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Is there an upgrade to Dynam B-26 motors ?

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  • Is there an upgrade to Dynam B-26 motors ?

    Took my Dynam B-26 maiden flight this weekend. Winds were 8- 10 mph. We only have grass runway. Took off into wind with partial flaps. Took her up high and slowed the plane down..It did a wing tip stall and went into a death spiral.. My chief test pilot saved it. He flew for another 5 minutes on the 4s 3600 battery. As he were getting into the landing flight pattern , he turned into the wind. It slowed the plane down and plane went into another death spiral...but at a lower height. Real scary!!!. Again my pilot saved the day. He indicates that the plane is under powered. He wonders if we can put a 5s battery in the plane or change out the underachieving motors or ESCs? Does anyone have experience with upgrading to get more reserve power? My dad flew a mission in Flak- Bait on Sept 5, 1943. He was shot down on Nov 3, 1943 and ended up in a POW camp.
    Attached Files

  • #2
    I'm usually one of the first people to say that a plane needs more power and this case, the plane needs more power. However, having made that statement, I've done nothing to my B-26 and I've flown it in very high winds (over 15-20 mph). With any plane that is "underpowered", one has to fly it high throttle and when banking into a turn, no matter it be into the wind or with the wind, this plane needs full power. That's just the nature of it. Flown this way, I've decided to leave it alone. But if you want to give it more punch, I would suggest staying with 4s power but going with a higher KV motor and bigger ESCs. The trouble with this is that these things weigh more and it will likely upset the balance of the plane. Furthermore, it may be necessary to do some more modifications to make the bigger motors/ESCs fit. Even going 5s will require choosing a smaller battery weight or the balance will be hard to achieve and then, your flight times will suffer. Try flying this plane "pedal to the metal" almost all the time and see how you like it. Anytime you bank it, "give 'er". Only reduce power while in the straight or in a dive.
    I've got a fairly heavy balsa Twin Otter that flies with 900kv motors on 4s and by comparison, the Twin Otter is much faster and way more stable in high winds than this B-26.

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    • #3
      Hi XViper....The field I fly on is grass...we had 2 unsuccessful attempts to take off..used up all of runway. We finally ended taking off with partial flaps pointed into wind. We usually have 8-15 mph wind were we fly. I saw a tread by Bob of borntoolate. He upgraded his motor.

      I used my Hobbico Digital mini -tach to see what rpm on current motor was- motor was powered by 3600mAh 50C admiral pro battery. I read 11700 rpm at 100% throttle.

      I changed out existing motors with Predator 3586 KV850 motor. It is OK to run with existing ESC. I had to also enlarge holes on mounting X-( FMS FMMDJ009) with a 14 drill bit to be able to fit current hole configuration on firewall. I adjusted cowling as motor is longer than original

      I put it back together. I re tached with new motor.. RPM is now up to 24,800. Props are not now counter rotating with the way I hooked them up. I am going back to Bob for some advice as to what color motor lead goes to what color esc to get to correctly work.
      Attached Files

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      • #4
        Originally posted by Ron bolesta View Post
        Hi XViper....The field I fly on is grass...we had 2 unsuccessful attempts to take off..used up all of runway. We finally ended taking off with partial flaps pointed into wind. We usually have 8-15 mph wind were we fly. I saw a tread by Bob of borntoolate. He upgraded his motor.

        I used my Hobbico Digital mini -tach to see what rpm on current motor was- motor was powered by 3600mAh 50C admiral pro battery. I read 11700 rpm at 100% throttle.

        I changed out existing motors with Predator 3586 KV850 motor. It is OK to run with existing ESC. I had to also enlarge holes on mounting X-( FMS FMMDJ009) with a 14 drill bit to be able to fit current hole configuration on firewall. I adjusted cowling as motor is longer than original

        I put it back together. I re tached with new motor.. RPM is now up to 24,800. Props are not now counter rotating with the way I hooked them up. I am going back to Bob for some advice as to what color motor lead goes to what color esc to get to correctly work.
        WOW, you've more than doubled the max rpm, however, that doesn't sound right. An 850kv motor running on a fully charged 4s battery should only be cranking out in the 14,000 rpm range. Your reading for the stock motor is about right at 11,000 rpm.
        Insofar as which color wire goes where, don't worry about it. To reverse a motor, just switch any two of the motor wires. It's that simple.

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        • #5
          Originally posted by xviper View Post
          WOW, you've more than doubled the max rpm, however, that doesn't sound right. An 850kv motor running on a fully charged 4s battery should only be cranking out in the 14,000 rpm range. Your reading for the stock motor is about right at 11,000 rpm.
          Insofar as which color wire goes where, don't worry about it. To reverse a motor, just switch any two of the motor wires. It's that simple.
          I concur, most likely a case of the fat finger typo syndrome
          Warbird Charlie
          HSD Skyraider FlightLine OV-10 FMS 1400: P-40B, P-51, F4U, F6F, T-28, P-40E, Pitts, 1700 F4U & F7F, FOX glider Freewing A-6, T-33, P-51 Dynam ME-262, Waco TF Giant P-47; ESM F7F-3 LX PBJ-1 EFL CZ T-28, C-150, 1500 P-51 & FW-190

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          • #6
            Did you ever get to fly with the new motors?
            Don't just fly--WREAK HAVOC!!!

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            • #7
              After I tried to maiden mine it snap rolled upon lift off at the end of a long runway it took forever to lift off. I found that one of the Skylord escs was running the port motor 9% slower than the other motor across the entire throttle range. The other motor was running 2 % slow at max throttle. So the port motor was 11% slow based on measured voltage times kv. Escs were calibrated max min. Entire program set up for the escs were tried @nd checked no amount of fiddling with timing or break settings helped both esc were returned to factory and recalibrated and the problem persisted and yes I swapped the motors back and forth. I have un glued the nacelles and replacing both escs with a pair that are confirmed or run to rpm/ volt, and track throttle evenly. All my rpm checks were done with no load, no prop and a small disk with reflector on the side for a photo tac.

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              • #8
                Things I have learned the hard way over a number of models include throwing any Dynam ESC or retract straight into the garbage, and replacing them with reliable ones.

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