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Knockoff is the New Black

jhitesma

Some guy in the desert
Mentor
Oh...as for the TBS Gemini. Let's be realistic here. TBS is the marketing arm. They didn't develop the quad. I'm sure they're playing some roll in refining it for retail but their primary role here is salesman not designer/developer. Just like almost everything else they sell. They don't do much original at all. They just leverage the popularity of their videos to move merch. I've yet to see anything from them that impressed me.

Their gear looks decent from what I've seen. But their electronics are nothing that impresses me, their frames leverage other manufacturers parts, what they really excel at is marketing. And their bad boy image plays into that very nicely, it's a well proven formula.

These will sell well but I wouldn't expect to see many of them flying in groups unless they sell well enough that they can have dedicated gemini leagues for racing. (And why not, we've all seen similar less than top of the line products dominate their field because they were well marketed while better options languished in obscurity because they didn't have the publics eye.)

To me they're not that far off from DJI and are equally attractive to me.


Value is tough to define. I'm cheap, but years of being cheap have taught me that there are places corners can be cut and places they just can't. On my fullsize dune buggy that's almost as old as me I'm still using the original 35 year old master cylinder even though when I bought the buggy the seller told me the cylinders needed to be replaced and even included a brand new set of Chinese made replacements. Except the brand new Chinese replacements worked worse than the worn out (then) 20 year old originals. I bought another set of Chinese replacements from a reputable vendor and they were better but still not as good as the originals. I ended up buying a rebuild kit for the originals that cost more than the full Chinese Cylinders - and haven't had a problem for 10 years.

Along the same vein I have no problem buying cheap Chinese "bar clamps" and billet aluminum accessories like rearview mirrors and various mounts - they work just as well and aren't something that can literally be life or death like brakes!

But at the same time I "downgraded" from a custom built race motor that would run 9k RPM and had people questioning where I hid the extra cylinders - to a stock 90hp motor pulled from a street car who's owner was swapping the 4cyl for a v8. My buggy may not be quite as fast anymore - but it has a much more usable powerband now, uses cheaper gas, and has cost me less in maintenance in 7 years than the race motor did in one year. My fun level has gone up markedly while my spending has gone down even more - that's some serious value in my book.


There are things I have no problems buying Chinese knockoffs of. But there are others that I just won't even consider buying.

A $15 frame may mean I could buy 10 of them for the same cost as a blackout....but....that doesn't do me much good when I pack it in early and head home because I broke something in a crash that a better frame would have shaken off. Yeah, I'd be money ahead...but I'd be flying hours behind. Which is more important is a personal question that each of us have our own personal answer for.
 

Cyberdactyl

Misfit Multirotor Monkey
Yes, it's a must to choose wisely among Chinese products. But there's no denying the Chinese have allowed this segment of RC to explode.

I'm very happy to see small startups and individuals choosing to refine a niche, designing and improving on quality . . . even if at a premium price. But if the multirotor hobby had only premium ground and air components it would be much like it was in 2008. . . only a few fanatics with expendable cash would be participating.

As I'm sure everyone is aware, Chinese manufactures scour websites like rcgroups and video bloggers like rcmodelreviews, so I have confidence they will take their knockoff products and improve them just enough to get a head nod from the hobby in general. We see that time after time.

I try my best to not poo-poo cheap Chinese, because it got me into flying, and I realize there are thousands of others who can't, or won't pay for $30 motors or $25 ESCs or $200 frames or $400 transmitters. . .
 

kah00na

Senior Member
Here's another "looks-like-a-BlackOut" quadcopter - only this one comes in at $16.99! I thought $30 was a steal! Either this is the cheapest carbon fiber available or they found someone with a large stash that was just looking to get rid of it.

RCX-H250GF-P1-RCX-H250GF-FPV-Quadcopter-Glass-Fiber-EMAX-RCT-RCTIMER-H250-01s.jpg

The fiberglass version comes in at $9.99.
 

Cyberdactyl

Misfit Multirotor Monkey
I have this weird idea of getting the $10 FG version, and a sheet of 1mm CF ($18, but plenty left over) and tracing the booms and epoxying them on. It would increase the boom strength and stiffness by at least 50% and only add about 16g. ;)

[edit] screeeech, I went through the order process and the shipping is $10.
 
