I was working on a 300K speed triangle record out of Parowan, Utah and
had reached Richfield, some 75 miles to the North, conditions were good
and I had made the turn at Richfield airport and was at the top of a
rapid 1000 fpm average thermal at 17,000 feet when I heard or felt a
loud thud. My immediate reaction was that the water ballast had frozen
in my vertical stabilizer and blown apart. (Graham Thomson had caused
this apprehension by discussing the issue while putting anti-freeze in
his tail ballast). I moved the controls and still had control of all
surfaces and attitudes. I then looked at my right wing and saw about
a 2 foot split on the leading edge about 2 feet out. It looked as if
it were a foot wide also and I immediately dumped all water ballast and
the split reduced to no more than 1/4 inch. Stew Tittle in his LS6 and
Dale Bush in his Nimbus were close by as I announced my situation and
decision to head home. As I slowed to below 70 kts and headed home we
discussed the situation. I had reduced my performance on the computer
by 15 % and had enough altitude to make it back in my Pegasus. Dale
and Stew continued to shepherd me as I slowly made my way home. As I
arrived in the Parowan Valley and with still about 4000' over the
ground I determined to try the spoilers to see if this had any adverse
affect on the split, it didn't, I continued on to a safe landing at
Parowan and subsequent repair. Dale continued on South to the North
Rim of the Grand Canyon and return.