Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Jet Engines

  1. Jan 1, 2005 #1
    thinking of a project and was wondering can a jet engine be modified to run on just hydrogen and oxygen as the fuel, or is it too explosive? if not can a pulse jet?
  2. jcsd
  3. Jan 1, 2005 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    In theory a conventional jet engine could use hydrogen, but because it is normally stored in a cryogenic storage system, there are some difficulties.

    Scramjets have been invision to run on hydrogen - no moving parts.
  4. Jan 3, 2005 #3


    User Avatar
    Science Advisor

    I think the first major thing to look at would be the amount of energy available from the ignition. Jet-A has a net heat of cumbustion of 43.2 MJ/kg. Also, H2 is not a gas that you want to play around with. Neither is pure O2 for that matter. Unless you have access to an explosion proof facility, I'd think of a different project.
  5. Jan 3, 2005 #4
    No... you can't make a jet engine run on H2/O2... it wouldn't be a jet... it would be what we like to call a "rocket".

    By definition, jets run on air... dumping a fuel and oxidizer together to combust is the definition of a rocket engine.
  6. Jan 3, 2005 #5


    User Avatar

    Staff: Mentor

    The SR-71, as originally conceived was to run on hydrogen and air. The biggest pro is, as Fred said, energy per unit mass, and the biggest con is density, not cryogenics (for the SR-71, anyway - for more mundane use, cryogenics would be an issue too). For the SR-71, cryogenics was a pro because the hydrogen could have been used to cool the airframe. The low density would have resulted in a 300 foot long plane.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook