Gas turbine on and off to run it only at high efficiency. The emergence of the continuously variable transmission may also alleviate the responsiveness problem. Turbines have historically been more expensive to produce than piston engines, though this is partly because piston engines have been mass-produced in huge quantities for decades, while small gas turbine engines are rarities; however, turbines are mass-produced in the closely related form of the turbocharger. The turbocharger is basically a compact and simple free shaft radial gas turbine which is driven by the piston engine's exhaust gas. The centripetal turbine wheel drives a centrifugal compressor wheel through
Fastest propeller-driven aircraft of gas turbine configured such that most of the work available results from the thrust of the hot exhaust gases. Turbofans, both the high-bypass versions used in all modern commercial jetliners, and the low-bypass versions in most modern military aircraft, produce a combination of jet thrust from the exhaust of burnt fuel, and air thrust from what amounts to an internal propeller. High-bypass turbofan engines achieve most of their thrust from a fan driving air backwards through the engine casing, and driven by a gas turbine, which also contributes jet thrust via its exhaust. The two are in one large