THE SAILPLANE WAS FOUND IN A NOSE DOWN ATTITUDE AMOUNG 10 TO 15 FOOT RIBBON-WOOD SHRUBS APPROX 250 FT WNW OF THE DEPARTURE END OF A SMALL AIRSTRIP. BOTH WINGS WERE FOUND DISPLACED FORWARD WITH THE RT ONE FORMING A STRAIGHT LINE EXTENSION FORWARD FM THE FUSELAGE. NO WITNESSES WERE FOUND THAT OBSERVED THE ACCIDENT. THE PLT HAD BEEN ATTEMPTING A 5 HOUR DURATION FLT WITH THE POSSIBILITY OF FLYING OUR 300 MILES TO QUALIFY FOR A DISTANCE AWARD. TRANSMISSIONS TO THE CO-OWNER ON THE GROUND INDICATED HE WAS HAVING TROUBLE MAINTAINING ALT AND HIS ORTENTATION TO HIS PLANNED COURSE. HIS LAST TRANSMISSION STATED THAT HE HAD BEEN MISTAKEN ABOUT HIS PRIOR LOCATION AND THAT HE HAD TO DUMP HIS BALLAST. A BAROGRAPH WAS FOUND IN THE ACFT WHICH INDICATED OUR 2 HOURS OF FLT TIME WITH AT LEAST 2 LOSSES OF ALT BFR THE FINAL DECREASE. IN ADDITION THE LAST ALT DECREASE WAS PRECEEDED BY A SLIGHT INCREASE IN ALT FOLLOWED BY WHAT APPEARS TO BE A RAPID DECREASE.