Editing Ramjet (section)

===Performance and control===
Although ramjets have been run as slow as {{convert|45|m/s|km/h mph}},<ref name="primer">[http://www.alt-accel.com/ramjet2.htm Ramjet Primer].</ref> below about {{convert|0.5|Mach|m/s km/h mph|sigfig=2}} they give little thrust and are highly inefficient due to their low pressure ratios.

Above this speed, given sufficient initial flight velocity, a ramjet is self-sustaining. Unless the vehicle [[drag (physics)|drag]] is extremely high, the engine/airframe combination tends to accelerate to higher and higher flight speeds, substantially increasing the air intake temperature. As this could damage the engine and/or airframe integrity, the fuel control system must reduce fuel flow to stabilize speed and, thereby, air intake temperature.

Due to the stoichiometric combustion temperature, efficiency is usually good at high speeds (around {{convert|2|-|3|Mach|m/s km/h mph|disp=comma|sigfig=2}}), whereas at low speeds the relatively low pressure means the ramjets are outperformed by [[turbojet]]s and [[rocket]]s.