Auto leading edge slats of the 109

[Sternjaeger]

Yes, this is why there are slats and slots: they both generate drag in exchange of enhanced laminar flow, but the slat can retract, whilst a slot is fixed. 

 

In order to have a better understanding of the aerodynamics involved with slats, watch this video (this is the bit when they talk about slats, but the whole thing is very interesting)

 

http://youtu.be/q_eMQvDoDWk?t=8m28s

Edited November 18, 2013 by Sternjaeger

[MiloMorai]

How did a/c operating in adverse conditions like found in N. Africa, Italy and Russia effect the operation of the slats?

[NZTyphoon]

Just for interest attached is a 1928 Flight article in which Fredrick H-P discusses the origins and concept of what were then called slots;

 

Second is a NACA translation of a German report on H-P slats written in 1932 (it is possible that Messerschmitt, amongst others, used this and similar reports to evaluate the use of slats on his designs - does anyone have any more info on this?)

 

Handley Page Lecture on Slots 1928.pdf

 

Further Flight Tests Effectiveness of H-P Slats (Germany 1932).pdf

Edited November 18, 2013 by NZTyphoon

[Sternjaeger]

How did a/c operating in adverse conditions like found in N. Africa, Italy and Russia effect the operation of the slats?

 

well, that's a good question. It was common practice for the 109 ground crews to push the slats back in the wing once the planes were parked, this to avoid dust/snow/dirt and other particles to get in and cause problems. 

 

I suppose factors like wing icing could have caused problems, but again, as long as you're on a critical AOA and speed, a malfunctioning slat would have caused only a certain amount of handling problems. There were far more prominent forces involved, i.e. the engine/propeller torque.

[Sternjaeger]

sorry, I meant "unless you are on a critical AOA and speed". This editing limitation is a bit pants..

[Crump]

 

maintain lamina flow and prevent the wing from stalling

 

 

It seems to be developing in this thread some idea that laminar flow being increased is the effect of slots.  That is akin to saying " the reason he fell is due to the impact with the earth".

 

All boundary layers have certain parts.  One of these is laminar flow and the other is turbulent flow.  Laminar flow is low energy, low drag, and low lift flow. 

 

Turbulent flow is high energy, high drag, and high lift flow.   An increase in laminar flow is the result of the fact all boundary layers are comprised of a laminar and a turbulent portion.  An increase in laminar flow is NOT the design intention of slots.

 

 

Adding dimples to a golf ball to increase the distance it travels is an example of the benefits of increasing turbulent flow.

 

The effect of slots is to directly increase the Angle of Attack and the CLmax the airfoil section is capable of attaining without the slots.  Slats create a slot in the wing and some slat designs also increase camber which will show as a shift in the entire polar.

 

 

 

 

 

So, the effect of a slot is to create turbulent flow which energizes the boundary layer and delays separation of flow over the airfoil section.  Pretty simple and effective in function but definitely not a device intended to increase laminar flow. 

http://www.coaportal.com/resources/Aerodynamics/12-High-Lift-Devices.pdf

[DD_bongodriver]

Crump doesn't appear to know the difference between slots and vortex generators, slots do not add energy by creating turbulence, they add it by accelerating the airflow over the surface of the wing, vortex generators effectively add energy by reducing surface drag which allows the boundary layer to retain it's energy for longer, it's all clearly explained in the .pdf he just linked, note how the section on slots makes not a single mention of creating turbulent flow.

[Sternjaeger]

 

Adding dimples to a golf ball to increase the distance it travels is an example of the benefits of increasing turbulent flow.

 

The effect of slots is to directly increase the Angle of Attack and the CLmax the airfoil section is capable of attaining without the slots.  Slats create a slot in the wing and some slat designs also increase camber which will show as a shift in the entire polar.

 

Oh my God man, you've got such a confusion in your head!!! 

 

First of all slots, slats and vortex generators are three different things.

 

We are talking about slats here, whose sole purpose is to ensure a continuation of laminar airflow on the wing upper surface at high AOAs. That's it. No other jiggery pokery involving golf balls, turbulence and bananas. 

 

I feel like we have to go through the basics of "why a wing flies" here..

[Crump]

Who mentioned vortex generators?
 

[Crump]

Here you go....

 

 

Edited November 18, 2013 by Crump

[Crump]

Sternjager,

 

I have bongodriver on ignore so I did not read his post.  That appears to be where you got the "vortex generators" from.  Vortex generators are high lift devices as well as being classified as "energy adders".  As such they do create turbulent flow to delay separation but they are not slots or slats.

