To Y6, or not to Y6...(aka my "next step" in the multi-rotor slippery slope)

[SkinnyDave]

To Y6, or not to Y6...(aka my "next step" in the multi-rotor slippery slope)

Hey All,

Finally got around to signing up for the forums here, been a fan of the FT stuff for a while now...I'm devouring all the content for all things multi-rotor and been flying my KK powered mini-quad for about 6 months now. Which leads me to my next project...the step up from the KK/Mini world which has me constantly thinking about flying non-stop!

Where I think I'm settling on is a Tricopter to start...but something that can be easily upgraded to a Y6...mostly for video purposes. I'd like to get into simple AP stuff with the tri - maybe a cheap gimbal/gopro setup after I get comfortable with flying...then when the hankering for more/bigger/better/etc. comes I can step up to a Y6 and get a better gimbal and drop a NEX sized camera on it (actually, BMD Pocket Camera). I'm looking to see if folks have thoughts/feedback on going this route - I'm still a bit newb-ish on a few aspects of it all, but spend a ton of time researching to *hopefully* save me headaches down the road (hence this post!).

Here's where I'm at for what I think I'd like:

Airframe:
-Pro Tricopter Delrin kit (looks easily upgradable to Y6)
-The Fortis Titan frame (it looks great, just not sure how simple a Y6 upgrade would be?)
-I'll probably start with wood arms for now, but upgrade to CF for Y6. Gotta learn how to crash...errr...fly first!

Motors: (want something 4s capable in future)
-SunnySky X Series (haven't nailed down which ones)
-Whitespy House Motor (775kv @ 170w)
-NTM Prop Drive Series (1000kv/126w @ 3s)
-Turnigy Multistar 2213-980Kv (165w @ 3s)
-Am I missing any other brands to check out? I haven't checked out "pancake" motors, but not sure I should go that route or what the up/down side to them are

ESCs:
Some 25-30a Simonk variant (I like the idea of the Whitespy stuff, or Afro seem fine)

Flight Control:
Ok, here's my real dilemma. I'm a tinkerer by nature (I bought a FrSky Taranis as my first radio...yeah, I'm that guy). I love the idea of tuning until my heart (or head) can't take it anymore. I think I'd like to go Pixhawk or another PX4 based controller...I really dig where that is heading, and seems simpler (though costlier) then MultiWii or Naze variants. DJI was a thought, but didn't realize until recently they don't do Tri's! Are there other folks out there using Pixhawk for tricopters...or is that just crazy? I've really loved my KK2.1 board, so I'm up for a bigger/better challenge and love the powerful GPS based stuff in the Pixhawk board.

RX/TX
-Already have FrSky Taranis and X8RE...really love it.

I'll figure out gimbal/battery and stuff like that as I go, for the Tri all signs point to Hi-Tec servos (thought I might be tempted on cheap metal geared knock offs) - but would love to hear some feedback/experience of anyone that might be in the same boat. I've checked out a few other Tri-Build threads, but didn't know if anyone had done a Y6 upgrade or not, and how that went. I've seen some pretty disastrous threads of newbs getting Y6/Ardu/APM builds right off the bat and that scares me, but somehow I think I'm smarter then that I'm not too afraid of crashing just yet...my little micro has taken a few falls and I've had fun with CA and some CF strips to keep that going!

Thanks for any help anyone can offer...I really REALLY love the FT community - what a great group of folks looking to help everyone and not really troll/flame as other places can be.

 

[CrashRecovery]

Skinny, first welcome to the forum from a fellow Marylander. Second the only things I see that a double motor setup gets you is a piece of mind if you loose a motor. Other then that do you really gain anything? The airflow from the props can not be that efficient due the twin props. I'm just guessing and going by what ive seen most bigger hex and octo copters only run the one motor.

 

[FinalGlideAus]

Welcome skinny Dave, the following is my thoughts.

What type type of Multirotor you depends on what you hope to achieve. The Titan tricopter is a great kit. I have one and like it although adding a gimbal to a tri really weighs it down and various things start to suffer. One way to tackle it is do a y6 but that has problems. You get more power but loose a good percentage of that from the lower motors due to efficiency loss. Plus you no longer have the excellent yaw authority of a tri so I kind of don't see the point of them besides being different. If you just wanted a really stable heavy lift platform a hex would be better. If you wanted some maneuverability as well then a quad would be better. But saying all that, if you're happy with the trade offs and love the idea of a y6 then go for it

If you want a flight control with full autonomous features then the Pixhawk is a good option although right now the APM boards are a better choice due to the Pixhawk being so new and untested and some features not fully implemented yet. If you want full GPS options don't get a cc3d or Naze as it's all very experimental. Unless you only want to hover don't bother with the Naza. Multiwii is an option but seems too much work without the solid performance of the APM.

