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IMAC prop for DA120

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  • IMAC prop for DA120

    I’ve been using my backup plane all year (EF 104 Extra), and I’m looking for a different prop. I currently have a Falcon 28x9.5 with KS3086 cans. My problem is this prop rips a lot even if I’m easy on the throttle, and I’m paying in the sound scores. DA says a 28x12 will work, but my concern is whether I will still be able to slow down enough to land. As it is, the Extra is so floaty that 1 or 2 clicks of throttle will keep the plane flying the length of the runway.

    Thoughts? I’m not looking for a brand war here. Just a good size prop that won’t rip (or at least rip less). These KS cans are really quiet, but the prop is costing me (4s and 5s for sound scores).

    Dave

  • #2
    I use a Mejlik 26x10 3-blade. Love it for IMAC.
    Rich
    Krzy4RC
    #IAmIMAC
    Newsletter Editor
    @RC Aerobatics Podcast

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    • #3
      A fellow competitor had a 3-blade on his DA120, but he didn’t like it (not enough thrust). He had a 26x12 though. Maybe that was too much prop.

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      • #4
        I've got a 26x12x3 falcon on my 105" Laser230z, DA120 on KS3086 cans and it is a rocket. I love that setup, very consistent and quiet.
        Matt Komar
        - North Central ARD
        - Team AJ Aircraft / Team Makin Bacon
        - 2018 IMAC Worlds Team USA Member

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        • #5
          I compete with it in Intermediate. Could see getting a 12 pitch. But I have not issue with the 10 pitch.
          Rich
          Krzy4RC
          #IAmIMAC
          Newsletter Editor
          @RC Aerobatics Podcast

          Comment


          • #6
            I used to run 26x10x3 Biela on my 3DHS Extra, DA120 on MTW cans. Worked very well for IMAC and 3D flopping. As I recall Biela props have a bit more load than Mej....although it's been many years since I had that plane.

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            • #7
              I have been using 25x12S Mejzlik 3 blade. I tried the 26x12 and was too much load for all conditions. I will agree that is good up to intermediate. If you go higher class I think the 2 blade will be better. I also use the 25x12 Airmodel in my backup plane. Both work well. I get around 6200-6500 RPM.

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              • #8
                I am running a DA 120 with KS 3086 on AJ Laser with Mejzlik 28x12 and I think it is great. Get pretty decent score for sound and it has great power. Before the cans I had 27x11 on mufflers. When I put the cans on it was ripping horribly at half throttle. The 28x12 solved that.

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                • #9
                  Dave, Mejzlik 28x12 2B and I can recover after burying the upline snap. I've tried a large number of Mejzlik 2 & 3 blade props and Biela 3B. Used the Biela for years until I started advanced then went searching. Not as quiet as some of the 3B but definitely better pull.

                  Skip

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                  • #10
                    Thanks, Skip. The 28x12 is where I’m going. Although, there might not be a plane for it to go on for a bit. Last flight of the contest this past weekend was in really high winds. Good gust on landing caused me to Ballon and stall. I got on the throttle but not in time and noticed the gear was damaged. Came back around, killed the engine, but the landing (softest one of the week) still completed the gear being ripped off and the wheels went through both wings. I don’t think I will be able to get it fixed by regionals. I’m either going to go with my 74” Laser, or a club member has offered his 91” Laser.

                    This weekend was strange. First contest I’ve been to that didn’t include you. Looks like Lums Pond had a great showing.

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                    • #11
                      Originally posted by Skip Messick
                      Dave, Mejzlik 28x12 2B and I can recover after burying the upline snap. I've tried a large number of Mejzlik 2 & 3 blade props and Biela 3B. Used the Biela for years until I started advanced then went searching. Not as quiet as some of the 3B but definitely better pull.

                      Skip
                      I agree. It is the best choice for Advance class. I fly Intermediate. I use 3b because better downline breaking and noise control. It is clear a problem when doing upline snaps with the 3b prop. I have tried and does not look good.

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                      • #12
                        I might be the person Dave mentioned with the Falcon 26x12x3, on canisters. I was flying Basic then, Sportsman now. I bought it more for noise than anything else, and it was almost too quiet, as I couldn't hear it at idle in the traffic pattern. When I broke that, I went to a 28x10x2 that I had on hand. I got more thrust, a little noisier (still relatively quiet), less downline braking and less constant speed through maneuvers. But what really surprised me is the controls felt crisper with the 2-blade. I don't know why it feels that way, but I like it.

                        The increased thrust is overkill for Sportsman so it seems the braking and sound make the 3-blade better for Sportsman. But the intangible feel of the 2-blade is making me want to stick with that. It's just more fun.

                        Interesting that Rich W. is using a 26x10x3 Mejzlik compared to my Falcon 26x12x3 which is the size recommended by Falcon when I told them what I was flying. Has anyone tried both?
                        Last edited by Steve Pennypacker; 09-16-2020, 05:26 PM.

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                        • #13
                          For reference, the plane is on the heavy side, 33# dry, 36# wet, on pipes. I checked the prop box last night and this is what I have tried. Really wanted a 3B to work.

                          Mejzlik 25x12Sx3
                          Mejzlik 26x10THx3
                          Mejzlik 26x12Nx3
                          ​​​​​​​Biela 26x10x3
                          Mejzlik 28x12x2
                          ​​​​​​​Mejzlik 29x10Sx2

                          Performance wise the best 3B was the 25x12 but the 28x12 2B is noticeably stronger. The Biela is the quietest but it lugs.

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                          • #14
                            Your plane is definitely on the heavier side but I wish I could lend you my Falcon 26x12x3. Mejzlik props are great (using a 28.5x12x3 on my DA200) but they tend to be heavier and less efficient than Falcon. I've seen guys 3D with the Falcon 3 blade without any hesitation on pullout power.

                            ​​​​​​I'll be flying my 105" AJ Laser with the Falcon 3 blade at our final contest of the year in Advanced and I have the absolute confidence that it will keep up with my bigger 123" Laser/DA200 setup.
                            Matt Komar
                            - North Central ARD
                            - Team AJ Aircraft / Team Makin Bacon
                            - 2018 IMAC Worlds Team USA Member

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