EMAX 250 Pro FPV mini build (with Naze32 GPS experiments)

[jhitesma]

Oh - and that doesn't mean I won't be experimenting with Pos Hold and RTH. Just that my expectations for them are pretty low due to my experience with them on MW. But I do enjoy a challenge and tinkering and surprising myself is always a happy thing I just want to make sure no one is waiting for me to walk on water or anything!

 

[jhitesma]

Working on mounting up some motors and found that I need to ammend my second post. These motors actually include 3 sets of mounting screws not 2. 8mm, 6mm, and 4mm. I'm going to use the 6mm since my arms are just a hair over 4mm, that should give them enough to hold onto the motors well without getting too close to the stators. The metal on the bottom of the motors is 4mm thick so the 8mm screws probably wouldn't protrude, but the 6mm seem to have enough grab that I'm not going to risk it. If the arms were a full 5mm thick I'd go with the 8mm screws but since my arms measure closer to 4mm I'm going to go with the 6mm screws.

Also I made my little video exploring the properties of this hybrid frame material:

If you can't or won't watch the video...I used my ohm meter to check the conductivity of the G10/CF material. I confirmed that the center material does seem to be G10 as it's non-conductive and the outer layer does seem to be CF as it is conductive...but it also seems to be VERY thin so I'm thinking it's mostly for looks, but might contribute a bit of additional stiffness since it is laminated to the G10.

 

[jhitesma]

So, back to building! I didn't have a whole lot of time today to work on the quad. And Twitchity made great progress on the files for the PDB v2 on his quad so I had to spend a bit of time on that (No, sorry everyone nothing to share on that just yet!) But I did get my "mockup build" more or less completed and have a gameplan mostly together for how I hope to start on real assembly tomorrow.

As I was about to walk out the door for lunch with my wife my mother called to talk to her - so while they chatted for a minute I went ahead and test fit the Naze32 and afro power board. I may hit the hardware store tomorrow though to see if I can find some slightly shorter standoffs for the Naze. The ones MRM provided are nice if you're going with pin headers but I'm going to skip pins and direct wire just about everything as I've already mentioned and I'd like to run the board a little closer to the lower plate to leave more room for my OSD and VTX above it. I'm also still debating just which RX I'm going to use. I have on hand my openLRS which I'd like to use but I'm not sure I trust anymore, parts to build a DIY openLRS, a homebrewed FlySky PPM RX that works but needs a bit more cleanup and packaging before I could fly with it, a couple of Lemon 6ch DSM RX's but they're not PPM or UART, and an 8ch Lemon with failsafe and UART. I thought about picking up a lemon sat but I think I'd rather go with a fullsize RX on this. And I'm pretty sure I'd rather go with PPM over UART since UART ties up a serial port on the Naze which will make running GPS and OSD more difficult.

I'm probably going to try my openLRS first as I'd love to have the setup I used on my knuckle with PPM for control and full telemetry. If it doesn't work then I may try and wire up my own openLRS RX but will probably end up tossing on the 8ch Lemon over UART instead just to get in the air quicker.

Point I was going to make is whichever RX I go with I'm not planning on mounting it under the Naze on this build. Also the Afro power board has positive on one side and negative on the other - since CF is conductive (see my video above) I don't want to mount it flush against the frame. I plan on mounting the naze with the 8 provided o-rings sandwiching it but for now I just used 4 and used the other 4 to space the afro off the frame a bit:


I'm not happy with this though, I want the Naze closer to the main plate and the afro further from it. I may try cutting the provided spacers in half then cutting the heads off some nylon screws so I can use half sized spacers on top and bottom. I'll probably hit the hardware store tomorrow morning to see if I can find some m3 spacers and do a few experiments. Or I may just cut some bits of fuel tubing and use them as spacers between the afro and the main plate:



Didn't get to make any more progress until this evening when I started test mounting the motors. I got all four on and then proceeded to play with the ESC's...think I'm going to go with Mustangs suggestion and put them between the main plate and the bottom plate with the afro board. I'm a little worried about whether they'll get enough airflow there or not...but I like the clean look and the wires are long enough even without the bullets so I think I'll give it a try. Mounting them on the arms would require adding longer power wires and that's a bit more hassle than I want to mess with right now.

Once I had the motors on I tossed on some props to get a good feel for how it's going look once it's all together. Then I piled on a few more bits to get a rough idea what it will weigh on it's maiden flight without GPS, OSD, and FPV gear installed yet. I tossed one of the 6ch lemon's on there as a sample RX because it was handy. About 323g...not bad at all, should be a full little flyer at that weight!

