Building a hexacopter

[mediaguru]

Update on my build:

Built an electronics platform on the top of the bird which also serves as the GPS platform. My dome has a GPS pocket, but the SuperX GPS is too big to fit.

Receiver, voltage regulator, battery wiring, dome, telemetry GPS, voltage sensor all installed.

For the first time I attached power to the bird, just using a Phantom battery. The unit did not burst into flames, which is good. The PDB lit up, flight controller booted and LED indicator came to life. So the PDB, voltage regulator and flight controller all wired up.

Next is getting the RX and flight controller wired and then binding the TX to the RX.

Picked up two 5000mah batteries locally.

Finished dome mount setup as well.

Realized my power distribution board has a 5 volt output, so I'm toying with getting rid of the voltage regulator to save a few grams and some accessory space.

 

[The Editor]

Hi Mediaguru,

I have just picked up/stumbled upon this post - Nice to see some other user going for a self build option.

I built myself a FY690s some time ago and have been having a blast with it ever since. In fact my Phantom has been relegated to it's flight case for a couple of months now. The FY690s is way more stable in windy conditions than the Phantom ever could be and I get 20 mins+ flight out of the craft fully loaded with 2 x 5000mah packs, 3 axis gimbal, iOsd, Vtx etc etc. Very pleased with the whole set-up. My AUW is around 3,360g.

You've probably done your homework but what combination of motors/esc's did you go for? Do you know what your AUW is going to be as you need to be very careful with your choice of motors for g/thrust together with a careful choice of prop pitch.
Obviously if you take your AUW and divide by six that will give you your thrust per motor required but this will be to just get airborne only. You want to double it and add 10 - 20% overhead to give yourself a combination that will actually fly.
Also, watch out VERY carefully for esc timings on those pancake style motors. A lot of esc's just will not sync with the motors o will lose sync once stressed - Do a LOT of testing.... Prop weight can make a difference here as the heavier the prop the more inertia it has.

Remember - eCalc is your friend here (and fairly accurate as well) - http://www.ecalc.ch/xcoptercalc.php?ecalc&lang=en

Happy to help if you have any question as I've probably come across most problems during my build.

Oh, one final thing - since redundancy seems important to you (and it was to me which is why I went with a hexa). many, many people will run two packs in parallel to give them more flight time. Indeed I run two packs wired this way but nearly everybody I have come across connects them up using a parallel harness (either pre-made or home brew). To me this seemed like a weak link in the whole redundancy chain since if ONE connector failed you lose total power. I thought 'There has to be a better way' so I decided to wire my packs using two independent power lines to the PDB. The end result is the same (two packs in parallel) but should you lose a connector or a pack fails on you, you still have a completely isolated power supply at the correct voltage feeding the PDB. You would notice a faster drop in voltage via telemetry and bring your hex in quickly for a landing but it wouldn't fall out of the sky.

Oh, and a final final(?) thing to watch out for - I'm guessing you know about the problems that can ensue if your esc's are non opto and have becs internally (assuming you are using the bec output)? Make sure you disconnect 5 of them and only use ONE positive connection for all of them otherwise horrible things will happen! This wasn't an issue for my since I didn't need 5 volts for anything - I run the Naza with PMUv2 and 5 volts supplies the FC with power for the Futaba RX being fed via S-BUS.

My build was basically:
Tarot FY690s frame
Extra battery plate and 12mm support rails
6 x T-Motor MN3508 20 580kv
6 x T-Motor 12x4 v2 carbon Fiber props
6 x DJI 30amp Opto esc's
DJI Naza M v2 with GPS
DJI iOSD Mini
Folding CF GPS mount
Futaba R2008SB RX
160amp Power Distribution Board - running EC5 connectors
Immersion RC 600mW Video TX
Fat Shark Spironet Ant x 2
2 x 5000mah Lipos wired in parallel through the board not the harness in case one connection fails
1 x 1000mah Lipo - to power VTX and gimbal
Arris CM3000 3 axis gimbal

That's my two pennyworth for now - if I can help with anything give me a shout.

