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What was the best aircraft engine of the war?

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  • #16
    Rolls Royce Merlin
    Will no one tell me what she sings?--
    Perhaps the plaintive numbers flow
    For old, unhappy, far-off things,
    And battles long ago:
    -William Wordsworth, "The Solitary Reaper"

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    • #17
      The Napier Sabre




      Awesome bit of mechanical engineering

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      • #18
        It stands to reason that the best aircraft engine of the war is going to be a jet engine.....because it was a jet fighter that was the highest performing aircraft of World War 2.

        That aircraft was, of course, the Messerschmitt Me. 262 and was powered by the Junkers Jumo 004 in its early iterations.

        Designed by Dr. Anselm Franz, the Junkers Jumo 004 was the world’s first mass-produced, operational turbojet engine. It was also the first turbojet in the world with axial-flow compressors, afterburning, and a variable area exhaust nozzle. The original 004 A model flew for the first time in 1942, but it was not suitable for production because it was too heavy and used alloys in short supply in Germany.

        The 004 B production model was easier to manufacture, weighed less, and used air cooling for the combustor, turbine blades, and exhaust nozzle. The engine powered the Messerschmitt Me 262, the first operational jet fighter, and the Arado 234, the first operational jet bomber and reconnaissance airplane. Volume production of the 004 B began in early 1944. Junkers manufactured nearly 6,000 Jumo 004 engines by the end of World War II.
        [.....]
        https://airandspace.si.edu/collectio...urbojet-engine

        That aircraft also won the ACG 2015 tournament Most significant/influential fighter aircraft:

        https://forums.armchairgeneral.com/f...80#post4043080


        No other air breathing aircraft could approach the Me 262's 540 mph top speed in level flight.....well, only the Heinkel He162 powered by a BMW turbojet engine.
        Last edited by At ease; 20 Jul 18, 06:07.
        "It's like shooting rats in a barrel."
        "You'll be in a barrel if you don't watch out for the fighters!"

        "Talking about airplanes is a very pleasant mental disease."
        — Sergei(son of Igor) Sikorsky, 'AOPA Pilot' magazine February 2003.

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        • #19
          That the performance of any given aircraft is irrelevant here is made evident by a very simple reasoning.

          Consider the Do 335 Pfeil. It was faster than a Mustang.
          Does this mean its engine was better than the Mustang's? Heck no, because the Pfeil actually needed two of its engines to achieve that superior performance.

          The correct way of comparing the Mustang's engine and the Pfeil's engine is to look not at the performance of the two airplanes, but at the power/weight ratio of those two engines - meaning, you compare one Mustang engine with one Pfeil engine. What designers could then make by fitting one, two or four of those engines in an airframe is neither here nor there if we're only discussing the engines - very obviously.
          Michele

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          • #20
            Originally posted by T. A. Gardner View Post
            Well, what was the best aircraft engine of the war? Let's break it down some into radials, in-lines, and if you want to discuss it, jet engines.

            I would expect a lot of people to say the Merlin overall, but I'm nowhere close to convinced that's the case.
            Might help to settle upon how to define "best". Power to weight could be an obvious standard, but would variety of aircraft types using a particular engine and/or total numbers be another factor or classification?
            Breaking into three basic classes: radial, inline and jet also seems a realistic approach.
            TANSTAAFL = There Ain't No Such Thing As A Free Lunch

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            • #21
              Maybe use "Turbine" for "Jet"?

              Pruitt
              Pruitt, you are truly an expert! Kelt06

              Have you been struck by the jawbone of an ASS lately?

              by Khepesh "This is the logic of Pruitt"

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              • #22
                I think the Nakajima Sakae deserves a mention.
                Flag: USA / Location: West Coast

                Prayers.

