construction of the HEXA frame & camera mount

While still waiting for the TX/RX to arrive,

I started to design and build the HEXA frame for upgrade

each arm is made of 14x14mm 1mm wall square tube,

arm length: 40cm from center, 80cm from motor to motor.

center plate is 16cm dia., two 2mm thick plates.

Also, i have done weight calculations and measurements:

Frame: 470g

camera mount: 460g

motors: ~500g

battery:~500g

DSLR camera: 950g

Lens: 550g

electronics (ESC, pilot, servos): ~500g estimated

For a breathtaking scary total of 3930 GRAMS

well, that scared me a bit, i will consider:

-drilling plenty holes in the arms and everywhere i can to take material off

-using a lighter DSLR (can save max 300g)

-using a smaller swivel plate for the camera mount (though the smaller ones have much smaller center hole, thus heavier)

here are a few pics of the construction:

If the motors will allow this and that beast will take off,

i will use a 8000mAh 14.8v battery, it's around 900gr

Still have to think about / order:

- wireless USB solution for connecting the DSLR to ground

-wireless video and cheap tiny camera

- try out HK's 9050 3-blades props if they are better than the jDrones 12x45

-design landing gear

-design a swivel mount for the camera yaw axis

Comments are appreciated !

I don't like that kv-throttle relationship, even if it may be true if prop, motor, and batt remain unchanged.

The problem is that RPM can go too high where the SF (Slow Flyer) are not suitable and the motor overpowered.

Take the 3542-1000 you suggested for example:

Looks like really nice motor which I like, but watch one of the reviewer's submited data:

9x4.7 11.47v 19.9A 230W
9x6 10.98v 30.9A 343W
10x4.7 10.92v 32.5A 359W
9x7.5 10.78v 37A 401W
11x4.7 10.71v 39.6A 426W

As you see 10x4.7 and 3S is pretty much the maximum you can put on as it is already taking almost all the juice this motor can give (max current rated at 35Amps).

So if you want to use larger prop and/or 4S batt you have to look for a lower kv (or a more powerful, say bigger) motor.

Note: this rough "analysis" led me thinking that the "ArduCopter official heavy duty motor" 2836 motor from JDrones, DIYDrones and so on, may be ok with 10x4/4S and 12x4/3S, but 12x4/4S may be too much for it.

Of course, I have no experience with this motor so I can be absolutely wrong, (and if I am, I would like to know)

As you can see prop/motor/batt combination is kind of black magic sometimes that I am just a newbie.

If all this gave you headache keep your 12x45/2836-880 combination but try with 3S batt first.

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Comments

ARHEXA April 14, 2011 at 7:30am

ouch !! i just got hit by the 12x45 BLACK

and yes,

that bloody hurts.

makes you think again about ordering the composite ones.... :D
ARHEXA April 14, 2011 at 6:32am

Jani, that's nice to know.

could you tell by your tests until now/ or your instincts -

would my hexa do well with 6 of the bigger motors (orange) and 12x4.5 props for a total of 4-5kg ? (900g per motor)

or will it be too on the edge and dangerous for the motors ?

when i think that these motors are designed for use with an arducopter frame about 2-2.5kg, and mine is 4.5kg, that scares me a bit, even if i have 6 motors and not 4...

and how about the composite props being better performers than the "black epp" ones ? is it right ?
Developer

Jani Hirvinen April 14, 2011 at 6:26am

We can make more tests for those motors, smaller 2830-358 motors runs really nice with 4S and 10X45 props. We are using those on our proto hexas. Bigger 2836-358 motor also supports 4S. Currently building new test bench to get even more data from the motors.
ARHEXA April 14, 2011 at 5:56am

totally sounds black art...

i already ordered 6 motors and props and ESC's.

so i'll try with that,

will try to estimate if the load is too high on the motors

(this can be done by simple current measurement while the copter is hovering, right ?

Ivan,

here - 6" lazy susan
I.S. April 14, 2011 at 5:48am

I don't like that kv-throttle relationship, even if it may be true if prop, motor, and batt remain unchanged.

The problem is that RPM can go too high where the SF (Slow Flyer) are not suitable and the motor overpowered.

Take the 3542-1000 you suggested for example:

Looks like really nice motor which I like, but watch one of the reviewer's submited data:

9x4.7 11.47v 19.9A 230W
9x6 10.98v 30.9A 343W
10x4.7 10.92v 32.5A 359W
9x7.5 10.78v 37A 401W
11x4.7 10.71v 39.6A 426W

As you see 10x4.7 and 3S is pretty much the maximum you can put on as it is already taking almost all the juice this motor can give (max current rated at 35Amps).

So if you want to use larger prop and/or 4S batt you have to look for a lower kv (or a more powerful, say bigger) motor.

Note: this rough "analysis" led me thinking that the "ArduCopter official heavy duty motor" 2836 motor from JDrones, DIYDrones and so on, may be ok with 10x4/4S and 12x4/3S, but 12x4/4S may be too much for it.

Of course, I have no experience with this motor so I can be absolutely wrong, (and if I am, I would like to know)

As you can see prop/motor/batt combination is kind of black magic sometimes that I am just a newbie.
If all this gave you headache keep your 12x45/2836-880 combination but try with 3S batt first.
Ivan April 14, 2011 at 5:31am

Can you give some more info where you bought (or how you made) this:

https://storage.ning.com/topology/rest/1.0/file/get/3689399096?prof...
ARHEXA April 14, 2011 at 4:48am

i didnt get the kv thing yet...

after all, low kv+high throttle = high kv+lower throttle

so i better have the same speed with headroom to more throttle....

i get that there is also the power or strength - the current rating,

but if i run the 1000kv motor with low throttle, it will still have greater power than the one i have now, and will spin faster on the same throttle...
I.S. April 14, 2011 at 4:34am

you're fast man!

I have no deep CFD knowledge, but the idea is that stiffer (say higher density plastic, wood, composite, CF...props) "cut the air cleaner" so they rattle less than softer props thus being more efficient.

The con is that in case of an accident they may may break easier or put higher stress on motors shaft.

The 3530-1400 looks like the proper upgrade in size but too high kv.

The 3542-1000 is quite a monster, and kv rating on the higher edge too, but it may work with 10x5 props and 3S lipo though.

I suggest looking for lower kv ratings and pick a bunch of motors and props sizes to figure out the best combi.
ARHEXA April 14, 2011 at 4:14am

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=...

what do you think ?
I.S. April 14, 2011 at 4:11am

by the way what other bigger Turnigy motor have you thought about?

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