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Help needed with ESC on 70 mm Mirage 2000 EDF

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    Help needed with ESC on 70 mm Mirage 2000 EDF

    Hello there,

    I bought an EDF kit from a bro (some Chinese brand) which came with a 64 mm EDF fan. I upgraded to a 70 mm EDF can with 7 blades, and mated it with a 4800/kv motor from HK. Wanted to run the jet on a 2200 mAH 3S lipo.

    I think that this is the kit: http://www.edfplanes.com/exrcmi2064ed.html

    I tried a 50 AMP ESC from HK - when going to full power (which is a lot), it only lasts a few secs and then drops power quite substantially. Maybe I have ruined the ESC, maybe it was low quality (=fairly cheap). Why does this happen?

    So, my questions for you guru's out there are:

    1. For a 70 mm with 7 blades, how many amps should I be pulling on full throttle, or 50% throttle?
    2. What ESC do you suggest would be the best? Does anyone have one they would like to sell to me?
    3. How long a flight can I get from a 2200 mAH 25-40C battery?

    Thanks,

    Nomi
    81286984

    #2
    Going from 64mm to a 7 bladed 70mm is a massive huge step.

    Not only did you fail to consider the size of the 70mm, but the number of total impeller and it's pitch surely could've put a stress on the ESC and possibly the motor too.

    You could've ruined either the ESC or the motor, burning out either.

    The 4800kv on the 64mm is already optimal and it is taxing even for a 2200mah 3s. It should draw optimally around 30-35 amps.

    Your setup surely exceeds the 50amps drawn. The motor at 4800kv is not suitable for a 70mm. It is more for the 55-64mm range of edfs that has 5 blades.

    This indicates you have no experience with EDF. Have you flown an EDF jet before?

    Comment


      #3
      Yes, flown plenty but always PNP/ARF kits where the only electronics I needed to add was the RX! I actually am a "glow" guy who moved to the electric side recently. Running a Phantom on 4S 2200 C (with a 64 mm) where 50 power is more than enough and I throttle to 100% in short spurts. Also flying a Radjet - so speed and flying ain't the issue at all.

      I am afraid that the mods that I had to go on the fuselage to fit in the fan unit is a rather permanent set up, as in I cannot get the fan unit or motor out without ripping up the fuselage. Can I adjust the throttle control electronically to go to up to 50/75% power only so get down to 30-35 amps?

      Comment


        #4
        Bro i think you definitely need to upgrade your esc to 80amp to be safe. Also battery for 3S 2200 need high discharge rating. a 20-25C rating battery will surely make it bloat fast due to stress and heat.

        Like the other bro said, your motor set up of 4800kv for a 70mm 7 blade is overkill. Either motor or esc will go first.

        You can't adjust by changing parameters on your tx.

        Comment


          #5
          No, that would put a stress on the esc and motor. It does not work that way.


          At the very least, you need to change the motor into a 3000kv one meant for 70mm edf for a 4s.


          Since you want to use a 3s, maybe 3300-3800kv range is what you're shooting for.

          Hobbyking - the world's No1 Online Hobby Store. We stock a huge selection of RC products from Planes right through to Drones and all accessories. Visit Us Today.

          Comment


            #6
            It indicates that you have no experience with 70mm setup.

            Unless you are flying Guanli EPS jet which is much lighter, 3 cell 3300-3800kv is badly underpowered for any scale 70mm jet

            Comment


              #7
              Originally posted by Slamdunk View Post
              It indicates that you have no experience with 70mm setup.

              Unless you are flying Guanli EPS jet which is much lighter, 3 cell 3300-3800kv is badly underpowered for any scale 70mm jet
              Wrong. It indicates you guys are spoilt flying heavy EPO factory moulded jets that require so much power to get off the ground.

              70mm 7 blade with 3300-3800kv in 3s is enough thrust for sports flying. Keyword is 7 blade, not 5 blade.

              If you've built scratch built edf you'll realize it's actually much lighter than what you buy off the shelves and these setups are more than adequate.

              Besides, the ts is putting a 70mm 7 blade into a kit made for 64mm, so it should have no problem flying that kit.

              Hobbyking - the world's No1 Online Hobby Store. We stock a huge selection of RC products from Planes right through to Drones and all accessories. Visit Us Today.

              Comment


                #8
                To be sure about the current draw, you can get a watt meter from hobbyking (it is not too expensive) to measure the amp draw during full throttle. From there, you will have an idea of the ESC you need. I have flown an EDF design for 70mm with a 64mm fan and a 60A ESC, 4s... I don't think I can go any lower than 60A. The batt is very hot after that. Thanks for reading.

                Comment


                  #9
                  Originally posted by jman View Post
                  Wrong. It indicates you guys are spoilt flying heavy EPO factory moulded jets that require so much power to get off the ground.

                  70mm 7 blade with 3300-3800kv in 3s is enough thrust for sports flying. Keyword is 7 blade, not 5 blade.

                  If you've built scratch built edf you'll realize it's actually much lighter than what you buy off the shelves and these setups are more than adequate.

                  Besides, the ts is putting a 70mm 7 blade into a kit made for 64mm, so it should have no problem flying that kit.

                  http://www.hobbyking.com/hobbyking/s...Assembled.html
                  Almost all foam planes available are EPO foams now, EPS is history.

                  7 blades on 3800kv motor on 3cells, can you tell me how much amp is being drawn and what Lipos you used? Do you have an AMP meter?

                  Comment


                    #10
                    https://www.youtube.com/watch?v=-8iP...layer_embedded

                    The underpowered setup that you have recommended is only good for this kind of light weight EPP scratch built planes.

                    Try this setup in an RC Lander F-16 with alloy retracts and you will know understand why.

                    Comment


                      #11
                      Nopes, still many foam planes are in EPS if they're very large. Weight is still issue. For scratchbuilders we don't use EPO since that foam is only injection mouldable and not available in sheets. As I said, you're spoilt for heavy EPO bought kits and if you bothered to read the TS post, he's putting a 70mm 7 blade and wants to use a 3s lipo in his built for 64mm kit. Do not try to derail this topic and turn it into an ego trip for yourself personally. The setup is fine for his kit and even scratchbuilders.

                      Comment


                        #12
                        Originally posted by naumanahmad View Post
                        Hello there,

                        I bought an EDF kit from a bro (some Chinese brand) which came with a 64 mm EDF fan. I upgraded to a 70 mm EDF can with 7 blades, and mated it with a 4800/kv motor from HK. Wanted to run the jet on a 2200 mAH 3S lipo.

                        I think that this is the kit: http://www.edfplanes.com/exrcmi2064ed.html

                        I tried a 50 AMP ESC from HK - when going to full power (which is a lot), it only lasts a few secs and then drops power quite substantially. Maybe I have ruined the ESC, maybe it was low quality (=fairly cheap). Why does this happen?

                        So, my questions for you guru's out there are:

                        1. For a 70 mm with 7 blades, how many amps should I be pulling on full throttle, or 50% throttle?
                        2. What ESC do you suggest would be the best? Does anyone have one they would like to sell to me?
                        3. How long a flight can I get from a 2200 mAH 25-40C battery?

                        Thanks,

                        Nomi
                        81286984


                        TS I just checked your kit. It says flying weight around 520g. If you can get your entire build up with the 70mm for under 700g you should be good to go. At least a 0.8:1 thrust to weight ratio is possible.

                        Comment


                          #13
                          For those interested in 3s and a similar 3950 kv motor setup amp draw for 70mm edf, refer to this thread. http://www.daddyhobby.com/forum/showthread.php?t=80590

                          Comment

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