First Quad DIY build considering T4 quadcopter

Here is what I meant about the propeller heights (these are the two fronts). The issue seems to be in the collar (leaving the motors in place, I can swap the attachment components and reverse the height). The drone seems a little overly sensitive in pivoting (rotating) and maybe it's related to this?

Printing new lower body now, then have room to secure a top piece with 6 screws next.

height_delta.jpg
 
Here is what I meant about the propeller heights (these are the two fronts). The issue seems to be in the collar (leaving the motors in place, I can swap the attachment components and reverse the height). The drone seems a little overly sensitive in pivoting (rotating) and maybe it's related to this?

Printing new lower body now, then have room to secure a top piece with 6 screws next.

View attachment 4452
I've done test on prop height to see if it affects stability and determined that it might cause a little pendulum effect when a more drastic difference is present. Other than that it wasn't anything too bad. That 1/4'' shouldn't be very noticeable. Sadly my video from these test is back in Ohio. You might try top mounting your battery to get the center of gravity closer to the center of the props on the Z axis. Some arm flex can cause this as well. You might design the frame to allow carbon fiber inserts. I've had pretty good success with mixing 3D printed frames with carbon stiffening rods. If it isn't a structural problem I'd play around with rates and PIDs.

Could we see a video of the problem?
 
GJH105775: Oh, I'm not sure if it's is a specific problem. I was able to control and move around, I just had to be delicate on the movements -- making the piloting a bit "tense" and not relaxed (I felt I almost lost it about 3 times during the first flight). I'm a new pilot and new equipment, it could still be a number of things (weight balance for instance). But I was just curious about other thoughts on the propeller height delta, and whether it was a "normal" thing or not.

Here is the first flight video!! (ok, technically it's 2nd flight -- but 1st flight was just a basic up/down test, to see if the motors even carried the weight!) This flight is a little boring, but I wanted 10 minutes flight time just to see how warm things got -- and they do get a bit warm!

(yes, it ends with a flip over, but nothing was damaged -- so I'll just say it was a test of the Vectors auto-disarm feature :) )
 
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What about the casing? for the circuits above the quad

Here is what I came up with for arranging the ESC's on the bottom side. I know experienced builders will be "ROFL" -- yes, like 90% of that cabling isn't necessary if I'd just ditch the interconnects. Maybe I will, after I'm confident everything is actually working well.

DSC01812A.jpg


Regarding casing (which I assume is same as body) -- below is roughly what I have in mind. I enlarged the stock lower body to 44 mm depth, but I think I can reduce that a few mm (the stock one is about 22mm). The upper-body shown below looks rough because I cut it manually from another reference print, but it's basically what I'll end up with. I may be able to move the X8R receiver to the inside -- or I should migrate over to using the X4R instead. It's not real sleek, but I'm going more for a dump truck here than a racer...

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The video looks fairly good. If your controller supports it be sure to lower the rates. This will get you more comfortable with constant correction rather than a bunch of choppy corrections. Most new fliers do the choppy corrections. Lowering the amount of stick input you have will help prevent over correction and get you more comfortable.

If you have a soldering iron, you can do a lot of 'optimization' to that bundle of wires up top :P I'd wait until a few more flights though as it isn't an immediate concern, and it can get easy to be burned out with all the preflight work that this hobby has.
 
Agree looks like pretty regularly footage for anyone new. Getting used to throttle control and smooth deliberate stick input takes some time and good to be out in an open field where you don't need to worry about obstacles at first. Also agree you can reduce your rates or increase the super rate to reduce the reaction to small input changes. Looks like you're using self levelling as well which is I think pretty normal for new pilots too but you get smoother looking flight with acro mode since the quad isn't constant correcting itself back to level and fighting you. The wobbles when going through your prop wash are pretty regular but if it gets out of control with wobbles then need to adjust the PIDs but would check out rates first since they have larger effect on response to stick input.

