An unpowered vehicle, ya bilge rat, with t' same aerodynamic characteristics as a rocket. Well, blow me down! Blimey! A dart is one method o' propellin' a payload package t' a maximum altitude. T' dart rides on top o' a large booster, arrr, possessin' a higher coefficient o' drag. Durin' powered flight t' dart acquires all t' momentum o' t' entire vehicle. As t' booster begins t' slow durin' t' coastin' phase, matey, its greater drag causes it t' fall away from t' dart which continues t' ascend t' a higher altitude.