Anyone who knows me knows I will tell you to run for the hills when thinking about NTM . Crappy quality, terrible bearings and horribly out of balance. Not an issue if just hovering around but once you strap a camera to it the vibrations become a problem. Generally I say stay away from ALL hobbyking motors. SunnySky and Tiger Motors are what I choose. You pay more but it's more than worth it in the end.

SimonK definately for the esc. Don't bother with something without. Blue series and the F20a series all work well when flashed. The. Afro's are fine but when you start using some higher performance motors or high poll count motors the Afros don't work so well. SimonK can suffer sometimes using these motors also but now BLHeli can be used instead of SimonK those issues can be fixed.

Hope those thoughts helped.

 

[trigger]

I am also considering a Y6 for my "video" platform, in the future, so I've started gathering some infos.

Advantage over a standard hex is the ability to fold.
Disadvantage is, of course, efficiency (which you can counter a bit by using a steeper pitch on the lower props).

I also like the ability to mount a front gimbal between the arms to be able to look up (which can also be done on a spider hex).


The Turnigy Talon tricopter frame is another candidate. It has been converted to a Y6 by some people, and it's not too hard to do. It uses round CF booms, but replacements are affordable.

As for the motors, I'd advice against the NTMs or the Multistars. I've been using Sunnyskys on my multirotors, and am happy with them, but I'm sure there are other affordable solutions with a better quality than HobbyKing motors.

FC-wise, the Pixhawk is a very solid choice, but expensive. APM clones can do pretty much the same things, but are much cheaper (although they have more or less reached their limits, while the Pix with its 32-bits processor has a lot of room to grow).
The Naze32 is surprisingly powerful (32 bits) and feature-packed (gyro/acc/baro/mag, and supports external GPS), and very cheap. It does not have (as far as I know) a mission planner though.

 

[FinalGlideAus]

While you can hook a GPS up to the Naze, it is not supported by the designer (Timecop hates GPS) and is very experimental as all after market hacks are. A friend of mine has been trying a GPS on his Naze and his testing in real life started as a RTL (Return To Land) and changed to a RTG (Return To Ground) about 1 km away ending up with burnt T motor and esc. There is no mission planer for the Naze either as no autonomous flight has been done as far as I know.

 

[trigger]

While you can hook a GPS up to the Naze, it is not supported by the designer (Timecop hates GPS) and is very experimental as all after market hacks are. A friend of mine has been trying a GPS on his Naze and his testing in real life started as a RTL (Return To Land) and changed to a RTG (Return To Ground) about 1 km away ending up with burnt T motor and esc. There is no mission planer for the Naze either as no autonomous flight has been done as far as I know.

Timecop hates a lot of things


I was browsing a thread about GPS and Naze the other day, and it seems that some people had some success.
Nevertheless, I agree that if autonomous flight is needed, APM/Pixhawk is, imho, the way to go.

If replacing hardware over time isn't an issue, I would suggest to start with a cheap APM clone, then upgrade to Pixhawk once it gains some maturity and the kinks are worked out.

 

[Cyberdactyl]

Here's a decent comparison of open prop, over-lapping props and over-under props.

I've come to believe if your 'simple' multirotor works for a dozen or more packs in a specific weight carrying condition and you keep diligent on inspection and checks, the redundancy advantage reduction of an open prop MR is close enough in reliability to an over-under flyer to be a close subjective call. Also consider, in a crash there's much more to ruin with twice the motors and ESCs, and since the mass is close to double, the odds of doing more significant damage goes up as well.

https://www.youtube.com/watch?v=tFJyE3Uns3o

 

[trigger]

Here's a decent comparison of open prop, over-lapping props and over-under props.

I've come to believe if your 'simple' multirotor works for a dozen or more packs in a specific weight carrying condition and you keep diligent on inspection and checks, the redundancy advantage reduction of an open prop MR is close enough in reliability to an over-under flyer to be a close subjective call. Also consider, in a crash there's much more to ruin with twice the motors and ESCs, and since the mass is close to double, the odds of doing more significant damage goes up as well.

https://www.youtube.com/watch?v=tFJyE3Uns3o

That was interesting, and pretty much what I was expecting.
I'd still love to see a test with coaxial motors using steeper pitch on the bottom, to see how much it affects the results.

