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Thread: ROLLS-ROYCE CRECY

  1. #11
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    Default Re: ROLLS-ROYCE CRECY

    5000hp / 12 cylinders = 416.666 hp per cyl.... Wow!

    Considering that for an equal rpm the 2-stroker has twice as many power strokes most likely has something to do with it. Horsepower = torque x rpm. I'd like to find out what the max RPM of the Crecy was...

    I haven't heard of the 2-cycle vs 4-cycle displacement problem, but it does state the 5000 hp horsepower rating at the RR engine website Peashooter posted:

    Crecy – V12, 90°, sleeve-valve, liquid cooled, 26.1 litre, supercharged, two-stroke, mechanical fuel injection (from Focke Wolf 190) Otto-engine. The 1942 prototype had surprisingly low fuel consumption at the highest power output. In December of 1945, after eight years of development, work on the Crecy was terminated. At that time the Crecy was capable of double the horsepower of conventional 4-stroke designs of the same displacement. Only six Crecy engines were built, all with even serial numbers (2, 4, 6, 8, 10 and 12). This has led to confusion as to the numbers made. Crecy engine #10, achieved the highest test horsepower in December 1944, putting out the equivalent of 5,000 brake horsepower.

  2. #12
    Type327unreg Guest

    Default Re: ROLLS-ROYCE CRECY

    Quote Originally Posted by matt
    i've heard that once a two stroke reaches a certain size in cu. in.'s it's ability to prduce more power than a four stroke dies, is this true?

    if so, how did the crecy produce 5000 hp?
    Clearly you've been speaking to four-stroke bigots Most, if not all, of the really big engines out there are two-stroke. I'm talking here of engines with displacements up into the thousands and even tens of thousands of cubic inches per cylinder. No, those aren't typos, tens of thousands, per cylinder. These units don't actually produce a lot of power for their size (it's hard to make a lot of power when your redline is at maybe 200 rpm), but that's not what they're built for, they're built for torque. Torque up in the millions of lb/ft for the really big ones. Two-strokes of this size are pretty much uniformly diesel units, and I believe in the early design stages the Crecy was going to be a diesel, I may be thinking of another experimental Rolls Royce from the period though. With two-strokes dominating in the arena of small engines too, it's really just the bit in the middle where four-strokes are, for now, allowed to pretend they're king

    Type327, posting unregistered because I changed my email address and forgot my password, I'm so organised

  3. #13
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    Default Re: ROLLS-ROYCE CRECY

    Quote Originally Posted by Type327unreg

    Type327, posting unregistered because I changed my email address and forgot my password, I'm so organised
    Three Two Seven... click on the contact us link on the bottom, send me an email with your username or reasonable facsimile, and or, your old email address, as well as, your new email addy and I'll get the board software to send you a reset notice. May have to wait till late tomorrow or the next day, as I'm gonna be in the air for a few hours comin up here tomorrow..

    Wayne

  4. #14
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    Default Re: ROLLS-ROYCE CRECY

    I'm talking here of engines with displacements up into the thousands and even tens of thousands of cubic inches per cylinder. No, those aren't typos, tens of thousands, per cylinder.
    You mean like this house-size monster? (2-story house, that is...)

    http://www.bath.ac.uk/~ccsshb/12cyl/ <--click here to see it!

    -----------------------------------------------------------------

    The Most Powerful Diesel Engine in the World!

    "The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine is the most powerful and most efficient prime-mover in the world today. "

    "The cylinder bore is just under 38" and the stroke is just over 98". Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower."

    "14 cylinder version:
    Total engine weight: 2300 tons (The crankshaft alone weighs 300 tons.)
    Length: 89 feet
    Height: 44 feet
    Maximum power: 108,920 hp at 102 rpm
    Maximum torque: 5,608,312 lb/ft at 102rpm

    "

  5. #15
    Type327unreg Guest

    Default Re: ROLLS-ROYCE CRECY

    Quote Originally Posted by AAFO_WSagar
    Three Two Seven... click on the contact us link on the bottom, send me an email with your username or reasonable facsimile, and or, your old email address, as well as, your new email addy and I'll get the board software to send you a reset notice. May have to wait till late tomorrow or the next day, as I'm gonna be in the air for a few hours comin up here tomorrow..

    Wayne
    Cheers Wayne email sent.

    Eddie

  6. #16
    Unregistered Guest

    Default Re: ROLLS-ROYCE CRECY

    None of this is true, marine diesels put out around 80-100 bhp per 1000 rmp and litre displacement, i.e. about 5 times a turbocharged formula one car :-) .. thus big two strokes are the worlds highest performing engines.

    B.t.w. the Crecy was to some extent built to compete against the turbojet's since rollsroyce didn't have control of the patent, however they managed to screw Whittle over so he didn't get nothing for his contributions .. thus the crecy died.

    But if you look at the power to wheight, it can match most of the modern bypass engines and certainly has better fuel economy !

