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Thread: The new QAV500 FPV Quadcopter frame by Lumenier (formerly fpvmanuals)

  1. #361
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    I guess I always looked at it like going up hill with precision, like a rock crawler but I don't have much experience with quads. The specs show this motor pulling over 1000 grams with a 1045 prop at 4c, what kind of thrust would you expect from a motor like this? It weighs about 80grams itself
    Last edited by logicwins; 21st June 2012 at 10:59 AM.

  2. #362
    4kg of thrust at zero prop speed isn't going to get you anywhere. just like insane amount of power on a low gear aren't going to get you anywhere either. 4000g of thrust on a 1200kV motor is "twice as useful" as 4000g of thrust on a 600kV motor (assuming same prop). makes sense?

  3. #363
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    I am no engineer so I am probably not understanding this properly. I see 4kg of thrust as being equal to 4kg of thrust no matter the KV of the motor. I could see the rate at which a motor can adjust this thrust as being a positive to a quad, is that what you are talking about?

  4. #364
    Banana Drone Flying Monkey's Avatar
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    Maybe I can help here. Assuming the same thrust at max throttle, you have a 600kv motor and a 1200kv motor.

    The 600kv motors will spin at half the rpm and swing a large prop (like 11" or 12") efficiently and have a lot more torque so it will change rpm quicker. So this quad will be perfect for aerial photography... spending most of its time hovering and cruising around taking pictures or video. It'll handle the wind really well and be very stable and smooth. But its no sports car, if you put it in a full throttle climb it will run out of rpm long before the 1200kv motor and thusly its climb airspeed will be pithy.

    The 1200kv motors on the other hand, have less torque BUT spin a much smaller prop (like 8") and the prop will have less weight, less inertia and the motor will be able to change rpm about as quick. This quad will have excellent aerobatic performance, fast climb rate but short flight times. Juz does some amazing aerobatics and some insanely fast climbs with his quad (on 1200kv) but his flight times are around 4 minutes, lol. He doesn't mind cause he's pretty exhausted after his flights And this ship might be better for range attempts cause you'd have a faster forward speed and make twice the range.

    So I think thats what Trappy means when talking about the 600kv quad being stuck in 1st gear and the 1200kv being in like 3rd or 4th gear...
    "You can't take the sky from me"

  5. #365
    precisely Flying Monkey. thrust is only the amount a motor can carry, not at which speed. so therefore thrust determines the acceleration, kV determines the speed range. Juz just pointed me to some frickin' sweet motors that I didn't know I had (LOL) so that's what Perna is going to test this weekend. I'm excited!!

    btw, one good thing about high kV motors is the higher vibration speed, which is easier to absorb and filter. Win-win-win in my book. If you're after flight time you're better off flying getting a plane or a heli. A quad is supposed to give you that tingling sensation in your asscrack every time you "flick" the throttle.

  6. #366
    Banana Drone Flying Monkey's Avatar
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    Quote Originally Posted by Trappy View Post
    Juz just pointed me to some frickin' sweet motors that I didn't know I had (LOL) so that's what Perna is going to test this weekend. I'm excited!!
    Any hints? Or a link to its product page?
    "You can't take the sky from me"

  7. #367
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    Ok that makes sense, thank you for the explanation. I am looking forward to seeing how this QAV500 flies, it seems the motors are a good match for the goals of this frame.

  8. #368
    MT2216's. I got the 900kV version here. Juz pointed me to a 1100kV version. As logicwins pointed out, they may not be a very good match for the QAV500 - not enough power and way too much kV. but they may just be what we've been looking for for our own frame. In any case, there are also some other motors of this caliber that may be better suited for the QAV500 from RC Tiger - unless you're doing AP work.

  9. #369
    Lumenier.com timnilson's Avatar
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    From my point of view:

    1.) While the NX-4008 are very low KV motors at 620kv, they are also very wide with a 40mm stator -- low KV and wide stator translates into high amounts of torque. As long as the top speed of the motor (at full throttle and max prop RPM) is adequate for your flying style, then you want the highest torque motor for everything else below full throttle so that any throttle change is immediately translated to the prop changing RPM. It is that high amount of torque that will make the multi-rotor feel very responsive.

    2.) This responsive feel from a high torque motor is amplified by a stiff frame. With a very stiff frame any change in throttle and resulting prop torque goes straight into the prop moving air -- not flexing the frame. Same concept as a stiff carbon-fiber bike frame -- if you punch down on the pedal, you want no flex in the frame but to translate the push of the pedal immediately into the wheels propelling you forward. The QAV500 is very stiff and you will benefit from high torque motors as you will immediately translate the prop changing RPMs into air movement.

    3.) My flying style is such that I rarely fly at full throttle -- only occasionally for quick changes in altitude, to fly the occasional high speed line, etc. If your main objective is to fly at full throttle for longer periods of time, a higher KV motor might make more sense then a low KV motor with lots of torque.

    I know Trappy disagrees on this, but I am a big fan of wide 40mm stator ('pancake') motors and have been flying them successfully on my tricopters and the QAV500. The top speed the NX/FM-4008 produce is plenty fast for me, but that's a subjective statement. So I don't think it's a matter of being right or wrong -- just personal preference.

  10. #370
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    Ok great, now please tell me that mine has shipped.. I have a baby due any day now so the sooner the better for me because I am not going to have much time to build it ! In seriousness, thanks for the explanation. As long as this can fly at 20-30mph I will be fine.

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