 

[wkf94025]

I also just found this thread, and look forward to looking over the shoulder of you hex dudes. Liking MediaGuru's build log. Two questions in the moment:
1) How is the 3-axis SimpleBGC world? Huge time sink? Or delightfully tunable? Or maybe both? Or neither?
2) Ballpark total budget for a great hex? I know it depends wildly on many components, but assume a desire for long range, good FPV, 3 axis gimbal, and capacity for a good/great camera.

Very curios.

Kelly

 

[The Editor]

I also just found this thread, and look forward to looking over the shoulder of you hex dudes. Liking MediaGuru's build log. Two questions in the moment:
1) How is the 3-axis SimpleBGC world? Huge time sink? Or delightfully tunable? Or maybe both? Or neither?
2) Ballpark total budget for a great hex? I know it depends wildly on many components, but assume a desire for long range, good FPV, 3 axis gimbal, and capacity for a good/great camera.

Very curios.

Kelly

Hi Kelly,

To answer your questions:

1) Excellent platform and the introduction of 2.40b7 has (in my opinion) simplified the PID setup. It is VERY tunable. way way more than any Zenmuse out there. Basically EVERY parameter is tunable!
2) Very difficult question (and I try not to think about it too much :lol: ) but you can see my shopping list above. If you factor in the cost of a GoPro and say a Futaba T8J or similar on top you are looking in the region of $3,400/£2,125. Increase this if you want a better camera/gimbal combination.

Hope that helps.

 

[wkf94025]

Ed,

Thanks for the fast response. Glad to hear on the SimpleBGC 3-axis world. One more stepping stone away from DJI.

Sorry to be all about me, but if I already have cameras (GoPro's and small FPV cam), goggles, screens, VTx's, antennas, Duo receiver, Futaba 14SG and matching receiver, iOSD's, GPS trackers, and plenty of flux , what would you peg a good budget at? Seems the principal hex components I need are frame, ESCs and motors, NAZA, GPS, power subsystem, gimbal, landing gear, etc.

Also, are any of Air Hex using retractable gear, or is that just a gimmick?

Kelly

 

[The Editor]

Ed,

Thanks for the fast response. Glad to hear on the SimpleBGC 3-axis world. One more stepping stone away from DJI.

Sorry to be all about me, but if I already have cameras (GoPro's and small FPV cam), goggles, screens, VTx's, antennas, Duo receiver, Futaba 14SG and matching receiver, iOSD's, GPS trackers, and plenty of flux , what would you peg a good budget at? Seems the principal hex components I need are frame, ESCs and motors, NAZA, GPS, power subsystem, gimbal, landing gear, etc.

Also, are any of Air Hex using retractable gear, or is that just a gimmick?

Kelly

Hi,

Last things first: Personally I wouldn't bother with retracts unless you are going full 360 degree gimbal/2 man shoot etc. They also add a LOT of weight. They look way, way cool though but..... not worth it.

You nailed it on the components - that about sums it up.

You could say......

Frame - $160 - 220
6 x esc $150
6 x motors circa - $475 (for T-Motors - there are cheaper options out there but I wanted quality)
Naza M v2 with GPS - $300
Power distribution board - $20
Cables, connectors etc - $20
Gimbal - something like the Arris CM3000 - $320 http://www.hobby-wing.com/arris-cm3000-gopro-hero3-brushless-motor-gimbal.html
6 x T-Motor 12 x 4 props - $180

Total... circa $1,625 - $1,700 depending on Frame, Motor and Prop choice.

All the best

 

[wkf94025]

Thanks. I think I just met my next mistress!

