Thanks, I wondered if it had been outed rather than discovered. It must have been known about if you could buy models, let alone have anyone wonder what was in those sheds, but I guess the other side had as much to gain by keeping it quiet, as did the US. I thought it may have been released at that time as a sort of coup de grace.. something to make the Soviets realise that they could never hope to catch the US up and that resistance (financial at least) was futile.
I noticed too, that some of the crashes (pro rata, more than you might expect?) were caused by spatial disorientation - the result of limited visibility from the seat?