Steam turbine ducted fan racing aircraft

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by novice, Feb 9, 2019.

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  1. Feb 9, 2019 #1

    novice

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    In 1950s there were several attempts to design steam turbine jet aircrafts:

    https://digital.library.unt.edu/ark:/67531/metadc58164/m2/1/high_res_d/19930085809.pdf
    https://digital.library.unt.edu/ark:/67531/metadc52887/m2/1/high_res_d/19630003317.pdf
    http://hdl.handle.net/2060/19690030675


    Here is a calculation of the steam jet engine aircraft from the 1952 study "Basic performance characteristics of the steam turbine-compressor-jet aircraft cycle" by A. Fraas and G.Cohen. Results are showing that this concept is feasible.


    I wonder if it is possible to build racing aircraft with the steam turbine driven ducted fan and high temperature steam condenser?
     

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  2. Feb 9, 2019 #2

    Aesquire

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    Sure. And you can save all the boiler and condenser and turbine nonsense & go straight to rocket power.

    https://en.m.wikipedia.org/wiki/Nuclear_salt-water_rocket

    Now, you want to race these on a planet you don't ever plan to colonize, or between planets, where the solar wind carries away the waste products. Certainty not at Reno,or anywhere in our atmosphere.

    Oh, and the problems of passing, closer than a few miles is deadly, and you can't watch the race with your naked eyes.....

    And if you thought 100LL was expensive fuel......

    In that context, steam turbine race planes just needs some engineering to be practical. Like injecting anti matter into the boiler for the quick start.

    Or is my thinking too ambitious? ;)
     
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  3. Feb 9, 2019 #3

    Aesquire

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    https://en.m.wikipedia.org/wiki/Project_Pluto

    Actual, tested, hardware. Never flight tested because of an outbreak of sanity. Certainly not as efficient as a phase change (steam) system, but much lighter.

    It was noted that it wasn't needed to arm the SLAM. ( best, acronym, Ever! ) It's design flight mode, to avoid intercept, was Mach 3 on the deck.

    So the first thing you know about it arriving at your farm is the shock wave knocking all the buildings down, then the exhaust sets fire to the chickens & flying debris. It literally leaves a line of flaming destruction behind along the entire flight path. Best viewed from orbit.

    No more waiting at the pylons at Reno to get a great view. Well, ok, once.



    In context to the real thing, steam turbine racers seem kinda practical.
     
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  4. Feb 9, 2019 #4

    novice

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    Rolls Royce is building the fastest racing electric aircraft with only 200 miles range:
    https://www.rolls-royce.com/media/our-stories/innovation/2018/introducing-accel.aspx
    https://www.rolls-royce.com/~/media...ltrafan/Rolls_Royce_IG_Final_04_RGB_Sheet.pdf

    Steam cycle jet engine will have overall efficiency between 10-20 percents depending on ambient temperature and aircraft flying speed.
    Jet fuel energy density is very high and is not a limiting factor. The jet airplanes described in these papers were designed to fly at 40,000 ft at Mach 0.9 - 600 mph.
    The dimensions and weight of the steam compressor jet cycle at this conditions are larger than of turbojets but less than IC engines. IC engines aircrafts are not able to fly faster than Mach 0.7 anyway. At 600 mph engine producing 1000 pound of jet thrust has design weight 700-1000 pounds with the condenser, steam turbine, gearbox, air fan and steam condenser, but without steam generator and water.

    The main problem with the steam cycle is extremely heavy and large steam condenser. Using backpressure 5000 psi/1000F supercritical steam turbine allows to obtain relatively high efficiency between 15 to 20 percent and to condense exhaust steam at pressures 400-1200 psi and 450-550 F.



    Water does not boil at 5000 psi at any working temperature , but only expands in volume approximately 2.5-3 times without steam bubbles formation. "Steam" generator has relatively light weight and is very compact.
     

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    Last edited: Feb 9, 2019
  5. Feb 9, 2019 #5

    BoKu

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    Just so everyone is clear on this, the charts and diagrams do not depict a "steam powered" airplane. What they demonstrate is the feasibility of an aircraft powered by a nuclear fission reactor that happens to use superheated steam to deliver power from the reactor to a ducted fan. In the absence of the kind of power- and energy density you get from a fission reactor, it's almost certainly a non-starter. You'd be much better off using your heat source to expand air directly into a turbine as in a conventional jet engine, and skip the heavy and inefficient abstraction of the steam cycle.
     
