Under 250, Under 250, Under 250!!!

[Craftydan]

Dan, mind if I try out your cleanflight PIDs? I for the life of me cannot get this thing to land with it violently bouncing and flipping. I'm though a dozen props and i haven't really even flown it yet! Having trouble getting air mode to actually shut off, regardless of my switch settings and think i'll just run cleanflight if it's working well for you!

I can't get to the actual numbers until I get home, but mine flew fairly well on the Mulltiwii rewrite's stock with the 3S 850mAh. D was just a touch low and I was quite a bit high, but it flew well.

On the 2S1000 or 3S1300 (~275g AUW) it still flew fine, but P could go up quite a bit (almost a full point, IIRC), where I and D was roughly the same.

Change the AUW and/or voltage, the ideal PIDs move as well.

 

[AdamV]

Thanks! Good enough starting! I'm running 850 3s as well

 

[trevoof]

Craftydan, thank you so much for this wonderful thread, I learnt a lot from it. Will you re-post this as an article? Saves lazy readers (like me) a little bit of time hopping back and forth between the pages to find relevant information.

 

[Craftydan]

Probably not. Each of the update posts is practically the length of an article in itself. A quick glance back and I count 10 article's worth, easy . . . and I haven't finished yet, I just stopped writing I still need to hit the FPV setup (OSD was abandoned -- I got it to work, but not reliably enough I felt good about selling it), basic tuning, and summary.

All told that's a 13 part article series . . . and while I enjoy the time I get to fly this guy, I'm kinda ready to move on to other builds. In the past week I've been "taking a breather" and "catching up" on projects . . . rebuilding a DLG tail, refitting and cleaning up a Flyzone tidewater I picked up for a song, repairing a balsa wing that had a tree-limb-sized chunk missing from the LE, sorting out camping gear, cleaning out a very nasty green pool, and helping my wife buy a violin . . . you know, taking it easy On the "very soon" build list I've got at least one (if not two) foamboard builds I'd like to slap together, a balsa glider I've been planning to build out for months, a new 3m glider kit mocking me and my building skills, and an 80% complete project that might *actually* make money that I've been procrastinating on . . .

That's all to say, I'm going to have to force myself to finish this thread here. re-encapsulating this into an article . . . that's optimistic.

 

[trevoof]

That's very understandable, all the information is here anyway. Thanks again for this awesome thread! Looking forward to reading about the rest of this build and all the fantastic projects you have lined up.

 

[thenated0g]

Nice little quad. Here is another flitetest fan's build of a 150g multirotor:
https://www.youtube.com/playlist?list=PLPlPgQFfbIvGyiOu4no0WXpCu2FR7ZooE

Also he just made this video that shows you how to mod your mobius and get it down to 20g:
https://www.youtube.com/watch?v=XtqgCfgjb14

 

[humphrey111]

All finished! Oddly, the camera gave me fits, until i stumble on post with similar problems which were solved by disconnecting the audio wire. Well, that fixed my issue! It's not super pretty or incredible well organized, but it all fit in there. Should get a real maiden in soon.
View attachment 65193
Used your camera mounting technique

View attachment 65192
Hoping my battery/antenna doesn't mess up my satellite reception

How has the battery on top worked out for you? I am building one of these as well and I just don't see a good way to route the battery cable down to the pdb to keep it from getting hit by the props.

I added height to get everything inside the top and bottom plates but I think I'm going to have to mount the battery on the bottom anyway.

 

[AdamV]

i zip tied the battery cables near the back juuuust out of the way of the prop. It seems to work fine as far as that goes. The batter on top seems to be fine, but i can't tell you anything as far as flight characteristics because i'm having some issues with min throttle and haven't gotten any real flying.

 

[humphrey111]

I'll probably just keep the battery on the bottom. The cable that close to the props makes me nervous.

I'm still working on my build, i don't have a lot of time to devote to it. I'll post up pics when it's finished.

 

[thenated0g]

Enjoyed your thread. Very nice build. Just wanted to share my 155g build. About 220g AUW with Graphene 800mah 3s 45c pack. Thing is a rocket ship. I think about 4:1 power.
20a esc, 1306 4000kv motors, diatone pdb v5, 3" triblade props, naze32, quanum 200mw (removed sma and direct soldered antenna), x4r-sb (no pins), Same camera you used, buzzer alarm, and a fbvs-01 voltage divider.

 

[AdamV]

Dan, you tried it on 3s yet?

I don't have 2s small enough for this, so have only flown it with 3s and it's waaaaay too fast for my backyard. If the wind in vegas, ever dies down i'm hoping to take it out and let her rip. I have a buzzer for it, but haven't installed it, i haven't decided how i want to setup my DX6 for it since i'm limited on channels

 

[Craftydan]

It is pretty zippy.

Yeah, mostly been flying on 3S . . . usually on the 850's but in a pinch I drag out my 1300's. Flying it with the heavier 3S 1300 (or 2S 1000) will mellow her out a bit, but in a tight space on LOS she will always feel "caged" . . . which is complicated by the fact she's hard to maintain orientation as she picks up distance.

FPV -- so long as you've got the room -- is not as bad.