[Crump]

Slots/slats must be incorporated into the design from the beginning.  They represent an increase in complexity and weight due to the mechanism required for employment.

 

Vortex generators offer the advantage of being light weight and have the ability to be added after the design phase of the aircraft.

[Sternjaeger]

Who mentioned vortex generators?

 

You know, all my confusion resulted in a 3.9 GPA and a Master's degree in Aeronautical Science, thank you very much.

 

To be honest that's even more disconcerting. 

 

Ok, I guess I'll have to go through the ABC here, give me a minute or two...

[Sternjaeger]

Yes, for what is worth I would recommend removing bongo from the ignore list, you can just refrain from replying to him if he really bothers you.

 

And before I go through the basics (right now I don't have much time or will to be honest, but I guess many people would find it of use), do we at least agree that slats help delaying the laminar airflow separation at high AOAs?

Edited November 18, 2013 by Sternjaeger

[von_Tom]

BOOOOOORING!

 

 

All you need to know about slats is:

 

1.  They pop out sometimes.

 

2.  They pop back in.

 

3.  There are little pixies in the wings that push them in and out.

 

4.  They kinda help depending on the airflow but not always, and sometimes it's a bad thing that they've popped out.

 

 

I will now take the plaudits for clarifying the whole slats issue.

 

I thank you.

 

 

Hood

[Crump]

ok, so your take is that the Florida Institute of Technology College of Aeronautics is wrong as well as the Naval Air Systems Command?

 

It is not you that is wrong, it is them?

 

You need the address to write them with your explanation? 

[DD_bongodriver]

Yes Crump's article highlight explains how a turbulent boundary layer is desirable given the choice, what it doesn't say is that slats don't create a turbulent boundary layer but employ a different means of re- energising the boundary layer, his previous article explained that and it is because the slotted channel formed by the open slat accelerates the air going through it which is what puts energy back into the boundary layer, it suits me fine he has me on ignore, it spares me from the cheap insults every time I point out his confusions, sadly he has never been very true to his word and it's an inevitability that at some point he will come back with another retort, probably something predictable like claiming he is infallible because he is using quoted articles from reputable establishments without realising he often misinterprets the information he is quoting.

[JtD]

If we only kept posts with even a little value, this topic wouldn't be a page long. It's so fing annoying.

[Kurfurst]

I think the developers have a fairly good idea and tests to create an accurate generic slat modelling - after all, it was a feature on the Soviet Lavochkin series fighters as well. But this thread doesn't seem to serve any real purpose, other than a regular battleground for some members... at the same time it utterly fails to add anything substantial on any pecularities on the subject, the auto leading edge slats of the 109.

[Crump]

 

If we only kept posts with even a little value, this topic wouldn't be a page long. It's so fing annoying.          

 

 

Why don't you contribute something instead of disparaging remarks?  Perhaps you can prove that "energy adders" such as slots/slats really means trying to increase low energy laminar flow instead of high energy turbulent flow?

 

But this thread doesn't seem to serve any real purpose, other than a regular battleground for some members

 

 

I agree, I think the purpose of this thread was too simply troll.

[Sternjaeger]

Right, I'm gonna try this (and I know I will regret it). 

 

Crump, can we please have a step by step approach to this, so we see where the differences are? 

 

1) Do we agree that the efficiency of a wing is dependent on the behaviour of the airflow on the upper surface, and that when we reach a certain AOA (namely 15 degrees and above), the airflow starts mutating from laminar to turbulent, causing eventually the wing to stall?

Edited November 18, 2013 by Sternjaeger

[Crump]

 

Crump, can we please have a step by step approach to this, so we see where the differences are? 

 

 

 

The aerodynamics are explained already.  

 

There is no need to prolong the discussion.  Your issue is not with me, but the Florida Institute of Technology College of Aeronautics and the US Navy Department of Aviation as well pretty much the entire Graduate level education system in Aeronautics.

 

So please just leave me out of this

 

http://forum.il2sturmovik.com/topic/2035-auto-leading-edge-slats-109/?p=49678

 

A very simple and elegant example of how energy adders work as high lift devices:

 

 

If you want to get deeper into the aerodynamics, there are two types of flow around an object: laminar and turbulent. Laminar flow has less drag, but it is also prone to a phenomenon called "separation." Once separation of a laminar boundary layer occurs, drag rises dramatically because of eddies that form in the gap. Turbulent flow has more drag initially but also better adhesion, and therefore is less prone to separation. Therefore, if the shape of an object is such that separation occurs easily, it is better to turbulate the boundary layer (at the slight cost of increased drag) in order to increase adhesion and reduce eddies (which means a significant reduction in drag). Dimples on golf balls turbulate the boundary layer.