BTW - Any of you guys who've used these motors before care to take a peek and confirm I've got them in the right position with the CW/CCW threads...think I got it but I keep getting mixed up:



Since I had the scale out I figured I may as well take a few more weight measurements out of curiosity and start seeing how all the gear I plan on packing into this bad boy will fit.

The bullets I'm not going to use will save me all of 7g:


The GPS I plan to use comes in at 17g:


My FPV gear weighs in at 72g though I'll be loosing a few grams of wire and will probably ditch the pins on the minim to save another 1-2g:


All together it looks like about 130g of payload between the FPV gear, the Mobius and the GPS:


So fully loaded I'll be looking at more like 452g in the air:


Oh wait...need a battery too, a 1.3 nanotech brings us up to 547g expected weight fully loaded:



So based on Mustangs tests of these motors it should pretty peppy on it's maiden with more than 4:1 power to weight. But once I load it down and have it fully prepped for FPV with GPS and OSD I'm looking at a bit closer to 3:1 - still respectable and fun but not an all out screamer. Of course I could always upgrade to some 24mm motors once I get used to it if I feel I need more power

Tomorrow I'll do a few tests with my openLRS and decide if I'm going to use it or not. Then I'll tear this down to bare plates, give them a bit of attention with some sandpaper to smooth out the edges...and fire up the soldering iron! With a bit of luck I may have it ready for a LOS maiden flight by Sunday morning.

But for now my wife just came home so I'm going to eat dinner and get some sleep. I've got an FT-22 to maiden in the morning

 

[x0054]

BTW - Any of you guys who've used these motors before care to take a peek and confirm I've got them in the right position with the CW/CCW threads...think I got it but I keep getting mixed up:

The way I double check is by placing the cone over the shaft and spinning the motor in the intended rotational direction. If the cone tightens, you are all good. Basically, you want the cone to tighten in the opposite direction of the motor rotation. So, if you intend the motor to spin CW, you want the thread to tighten CCW, and vise versa. You blades look right, but I don't remember the cap colors.

Also, I never tried it my self, but CleanFlight claims to support serial rx over soft serial at up to 19600 baud. They don't recommend to run GPS over soft serial because apparently you can't get a fast enough GPS refresh rate over soft serial. Just something I read.

 

[cranialrectosis]

"My main interest in GPS is still for feeding the OSD. Being able to tell which direction is home is more useful to me than trying to have the quad fly home."

Yes!!!!

As you wire this up I will be following intently.

 

[jhitesma]

Woke up this morning to 20-30mph gusts. So much for my FT-22 maiden.

Instead I pulled out the loaner flip pro I have sitting here and configured it for PPM, then hooked up my openLRS rx....and it worked beautifully. So apparently the problem is with my mega board on my knuckle and not with the openLRS itself. Not sure why I keep having PPM stop working on my mega boards but that's a problem for another day now. This solves my RX question, I'm going to go ahead and run the openLRS on this build since it gives me the most options and I really loved having FULL telemetry. Though that may make things a bit complex as the Naze32 by default doesn't have enough serial ports to run telemetry, OSD, and GPS so I'll have to dive into soft serial if I want to run all of them. At first I'll just run telemetry and not worry about OSD...I'll add OSD in later when I add the FPV gear and will probably disconnect telemetry when I hook the OSD up. Then once day when I'm feeling adventurous I'll dig into soft serial and see if I can't get OSD and Telemetry working at the same time.

Note here though...the way I run telemetry is different from how it's normally done. This isn't telemetry through my TX it's just using my TX's RF system as a transport. I haven't modded my 9x for telemetry and really I don't have much interest in that as I don't want to look down at my TX or listen for beeps from it. Instead I use the openLRS "passthrough" telemetry to pass the serial stream from the FC down to a bluetooth module and then use my phone to view the telemetry. So my RF system just acts like a long cable connecting the serial in/out on the FC to the bluetooth module which is hooked to my TX module instead of right to the FC. I like this since it lets me use the MW EZ-GUI as a ground station and view my position on a map, and basically have all the goodies of the baseflight/MW config programs right there on my phone. Makes tweaking PID's super easy, allows me to log flights, and let my phone announce things like when I change flight modes or my battery hits the level I setup.