    Quote Originally Posted by matt
    i've heard that once a two stroke reaches a certain size in cu. in.'s it's ability to prduce more power than a four stroke dies, is this true?

    if so, how did the crecy produce 5000 hp?

  7. #17
    Unregistered Guest

    Default Re: Big two strokes

    Quote Originally Posted by AirDOGGe
    You mean like this house-size monster? (2-story house, that is...)

    http://www.bath.ac.uk/~ccsshb/12cyl/ <--click here to see it!

    -----------------------------------------------------------------

    The Most Powerful Diesel Engine in the World!

    "The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine is the most powerful and most efficient prime-mover in the world today. "

    "The cylinder bore is just under 38" and the stroke is just over 98". Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower."

    "14 cylinder version:
    Total engine weight: 2300 tons (The crankshaft alone weighs 300 tons.)
    Length: 89 feet
    Height: 44 feet
    Maximum power: 108,920 hp at 102 rpm
    Maximum torque: 5,608,312 lb/ft at 102rpm

    "
    That's a BMEP of 544 psi!!!!!!

    Welcome to the wonderful world of two strokes. Four strokes are doomed... <LOL>

    Truth is, the 4S has one (and ONLY one) advantage over the direct injected 2S: operating range. In every other respect the 2S wins out. SFC, power density, power to weight, TBO, etc. Name it, except for wide operating range and widely varying load conditions, and the 2S beats the 4S every time. 2S engines got their bad rep from carburation and poor fuel-air management. In the real world of engines that have to make money for their manufacturers, 2S are equal or superior to their 4S brethren and mostly win out.

    I myself was a 4S snob until about two years ago. I had studied enough and done enough engine development that when a person I repsected said "why NOT a 2S?", I set out to show him and came up with an answer that I didn't expect. Knowing the thermodynamics of tubine engines as well, I didn't expect the next answer.

    The most efficient engine on the face of the earth is a "combined cycle" using a Brayton compression and expansion cycle on either side of an Otto cycle 2S piston engine. Whether compounded (Brayton cycle coupled to the power shaft) or free (Brayton cycle un-coupled), the efficiency and power density blows every other option to bits.

    The issue that keeps 2S engines in the background of 4S is simple. We need engines with wide operating ranges for most uses in our everyday life. Cars, trucks, motorcycles, boats, etc. all need engines that function well under a 10:1 or greater idle to max power range. Our average car produces ~5 HP in stop and go traffic at an SFC of <.45 and still manages 200 HP at under .50! No 2S can do this.

    Take that idle-to-max HP requirement to less than 5:1 and the 2S shines. Over a narrow operating range, the combined cycle 2S can achieve 50% or more improvement over the 4S in SFC and power density.

    So who uses narrow operating range engines? Aircraft.

    Because props on any aircraft function at a very narrow range of RPM and the power levels from take off to cruise do not vary more than 2:1, aircraft are an excellent cnadidate for highly efficient, high power density, narro operating range 2S technology. The average GA aircraft sees 2700 to 2300 RPM from takeoff to climb to cruise to descent. That's only a 16% variance in RPM and a 50% variance in power. Less than one fourth that of the worst car engine.

    In load range, the aircraft engine uses 75 to 100% of the air available at any time (for a given altitude) unless we are descending. The car engine uses as little as 10%, but still must be able to operate efficiently at 100%.

    Clearly, the aircraft (and air racing ) world screams for a 2S engine. The problem is that no one else does and aircraft are a small market. Hopefully, the market has and will continue to expand enough to make development of a superior 2S engine viable.

    Eric Ahlstrom

  8. #18
    Join Date
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    Default Re: Big two strokes

    Quote Originally Posted by Unregistered
    In load range, the aircraft engine uses 75 to 100% of the air available at any time (for a given altitude) unless we are descending. The car engine uses as little as 10%, but still must be able to operate efficiently at 100%.

    Clearly, the aircraft (and air racing ) world screams for a 2S engine. The problem is that no one else does and aircraft are a small market. Hopefully, the market has and will continue to expand enough to make development of a superior 2S engine viable. Eric Ahlstrom
    Perhas the introduction of a "Superbore" class can enable such development. The IO-12 is a great start and OEMs like Lycoming and Thielert are at Reno to develop, then deploy new technologies! (At least new to Gen-Av.) To that end, I hope that the rule makers don't stifle development.
    Rutan Long EZ, N-LONG
    World Speed Record Holder

  9. #19

    Default Re: ROLLS-ROYCE CRECY

    HEY PISTON HEAT

    look at all those big prime movers..... marine and stationaey...... with gaggles of oil injection tubes w/underside honeycombs to cold soak all that piston heat away...... on other away i guess

    BMarsh

  10. #20

    Default Re: ROLLS-ROYCE CRECY

    SUGGESTION TO MODERATOR


    Move this to the regular board for more action


    this thread is "lost in space" at the bottom of the web site menu!!!!

    BMarsh

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