Alpha? 
Sorry it wasn't on my mind... butI bet I could lay down a decent one on the ice! 
www.gps-icesailing.com/default.aspx?mnu=user&val=41812&uid=122
Would be interesting to see how they jibe. A catapult would be catastrophic... but I guess waterstarts are easier and don't need an uphaul rope...
They Jibe on a dime and catapults become 30 meter "slides". We wear knee pads and a motorcycle helmet when going for world GPS records. It's actually great fun, even in light wind.
www.gps-icesailing.com/default.aspx?mnu=records
World record runs, last winter:
Big sunday 20--1-2013
www.gps-icesailing.com/default.aspx?mnu=user&val=41884&uid=55
interesting how half the field topped out at 53 knots.
I guess that is the limit of how much power the blades allow you to put down vs the drag of the rider and rig.
