Design Question

[calisto51]

I am starting the design the main deck is made from 6mm ply. The booms from 14mm square pine. I am using a KK flight controller V2.0. I have the motors so they are 120 Degrees apart.  I have some questions.
I have marked the centre point in the top deck, how important is it to have equilibrium around this point when using a FC with gyro';s.
Is it better to locate the FC over the centre point.
No manual came with the FC board which is not a problem but I noticed a small arrow marked forward. I take it that';s how it should be mounted to enable the gyro';s etc to work correctly.
I have yet to choose the motors and I am delaying this until I calculate the mass of the model.  I will post my design interpretation once I have completed it

[Gaza07]

Hi Calisto51 you are correct the arrow is supposed to be pointing forward it is the way the gro and acc will be setup to work correctly, you are always better of getting your flight controller in the center, I have built wooden multi';s before and found 3mm ply good enough for the main plates 

[calisto51]

I have some 3mm ply what about the centre balance is that important

[Gaza07]

I havet really got any experience with tricopters but if you drew a circle through all 3 center points of the motors the center of that circle would be where the flight controller should be 

[calisto51]

That';s how I have designed it, what I am trying to ascertain the importance of balance with respect to the flight controller. If everything balances around the centre point does that make the flight controllers work easier

[Gaza07]

Yes if its all out of wack it can make the controls pitchy and the gyro has to work a bit harder
I found this pic on the net it looks like they have it a little forward   



[attach=1]

[guest325]

Yes if its all out of wack it can make the controls pitchy and the gyro has to work a bit harder
I found this pic on the net it looks like they have it a little forward   



[attach=1]

It looks like it';s set at the centre of mass - which is how I';m looking at mine (when I finally get round to doing some more on it)!
You would need to know the weights of all your components to get at the centre of mass so you will need to have your final setup decided including all of the other bits.
Out of interest I';m doing mine in SolidWorks.

[calisto51]

I am also using solidworks so that once I have input all the masses of the various components and their respective positions I can get solidworks to do the calculations. Thank you all for your replies

[calisto51]

I have completed the design and estimate the all up weight is about 1.5 lb. old money 659 gms. I seem to have a bewildering array of motors to choose from. I read somewhere one should allow 100w per lb. Spread across three motors works out 50watts each, I plan to use a 30C battery. my end goal is to attach a video camera which will add weight. For now I just want to master the flight characteristics. I have looked at the E Power 2215 on Giant shark which gives a max current of 26amps and will require a 40amp ESC. I think this may have too much grunt depending on what prop I use. That';s another thing running IC engines its easy to spec a prop, with these electric thingy';s your spoilt for choice. Any suggestions would be most helpfull

[guest325]

I wouldn';t rule out those motors, a lot will depend on the batteries you intend to use - more volts = less amps.
If you go for 4S then you may only need a 30 A esc, I would have to have a look at these to tell. Higher volts is more efficient in terms of both power density and running the motor at lower current - it';s current that kills motors not volts (provided they are rated at the voltage you want to use)
I';ll have a good look at them and get back.

[guest325]

Have a look here
http://robotbirds.com/catalog/product_info.php?cPath=56_272_420&products_id=5449
If you scroll down to the link you get all of the details for prop requirements etc.
They also have a motor specifically designed for multicopters!
http://robotbirds.com/catalog/product_info.php?products_id=7109

[calisto51]

Thanks for that I have looked at the motor suggested EMAX MULTI COPTER MOTOR 2213-935Kv 3S WITH 2 PROPS  but I am unable to find any details on its characteristics as to what esc I would need.

[guest325]

Thanks for that I have looked at the motor suggested EMAX MULTI COPTER MOTOR 2213-935Kv 3S WITH 2 PROPS  but I am unable to find any details on its characteristics as to what esc I would need.

http://www.emaxmodel.com/views.asp?hw_id=1241
But I would use 30A esc';s  - probably RCtimer SimonK or similar, gives you a bit of headroom!

[Leigh]

Hi Calisto51,

I';ve just finished building a T-copter (my little intro thread here) and I';m using SunnySky 980kv (170w) motors from eBay - they came perfectly balanced and have no noticable vibration (as reported by a seismo app on my android phone, at least).  Most efficient prop tested on my thrust meter was a 10x4.5 SFP from Unmanned Tech Shop (the green ones) - balance wasn';t too bad on those, had to do a bit of sanding though.  Thrust results were 17.4A / 184W / 900g at full throttle.  Motors were mildly warm after 30 seconds at WOT, but that was without any prop wash hitting the motor (my test rig is a pusher setup).  I used an unflashed HK F-30A ESC for the test.

Hope that helps - I';m new to the forum, but I';m happy to help / share any experience with my fellow hobby enthusiasts :)

Cheers

Leigh
Aussie on the loose in Belfast, NI.

[calisto51]

Thanks for that hart I will check them out. I was very impressed with what you have achieved on your thread

[Leigh]

Thanks for the kind words!  Here';s a quick flight video from this morning after flashing SimonK:

Simple T-Copter flight after ESC flashing

[calisto51]

I have installed everything and programmed the KK2 board calibrated the ESC. The first problem I seem to have when doing a receiver test the stick movements although correct as shown on the board actually are reversed when I power up aileron and elevator. Reversing the servos on the transmitter gives the correct response. I am using a Futaba with a  FRSKY conversion. I was aware of the issue with the throttle but not the remaining channels. The second problem I have is when I bring the throttle up it pitches to the left. I have balanced everything. I am not sure where to go next?   

[nub]

should matter what u have to reverse as long as its all working the way it should be

is the pitching left in the air or trying to get it off the ground?

[calisto51]

trying to get off the ground

[nub]

did u calibrate the KK2, do the motors all start at he same time, are u taking off in manual or auto level mode, what firmware are u running?

maybe just have to pop it up into the air and it';ll be fine.