TheUSAirForcehasorderedthedevelopmentofahypersoniccruisemissile,whichithopeswilltravelatMach5-fivetimesthespeedofsound-throughairdefencesandkeepfighterjetpilots
Chinaisbuildingtheworld'sfastesthypersonicwindtunneltohelpwiththedevelopmentofspaceplanes."The265-meter-longtunnelcanbeusedtotesthypersonicaircraftthatcantravel
Thereareafewreasonswhyyouaren'tflyingacrossthecountryinhypersonicaircraft,butthesimplestofthemisheat:whenyoutravelatspeedsoverMach5,theultra-hightemperatures(ar