One commenter made a good point though : on a coaxial configuration, you have half as many arms, hence some potential weight saving.

Finally, I think the main advantage of the Y6 or hex configuration over a quad isn't redundancy as much as it is lifting power.


Anyway, to me, the choice comes down to personal preference ; we're all willing to make some trade-offs to fly something we like.
I'd fly a Y6 or a spider hex over a standard hex any day because I think it looks cool, even if all the math and experimentation in the world proved it's a little less effective

 

[SkinnyDave]

Interesting perspectives - thanks guys!

I do know the Y6 is a bit of an oddball for configuration...I was going down that road just because of the redundancy/failure idea that if something where to go there seems to be a little (albeit not a lot) more evidence that a Y6 handles a motor/esc failure a little better in air. I was aware of the effecieny loss as well, but I kind of figured I'd be OK with that if it meant I had something slightly more portable and slightly less resistant to wind (although I think the jury is still out on that). Something I kind of always thought might be an issue in a traditional hex also is wobble on decent (lots of prop wash, big surface/disc area, etc)...I don't know why I'm kind of fretting over small stuff like that, but I guess that's where my brain is focusing on now! If I were to completely disregard me focusing on the Y6 part of it...does anyone have any heavy (ish) lift capable tricopters? I know that throws the redundancy thing out the window...and maybe defeats why people choose tricopters in the first place, but just thought I would check!

Good to know about NTM's as well...I've always heard good things about SunnySky/TMotor so I think I'll stick in that realm for sure. I might start on the lower end of those brands before I have a real big need for the higher end stuff.

I don't know if I'll go with Pixhawk right away, whitespy does have a "RTFHawk" that looks Ok...I'm pretty fascinated by the open source brew-ha-ha that is going down right now and they do have some valid points back and forth. The speed at which things are developing/changing are pretty insane...APM is the more robust platform and I think in the end if this obsession of mine grows it should grow with me. I'm sure I'll be using the FC at about 20% of it's capacity by just flying in circles around a tree in my field I think all the pro's are going to fall in love with the Naze as it get's developed more...it's tiny, powerful...and seems like a great little FC. My KK has a great return to ground feature - I don't even have to set it up on a switch on my TX!

 

[Cyberdactyl]

I don't quite buy the argument of saving weight by having half as many booms for an over-under.

Most all 'nicer' over-under multirotors use carbon fiber booms. For example, a large 18mm diameter carbon fiber tube, 24" long with a 1mm wall only weights ~40g. If you're building an octocopter with huge 350KV motors, that's only 160g (40x4)increase in mass over an over-under using the same size four booms. The additional motor mounts can be negated since more robust mounts would be required on an over-under mount. You WOULD have more connection components at the main plates, but that would amount to insignificant increase in mass up to around 250g depending on the design. When the AUW lifting capacity for something like this is upwards or more than 6000g, an extra 2-4 hundred grams seems insignificant for the increased efficiency of open props.

 

[trigger]

I don't quite buy the argument of saving weight by having half as many booms for an over-under.

Most all 'nicer' over-under multirotors use carbon fiber booms. For example, a large 18mm diameter carbon fiber tube, 24" long with a 1mm wall only weights ~40g. If you're building an octocopter with huge 350KV motors, that's only 160g (40x4)increase in mass over an over-under using the same size four booms. The additional motor mounts can be negated since more robust mounts would be required on an over-under mount. You WOULD have more connection components at the main plates, but that would amount to insignificant increase in mass up to around 250g depending on the design. When the AUW lifting capacity for something like this is upwards or more than 6000g, an extra 2-4 hundred grams seems insignificant for the increased efficiency of open props.

Oh, I agree that in the case of CF, the weight saving isn't that much (and far from compensating the loss in efficiency).
Still, ~400g is the weight of a 5000mAh 3S lipo.

In any case, I'm not arguing that a Y6 can rival with an open props hex in terms of efficiency. I'm just saying that it would be interesting to see some actual number for coaxial props with a steeper lower pitch, as well as taking the slightly lower AUW into account (or the extra battery, if you allow me to put it this way).
Just to see how it compares to the 25% loss from the test in the video you linked.