Printed frame and all look nice and good to keep connections modular at first.
 
Thanks for all the suggestions! Throttle rates, and self-leveling settings -- and double checking the prop adapter bore. Will do!


Nothing too new to report for today -- I was able to re-print the lower body using 34mm depth instead of 44mm. And I added a "catch" to the side of the upper body, so the video TX ANT can't fall all the way forward (as it did in the video). The GPS+Mag is a bit more secured -- I noticed in the video the calibration was good at the beginning (0 was north, 90 was east), but then it seemed to have drifted about 20deg off after a few minutes later (south wasn't 180 and turn back north was no longer 0).


I can solder -- I did surface mount work back in college. A few parts are soldered (like the XT60 power connectors, and the red power switch on the back -- which can be by-passed). I can also use the soldering iron to just melt the printed body and do slight adjustments or repairs (like minor cracks). The print shown here is ABS (I just had extra rolls of "Clear"), but I have another print standing by in PLA for the next build. But yea, my initial goal was a set of "plug and play" components to avoid any soldering (I don't have great ventilation) -- that may have worked in the "250" size class (more off the shelf parts seem available there), but seemed a little harder to do in the larger 450/550 size.


If this survives the 2nd Flight, I'll probably have to come up with a name :)




DSC01833A_reduced.jpg
 
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We've started assembly of a second T4 (red/black)! Its First Flight went great.

It is using the same motors and ESC's (as our first T4, white) but the main difference is using a MicroVector FC instead of the regular full size Vector. Also using the smaller FrSky X4R-SB (still S.BUS -- found there is an even smaller FrSky receiver, but the X4R-SB paired up and works great).

We did better at packing the ESC's and were able to use the original T4 lower body cover (which is about 14mm depth). I cut all the internal XT60 connectors and used these terminal connectors instead:
TOOGOO(R) 50pcs Terminal(25 Female & 25 Male)Fully Insulated Wire Terminals Nylon Spade Connectors Set 22-18awg Nylon Fully-Insulated Quick Disconnects Wiring Spade Wire Crimp Terminal Red
(still not ideal, but they do work)


Happy to report these same ESC's also work with the MicroVector (all four are the same, UBEC). But the wiring for the MicroVector was a little trickier -- I went ahead and stuck with the Vector PSU and found there is a "MicroVector to Vector PSU Cable" available for a couple bucks.


I completed a 10 minute test flight. This 2nd T4 is using the original T4-designed arms (everything printed in PLA instead of ABS), and I didn't notice any particularly excessive heat from the motors (mild warm, certainly not hot). In 2D+Hold mode, I had some oscillation when changing altitude (up/down). But ironically (to me), when changing to 2D+NoHold, it was incredibly stable.

So stable, I could take my eyes off the drone now and then, and trust its position. I even took my hands off the controller once, and it just hovered there while I examined the belly (I was trying to see if the ESCs were getting too warm to cause any weakness or damage to the belly-- none noticed).

The pivots/rotations were nice too - I could trust it to turn left/right and not get uncomfortable.




I'll clean up the ESC signal wires a bit at the top, and add another video transmitter and camera. Then I'll go back to the original T4 and clean up its ESC wiring, now that I'm more confident about that.



My daughter still practices with the Syma X20 -- best drone under $20 IMO :)



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Had a successful 2nd flight, with more room to work with at a farm. It was fairly windy, but we managed a reasonable ranged flight. I didn't precisely time flights, but it was roughly 10 minutes each on 3 different batteries.


Main things I learned:

- my battery alarm is crap; I ended up falling out of the sky twice because of low battery (this configuration has no telemetry, so I have no idea how low the voltage really went -- got too pre-occupied to check the cells after each flight) [ obviously I need to work on the lower voltage fail safes ]

- the leg stands I guess did their job in absorbing most of the impact (they were all ruined); I don't notice any small cracks on the arms or body (both drops were in grass and about 10 ft up), it definitely still gets airborne just fine

- carbon fiber props are awesome, they held up very well after both drops (where the drone ended up flipped over)


VTx components are on the way, which will add some weight to the front to help balance it out better. Larger legs have been printed (like the first drone), so all that's left is to print the top cover!


