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1967 short film about the Turbine

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  • #16
    Originally posted by jimclark View Post

    IIRC, the inlet annulus limit was 18 sq. in. in '67, reduced to 15 for '68, then the nail in the coffin after '68, where It was Chapman's 56 more than the turbine methinks, to only 13 sq. in. which just wasn't enuff "breath" to be competitive.

    Bottom line is, they never wanted them in the first place anyway.......
    I believe the annulus limit was 23 sq. in. for '67, and might have been 18 or so for '68. Then, it was reduced to a ridiculously small size after the Lotus 56 was still competitive with the previous limit. For some reason, I want to say the limit finally reached somewhere around 9 inches, maybe not.

    There were several reasons Parnelli was so dominant in '67...the weather was very cool, only about 60 degrees F; Parnelli had a very light touch on the throttle and was easy on the gears(there was no constant velocity joint between the output shaft and the transmission...any other driver would probably have torn up the tranny before half distance).

    For 1968, the weather on race day was very warm...it was about 85 degrees, IIRC. Turbine engines do not like warm and humid weather, and the combination of atmospheric conditions and the smaller annulus made for slow cars because the engines couldn't produce enough power to really be competitive...Leonard only led about 30 laps or so before he went out with the broken fuel pump shaft. Again, IIRC, Pratt & Whitney engineers determined that the fuel pump was the weak link for the turbine engine...if it overheated, the pump would fail, and catastrophic damage would occur. So, they designed the output shaft out of an alloy that would fail if the engine reached a certain temperature. No fuel, no hot engine fire, I guess...Colin Chapman saw what would likely happen if there were to be a long caution period, which there was, and decided that he would have a steel shaft in Graham Hill's car. P&W engineers agreed, but Hill was the only one with the steel shaft. It was a roll of the dice, betting against a long caution, but it didn't matter, because Hill had a suspension failure at half distance. If Leonard had only had Hill's steel output shaft, he'd probably have won. Then, again, the fuel pump might have overheated...who knows?

    The reason the Shelby turbines looked so much like Silent Sam was because they were both designed by Ken Wallis. An interesting bit of trivia, Bruce McLaren and Denis Hulme were the drivers.

    It seems in hindsight that the turbine cars weren't really very practical at Indy. They were finicky and fragile, dependent upon ideal weather conditions and very hard on drivetrain components. Also, turbine throttle lag seemed to be much more of an issue than turbo lag.

    I always felt that in hindsight, USAC made the right decision to end up effectively banning the turbines. They worked well in cool, dry air with 4wd, and that was about it. There never has been a production turbine automobile, and there probably won't ever be. No amount of racing success would ever lead to the turbine engine replacing the piston engine on the highway, and if it did, the Energy Crisis would have killed it anyway.

    I don't have a whole lot of reference material at my disposal regarding facts and figures for turbine engines at Indy, so I was speaking from memory. I may be a little light in some of the details. Please feel free to correct any errors I may have made.
    Tibi Fumus Obsidio Septum Doro

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    • #17
      Originally posted by Tifositoo View Post
      I believe the annulus limit was 23 sq. in. for '67, and might have been 18 or so for '68. Then, it was reduced to a ridiculously small size after the Lotus 56 was still competitive with the previous limit. For some reason, I want to say the limit finally reached somewhere around 9 inches, maybe not.......
      .......I don't have a whole lot of reference material at my disposal regarding facts and figures for turbine engines at Indy, so I was speaking from memory. I may be a little light in some of the details. Please feel free to correct any errors I may have made.
      We were both in the ballpark(ish)......recollecting.

      I gave a quick looksee (good ol' Google) and came up right off with (Wikipedia, of course...):

      "USAC had limited the engine intake area to 23.999 square inches to limit the turbine's power output, but the engine still produced 550 hp. However, drivers reported that it had a three-second throttle lag. In less than a month after the 1967 Indianapolis 500, USAC cut the allowable turbine air intake area from 23.999 to 15.999 square inches and imposed the ruling immediately, although it had been customary to give two years' notice of engine changes.[1] With the reduced inlet area, the maximum lap speed that could be achieved was 161 mph.*" (* for the Wallis car, not the 56)

      I still think I'm in the ball park with the 13 sq in, but it might have been 12.99 or mebbe even 11.99........

      Anyhow......those were neat times in auto racing....you run what you brung and come what may. None o' this crappy "leveling of the playing field".....
      .....A set of rules, build what you decide is the best way to go, and RACE.....
      .....Not parade around in close formation (I chose formation specifically because the "good (actually just artificially close) racing" is virtually "formed") for the sake of the sponsors. (Yes. it's all about money, not competition. The sponsors want more eyes and ears watching their mobile billboards, so close.....errr...I mean "good".....it must be.....)

      Aaahhh.....Real auto racing.....it's gone.

      Last edited by jimclark; 05-08-2021, 09:47 AM.
      "Those were the days my friends. We thought they'd never end....."

      jimclark

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      • #18
        At least you can still complain about it in a daily basis.

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        • #19
          Originally posted by Sea Fury View Post
          Both the Granatelli turbine and the Lotus 56s gave up straight line speed to the more powerful reciprocating-engine cars, but carried more speed through the corners than the others because their AWD systems gave them so much more grip.

          Looks like they did try to change the shape of the inlet though. (This shows Parnelli in the car and Clark in the 56 during testing; sadly, Clark doesn't have long to live in this pic).

          2e1242b7f8d0938f3080692ce8f0f56c.jpg
          The cars didn't handle better because of the 4WD, that was for the torque of the turbine coming off the corners.
          4WD doesn't add "grip" to the tires. It does reduce wheel spin off the corners of only 2wd with all their immediate torque, thus negating oversteer due to wheelspin exitng turns.
          The cornering ability was due to the advanced chassis and suspensions (Rear engined cars were in their infancy at Indy car racing, remember)

          They didn't just try a different inlet to the Wallis car.....they did.
          'Had nothing to do with the regs. changing for the inlet annulus, which is the actual entry point at the front of the engine itself, not the entry to the car. It was round (I think they are to this day on turbines.....'haven't been around any in years....).

          "Those were the days my friends. We thought they'd never end....."

          jimclark

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          • #20
            Originally posted by RS2 View Post
            At least you can still complain about it in a daily basis.
            I appreciate your permission. Thank you!!!
            "Those were the days my friends. We thought they'd never end....."

            jimclark

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            • #21
              Originally posted by RS2 View Post
              At least you can still complain about it in a daily basis.
              I will see your "I can" and add a big "I WILL!"
              Tibi Fumus Obsidio Septum Doro

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              • #22
                Originally posted by Tifositoo View Post
                I will see your "I can" and add a big "I WILL!"
                Yup.
                "Those were the days my friends. We thought they'd never end....."

                jimclark

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