Leading Edge Slats on the Me-109

[Crumpp]

Mark Hanna was killed in a Buchon in a low speed low altitude departure...

Different airplane but yes, the nose up attitude at the stall and descent can be very dangerous if the pilot is not on his toes.

Your stalled and the danger is you don't realize in time.

[taildraggernut]

Originally Posted by Crumpp

Different airplane but yes, the nose up attitude at the stall and descent can be very dangerous if the pilot is not on his toes.

Your stalled and the danger is you don't realize in time.

everything behind the firewall is a 109....including the slats.

[taildraggernut]

Originally Posted by Crumpp

It is a fact the RAE pilot felt that way. It is also a fact the RAE had no defined stability and control standards outside of pilot opinion. They did not have the measurements and definitions of the NACA or the RLM.

It is also a fact if you apply those definitions and standards, the Bf-109 was designed to be thrown around the sky at maximum performance the physics and physiological limits of the real world allowed.

Gust factor is a very real limit to airplanes. Flying around the other day, I had to stay below Vno just cruising because the sky was so bumpy.

If you pull a 6G maneuver and hit a gust acceleration, you have damaged the airplane. Not only that, 6G's sucks!! It is very uncomfortable and exhausting! IIRC, the USAF did a study and a fighter pilots ability to accurately track a target for a gun solution is degraded ~85% of normal after a few seconds exposure to just 4.5G's.

What Mtt did was apply a stability and control standard to ensure the pilot could quickly and precisely maneuver the guns onto target in order to make the most accurate shot possible. They tried to ensure the airplane achieved maximum performance to get where it needed to be in a condition to destroy other airplanes.

The designed a stable shooting platform and built an airplane around it.

Actually I remember a thread that proved your theories the RAE had no established stability and control standards completely false.

The 109 was designed to be flown at high speed towards a target to throw bullets at it and then GTFO in a hurry too, a small wing with such a high loading was not designed to be thrown around and that is why they put slats on them, to improve it's low speed handling.

why does 6g suck? I personally like aerobatics and have been to 7g, of course you tend to avoid manouvering in conditions you 'know' likely to be gusty.

[II/JG53 Rolf]

AOA - Sir, with all respect, could you explain how could uneven deployment of slats cause the above effect? I mean it, sir. No irony. Say, we have a Bf-109 E4 in a tight right horizontal turn trying to gain enough lead to kill a spit. It's on the edge of stall. Does it mean that the slat on the right thing wouldn't deploy entirely but, say, lower part more than the upper part. There was construction a diagram shown here, where it shouldn't be possible so it must have been malfunction - and sir, all planes were not the same (e.g. max speeds show average number, actual outputs of the plane could be +/- 5-10%, up to 20% in case of Russian planes). Or does it work differently (I could be missing something.)

And your point about me ignoring something in your post wasn't valid I am afraid, as I tried to explain that the cause could have been the actual experience of the pilot. There was mentioned before that there could be mechanical problems with slats because of dust, so they didn't deploy evenly or at all. However, I would say that this is simple malfunction, not a construction thing.

[ACE-OF-ACES]

Originally Posted by II/JG53 Rolf

AOA - Sir, with all respect, could you explain how could uneven deployment of slats cause the above effect? I mean it, sir.

No need for me to explain it..

In that based on Erwin Leykauf quote, an actual WWII Bf109 pilot we know that it happened, i.e.

Originally Posted by Oberleutnant Erwin Leykauf

Less experienced pilots could put a Bf 109 into a stall and spin when the slats deployed on one wing and not the other in a tight turn. When slats deployed unevenly in tight turns, they would disrupt the airflow, causing the ailerons to ‘snatch’ enough to shake a Bf 109, spoiling the pilot’s aim

Agreed?

Or are you saying you know better than Erwin Leykauf? Or that Erwin Leykauf was lying when he said that?

Eitherway you seem a little confused..

Allow me to bring you up to speed!

Back on page 19 robtek ask for PROOF, i.e.

Originally Posted by robtek

Now there you have to bring some proof that the assymetric action of the flaps, which was intended, was causing spins.

To which I did not bother providing in that I knew robtek would just poo poo anything I did provide

After that Crumpp felt the need to chime in with his cut-n-paste Bf109 myths site 'take on' what actual WWII pilots said as proof that uneven slat activation can NOT cause a spin because the Bf109 myth site, FOR SOME REASON left that part of Erwin Leykauf quote out of thier section called "Wing leading edge slats - good or bad?".

My guess is that it was just to black and white for them to 'spin' (pun intended) what Erwin Leykauf said into something positive..

So the Bf109 myth site conventally left that part of the quote out of their section devoted to uneven slat activation issue.

Talk about poster boys for 109 bias!

After seeing that weak attempt by Crumpp to present the biased Bf109 myth site reinterpretation of WWII pilot quotes as proof I decided to post Erwin Leykauf quote here as PROOF of what I was saying

Hope that helps!

