First Quad DIY build considering T4 quadcopter

Discussion in 'First Build' started by voidstar, Jul 22, 2018.

  1. voidstar

    voidstar Member

    I've heard of the "melting" print problems -- yikes, even just keeping them covered (out of direct sunlight thru a window) might not be enough? I try to keep them covered by a towel or box at least, but might also need to keep a window cracked. Or you know how Insight's have those solar roofs, to keep an internal fan blowing while away from the car -- those need to become standard :)

    I did notice the bundle of bullet connectors truly felt "heavier" just holding them. But yes, "swap-ability" is why I kept the black plastic signal connectors for the ESC's also -- if I was going to make them swappable, I need the 5 motor+power cables on bullet connectors, and the 3 "signal cables" (well, lower power and signal) also on their own connectors. 30A was probably overkill (Brendan used 20A on his original). I'm not sure how the Phantom or Mavic get such long battery life -- like over 25 minutes? I'd assume mostly very efficient motors?

    As for the landing gear -- if I keep them "straight down", yes, they tend to catch. So I found that pivoting them like 45degrees before a launch, they work a lot better. If they were slightly larger, they might also work as "prop protectors" (for walls/structures, not so much for trees). And I do think ABS may be the way to go for the legs/landing gear, and PLA for the arms. For the legs, I used a glue gun to better secure the ends.

    Also, hard to see in the pictures, but I added a sort of "integrated roll bar" into the top body piece. About 10mm thick rib around the center of the body. Then a similar "anti-crush bar" up front behind the camera, another 7mm thick bar. These keep that top a bit more rigid if it ever does get stepped or pressed on (in one of the crash-flips, I had the camera get sheared off since the top body came lose) -- without the reinforcement, that would tend to pop-out the screws securing the top (which I am also looking for slightly longer screws for that, they're M3 I think). Not that we're going for BattleBots, but this is kind of a tank :)
    GJH105775 likes this.
  2. wafflejock

    wafflejock Well-Known Member

    Still have to battle gravity and the concrete if you're flying over that :)

    Regarding plastics, PETG is a nice alternative as well, sits somewhere between PLA and ABS in terms of rigidity and strength. PETG is like coke bottle material (PET typically I think) so it has more give to it than PLA but doesn't warp while printing nearly as much as ABS (only down side I've experienced with PETG is some more stringing, or dripping, than usual during what should be filament free moves).

    Regarding DJI they claim 'up to 23 minutes' which means ideal conditions hovering not actually flying since any amount of moving forward is energy you aren't spending staying in a hover and I assume this is something like 20ft off the gnd hovering not climb to 400ft then hover against the wind. They also say they have a 4S 4480mAh or so battery which is 17Wh total energy or so, can compare with your battery Wh to get some idea of total energy capacity in the battery. I think all BLDC motors are something like 80-90% efficient so I don't think they are getting much more out of that.
  3. voidstar

    voidstar Member

    Testing with a 4S lipo has worked out great!

    Without the (heavy) landing gear, the 3S still works -- but perhaps barely (or maybe its the props?). Anyhow, the 4S has been night and day difference -- HOLD and LOITER modes are working great (no more weird vertical oscillation).

    First FPV field test! I accidentally ordered a 6000mah 4S instead of 4500mah, so it was too tall to fit into the battery compartment. But to just test out the electrical aspect, we strapped on the 6000mah. The EagleTree Current Sensor is rated up to 6S; it seemed to be regulating the 12V and 5V paths just fine, and giving that little extra "ooomphf" to the motors to stay steady.

    The camera is bouncy. Since everything else is checking out well, that's the part I'll address next: dampening for the camera.

    Last edited: Oct 15, 2018

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