One of the things to keep in mind when it comes to how an airplane’s engines work is that there are numerous sizes. According to StartPac, the first thing a plane owner must do is determine how much power they need to keep a plane’s electrics on both during takeoff and flight. You can usually find this information in the plane’s manual, or by inspecting the plane’s electrical system closely.
A 28 volt battery pack is a fairly common type of pack for a consumer plane, and it provides the energy that is needed to get the engines to start to turn over. Hot gases are also produced that will transfer energy to the engines. It’s similar to the concept of a windmill. There is a shaft located inside the engines that will begin to turn, and once there is enough speed, then the engines will work.
There is often an electric component that assists the turbine starting process. This motor is located on the outside of the engine. It will spin the main shaft until there is a sufficient amount of air that can keep the compressor and combustion chamber operational. Fuel will then start to flow through the system, giving the power to the engine to work.
Once the engine is operating, the plane can begin to move on the tarmac in preparation for taking off. A portable power supply can be taken onto the plane, such as a Red Box, but it’s more common to see them on the tarmac. Helicopters often use portable PSUs to provide power to craft in an area that is difficult to maneuver through.