Assuming no retractable, two performance questions of her: (1) max flight time (and speed therefore range) if I went GoPro+CM3000 as FPV primary? (2) How much camera payload can a good hex haul, assuming range and speed not the goal, but great stable footage? Assume NOT price sensitive on motors, props, batteries, etc. Is there a singular favorite amongst you all as to the next quality video+still camera above GoPro for UAV apps? Not looking to spend thousands on a major gimbal and Red or other, but maybe an incremental $1,000 USD on quality camera and gimbal upgrade if needed (beyond the CM3000 class).

Last question: estimated hours to build? (another one of those questions we don't often want to admit to ourselves...)

Kelly

 

[mediaguru]

Hi Mediaguru,

I have just picked up/stumbled upon this post - Nice to see some other user going for a self build option.

I built myself a FY690s some time ago and have been having a blast with it ever since. In fact my Phantom has been relegated to it's flight case for a couple of months now. The FY690s is way more stable in windy conditions than the Phantom ever could be and I get 20 mins+ flight out of the craft fully loaded with 2 x 5000mah packs, 3 axis gimbal, iOsd, Vtx etc etc. Very pleased with the whole set-up. My AUW is around 3,360g.

You've probably done your homework but what combination of motors/esc's did you go for? Do you know what your AUW is going to be as you need to be very careful with your choice of motors for g/thrust together with a careful choice of prop pitch.
Obviously if you take your AUW and divide by six that will give you your thrust per motor required but this will be to just get airborne only. You want to double it and add 10 - 20% overhead to give yourself a combination that will actually fly.
Also, watch out VERY carefully for esc timings on those pancake style motors. A lot of esc's just will not sync with the motors o will lose sync once stressed - Do a LOT of testing.... Prop weight can make a difference here as the heavier the prop the more inertia it has.

Remember - eCalc is your friend here (and fairly accurate as well) - http://www.ecalc.ch/xcoptercalc.php?ecalc&lang=en

Happy to help if you have any question as I've probably come across most problems during my build.

Oh, one final thing - since redundancy seems important to you (and it was to me which is why I went with a hexa). many, many people will run two packs in parallel to give them more flight time. Indeed I run two packs wired this way but nearly everybody I have come across connects them up using a parallel harness (either pre-made or home brew). To me this seemed like a weak link in the whole redundancy chain since if ONE connector failed you lose total power. I thought 'There has to be a better way' so I decided to wire my packs using two independent power lines to the PDB. The end result is the same (two packs in parallel) but should you lose a connector or a pack fails on you, you still have a completely isolated power supply at the correct voltage feeding the PDB. You would notice a faster drop in voltage via telemetry and bring your hex in quickly for a landing but it wouldn't fall out of the sky.

Oh, and a final final(?) thing to watch out for - I'm guessing you know about the problems that can ensue if your esc's are non opto and have becs internally (assuming you are using the bec output)? Make sure you disconnect 5 of them and only use ONE positive connection for all of them otherwise horrible things will happen! This wasn't an issue for my since I didn't need 5 volts for anything - I run the Naza with PMUv2 and 5 volts supplies the FC with power for the Futaba RX being fed via S-BUS.

My build was basically:
Tarot FY690s frame
Extra battery plate and 12mm support rails
6 x T-Motor MN3508 20 580kv
6 x T-Motor 12x4 v2 carbon Fiber props
6 x DJI 30amp Opto esc's
DJI Naza M v2 with GPS
DJI iOSD Mini
Folding CF GPS mount
Futaba R2008SB RX
160amp Power Distribution Board - running EC5 connectors
Immersion RC 600mW Video TX
Fat Shark Spironet Ant x 2
2 x 5000mah Lipos wired in parallel through the board not the harness in case one connection fails
1 x 1000mah Lipo - to power VTX and gimbal
Arris CM3000 3 axis gimbal

That's my two pennyworth for now - if I can help with anything give me a shout.

Hey thanks for the comments. I should definitely pick your brain.

I'll try to answer your comments as best I can.

I went with the Tarot 5008/340kv heavy lifter motors and hobby-wing pro 40amp esc's. The first batch of props are Tarot 1755's, carbon fiber.