I can see in a small back-yard being stuck with the NASCAR track -- lots of left turns and you don't quite have the room to open her up before you hit the wall on the next turn. I am fortunate that I've got a side-lot at my house with some 5-10'-ish canopy trees. Not quite enough room to practice freestyle aerobatics, but generally I don't have trouble staying under the branches . . . so long as the leaves are still on them :black_eyed:

 

[trevoof]

Finally got round to building a version of an under 250 quad. I think it's gotten a bit easier since Craftydan started the post, mainly because lightweight combined vtx and camera units are available at a reasonable price.

Anyway, here's my specs:
Diatone frame $20
Naze rev 6 acro $25
XSR FRSKY rx $27
Quanum elite micro vtx+camera $38
RCX 1407 motors $48
DYS 16A ESC $51
Turnigy 800mAh 3S 20C $8 (C rating too low, but that's what I have around, probably upgrade to 25/40C nanotech $8 about the same price)

AUW is 207g.

Total cost of main components $217. The remaining $30 should be enough for props, wires, connectors and other accessories.

Flies reasonably well, perhaps a bit of drift, bit more tuning required. 2S feels very underpowered for me, and my 800mAh 2s 20C can't seem to support the current draw anyway. Flight time with 3S battery is about 3 mins before voltage consistently dips below 10.7. Perhaps a higher C rating battery might help. Also going to try it with a 1000 mAh since I still have some weight to spare.

I mounted the Naze without any offset angle, and only realized one of the pillars gets in the way of the USB connector. So need to remove that pillar every time I do any adjustments to the FC.

Haven't got round to making Craftydan's E-motor wrench, hence just have regular conical prop nuts on at the moment - hope the props won't fly off during testing!

Not a fan of the bullnose props, going to look for some 3 blade props.

Overall it's a really fun build, loved the challenge of packing everything neatly into a small space.

Thanks for the inspiration Craftydan.

 

[Craftydan]

Congrats on the build trevoof!

Yeah, the TX/RX combos do simplify things, but every one I've seen is low power and RHCP. They also won't support OSD, not that my final version had one (I did get the minimOSD to work, but power issues were a constant struggle, and not worth the trouble). None of those problems are no-go problems, but the do limit what the can do. Typical trade-off between convience and capability.

If those are 4" props, I suspect your "underpowered" feel is sag from the low c rating. I'm running a slightly higher auw with a 2s 1000, but they're 40c packs. With that I have well over 3:1 (not the punch you get with 5:1, but still fast and turns on a dime) all on standard 4x4.5's. My WOT is just shy of 40A, which would make a 20c 800 suffer. If that's the case, unless you're running 3" props, beefing up the prop will only make the problem worse, since the motors already can't take advantage of the props you have.

 

[trevoof]

Thanks for the tips Craftydan.

They are 3" props. The spec suggests up to 3.5" but there doesn't seem to be enough clearance for anything larger than 3". On hindsight, I would have picked a different frame that supports 4" to get the most out of the motors.

But I do take your point that the battery is probably my weakest link. My first thought is to put in an XT60 connector and go with the 1000/1300 batteries I normally use on the 200/250 quads (should just squeeze in under 250). Balancing becomes a bit of an issue though (very tail heavy), and it highlights one shortcoming of the the combined VTX/camera - there's a rigid CP antenna poking out the front that limits how far forward the battery can go and the vtx cannot be moved around to balance things.

Which brings me back to an important lesson you spoke of at the beginning of the thread... should have thought deeper in design stage and iterated earlier!

 

[humphrey111]

Posting here to see if there is any interest.

I starting building one of these, but I just don't have the time to finish it up.


It's basically all together. I haven't flown it yet because the ESC's that I thought were single wire programmable, are not. So I was unable to reverse motor direction on 2 of them like I thought I could. All mototrs currently spin the same way, so 2 need desoldered and reversed. Parts list below
Diatone grasshopper 160 frame
1407 RCX motors
20A buzzer BLHeli esc's
diatone naze 32 FC
Tiny DIY Frsky receiver from Banggood
RCX TS5823 5.8GHz transmitter w/antenna
Aomway HD Mini 1/3'' CMOS 600TVL 2.8mm FPV Camera
WS2812B LED And 5V Active Buzzer
Will include a few sets of bullnose 4" props and a few sets of regualr 4" props
NO battery included

I'd rather just sell it as is, but I might part it out. $150 shipped to US.

 

[trevoof]

Made some mods with these objectives in mind:

• Better balance
• Longer battery life
• More power

Modifications:

• Extended the camera to sit in front of the frame - so that I can push the battery further forward for better balance. The antenna used to limit how far forward the battery can sit. Unfortunately this means the camera is now horribly exposed - probably the first thing to wreck in a head on crash.
• XT60 connectors instead of JST such that it can now use 1300mAh 25C batteries from the miniquads. Get about 6 mins of flight without unmanageable dip in voltage.
• 3040 tri-blade RotorX props - didn't notice a significant increase in power compared to the 3x3 bullnose. I guess the bullnoses do have quite large chords that helps it bite.

I do love the way it handles, it somehow feels more precise compared to the regular miniquads I have, much in the same way miniquads feel more precise than my regular sized tricopter. I suspect the small size and high disc loading also makes it less susceptible to the wind.

AUW after modifications... just in at 248.5g.