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jhitesma

Some guy in the desert
Mentor
MRM posted on RCG about that frame and it looks like Mustang has one through his MRM ties:
http://www.rcgroups.com/forums/showthread.php?t=2229327

It's worth noting that the carbon version is actually carbon/G10 composite - the 5mm arms are G10 with a veneer of Carbon over them. Basically what cyberdactyl is talking about doing with the G10 version. And honestly I don't have a problem with that as long as they're honest about it. I've said it before and I'll say it again most of the use of carbon in multis is cosmetic rather than functional. The Twitchity prototype quad has only helped convince me of this further as the G10 has held up to some hard crashes just fine. CF can help shave a few grams and can be a touch stiffer...but flat sheet CF really isn't making good use of the material.

Laminates have a lot of benefits. Look at the bamboo/CF laminate from Dragonplate - great idea IMHO.

Now, I do have a problem with Chinese sellers advertising a frame as Carbon if it's only using carbon veneer over G10 without explaining that it's a composite product and not actually CF. But my complaint about that is more about it being misleading advertising than about performance.

I usually like MyRCMart and have ordered from them in the past. But I don't like them advertising that frame as CF without mentioning that it's actually a G10/CF composite.

(Disclaimer: MRM contacted me a week or so ago about doing a project with one of these frames. I didn't know anything about what the frame would be at the time I agreed to take on the project and still don't know much more than what's been shared in the RCG thread I linked. But I should have one on my bench in a week or so and I will have a thread here about it when it arrives. I'm not getting paid but I am receiving the frame and components as compensation so while the above is my opinion and I try not to be biased - I'm still only human and probably am a bit more biased than I'd care to admit.)
 
Well some progress has been made on my mini spider hex:

jfwH3wK.jpg

One of the problems I ran into with the DYS 1806 2300kv motors is that the screw holes don't all line up perfectly. I ended up having to use three screws only:

iowPDtb.jpg
emUIZr3.jpg

As you can tell, it's still in prototype stage with things not all properly wrapped up and tucked away.

I've got the Naze32 FunFly on there and I'm trying to dial in the motor mixes. Unfortunately I haven't had much luck getting it tuned, it keeps wanting to pitch/flip forward and throttle is incredibly sensitive.

It launches into the air at around 20% throttle and so I need to figure that out too. I changed the Thr mix on my transmitter to 80% and that was a mistake, it would get into the air and then lowering the throttle slightly below the 'launch' point caused the Naze to cut the motors completely.

I bumped that back up and adjusted the rear two motors (1,3) to 50% throttle on the mix but it still pitches and has sensitive throttle.

cmix 1 0.500 -0.5 0.866 1
cmix 2 1.000 -0.5 -0.866 1
cmix 3 0.500 0.5 0.866 -1
cmix 4 1.000 0.5 -0.866 -1
cmix 5 1.000 -1 0 -1
cmix 6 1.000 1 0 1
I'm thinking of setting motors 5 and 6 to 0 throttle, and trying to get it flying nicely as a quadcopter first, then add the additional motors and tune those two.

It's crashed a couple times from 2-6 feet, directly on the nose (breaking an antenna on my brand new D4R-II) and a couple times upside down.

I haven't got the cage on for this reason, plus I managed to lose one of my brass standoffs into the void.
 
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FinalGlideAus

terrorizing squirrels
Get rid of all those fancy mixes and do it in the Naze. A simple way would be to add throttle expo until your happy. Another way is to find the throttle percentage the hex hovers at and adjust the throttle midpoint to that value and then add 10-20 throttle expo to flatten out that point on the throttle. It's all done in Baseflight and works great.
 
Ahhh that's a good point I didn't think about adjusting the throttle midpoint.

Those cmix values are on the Naze, I am running 'mixer CUSTOM' after doing 'mixer load HEX6X', then I am using 'cmix' and those values to set the mixing for the individual motors. This is mostly to try to fix the pitching forward issue.

