Hi Gripen,
>I have the whole RAE report (RM No. 2361).
Do you happen to have it in electronic form? I'd just love to have a look at that report :-)
>The flight envelope of the Spitfire is based fully on flight tests.
That's interesting as it gives different Clmax values than the NACA report. (The impact of that difference is not as big as one would imagine since lift increases with velocity squared).
>Stall tests of the Bf 109 gives Cl 1,4 with slots power off, slots came out at Cl 0,865 (these are tested values). Power on clean 1g Clmax is calculated as 1,95 (I quess you have same graph).
I've got the graphs, and van Ishoven indeed quotes the same 1.4, which is rounded from the 1.38 I calculated from the test figures.
The 1 g clean Clmax would include extended slats, wouldn't it?
It seems NACA report "Calculated and Measured Turning Performance of a Navy F2A-3 Airplane as Affected by the Use of Flaps" applies the same method to the Brewster Buffalo.
Here's a comparison:
F2A-3 no flaps 13000 ft 900 HP: 25 s/360°
Spitfire (RAE test) 12000 ft: 19 s/360°
Me 109 (RAE test) 12000 ft: 25.5 s/360°
I was confused about which variant of Spitfire the RAE used for comparison, so I superimposed the "angle of climb" curve of Spitfire N.3171, a Mk.I with a Merlin III running at 6 1/4 lbs/sqin to the RAE graph:
Spitfire N.3171: 21.5 s/360°
(Weight of N.3171 was 6050 lbs, so I assume it didn't have pilot armour installed.)
Is it correct that Spitfire IA K.9791 was used by the RAE for the comparison? I'm not sure why it performs so much better than N.3171.
I don't think the Me 109E really had 1200 HP available, by the way. I wonder if that affected the calculations?
Regards,
Henning (HoHun)