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  6. Feb 9, 2019 #6

    rv6ejguy

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    Nobody will ever do this for a Reno racer since efficiencies are about half of an IC engine and weight would be much higher, not to mention the complexity and cost of building the custom turbine, boiler and condensor. I don't see how you could generate the heat required in a small space like this combusting gasoline or Jet A either.
     
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  7. Feb 9, 2019 #7

    mcrae0104

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    A fission class sure would be fun. Instead of gold, silver, and bronze, maybe they could divide the heats into uranium, plutonium, and thorium.
     
  8. Feb 9, 2019 #8

    Aesquire

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    Thorium for endurance. Much better efficiency.

    Go straight to my first post for speed. There is the little matter of exhaust and that continuous fission explosion just behind the engine. So, not for Reno. Mons Olympus course, maybe.

    The short course would be, start in Earth orbit, Luna is the pylon turn, return to Earth orbit.

    Long course is start at L5 station, around Venus, return to L5. Endurance course has a slingshot turn inside Saturn's rings.

    The steam business is for B-36 sized planes. LA to D.C. & return laps.
     
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  9. Feb 9, 2019 #9

    novice

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    Steam cycle can use any source of heat including fission energy.

    But the question was only about technical feasibility of short range high speed steam compressor jet aircraft with the water boiler heated by jet fuel combustion.


    Reno air racers carry a limited amout of fuel - 100-300 gallons and fly for a very limited time, usually less than 30 minutes:

    http://www.bluethunderairracing.com/the-plane/specifications/

    If steam cycle efficiency is only 10 percent and propulsive power is 2000 hp, than the jet fuel consumption will be 400 gallons per hour. So only dimensions and weight of such system can be a limiting factor.
     
  10. Feb 9, 2019 #10

    TFF

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    The actual answer is no. The boys who make the rules and run the shows don't care. Speed is not important like it was in the 1930s. You can buy fast any day of the week. Racing is not a good technology showcase any more either. So no.
     
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  11. Feb 9, 2019 #11

    rv6ejguy

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    No class exists for it at Reno and RARA isn't going to make a new one for one guy even if you built the plane and showed it could work. It's just dreaming. Nobody is going to build this plane. It would cost many hundreds of thousands or millions of dollars to even build a proof of concept aircraft with this power source using an existing aircraft. Squeeze all this gear into a small racer would be even more challenging. Never going to happen for a hundred reasons.

    I'd be very surprised if you could create the energy release rates to make 2000 SHP and fit in something the size of a Thunder Mustang.
     
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  12. Feb 9, 2019 #12

    novice

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    Reno air racing is a great show:

    https://youtu.be/r00SaRYm3Rc

    Planes fly eight laps, total 64 miles. That's a very short
    distance.
    Any project like this will cost a lot.

    Electric airplanes have very small energy storage and can fly for a very short time, yet there is a great interest in electric air racing.

    The parameters of the Pratt and Whitney steam aircraft engine are quite impressive:
    Low level cruising speed - mach 0.9, 685 mph.
    Air fan diameter - 117 in, 2110 rpm.
    Steam turbine -49100 hp, 20000 rmp, 3200 lbs.
    Gear box ratio1/9.5, weight 5000 lbs
    Steam turbine intake pressure 5000 psi at 981F
    Steam exhaust-423 psi at 450 F.
    Steam condenser is 13.1 ft in diameter and 18.9 ft long. Its weight is approximately 6,000 lbs.
    Condensate flow is 214 lbs/s.
    Condensate pump turbine is 7930 hp and is receiving steam from the main turbine exhaust.
    Air flow 3300 lbs/s
    Jet exhaust velocity- 1280 ft/s
    Thermal power consumed by a steam generator is 410 megawatt, each engine receives half of that amout.
    This is approximately equivalent of 84,000 lbs of jet fuel per hour at 90% boiler efficiency.
    Jet thrust of each engine is 28,260 lbs, net propulsive power is 2×51,560 hp.

    Aircraft design weight was 300,000 lbs.
     
  13. Feb 9, 2019 #13

    mcrae0104

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    BoKu answered this. It is more efficient to burn the fuel, expand some gasses, and squirt them out the back. I believe the scheme you're suggesting is to burn some fuel, transfer that heat to water to turn it into steam, then use that steam to turn a turbine, then use that turbine to turn a propeller.

