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Old Jul 22, 2015, 09:51 PM
hoggernick is online now
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Aaaaand another PVC Quad Build

I've embarked upon my first PVC quad. I'm about 1/2 way done and I'm desperate for opinions/critique of what I've got going so far. The flight controller won't be here for a few more days, so I really don't even know if I'm on the right track or not.

Here's what I've got going:

  • 3/4" Schedule 11 PVC, four T joints, approx. 550mm motor-to-motor length
  • Multistar 2212 920kv motors
  • Self-tightening 9x4.3 props
  • Qbrain 4x20a ESC
  • APM 2.8 flight controller
  • Ublox M8N GPS
  • Generic 3DR-compatible 915mhz telemetry
  • 5000mah 3S battery (also have several 2.2mah batteries to try)
  • 600mw AV transmitter
  • Small wide-angle camera (have several cameras to try)

I've weighed it all, and it's looking like it'll be 1400g with the 5000mah battery, or 1220g with a 2200mah battery.

I'm not expecting it to be super nimble, I'm just hoping for a 10 minute flight time, stable loitering and position hold, and ultimately I want to have some fun setting waypoints via an Android phone running perhaps EZGUI Ground Station.

The attached photos depict the inside that has the battery, ESC, and PDB. On top will go the APM, telemetry, FrSky receiver, and GPS donglie. On the bottom will be the AV transmitter and the camera with a gimble. Still haven't worked out exactly what I'll use for legs.

My biggest concern is my motor-mounting. I'm wondering if I should completely bail on that method and pursue the tried-and-true flatten-the-PVC-with-heat method and just bolt through the two layers of PVC.

I'm not too concerned about the weight. I put props on, plugged a servo tester into the ESC, strapped the thing down, gave it some juice, and it sure enough lifted itself at about 50% throttle.

So, am I crazy? Am I on the right track? Are those weights (1400g, or 1220g) out of line for such a quad, those motors, those props? Thanks very much for any advice or critique.
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Old Jul 22, 2015, 10:08 PM
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FWIW, I just discovered the eCalc, so I did my best to plug my stuff into it. here's what it said. The "Throttle at Hover: 74% (linear)" worries me a little. That seems high.
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Old Jul 22, 2015, 10:37 PM
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I may have done something wrong the first time. I reran eCalc, now it's saying 66% hover throttle, which doesn't seem too bad. I really don't know what to make of all those eCalc numbers.
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Old Jul 29, 2015, 05:38 AM
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Quote:
Originally Posted by hoggernick View Post
I may have done something wrong the first time. I reran eCalc, now it's saying 66% hover throttle, which doesn't seem too bad. I really don't know what to make of all those eCalc numbers.
Still looking for help here? I'm pretty much a noob though but I did a pvc quad last year. As far as a mount goes for the motor, I did flatten the ends of my pipe using a heat gun and clamp. If you go back and search the pvc thread , which is a sub thread in "show us your scratchbuilt" you will see that some guys made a jig for a more uniform thread. I found the boiling water kind of sucks, fyi.

You "might" be able to use a x mount and then zip tie the mount to the frame. That will add weight to your frame though. I will say I found the pvc softens around the screw so make sure the head of the bolt is large enough to not go through.

And yes, your throttle seems a bit high. You might be able to shave off some weight from the center plates. The pvc fittings are usually heavy. One last thing, I'm not familiar with schedule 11 is that heavier then 40 or more like thin wall?

If I remember correctly most agree that pvc frames work best under 300mm. That was probably based on thin wall pvc.
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