Editing Model aircraft (section)

====Compressed gases====
Stored compressed gas, typically [[carbon dioxide]] (CO<sub>2</sub>), can power simple models in a manner similar to filling a balloon and then releasing it. Compressed CO<sub>2</sub> may also be used to power an expansion engine to turn a [[propeller (aircraft)|propeller]]. These engines can incorporate speed controls and multiple cylinders, and are capable of powering lightweight scale [[radio-controlled aircraft]]. Gasparin and Modela are two recent makers of CO<sub>2</sub> engines. CO<sub>2</sub>, like rubber, is known as "cold" power because it generates no heat.

Steam is even older than rubber power, and like rubber, contributed much to [[history of aviation|aviation history]], but is now rarely used. In 1848, [[John Stringfellow]] flew a steam-powered model, in [[Chard, Somerset]], [[England]]. [[Samuel Pierpont Langley]] built both steam- and internal-combustion-powered models that made long{{quantify|date=December 2022}} flights.

Baronet Sir [[George Cayley]] built, and flew, internal and external combustion [[gunpowder]]-fueled model aircraft engines in 1807, 1819, and 1850. These had no crank, working [[ornithopter]]-like flappers instead of a propeller. He speculated that the fuel might be too dangerous for manned aircraft.