So...with those decisions made I'm going to go tear down the quad and start finishing the plates so I can dig in on full assembly later today. I may take a quick break though to pop this Flip Pro onto the twitchity quad....too windy to fly it today but I'd like to get that done to see if the afromini is the cause of the issues I've been having on there. With someone else having the same problems I'm having with the same board but almost nothing else in common between our quads...I'm really starting to suspect it could be the mini causing those issues.

 

[Tritium]

Prop nuts thread opposite rotation direction confirmed! My Grandad had a 62 Rambler (which I still have) and the passenger side wheels had left handed lug nuts so I always remembered that little tidbit.

Thurmond

 

[jhitesma]

Haven't got much more done. Daughter didn't nap today so she was cranky and exhausting to be with - and I didn't get any more hobby time. But it also means she went to bed right on time and fell asleep quickly. I did get the frame disassembled this afternoon and made a first pass with 230 grit wet dry sand paper under water. It's a lot better - but it's a LOT more work than the G10 twitchity frames which I did with 400 grit in just a few minutes. The carbon outer layer is a lot harder and the design of this frame and project means there's a lot more parts and a lot more internal cut outs that need to be smoothed where wires will pass.

About to dig in on the second round. So far today's hobby work as been drudgery. Removing pins from a FC and finishing CF. But once I finish this the real fun of assembly may start to night and it won't take too long to get it ready for a maiden. Getting the FPV gear on this weekend isn't likely. I may start on the GPS...but I think I want to do the FPV gear first. And I want to cleanup the wiring on that a lot when I do it. I'm going to bite the bullet and just do a permanent install instead of continuing to try and keep my FPV gear modular enough to swap from vehicle to vehicle. On something this small I want to avoid any excess wiring and connectors for space and weight, and it's just too fiddly to be adding and removing gear all the time. I also don't really plan to fly this without FPV gear once it's installed so it may as well be a dedicated install.

Which means I'll have to start shopping for a new TX and cam for my versa...gives me an excuse to try out some 1.2/1.3 gear like I've been wanting to Not that I need to pile on another project. Twitchity is already better at diptrace than me it looks like so that will probably help shorten my project list a bit

Ok...I'm just stalling on this sanding now...

 

[jhitesma]

Yeah...that sucked as much as the first half:

But the frame feels MUCH nicer now. Doesn't cut my fingers up and make them itch anymore either. May still have to do a bit more touch up with some finer sandpaper (I only had 400 grit) where wires will pass...but it's just so much nicer to work with these pieces now.

Was going to start assembly....but about out of time and the light will be better tomorrow to time lapse it. May do a bit more work on de-pinning the flip but it's about time for dinner and bed.

 

[cranialrectosis]

Is it just me or does this video not work?

 

[Cyberdactyl]

Works for me.

Jihitesma cleaning the edges of carbon fiber parts in fast motion with a file over running water in a sink.

 

[Twitchity]

Must be you, video works fine for me. He does sure sand fast.

 

[jhitesma]

Didn't set any restrictions or anything...must be a youtube hiccup.

FWIW, the scars on my left hand are from filming my friends maiden of his warp with KISS esc's:

Which is why in the next few videos of him flying at the field I was nervous and kept telling him to get more distance between us and the warp

Swapped the flip onto the twitchity last night...but it's not happy. For some reason I can't get 2.3 to flash on the flip pro so I went with the RTFQ default 2.2 distro...but it's acting goofy...motors won't spin until almost half throttle no matter what I change the minthrottle to even after I recalibrated the ESC's. And even after checking the wiring 4 times against the wiring diagram from RTFQ once the motors do spin up it wants to insta-flip as if the motors aren't wired correctly. Will probably try to get 2.3 on it again later this afternoon. But for now I'm itching to make some progress on this build instead. I just feel cursed on the twitchity hardware right now and feel like I need another successful build to shake it off before I can come back at it with a clear head

Got my bench cleaned off and parts laid out and mobius setup to time lapse it...should be starting the build shortly!

 

[Cyberdactyl]

Ooopps! Sorry to see that.

Yea, I had my slicing early on with soft slo-fly props, so I was lucky it wasn't carbon or glass props.

That's why I'm reluctant to launch and catch them. All it would take is a bump of the throttle and an awkward orientation. . .

 

[jhitesma]

I was just glad I had my hands in front of my face holding the camera. Scars on my hands I don't mind. On my face...that wouldn't have been so good. He just lost orientation and by the time he realized it couldn't save it or ditch it. Not much worse than a couple of paper cuts. I've got a far worse wound from a hot glue drip building the FT-22 last weekend. Had the gun plugged in longer than I realized and the glue was hotter than normal. Didn't notice it dripping and since I was holding parts in place couldn't easily wipe it off. Nasty little pea sized 2nd degree burn from that.

