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  • #61
    Re: Lap Speeds

    Originally posted by toldjaso View Post
    Iffin you say so.
    Looks like he could fly a lot faster if he didn't need 2000+ gallons of ADI and spray bar water to finish a 6 lapper.
    Is it home yet, or hiding in a hanger at Stead?
    Saw on FB that it was back home. Can't find the post now though.

    Comment


    • #62
      Re: Lap Speeds

      Nobody mentioned that running ADI flow rates tuned for max horsepower in low power settings can cause the mist to come out of suspension, pool, and hydrolock a cylinder.

      When I say "hydrolock" I don't mean a cylinder full enough to snap the rods but rather a combustion chamber just full enough such that it causes huge forces at top dead center.

      Just a possibility.

      I've replaced two hydrolocked engines this week and one only broke the top ring land while the other one folded over the rod.

      Comment


      • #63
        Re: Lap Speeds

        First my hat is off to Tiger and Stevo…fantastic job by all the unlimited guys, and especially to those two. Best race I’d ever seen…tactics played by both of these great race pilots were spot on

        A lot of conjecture by arm chair racers as to whether or not Tiger left an ADI switch ON for landing… in Tiger defense it doesn’t make difference. The switch only turns ON the ADI pump. It doesn’t regulate the flow of ADI, the ADI regulator does. The regulator will start flowing at about 40” and on the TUBE engine flows 3-3.5 GPM at full throttle.
        If this was an issue as some are saying, hell you wouldn’t even be able to take off. You arm (turn the ADI on) prior to take off...actually during the run up. I turn it off after the race as it tends to bring the induction temp back up and can clean the plugs up… though if its busy with Maydays going on all around, I’ll leave it ON just in case you need to do an emergency Go Around. SO…, I guess its Tigers option as to what switch he elects to put in what position and has nothing to do with water being found in the oil. For general information there no way for the ADI to flow naturally into the oil system nor to flow UP the induction tube... it would drain out of the supercharger drain onto the ramp.

        The water out of the cylinder/exhaust pipe would be indicative of a cracked head. The valve seats are screwed into the heads on a Merlin… not pressed into bronze inserts as some suggested. The combustion chamber on those particular RR 700 series transport heads has been prone to cracks and needs TLC ….some seats replaced and areas weld after every race…I know as I’d been doing the weld repairs and seat inserts up until 2013.

        Water in the oil could be caused by an internal leak in the oil heat exchanger/radiator or by a head cracked through into the water jacket and on into the valve train area. The combustion pressure may have pressurized the cooling system, venting coolant past the coolant relief valve and overboard… thus producing the vapor trail you saw on the last lap. Cracked piston/liner would have made a mess of things… lots of oil down the side, but it would have had to crake the liner to get coolant into the oil.

        As far as all the spray bar water… in the picture…. that is usually an indicator of the engine running too cool and not converting the spray bar water to steam…could be just the dew point/humidity in the air condensing the steam to vapor or, could be that Tiger knew he had a problem…oil temp going up…. coolant going up and just opened the bypass valve too nurse the old Witch past the kid…….

        Anyway it was one hell of a race….hope this helps clarify a few things

        Comment


        • #64
          Re: Lap Speeds

          Originally posted by IcePaq View Post
          Nobody mentioned that running ADI flow rates tuned for max horsepower in low power settings can cause the mist to come out of suspension, pool, and hydrolock a cylinder.

          When I say "hydrolock" I don't mean a cylinder full enough to snap the rods but rather a combustion chamber just full enough such that it causes huge forces at top dead center.

          Just a possibility.

          I've replaced two hydrolocked engines this week and one only broke the top ring land while the other one folded over the rod.
          Cooorect.
          Another thing that some people like to ponder is that there is only just so much room in that combustion chamber to jam all of that air, racing fuel, ADI fluid, and in the good old days some people runnned that there nitrous, too. When that piston comes up to squeeze it all down good and tight, you just might have more in there than it really wanted to swallow.

          A year or so ago, I remember a post on here where someone with the 'knowin wrote up a great post about what all goes on in a Merlin at race power. So many what-evers per second, etc. It was really unbelievable.
          Anybody got that to re-post it??

          Comment


          • #65
            Re: Lap Speeds

            Originally posted by bruce lockwood View Post
            First my hat is off to Tiger and Stevo…fantastic job by all the unlimited guys, and especially to those two. Best race I’d ever seen…tactics played by both of these great race pilots were spot on.....
            Bruce, thank you so much for dropping by..!
            Wayne Sagar
            "Pusher of Electrons"

            Comment


            • #66
              Re: Lap Speeds

              I just looked my old VHS cassette from 1998 Reno races...