Run that whole opto/bec thing by me again. Not following that.

I have a voltage regulator which I'm supplying 22.2v to the motors/escs. From an output on that I'm going into a voltage regulator which will power the FC and the RX. The dist board has 5 volt outs so I could get rid of the regulator and lighten it up by a few grams.

I'm going to run two 5000+mah lipos. Interesting comment about the redundancy of the battery connection. I might think a bit about that.

I have an Arris Zhaoyun gimbal. Haven't even started to figure out how I'm going to mount it.

Setup so far:

Tarot T960 Frame
XAircraft SuperX Flight Controller
FrSky Taranis TX
FrSky 8XR RX
2 pulse 5000mah 35c lipos
1200 watt power supply with lipo charger and paraboard
Tarot 5008/340kv motors
Hobby-Wing 40A "pro" ESCs
Tarot folding landing gear
Voltage regulator
FrSky telemetry GPS
FrSky telemetry voltage sensor
Arris Zhaoyan gimbal
Clear dome for top from badgerfly

There is an FPV camera built into the Arris gimbal. I don't have any other FPV stuff yet. Ran out of money. hehe

 

[extrememc]

I keep see the terms BEC and AUW in recent post. What do those terms mean?

What runs off 5v and does this power come straight from the PDB?

Here is my part list so far. I have a futaba T8F and receiver. Am I missing anything?

Parts List

Tarot 810 1,167.00
http://www.foxtechfpv.com/tarot-t810-he ... -1119.html


6s 5000 mah $116.00
http://www.foxtechfpv.com/6s-5000mah-li ... -1385.html

4114/320KV Motor 44.99
http://www.foxtechfpv.com/4114320kv-bru ... -1061.html

Motor Mount 24.99
http://www.foxtechfpv.com/tarot-new-25m ... -1080.html

PDB 2.20
http://www.hobbyking.com/hobbyking/stor ... duct=39317

Stand offs 3.99
http://m.hobby-wing.com/tl65b05.html

Plates 91.99
http://www.foxtechfpv.com/t810t960-main ... -1053.html

Clamp holder for gimbal mount 19.99
http://m.ebay.com/itm?itemId=251469057197

ARRIS ZHAOYUN 3-axis brushless gimbal 720.00
http://www.hobby-wing.com/arris-zhaoyun ... imbal.html

 

[wkf94025]

Which camera do you plan to fly on that hex, and do you plan to use a separate camera for FPV? Or use a video switcher?

Kelly

 

[extrememc]

Sony nex 5 or EOS M. Some camera for FPV.


Sent from my iPhone using Tapatalk

 

[mediaguru]

Which camera do you plan to fly on that hex, and do you plan to use a separate camera for FPV? Or use a video switcher?

Kelly

I haven't decided on a camera yet. The gimbal is setup for a Nex5 size. I may throw my Canon S95 in it for fun and testing. Its probably smaller than the Nex.

The gimbal itself has an FPV camera built in.

 

[The Editor]

Woah... lots of questions from everyone

OK - the terms AUW stand for All Up Weight. Basically if you get your hex and put it on the ground ready to take off so it's loaded with batteries, camera gimbal - everything you are going to fly with on it then put your hex on a set of scales that would be your AUW. It's a very important number because it is fundamental on how long you are going to get in the air, how many amps you are going to draw from your packs and how much strain you are going to put on your motors.
With any Hex you need to establish your AUW first. Then divide this number by 6 (or 8 if it's an octo). The resultant number will tell you how much thrust each motor has to produce to enable hover. However, nobody wants to just hover, we all like to fly around a bit and assuming you want your craft to hover at around mid stick you need to double these numbers and add 10-20% overhead.
eg; If your AUW for your craft was 3kg (3,000g) then your motors would need to produce 500g thrust each just to get airborne. In order to achieve meaningful flight you would need 6 motors that can achieve around 1.1kg (1,100g) of thrust each.
The amount of thrust a motor can achieve will be laid down by the manufacturer and will depend on voltage (3s or 4s pack etc) and prop length and pitch.
Too steep a pitch and you will draw too much current through the motor and it will overheat. Too little and the motor will need to spin faster and you will lose efficiency - all of the above effect your flight times.
A very good tool is eCalc -> http://www.ecalc.ch/xcoptercalc.php?ecalc&lang=en . It DOES have it's deficiencies but it will give you an idea of what combos work and what are way out of whack.