                BoRG

                http://img204.imageshack.us/img204/8757/snap1ws8.jpg

                https://www.youtube.com/watch?v=5PtsX_Z3CMU

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                • #23
                  https://www.youtube.com/watch?v=sTD7DqXfRno

                  All about manifold pressure and what altitude the supercharger was optimized for

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                  • #24
                    Originally posted by Michele View Post
                    That the performance of any given aircraft is irrelevant here is made evident by a very simple reasoning.

                    Consider the Do 335 Pfeil. It was faster than a Mustang.
                    Does this mean its engine was better than the Mustang's? Heck no, because the Pfeil actually needed two of its engines to achieve that superior performance.

                    The correct way of comparing the Mustang's engine and the Pfeil's engine is to look not at the performance of the two airplanes, but at the power/weight ratio of those two engines - meaning, you compare one Mustang engine with one Pfeil engine. What designers could then make by fitting one, two or four of those engines in an airframe is neither here nor there if we're only discussing the engines - very obviously.
                    There are other factors involved than just power/weight(in a jet's case thrust/weight - it is accepted that it is not necessarily easy to compare energy outputs of piston and potentially comparable gas turbine engines).

                    An important factor is drag, which becomes increasingly more important the closer an aircraft approaches Mach 1.

                    Note that propeller tip speeds are approaching trans-sonic velocities(leading to rapidly diminishing efficiencies) even when an aircraft's airspeed approaches only 500(statute)mph, which is only .75Mach@35,000 feet.

                    https://www.engineeringtoolbox.com/m...ber-d_581.html

                    A prop's head on aspect represents the drag profile, whereas you will note that an axial-flow jet engine(we are talking Jumo 004 here) has a much smaller drag profile.

                    A 2 blade prop as used on the prototype Supermarine Spitfire K5054 of 1936 will obviously have less drag than say, a 5 blade prop on a Griffon engined Mk.XiV(14), or a six blade contraprop used on the last marks of Griffon powered Spitfire/Seafire/Seafang - naval development of the late war Spiteful.

                    To absorb ever increasing amounts of power on a piston engine, the area of "blade solidity" must necessarily increase, as it did with the above family line of aircraft.

                    Drag will increase with it.

                    It is the equivalent to a car.

                    Up the power output significantly and generally a stronger transmission is needed to absorb the increased power.

                    "There is no such thing as a free lunch".

                    An axial-flow turbojet can increase power output by increasing the number of compressor stages(increasing overall length), akin to raising the compression ratio on a piston engine, without necessarily increasing the diameter(or drag) of the compressor.

                    On the other hand a centrifugal-flow engine, such as used on the Gloster Meteor for example, must by necessity increase the diameter of it's double sided impeller compressor(therby increasing drag) to increase mass flow(air intake) unless RPM is increased.

                    Centrifugal-flow engines had significant limitations in this respect.

                    That is why their continued development for ever higher performing engines was not continued with much after the RR Nene(in production in 1946).

                    Another aspect to consider is that the high speeds you refer to being achieved by the P51(and other roughly comparable piston engined aircraft) were only obtained by going "through the gate", and accessing the extra power available by going to "War Emergency Power"(using GM1/Nitrous in the case of the Pfiel).

                    This is not a common engine power setting, and it was to be used for generally no more than 5 minutes at a time.

                    Any time an engine was operated in this manner, it was to be carefully checked for excess wear and if any aspect was of concern the engine was to be swapped out.

                    For piston engines this would take a number of men a number of hours and possibly more than a whole day using cumbersome overhead cranes.

                    Very large capacity engines such as the P&W R2800 on the P47 Thunderbolt or Wright R3350 on the B29(especially the B29 - known for quite poor engine reliability until after Gen. "Hap" Arnold fought, and won, the "Battle of Kansas") needed more man hours in this respect.

                    https://en.wikipedia.org/wiki/Battle_of_Kansas

                    Furthermore, for an engine to be able to be operated in "W.E.P." and develop more than normal output, it needed the help of very high octane fuels that were more problematic to formulate/refine/supply/store.