    The problem is twofold: one, each step in this chain loses efficiency (like a stock that loses 5% per year, you'll be close to broke pretty quick); two, that's a lot of extra weight to carry around.

    The only reason to introduce steam into the middle of the picture is that you can't turn fission directly into propulsion quite so conveniently as you can with a gas turbine. The steam is just an intermediary to make the nuclear reaction useful for something other than creating raw heat.
     
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  14. Feb 9, 2019 #14

    BBerson

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    Could work with a fuel fired flash boiler and no condenser for a short flight. Just exhaust the spent steam.
     
  15. Feb 10, 2019 #15

    Jimstix

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    You want a steam powered Reno Racer? The easier, cheaper, and (maybe) safer way is to dispense with the whole reactor approach and stick with good old-fashioned chemistry. More particularly German chemistry – Concentrated Hydrogen Peroxide, aka High-Test Peroxide (HTP) and a water-soluble catalyst like Sodium Permanganate. You should avoid trying to condense the steam mixture, just expand the high-pressure steam and dump it overboard in a manner acceptable to the rules committee (jet thrust may not be allowed). Just follow the steps below.

    Design and build the propeller, gearbox, power-plant, and fuel load to run at full-power (4000 to 8000 SHP?) AND an airframe that has a higher critical Mach number than any of the Reno warbirds. The fuel load must last just long enough to taxi, takeoff, loiter, race, and land. A 9-g airframe and a good pair of speed jeans will also be required. That is all there is to it!
     
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  16. Feb 10, 2019 #16

    Aesquire

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    The key word here is "conveniently".

    I disagree, it's harder to have less mechanism than a heat source you pass reaction fluid through. See the Pluto project. Other than the control surfaces, and the control rods in the reactor, there aren't any moving parts except air. No pumps, no turbines, no fuel tanks.

    The downside of the SLAM was the selection of a graphite reactor, ( cheap,disposable ) similar to the old NERVA. https://en.wikipedia.org/wiki/NERVA If the tungsten design used in DUMBO was instead used the exhaust might have been clean enough for actual commercial use.

    https://web.archive.org/web/20120204044749/http://www.dunnspace.com/00339489.pdf

    The biggest problem with SLAM was the exhaust had hot, radioactive carbon spraying out of it as the core disintegrated under the fast moving air stream & high temperatures. For a disposable cruise missile, this made sense... in a crazy way... After all, in a world where there are going to be hundreds of H-bombs going off, a little radioactive exhaust was no big deal. And if it reduced the number of bombs turning cities into radioactive pyres, it was a planetary plus.

    I'll skip the politics of the Cold War and MAD because we don't do politics here. The technology has no politics or believe system, it's just technology.

    The OP is trolling, or honestly doesn't get that the energy density required to make steam practical in this context requires anti matter or fission. ( Fusion, would be better, but that's not available this week)
     
    Last edited: Feb 10, 2019
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  17. Feb 10, 2019 #17

    Aesquire

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    Since the airline profits are nearly 100% determined by fuel to passenger costs, ( everything else is fixed costs, or they quit giving it to you for free ) Nigh unlimited range atomic ramjets would be used with glee. If they were available.
     
  18. Feb 10, 2019 #18

    TFF

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    There is a British Sea Harrier on Barnstormers. It would be much less expensive to buy and operate and you get to be one of the cool kids. L-29 or 39 are down right cheap for an entry to jet ownership. Something like you want you need to be a Musk where you don't ask if it's cool to do, you just do it possibly making it cool. You state no need or advantage to the technology over something else. Because it exists and no one is all over it shows either no understanding or does show understanding.
     
  19. Feb 10, 2019 #19

    pictsidhe

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    Not feasible with a condensor, they are just too heavy. Using Jimstix's chemical approach is the only real way to make this work.With a turbine on the end of a peroxide rocket, you'll get much higher efficiency at subsonic speeds. The German rockets did have that annoying tendency to explode that you may want to address.
     
  20. Feb 10, 2019 #20

    mcrae0104

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    Yeah, that's not what's in view here.

    Which one of these devices is:

    1) simpler?
    2) more efficient?
    3) lighter?

    scan_1595.jpg

    Whittle beats Goldberg, hands down.
     
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