Ten real aircraft engines: Wright 1903, Gnome Omega, Liberty L-12, Rolls-Royce Merlin, Pratt & Whitney R-2800, Jumo 004, BMW 003, Whittle W.1, GE J47, and Pratt & Whitney JT3D. Photograph credits: 1. File:Wright 1903 engine-Smithsonian-01.jpg; Smithsonian Institution; Public domain; https://commons.wikimedia.org/wiki/File:Wright_1903_engine-Smithsonian-01.jpg; https://commons.wikimedia.org/wiki/File:Wright_1903_engine-Smithsonian-01.jpg; 2. File:Gnome Omega (MAE).jpg; Duch.seb; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0; https://commons.wikimedia.org/wiki/File:Gnome_Omega_(MAE).jpg; 3. File:Liberty Aircraft Engine Number 1.JPG; Wikimedia Commons contributor; Public domain; https://commons.wikimedia.org/wiki/File:Liberty_Aircraft_Engine_Number_1.JPG; https://commons.wikimedia.org/wiki/File:Liberty_Aircraft_Engine_Number_1.JPG; 4. File:Rolls-Royce Merlin.jpg; JAW at English Wikipedia; CC BY-SA 3.0; http://creativecommons.org/licenses/by-sa/3.0/; https://commons.wikimedia.org/wiki/File:Rolls-Royce_Merlin.jpg; 5. File:Pratt & Whitney R-2800 Engine 1.jpg; Highflier; CC BY-SA 3.0; http://creativecommons.org/licenses/by-sa/3.0/; https://commons.wikimedia.org/wiki/File:Pratt_&_Whitney_R-2800_Engine_1.jpg; 6. File:Motoreattore Junkers Jumo 004.jpg; Pigr8; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0; https://commons.wikimedia.org/wiki/File:Motoreattore_Junkers_Jumo_004.jpg; 7. File:BMW 003 jet engine.JPG; MisterBee1966 ( talk ); Public domain; https://commons.wikimedia.org/wiki/File:BMW_003_jet_engine.JPG; https://commons.wikimedia.org/wiki/File:BMW_003_jet_engine.JPG; 8. File:Whittle W.1X NASM.jpg; Dane A. Penland; CC0; http://creativecommons.org/publicdomain/zero/1.0/deed.en; https://commons.wikimedia.org/wiki/File:Whittle_W.1X_NASM.jpg; 9. File:General Electric J47-GE-17B, Museo dell'aria e dello spazio (San Pelagio, Due Carrare).JPG; Threecharlie; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0; https://commons.wikimedia.org/wiki/File:General_Electric_J47-GE-17B,_Museo_dell'aria_e_dello_spazio_(San_Pelagio,_Due_Carrare).JPG; 10. File:Pratt & Whitney JT3D turbofan engine, 1958 - Evergreen Aviation & Space Museum - McMinnville, Oregon - DSC00877.jpg; Daderot; CC0; http://creativecommons.org/publicdomain/zero/1.0/deed.en; https://commons.wikimedia.org/wiki/File:Pratt_&_Whitney_JT3D_turbofan_engine,_1958_-_Evergreen_Aviation_&_Space_Museum_-_McMinnville,_Oregon_-_DSC00877.jpg;