|This looks like possibly the same aircraft (the BuNo isn't visible due to the angle)|
on a day when it was been flown clean-winged.
Tuesday, September 4, 2012
and available here on the web), indeed suggest a test role.
The F9F Cougar was an update to the earlier F9F Panther, which had been out-classed by the MiG-15 in Korea, in which the Panther's straight wing and tail were replaced with swept wing and horizontal, giving the aircraft a higher critical Mach number, and thus a higher top speed (although it was still a sub-sonic aircraft). Initial production of the Cougar started with the F9F-6 in 1952. The -8 was the final mass-produced version, and incorporated an 8-inch fuselage stretch and wings with a larger chord and a cambered leading edge for better low-speed capabilities.