"Big John" wrote in message
...

Remember the X-15 dropped the rudder off to land. This would have
disqualified them


How would that have been disqualifying? The X-15 dropped the rudder portion
of the ventral fin in order to gain sufficient clearance for the landing
skids. The rudder was not discarded, it returned by parachute and was
reused. The X Prize rules require the vehicle to return from both flights
substantially intact such that the vehicle is reusable, and that no more
than 10% of the flight vehicle's first-flight non-propellant mass be
replaced between the two flights. The X-15's lower rudder was reusable, but
even if it was discarded each flight it was obviously far less than 10% of
the X-15's 11,374 lb. empty weight.