              Bruce, also thank you so much for this detailed explanation from an expert's view!

              Only one more question:
              Is it possible that some dives on the race course (even only slight) with full throttle cause RPMs to much spinning up or is this no problem because it happens only short time?

              Did race engines have a mechanical or electronical RPM limiter/regulator as known as example from high revvin' car or bike engines?

              thx
              Gibbs
              Last edited by Gibbs; 09-20-2014, 05:07 AM.

              Comment


              • #67
                Re: Lap Speeds

                PHP Code:
                Is it possible that some dives on the race course (even only slightwith full throttle cause RPMs to much spinning up or is this no problem because it happens only short time

                You are forgetting the prop is constant speed aren't you? RPM is set and it stays there.

                GP

                Comment


                • #68
                  Re: Lap Speeds

                  Originally posted by toldjaso View Post
                  Cooorect.
                  Another thing that some people like to ponder is that there is only just so much room in that combustion chamber to jam all of that air, racing fuel, ADI fluid, and in the good old days some people runnned that there nitrous, too. When that piston comes up to squeeze it all down good and tight, you just might have more in there than it really wanted to swallow.

                  A year or so ago, I remember a post on here where someone with the 'knowin wrote up a great post about what all goes on in a Merlin at race power. So many what-evers per second, etc. It was really unbelievable.
                  Anybody got that to re-post it??
                  If you could slow time down, and examine just one second of what takes place inside a filly operating Merlin engine at full power, what would you find?

                  In that one second, the V-12 Rolls-Royce Merlin engine would have gone through 60 revolutions, with each of the 48 valves slamming open and closed 30 times. The twenty four spark plugs have fired 720 times. Each piston has traveled a total of 60 feet in linear distance at an average speed of 41 miles per hour, with the direction of movement reversing 180 degrees after every 6 inches. Three hundred and sixty power pulses have been transmitted to the crankshaft, making 360 sonic booms as the exhaust gas is expelled from the cylinder with a velocity exceeding the speed of sound. The water pump impeller has spun 90 revolutions, sending 4 gallons of coolant surging through the engine and radiators. The oil pumps have forced 47 fluid ounces, roughly one-third gallon, of oil through the engine, oil cooler, and oil tank, scavenging heat and lubricating the flailing machinery. The supercharger rotor has completed 348 revolutions, it's rim spinning at Mach 1, forcing 4.2 pounds or 55 cubic feet of ambient air into the combustion chambers under 3 atmospheres of boost pressure. Around 9 fluid ounces of high octane aviation fuel, 7843 BTU's worth of energy, has been injected into the carburetor along with 5.3 fluid ounces of methanol/water anti-detonant injection fluid. Perhaps 1/8 fluid ounce of engine oil has been either combusted or blown overboard via the crankcase breather tube. Over 1.65 million foot pounds of work have been done, the equivalent of lifting a station wagon to the top of the Statue of Liberty.

                  In that one second, the hard-running Merlin has turned the propeller through 25 complete revolutions, with each of the blade tips having arced through a distance of 884 feet at a rotational velocity of 0.8 Mach. Fifteen fluid ounces of spray bar water has been atomized and spread across the face of the radiator to accelerate the transfer of waste heat from the cooling system to the atmosphere.

                  In that one second, the aircraft itself has traveled 704 feet, close to 1/8 mile. The pilot's heart has taken 1.5 beats, pumping 5.4 fluid ounces of blood through his body at a peak pressure of 4.7 inches of mercury over ambient pressure. Our pilot happened to inspire during our measured second, inhaling approximately 30 cubic inches (0.5 liter) of oxygen from the on-board system, and 2.4 million, yes million, new red blood cells have been formed in the pilot's bone marrow.

                  In just one second, an amazing sequence of events have taken place. Don't blink!
                  Sky Critter

                  Comment


                  • #69
                    Re: Lap Speeds

                    You did not give credit for that quote, Critter. You didn't even put it in quotes to indicate it is not yours.

                    Somebody put a bunch of work into that piece of writing. Tom should get some credit for that work!