BEC stands for Battery Elimination Circuit. It's basically a regulator that will provide (in esc cases) a stabilised 5v supply. This can be fed to the flight controller and/or receiver but you should be mindful of how much current an esc bec can provide. If you over stretch them they will fail. I use the Naza M v2 with PMU. The PMU is in itself my bec so I use opto isolated esc's with no bec whatsoever.

@mediaguru - If you are going to use the 5v supply from one of your esc's the reason you should cut the other 5 positive leads off and only use one is because if you don't you will have 6 becs in circuit. Each bec will differ in voltage by a very small amount and you will have a conflict going on with all six in circuit - hope that makes sense. I AM NOT talking about cutting the wires that feed the motors here I am ONLY talking about the bec outputs.

@wkf9425 - Max flight time is such a variable because every component plays a part in a self build craft. However as a guide, my FY690s has an AUW of around 3.5kg and I get a comfortable 20 mins in calm conditions and around 18.5 mins in windy/gusty conditions. This pulls around 7,800mah from my packs so well within the 80% rule.
With regards to payload... the bigger the hex, the bigger the payload (generally). A criteria for my was portability so I didn't want to go huge. I also knew I was only going to be using a GoPro with this set-up so I designed the whole hex around theose sort of weights (including the Arris CM3000).
I favour T-Motors for motors and props - they are not the cheapest but they are VERY good quality and at the end of the day the only thing that is keeping your money aloft is the motors and the props !! :shock:

Hopefully that's answered your questions guys - anything else shout.

 

[wkf94025]

Thanks Editor! Priceless education.

Kelly

 

[mediaguru]

A very good tool is eCalc -> http://www.ecalc.ch/xcoptercalc.php?ecalc&lang=en . It DOES have it's deficiencies but it will give you an idea of what combos work and what are way out of whack.

BEC stands for Battery Elimination Circuit. It's basically a regulator that will provide (in esc cases) a stabilised 5v supply. This can be fed to the flight controller and/or receiver but you should be mindful of how much current an esc bec can provide. If you over stretch them they will fail. I use the Naza M v2 with PMU. The PMU is in itself my bec so I use opto isolated esc's with no bec whatsoever.

@mediaguru - If you are going to use the 5v supply from one of your esc's the reason you should cut the other 5 positive leads off and only use one is because if you don't you will have 6 becs in circuit. Each bec will differ in voltage by a very small amount and you will have a conflict going on with all six in circuit - hope that makes sense. I AM NOT talking about cutting the wires that feed the motors here I am ONLY talking about the bec outputs.

Thanks for the BEC explanation. I basically have two BEC's then, one built into the PDB and the other being my voltage regulator. I'm planning on running from one or the other directly to the FC and RX. That setup does not utilize an ESC as a BEC then, if I'm understanding correctly.

That being said, you are saying that only one 5V lead from the I/O of the flight controller should have the positive lead?

 

[The Editor]

A very good tool is eCalc -> http://www.ecalc.ch/xcoptercalc.php?ecalc&lang=en . It DOES have it's deficiencies but it will give you an idea of what combos work and what are way out of whack.

BEC stands for Battery Elimination Circuit. It's basically a regulator that will provide (in esc cases) a stabilised 5v supply. This can be fed to the flight controller and/or receiver but you should be mindful of how much current an esc bec can provide. If you over stretch them they will fail. I use the Naza M v2 with PMU. The PMU is in itself my bec so I use opto isolated esc's with no bec whatsoever.

