Flight speed Ramjets generally give little or no thrust below about half the speed of sound, and they are inefficient (specific impulse of less than 600 seconds) until the airspeed exceeds due to low compression ratios.
Flight speed Ramjets generally give little or no thrust below about half the s,peed of sound and they are inefficient (specific impulse of less than 600 seconds) until the airspeed exceeds due to low compression ratios.