Stall speed of the Mosquito FB.VI

[Wmaker]

Doesn't a 1.1 Clmax require a thin symmetrical airfoil?  Sherf's link seems to show at least 1.35 Clmax for the same cambered RAF 34 section.

1.1 Clmax can be a result which can be arrvied to any number of ways. The link Scherf provided indeed shows higher Clmax, on the other hand the data I used shows roughly 1.1 here:

I've noticed that the Clmax figures can vary between sources for number of profiles. I think that is partly due to the fact that sometimes they are theoretically given for AoA which the profile is unable to achieve without flow separating.

The stall speed in the Pilot's Notes agrees with the data above. Two separate sources agreeing with each other and the rather big difference between the game and primary source data were the reasons why I started this thread.

[FLS]

Mossie uses the 34 mod as Scherf mentioned which I'm guessing is referring to the inner wing section. When you look at the planview the inner wing is pretty impressive and modeling the whole area as an RAF 34 section seems like it might underestimate the lift coefficient. It seems like the 1.35 in Scherf's link might be conservative depending on the radiator's effect on the airflow.

[hitech]

Wmaker that chart can not be anything from a real test, looks more like someones attempt at fluid dynamic estimation.

The reason is simple look at that chart at 8 degrees. It shows a decreasing Lift co with increasing AOA, this does not happen pre stall.

2nd

You must look very carefully at pilot notes. If it was giving an IAS (which is the most useful when flying the plane)  It does not serve much purpose in analysis with out knowing the CAS.

HiTech

[Wmaker]

Wmaker that chart can not be anything from a real test, looks more like someones attempt at fluid dynamic estimation.

The reason is simple look at that chart at 8 degrees. It shows a decreasing Lift co with increasing AOA, this does not happen pre stall.

Yeah, it definately is from some CFD software because the plot isn't smooth. What I thought it would give rather accurately is the point where the lift starts to decrease.

You must look very carefully at pilot notes. If it was giving an IAS (which is the most useful when flying the plane)  It does not serve much purpose in analysis with out knowing the CAS.

Good point. The speed measurement most probably isn't entirely accurate but it is good for the pilot to know what speedo indicates as the aircraft stalls. The AoA between the pitot tube and the incoming airflow probably can increase this error even further (That error is also modelled into game, though).





Some Mosquito stall speeds from a book about the war time history of Boscombe Down (British flight testing establishment):

It does not mention wheather these were IAS or calibrated.

W4050 (Prototype, Feb '41) flown with "modest weights"
105mph, clean
90mph, landing config
(considered high at the time)

DZ594/G, 17650lbs
115mph, clean
100-105mph, landing config.

PR.XVI: DZ540, 22300lbs
132mph, clean
118mph, landing config.

MK.XIV: ML937, 25279lbs (Cookie onboard)
143mph, clean

[Letalis]

What is the normal range for WWII aircraft in terms of lift co?

For production U.S. fighters the coefficient range was roughly 1.4-2.5 iirc.

[Charge]

"The reason is simple look at that chart at 8 degrees. It shows a decreasing Lift co with increasing AOA, this does not happen pre stall."

Assuming RAF34 resembles NACA 63-412 at abt. 8 degrees the profile comes out of "low drag bucket" (which is similar to that of P-51 due to symmetry of the leading edge) where the lift does not increase but there is a somewhat sharp rise in profile drag and I assume that is what is seen in the figure.

-C+