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Radial Engine Destruction...What Caused This?

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  • Radial Engine Destruction...What Caused This?

    I came back from an auction last Saturday night with two cylinder / head assemblies from Pratt & Whitney R2800 radial engines. Both of the assemblies have major damage, but this one intrigues me. I know that something of this nature can happen if the prop is not pulled through enough to get the oil out of the lower cylinders, but what else may have caused this?

    In the first pic you can see the whole assembly, with the chunk ripped out of the cylinder:



    And this pic shows in a bit more detail the broken cylinder:



    And this third pic shows the chunk that was ripped out of the cylinder, plus some of the stripped / bent / snapped studs that hold the cylinder onto the crank case.



    In doing a bit of research I found that the P&W R2800 was an eighteen cylinder, double row engine that was used on many different aircraft during its production run (1939 - 1960) including the Hellcat, Corsair, and B-26 Marauder during the 2nd World War.

    I also found this link to a video of a cutaway engine in motion.

    http://andersonaeromotive.net/pratt-...-wasp-cutaway/

    So...other than too much oil left in the lower cylinders upon start-up, what else could have caused this cylinder to blow out of the crank case?

  • #2
    bent studs?

    Think collision.

    Gear up landing perhaps?

    A tug backed ito the parked aircraft while it sat on some lonely ramp in the middle of nowhere??

    Comment


    • #3
      what's the inside of the head look like?

      tell you the truth that's one thin flange to mount a cylinder on, no matter how many bolts...

      cast iron can be brittle as all hell, if a cylinder was running too lean and an exhaust valve dropped on one side of the head I could see it "popping the top off of the popper" so to speak...

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      • #4
        Improper torque of the cylinder bolts is one way to shuck an aircraft cylinder. The torque procedure is specialized and must be followed religiously.
        Looks like the rest of the cylinder, i.e. the aluminum upper component is not damaged.
        The bottom is probably not cast iron but more likely hi strength steel. That is how the standard recip engines are built. The cylinder head is aluminum and is screwed on and tightened with a 4 ft wrench immediately after the head comes out of the oven. It is a shrink fit. Amazing (to me anyway) to watch.

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        • #5
          I know its an outsider but sucking in water destroyed a local farmers land rover, cylynder looked like it was blown out the side
          Mark

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          • #6
            What could cause this? From below, "...during the 2nd World War". How about enemy machine gun fire?

            I am genuinely curious, just why did you buy them? Some kind of collection? Scrap metal?



            Originally posted by john hobdeclipe View Post
            I came back from an auction last Saturday night with two cylinder / head assemblies from Pratt & Whitney R2800 radial engines. Both of the assemblies have major damage, but this one intrigues me. I know that something of this nature can happen if the prop is not pulled through enough to get the oil out of the lower cylinders, but what else may have caused this?

            In the first pic you can see the whole assembly, with the chunk ripped out of the cylinder:



            And this pic shows in a bit more detail the broken cylinder:



            And this third pic shows the chunk that was ripped out of the cylinder, plus some of the stripped / bent / snapped studs that hold the cylinder onto the crank case.



            In doing a bit of research I found that the P&W R2800 was an eighteen cylinder, double row engine that was used on many different aircraft during its production run (1939 - 1960) including the Hellcat, Corsair, and B-26 Marauder during the 2nd World War.

            I also found this link to a video of a cutaway engine in motion.

            http://andersonaeromotive.net/pratt-...-wasp-cutaway/

            So...other than too much oil left in the lower cylinders upon start-up, what else could have caused this cylinder to blow out of the crank case?
            Paul A.

            Make it fit.
            You can't win and there is a penalty for trying!

            Comment


            • #7
              does the top of the piston get below the damaged area? in that case it might be water, although you usually bend a rod.

              Comment


              • #8
                Apparently, this sort of thing can just "happen". The flying club I was in while in the Navy had a T-34 with a horizontally opposed engine. One of the guys was taxiing out for a takeoff when the engine began ticking. He shut it down and had it towed back to the hangar. Subsequent inspection revealed a developing condition similar to that reported in the OP.
                Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                ~Practitioner of the Electromechanical Arts~

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                • #9
                  The engine is also known as the 'double wasp'. I am curious why you bought them. Or rather, carried them home.

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                  • #10
                    Originally posted by koda2 View Post
                    The bottom is probably not cast iron but more likely hi strength steel.
                    Iv never seen steel break like that unless it was hit with liquid nitrogen first...

                    and just something about the way it's rusting looks cast to me too. could be wrong though...


                    To the OP, Did you know the cylinders position on the block? was it a lower one?

                    the engines were dry sump but if they sat they could bleed oil down into the lowest cylinder past the rings and when someone went to fire it up it could hydrostatic lock,,, ?

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                    • #11
                      One of those engines is at the Antique Airfield Museum outside of Blakesburg, Iowa in cut away condition. Very complicated machine. What caused the damage, I can't say for sure. Metal fatigue? The cylinders are on the engine body in offset position from the next one and the engine is about three or four feet long not in line as most radial engines like the Stearman engines. The engine used in the Japanese Zero had two banks of cylinders, one bank behind and offset for air flow cooling. The PW R2800 cylinders were set in a spiral configuration. Not sure how a gear up landing would get a cylinder. But Stranger things happen.
                      Extent of my knowledge on this.
                      Krutch


                      Mentally confused and prone to wandering!

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                      • #12
                        Originally posted by A.K. Boomer View Post
                        the engines were dry sump but if they sat they could bleed oil down into the lowest cylinder past the rings and when someone went to fire it up it could hydrostatic lock,,, ?
                        Standard radial engine start up includes pulling the engine through two complete revolutions by hand to check for hydrostatic lock. Not the most fun thing in the world.

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                        • #13
                          Just a wag, (wild ass guess) but I think that someone didn't follow the correct torque sequence. They may have gone back & re-tightened those bolts at a later date if they were in an easy spot to get to.

                          John

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                          • #14
                            From looking at the few bolts/studs that are there, my guess is all the bolts/studs but the five holding that part of the flange down, either broke or loosened or both and that caused that part of the flange to break off. The picture of the bolts/studs is not real clear but it appears the cylinder had been moving on the bolts/studs for some time before the final failure. Now on an engine like that, "some time" could have been just a few minutes depending on RPM's and load.

                            Comment


                            • #15
                              Several interesting facts here, in a quick analysis.
                              The fact that the studs broke ( as seen) means the fasteners exceeded their tensile strength
                              That means the jug was being pulled off the crankcase in some way.
                              Fact, the sleeve ( CI ?) shows fractures that mimic the fasteners location says ( to me ) that the sleeve was under tensile strain as well and failed , but held nearer the fasteners ( note the crowns , or castle like failure lines showing the major stress points.
                              The fact that the brerak is clean , with no bending /warping of the flange ends means Cast Iron, as steel would have bent ends near the break.

                              Rich

                              My thoughts are hydro lock as pointed out earlier, or a rod going through the crankcase, adjacent to the jugs

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