Build Your Own Motorized Jet Engine This officially licensed Smithsonian Test Jet Engine Model Kit educates anyone who’s interested in how actual jet engines operate. Learn the basic engine definitions such as: combustion chamber, shaft, thrust, turbojet, and turboprop. When your engine is built, you can control thrust and the turbine speed with realistic engine sounds. Kit comes with more than 50 parts; requires four AA batteries and simple assembly. Measures about 8”l x 12”w x 7.5”h. Recommended for ages 8 and up.