Leading Edge Slats on the Me-109

[taildraggernut]

Slats are or should I say were in the 1930's/40's primarily a device to improve low speed handling qualities and cannot be anti-spin, the only true form of anti-spin is propper handling of the aircraft, slats simply make the behaviour at stall more benign but their effectiveness has a cut-off point beyond which there is nothing to provide these protections, in high speed manouvering the chances of exceeding those limits are much higher.

I believe the relevance of these extended discussions to the original subject is to do with what some people are expecting from the effect of slats, the original question I believe is almost impossible to answer without being able to disable the slats, and that is subject to whether they are actually coded as separate devices as opposed to the FM being modelled with simple wings that reflect performance with slats.

[Crumpp]

Slats are an anti-spin device. What is so hard to understand about it?

If you have ever flown an aircraft with slats, you can immediately notice the difference in slow flight and stall behaviors.

Here is the slats in my old airplane:

http://www.youtube.com/watch?v=-vbqgfjyW2Q

[taildraggernut]

Slats are NOT an anti-spin device...what is so hard to understand about it?

I have flown aircraft with slats....have you?

you can immediately notice the difference in slow flight and stall behaviors.

Right, now ask someone to make a video of the same aircraft doing high speed stalls taking the aircraft beyond the limiting angle of attack and we can compare the results.

[Crumpp]

Now hopefully you will be able to explain to us all exactly what are the mechanics involved in complete stall/spin avoidance once a slatted wing has been taken beyond it's maximum angle of attack?

Now your trying to morph the discussion into something else.

You keep confusing "anti-spin" device with a spin resistant airplane.

Spin resistant airplanes employ anti-spin devices such as wing cuffs, LE slats, and slots to build spin resistance.

What you are missing is the ability to put it all together. If we were talking about the entire wing being able to stall at once, then the airplane will enter a spin.

It takes a lot of work to do that in a Bf-109 by design.

First of all, only the outboard portion of the wing receives the benefit of the slats in the Bf-109.

In any airplane, the most desirable stall progression is for the wing root to stall first and the tips to stall last.

This leaves the wingtip unstalled and the ailerons effective.

The next feature of the slats is the automatic deployment. Air pressure operates the slats and they will deploy to exactly the position the wing requires for a given condition. That is why in a skid, they will asymmetrically deploy. For some reason, gamers tend to think "asymmetrical" deployment of the slats is a bad thing, it is not unless there is a malfunction of the slats. Instead, the slats deploy to exactly what the wings need automatically and unless the pilot looks out and is somehow psychologically disturbed by seeing the slats out at different amounts, the airplane skids normally without noticeable effect.

The last feature in the Bf-109 is the elevator control is set up so that with the wing root stalled, the pilot cannot continue to raise the nose. The Socata Rallye is designed that way as are many aircraft.

The designer uses control design to keep the pilot safe by limiting the moment the elevator can produce about the CG. This way, the wing tips remain effective throughout the stall. Cessna does this in a C-172 as well. Again, it is a common feature in a properly designed aircraft.
Now, Mtt did have to demonstrate spin entry and normal recovery in the Bf-109. They did this by adversely loading the aircraft to its rearward CG limit and modifying the slats to be pilot controlled. In other words, the airplane was at its rear most CG limit and the pilot could lock the slats so they did not deploy.

[Crumpp]

I have flown aircraft with slats....have you?

That is my airplane and I am at controls in the film.

[taildraggernut]

Originally Posted by Crumpp

That is my airplane and I am at controls in the film.

if you say so, hardly evidence though is it, a medium level turn pumping the elevator to make slats deploy.

Originally Posted by Crumpp

Now your trying to morph the discussion into something else.

You keep confusing "anti-spin" device with a spin resistant airplane.

I'm pretty sure I'm not the confused one in this discussion.....anyway...carry on.

Originally Posted by Crumpp

Spin resistant airplanes employ anti-spin devices such as wing cuffs, LE slats, and slots to build spin resistance.

Can I stop you here again....sorry but anti-spin would mean spin proof, resistance implies it's not proof, you know like waterproof vs water resistant, none of those devices can be considered a proof against spinning.

Originally Posted by Crumpp

What you are missing is the ability to put it all together. If we were talking about the entire wing being able to stall at once, then the airplane will enter a spin.

It takes a lot of work to do that in a Bf-109 by design.

............


The last feature in the Bf-109 is the elevator control is set up so that with the wing root stalled, the pilot cannot continue to raise the nose. The Socata Rallye is designed that way as are many aircraft.

The designer uses control design to keep the pilot safe by limiting the moment the elevator can produce about the CG. This way, the wing tips remain effective throughout the stall. Cessna does this in a C-172 as well. Again, it is a common feature in a properly designed aircraft.
Now, Mtt did have to demonstrate spin entry and normal recovery in the Bf-109. They did this by adversely loading the aircraft to its rearward CG limit and modifying the slats to be pilot controlled. In other words, the airplane was at its rear most CG limit and the pilot could lock the slats so they did not deploy.

and here finally (in bold) is the first bit of credible understanding you show, but subsequently you have exposed the real protection in this case to come from blanking the elevator, you do realise you have just excluded the slats completely from the equation, given that you could design an aircraft without slats that puts the elevator into the turbulent flow and it would have exactly the same pitch limiting effects, the side effect of that is you seriously limit the manouverability......is this starting to make sense or what?

wait a minute...MTT had to lock the slats but still had to put the CoG back too? why bother with the CoG? sounds to me like there was some crazy black magic going on with that aircraft and spin resistance had nothing to do with slats.....more and more NZTyphoons recently deleted comedy poster is making sense.