Is steam or air really viable?

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Aerowerx, Jul 17, 2019.

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  1. Jul 19, 2019 #21

    BBerson

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    Steam has advantages also. For one, you can sit at the end of the runway for several minutes and build up a huge store of steam energy. So your steam generator would only need to be 50% as large, if you want to cruise at 50% power. A huge excess of power for a minute of climb at takeoff.
    I would look at a steam turbine. Much lighter, no complex compressor or exotic metals of a gas turbine.
     
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  2. Jul 19, 2019 #22

    proppastie

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    I wounder if the temperatures could be kept down with steam, (lower pressure at the turbine) (maybe still high pressure/heat in the tank) in such a way as to use CF ....a true plastic engine.
     
  3. Jul 19, 2019 #23

    BBerson

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  4. Jul 20, 2019 #24

    Aerowerx

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    Would not the problem be with the Resin used to bind the carbon fibres together? The carbon itself would not be affected, I would think.
     
  5. Jul 20, 2019 #25

    proppastie

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    Yes the resin certainly is the problem...there are high temperature mixes, but none as high as aluminum and certainly not steel....reason we do not have plastic engines yet.
     
  6. Jul 20, 2019 #26

    proppastie

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    is superheated steam hard on valves or regulators for controlling the speed?
     
  7. Jul 20, 2019 #27

    pictsidhe

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    And the range of that steam ricket was what, 1/2 mile?
     
  8. Jul 20, 2019 #28

    BBerson

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    I don't have any experience. Just read some about marine auxiliary steam turbines.
     
  9. Jul 20, 2019 #29

    BJC

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    Assuming that the valve material is adequate for the temperature, superheated steam that stays superheated as the pressure drops is not very erosive. Saturated steam will rapidly erode throttling valve seats, plugs and bodies.


    BJC
     
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  10. Jul 20, 2019 #30

    poormansairforce

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    Super heated steam makes lubrication much more difficult.
     
  11. Jul 20, 2019 #31

    BJC

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    What is it about superheated steam that makes lubrication more difficult? I would think just the opposite; it would be easier to lubricate a machine whose operating fluid was a dry gas.

    Saturated steam (i.e., not superheated) is possible up to 3,200 psia at 705 degrees F.


    BJC
     
  12. Jul 20, 2019 #32

    poormansairforce

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    Oils tend to vaporize at those temperatures so oil needs to be point injected at every individual location to ensure there is time for it to do its job. It will depend on the temps and type of application. Turbines will be easier than engines.
     
  13. Jul 20, 2019 #33

    proppastie

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    Is that the low cutoff temperature/pressure for steam engine/turbine? In other words, add more heat, and/or close the valve.
     
  14. Jul 20, 2019 #34

    mm4440

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    Hi, there were many steam projects for cars in the 1970's for smog reasons. They were built and tested. The conclusion was ; Too expensive. Too heavy. Usable but lower efficiency. For aircraft, there have been projects but only one documented successful, Bill Besler's in 1933. It is being experimented with as a bottoming cycle for cars to make use of energy in exhaust heat that is now waisted, better for trucks than cars. For very long endurance aircraft, it might be worth the extra weight and cost. It is possible to build a small system to fly a motorglider type aircraft to prove that it is possible.
     
  15. Jul 20, 2019 #35

    jedi

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    So I conclude the steam engine is great, even better than the electric motor, providing we eliminate the condenser, boiler and high temperatures of the water/steam. Also eliminate the heavy piston cylinder and crankshaft. That is where the effort should be focused. I am working on that.
     
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  16. Jul 20, 2019 #36

    Aerowerx

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    IIRC, one advantage of a piston type steam engine is that it can develop full torque at 0.0 RPM, unlike a gasoline engine. That may be an advantage for a steam locomotive, but not for an aircraft where you want full torque at take-off RPM. What is the torque curve like for a steam turbine?
     
  17. Jul 20, 2019 #37

    Aerowerx

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    So it is great if we eliminate every thing about it that we don't like??o_O
     
  18. Jul 20, 2019 #38

    poormansairforce

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    The fuel...you forgot to eliminate the fuel! Tree huggers will love that!
     
  19. Jul 20, 2019 #39

    BJC

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    The point is that superheated steam can have almost any temperature from the low 100’s on up. At standard conditions, steam at 213 degrees F would be superheated, by 1 degree.

    Typical electric utility steam turbines use main (high pressure) steam temperatures around 1,005 degrees F, and reheat steam (much lower pressure) also of 1,005 degrees F. Saying “superheated” says nothing about the temperature.

    Cooling the lube oil for a stationary steam turbine is not difficult. I have no experience with piston steam engines.


    BJC
     
  20. Jul 20, 2019 #40

    BJC

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    That point is known as the critical point. Above that point there is no phase change between steam and water; it just is H2O with more energy.


    BJC

    edit. Deleted incorrect reference to triple point.
     
    Last edited: Jul 21, 2019
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