@mediaguru - If you are going to use the 5v supply from one of your esc's the reason you should cut the other 5 positive leads off and only use one is because if you don't you will have 6 becs in circuit. Each bec will differ in voltage by a very small amount and you will have a conflict going on with all six in circuit - hope that makes sense. I AM NOT talking about cutting the wires that feed the motors here I am ONLY talking about the bec outputs.

Thanks for the BEC explanation. I basically have two BEC's then, one built into the PDB and the other being my voltage regulator. I'm planning on running from one or the other directly to the FC and RX. That setup does not utilize an ESC as a BEC then, if I'm understanding correctly. - Correct

That being said, you are saying that only one 5V lead from the I/O of the flight controller should have the positive lead?- No, only ONE lead from an esc bec output should be used but as you have a regulator on your PDB and you intend to use this I wouldn't worry.... You just will not be using your esc's to provide 5 volts for anything so that's fine

 

[mediaguru]

Thanks The Editor for the great information. It is VERY helpful.

Regarding ecalc I signed up and paid for a membership. But my motors (Tarot 5008/340kv) are not on their list. I also get stumped on some of the selections.

 

[The Editor]

Thanks The Editor for the great information. It is VERY helpful.

Regarding ecalc I signed up and paid for a membership. But my motors (Tarot 5008/340kv) are not on their list. I also get stumped on some of the selections.

If you signed up for membership and paid the 0.99c you should have access to the full motor listing? Tarot 5008/340's are on that listing. See here -> http://www.ecalc.ch/calcmember/components.htm (use the dropdown list to select Tarot and it's the third one on the list)

 

[mediaguru]

Never been able to properly login to get the full lists. Turns out my membership is screwed up and they have me for propcalc and not ecalc. Sent them an email asking for that to be fixed.

 

[The Editor]

Never been able to properly login to get the full lists. Turns out my membership is screwed up and they have me for propcalc and not ecalc. Sent them an email asking for that to be fixed.

Ahhh... that will be it then ! They should sort that out for you pretty quick.

Yeah some of the selections can be pretty daunting but the more you get used to it the easier it becomes... Honest !!

I find it easiest to select 'good' for motor cooling then select your number of rotors (6 for a hex obviously) then enter your AUW - You have to do a bit of calculator work here but if you take the weight of EVERYTHING and add it all up.... that means motor weight, prop weight, esc's, frame, batteries etc, etc (you get the idea.... make sure you throw in a few grams for the weight of screws, wires hardware etc). Then select 'Inc Drive' since you are working with AUW. If you don't select this ecalc will try and work out the AUW for you by using data it has on specific components. I found this method not as accurate as working it out yourself.
Enter your approx field elevation as altitude does make a difference on flight time. You can leave temp and air pressure at default unless you REALLY want to enter them accurately.

Battery, Pack and cell count is straightforward - try and enter as near to the 'C' rating as you will be using to give better results and I always enter 'full' for charge state.
ESC's speak for themselves and should automatically pick up the relevant data.

Enter up your motors (once admin have sorted out your hiccup or you maybe able to enter up custom fields to fit in with your Tarots)

Finally prop selection - I always enter this manually as I like to play around with different prop configuration on pitch and length etc to see where that takes me not only on flight times but on motor temp, rpm (make sure you do not go over your prop manufacturers max or you run the risk of props shattering).
Your props will always have two blades (unless you are running tri-props) and your gear ratio will always be 1:1.
You can freely alter length and pitch to see how it effects your design dynamics.

Finally, once you have your results.... apart from the flight times you should pay attention to the current at max figure as this could go over your PDB rating and AWG selection on your cables !! Also watch your motor temperatures.You are also looking for maximum efficiency at hover and also you need to get your hover percent somewhere around 50% (give or take) - It's no good having your multi hover at say 80% stick as you then have no overhead for climb outs etc.

Hope that helps.