[II/JG53 Rolf]

AOA - Sir, how could this happen? If the slat opened on the lower wing, it would increase lift there thus preventing stall for a few moments. What the pilot said was that less experienced pilot went into the stall/spin (stall first spin later) when this happened. On previous pages there was a description of RL pilot doing the same with only one difference - he was very experienced and recovered without a problem. The point is - you have a pilot with say 150 hours in the heat of the fight to the death who is turning hard to avoid being shot at or to gain a shot on an enemy - he could have missed those warnings. So the pilot told the truth, but as in many examples from that era it is only part of it. In the same manner you are ignoring his quotes telling the opposite. If we just step back a bit - to sum it up:
1) Slats were designed to open unevenly because the aerodynamic effects were uneven on both wings, especially in high AOA.
2) Slats helped at stall speeds at low speeds, discussion is held about high speed with not much evidence for either case in this thread.
3) Slats could have malfunctions as any other part of a plane - not all planes and pilots have the best ground crew. The slat then could open partially which could cause inexperienced pilot to stall/spin.
4) Recovery from the spin of slats equipped 109 was considered easy.
5) This whole thread was started because of stall and spin characteristics of bf-109 in CLOD game .

[Crumpp]

Actually I remember a thread that proved your theories the RAE had no established stability and control standards completely false.

Really?

Wow, you should tell the engineering departments of every major university because they are teaching the wrong information.

Maybe you should tell one of the pioneers of stability and control engineering. A British engineer who strived during the war and after to get the RAE on a defined standard after his experience working with the NACA. What is even more funny is the fact stick force per G, which Gates developed, was adopted by the NACA as part of the 1942 standard!

The United States NACA adopted a British engineers ideas and made them standard long before the British RAE listened to their own guy! That was the basis of his invitation to come to the United States and observe the stability and control developments at the NACA.

Here is the first page of the proposed standards for longitudinal stability, in fact.

I think World War II in Europe ended in May 1945. Pretty sure September 1947 is after the conflict was over....

[ACE-OF-ACES]

Originally Posted by II/JG53 Rolf

AOA - Sir, how could this happen?

Does not mater how..

In that based on Erwin Leykauf quote, an actual WWII Bf109 pilot we know that it happened, i.e.

Originally Posted by Oberleutnant Erwin Leykauf

Less experienced pilots could put a Bf 109 into a stall and spin when the slats deployed on one wing and not the other in a tight turn. When slats deployed unevenly in tight turns, they would disrupt the airflow, causing the ailerons to ‘snatch’ enough to shake a Bf 109, spoiling the pilot’s aim

Agreed?

Either way you seem a little confused..

Allow me to bring you up to speed!

This all started with me saying the following..

Originally Posted by ACE-OF-ACES

Especially in light of the fact that there are many accounts of how leading edge slats CAUSED spins!!

Where, for what ever reason, the leading edge slats did not deploy evenly and thus induces (CAUSE) the plane to spin..

Not to mention the accounts of the leading edge slats POPPING out suddenly such that they 'changed' the aerodynamics such that the pilot had to quickly adjust his controls.. In essence startling the pilot such that he may have over compensated and CAUSE the plane to stall or even spin

To which robtek responded asking for proof of the accounts, i.e.

Originally Posted by robtek

Now there you have to bring some proof that the assymetric action of the flaps, which was intended, was causing spins.

Initially I didn't bother digging up the historic accounts because I knew robtek would just poo poo anything I did provide..

But after that Crumpp felt the need to chime in with his cut-n-paste Bf109 myths site 'take on' what actual WWII pilots said as proof that uneven slat activation can NOT cause a spin because the Bf109 myth site, for some reason they conventually left that part of Erwin Leykauf quote out of their section called "Wing leading edge slats - good or bad?".

My guess is that it was just to black and white for them to 'spin' (pun intended) what Erwin Leykauf said into something positive..

But I digress..

After seeing that weak attempt by Crumpp to present the Bf109 myth site reinterpretation of what WWII pilot said as PROOF

I decided to post Erwin Leykauf quote here as PROOF of what I was saying..

IMHO there is no debating this issue

Unless your willing to say Erwin Leykauf was mistaken and you know better than he on how the Bf109 flys, or your willing to say Erwin Leykauf was lying?

So in summary

1) I pointed out uneven activation of the slats can cause spins..
2) rotek ask for proof of uneven activation of the slats can cause spins.. (aka bring it)
3) I provided proof of uneven activation of the slats can cause spins.. (aka brung it)

Hope that helps!

[Crumpp]

everything behind the firewall is a 109....including the slats.

Exactly!

You have an airframe designed for one engine that is now having to work with another one.

This is why STC's are required and you just cannot swap motors in certified design airplanes.

The merlin prop swung at a lower rpm, weight is different, and the thrustline was higher. At least it turned in the same direction.

You do understand airframe are built to counteract the effects of spiral slipstream and torque?

That is why engine mounts/firewalls are angled and verticle stabilizers angled.

Mounting an engine with different properties results in different handling qualities.

Why are we even discussing this and what does it have to do with effect of the slats?

Is it just your justification for using an example which has nothing to do with the original topic?

[Crumpp]

II/JG53 Rolf,

My suggestion would be just to ignore AoA, ie, TAGERT.