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Sep 27, 2019, 11:55 PM
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3D Printed 164mm 2S 18650 FPV


This is an iteration of many different combinations that I have tried. I started with 1104 motors and 3035 props and I could fly but I was lacking power and performance. The 18650 batteries are heavy compared to a LIPO but I want to make a quad that can get reasonable performance and flight time with them. I needed to step up a motor and prop size and ended up with 1408 motors and 4052 props. I am not sure if I can draw the current for acro flying, but hover and punch out tests lead me to believe that this thing will scream.


Specs:
164mm 3D printed PETG frame
EMAX Mini Magnum 2 F4 FC
FrSky R-XSR RX
1408 motors
4052 props
2S 18650 with Keystone cell holder built into frame.
CADDX mini camera

I am still in the testing phase. I have drift in Angle and Horizon modes and I assume it is from vibrations. I need to try some o-rings to dampen the vibrations or detune the ACC with the CLI.

I am having a heck of a time getting telemetry to work. I have TX3 connected to the RX S Port and I have Telemetry enabled in BF and set UART 3 Telemetry to S Port, but I cannot find the sensors on my QX7. I firmware updated everything so there is something that I am missing. I have never used telemetry before so I am stumped for now.

More to come......
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Sep 30, 2019, 03:29 AM
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According to the rule of fifths, for an optimal balancing between performance and endurance, when powered from 2s 18650 (2x45 grams) your platform total weight should be in the 5x45=225 grams ballpark, and motors size should be about 11 grams (45/4).
Start from here you next design.

You have attached a simulation of such design, done based on the closest motor I found when using the limited, non licensed version of eCalc.
Sep 30, 2019, 08:52 AM
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I will have to try that out. Does the ESC matter or should I find one that is limited to 10A? I might just start with a prop swap and see what happens. I am not really going for hover endurance, I am going for longer flight time and a means to use the 18650 INR cells that I have laying around. I also have a bunch of A123 26650 LIFEPO4 cells. These have 50A drain so I might make a go with some of these in a 3S configuration.
Sep 30, 2019, 09:35 AM
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Probably 8A works too, this is the maximum according to eCalc.

Longer hover implies also longer flight times too, at least in the 30-40 kmph speed ballpark, where is the translational lift effect sweet spot.

You should not worry about high current capability, 20 minutes flight means 3C discharge.
Maximum current is an useless figure, who cares about 50 Amps, which means 30C = 2 minutes flight !
LiFePo4 are too heavy, better use lipo instead. They have 90–110 Wh/kg specific energy, compared to 160-180 for lipo, and 220 for LiIon.
Sep 30, 2019, 06:51 PM
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I weighed in tonight and I am at 150gm without batteries and 238gm with. I installed the FC with some o-rings and the behavior in Angle / Horizon was a night and day difference. I get hover at 25-30% throttle and that makes me think that I am a little over propped. I am wondering if I should try a 4032 or a 30 series prop.
Oct 03, 2019, 02:04 PM
Thermite + ice = Big boom.
boaterguy's Avatar
Quote:
Originally Posted by crazifunguy
I weighed in tonight and I am at 150gm without batteries and 238gm with. I installed the FC with some o-rings and the behavior in Angle / Horizon was a night and day difference. I get hover at 25-30% throttle and that makes me think that I am a little over propped. I am wondering if I should try a 4032 or a 30 series prop.
Less pitch will give you hover efficiency gains, despite a possibly deceiving higher throttle position.

Lower blade count is also (usually) more efficient, so you may get some gains with prop experimentation.
Oct 03, 2019, 04:20 PM
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2 blade props seem limited in the 3-4in range so I think I need to stick with 3 blades. I know I will lose some efficiency and speed but I should gain some hole shot and wind handling. I still can't figure out this telemetry issue.
Oct 07, 2019, 01:29 PM
Thermite + ice = Big boom.
boaterguy's Avatar
You can cut the blades off of 4bladers to make 2 blades.

Telemetry wise, I think s.port should be connected to rx, and the flight controller communicates in duplex over that one channel, then you don't use an s.bus connection as well. That's what my impression was, but I've never actually done it. If you go back to the ports tab is it still enabled? If it doesn't like your configuration it will silently disable it.
Oct 07, 2019, 02:16 PM
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I don't believe that you enable the UART you just select smart port in the drop down and don't turn the switch on. I believe the switch is used for passthrough. I have not yet tried RX3 maybe that is the problem. I always thought that telemetry had to be on the TX connection.
Oct 08, 2019, 06:53 AM
Thermite + ice = Big boom.
boaterguy's Avatar
Quote:
Originally Posted by crazifunguy
I don't believe that you enable the UART you just select smart port in the drop down and don't turn the switch on. I believe the switch is used for passthrough. I have not yet tried RX3 maybe that is the problem. I always thought that telemetry had to be on the TX connection.
Telemetry does, but smart port is a slightly different protocol. Either that, or I'm thinking of F.port


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