                    A revolutionary engine type such as the Jumo 004 was subject to a lesser extent to these problems.

                    It ran on kerosene, a very close relative to diesel and it could indeed run on diesel if that is what was available.

                    This type of fuel was much easier to organise(modern day equivalent AVTUR) when compared to AVGAS.

                    I would need to search a previous thread(no time right now) to copy the post where it was demonstrated with source reference that a Jumo 004 could be exchanged for another by one mechanic in 30 minutes using the purpose designed engine trolley.

                    I will find it later***.

                    From memory, it was from the book "American Raiders" by Col. Wolfgang Samuel USAF (rtd). dealing with "Watson's Wizzers".

                    Finally, the Jumo 004 was much cheaper to manufacture than a late war high output piston engine.

                    Again, from memory, it was about one third of it's equivalent in man hours/cost.

                    That fact is mentioned here:

                    https://forums.armchairgeneral.com/f...63#post5045763

                    @08.10 in the video I quoted in the above post where the presenter makes the cost/man hour comparison to the Jumo 213 engine powering a late war FW190D.

                    I have seen other sources corroborating such information.

                    Anyone familiar with the relative operation of piston engines as opposed to jets will understand the complexities involved in producing high power outputs from large capacity, highly tuned, highly boosted piston engines.

                    The Jumo 004, in comparison to the high output piston engine contemporaries, had a lot going for it - not just it's outright performance abilities.

                    EDIT*** Here is the reference about the time it takes to swap out a Jumo 004 - from six months ago:

                    https://forums.armchairgeneral.com/f...93#post4570293

                    That post also confirms, from the same Samuel's book source, the TBO of a US made General Electric J47 engine in the early 1950's as being only 25 hours.

                    I'm sure T.A.G. will be pleased to see that.

                    (I tried to add information as to a recent edit to the post - without it showing up once the edit was complete. - looks like another forum snafu)

                    (The reason for my edit was to provide more explanation about "blade solidity" as it applied to the Spitfire range of fighters)
                    Attached Files
                    Last edited by At ease; 22 Jul 18, 04:41.
                    "It's like shooting rats in a barrel."
                    "You'll be in a barrel if you don't watch out for the fighters!"

                    "Talking about airplanes is a very pleasant mental disease."
                    — Sergei(son of Igor) Sikorsky, 'AOPA Pilot' magazine February 2003.

                    Comment


                    • #25
                      Originally posted by Michele View Post
                      I don't think it's a good idea to start tossing around aircraft names. It's obvious that the performance of an aircraft can't depend solely on the engine.

                      So what I'd like to see, for starters, is the engines' power output, their weight, and therefore the power-to-weight ratio. The engine with the best power for its own weight sure is a strong contender for the first place, at least until one starts looking into reliability and other factors, such as the altitude where top power output could be reached.
                      The Mustang wasn't particularly fast where allied Aircraft are concerned.

                      The Rolls Royce Merlin went throughout the war keeping all the units it powered, at the pinnacle competitiveness.

                      The German jet engines accomplished what in WWII? Did it attain even temporary, local air superiority?
                      As for the Do 335, It was only fast with a squirt of MW50 boost. Without it was slower than the P51 and had a crap ceiling. And anyway, it would never have stood up to the Mk XIV Mk21 or next generation fighters, namely the MK 21 or Hornet. If the war was thought to drag on for another year, then perhaps the DH Vampire would have entered service earlier and dealt easily with any Jerry jet that phut-phutted about the sky.
                      ‘Tis said his form is tiny, yet
                      All human ills he can subdue,
                      Or with a bauble or medal
                      Can win mans heart for you;
                      And many a blessing know to stew
                      To make a megloamaniac bright;
                      Give honour to the dainty Corse,
                      The Pixie is a little shite.

                      Comment


                      • #26
                        Originally posted by G David Bock View Post

                        Might help to settle upon how to define "best". Power to weight could be an obvious standard,
                        I agree, and maybe I'll have to stop being lazy and dig up some actual figures.