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I've tried 3d printed landing gear as well unless they are very short they are likely to break from the force of landing. Any sort of off axis from center of the landing gear and it's putting bending force across the part so with long landing gear very likely to crack them eventually. I'm just using some pads on the arms of mine to keep the frame up off the ground and keep props from banging if I tilt a bit during take off but think some sort of take off pad and landing pad are really the best options, then no need to worry about the "landing gear" during flight.
 
Ah, maybe the short legs I had should have gone towards the end of the arm, not towards the body. In any case, replacing those short legs means removing the arm, which means removing the bottom to unhook the wires to the motor to get the loop inserted. So now I'm a big fan of externally attached arms or skids!


We got more flight time today, nice 85degF but still a bit windy. I can confirm that the flight times are at least 9 minutes. The Blue/White (Ice) configuration has the video transmitter, so it was closer to the 9 minute span. The Red/Black (Fire) configuration (or my daughter calls it the LadyBug) was closer to 12 minutes. As far as low battery -- I need about 3.6 per cell, or no lower than about 10.8V. I have a better battery alarm with a more adjustable set threshold, so that's dialed in now.


I had a hard tumble with Ice when switching to "3D+HdgHld" mode -- it literally dove forward and just tumbled maybe 30ft. The support to hold the battery secure peg broke, and also one of the legs got 3 major cracks. It can still stand and fly, so I'm lucky that was the worst of it.

These C-legs I'm using are fairly straightforward -- and as shown, they can "pivot" around the leg. So basically in storage/transport configuration, I keep them "straight" or "down" (easier to hold in a box). But for take-off, I angle them, and they have a nice set of "bounce" in them to absorb impacts. I flew 3 batteries on Fire/LadyBug -- there were some hard landings that twisted these C-legs, but never really broke them entirely.

These legs are easy to print (maybe an hour), but because of their size, I can only print one at a time. The one that got damaged below I think was 20% ABS, while the black ones are 40% infill of PLA.


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Idle/Storage/Transport Mode legs (straight down) vs Flight/Ready/Pounce/Aggressive Mode legs (angled).
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Other notes: I found the Vecctor Advanced controls for PIDs, response percentages, and a Gain control. One thing I've learned is I shouldn't do a full tilt forward then a full tilt reverse -- that made it very unstable and nearly lost control. So I have to very gentle on the controls, very slow movements. Lots of dials to play with!
 
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Yah those curved ones look pretty solid, if you end up needing to reprint a lot of the same part probably worth making a silicone mold and then pouring resin to get a solid plastic part, they end up a lot stronger and can play with different resins (smoothon is a mfg with lots of info on how to do it). I replaced probably 10 arms on my 3d printed one then bought a plastic frame and that lasted about 2 yrs and recently broke it so upgraded to a CF frame.
 
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^^ can see my new setup here... I actually moved the arms down outside the body cause the boards were really crammed in there, it's all a tight fit but pretty fun little cruiser. I'd like to build a big one like yours as well for the longer flight time and to play around with ardu-pilot can you give me a rough idea on price for components for one of those?
 
Nice idea on the silicone molding, maybe another chemistry-related project my daughter might be interested in!


Brendan22, the guy who made the T4 design I started with -- he lived near where the Shire was filmed (LOTR), so lots of land to play with there. He made a 450/315/250 class designs, and some 8-motor, 6-motor also. Cool stuff from the 2014/2015 era :)

I tried finding the Q-Brain that he mentioned for the ESCs. I didn't search super hard, but it seemed unavailable at a lot of vendors anymore (it may have had some heating issues). So cramming the full-size ESCs has been a hassle, in terms of some custom splicing or soldering work... But when printing your own, you can just stretch the height of the original design so all the screw holes still align (if you need larger payload space, but it should be because of an actual payload need, not just because of lazy wiring that I'm guilty of).

