I agree with Tiger Mate. The Whirlwind 4 and onwards had the cranked boom because of the rolling couple. The tailskid was also a lot stronger.
For those interested in the fate of various Whirlwinds I had previously posted the end of XR 478's flying career.
http://www.pprune.org/where-they-now...unky-lord.html
Last edited by Fareastdriver; 27th May 2012 at 09:21.