                        but would variety of aircraft types using a particular engine and/or total numbers be another factor or classification?
                        I don't think so. Numbers produced may entirely boil down to "Well, the US industrial basis was immensely bigger and to boot it wasn't being bombed", and number of aircraft models equipped with a given engine might be ascribed to "It's the decent engine we could produce in numbers so we used that whenever we could".

                        Michele

                        Comment


                        • #27
                          Originally posted by Dibble201Bty View Post

                          The Mustang wasn't particularly fast where allied Aircraft are concerned.
                          With the exception of some very late war interceptors and prototypes it was fast, particularly the P-51H model, along with the F and G that weren't produced beyond two prototypes each. The H does about 460 mph at 15,000 and 485 at 25,000 feet. That's better than even the Griffon engine Spitfires and the Spiteful-- well at least during the war. The Spiteful manages to match that in the late 40's.

                          The Rolls Royce Merlin went throughout the war keeping all the units it powered, at the pinnacle competitiveness.
                          There were as many detail variants of the Merlin as the Allison or DB 600 series engines. It's these details that matter.

                          The German jet engines accomplished what in WWII? Did it attain even temporary, local air superiority?
                          As for the Do 335, It was only fast with a squirt of MW50 boost. Without it was slower than the P51 and had a crap ceiling. And anyway, it would never have stood up to the Mk XIV Mk21 or next generation fighters, namely the MK 21 or Hornet. If the war was thought to drag on for another year, then perhaps the DH Vampire would have entered service earlier and dealt easily with any Jerry jet that phut-phutted about the sky.
                          No, German jets accomplished nothing. This was due to several factors.

                          1. They were rushed into service and even experienced pilots weren't familiar with the quirks of jet flight. This, for example, compares to the USAAF experience where they had a fighter group of P-59 flying for nearly two years during the war learning how to operate jets. That training and experience made the transition much easier when it came. The RAF limited Meteor service in somewhat the same way giving easier flying jobs, like Diver patrols (shooting down V-1) to them to let the pilots gain experience with the plane. This meant that the Luftwaffe experienced a high accident rate with their jets and lost a good number of pilots due to nothing more than inexperience.

                          2. The German jets were crap in quality. The Me 262 experienced landing gear failures (nose gear) regularly. The He 162 came unglued in flight on a regular basis. The original Ar 234 was landing on skids! The 262 and 234 also had serious issues with getting the controls balanced properly. All of them suffered from poor brakes and weak hydraulics.

                          3. Lack of fuel. It doesn't matter that they ran on lower grade, easier to produce fuels when they were taking 3 to 5 times the fuel for a sortie that a piston engine equivalent would need. The Germans simply couldn't produce the fuel necessary to put them in the air in big numbers.

                          The Do 335 was fast, and not because of MW 50 boosting. In fact, most models didn't have it fitted. The one that mostly was going to use it was the A-6 nightfighter model optimized for altitudes of 15,000 to 20,000 feet. Why that range? That's where RAF bombers fly for the most part. The 335 is slower than a P-51H but is also faster than a P-51D. The Do 335 certainly would have been competitive with late war Allied fighters in speed.

                          As for the never-builts, or post war prop planes, sure, Britain continued to use them into the 50's. The US pretty much got rid of prop fighters by the end of the 40's. The never-builts like the P-72 would have been the pinnacle of speed for a prop fighter. The P-72 could have hit about 520 mph in the production models. The XP-47J did hit 504 and was the prototype for the prototype XP-72. The P-82 could hit 480+ and could fly from London to Moscow and back after loitering 30 minutes over Moscow.
                          In jets, the US was pushing forward on a number of them in addition to the P-80. There was the P-84 Thunderjet, the P-86 "Jet Mustang" (not the version that became the Saber but rather the version that became the FJ Fury), the FH Phantom (first jet to land and take off a carrier), etc.

