Rear Bear Vs. The Russian Bear

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by pie_row, Dec 2, 2009.

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  1. Jan 30, 2010 #461

    pie_row

    pie_row

    pie_row

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    I looked for the auction that sold TAG Porsche engines didn't find it. (It is listed in a prior page on this thread.) They were selling used engines that had won 4 and 5 races. Modern F1 engines are required to be used for 2 races. Porsche entered into the F1 turbo engine building business from an endurance racing background. They built 50 hr engines at 950 hp from 1.5L. They weren't built to cool that much power continuously but mechanically they made that much power for 50hrs before needing to be rebuilt. At a power density of 666hp/L it should be possible to make a 50hr TBO engine that is aircraft rated. That would be uprating the Tag Porsche for continuous output. It may be possible to build a 50hr air race engine that is rated at 1,000hp/L. That is my design point. Keeping the average piston speed down is critical for long engine life. That means a short stroke. Cooling and knock dictates a small bore. Getting enough bearing area into a small enough package dictates a two crankshaft arrangement. So the layout that I'm looking at is a twin V-16 42.5mm bore and 33mm stroke. At the average piston speed that NASCAR and F1 use it would make insane amounts of power. 2,100 hp for the twin engine combo. 1,400hp/L back it off to 1,400hp for both crankshafts together and should last a lot longer than at 2,100hp.



    This calc shows the engine The calc has two self compensating math errors I haven't gone back and fixed them yet. But it does work.​
    As far as the money goes ya it wouldn't be cheap but it would be fun and I mean fun.​
     
  2. Jan 30, 2010 #462

    autoreply

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    Well, lubrication, bearing heating, vibrations wear and mechanical wear also rises a bit more than linearly with rising RPM's...
     
  3. Jan 31, 2010 #463

    pie_row

    pie_row

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    Very true,

    You need to reduce the bearing diameter to keep the rubbing velocity down. Mechanical wear is a function of the rubbing velocity as well as the pressure applied. So smaller pistons help with that....
     
  4. Feb 2, 2010 #464

    macdonca

    macdonca

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    I can show you auctions where complete R-3350's are selling for 5k. A running 3350 + homebuilt air racer is still going to cost 2-5 mils + upkeep.

    An F1 race is only a little over an hour long.

    Doubt it. The Pond Racers motors were seriously de-tuned and they still came apart. Remember, if it was that easy somebody would have done it already.


    I am an engineer by trade. Just because math calculations work on paper, does not mean they are practical or will work in "real life"
    I can think of a lot more fun ways to burn 5 million dollars. Why dont you just buy a T-6 and go racing? You can probably get the plane and all the required flight training for under 150k. Save yourself a couple of million and 10 to 20 years of frustration.
     
  5. Feb 2, 2010 #465

    macdonca

    macdonca

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    Is your 1-off PSRU that your going to have to machine yourself going to be as reliable as the motor?
     
  6. Feb 2, 2010 #466

    macdonca

    macdonca

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    And this is why your math does't work.

    Your engine requires 14.5 grams of fuel per rev accourding to your model.

    at 10k rpms thats 145,000 grams of fuel per minute

    8,700,000 grams of fuel per hour. or 19180.2 lbs per hour

    at 6 lbs per gal thats over 3,000 gal of fuel for an hour of consistant 10k RPM operation. Sounds thirsty.

    All of your power to wieght quotes are flawed because they dont dont take into effect the PSRU, Radiator and Cooling equipment, and all that extra fuel you have to carry. At the end of the day, you are worse off than the tried and true equipment thats already in use.
     
  7. Feb 3, 2010 #467

    macdonca

    macdonca

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    ok we'll call it 120 gal/hr. And we'll assume your using 60 gal on board.

    so were at 360 lbs in fuel

    WHAT?

    25 gals of water or 200 lbs total liquid on board 85 gallons.

    Where are you going to fit 85 gallons in a homebuilt the size of an AR-5? Regardless, the weight of your fuel and water (your figures) weigh more than the entire AR-5 did. All this weight pulled by a belt and pulley PSRU?
     
  8. Feb 3, 2010 #468

    JimCovington

    JimCovington

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    I'm pretty sure we've jumped the shark...err, I mean changed topic...once again, so the plane with the 1400hp engine is NOT the size of the AR-5.

    And of course the belt+pulley arrangement will hold up to the stress - didya see the size of that lathe frame? :roll:
     
  9. Feb 3, 2010 #469

    macdonca

    macdonca

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    Yeah... Time to put this thread to bed. Its more comical then technical.
     
  10. Feb 8, 2010 #470

    MadRocketScientist

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    Hence the reason its still alive, gotta have something for light reading;);)
     

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