I've always practiced good prop safety, hand launching doesn't bother me much on a reliable setup - even hand launched a few iffy setups and have never had a problem. Hand landing - I'm a lot more cautious on. And have gotten nicked with that but knew the risk I was taking. So far my safety perseverance has paid off. I just think of a motor with a prop on it as a mix between a power tool and a weapon and treat it with the respect and attention required by either of those.

Back to the build...just stopped in to start a podcast in the background since the girls are out of the house

 

[Balu]

Damn. I ducked seeing that Warp flying towards the camera :-D

You are lucky that you just got some small scratches on the hand.

 

[Twitchity]

I did the same thing but to myself while learning how to fly a mini CP heli. This was the very first heli I tried to fly ever and I lost control and it came straight towards my face. Raised my hand up to stop it and the blades took a nice chunk out of one of my fingers. Could have been a lot worse, but still hurt like hell. Probably should have got stitches, but holding the wound shut, wrapping it with a paper towel and holding it together with scotch tape worked just fine

 

[jhitesma]

I'm used to shooting with a big SLR in front of my face. So when something comes towards me it's instinct to push the camera towards it and duck or jump away. But the mobius didn't work as well as a shield compared to the SLR's I'm used to

The build is going well. Just need to add a battery cable and it's ready for first power and testing that the RX works and that the motors all spin the right way. I'm REALLY happy with how clean the build is coming out. Taking my time and watching for a lot of little details I've skimped on in the past.

Build log to continue tonight but here's a sneak peek at the progress.

Bottom is very clean and wiring is still only temporary. Once I confirm all the motors are going the right way and working I'm going to add some sheathing or heat shrink to help protect against any chance of shorting against the frame in case my finishing job was lacking:


Mounted the OpenLRS on the back with some velcro. Just wired up for PPM right now. I will reflash the TX and RX both to the latest version of openLRSng after I confirm everything is working. This should fly on the same TX settings my knuckle does so TX setup should go quick.


No props battery cable or battery yet but still only 311g - not bad!


Bad news is the timelapse missed most of me working on the bottom I looked up and my camera had stopped. Reset it...kept working...and it stopped again. Did that a few more times before remembering it was set to not charge over USB since I was using my android as a preview screen - and apparently that was keeping it from charging off the charger it was plugged into. Changed that setting and it finally started playing nice, but had missed parts of the build I really wanted to capture

I got photos of most of the details though so I've got a lot of material for tonights post. Just need to to put power to the ESC's and do some final setup now!

 

[jhitesma]

Video uploading - but it's airborne...after 3 attempts



You would think that by now I have the experience to avoid breaking a prop before it's off the ground the first time. 2 rookie mistakes - one of which I had repeatedly warned myself not to make. I'll save the details for the video that will be up shortly.

Build time lapse (what I got of it) is uploading as well. Need to go do some shopping now then I want to enable telemetry so I can do some tuning - it's a bit shakey still (of course that's with a bent prop and gemfans I haven't balanced yet.) and on 100% default settings other than enabling PPM, enabling timeout and shortening the time the motors stay on (then testing that it works ), and rotating the board 90.

I do still need to calibrate the ESC's. I tried a few times but it didn't seem to take, and I have to raise the minthrottle a bit higher than I'd like to get them spinning on arm right now - 1170). It hovers around midstick but feels like the throttle curve is a bit off still. Very smooth in the air and both acro and horizon work (I didn't try angle yet, I almost never use it.) But it's very windy out and I didn't want to risk any accidents yet

The motors do have that same high pitch whine that Twitchity noted on his so I'm pretty sure it's the emax ESC's running a lower PWM rate.

If we get some calm air this evening I may toss some HQ props on it and hit the park for a pack just to have some fun with it before weighting it down with FPV gear.

Anyway the plan now is:

1) Telemetry
2) GPS
3) FPV with OSD

I may actually get most if not all of that installed and working today...but doubt it will be done in time to test fly with FPV...might get to test fly with GPS. Telemetry should be just adding two wires so it will only take a minute. The rest is all software on that. GPS is just 4 wires and some more complex software...and the tricky part for me - deciding where/how to mount it. I have a few ideas though. Testing will take more time on this and I plan on getting FPV up and going before I really dig in on trying different fimrwares and optimizing GPS performance.

Will share the videos later when they're done uploading!

 

[jhitesma]

Ok, finished before I walked out the door so here's the 3 part maiden