats. These are hinged in such a way that the press distribution at high A.o.A. pushes the slat forwards/downwards at high A.o.A.
That kind of automatic slat has to be very well balanced and glide easily to have the desired effect. A slightly damaged automatic slat may open at higher A.o.A. than the normal opening one. This will cause assymetrical lift and unacceptable roll disturbances at high A.o.A."
Pretty much tells out loud what some of those old 109 pilots were saying, - that the slats were throwing them off their aim.
In a perfect world slats like these were of course wonderful, but is wasn't a perfect world you see.......
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Angus, you think that Messerschmitt equipped his 109s with "slightly damaged" slats? :)
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Equipped? No.
Do you think all 109's from combat and dirty field were always in perfect condition?
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Angus, do you think that if the 109 pilots didn't like the slats and were wiring them shut, that Messerschmitt would have continued to incorporate the slats in 5 years of 109 designs from the E model to the K?
I don't think so.
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I think it would have been a matter of opinion, and especially under difficult circumnstances, delicate mechanism is the first to suffer.
Have to deal with that kind of stuff every day. ;)
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There is nothing delicate about the slats. Two massive hinges and a metal slat, that's it. No springs or any mechanism at all, it's no more complicated than a door.
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Hi Angus,
>I think it would have been a matter of opinion, and especially under difficult circumnstances, delicate mechanism is the first to suffer.
You're making up a problem where none existed.
Bad style, Angus - where's your evidence?
Regards,
Henning (HoHun)
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So what are these slats supposed to do?
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At higher AoA (angle of attack) wings tend to stall; when slat pops out it changes the wing profile little and also creates a slot from where air bleeds from wing's under surface to the upper surface and helps airflow to stay in contact to wing and not become turbulent, if it happend wing loses lift = wing stalls.
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From some things that I've read, the slats deploying at slower speeds and in turns, especially if they deployed at different times, made the 109s and 110s a little more unstable as a gun platform due to the uneven deployment. Basically, geting a target in sights, following it, then have a slat deploy - loose target sight and correct, sometime over correct...trying to regain target sighting.
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Originally posted by GScholz
Angus, do you think that if the 109 pilots didn't like the slats and were wiring them shut, that Messerschmitt would have continued to incorporate the slats in 5 years of 109 designs from the E model to the K?
I don't think so.
Its 10 years, the slats were there the whole time.
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Originally posted by Angus
Pretty much tells out loud what some of those old 109 pilots were saying, - that the slats were throwing them off their aim.
In a perfect world slats like these were of course wonderful, but is wasn't a perfect world you see.......
You keep beating a dead horse.
You keep claiming 109 pilots didnt like slats, but you failed to come up with ANY evidence. You keep pointing to several well known pilots, failing to support the claim with a quote and source from them.
As HoHun put it, you simply made up a problem that never existed in real life, and keep boxing the air, pulling out "evidence" from you magic hat, but none can see it.
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HoHun and Izzy:
Look again, this is from an aerodynamic teaching book for professional pilots:
""Some aircraft are equipped with automatic slats. These are hinged in such a way that the press distribution at high A.o.A. pushes the slat forwards/downwards at high A.o.A.
That kind of automatic slat has to be very well balanced and glide easily to have the desired effect. A slightly damaged automatic slat may open at higher A.o.A. than the normal opening one. This will cause assymetrical lift and unacceptable roll disturbances at high A.o.A." "
ISBN can been seen if you scroll up.
The second thing was from Rall.
Straight from the Horses mouth:
"The 109 had slats which I didn't like"
If you want me to I can mail you his voice saying this, umm, and some other words you really would not like to hear.:D
But my point anyway, is that as my textbook gives, that if the slats were in insufficient condition, they could become a liability instead of an advantage.I have no problem with that.
The benefit from slats would be absolute if they could be kept in good condition at all times thereby.
I can dig something up, but this is authentic, I have given the source quotes and the ISBN. So stuff it Izzy
:D
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Ok, keep beating it Angie. And of course, lets hear Rall saying this, you know my email, you can mail it right away - if it exists.
And the other things I may not like from the 3rd highest scoring Bf 109 pilot, oh, who happens to be the 3rd highest scoring fighter pilot, too. Only God knows if its a coincidence.. :D
But the main thing still is:
ANGIE DIDNT FIND ANYTHING THAT WOULD SAY 109s HAD PROBLEMS BECAUSE OF THE LEADING EDGE SLATS. NOT ONE.
So stuff up the pitch fork you work with everyday, oh my brother suffering from an extreme case of 109-envy. :aok
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So you assume every 109 had damaged slats ? Maybe even delivered this way from the factory?
Slats alone don´t give you more lift. They allow higher AoA, that´s all. They prevent the wing tips to stall earlier than the inner part, thus the ailerons keep effective and the aircraft can be kept controlled while the inner part of the wing is already stalled.
Asymmetric opening could have been avoided by adjusting the ailerons. Beauvais mentioned it once , but they got the instructions late in Rechlin. Brithis pilots definitly didn´t know about it. The aileron snatch was fixed with the F afaik.
But of course this slat-feature was just there to be a nuisance for the pilots, the 109 did fly and land much better without them, and the slats over the whole wingspan for the 262 were of course just a consequence of the upcoming madness of Messerschmitt as we all know..
niklas
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Ah, of course a 109 would be the only aircraft in the world with maintenance free and problem free slat system?
They must be teaching todays pro pilots a lot of nonsense I guess.
Ralls words are actually on video. I'll have to transfer it to tape somehow, or rather mp3.
Email as on these boards?
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Angus you are trying to make up a problem where none existed. There were no chronic 109 slat problems reported, never. If some guys didnt like them so what?
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Angus, you should know better than never mention anything that shows the Me109 was anything but the ultimite fighter of WW2. :rofl
I see Barbi has re-registered with a new nick. Still his old self.:D
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There were no special chronic slat problems for the 109.
They are universal, that's all.
They need to be maintained well, if not, they do not operate in the desired way.
That's where I belive the myth of snapping plane due to slats originates from. Not from the factory, nothing to do with the all-holy 109, just due to combat related maintenance problems.
Clear enough?
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Originally posted by Angus
Ah, of course a 109 would be the only aircraft in the world with maintenance free and problem free slat system?
Email as on these boards?
Angie PRAY tell me WHAT can go wrong in freaking metal plate, that is attached to two rollers travelling on a rail(?), moving only if the air pressure on the metal plate is too low?!! NO MECHANICS involved! Wishful thinking I guess. The flight stick alone was 100 times that complex. A slat is a most simple device, developed on the tech level of WW1, effectively "maintained" and produced (what maintance does it require at all?) even in the Soviet low-tech enviroment, does that fact even remotely penetrated that thick skull of yours?
I just wonder WHY you are so stubbornly persist that there was a problem with them, when theres absolutely no evidence pointing to that...
Email, yep.
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Your prayers are answered.
What can go wrong?
Well, the slats have to be very well balanced and glide easily to have the desired effect.
So, mud, ice, and lack of lube, dents, holes, rust and so on come to mind.
The LW had a hard time keeping their aircraft fully operable towards the end of the war, we all know that. So please don't get me wrong, the princip of the automatic slat is very good indeed aerodynamically. But if they don't work completely perfectly they become a liability.
I'll see what more I can find anyway.
(Something more proper)
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The slats on the first F86 where taken from a 262 according to World Airpower Journal.
I read one pilot that said the problem with slats was that many inexperianced pilots would feel the stall coming and let up, not forcing the turn a little more and deploying the slats. So they never knew how manuverable the 109 was.
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Yup, F-86 Sabre had identical automatic slats like the 109. Nothing strange in that system.
And for one quote about slats being poor I can find two from pilots, who liked the slats.
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Originally posted by GRUNHERZ
Its 10 years, the slats were there the whole time.
Yes, but I was more refering to the war years when the pilots would have complained about the supposed ill effects of the slats in combat, and how unlikely it is that the slats would have been kept in the design if they did so.
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I also like my barn door,whose excellent mountings consist of rollers and tracks.
They are not imprevious to failiure though, and some of the people opening them don't like them at all...
What I am saying.
1.Probably most 109 pilots liked the slats, not all.
2. Slats like this are not imprevious to malfunction.
BTW, with slats opening as niklas sais only under high A.o.A., why have some pilots complained about them clonking in and out all the time? Surely, he means stall condition right?
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Originally posted by Angus
BTW, with slats opening as niklas sais only under high A.o.A., why have some pilots complained about them clonking in and out all the time? Surely, he means stall condition right?
I'd love to see you provide some evidence of that, even anectodal evidence.
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Hi Angus,
>"That kind of automatic slat has to be very well balanced and glide easily to have the desired effect. A slightly damaged automatic slat may open at higher A.o.A. than the normal opening one. This will cause assymetrical lift and unacceptable roll disturbances at high A.o.A."
"Moving parts can fail."
I consider that an irrelevant truism.
An aircraft has many more moving parts than the slats, and many of these moving parts fail with more serious consquences than the slats.
>So, mud, ice, and lack of lube, dents, holes, rust and so on come to mind.
Chewing out the crew chief comes to mind.
Do you have any evidence connecting poor maintenance to imperfect slat operation at all?
In my opinion you're attempting a molehill-to-mountain stunt here.
Regards,
Henning (HoHun)
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Dear HoHun.
This line was taken out of a commercial pilot aerodynamic teaching book. Call that irrelevant truism if you prefer.
Same to my statement of moving parts being able to fail. I would add to that as a prefix "external" in particular.
What comes to my mind of the possibilities I mentioned as highly likely, - and it actually has nothing to do with the crew chief- is ICE.
As for this:
"Do you have any evidence connecting poor maintenance to imperfect slat operation at all? "
Firstly I point my finger again to the quote pasted some three times into this thread, i.e:
" A slightly damaged automatic slat may open at higher A.o.A. than the normal opening one. This will cause assymetrical lift and unacceptable roll disturbances at high A.o.A"
I actually stumbled across this after this thread started. A pilot friend of mine left his book in my place (to my utmost pleasure), and for your knowledge, the 109 is never mentioned in the book.
So, that is where my connection POOR MAINTENANCE>IMPERFECT SLAT FUNCTION comes from.