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                          • #28
                            To put it in another way, my argument that you don't judge an engine on the basis of the performance of the aircraft it is mounted on will go on as follows.

                            I won't name actual WWII fighter names, so that nobody gets stuck on pointless details. I'll make an entirely hypothetical example.

                            Fighter model A uses engine X. With that engine, it achieves our reference top speed (we'll call it 100%).
                            Now that's actually model A1. Then up comes model A2, with the same engine, but it achieves a speed of 95% (in comparison to the previous model). Why is that? Because designers crammed heavier guns, more ammo, more armor and more fuel in the airframe. A2 is heavier, and therefore slower - even if the engine is the same and the engine power output is the same.
                            Maybe the users then add a tank-opener gun pod to the belly of A2, that becomes A2-a, and the added air drag (and weight) reduce top speed to 90%.
                            Yet the engine and its power are still the same.

                            Now, those who insist on judging an engine by the performance of the aircraft it's fitted on might say, let's look at the aircraft with the best performance, let's look at model A only. But naturally they then proceed to judge engine X - mounted on aircraft A - in comparison with engine Y - mounted on aircraft B.
                            No guys. If you can show an aircraft A with the engine X installed going faster than the same aircraft A with the engine Y installed, then yes, you will have proven that engine X is better than engine Y. Otherwise, no.

                            That isn't even without going into the idea of judging engines by comparing an aircraft that is propelled by one engine with an aircraft that is propelled by two.


                            Michele

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                            • #29
                              Johnny Johnson said that the Mustang gave its pilot an even chance fighting Nazis at high and low altitude and could dive with the Nazis, something the Spitfire apparently couldn't do. He said that far too many Spitfire pilots were last seen doing a half roll and diving after a fleeing Nazi.

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                              • #30
                                I wasn't going to answer someone who sees four different aircraft as the same, but I suppose i'd better....

                                Of the P51H, I have seen no actual data that pins its 487 mph.tag apart from in the prototype version. In the production, I have seen speeds of between 451 and 474 mph, and even the data that is available is flawed, misleading or contradictory, That the F82 could just about do over 460mph. But then the Spiteful MK XIV went 484 mph and climbed at 4,890 ft per minute, A Spiteful Mk XVI went faster, at 494mph and like all Griffon engined fighters, had no peers at high altitude. The thunderbolt 505mph is just as valid as the reports from some Spitfire XIV pilots in combat saying that they were doing 500mph.

                                As can be seen in this argument anyway, was that the prop driven fighter was on its way out as nothing could be achieved more at the 500mph+mark, even the Spiteful was really just a test-bed for the Supermarine Attacker Jet. and like the Spiteful, the P51H saw no combat and the reliability of US tests of the day are rather suspect, especially if we go by the Navy and the Patuxent testing with the example of the performance data for the F4U-4 Corsair.as pointed out to a poster some years ago.

                                eddie3rar: Johnny Johnson said that the Mustang gave its pilot an even chance fighting Nazis at high and low altitude and could dive with the Nazis, something the Spitfire apparently couldn't do. He said that far too many Spitfire pilots were last seen doing a half roll and diving after a fleeing Nazi.
                                Johnny Johnson said many things in his book and interviews. He also said that the Spitfire was the best fighter of the war. It is also disingenuous not to quote him in full and in what context he made those remarks.

                                The Rolls-Royce Merlin and Griffon were the best Aero piston engines of the war..The Merlin improved the performance of two of the USAAF's front-line fighters.
                                Last edited by Dibble201Bty; 25 Jul 18, 04:30.
                                ‘Tis said his form is tiny, yet
                                All human ills he can subdue,
                                Or with a bauble or medal
                                Can win mans heart for you;
                                And many a blessing know to stew
                                To make a megloamaniac bright;
                                Give honour to the dainty Corse,
                                The Pixie is a little shite.

                                Comment

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