The best replacement for jet engine is propeller.

The best alternatives to jet engine are rated as following:
★★★★★  propeller
★★★★  piston engine
★★★  rocket engine
★★★  turbofan
★★  turbine
★  internal combustion
★  turboprop
★  prop
★  turbine engine
  turbo prop
  turbo fan
  prop engine

Your alternative for jet engine is not listed? Suggest!
Speaking about jet engine, one probably shouldn't forget about thomas.

Other search terms related to jet engine and their ratings are:
★★★★★ thomas
thomas battery
You have in mind a companion for jet engine and it is not yet here? Propose!



Google Trends

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jet engine
propeller
piston engine