THE HOME BUILT ACFT WAS OF THE PLT'S OWN DESIGN. IT WAS A 4 PLACE, LOW WING ACFT WITH A LARGE CANOPY & SMALLER VERT TAIL SURFACES AND WAS EQUIPPED WITH FLAPS, FOLDING WINGS & FIXED TAIL WHL GEAR. THE PLT/DESIGNER WAS TRYING A NEW CONCEPT OF LATERAL CONTROL BY USING "ROLLERONS" INSTEAD OF CONVENTIONAL AILERONS. THEY OPERATED SOMEWHAT LIKE SPOILERS ON A GLIDER. THE ROLLERONS WERE 2 FT LONG, 6 IN WIDE, INSTLD ON THE TOP & BOTTOM OF EACH WING AT THE TIPS. FOR A RGT TURN, THE RGT TOP ROLLERON WOULD MOVE UP 8 THE LFT BOTTOM WOULD MOVE DWN WHILE THE OTR 2 RMND IMMOBILE. FOR A HI SPD TAXI TEST, THE RUDDER & ELEVATORS WERE TUFTED WITH YARN TO SHOW AIRFLOW & AN ASSOCIATE FLWD TO OBSV. HE RPRTD THAT THE ACFT BCM AIRBORNE, VEERED OFF THE RWY, WENT DWN A STEEP EMBANKMENT, THEN CRASHED & BURNED. ANOTHER ASSOCIATE OF THE PLT RPRTD THAT WHEN HE TAXIED THE ACFT AT HI SPD, IT FELT LIKE IT WAS CROSS-CONTROLLED & THERE WAS A "DEAD SPOT" WHEN THE "ROLLERON" CONTROL WAS AT THE NEUTRAL POSITION.