1 6 ▁April ▁ 1 9 5 7 , ▁this ▁was ▁followed ▁by ▁the ▁first ▁installed ▁ground ▁run ▁of ▁its ▁Vi per ▁engine . ▁On ▁ 9 ▁May ▁ 1 9 5 7 , ▁X D 1 4 5 ▁conducted ▁the ▁type ' s ▁first ▁ground ▁tax i ing ▁trial . ▁ ▁On ▁ 1 6 ▁May ▁ 1 9 5 7 , ▁Squadron ▁Le ader ▁John ▁Bo oth ▁D FC ▁was ▁at ▁the ▁controls ▁of ▁X D 1 4 5 ▁for ▁the ▁first ▁test ▁flight , ▁following ▁up ▁with ▁the ▁ma iden ▁flight ▁of ▁the ▁second ▁prototype ▁X D 1 5 1 , ▁on ▁ 6 ▁December ▁ 1 9 5 7 . ▁Test ▁results ▁indicated ▁"... an ▁extremely ▁do cile ▁and ▁exceed ingly ▁pleasant ▁aircraft ▁to ▁fly , ▁with ▁very ▁well ▁harm on ized ▁controls ". ▁Both ▁pro tot ypes ▁fle w ▁a ▁total ▁of ▁ 5 6 ▁test ▁fl ights , ▁with ▁Mach ▁ 1 . 3 3 ▁spe eds ▁being ▁obtained . ▁ ▁While ▁testing ▁at ▁R AE ▁Bos com be ▁Down , ▁X D 1 5 1 ▁crash ed ▁on ▁ 5 ▁June ▁ 1 9 5 8 ▁during ▁an ▁ab orted ▁take off ▁on ▁its ▁ 1 2 th ▁flight . ▁Running ▁off ▁the ▁run way , ▁the ▁aircraft ▁struck ▁a ▁concrete ▁approach ▁light , ▁expl oding ▁on ▁impact ▁and ▁killing ▁its ▁pilot , ▁Squadron ▁Le ader ▁Bo oth . ▁The ▁remaining ▁prototype ▁continued ▁to ▁fly ▁with ▁L t ▁C dr ▁Peter ▁Lamb ▁taking ▁over ▁the ▁flight