Spit/109 sea level speed comparisons in 1.08 beta patch

[Glider]

Originally Posted by Crumpp

That is a good point. We are talking about the test pilots who felt the Bf-109 was "embarrassed" by the slats opening in the turn.

I would not be surprised if the pilots did not operate the propeller at its most efficient point at the single data point the RAE used. That would throw off all of Gates assumption for the entire envelope.

In order to reproduce the RAE results, I have to drop the propeller efficiency to below average and assume VDM could not properly design a propeller.

As it happens yes they are. The UK had the first and at that time only test pilot training school in the world. As for being embarrased yes the Me109E was embarased by the way the slots opened, which no doubt was why they were redesigned for the Me109F. Unless you have a better reason for the redesign.

As for you having to drop the propeller efficiency to get the same results, working on the basis that you are not a trained test pilot then I can only assume that your model is wrong. I know you believe that the test pilots are not important but if I had to pick between their hard earned experience and training, backed up be the science of the day and access to the real aircraft, against your maths and how you read documents, I would go for the experts.

[5./JG27.Farber]

The title of the thread is:

Spit/109 sea level speed comparisons in 1.08 beta patch

So, we know that all aircraft are two slow, surely we just need a general consensus of which top speeds are correct given the fact that:

• 109 speed tests are not full throttle, 1.3 Ata is the maximum recorded/logged
• Aircraft have a gate system for more power
• speeds are slightly different on multiple tests
• Specific engines

So from this can we just agree on some numbers to submitted?

[Talisman]

Crumpp,

You said:

"That is a good point. We are talking about the test pilots who felt the Bf-109 was "embarrassed" by the slats opening in the turn.

I would not be surprised if the pilots did not operate the propeller at its most efficient point at the single data point the RAE used. That would throw off all of Gates assumption for the entire envelope.

In order to reproduce the RAE results, I have to drop the propeller efficiency to below average and assume VDM could not properly design a propeller".

Given what Rall said below, would you not say that the "embarassed" remark was fair comment? If an event and effect designed for taking off and landing happens in the middle of fast air combat with no warning, when you do not intend it to happen, it is not a good thing is it? Esp if the slats do not function in an even way as per the design function. I would have thought that this effect should be part of the CloD FM. Thoughts?

Talisman

Me 109 E:
"And there I discovered the first thing you have to consider in a 109. The 109 had slots. The slot had a purpose to increase the lift during takeoff and landing. In the air automatically it's pressed to the main wing. And if you turn very roughly you got a chance, it's just by power, the wing, the forewing, comes out a little bit, and you snap. This happened to me. I released the stick immediately and it was ok then. "
- Major Gunther Rall in April 1943. German fighter ace, NATO general, Commander of the German Air Force. 275 victories. Source: Lecture by general Rall.

Me 109 E/F/G: - The plane had these wing slats and you mentioned they pop open uneven?
"Two meter slots on fore wings. The reason was to increase the lift during low speed take off and landing. To reduce the length of runway you need. In the air, if you make rough turns, just by gravity, the outer slot might get out. You can correct it immediately by release of stick, you know? Only little bit, psssssssht, its in, then its gone. You have to know that. And if you know it, you prevent it."
- Major Gunther Rall. German fighter ace, NATO general, Commander of the German Air Force. 275 victories. Source: Lecture by general Rall.

[Glider]

Its only fair to point out that problems with automatic leading edge slots that opened suddenly, were not unique to the Me109 at this time . The Westland Whirlwind also had the same issue but the squadrons decided in most (maybe all) cases to lock them so they wouldn't come out and live with the extra landing speed.

The Luftwaffe with the greater emphasis on these devices changed the design on the Me109F so they opened gradually. Kurfurst knows more than me about this but I think thats the basic situation.

[TomcatViP]

This is not correct. They hve always open gradully. The diff in pressure makes them open as a function of it. It's a suction effect. The more, the wider ( humm.... stay focused.. )

The prob with the wider LE was IMOHO with the prop wash that in certain situation (yaw) prevented one slat to fully open. Having yaw angle is fairly comune during a DF unless you stay focused on your slip angle.

~S!

[bongodriver]

Originally Posted by TomcatViP

This is not correct. They hve always open gradully. The diff in pressure makes them open as a function of it. It's a suction effect. The more, the wider ( humm.... stay focused.. )

The prob with the wider LE was IMOHO with the prop wash that in certain situation (yaw) prevented one slat to fully open. Having yaw angle is fairly comune during a DF unless you stay focused on your slip angle.

~S!

This is not correct, when the aircraft is pulling tight turns the g load on the slats makes them snap open, they are designed only to open gently at slow speeds for landing and take off.

[JtD]

The leading edge slats of the 109 work through air pressure distribution and this is depending on the angle of attack. The slats deploy gradually over a small range of the angle of attack, making it possible for them to snap open in abrupt manoeuvres, but they can also be made deploy gradually when increasing angle of attack gently.

The leading edge slats were reworked with the F series in that their span was reduced and the mechanism simplified. I don't think the deployment was changed a lot.

[Glider]

In my mind Kurfurst is the person for this, but what isn't in question is that they were redesigned for the 109F

[Crumpp]

Given what Rall said below, would you not say that the "embarassed" remark was fair comment?

No.

Here is handley page automatic slats in operation on my old airplane:

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

Unless they are new to you, the slats are nothing of note as far as piloting goes.

What do for the airplane is outstanding. You can pull some insane body angles with them.

Here is another video I made on the way to work. It was beautiful day to fly.

http://www.youtube.com/watch?v=UdgohV4gpXE

[SlipBall]

Pilot notes to a whole new level