Control-Line airplanes usually have a power plant of to , although engines can be as large as .90, or may have electric power. Two-stroke glow engines are most common, but almost any form of model engine has been used, including pulse jet engines and turbojets. Control-line models tend to have very high power-to-weight ratios compared to R/C models or full-scale aircraft. The size of the engines and the models are significantly limited by the maximum line length of used for competition, although very long lines (as much as 150 feet) have been used on rare occasions.