At least one report mentions a "crosswind" and the glider being "flipped upside-down". This seems extremely unlikely and is probably the opinion of an untrained eye. I'm sure the thorough investigation that will be done will show the actual cause, but that may take some time.
The last time I talked to Dan in person was at the Reno Air Races. He was a great ambassador for our sport and just an all-around great guy. The only site I remember flying with Dan was at Hat Creek many years ago.
A spectator at the Idaho show was filming an F-22 taxiing and catches Dan in the background on what looks to me like his final approach. I didn't see anything unusual but Dan is well off in the distance. The crash is not captured. You have to scroll down to see the footage here: http://www.ibtimes.com/idaho-air-show-d ... sh-2686764
First glider was a 19' EipperFormance Standard Rogallo bought as a kit in 1974 for about $400.00.