And to the final:
"Do you have any evidence connecting poor maintenance to imperfect slat operation at all?"
I take that as regarding in particular the 109 or the LW. Otherwise I'd point again what is taught on aerodynamic courses.
So:
Answer is basically "NO" I don't. In fact I have at the moment, no evidence whatsoever that there was anything wrong with anything regarding the once mighty WW2's Luftwaffe's maintenance at all.
However, I'd consider it totally childish to assume that their maintenance would at all times have been perfect. Combat conditions are not always perfect, that is as simple as it gets.
But I'll dig up some stuff, will just take a wee bit.
(other channels than internet)
Regards
Angus
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Originally posted by Angus
BTW, with slats opening as niklas sais only under high A.o.A., why have some pilots complained about them clonking in and out all the time? Surely, he means stall condition right?
No. A stall situation would have been already too late.
Wing trials for the 109 without slats and washout instead showed a dangerous roll tendency, so they stayed with the slats.
And i wouldn´t give too much weight on pilots opinion. Let them fly the machines, but don´t expect the ultimative understanding why this or that feature was used on the machine.
I read of a pilot who described that they landed the 109 in service much harder than trained. Instead of coming in steep and letting it down on flaps and slats they came in flat at much higher speed. Maybe they didn´t like the slats because they didn´t use them, but that doesn´t mean that the slats weren´t an useful feature.
At the end no pilot can tell you how the 109 would have behaved at critical high AoA situations without slats because they were always "there". I´m sure after flying without slats they´d have been glad to have them back.
niklas
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Hi Angus,
>This line was taken out of a commercial pilot aerodynamic teaching book. Call that irrelevant truism if you prefer.
What is the relevance of the lines you quoted for the commercial pilot? His attention is drawn to the necessity of free and light movement of the slats so that he knows what to look for in a pre-flight check, and he is taught the symptons of imperfect slat operation so that he can properly report them to the ground crews.
What is the relevance of the lines you quoted for the design and tactical suitability of the Me 109? It's the attempt to apply it out of context which makes it an irrelevant truism - it just points out the possibility of a failure without giving the slightest information on the likelihood of that failure actually happening.
>Same to my statement of moving parts being able to fail. I would add to that as a prefix "external" in particular.
It was standard operating procedure for the Luftwaffe to push the slats into the closed position on parking the aircraft. De facto, the slats were an internal mechanism.
>>"Do you have any evidence connecting poor maintenance to imperfect slat operation at all?"
>Answer is basically "NO" I don't.
Well, that makes it all look like idle speculation, don't you think? :-)
Regards,
Henning (HoHun)
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Dear HoHun.
I have to give some feedback to your post. Sorry I couldn't sooner, - been tied up at work. (Surprizingly, mechanical stuff).
I shall begin with the top point a the subect of this thread:
"Do slats have negativce effect (like sudden "snaps") on 109Gs/la-5/7 in r/l if you pull the stick suddenly @ lo-turning speeds? I notice that slats dont always come out evenly and i think that's what's causing the 109G or la-7 to snap in AH2."
This is something I have stumbled across before in my reading and studying of WW2 aviation history.
I already posess some anecdotal and documented data about this.
I rather regard this as a thing to look into, rather than discarding it from the beginning, whatever the reason.
My thesis on this is that this could possibly be caused by malfunctioning slats (a war issue) rather than the slats being an imperfect design or aerodynamical princip.
My first look into this rather suggested that if there was a problem at all, it would be such an issue. You prefer to call that truism.
Anyway, any critic on the slats gets debated on this thread.
If I would draw a conclusion from your input, adding the input of Izzie, no less, the result would be that slats are imprevious to trouble at all,and all evidence poining elswhere is false or not properly backed up.
However there is still plenty of data around here to be looked into, so this thred will stay on for a bit I am afraid.
I do sense a certain evasiveness when it comes to a hard point, which I tested here. Your question:
"Do you have any evidence connecting poor maintenance to imperfect slat operation at all? "
My answer:
"I take that as regarding in particular the 109 or the LW. Otherwise I'd point again what is taught on aerodynamic courses.
So:
Answer is basically "NO" I don't. In fact I have at the moment, no evidence whatsoever that there was anything wrong with anything regarding the once mighty WW2's Luftwaffe's maintenance at all. "
Yet you choose to quote this as such with an answer as well:
">>"Do you have any evidence connecting poor maintenance to imperfect slat operation at all?"
>Answer is basically "NO" I don't.
Well, that makes it all look like idle speculation, don't you think? :-)
"
Dear HoHun, I am not sure where exactly I stepped on your tail to deserve this.
So here comes a test, a question for you:
"Do you have any evidence that the LW's maintenance work was always in perfect order throughout all of WW2"?
With a cut & paste permission, it's a YES or NO question. :D
Regards.
Angus.
P.S. I do have some stuff to add here soon. Just remembered also that there is a nice link regarding the positive side of fully working slats on the Spit I turning thread in this forum.
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Well in AH stuff does not break down or fail to operate unless its been subject to impact of some sort.
Hence unreliability is not modelled.
Slats used were very simple devices and many more components on an ac were prone to failure or/and mal adjustment.
The price paid for slats was the poor final departure characturistic.........
on some ac this was worth it on some not.
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Hi Angus,
>So here comes a test, a question for you:
>"Do you have any evidence that the LW's maintenance work was always in perfect order throughout all of WW2"?
>With a cut & paste permission, it's a YES or NO question. :D
Actually, It's a rethorical question.
And a von Däniken (http://en.wikipedia.org/wiki/Erich_von_D%E4niken)-style rethorical question, as it implies that in the absence of definite proof to the opposite, any speculation is valid.
However, the scientific approach has to follow von Ranke (http://en.wikipedia.org/wiki/Leopold_von_Ranke)'s definition that history can only be based on contemporary evidence.
Regards,
Henning (HoHun)
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Dear HoHun.
I rather suspected that you were somewhat a philosopher, now that theory is strengthened.
I haven't clicked on youe links yet. (Erich Von Daniken?). So this is not completely based on your feedback.
Well, I am disappointed that you did not answer my question, for it would not have been rethorical at all,- most of us know that the status of the LW late in WW2 could best be described as poor.
But hell, you choose to stick to Von Ranke's documentatism, clinch on it hard enough, and hardly anything can be proved.
Turning that around, I can still ask that question. Let's assume that the late-war-bombed-up Luftwaffe had troubles with keeping enough servicable aircraft in the air, - which I think even you agree that was the case.
So, can you definately proof that they still kept their aircraft in perfect condition?
Yes or No?
I have some more questions for you later ;)
Regards
Angus
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Angie, just for the record, late-war-bombed-up Luftwaffe fighter units had about 70-80% servicibilty rate.
I guess it`s only partially has to do with the devotion of them schwarze mann. The other half was the huge amount of brand new planes piled up in the storage centers. Why bother to repair, if you can just grab a new one?
OFF : I cannot imagine the consequences if the admin at HoHun`s workplace would ban the access to wikipedia. He`s a total addict of it. :aok ;)
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Hi Angus,
>I rather suspected that you were somewhat a philosopher, now that theory is strengthened.
You got that wrong. I'm somewhat of a scientist, as science is the only proven method to arrive at verifiable conclusions.
>Well, I am disappointed that you did not answer my question, for it would not have been rethorical at all
You got that wrong, too. If you don't recognize your question as rethorical, keep thinking about it until you do.
>Turning that around, I can still ask that question.
Just try to think up an answer that would satisfy von Ranke. Then you'll recognize why your question is deeply un-scientific.
>I have some more questions for you later ;)
They will have to wait until you've understood the folly of your first question.
Regards,
Henning (HoHun)
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Dear HoHun.
Now don't get too pompous mate.
My question is no less worthy than yours, and you also chose to answer mine in a most un-scientific way, clipping it in your quote.
After all, they are almost identical. Prove it was- prove it wasn't may be an issue, so maybe I should rephrase it to "What do you think".
But alas, yes or no may be too complicated.
And since you clinch on to Von Ranke, that's where you get, ain't gonna be yer buddy there.
Yet....
I still belive that there is some source to the myth of slats being able to cause negative effect at times, and that the explanation may possibly be a war-problem issue than the aerodynamic effect.
All ears.....
Regards
Angus
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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)
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with all the energy you two are putting into this moot argument you might as well focus on world peace. :eek:
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fly smart and smoothly and the slats dont snap out....
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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
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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)
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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.
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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 ?
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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?
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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.
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Exactly.
I have 2 barn doors running on roller tracks, right now, neither of them is ok.....:D
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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+
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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.
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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.
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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.
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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)
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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.....
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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... ;-)
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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
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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.
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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.
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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.
:D
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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.:rolleyes: :rofl :rofl It was perfectection personified.
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Yet, the 109 nerve seems to hurt a bit.
Watch that 109 nerve it is very sensative.
:(
Crumpp
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Originally posted by Crumpp
Watch that 109 nerve it is very sensative.
Lol. Do tell.
- oldman
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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)
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Gather all trolls to toss yer poop...
-C+
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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
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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
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So what was the difference between German and Russian slats and why were those better?
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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
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How were the 109 slats hinged.?
Anyway, after all, automatic slats seem to be anything but all the same, at least between planes.
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Originally posted by Angus
How were the 109 slats hinged.?
There was no hinges at all, the slots of the Bf109 moved just in/out. The early models before Bf 109F had a bit different design than later models.
gripen
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La slats (bad scan but better than nothing)
I don´t know whether the opening gap on the innerside is so good for the pressure effect of a slat ... (?)
(http://mitglied.lycos.de/luftwaffe1/sonstiges/lagg3slats.bmp)
niklas
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Its wonderful that yall are creating this wonderful discourse on the slats on the 109. Along with mentions of various other planes. That being said, I would like to point out a something that might be of slightly more importance to most of us on the BBS, that has only rarely even been mentioned in this thread, is how the slats perform in this simulation. Whatever the real life performance might have been, I'm sure it is not faithfully modelled here and now in AHII because quite frankly THEY SUCK. Whether its a bug, a screwed flight model........I have no idea, I never even knew slats existed until AHII came out and the 109 became more exciting than a roller coaster if you go too slow in a tight turn. In this sim they are not a way to prevent stalls, they CAUSE them. As one previous poster put it, give me a welder.........
