Very nice Condor!
I have a Top Flite F4U kit that I've been tinkering with going down the heavily-modified route to fix as many of the numerous scale inaccuracies as possible. With my lack of free time lately though, I've been taking a serious look at the Hanger 9 model though. Decisions, decisions...
Haven`t heard that whistling sound on a model before, nice touch.
My sailplanes whistle very much like that, especially when they're flown fast. I'm not exactly sure why, but it's dang cool, and can be heard when the plane is 1000 feet or more above you...