                    Neal

                    Comment


                    • #70
                      Re: Lap Speeds

                      Here's a link to Tom Fey's full article (scroll down): http://www.enginehistory.org/rolls-royce.shtml

                      Here's a link to the companion piece by Tom Fey, One Second on the Course With Dreadnought (scroll again): http://www.enginehistory.org/TM/htm/tmv5n4.shtml

                      Comment


                      • #71
                        Re: Lap Speeds

                        Originally posted by wingman View Post
                        You did not give credit for that quote, Critter. You didn't even put it in quotes to indicate it is not yours.

                        Somebody put a bunch of work into that piece of writing. Tom should get some credit for that work!

                        Neal
                        This piece is all over the web and where I found it didn't list any credits. Just trying to help. I guess I could have been an ass and just said "do a search of the AAFO threads and you'll find it" but, I figured I'd just make it easy. If I were brilliant enough to come up with that article, I certainly would have let everyone know it was mine...
                        Sky Critter

                        Comment


                        • #72
                          Re: Lap Speeds

                          Originally posted by Sky Critter View Post
                          This piece is all over the web and where I found it didn't list any credits. Just trying to help. I guess I could have been an ass and just said "do a search of the AAFO threads and you'll find it" but, I figured I'd just make it easy. If I were brilliant enough to come up with that article, I certainly would have let everyone know it was mine...


                          Thank You to all of you people who replied in one way or another to my request to re-post this article.
                          I am glad that whoever gave credit to who wrote it got the credit to who deserves it.
                          Now let's also remember, if you put it on the web, anybody can copy it and re-post it. You no longer own it. That being said, again, thanks, guys.
                          Now let's enjoy this great piece of trivia together! Really remarkable, I think, as I read through it.

                          Comment


                          • #73
                            Re: Lap Speeds

                            Originally posted by IcePaq View Post
                            Nobody mentioned that running ADI flow rates tuned for max horsepower in low power settings can cause the mist to come out of suspension, pool, and hydrolock a cylinder.

                            When I say "hydrolock" I don't mean a cylinder full enough to snap the rods but rather a combustion chamber just full enough such that it causes huge forces at top dead center.
                            .
                            Certainly possible, but as Bruce pointed out the ADI in these engines is regulated and should shut off as power comes back (not to say that it can't fail in the "on" mode, but the pilot "forgetting to turn it off" shouldn't be the problem). Add to that the fact that the engine is mechanically a very low (<7:1, IIRC) static compression ratio. In short- each combustion chamber is very roomy at TDC, its a BIG engine with BIG cylinders, and you'd have to flow an awful, awful lot of fluid for that to become an issue.

                            And Bruce L: As always its awesome to hear insight from someone who's raced a similar airplane and a similar powerplant.

                            Comment


                            • #74
                              Re: Lap Speeds

                              Originally posted by 440_Magnum View Post
                              Certainly possible, but as Bruce pointed out the ADI in these engines is regulated and should shut off as power comes back (not to say that it can't fail in the "on" mode, but the pilot "forgetting to turn it off" shouldn't be the problem). Add to that the fact that the engine is mechanically a very low (<7:1, IIRC) static compression ratio. In short- each combustion chamber is very roomy at TDC, its a BIG engine with BIG cylinders, and you'd have to flow an awful, awful lot of fluid for that to become an issue.

                              And Bruce L: As always its awesome to hear insight from someone who's raced a similar airplane and a similar powerplant.
                              I only know what we dealt with on the Bear as far as ADI regulators.............
                              There are regulators that you turn the switch on whenever and it is solely dependent on MAP to start the ADI flow and increases flow as boost goes up.
                              RB used a regulator that did not have this "switch" When the pump was turned on in the cockpit (at 45" and 2900 RPM) it started flowing ADI immediately and metered it with the boost. As soon as a Torque rise was seen the throttle was immediately advanced to 50"+ The reason for this is twofold:
                              1: removed a potential point of failure.
                              2: the regulator that would turn on/off with boost did not have the volume capacity to feed the correct amount of ADI at top end power.
                              It was installed with the assumption that the pilot was capable of something as simple as keeping an eye on gauges and flipping a switch......... boy were we wrong.

                              I do not know what type of regulator Strega runs.

                              Comment


                              • #75
                                Re: Lap Speeds

                                Originally posted by RAD2LTR View Post
                                Quite a bit more to the point that I couldn't see anything coming off Voodoo, and Strega looked like a jet at 40K feet streaming contrails. I shot these from the hillside.




                                Will
                                Going back to these shots of the vapor coming off the wing, that is the spot where the fuel vent line are on the wing so I'm guessing he's just slightly "off the ball" and venting some fuel overboard???

                                Jason
                                Jason Schillereff

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