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slats delay the effect of stalls, it doesnt stop them
if you ignore the stall buzzer and slats as a warning, then so be it.....
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The slays visual deployment is in my opinion a very good feature in AH2, I had seen it before in IL2.
You can see it, hear it, and feel it, and I rather feel it helps you to ride the stall in the 109.
I fly the 109 at times, and I think this is perhaps why I partly like it, - visual stall!
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Here (http://mig3.sovietwarplanes.com/lagg3/lg1/lg1-f2r.jpg) (Massimo Tessitoris LaGG-3 site (http://mig3.sovietwarplanes.com/lagg3/lagg3.html) ) is my favorite slot design; mechanically simple, mainteance free, no asyncronous opening and of course made by the Finns ;)
gripen
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So a slot lets the airflow through the wing in certain AoA to straighten turbulent airflow on top of wing?
(Notice slat/slot)
-C+
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Exactly.
The myth however states that automatic slats did not necessary need the high A.o.A. to deploy.
That's something I ain't figured out yet, - if, how and why?
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Got some input on my way to to this thread.
I'ts going to contain information, so PUNT ;)
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Ok, here goes.
Contacted a pilot (old wingco) who flew Phantom jets, which had automatic leading edge slats. He confirmed that the slats would deploy rather fast, giving very fast extra lift. The faster, the more.
He said he liked them very much, however he knew of instances where there were wing breakoffs/failiures because of slat effects, - radically increasing lift. (Phantom that is)
He confirmed that the faster the aircraft, the more was the feel of slats deploying.
He also said that the 109 could have their slats fixed shut easily, however that resulted in quite much higher landing speeds.
He did not know of any famous ace that had the slats fixed like all the time, but he was all ears!
He confirmed that the slats would have to be in absolutely perfect order to have the desired effect.
I will have more coming, digging deeper into the pond.
Regards
Angus
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Handlye Page And a German engineer obtained patents on slats at essentially the same time. It was a case of independent invention. They cross-licensed with each other.
-Blogs
Originally posted by 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.
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Originally posted by Overlag
slats delay the effect of stalls, it doesnt stop them
if you ignore the stall buzzer and slats as a warning, then so be it.....
That would be my fault as a pilot if I ignored the stall warning. Simple fact is, the horn goes off AFTER the slats come out. When whatever criteria HTC has set happens, the slats pop out and the stall horn goes off. Not the reverse.
Also, whoever posted that they are supposed to come out asynchronously, they dont. They come out at the same time on every model in AHII. Or at least they did before the newest patch (I havent tried them since patch 2) but Pyro didnt list anything to do with the 109 slats in his release notes.
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Hi Blogs,
>Handlye Page And a German engineer obtained patents on slats at essentially the same time. It was a case of independent invention. They cross-licensed with each other.
Actually, Gustav Lachmann got his first patent in 1917 and then was hired by Handley-Page, where he acquired a second patent in (I think) 1919. He was the inventor, but Handley-Page as his employer was the owner of the patent rights. I don't know what patents Handley-Page held before 1919, but everything seems to have been pretty typical business practice here. Aviation was an international business even back then.
Regards,
Henning (HoHun)
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IIRC MTT Ag paid license fees to Handley Page during war (via Switzerland or Spain or something).
gripen
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"Handley Page had acquired his own wind tunnel during the war [WWI], and among his early tests were trials of a wing with multiple narrow chordwise gaps which he hoped might delay the stall. It did not work. However, when a single narrow spanwise cut was tried the results looked more promising. Moving the slot close to the leading edge increased maximum lift by 25 percent, and refinement of the slot position and size soon raised this to a dramatic 50 percent. Patents were obtained and in march 1920 a D.H. 9 was tested with 'slats' fixed ahead of the wing leading edges to form the slot. This confirmed the wind tunnel results, the aircraft flying as slowly as 38 mph. Soon afterwards a young German pilot-engineer, Gustav Lachmann, chanced on a photograph of this D.H. 9 in an aviation magazine and saw its resemblance to the multi-slotted aerofoil he had attempted to patent early in 1918. He had stalled and crashed his aircraft the year before, and the idea of slots to delay the stall had occurred to him while recovering in the hospital. The German patent office was dubious, however, and rejected his application. Inspired by Handley Page's example, Lachmann now had his triple-slotted section tested at Gottingen; it increased lift by over 60 percent. With this confirmation his patent was not only granted, but it was backdated to February 1918, just prior to Handley Page's. HP went to Berlin to meet Lachmann. They got on well and agreed to pool their rights, and in return HP employed Lachmann as a consultant with a research grant at Gottingen, the start of their long collaboration."
Patrick Hassell, "Advances in Aerodynamics," in Philip Jarett, Biplane to Monoplane. London: Putnam Aeronautical, 1997
-Blogs
Originally posted by HoHun
Hi Blogs,
>Handlye Page And a German engineer obtained patents on slats at essentially the same time. It was a case of independent invention. They cross-licensed with each other.
Actually, Gustav Lachmann got his first patent in 1917 and then was hired by Handley-Page, where he acquired a second patent in (I think) 1919. He was the inventor, but Handley-Page as his employer was the owner of the patent rights. I don't know what patents Handley-Page held before 1919, but everything seems to have been pretty typical business practice here. Aviation was an international business even back then.
Regards,
Henning (HoHun)
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Time to revive this, for there is some data inbound.
I modestly earned my place on HoHUn's mighty ignore list for the lack of evidence of the possible downside of automatic slats.
Here is the sentence from the judge.
"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. "
THat pilot he refers to is Gunther Rall. I replied after having a conversation with Rall, - which is of course not documented.
However, I did not see my reply, but, presto, found it in his new book, in German, MEIN FLUGBUCH, look at website meinflugbuch.de.
It's in German, - here follows my translation. p.45, Rall has just shot down a Curtiss and is hit by another one. He takes a vicious turn to evade. What happens?
"...I turn the Messerchmitt to get out of the line of fire. My turn is so sharp and steep that the outboard slat jumps out and the aircraft whips out of the turn, - a betrayal of the Messerchmitt, which in this war I am to curse many more times."
I can post this in German later on if needed.
I also have yet another report on the 109's quirks, which touches the subject of slats slightly. Next post.
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it stalled cos he turned too hard, not cos the slat came out. slats are great, they dont STOP stalls, just increase the AOA you can use, but they arnt miracle (spelling?) workers
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I think he was only posting to provide proof the statement had been made, not to make a claim one way or the other on the performance of the 109 slats.
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Saw this thread late, but I have something to add. My Dad was an A4 Skyhawk pilot, the A4 had simple mechanical automatic slats exactly like the AH planes. He said that they DID open asymetricly under the right conditions and it would cause (sometimes severe) instability until the other one popped out. While the Blue Angels flew the A4 Skyhawk they had the slats fixed shut so they would not deploy on one wing and not the other. At 36" separation you cant afford to have that kind of destabilizing event.
How does this correspond to AH? I made a film of me flying a 109 and flew around making the slats open and close, both in level flight evenly, and in different attitudes so that they opened unevenly. Dad said that was exactly how they were supposed to act, and he was quite impressed with that kind of detail.
I can not tell you anything about 109's slats in real life, if their pilots liked or loathed them, if they were or were not wired shut (and dont really care), but I can tell you that the slats in AH work exactly as they did in RL.
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Cool! Thanks for sharing Grits!
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If the slats open assymetrically, that is because it just happens that one wing has less lift available at high angle of attack. Now if there wouldn`t be slats, what would likely follow is an extremely case of instability, a snap roll towards the stalling wing as the different lift vectors act on the airplane. See spitfire, and esp. the 190/Mustang stall characteristics.. This is also more likely to happen if the pilot doesn`t keep the ball centered in the turn. Now if he has slats, then they would open on the lower lift wing, restoring lift, but as the slats are open in one wing and not on the other, there will be some difference, but not nearly as violate as if one wing would suddenly loose all lift due to flow separation, what the slats would prevent (or more like delay) happening.
And yes, slats are no magic wands for a stall free enviroment. The stall will just occure later with them.
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"I also have yet another report on the 109's quirks"
I can hardly wait...
:)
-C+
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main problem with AH slats is they are either open or closed which means 100% or 0% effect, causing the issues we have.
in real life they came out smoothly i would have thought?
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"in real life they came out smoothly i would have thought?"
That is how they are modelled in IL2 but in stories of 109's slats they are always described as coming out at once with a "clunk" sound being heard even inside cockpit. The Russian planes had a different hinge system than 109s, so those might have worked differently as the axial torque of the hinge does not hinder the movement of slat as it MAY do in 109. Dunno for sure because I do not have an accurate drawing of 109 slats.
Anyway, as their deployment happens by sufficient air entering the underside gap of the slat I'd imagine that flow to force the slat open at once. Maybe you could get them to move into closed position slowly by very slight movements in nonturbulent air but I think their principle of function suggests they always bang open unless regulated somehow (but that would be once again a potential place for mechanical failure).
-C+
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Anyway, as their deployment happens by sufficient air entering the underside gap of the slat I'd imagine that flow to force the slat open at once.
Think you have this wrong charge. The slats were held closed by air pressure and there was no gap until the slat opened.
How much AoA is there when the a/c is landing. It is said that the slats came out during the turn to final. (the a/c is basically level, so 0* AoA.)
We need Straiga to come and tell us how slats work, him being an aviation expert and all. :aok
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Originally posted by Overlag
in real life they came out smoothly i would have thought?
Well, I cant say for the WWII planes, but Dad says on the A4 they pop open, and they are either open or shut, and its a very sudden movement like in AH. He said you cant hear them, but you can feel them.
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"Think you have this wrong charge. The slats were held closed by air pressure and there was no gap until the slat opened. "
I can't seem to confirm this Milo. In some pictures I thought I saw the gap but in some pictures it is totally invisible. If there is no gap I don't understand how they can be forced open against the airstream?
