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    Trex short flight times?

    Hi,

    I have a Trex V2 with Align 25A ESC and LF400 2800kv motor running on polyquest 3s1p 1500mah packs... I have 3 of these which work fine on my brushless planes.

    After about 3-4 mins in a hover my chopper will lose power quickly, with the the motor continously throttling up and down (like a sine wave) on its own with the stick at full power.

    The ESC is set to mid timing, 70% voltage cut-off and no brake of course.

    Would anyone please offer any pointers or help? Greatly appreciated. Thanks!

    Nicholas

    #2
    Whats is the current draw for your heli? When you mentioned polyquest 1500mah, what kind of discharge are we looking at. The Align power system is drawing close to 20A the last time round we check on normal setup. Is the batt capable in supplying this current draw? Appreciate if you can prrovide this info.



    Mike

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      #3
      Hi the polyquest is rated 10 to 15C... thats about 22.5 amps max. I don't know my amp draw don't have the means to measure that.

      Comment


        #4
        Hello Lame_cow,

        Check your polyquest cell if all cells are the same voltage. if not balance it.

        Secondly, spin your main gear, it should be smooth, sometimes, the drive too tight causes higher current draw, therefore short flight time.

        If your polyquest are healthy, u should get 9 to 10 mmin flight time.

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          #5
          I balance the batteries every 3 or so flights...

          In tight do you mean the main gear or the tail belt? The belt is not too tight i think the main rotors can be spun in reverse (due to one-way bearing of course) rather freely.

          Would anyone know what the ESC timing means? low-mid-high, i've read that generally high is for power and low is for 'economy', and align motors use low/mid settings.

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            #6
            Don't mind me asking - how u do your balancing?

            Tight as in pinion to main gear, and tail rotor drive belt. When u spin the main gear either directions, it should move easily with little effort.

            If u are using outrunner motors ie Align, the timing should be set to high. if timing too low, your motor don't generate enuf torque, u end up increasing your pitch. More pitch means more amp draw.

            What is your pitch at half stick?
            What is your throttle setting?

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              #7
              K i've changed the blades to the wood ones from the ABS... these produce more lift at similar settings, increasing flight times.

              Upon reading up at runryder i have also changed the pinion on the 2800kv 400LF motor to 15T one... has greatly helped to increase headspeed which i felt was rather low on the 13T. Not much change to flight times.

              Tightness on gears and belts should be ok... All can spin with relative ease.

              As for the ESC timing i use mid... i'll try out high and find out the difference.

              Oh and one more thing... after the esc cut off kicks in i check the battery voltage... its about 10.5V(no load) for my 3s1p battery. What is a acceptable range of voltage that a lipo batt can be discharged to?

              Thanks a million
              Nicholas

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