Hi Juha,
>The term Emberassed might come from the fact than in turning fight slats began popping out separately when 109 hit the wake of the other a/c and so ruined aiming. But what I remember on Finns experiences British seemed to have overstated this problem.
Absolutely. Radinger/Schick in their "Me 109" note that the Bayerische Flugzeugwerke and the Deutsche Versuchsanstalt für Luftfahrt undertook extensive trials of the slats in a major test program (worth 2,000,000 Reichsmark), which resulted in the deletion of the locking mechanism which originally held down the slats while the flaps were extended by less than 10 degrees. (If you're familiar with the US analysis of a captured Me 110, they found the remnants of such a locking mechanism which had been disabled, so it was not only used in the Me 109.)
Another series of test flights were undertaken in 1936 to determine if there was any danger of the slats during spins. Gustav Lachmann of Handley Page suggested that the slats should be equipped with a pneumatic retraction device to safeguard against the opened slats making the spin irrecoverable, but it turned out that this device had never to be used during the trials.
The results of these test flights were that the handling characteristics of the Me 109 were made much more docile in turns and aerobatics with flaps retracted by the freely operating slats.
If you read the French comparison report on the D.520 vs. Me 109E trials, you'll find that the two fighters had virtually identical turn rates at the test altitude, but the Me 109 could be flown reliably at the edge of the stall with sufficient warning to stay in the turn, while the D.520 lacked such a warning and sooner or later flicked out of the turn when the pilot inadvertently flew it into the stall.
(The Spitfire could be reliably flown on the edge of the stall like the Messerschmitt too, relying on aerodynamic wash-out to achieve a gradual instead of an abrupt stall. For the record, I don't think the Me 109 could match the Spitfire's sustained turn, except perhaps when you take a particularly heavy and poorly performing Spitfire variant like a tropicalized Spitfire V against a very light and well turning Messerschmitt variant like the Me 109F-4.)
Regards,
Henning (HoHun)