In "http://109lair.hobbyvista.com" there are very detailed pictures of slats but they gave me no evidence if there really was a gap on the underside.
edit: Bf 109G-6 "MT-452" W.Nr. 165227 has some pictures where a very slight gap is visible and a bigger gap in the vertical portion on the outer end of slat. Not a big gap, though...
-C+
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Well, Rall uses the expressions "jump" or "pop" or "Snap".
And note, that he mentions that this is something he would curse many times.
However, when I asked him whether he would have preferred no slats, he said they were necessary, - without them the landing speed would have been much to high.
So, it was the slats interfering in a rough turn he did not like.
Bear in mind that he flew many allied planes as well, including the P51 and the Spitfire.
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Angus, if I would go to same lengths of reading what I want to see I'd say that because he was a "sniper" ie. could shoot accurately from very long distances he didn't like the slats because while tracking the target he many times gently pulled over the threshold level when the slats suddenly popped open, ruining his aim -from long range.
In banking turns the slats may come out asymmetrically but having disastrous effects on handling? Of course you can pull an evasive in 109 which would come out as a stall and cannot be saved even by the slats and that would be even easier in a Spit.
As i see it that comment on losing control in sudden evasive is just him blaming somebody else than himself.
-C+
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Originally posted by Angus
So, it was the slats interfering in a rough turn he did not like.
Bear in mind that he flew many allied planes as well, including the P51 and the Spitfire.
Maybe he would prefer a violent 180 degree flick roll instead of slats in rough turns, a la Mustang/Spitfire? I doubt.
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Slats are sucked open due to a combination of speed and angle of attitude (incidence) and held open by negative pressure whilst the combination of incidence and speed are maintained.
They are balanced to open rapidly and positively.
Their task is to inject a stable boundary layer of air (thru the slot created)over the upper surface of the wing which prevents loss of air flow in near (or otherwise) stall conditions.
Their primary disadvantage is that the final onset of stall (once the incidence is so high as to defeat the slat) is very rapid.................... hence if your ac was to loose lift over only one wing due to the manouvre under consideration then the subsequent loss of lift from that wing could be seen as violent compered to other wings ....like a spitfire for instance.
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Nice info Tilt thx.
I don't really see why you people are talking about Spitfire when regarding slat behaviour? P51 has a similar shaped wing as the 109 except for profile, but he Spit does not. I have never read of Spitfires flip stalling 180 deg. AFAIK Spitfires leading edge is curved to even out the pressure build-up on the leading edge aiming for least drag. This in turn for its part causes the whole wing to lose its lift at the same time if max AoA is exceeded. Washout helps by giving warning of the stall and by delaying the stall but when elliptic wing stalls it is "total". Tapered wing stalls more gently but in turn produces more drag. AFAIK that is...
-C+
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I thought spit wings were slightly twisted to soften the onset of stall which also gave an audible sound near the wing roots during their departure.
Could the reference to "flick" departures be limited to high speed stalls.
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Ok, here goes. From Charge
"Angus, if I would go to same lengths of reading what I want to see I'd say that because he was a "sniper" ie. could shoot accurately from very long distances he didn't like the slats because while tracking the target he many times gently pulled over the threshold level when the slats suddenly popped open, ruining his aim -from long range. "
A former LW wingco who worked with Rall in the Bundesluftwaffe (RET, working with history now!) told me that he considered Rall to have been the finest shot of the old LW. Better than Marseille.
(Rall considers Marseille to have been the best, but that's just being modest I think.)
Anyway, Rall excelled at deflection shooting, while Marseille was famous for plonking around at no speed and shooting his foes right in the eye at no range. Using the slats there BTW, but that's enough for a whole thread.
So, yes, you have a point, Rall complained about the slats throwing one off the aim. He said he preferred the slats for anything but combat basically.
Then Tilt came along with this:
"Their primary disadvantage is that the final onset of stall (once the incidence is so high as to defeat the slat) is very rapid.................... hence if your ac was to loose lift over only one wing due to the manouvre under consideration then the subsequent loss of lift from that wing could be seen as violent compered to other wings ....like a spitfire for instance."
Very nice, I could never have put this so well. The slat plonks out quite swiftly, changing the game, and at high speed a lot will happen before the pilot has the chance to respond to it. I belive that must be what it's all about (look at the question in the start of the thread), - but still......
Now on to quirks.
What I so far found was the slats need to be well balanced and glide easily to have the required effect.
Recently I aquired a document which I may quote. Will post in less than an hour or so. It basically states that it is necessary for the 109 to be "flown in" properly for the slats needed to be set correctly.
Ok, I made some folks mad on this thread by suggesting that the negative effect of slats could possibly have their roots in damage or bad cirkumstances. Anyway, I honestly am a tad baffled now, for both explanations seem to be rather valid.
Ok, will post as soon as I dig up that doc and type from it.
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Originally posted by Angus
The slat plonks out quite swiftly, changing the game, and at high speed a lot will happen before the pilot has the chance to respond to it. I belive that must be what it's all about (look at the question in the start of the thread), - but still......
If you look at the CL curve for an La7 (I dont know about a 109) it is smooth across the slat opening point.
Slats do little to actually add lift they simply preserve laminar air flow over the upper wing as the angle of incidence increases beyod the wings natural departure point. However when they are no longer able to sustain the laminar flow then the characturistic of departure is sudden.
Handling is not changed as they "plonk out" it is drastically changed as they are defeated.
Notem.
Stated above that slats do little to add lift. Of course as they allow the wing to operate at higher levels of incidence then they of course allow the wing to generate more lift thru this increased angle. They do not add lift due to their extension alone as a product of increased wing area or such like.
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THX in advance :)
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"What I so far found was the slats need to be well balanced and glide easily to have the required effect. "
I agree. If you find out that they had problems with the slat mechanism it would be interesting info. If they changed the mechanism from 109E to 109F there probably was a good reason, which is not documented anywhere for some reason. Maybe the first version really was prone to jam because of dirt or icing and the second version installed in 109F/G cured some or all of this, but then again the Russians chose to use a different kind of hinge?
OTOH it is interesting that the German pilots rarely even say anything about slats in their books just as if they didn't even notice them in flight. It was either that they were so smooth in operation or that they usually flew in the fast part of flight envelope so the slats usually didn't deploy in any part during flight.
-C+
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But, you can stall at any speed basically.
Now on to the dirt and ice.
I had mentioned that dirt and ice issue before, whith little popularity actually. But it seems rather logical, for the LW was having a really diffucult time in their retreat from the eastern front particularly, sometimes staying only for a day on a temporary airfield.
There is something about the hinges somewhere above in this thread, but overall it is a very simple design.
Still bothers me why they are not used in modern light aircraft if they were as some here have claimed, almost perfect and totally simple.
Just a Cessna 172 or a Cherokee will stall at 60 kts, - those are little aircraft with mere 150-200 hp or so. If slats were that great why are they not used on small aircraft today?
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Originally posted by Angus
Still bothers me why they are not used in modern light aircraft if they were as some here have claimed, almost perfect and totally simple.
Just a Cessna 172 or a Cherokee will stall at 60 kts, - those are little aircraft with mere 150-200 hp or so. If slats were that great why are they not used on small aircraft today?
why would you need slats on a Cessna? not as if you are pulling high G turns is it?
they are used on modern fighter jets, they are just much more advanced
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Originally posted by Overlag
why would you need slats on a Cessna? not as if you are pulling high G turns is it?
they are used on modern fighter jets, they are just much more advanced
Why would the Stringbag need slats, and it did have them, for it did not pull high G turns. The Storch had them as well. Made for a much lower landing speed, it did.
Angus, I would speculate it would be because of safety > if one came out and the other didn't, the civvy pilot would not be able to correct in time so close to the ground.
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(http://www.military.cz/usa/air/war/other/l1/l1mus.jpg)
(http://www.skyshops.org/701%20bin/701whitelandstep22.jpg)
(http://www.global-air.com/global/planes/g05116_2.jpg)
(http://www.zenithair.com/stolch801/pic-gecx/899-j.jpg)
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Originally posted by MiloMorai
Angus, I would speculate it would be because of safety > if one came out and the other didn't, the civvy pilot would not be able to correct in time so close to the ground.
Slats do not add lift. If only one slat pops out nothing happens unless the pilot is unaware of the situation and stalls the other wing by continuing to lower speed/tighten turn.
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Originally posted by Angus
Still bothers me why they are not used in modern light aircraft if they were as some here have claimed, almost perfect and totally simple.
Just a Cessna 172 or a Cherokee will stall at 60 kts, - those are little aircraft with mere 150-200 hp or so. If slats were that great why are they not used on small aircraft today?
For the simple reason: modern Cessnas are pieces of **** first, aeroplanes second. Every measure is taken by the maker to make it as cheap as possible and sell it at highest price they dare to ask.
As fas as stalling at 60 kts goes, Typhoon stalls at some 65 mph IAS at light loadings...
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Hehe. true. Build an aircraft with so little weight that still needs several hundred yards of runway. And Cessna stalls like a *****!
Same goes with the Cherokee, - needs a long way to get airborne, - however gentle to no departure charactericstics.
(Been in them when deliberatly being brutally stalled)
Anyway, Scholzie, nice collection. Do you have the types of those?
And again, something to debate on. What is the world without a debate anyway.....
"Slats do not add lift. If only one slat pops out nothing happens unless the pilot is unaware of the situation and stalls the other wing by continuing to lower speed/tighten turn."
Well, they lower the stall speed, and correct a stall about-to-happen very quickly. Now with both slats operating, before the other wing stalls, the slat there should also deploy. The first wing to stall should (in a turn for instance) be the outboard wing. So I think you have it wrong there.
The outboard wing stalls before, and then the stall is quite cruel. However, with no slats the stall would have occured before anyway.
In a ROUGH turn as Rall describes it, this can happen differently, for this is very quick. The slat jumps out and corrects the beginning stall procedure so viciously that the aircraft flicks out of the turn. This is how he describes this anyway, and boy, that guy made many a rough turn!
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What are you babbling about? The slats deploy before the wings stall, with a safe margin too. Unless the pilot doesn't notice that only one slat has deployed there is no problem. All he have to do is keep the plane fast enough so the wing doesn't stall.
