▁traditional ▁field ▁of ▁performance ▁testing ▁and ▁the ▁relatively ▁new ▁field ▁of ▁stability ▁and ▁control , ▁which ▁had ▁suddenly ▁assumed ▁critical ▁importance ▁with ▁the ▁dram atic ▁increases ▁in ▁speed ▁offered ▁by ▁the ▁new ▁tur bo jets . ▁As ▁the ▁de cade ▁opened , ▁the ▁first - gener ation ▁X - 1 ▁reached ▁ ▁and ▁a ▁ ▁alt itude , ▁representing ▁the ▁edge ▁of ▁the ▁en velope . ▁The ▁D - 5 5 8 - II ▁Douglas ▁Sky ro cket ▁soon ▁sur pass ed ▁these ▁marks . ▁In ▁ 1 9 5 1 , ▁Douglas ▁test ▁pilot ▁Bill ▁Br id g eman ▁fle w ▁the ▁Sky ro cket ▁to ▁a ▁top ▁speed ▁of ▁ ▁and ▁a ▁peak ▁alt itude ▁of ▁. ▁Then , ▁in ▁ 1 9 5 3 , ▁Marine ▁Corps ▁test ▁pilot , ▁Lieutenant ▁Colonel ▁Mar ion ▁Carl , ▁fle w ▁the ▁same ▁plane ▁to ▁an ▁alt itude ▁of ▁. ▁ ▁On ▁ 2 0 ▁November ▁ 1 9 5 1 , ▁the ▁National ▁Ad vis ory ▁Committee ▁for ▁Aer onaut ics ' ▁Scott ▁Cross field ▁became ▁the ▁first ▁man ▁to ▁reach ▁Mach ▁ 2 ▁as ▁he ▁pil oted ▁the ▁Sky ro cket ▁to ▁a ▁speed ▁of ▁. ▁Less ▁than ▁a ▁month ▁later , ▁Major ▁Ch uck ▁Ye ager ▁to pped ▁this ▁record ▁as ▁he ▁pil oted ▁the ▁second - gener ation ▁Bell ▁X - 1 A ▁to ▁a ▁top ▁speed ▁of ▁ ▁and , ▁just ▁nine ▁months ▁later , ▁Major ▁Arthur ▁" Kit " ▁Murray ▁fle w ▁the ▁same ▁air plane ▁to