It's being compounded by the fact that the throttle is so touchy, so it's pretty much trying to instaflip forward at 1.0 throttle values on motors 1,3. With the values at 0.5, I was able to get it to hover for a few moments by pulling back on the elevator then giving it a little throttle, but it was too touchy to maintain control.

I'll try to take a video a little later, I've set it aside so I can work on soldering up my minimOSD :]
 

FinalGlideAus

terrorizing squirrels
The instaflip issue should be somewhere else. Naze should fly a hex perfectly out of the box so it sounds like there's something screwy in your setup. Have you got the board and sensor setup right? Is there any elevator trim in your tx? Maybe wipe the settings and start from default again.

Always get it running mechanically right first, then work on the basic setup/tune and then add the fancy mixes.
 
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cranialrectosis

Well-Known Member
Mentor
I concur with FGA. Instaflip is almost always due to connecting the ESC wires to the FCB in the wrong spots. Make sure the ESC for motor 1 is connected to M1 on the Naze and so on for all the ESC cables.
 
Nah not a motor connection issue, double checked them all and they are fine, plus it was actually able to get liftoff, which it wouldn't be able to if a motor or prop spinning wrong. It just pitches forward too much until crash. Going to make a video now.

So before I moved the Naze into the hex, I flashed Cleanflight onto it. After using Cleanflight configurator, I was not confident in flying the hex with that firmware. The Aux channels were all scrambled and really buggy. I would put the checkbox to high for an option, and then when I activated the switch some other mode would toggle. IE, I put headfree on the Gear switch, flipped the gear switch and horizon mode activated.

I flashed back to Baseflight on the Naze, did a factory reset, then went into CLI and pasted the dump output which I had saved prior to flashing cleanflight
 
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FinalGlideAus

terrorizing squirrels
Check that all six motors are getting the same full throttle individually by using Baseflight motor test screen but do it with the props on. Dangerous I know but motors will react differently with the props on. Then try tying the hex down and see what the motor throttle indication tabs do when you give it throttle. They should all come up the same amount. That will at least tell if the Naze is telling the motors to throttle up unevenly or not. It does sound like the issue is somewhere else though.
 
Here's the video showing what's happening:


I am holding elevator back for the initial take off, where it hops. The second time with the elevator not held back the forward pitch angle is even greater and it instaflips.

Check that all six motors are getting the same full throttle individually by using Baseflight motor test screen but do it with the props on. Dangerous I know but motors will react differently with the props on. Then try tying the hex down and see what the motor throttle indication tabs do when you give it throttle. They should all come up the same amount. That will at least tell if the Naze is telling the motors to throttle up unevenly or not. It does sound like the issue is somewhere else though.
Alright I think I will try to build a little pvc rig that I can get it locked into, that's one of the things I was thinking might be an issue.

I calibrated the ESC's directly from the transmitter by hooking them all up to a servo signal splitter and plugging them all in to the same signal/power. They all seemed to start, throttle up and throttle down evenly without the props. I then calibrated them a second time through baseflight and through the naze.

I also tested it without the props by arming it and giving it some throttle, then tilting forward/left/right/back and verifying the correct motors would speed up to compensate. Everything seemed to check out for the basic tests.
 
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FinalGlideAus

terrorizing squirrels
Are you trying to fly in a stabilized mode? If so switch to rate mode and see if that changes things as it will tell if it is the accelerometers. Have you calibrated the accelerometers?
 

FinalGlideAus

terrorizing squirrels
Mmmm. If you are sure the motors are all connected up correctly and that there is no trims or mixes setup in your TX (i.e. a brand new untouched new model memory) I can only suggest doing a firmware update which will wipe the Naze and revert it back to default settings and redoing the basic settings to get it to a hex. Don't simply dump and rewrite in the CLI as that may be copying a bad setting across also.

It really does sound like a trim problem if you're flying in rate mode. Nothing else should make that happen that I can think of.

I just thought of something. When you plug in the battery, turn on the tx and connect it to baseflight, in the receiver page the elevator, aileron and rudder positions on the green lines should be at 1500 when the sticks are centered. Are they?