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the main purpose of slats is to make the aileron section stall later than the inner wing section, and nothing else. So you can keep aileron / airplane control.
In rough turns the effect may come to late so the aircraft stalls before you can benefit of the slats. Or they pulled the aircraft so much that it get stalled in the outer section even with slat effect. I wouldn´t give too much on pilots opinion why the aircraft did spin out of a turn. Fix the slats in closed position and let them fly it again, i´d like to hear their opinion now!
Cessnas have to be cheap. And when takeoff distance is always longer than landing distance due to the low power output and a fixed prop with poor efficiency at takeoff, there´s absolutly no necessarity to lower landing speed even more. Imo it´s low enough. Do there many landing accidents happen with Cessnas?
niklas
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As for the types, dunno exactly. The top one looks like a Curtis design. The red and blue one is French I believe and the two others are Czech.
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Btw. didn't mean to be rude Angus. Sorry.
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Hey Scholzie, NP mate :)
As for the Pilots opinion, I asked Rall whether he heard of any pilots fixing their slats. He said "NO"
I asked him if he would rather not have had them, he said they were necessary, without them the landing speed would have been too high. (?!)
He added "But I did not like them in combat"
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Oh, and for Niklas:
"Cessnas have to be cheap. And when takeoff distance is always longer than landing distance due to the low power output and a fixed prop with poor efficiency at takeoff, there´s absolutly no necessarity to lower landing speed even more. Imo it´s low enough. Do there many landing accidents happen with Cessnas? "
I wonder, do you fly?
Anyway, those aircraft piss me off a bit, for you have something rather light in your hands with very little power, It stalls at roughly the same speed as a 3 ton WW2 fighter!!!
I live beside a countryside runway, some couple of years back a Piper used all 800 m. of runway without getting airborne. Well, it was actually a pilots mistake, but there was not much margin for cancelling anyway.
I have to disagree with you about the landing speed. Just 10-20 kts make a heck of a difference. Can't remember the exact figure, but an educated-from-memory guess is that the difference between a 50 kts and a 70 kts crash is a double one in fatality.
So, those slats at low speed are really worth their weight!
Sometime ago I posted a pic of a Dornier private aircraft, post war. I think it is a 6 seater. It has slats (fixed perhaps?). It stalls at 27 kts! Now that is something for security.!!
I'll try to find a pic of it to post, - one beautiful bird in LW colours.
(BTW, the owner is an old skipper from the DC-4 and DC-6 days. He survived from smashing into a glacier on full cruise in 1954 or something near that)
So, goodnight gents.
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Imo a very slow aircraft is more vulnerable to wind turbulences than a faster one, because realtion wind speed to aircraft travel speed becomes higher. And imo wind effects are the main cause for accidents during landings. So imo it´s not too desirable to land at very low speeds. For example, when front wind of 30mph suddenly becomes zero and your landing speed is 60mph, you lose suddenly 75% of lift. When you land at 90mph you lose only ~55% of lift. The same principle applies generally to the effectiveness of the control surfaces.
i did fly around with a Cessna once, got also the control. We did some manoevers, kind of wingovers and also tried to stall it. Absolutly no problem and very gentle at low speeds
niklas
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You have this the wrong way around.
On a short field especially, low stalling speed is worth a lot.
Low landing speed is good, that's why pilots land at almost as low speed as possible.
Do you fly?
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You don´t understand my logic.
The landing distance of the airfields we talk about is always long enough because takeoff distance is the critical distance. An airfield that is so short that you can land but not takeoff is useless, agreed?
A fw-190 jabo pilot wrote in his memories that his squadron leader forgot to use flaps during landing. He overshot and disappeared in a fireball. THIS is a short airfield, where no flaps make you overshoot the runway! Well those powerful ww2 fighter maybe needed less takeoff distance than landing distance (have to check sources). For Cessnas it´s inverted.
Furthermore i´m sure that airfields are only cleared for special aircraft types if they offer plenty of safety distance, except we talk about some lost places in the rain forest...
In normal cases you want to land as slow as possible, nevertheless i´m convinced that a very low landing speed is more critical during gust wind than a reasonable high one. I don´t want to say that Cessnas should land with 150mph! Nevertheless: The higher your speed is compared to wind speed the more safe you are against changes in wind speed, logically!
And once more, the landing speed of a Cessna is already so low AND the approx. rectangular wing design let the outer wing section naturally flies at a lower lift coefficient than the inner section (see pic) that slats are not necessary at all!
(http://www.mitglied.lycos.de/luftwaffe1/flugmechanik/Auftriebsverteilung.gif)
niklas
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Not quite agreeing although I see your point.
Cessna's, no matter what you say, don't stall too well. They dip a wing, and there is no problem provoking a spin.
A Cherokee is however the opposite, it just plonks down at the stall.
Landing distance for those little ones is if anything somewhat lower than takeoff distance, it quickly turns around with some more speed and power.
If higher landing speed is safer, a lower stalling speed is still positive. You want the stalling speed to be lower than your landing speed, yes?
If not, what are slats good for anyway? I asked Rall whether he would have had his slats shut for he did not like them in combat, and he said NO, without them the 109's landing speed would have been unacceptably high.
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Originally posted by Angus
If not, what are slats good for anyway? I asked Rall whether he would have had his slats shut for he did not like them in combat, and he said NO, without them the 109's landing speed would have been unacceptably high.
If Rall thinks the only reason the slats were there on the 109 and others to improve landing characteristics, then he is simply wrong. He is no engineer after all, just a pilot, and probably won`t go into a lenghty in detailed discussion lasting hours just on slats when somebody asks the same question the 1345th time..
The moral of the story ? Rall didn`t like slats, while others like Stiegler did like them. Any progress made? No. Unless one consider Rall the one and only source for everything, like angie does.
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Originally posted by Angus
[BCessna's, no matter what you say, don't stall too well. They dip a wing, and there is no problem provoking a spin.
A Cherokee is however the opposite, it just plonks down at the stall. [/B]
I was flying in a Cessna where the pilot provoked a stall and it was very gentle and controllable. He said however that he wouldn´t do it with a low wing design (Cherokee?). So i can´t follow your points.
In case of a rectangular wing slats don´t really delay the stall. Stall happens there in the inner wing section first see pic. Assuming slats would give you even more angles in the outer section: What´s worth a stalled situation where you drop like a stone because lift has broken down completly in the innersection, but you still can keep the least amount of control in the outer section? It´s not desirable that pilots enter such a situation, if the airplane begins to shake they should know to drop the nose rather than pulling even more.
Full wing slats would be something different. The fieseler storch repliqua i saw at an airshow did almost fly like a heli.
Does the Cessna has some kind of boundary layer fences on the top? Way simpler, also very effective. Not as good as slats though.
niklas
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Oh, the points:
"I was flying in a Cessna where the pilot provoked a stall and it was very gentle and controllable. He said however that he wouldn´t do it with a low wing design (Cherokee?). So i can´t follow your points. "
My point is that the i.e. C172 or even the 152 will with a power off stall dip a wing and enter a spin.
The Piper will just dip itself. Been at it some times, the thing is rather unwilling to enter a spin at all. In one case it just dropped, in another, which was a rather rough one, it just fell nose down with hardly any bank at all, then recovered quite quickly.
The person in the back seat was not buckled and not aware of this, - she hit the roof quite heavily!
BTW, in my rides on those, we always land on the BUZZ.
I'd love to land with 10-20 kts yet to go to the buzz if you see what I mean.
That Dornier I mentioned is a beauty. I'm trying to find an online picture of it. You'll love it :)
Stalls at 27 kts.
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Here is that pretty Dornier I was referring to :)
(http://www.islandia.is/aeroweb/islenski_flugvefurinn/mulakot/images/mul01_1493m-)
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Oh, no.
Try this link:
[url]http://www.islandia.is/aeroweb/islenski_flugvefurinn/mulakot
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In Angus's defence I belive I saw the same video of Rall maybe it was one of the other Aces saying they didnt like the wing slats.Ill have to go back and watch it again.I thought he said somethin about them being upredictable as to when they deployed.May have been Wings Of the Luftwaffe me109 show.Also on Wings Of The Luftwaffe 262 episode they show a mechaninc with a pair of plyers adjusting a set of leading edge slats so they would work properly.
Pipz
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I Flew an archer to get my PPL PA-28 and it had a placard that said that under no circumstances would spin or other type of acrobatic maneuver could be performed,and for good reason since the airplane was very touchy,and whewn it was power off it fell like a ton of tiny bricks .
The cessna 172 that I flew 3 times later on I did several power off and power on stalls, in the power on however where in the archer you would stall in teh C172 we almost went vertical and the damned thing didn't stall :D When it did it went into take off speed inmidietly.
If and when I fly again somewhere in the future( God I hope so) I'd like to go back flying Cessnas compared to an Archer they're friggin awesome :D
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My quote from Rall does not come from a video.
I was chatting with him :D
(not joking actually)
But I have seen him say something similar on video, trying to get that copied into MPEG. That is from the Duxford BoB anniversary year 2000.
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Alright. I know I'm probably beating a dead horse here, and lots of folks wont thank me for digging this thread back up. It seemed to light a few tempers. However, a few weeks ago I was digging in one of the local used book stores and came upon "The Illustrated Directory of Fighters" by Mike Spick. I own a few of his books, and they seem very well written and researched. I have heard more than one person praise his books. So I doubt he would make flat out statements about things if there was a doubt.
In the quest for performance, the Bf 109 was the smallest and lightest airframe that could be wrapped around the most powerful engine then under development. It was angular, with squared-off wingtips and a rectanglular braced tailplane. The canopy enclosing the cockpit was of heavy metal framing, side-hinged. This made it rather unpopular with pilots, many of whom preferred the open cockpit of the He112, which had a very similar performance.
Wing loading was comparable with the Spitfire and Hurricane, but, with an eye to future weight increases, automatic slats were fitted to the outboard sections of the wing leading edge, with large slotted flaps to the trailing edge, supplemented by slotted ailerons which drooped when the flaps were lowered.
(Some parts here about the narrow track landing gear).