 

http://www.howstuffworks.com/sports/golf/basics/question37.htm

[Sternjaeger]

dude, why are you avoiding answering the question? Do you agree or not? 

 

Nobody is questioning the properties of laminar vs turbulent airflow, I'm asking you which one generates lift? 

[LG1.Farber]

It has already begun.... 

 

OK, here are the rules:

 

• No answer must be less than 200 words, preferably 800. 
• Do not forget to rebut all claims against your argument and make sure you go down each and every nitty-gritty avenue and back ally.
• All graphs are legit, those made as prototype, enemy captured examples, ones from Jane's video game and the one you made in your bed room as long as they support your argument.
• If you give concession in any part of your argument then you are automatically disqualified.
• This thread must reach at least 250 posts to be recognised by the community and no less than 900 to become fact for eternity.
• Alliances may be formed to brow beat the opposition.
• The side with the most posts will be victorious when the thread is locked.
• The thread will be locked.
• Extra points can be scored for having the most graphs, diagrams and reports, extra points if you snip them to support a fraudulent argument.
• People who hold any sort of pilot qualification know everything about flying.
• Engineers are 2nd to actual pilots.
• Pilots know how WW2 aircraft handled.
• Flying WWII flight sims means you were in WW2.

 

Now I want to see a good dry and boring exchange of dialogue that niether side is listening to.

 

 

 - Gentlemen to your archives!

 

 

Edited November 18, 2013 by 5./JG27Farber

[DD_Crash]

Hood might be right about them pixies

[Sternjaeger]

guys please, I'd like to carry on exchanging educated information with Crump & co. in this thread without having it being locked.. this is not referred to anyone in particular, it's just a message to all the friends here. If it bothers you, please just ignore the thread, thank you.

Edited November 18, 2013 by Sternjaeger

[JtD]

Why don't you contribute something instead of disparaging remarks?  Perhaps you can prove that "energy adders" such as slots/slats really means trying to increase low energy laminar flow instead of high energy turbulent flow?

Who the f cares.

 

I think the purpose of this thread was too simply troll.

It certainly wasn't the original intention of the OP to troll, that's something you've made out of it.

 

guys please, I'd like to carry on exchanging educated information with Crump & co. in this thread without having it being locked.. if it bothers you just ignore the thread, thank you.

Then maybe you guys can go and start another topic?

Edited November 18, 2013 by JtD

[Sternjaeger]

we're talking about 109 slats mate, but there is some confusion on their function, and that's what we've been trying to ascertain. 

[AndyJWest]

Big whirls have little whirls that feed on their velocity,

 

and little whirls have lesser whirls and so on to viscosity.

 

Lewis Fry Richardson https://en.wikipedia.org/wiki/Lewis_Fry_Richardson

[von_Tom]

Hood might be right about them pixies

 

 

 

Damn right!

 

Hood

 

 

ps used to cycle around Buckley when i was at Chester law school.

[Quax]

If we only kept posts with even a little value, this topic wouldn't be a page long. It's so fing annoying.

 

I am already sorry, i said anything. But i learned the lesson

[JtD]

Which is exactly what shouldn't happen.

[Crump]

No Quax, I don't think you were trolling but definitely others in your thread.  That is why I said what I said:

 

Crumpp says:

 

There is no need to prolong the discussion.  Your issue is not with me, but the Florida Institute of Technology College of Aeronautics and the US Navy Department of Aviation as well pretty much the entire Graduate level education system in Aeronautics.

 

 

I don't feel like reinventing the wheel in some silly internet discussion about whether or not engineering convention as is taught in most major universities is correct.  I am sure the game developers understand slats, how they operate, and the benefits. 

[Sternjaeger]

Quax is the one that initiated the thread mate.

 

You don't need to reinvent a thing, but I need to understand if our exchange of opinion starts from common grounds.

 

Nobody is listening to you or giving you more credit just because of your studies, and all I asked for was to answer a simple question, can you indulge me at least on that please?

[LukeFF]

Game, set, match to Victory205. 

[Bearcat]

Bongo check you PMs.

[DD_bongodriver]

Nothing yet BC...

[Bearcat]

Now.

[DD_bongodriver]

Loud and clear

[ATAG_Slipstream]

Of course we will be able to try out the theory next week hopefully, when the F4 is released. I assume everyone in the thread has BoS? It is after all the BoS forum and I would hate to think some people are just carrying on from other arguments on other forums...

Edited November 18, 2013 by 9./ZG26Oster