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Prop thrust gain per inch?

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  • #46
    Complicated nawwww! I went from fixed pitch pawnees to 1300 hp AT-602 five blades props designed for kingairs, i did see and experimental 4 blade with wide blades and the figures were outstanding, i guess what i am saying is that a prop designed with over 200 knots in mind isnt what would be ideal hauling 630 gallons off a half mile strip i come to the conclusion that mission parameters is what one designs for, being on fixed income i have to now use my head instead of my pocket book, i am looking at starting a hornet but your limited to certain engines, i have plans for a parson 2 on which i have seen everything from 582 rotax to mazda rotory to lyc 0-320 i am thinking the just overhauled 1.3 geo tracker i have maybe just the ticket with redrive of course, anyway my mission is being able to pullit out of carport taxi to the field next to house and takeoff, saving hanger or storage costs, us crpdusters are an outlaw bunch.

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    • #47
      My 230 HP Subaru has a 5 bladed warpdrive prop,I went to 5 blades because I ran out of pitch on the 4 blades

      the extra blade did the job,I am now pitched for 5,100 rpm on takeoff.
      Best Regards,
      Eddie Sigman,Polvadera,nm
      (575) 835-4921

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      • #48
        The complexity was beyond me, so when pitching the prop on the Hornet, we had the 503 DC DI with the B box and a 62’’ inch 3 blade Warp (the guy at Warp advised we could go to 63’ with the 503 but said an inch less would be better), we tied it down and then began pitching the prop to give us 6500rpm with WOT.

        This it was said would then be around 6800 RPM/redline in the air in cruise. Then did a thrust test and got 319lbs. This was not bad when we had only five galls, but when I topped of with ten at Zephyr Hills in the summer then gave a very anaemic performance. Then again our machine was heavy at 330lbs and me at 200lbs.

        I regret to say that I am very happy with a spreadsheet or tables that work it all out, and grappling with math was never my particular turn on, being far happier sitting fat dumb and happy with a stick and peddles to play with.
        Last edited by Resasi; 07-22-2017, 11:56 AM.
        Leigh.

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        • #49
          Post #37
          Vance:
          The propeller can’t blow well if it doesn’t suck well.
          Vance, are you saying that: When someone is blowing up my tailpipe - they are really a big sucker?
          David McCutchen
          615-390-2228
          Bensen B7m, 90 hp Mac
          Dominator Tandem, 100 hp Hirth
          Kolb Mark III Classic, 80 hp Verner
          Certified - Advanced Master Beef Producer
          EAA Member #0511805
          PRA Member #28866
          PRA Chapter 16 Member
          Secretary & Treasure - PRA Chapter 16
          President / Sylvia - Yellow Creek Volunteer Fire Dept.
          Chairmen - Dickson County Veteran's Day Committee
          Volunteer - Dickson County Airport Aviation Day Committee
          2 busy 2 No!

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          • #50
            Originally posted by Gyro28866 View Post
            Post #37
            Vance:


            Vance, are you saying that: When someone is blowing up my tailpipe - they are really a big sucker?
            No David, I was writing about propellers.
            Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

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            • #51
              Originally posted by Dan R View Post
              I have a question? I had airboats and read all the discussions on props also i am a retired agpilot with about quesstimated 30,000 hours, does prop width have an effect on thrust or push in airboat terms, i noticed that the 72 inch props had a bad effect on thrust lines, i am trying to get the materials to start building a gyro using the geometro engine and maybe making a prop based on what airboats use (wide blade wood prop) maybe around 60 inch diameter, the air speeds are some what similar to an airboat, just pondering thanks
              Wide chord props end up causing drag when power is pulled in flight. Several accidents / mishaps have been blamed on wide props. Airboat is NOT a gyro.

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              • #52
                So a 72 inch three blade prop has less drag than a 60 wide two blade prop both are spinning disks i will experiment this by hanging a board equaling each type of blade out my truck window and measure the differance, i remember cessna agtrucks on some models had a shorter blade we thought wow we gotta have the long blade version it came down to very little difference in take off and carrying a load but we did notice with the long blade prop cruise speed dropped off and noise levels were ear splitting.

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                • #53
                  Originally posted by Jean Claude View Post
                  How did they measured the thrusts during flight ?
                  With diameter 63" and 52 HP, Maximum theoretical efficiency is 0.7 at 50mph.
                  According NACA tests, classic propeller gives at best only 0.63, because the loss by friction on blades and rotation of wash.
                  This gives a thrust of 110 kg.
                  If extra 25 kg, then his efficiency would be 0.77
                  Probably magic propeller !
                  It was a static pull.
                  Yes, of course - this is a magical propeller.
                  Attached Files
                  Best regards, Vladimir Meglinsky
                  My site: http://propeller.simplesite.com/

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                  • #54
                    Originally posted by Jean Claude View Post
                    How did they measured the thrusts during flight ?
                    With diameter 63" and 52 HP, Maximum theoretical efficiency is 0.7 at 50mph.
                    According NACA tests, classic propeller gives at best only 0.63, because the loss by friction on blades and rotation of wash.
                    This gives a thrust of 110 kg.
                    If extra 25 kg, then his efficiency would be 0.77
                    Probably magic propeller !
                    Just for the record... This paper describes a clever method of deriving, among other things, the real efficiency of a propeller when working on a light airplane. For the single-engine 'Luscombe' the figure is 0.62

                    ​​​​​​https://engineering.purdue.edu/~andr...-46372-872.pdf

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                    • #55
                      70 " 3 blade IVO Magnum on 2.5 Subaru.......Thrust numbers to follow....

                      From neutral position I have reduced pitch 3 full turns out of a possible 6.5 to obtain 5250 motor rpms.
                      Attached Files
                      Happy Flying, Chris S.

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