The test flight programme uncovered problems with wing flutter, tail buffet, a tendency to drop the port wing before touchdown, a strong tendency to swing on takeoff and landing, leading edge slat malfunctions, and the inherently weak undercarriage. Despite these faults, the Bf 109 was selected as the future Luftwaffe fighter, and for the most part its pilots had to learn to live with its shortcomings.
(Several paragraphs here on the line from prototypes up to the Emil).
The Emil handled well in the low- and mid-speed range, although above 300mph (483kph) the controls became progressively heavier; the ailerons in particular becoming almost immovable at 400mph (644kph). During hard manoeuvering the leading edge slats tended to open asymmetrically, which did nothing for precision gun tracking. In combat, its greatest advantage was fuel-injection which allowed it to perform negative-g manoeuvers without loss of power. However, it remained touchy on takeoff and landing, and the accident rate, both in training units and operational formations, was horrendous. Bf 109 ace Werner Molders tested a captured Spitfire and a Hurricane in 1940; he described them as childishly simple to fly, unwittingly making an adverse comparison with the Emil.
(In all the rest of the article, I note only one reference to changes in the design)
(The 109F) .............. had a much sleeker nose with a larger spinner. The wings were redesigned, with rounded tips, shallower underwing radiators, Frise-type aileron surfaces and plain flaps. The bracing struts to the tailplane vanished, and the tailwheel was made retractable.
(Some bits I left out here on 109F armament).
Performance was given priority over manoeuverability. Creeping weight growth had set in, and while greater engine power allied to a cleaner aeroydynamic design gave the Franz a far better performance than the Emil, increased wing loading (about 40 percent greater than that of the Bf 109 prototype), adversely affected turn radius. This last was not particularly important so long as the Messerschmitt pilots stuck to dive and zoom tactics, and avoided mixing it.
I attempted to note in ( ) when I skipped an area I didnt feel at all weighed on the subject at hand, and what was in the skipped over material. I wanted it to be as contiguous as possible.
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Spick... :rolleyes:
-C+
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Originally posted by Charge
Spick... :rolleyes:
-C+
Thanks for the intelligent input. If you know of a reason to disregard his writing then say so, because I'd truly like to know. I know alot of people who have put alot of stock in his writing for many years. You are the first one who has had anything bad to say, and you just make the childish rolleyes thingie instead of commenting? Several times in this thread documentation was asked for, I found documentation and posted it. If you can show me it's not reliable, then it has alot of bearing on what I posted, since he doesnt show any of his sources.
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The horse is alive....and kicking
Interesting about the slats actually.
It lives...I hope
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Like I've said before, in 10 years of Bf109 development you'd think they would get rid of the slats if they were no good.
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Something that made me curious, on the Emil wings, the book stated the ailerons would droop when flaps were deployed. The picture shows the flaps themselves in two separate parts, the section closest to the fuselage having another piece that sticks down further. I cant see much "droop" to the ailerons, but the angle really isnt right for it either. I most certainly do not see any change from level in the ailerons of an F model on the next page that has flaps deployed. Wouldnt affecting the ailerons with the flaps cause a reduction in manuverability?
As for whether or not they would have changed the slats if they had problems................why would they? It was an integral part of the design. They never tried to find a way to increase the landing gear track. That was a problem (just like the slats) from the prototype stage. Matter of fact, after the F model, they made no significant structural changes other than what would be necessary to fit the larger engines in place and some changes to accomodate changes in armament. I'm not trying to make a case either way on the slat issue, I'm just making the point that it could very well have been a problem that plagued them all the way through to the final plane built in postwar Spain. Who knows? The book did say it only happened under "hard maneouvering" and did not say that it caused accidents or anything else other than it made shooting more difficult. Then again, maybe they fixed it with the wing changes in the F model. Again, someone asked for documentation in this thread, I found a mention of it in this book I picked up, so I shared what I found. Some of you guys have forgotten more about WWII fighters than I'll ever know, this just happens to be a thread I'm interested in because I like 109s.
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Why would they? ... They are Germans. If it isn't mechanical perfection they will work on it till the Sun explodes to get it right.
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Sorry SOA2. To explain a bit: To me M.Spick uses such expressions in all his writing that gives out his obvious bias.
On subject: Wing loading was not comparable to Spitfire of Hurricane but pretty much higher on 109. There were other qualities that made 109 competitive with those planes.
All those test flight problems could be overcome with careful handling in take-off and landing, but despite that it was a difficult ride for rookies.
I don't know what he means by precision gun-tracking in hard maneuvers? I don't think those words belong in the same sentence. As stated before the transition of flight states COULD cause asymmetrical opening of slats but hard maneuvers certainly forced them open quite evenly.
An "easy to fly" aircraft is not always the best fighter. I think Mölders referred mostly to their qualities which were possible by their low wing loading ie. very easy to land and take-off.
I'm not sure if the landing accidents were "horrendous", but surely higher than those of Spit and Hurricane.
Some anecdotal sources state that the F was in fact better turner than the E. Once again it is not simply a matter of wingloading as he likes to bring up (quess why ;-)). AFAIK its turn rate was better than that of E. Plus it was considered the best variant of 109s by many. The G6 was probably the worst model after which more engine power could compensate worsened handling caused by weight escalation.
On aileron drooping: actually the drooping effect changes the profile of the whole wing from tip to root to suite better conditions required by slow flight. Without that droop the 109 would be a potential "tip staller" and that would be very bad as root stall is more controllable and you do not want to tip stall upon landing in low level. (You might want to check the mysterious Buchon accident which happened to Mark Hanna). Anyway, nearly all modern aircraft use similar system nowadays.
On landing gear: They did change it quite a bit, strengthened and wider track, more forward rake and bigger tyres for bad runways, but they could not change the most crucial thing: they were center line (just as in Spitfire which had even narrower track and even softer tyres...)
Thanks for yor input StaroA2 and I'm sorry for my initial attitude to your writing. :(
-C+
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Originally posted by Charge
Sorry SOA2. To explain a bit: To me M.Spick uses such expressions in all his writing that gives out his obvious bias.
I can see where one could get that opinion. I dont know one way or the other. In his book I have about the Luftwaffe aces, he seems very objective. But then I've only read 4 or 5 of his books, including this one which is as much illustration as it is record.
On subject: Wing loading was not comparable to Spitfire of Hurricane but pretty much higher on 109. There were other qualities that made 109 competitive with those planes.
I believe he was only referring to the prototype here. Its not completely clear. His transition from pure prototype discussion to Emil is not completely clear. I'm sure that by the time they reaced the E model 109 the wing loading was much higher than originally.
All those test flight problems could be overcome with careful handling in take-off and landing, but despite that it was a difficult ride for rookies.
I don't know what he means by precision gun-tracking in hard maneuvers? I don't think those words belong in the same sentence. As stated before the transition of flight states COULD cause asymmetrical opening of slats but hard maneuvers certainly forced them open quite evenly.
Here, to me, he is saying that if the pilot were to make a harsh maneuver (not just a high G turn or other "normal" fighter plane movements), say in the effort to gain a quick snapshot, the slats could come out asymmetically and throw off the aim. I can see instances where the G load might be different momentarily between the wings and perhaps cause one to have some added impetus to speed it to full deployment. Even if only that way for a second, it could throw your aim off.
An "easy to fly" aircraft is not always the best fighter. I think Mölders referred mostly to their qualities which were possible by their low wing loading ie. very easy to land and take-off.
I would agree with that. I am limited in experience to Ultralights, hoping to expand that very soon to Sport class but thats still nowhere near even the complexity of a full size airplane, let alone the complexity of even a WWII technology fighter plane. "Easy to fly" usually means compromise; and while everything has to be a compromise, I would think a fighter design would try to have as few as possible.
I'm not sure if the landing accidents were "horrendous", but surely higher than those of Spit and Hurricane.
I have no evidence of that either way, but I have read in more than one source that the narrow landing gear, coupled with the high torque and the relatively light frame could cause inexperienced pilots to flip the plane over on its back during takeoff or landing. It wouldnt surprise me. But then, its just my opinion based on what I've read. If there were inaccuracies or bias in what I read, it would show in my opinions. I dont know how to verify it as I have no access to official records.
Some anecdotal sources state that the F was in fact better turner than the E. Once again it is not simply a matter of wingloading as he likes to bring up (quess why ;-)). AFAIK its turn rate was better than that of E. Plus it was considered the best variant of 109s by many. The G6 was probably the worst model after which more engine power could compensate worsened handling caused by weight escalation.
I have read many times how pilots preferred the F-4 over all other models of the plane. Some liked one aspect or another of different models later on, but all pilots who flew the Bf 109 F-4 seem to have had a lasting impression of quality. I believe it was Galland who was quoted as calling it "an artist's" plane.
On aileron drooping: actually the drooping effect changes the profile of the whole wing from tip to root to suite better conditions required by slow flight. Without that droop the 109 would be a potential "tip staller" and that would be very bad as root stall is more controllable and you do not want to tip stall upon landing in low level. (You might want to check the mysterious Buchon accident which happened to Mark Hanna). Anyway, nearly all modern aircraft use similar system nowadays.
Now that you have mentioned that, I remember seeing something like that when flying on commercial planes. It didnt connect until you said that. Duh. I find it ironic though, that "tip stall" is exactly what everyone who flys the AH version complains of.
On landing gear: They did change it quite a bit, strengthened and wider track, more forward rake and bigger tyres for bad runways, but they could not change the most crucial thing: they were center line (just as in Spitfire which had even narrower track and even softer tyres...)
Thanks for yor input StaroA2 and I'm sorry for my initial attitude to your writing. :(
-C+
No problem, I wasnt in the best of moods myself that day. I didnt realize they did actually upgrade the landing gear. I dont think that was anything I read that made me believe that way, probably just assumption since I have always read about the narrow track being a problem. Thanks for the response, much appreciated.
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Rall's impression on the 109F was
"Lovely, - highly maneuverable. Absolutely the best model. The 109G was overloaded"
On the slats (once again) he said that they were necessary for the landing in particular, otherwise the landing speed would have been too high. However he did not prefer them in combat, for they would be snapping and throwing the plane around. Being asked, he said that in a rough turn, the outboard slat would jump out and completely snap the aircraft (say left to right).