DSC02078A.jpg
ABOVE: Getting the ESC's all flat instead of stacked is possible -- a better way is to just direct wire the ESC/motor connectors, and group up the power connectors. Of course, even better is something like a Q-Brain, but I couldn't find one -- and so couldn't verify if it works with the Vector FC.



Today's flight was fun, since I felt like I was actually flying the drone, doing what I wanted to do (i.e. make it go where I wanted to go). But had to be pretty delicate on the controls, with constant thrust adjustment to compensate against the wind.


Now-a-days, yes, I see a bunch of stuff in the sub-"250" class drones in the $180-$250 range (without GPS, and without a transmitter/receiver). Like I'm trying a Vortex 180 and the Babyhawk-R, to get myself more familiar with that class.

Your drone looks awesome, CF definitely seems to be the way to go! The larger "450" class has been fun, I think it's been an easier way to show my daughter how the parts work together -- the anatomy of a drone -- it's all the same concepts as a mini-drone, just scale larger (and supports correspondingly larger range). Brendan22's videos on Thingiverse show that best.

Going from like 5" props to 10" props, or 250 to 450... IDK, I'm not expert there. What's funny to me is it seems the cost is basically $1 per class-size (for the base parts). Like the 250-class is roughly $250, and the 450-class is roughly $450 -- by base parts, I mean motors, FC/ESC, body, RX, battery, videoTX. The other parts, like TX and VideoRX, can (typically) be re-used across both classes. That puts the 450-class at 1.8X the cost of 250, so not quite double. [ and smaller parts, like 136mm-180mm platforms, are under $200 for the base components -- but that seems to be the case for 2018, it wasn't like this a year ago, AFAIK ] To all of these prices, of course then add maybe $400 (retail, higher end components) for signal TX+RX, VideoRX (LCD or head mount), GPS.
 
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Nice idea on the silicone molding, maybe another chemistry-related project my daughter might be interested in!


Brendan22, the guy who made the T4 design I started with -- he lived near where the Shire was filmed (LOTR), so lots of land to play with there. He made a 450/315/250 class designs, and some 8-motor, 6-motor also. Cool stuff from the 2014/2015 era :)

I tried finding the Q-Brain that he mentioned for the ESCs. I didn't search super hard, but it seemed unavailable at a lot of vendors anymore (it may have had some heating issues). So cramming the full-size ESCs has been a hassle, in terms of some custom splicing or soldering work... But when printing your own, you can just stretch the height of the original design so all the screw holes still align (if you need larger payload space, but it should be because of an actual payload need, not just because of lazy wiring that I'm guilty of).

View attachment 4503
ABOVE: Getting the ESC's all flat instead of stacked is possible -- a better way is to just direct wire the ESC/motor connectors, and group up the power connectors. Of course, even better is something like a Q-Brain, but I couldn't find one -- and so couldn't verify if it works with the Vector FC.



Today's flight was fun, since I felt like I was actually flying the drone, doing what I wanted to do (i.e. make it go where I wanted to go) rather than just staying in the air. But had to be pretty delicate on the controls, with constant thrust adjustment to compensate against the wind.


Now-a-days, yes, I see a bunch of stuff in the sub-"250" class drones in the $180-$250 range (without GPS, and without a transmitter/receiver). Like I'm trying a Vortex 180 and the Babyhawk-R, to get myself more familiar with that class.

Your drone looks awesome, CF definitely seems to be the way to go! The larger "450" class has been fun, I think it's been an easier way to show my daughter how the parts work together -- the anatomy of a drone -- it's all the same concepts as a mini-drone, just scale larger (and supports correspondingly larger range). Brendan22's videos on Thingiverse show that best.