 

[Cyberdactyl]

Actually 400g is like a 5S 2200, but still . . I think the net gain percent in efficiency, or payload capacity and time in flight would edge out the over-under.

However, there's a lot to be said for the 'cool factor' of an over-under.

 

[cranialrectosis]

Y-6s have an inherent cool factor. Then again with the right frame, so do hexes.
http://forum.flitetest.com/showthre...ium-Engineering-Super-Simple-Spider-Hex-build

The Y-6 will lose some maneuverability from the tri and (all else being equal) will have less thrust than a hex. I think most folks who build them do so because they want more thrust than the tri, don't mind losing some acro ability and want something different.

I too thought about building a Y-6. What made the decision for me is that with a copter your rotors are not just for thrust. The rotors are your flight control surfaces. In a Y-6 the lower rotor makes the top rotor less efficient for thrust but you know that.

I believe the top rotor wash makes the lower rotor a less effective flight control surface and I suspect also that the lower rotor makes the top rotor a less effective flight control surface.

I want to fly acro. The good acro flyers fly multirotors almost like a fixed wing, using speed and momentum to do better stunts. When flying an acro copter I am using each side's rotors like wings. The offset on a hex or octo makes the rotor profile wider and the 'wing span' longer making for better 'cornering' and braking ability. The swooshyness of a tricopter that makes them so much fun to fly is due to flying forward and making banking turns.

These aspects cannot be exploited without speed and the speed is best controlled with large control surfaces.

This is why the Warp Quad String Theory frame flies so much better with 6" rotors on 2S than it does with 5" rotors on 3S.

The Y-6 doesn't work for me because I am an acro junkie. I don't need or want GPS or expensive flight controllers or robots that fly my copter for me. If you want more thrust but less acro than your tricopter the Y-6 may work well for you. If you want acro and/or power, go with the hex or stick with the tri.

Of course, this is from the guy who just had to try the three bladed rotors despite all the warnings...

 

[SkinnyDave]

I'm definitely seeing how personality comes into play for what kind of MR you fly

I'm the guy that wanted to car that does 0-60 in "X" seconds but regularly gets called a grandpa driver and slow poke by my wife/kids...so I guess that tells you how I like to fly my multi rotors (at least at this stage in my skill level).

Thanks for all the feedback...I'm slowly building shopping carts all over the web already...now...how to explain this to the wife...they care about yaw control, right?

 

[cranialrectosis]

Home made flying toys are art and as such are always subject to personal tastes.

I think we would call these modern performance art as we tend to smash them.

Wait, does this make us rock stars??

 

[FinalGlideAus]

Love my Naze! It beats any other basic controller by a healthy margin. It's just if you're looking for autonomous features and return to land, loiter and so on you be better off with a Pixhawk/APM board rather than risking your expensive multi for no reason. GPS has caused most of the flyaways when it's supposed to save you from them. There is a lot of setup to ensure it doesn't happen. I'm not flying my Titan/APM setup right now as I'm not happy with the GPS setup and won't until I am.

It's true the Pixhawk is the way of the future but the APM boards are tried and tested and youve got a loooong way to go before you outgrow it. The "mygeekshow" guy is using his APM to fly across the USA autonomously. How much more do you want

 

[Balu]

Do the Naze32 boards have problems with GPS flyaways too? I was just thinking about buying one to upgrade a level.

PS: @FinalGlideAus, your forums inbox is full.

 

[Tritium]

An errant GPS satellite has been identified and is due to be repaired soon. This satellite has been sending erroneous data for a while now causing all sorts of issues.

Other flyaways have and do result from improper setup / or build due to haste to fly and or ignorance of the user in proper setup procedures. Then there is the errant cosmic ray which occasionally flips the wrong bit AND the SUN has been very active lately as well with quite a few flares and radio blackouts.

Thurmond

 

[FinalGlideAus]

Do the Naze32 boards have problems with GPS flyaways too? I was just thinking about buying one to upgrade a level.

PS: @FinalGlideAus, your forums inbox is full.

Not for everyone but it is an experimental thing on the Naze since it's not factory supported. If GPS and RTL are key to your copter then possibly an APM board is probably the better choice right now. If you like to fiddle then try it on the Naze. I'm sure people will get it working more reliably in the future. GPS requires a lot of things to be right to work well and having only one thing go wrong can give you a bad day if you rely on GPS.

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