Asked whether he knew any that had the slats fixed, his answer was a NO.
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Well well, new here. loads of "slat" data. I do recall a Finnish pilot saying that they did not affect steering. Didn't mention whether aim was affected. Will try & find this quote.
Spit wing was designed by Heinkel I have read. Before war there was quite a bit of sharing. Handley page slats etc.
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Welcome, Agent 009. :)
Check out the pilot comments on slats in the "Messerschmitt 109 - myths, facts and the view from the cockpit" (http://www.virtualpilots.fi/feature/articles/109myths/#slats) article.
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Nice article. And a VERY nice webside :)
I see that some of my speculations booed on further up in this thread are brought in it.
Like this:
"We haven't yet seen a single reliable account about pilots wiring the Bf 109's slats shut in the western front. Only rumours and claims. In Africa this might have happened - primary reason why to do it was the dusty conditions. The sand dust made the slats jam, also early E versions were prone to slat jam. Wiring slats shut is plausible if you're operating in dusty conditions of Africa or Russian plains at summer. If other slat deployed and other was jammed, that would be most problematic. But if you had long, good runways - like you most likely would in Africa - wiring slats might not be a problem for landing."
Sand and dust, mud and ice, and a quirk with the E model.
Might explain it all ;)
Or as Rall said:
"Q: Did you use this extra lift from the slats in combat?
A: Not at all. I mean, its also a matter of experience of the pilot, you know? When I think of the Russian... This is another thing, of the Russian airfields. In the wintertime you had mud and fall. MUD. And we had problems. When you takeoff, you roll and roll, you know? You get the mud into the cooler, ja? And we tried to overcome this by all technical gimmicks which didn't work."
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Mud into the oil cooler intake under wing I assume that means.
Hey Angus, how is the tree situation in Iceland? I've read a book or 2 bout Iceland. Am of Norwegian descent.
Worlds strongest man was from Iceland.
How many Brits were stationed there in 1940? How many ships?
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Hey Agent.
The tree situation is .... low...not a lot of them.
Norwegian counts like a cousin.
World Strongest man, yes, and one after another. I think we had the title like 8 times.
To boost the ego of a micro-nation like us, we had Miss World at the same time. Untolerable, lol.
The Brits were stationed here, entering on the 10th of may 1940. Hitler went mad, he was a week late.
(Operation Ikarus I think)
Now, there is lots of warstories and warmaterial from here rather unknown to the rest of the worls. Some food for you:
- The USA took over the garrison of the island in most parts BEFORE entering WW2. That was Springtime 1941.
- One of the first Enigma machines caught by the allies was caught off the southern shore here when a U-Boot got overpowered by a well aiming single aircraft! I think that was in 1940, but can look it up
- The Garrison here was 50.000 strong in mid war. Due to the action of an Icelandic double agent, the Germans thought it to be more, - like double. This is told to have lead them to tying down more troops in Norway than necessary.
- Lots of ships stopped by in WW2. Entire convoys on the murmansk route would also regroup and refuel here. The sad PQ-17 went off from Iceland. In 1940 one of my grandfathers rode 200 km on his bicycle to see HMS Hood at anchor
- My other Grandfather was a fisherman. He turned to farming when the seas became dangerous, - German U-boats sank many a fishing boat. Ironically, my wife's grandfather, a German, was drafted into the U-boat service, being an engineer.
Thank god they never met..... :)
That was that. Enjoy ;)
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Well, interesting stuff. especially enigma. Wondered if Brits were thin in troop stength in 1940. Most say germans did not have shipping to invade Iceland. They did have big flying boats that could land in North fiords. Bay of Hunafloi is not too far from capital. Summer time would mean terrain not too rough for travel.
What is it, 7-800 hundred miles across from Norway?
A couple of indian kids grew up in Iceland from Newfoundland when Vikings left. They took them back to Iceland. The kids parents had died.
Be back soon.
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Hello, double-O-nine
The Brits were definately thin in troop strenght in 1940.
Many of their AA and cannon sites in the beginning were with dud cannons only. Made of wood.
Getting to the German invasion plans, there were 2 ships being prepared, both fast ocean liners.
It was a week or two that made the difference.
Your mileage from Norway is roughly correct, however our shortest neighbour (I will have to check this out better) is actually Scotland.
I never heard this about the indian kids, but of course about everything else regarding the viking explorations.
Will be back, gotta go :)
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Well that is interesting. I had the thought that captured Norwegian ships could be used. Brits were very busy in summer of 40 with BoB.
Resupply is next issue. I've been called an idiot for mentioning air supply & U-boat supply. It's not that far fetched. Many German aircraft have enough range, even for 2 way trip. Condors, Viking flying boats etc.
Food & shelter would be solved locally. I don't think resupply is the main problem with Iceland. Hanging on to it is.
Daughter of fire is a good Iceland book. Pirates from Tunisia took 200 Icelandic souls to middle east, ( white slavery ), Long ago. only 12 or so ever made it back.
Pirates have been a problem in Icelands past. As have English, & Russian fishing boats.
Get many Narwhals in your area?
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Hey again.
Narwhals, nope.
Submarine wrecks from WW2, yes ;)
look to http://www.uboat.net
The editor is an icelander ;)
There were some raids and therefor casualties. Condors and He-111 from Norway. They would sometimes sink some shipping, and take potshots at various things. My hometown got strafed in 1940 or so.
The supply of food wasn't all that bad, we have quite some agriculture, and the fishing grounds are good. There was a lot of export to the British during the war, which probably lead to the Germans strafing the boats.
Then to the pirates. It was quite a story, - they came all the way from Algiers.
Although the nation was short of weapons, they got beaten off on some locations, and even suffered some casualties. But they took slaves, yes, and some were later bought back by the Danish king.
Now, the fishing boats of the Brits were a nuisance, and we had "wars" with them some 4 times about the fish.
Cannons were actually used on the Brits, last time in 1976!!!
In Cod war II (out of 4) the RN had 38 military vessels around the country!!!!
Anyway, we won them all :D
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Cannons wow! Iceland beats England. Don't see that in history books much then do we?
Yes I think a german garrison would not have trouble eating or being resupplied from the air. Whether they could have pulled off an invasion is still an open question. British navy would have sunk resupply ships.
If not in 40, then for sure by 41 I think an allied landing to take it back would have taken place. But that would have given Germans better part of a year use of island.
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As a strategic point in the Atlantic campaign, Iceland was a must.
For shelter, refuelling, air ops etc. You can see on the Uboat.net that there are many sub wrecks around our island.
BTW, the British also occupied the Faroe Islands, - same purpose.
They were here on the morning of may 10th in 1940, - same date as the Germans rolled into the Netherlands.
We were really lucky that the Germans didn't beat them to it, - firstly the abovementioned resupply problem, secondly they had a reputation for being bad masters, and thirdly, - probably, - there would have been some fighting perhaps.
The Brits were rather welcomed, they didn't mess with internal affairs, and they payed for what they got, products, workforce etc.
It turned all out to be an economical BOOM, so the WW2 was actually mostly a very prosperous time.
The dark side was the sinking of fishing boats and merchant vessels under Icelandic flag, - even in 1945 the biggest passanger liner was torpedoed. German aircraft also occasionally appeared, bombed and strafed. Some crashed here or were shot down.
Then there was espionage, and double agents were also active!
Then to the cod wars. The moving of our fishing border was as follows, - 2-4 miles, 4 to 12, 12 to 50 ,and 50 to 200.
Every time we had to jostle with the English, quite a funny affair.
in 1973 it was 50 miles, and 1975-76 the 200 miles, - those were the toughest ones. The Brits sent frigates and tugboats, and there was a lot of bumbing into each others. The Icelanders had 6 patrol ships, like 1000 tons max, doing only 20 kts max.
The Brits sent frigates 3 times the size, with 36 kts, but less nimble, and very much more lightly built, - our patrol ships are built for sailing in driftice, so thick skinned.
The Icelandic tactic employed a secret weapon, hehe, a towed cutter unit used to snap the trawler's pulling wires, sending their entire expensive fishing gear to the bottom of the ocean.
So, there were dogfights when the British frigates and tugboats tried to block, and ships would on frequent occasions smash into each other.
There was one attempt for sinking, - a British frigate caught an Icelander by some 90 deg angle, and he tumbled to 70 deg listing. But he tumbled out of the attack and in his new position managed to cut a trawler net within a minute.
The same Icelandic captain used cannon, that was in 1976. He had ordered a British trawler to stop, but he steamed ahead. There was a warning shot, then he ordered the Brit to evacuate crew from the front quarters, which he promptly did. Then cannon shells were pumped into the front of the Trawler. there was ceize-fire so the Brit could explore the damage, then repeated a few times. The Brit never yealded, but had to return to docks instead.
Quite amazing stuff, I´ll see if I can find any links.
At that moment actually, political connection between the UK and Iceland was cut, and ambassadors called home!
Anyway, they gave up, and now everybody has their 200 miles, including the UK.
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Germans did not have a good naval plan. The Z plan was a compromise, so that germany was weak in all categories. Should have made mini carriers, more disguised raiders ready in 39.,(1st raider wasn't ready til 40! ),good armed transport craft, & of course loads of U-boats. hindsight is 20/20. & the age of the big battleship had not passed yet. More pocket battleships would have better use of steel.
Yes I did read about 50, then 200 mile limit. The book also mentioned Russian & Japanese ships.
In the book German raider Atlantis, it mentions the British would use the north fiords of Iceland for shelter when sea was rough. This was one reason Atlantis made it into Atlantic as she braved the storms while Brit ships were in the fiords.
Back to trees. many types of trees were attempted in Iceland. Some worked, some not. An apple tree was planted in Reykyavic & it only produced apples once, something like that. This was in 1840? Have to read it again. Some tees have been imported from Colorado, & some from Russia.
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Cool thread...lots of speculation. Although I can't vouch for what the German's actually did or did not do regarding slats I do have some experience actually flying with aerodynamic slats that might be relevant. I also agree with the comments as relayed by Grits. The Douglas A-4 had aerodynamic slats that appear to be almost identical to the German design...at least as well as I can recall from the last time I saw a WWII German design. This design is also the same as the North American F-86 and T-39 which share the same wing/slat.