Going from like 5" props to 10" props, or 250 to 450... IDK, I'm not expert there. What's funny to me is it seems the cost is basically $1 per class-size (for the base parts). Like the 250-class is roughly $250, and the 450-class is roughly $450 -- by base parts, I mean motors, FC/ESC, body, RX, battery, videoTX. The other parts, like TX and VideoRX, can (typically) be re-used across both classes. That puts the 450-class at 1.8X the cost of 250, so not quite double. [ and smaller parts, like 136mm-180mm platforms, are under $200 for the base components -- but that seems to be the case for 2018, it wasn't like this a year ago, AFAIK ] To all of these prices, of course then add maybe $400 (retail, higher end components) for signal TX+RX, VideoRX (LCD or head mount), GPS.


When you get s chance I'd shorten the wire now that you know the build will work and then remove those crimp connectors. You can grab a 12$ weller soldering iron, some 60/40 and flux. The problem with these is that the current going through them can cause them to corrode and they might even break connection mid flight causing a crash. Even if they are rated for such current you can have a small skin effect (the current only uses the outer skin of the conductor at high frequency) problem with AC.

Either way it is a great build, and I would love to see some video!
 
Yeah, half thru re-wiring the Red/Black drone I realized that I should have stuck with the bullet connectors. I ended up doing that for the Blue/White one, as shown below. Still not optimal, but it does allow that drone to also use the original sized bottom tray. Also at the bottom of the body, I use a soldering iron to just re-melt some past excess PLA and fix the battery tie-down that had busted off.

DSC02120A.jpg
 
Aside from MicroVector versus Vector FC, these are two very similar builds (still just one GPS to share between them, but same ESC/motors and VideoTX/camera). Waiting for some more CF props, and still playing with PIDs and many other Vector configuration dials. I've flown both and they work, but I still have to manually oscillate the throttle to hold altitude (so still working on that, working with Gains on a dial).

And the weight numbers are in!

white/blue 1279g (no-batt) 1703.2g (w/ 3S) (423.9g) (ABS print, probably 20% infill)
red/black 1357g (no-batt) 1845.6g (w/ 3S) (486.6g) (PLA print, probably 40% infill; not sure the mah but it's a slightly thicker 3S battery)

So, certainly no suave Mavic :) Brendan's original notes were 1100g weight without battery, so I think I'm on par with that (he didn't fly with a top cover or landing gears, plus my excessive ESCs+wiring -- that all accounts for the extra ~180g -- but he did fly with more serious camera, which wasn't included in his weight -- he said another +1000g for camera gear and battery ).


Wish I could have found some more efficient motors in this size (roughly 28mm x 28mm) -- and in different colors haha! But at least they fly and are good practice drones.


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Here is a closer look at how the up-top wiring ended up between the Vector and MicroVector, which could still also be cleaned up a bit further. The Vector does have the extra capability of supporting stereo audio relay thru the VideoTX, which I haven't tried yet. I didn't see any Audio support or wiring in the MicroVector. Not a huge deal, since I assume all you're going to hear is the motors. Still, I stuck with the same VideoTX and camera between them, just for consistency. I may try the Audio thing eventually, but first I want to figure out a remote-release drop (especially since they can fit the shallow lower body now).

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Gotta be careful with PLA. Before I knew just how heat resistant it was, I had printed some frame parts for a quadcopter as it felt stiffer than some ABS parts. Got in the hot car and drove over to the field to test and the parts were floppy like wet noodles. Just from the hot car hahahaha Lesson learned the hard-ish way :P

The bullet connectors are ok, they weigh a little more but also make for in-field swapping of ESCs and stuff really easy if you accumulate spares. While they do offer another thing to go wrong, I think it is a small enough chance that adding them to the pre-flight check should be all you need to do.

They are looking great, when they are all together it is looking like a really clean build. How do you like this design for landing gear? Do they feel smooth on landing or do they want to catch?
 
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