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    #76
    yeah edf is a black art it self... so far i have learn

    1) edf - suck juice does not equal to more power.
    2) need a good air frame to make use of it.
    3) intake and exos very important.
    4) more of less blades does make a different.
    5) edf always less efficient then normal prop planes.
    6) edf has no torgue roll effect only .. not enought thrust causing a failed launch.
    7) most good edf airship needs a bungee to launch or power launcher like hawkeye himself.
    8) most good edf setup cost a bomb. hehehehe
    i'm a rc sotong. And i know nuts about it.

    Comment


      #77
      I am all for discussion of the EDF further.

      It is funny, but I did not feel any tension or whatsoever, just differing opinions, I do not think any heartbeats are raised yet.

      Vortices, I appreciate your intention to make things more interesting by offering a prize but I would like to recommend you to stop doing so (a bit vague but if I understand correctly). If you allow me to side track a little bit, I think you should participate in a thread like any other people, being a expertise or whatever, but definitely NOT as a vendor. A forum won't be that great anymore if too many vendors start doing the same thing and offer prizes in discussion, it will be labelled easily as marketing bid only. So I will really appreciate if you can define your role in the forum a tad more clearly and stick to it. Mixing both not a good idea.
      Stop looking for a gyro in my plane, they are all in the head.

      Comment


        #78
        I am very sorry edmund, I suppose the joke prize was not obvious. It is just a joke, Recognition and Free air. I politely apologise.

        After stating what I said, I had forgotten, again, statements can be misintepreted.

        cheers.

        Comment


          #79
          Originally posted by Vortices
          I am very sorry edmund, I suppose the joke prize was not obvious. It is just a joke, Recognition and Free air. I politely apologise.

          After stating what I said, I had forgotten, again, statements can be misintepreted.

          cheers.

          Hey Vortices, if you mean it as a joke, accept my apologies then. My bad. I had difficulty telling individuals and vendors apart.
          Last edited by edmond22; 12-07-2007, 09:10 AM.
          Stop looking for a gyro in my plane, they are all in the head.

          Comment


            #80
            Okok..pardon me if this is a newbie comment.

            so generally its safer to have Higher KV motors on smaller blade area surface and Lower KV motors on bigger blade area surface. To produce the most maximum trust without burning ESC and overheating motors.

            and.. lets say we use the same motor ,same esc,same batt on 2 kinds of EDF

            55mm and 68mm EDF 6blade each.

            55mm will have less thrust but draw less amps :more RPM

            68mm will have more thrust and draw more amps :less RPM

            right?
            Build it
            Fly it
            Crash it
            Fix it

            Comment


              #81
              Originally posted by viper1990
              Okok..pardon me if this is a newbie comment.

              so generally its safer to have Higher KV motors on smaller blade area surface and Lower KV motors on bigger blade area surface. To produce the most maximum trust without burning ESC and overheating motors.

              and.. lets say we use the same motor ,same esc,same batt on 2 kinds of EDF

              55mm and 68mm EDF 6blade each.

              55mm will have less thrust but draw less amps :more RPM

              68mm will have more thrust and draw more amps :less RPM

              right?
              With my limited knowledge, I can say that you are quite right to a certain extend and that's assuming the 2 EDF units has the same fan pitch and blade design. In this case, the comparison is between 2 similar units with only fanns of different diameter alone.

              However, if your motor has reached a point where it has overloaded with the 68mm fan, the current draw will shoot up, and both static thrust and rpm will drop. Sometime, the motor in this condition is referred as stalled.

              Comment


                #82
                Viper,

                Here's some useful links for you. In deciding for a suitable power setup for my plane (edf or not), I usually go for a watt per pound rule to decide how I want the plane to fly (aerobatic or docile), of course the resultant wing loading or cube loading (latter is better) will also influence the charateristics of the plane. I also use the watt hour per pound rule to decide what kind of battery I need. To aid all of these calculations, I use motocalc and some of my own calculations to arrive at a few setups and pick the best for my application from there. The software and some research on the internet helps me narrow down on what kind of motor and EDF/ prop I should go for with which batteries. I normally settle for a 4 watt hour per pound duration and strive for a 150 watt per pound and more setup for my EDF (my desired flying style). So in this case, the KV of the motor matters to me in terms of whether it is suitable to mate the EDF so that it would not burn or push the fan beyond its intended usage, not so much for generalising and think a certain KV is ok for certain fans, that would be too general and very blind in arriving at your preferred style of flying. Seriously, trust me, I encountered too many "lao jiao" who will often comment to me "hey your motor is too high a KV for your prop or EDF" or your wing is too heavy to fly, they will stop patronising me automatically after seeing the setup in question scream very loudly across the sky and not burn. The reason for this is very simply just ample research, REAL scientific calculations and keeping your usage to within stipulated limits. So investing in a wattmeter and tachometer is a necessity to see what your power setup is doing and you will automatically be very accurately find out your RPM, current level, watts and predict if it is really higher or lower thrust


                Quote from http://www.hangar-9.com/Articles/Art...rticleID=1488:
                "for a trainer-type model to take off and cruise around, it would require a system that generated about 50 watts per pound. Basic aerobatics require 70 to 80 watts per pound. To achieve very good aerobatic performance, the power system must be capable of producing 100 watts per pound. Today’s 3D-capable models require systems that pump out more than 140 watts per pound."

                Example of a research material
                Electric RC Jets - Brushless for Wemotec minifan? - Looking for some advice on two things: 1. Looking for suggestions to replace the speed 480s with in Wemotec mini fan units in my scratchbuilt A-10 (~53 w/s) with brushless motor(preferably as cheap as possible, with increase in thrust). I'll acquire speed controls as



                Useful Guides
                Matching power system to airframe
                RC Groups - the most active Radio Control model community: electric and fuel rc airplanes,rc helis,rc boats and rc cars. Features discussion forums, blogs, videos and classifieds.


                Watt per pound
                RC Groups - the most active Radio Control model community: electric and fuel rc airplanes,rc helis,rc boats and rc cars. Features discussion forums, blogs, videos and classifieds.


                Watt-hours per pound
                RC Groups - the most active Radio Control model community: electric and fuel rc airplanes,rc helis,rc boats and rc cars. Features discussion forums, blogs, videos and classifieds.
                Stop looking for a gyro in my plane, they are all in the head.

                Comment

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