Do slats stick? Yes. Even though they're relatively simple devices they still have to be cleaned, lubed and adjusted. Some of the individual planes I flew had a reputation for a sticking slat that the maintenance crew just couldn't get right. Maybe the wing was tweaked, maybe the tracks were worn, maybe someone ran into it at some time with a truck but the more flight time an airplane had the harder it was to keep them working right. The slightest bit of stickiness during preflight usually meant you'd see problems in the air. If we had maintence issues in Pensacola you can bet they were ten times worse in 1944 Germany.
Do they "pop" or "clunk" when going up or down? Absolutely. They're either in or out and the change is quick and noticable.
When one sticks can it cause the airplane to depart from controlled flight? Yes, especially if it sticks in the fully up position and you snatch on a buttload of aft stick. At low speed the airplane simply rolls off a bit on the stuck slat side; however, at high speed and if you're unlucky you can get a violent departure. To give you an idea of how critical the wing leading edge can be, some F-14 departures were tracked down to differences in the paint thickness and texture on the wing leading edge (which is a powered slat on the F-14). We ended up stripping the slats down and leaving them in bare metal.
When one sticks or if they deploy at different times does it affect your ability to do guns tracking? Yes, alot; however, if you're trying to do an evasive maneuver asymetrical deployment sometimes helps. Let's say you're doing a guns defense with a barrel role and you snatch and roll at the same time. The upgoing wing has higher AOA and its slat pops out before the other side...you'll get better initial roll so it can help.
Are there work arounds? Yes. As you approach slat deployment you can "pop" the nose up and force the slats out then keep the AOA you have. Aerodynamic slats typically deploy at one AOA and retract at a bit lower AOA so if you get them out they'll typically stay out unless you significantly lower AOA. Once you have them out it's more stable then with them in and you definently don't want to try to track right at critical AOA and have them popping in and out. This makes true guns tracking impossible.
Do slats affect lift? Yes. They shift the lift curve to the left. In most designs I've seen slats not only provide some boundary layer control but, since they slide forward and down they increase both the camber and area of the wing. Complex flaps can the same thing, sliding aft and down and when they're sloted they also assist boundary control on the trailing edge. Combining slats and flaps moves the lift curve left and up.
Do slats increase drag? Depends on how you look at it. At the point the slats are coming out induced drag is predominate and the higher the AOA, the greater the lift, the greater the drag. Since the slats permit a higher AOA you'll get more drag due to lift; however, by delaying the stall you reduce the drag that would be caused by boundary layer separation so it's a tradeoff. In reality you're flying where you can't go without the slats so drag isn't really the point, critical AOA and power are.
Is it reasonable to assume someone might want to fix the slats in the up position? Yes. As Grits mentioned the Blue Angels did exactly this (they also chromed them which was pretty sharp). Of course there is a trade off in that you lower your critical AOA and, at least in the A-4, the airplane is less stable in tracking as you approach stall. Although the Blues did this for formation flight, some of the Germans MAY very well have done the same thing for fighting especially given the conditions they operated and IF the slats were actually sticking in one position but I have no idea if they actually did or not...it's just a reasonable assumption. Personally, I'd think a smart pilot would just take slat operation into account and use them even if they were sticky but not stuck(ya otta use all the tools in your toolbox).
Why don't small civilian airplanes (puddlejumpers like the C-182) have aerodynamic slats? They add expense, complexity and maintenance issues for minimal payoff (just like simple vs fowler flaps). As others have mentioned, civilian STOL aircraft typically have fixed slats (which are really just leading edge slots for boundary layer control) and have a justification for other, more extensive high lift devices like fowler flaps, vortex generators and fancy wingtips but for typical general aviation it just isn't worth it. All modern fighters either have slats or leading edge flaps for both landing and maneuvering although these are now all powered and controlled by the Flight Control System.
Is AH accurate? Yeah, I'd say so. Like Grit's Dad I was amazed they modeled the slats and they sure seem pretty realistic to me, just glad they don't model maintenance issues.
Thought you all might find this informative.
Mace,
CDR USN (Ret)
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TY Mace, it was informative and nice to read first hand experiences of slats.
However, I'm not so sure if AH models slats accurately. This is why: The wing profile, say NACA 2412 has certain max AoA limit at certain R number, this limit for NACA2408 is lower (it's thinner). So we can see that the profile affects the max AoA. If the max AoA for 2412 is 15 deg for a certain R number the slat can extend the max AoA much furter for a cost of more drag, of course. So you should be able to pull more AoA that another a/c with NACA 2408 even without the aid of slats.
Flying a 109 in AH, you do not get the impression that the slat "extends" your max AoA, but only lets you pull as much AoA as a/c with larger wings without slats, as in fact it should allow you to pull quite a bit more than those. Combined with enough power the slats should be a good thing if turning is considered. Now they merely warn you of the incoming death in form of slow speed. It would be nice to have a AoA and G counter in E6B so I could prove myself wrong in this case...
:aok
-C+
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Originally posted by Mace2004
Thought you all might find this informative.
I did thanks..............
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Originally posted by Charge
Flying a 109 in AH, you do not get the impression that the slat "extends" your max AoA, but only lets you pull as much AoA as a/c with larger wings without slats, as in fact it should allow you to pull quite a bit more than those.
--Not necessarily if the basic wing (i.e.., without slats) has a low tolerance for high AOA or if the aircraft has a high wing loading in which case the slats may only help it be competitive with other wings. I have none of the charts that many in this game have in order to do a reasonable comparison but, just from my observation, the 109 series appears to have relatively small wings and probably higher wing loading.
Assume you have two identical aircraft with the same profile wing but one wing is smaller giving a higher wing loading. The smaller wing aircraft would have to pull higher AOA for the same turn radius and it will reach critical AOA first. Give the small wing slats and performance will improve but there's no way to know if it'll still be less than, equal to, or better than the larger wing without empirical data. Any of these results are possible depending on the abilities of the basic wing.
Personally, I wish HT would publish VN diagrams for all of the aircraft in the game which would give much more useful information than the speed profiles that are available. Obviously, one of the first questions people ask is "how fast is it?" I'd rather know how well it turns and at what speeds in comparison to other aircraft... corner velocity, max sustained turn, max instantaneous turn, etc. VNs are the charts we pulled out to determine how we would fight another, dissimilar aircraft.
Back to AH, regardless of slats or wing loading, the only thing we can really see is ability to turn in relation to others and there are of course many variables. I'd have to assume that HT modeled it correctly but who knows?
Mace
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Hi Mace,
>Personally, I wish HT would publish VN diagrams
Sounds interesting! How are VN diagrams organized?
(We had a discussion here on the most useful form of organizing data on aircraft manoeuvrability a while back, and we weren't happy with what we had back then.)
Regards,
Henning (HoHun)
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Vn (or VG) diagrams are velocity (V) over G (n). The vertical scale is G-load and horizontal is speed. There are different charts for different altitudes. Your lift curve starts at 1G and ramps up with speed until you reach the plane's G limit (also ramps down for neg G). If you go above the lift line you stall before you reach your G-limit. If you go above the G-limit you overstress your aircraft without using available lift. The right side of the graph is your mach/IAS limit. Using the graph you can determine instantaneous G available for any given speed. Corner velocity is that point where the lift line intersects your maximum G limit and shows that point at which you have the most G available without overstressing the aircraft. This is a point that you typically want to target. Too fast and you're G limited so you can't use all of your available lift. Too slow and you're lift limited and can't generate enough G to get your best turn without stalling. This equates to the speed for max turn rate since G determines turn rate. Note that this says nothing about turn radius just rate. When the diagram includes excess power you can determine the best speed for sustained turns and climb. You can see at what speeds you bleed energy and those that you can sustain or add e
Let's say you check your corner speed and see it's 300 kts but your opponent's is 450 (say an F-4). If you hit the merge co-speed at 450 kts he has his best turn rate available to him while you're G-limited. You can't pull the plane around as quick unless you bleed off that extra 150 kts and since you're fast you're flying a very large radius turn. If his best turn rate is better than what you have available then he gets turned around both quicker and in a smaller radius for a shot opportunity before you. Even if he doesn't get a shot he's gained angles on you and hits the second merge with an advantage. If, on the other hand, you slow to 300 kts at or right after the merge you can get around before him while he screams around in a huge arc. Think about hitting the merge in a Typhoon going 400 and your opponent is a Spit V going 300. Both of you go vertical and you in your typy come over the top only to see the Spit has turned inside you already, reversed and is pulling for a snap shot as you head down on the backside of you're loop. Sound familiar? You wouldn't be surprised if you had both Vn diagrams.
Obviously there's a lot more to consider but overall the Vn is probably the most useful single graph for maneuvering flight. Of course in AH we have a stall limiter; however, it would still be useful. There are those that disable the limiter and even those that don't would be able to use it since you'd know when fast is too fast and visa versa.
Mace
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Hi Mace,
>Vn (or VG) diagrams are velocity (V) over G (n).
Thanks, I understand. Were they plain V-n-diagrams or did they have some kind of excess power indication as well? Most players know the relative turning abilities by heart, but the relative energy combat capabilities of the aircraft are a bit more dfficult to visualize, and we have not found a good type of diagram for that yet.
Regards,
Henning (HoHun)
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Hohun
Yeah, as I recall they overlayed the Ps data on the Vn. Believe the left vertical axis was load the right was Ps.
Mace
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Mace2004, - Nice input, and very much so.
Did you read the whole thread? Takes patience to ponder through this one, but there is however some meat on the bones.
This is the thread that made me dig quite deep in the debate, and even earned myself a place on HoHun's sig list. Hell, to get some first account word on the slats I even phoned Gunther Rall, lol.
So, great to have all this confirmed, and a good education for some of us :)
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Hi Mace,
>Yeah, as I recall they overlayed the Ps data on the Vn. Believe the left vertical axis was load the right was Ps.
We were discussing turn rate over speed diagrams, which we found unsatisfactory. G over speed is not that different - which are the advantages?
Was the Ps information depicted in lines of equal Ps?
Regards,
Henning (HoHun)