Spit/109 sea level speed comparisons in 1.08 beta patch

[Kurfürst]

Originally Posted by Glider

Crumpp
You are reading something into the paper which isn't there and as a result are making an incorrect assumption.

You are right in some of what you say but have ignored other parts of the quote. The paragraph can be summerised as follows

a) An accurate calculation of the turn performance is dependent on an accurate measure of the CL max in level flight
b) The only way that the CLmax can be accurately measured is the use of the trailing static head.
c) It is difficult to do (this is the part which you highlight)
d) Despite it being difficult it has been successfully done on both the Spitfire and Me109 Nope it was not done on the 109
e) That the method used by the NACA is not as reliable and gave a misleading result According to RAE...

By ignoring the other relevent parts your assumption that the RAE had to calculate the results because they couldn't measure the CL max is fundamentally flawed.

No, it's correct, RAE admits that it has estimated Bf 109 Clmax values from earlier Spitfire flights, and did not measure them.

The " stall boundary " depends on an estimate of CL max at full throttle. In the case of the Spitfire this has been measured in flight, while the Me.109 figures were based on the Spitfire results; tables of the assumed values of CL max are given in Fig. 17. CL max falls off as g is increased, because the stalling speed increases as g gets larger, thus lessening the slipstream effect.

In contrast, RAE only measured Clmax in throttled back conditions:

Only one flight was made, as operating a suspended static head from a single-seater aircraft with a rather cramped cockpit is difficult.[b] Stalling speeds with engine throttled right back were measured/b] with flaps and undercarriage up and down, and the speed at which the slots opened were also noted ; in every case both slots opened almost simultaneously.

http://kurfurst.org/Tactical_trials/...ls/Morgan.html

Its because they were able to get an accurate measure of the CL max in a glide and max throttle that an accurate calculation of turn performance was possible. I should add that the RAE did exactly the same with the Me109 so these are by far the best calculations around.

Nope. What RAE did can be best described as a reasonably close estimate based on guessworked Clmax, with wrong weight, and with wrong power. REA did not measure full throttle Clmax on the 109, they have estimated that from results with the Spitfire... so who's quoting out of context now, David?

The most accurate calculations for the Me 109 turn capability are those done by Messerschmitt A.G., for obvious reasons.

[Glider]

Originally Posted by Kurfürst

No, it's correct, RAE admits that it has estimated Bf 109 Clmax values from earlier Spitfire flights, and did not measure them.

This paper clearly states that these measurements had been successfully done on the Me109. and it is clear that they had been measured on the Spitfire, Me109, Buffalo and Whirlwind.

Only one flight was made, as operating a suspended static head from a single-seater aircraft with a rather cramped cockpit is difficult.[b]

So you agree that they were measured

Stalling speeds with engine throttled right back were measured/b] with flaps and undercarriage up and down, and the speed at which the slots opened were also noted ; in every case both slots opened almost simultaneously.

http://kurfurst.org/Tactical_trials/...ls/Morgan.html

And you agree that they were measured in landing configuration (flaps and gear down), plus gliding config (with flaps and gear up).

It should be noted that this section in the paper is titled
Stalling Tests 4.4 4.41 determination of CL max
Would you really expect them to comment on the CL max at full throttle during stalling tests?

However, you are corect when you say that the CL max at full throttle was based on the SPit figures but the RAE did have the accurate figs on the Stall and Gliding configs which is half the battle so would be a good estimate

Nope. What RAE did can be best described as a reasonably close estimate based on guessworked Clmax, with wrong weight, and with wrong power.

Let me reword this for you
What RAE did can be best described as a close estimate of CL max at full throttle based on known Clmax for Gliding config.

so who's quoting out of context now, David?

I would say both of us missed something. However Crumpp when commenting on the RAE reply on the NACA tests missed a heck of a lot.

One obvious point which no one including me has mentioned, is that the RAE did have the 109. If their calculations said that one was better than the other at something, they had the aircraft to test the results. A luxury that we would love to have

PS - By the way, I have no problem you using my real name but can I ask what yours is?