Stability and Control characteristics of the Early Mark Spitfires

[MiG-3U]

Ok, one more as I've been asked how to do the CoG calculation.

The dimensions can be found from the AB197 graph:

http://www.spitfireperformance.com/ab197datum.gif

and from page seven of the RM2535:

http://aerade.cranfield.ac.uk/ara/dl...rc/rm/2535.pdf

Lenght of aerodynamical mean chord (MAC): 78.54"
Location of datum line: 18.65" behind leading edge at MAC
Aft limit at MAC: 34% 26.7036" behind leading edge
Aft limit at wing root: 2.638' = 31.656" behind leading edge
CoG used by NACA: 31.4" behind leading edge at wing root

The rest is simple math:
Aft limit behind datum line at MAC: 26.7036" - 18.65" = 8.05"
Datum line behind leading edge at wing root: 31.656" - 8.05" = 23.6024"
NACA CoG behind datum line: 31.4" - 23.6024" = 7.7976"
NACA CoG location at MAC behind leading edge: 18.65" + 7.7976" = 26.4476"
NACA CoG % at MAC: 26.4476" / 78.54 * 100 = 33.6741%

Over and out.