First tricopter build - help with ecalc site - what have I done wrong?

[gregreh]

Hi all,

Total noob so your patience is appreciated

I have ordered a Batbone kit and while I wait for my parts to arrive, I thought I would put figures into the ecalc website with the parts I've ordered to see what I got. Ive attached the results. I have a red warning about exceeding the the max current for the motor.



I've read on some other posts that this is not a figure to worry about and that it is the hover figures that is more important. Is this correct? If not what should I have bought differently?

Do you need to use 100% of the throttle? How do you prevent this? Limit settings on the TX?

I'm confused really as the parts I have used (other than the ESC's) are on the recommended page for the Bat Bone.

Motors http://hobbyking.co.uk/hobbyking/store/uh_viewItem.asp?idProduct=36809
Battery http://hobbyking.co.uk/hobbyking/store/uh_viewItem.asp?idProduct=26715
ESC http://www.hobbyking.com/hobbyking/..._motor_speed_controller_simonk_firmware_.html
Props http://hobbyking.co.uk/hobbyking/store/uh_viewItem.asp?idProduct=35234

I tried modifying the ESC to different rated ones but to no effect so Im confused as to how that Maximum motor amp figure is achieved?? By changing the prop size to 6" I can get rid of the warning but I'm not sure what to do or if I have ordered something wrong. Or am I worrying about nothing??

Thanks for your help/advice

 

[CrashRecovery]

If you go 100% on your throttle you will shoot up into the sky. I would run at least an 8" prop. You won't get the lift you need with the 6" props. What control board are you planning to use? Look at the older multi rotor videos ft does. The H quad is a real good one to help explain things. I never even come close to flying at 100%. Here are a few vids from the other day
http://youtu.be/DhuYpVm7UI4
http://youtu.be/XBsYkf8Tvig

 

[earthsciteach]

I don't see any problems with the motor/esc/prop combo that you ordered. The site recommends an 8" prop for that motor, motor states 7A max current and you have a 20 amp esc. You may NEVER go full throttle on the tri-copter unless you are trying to launch it into space.

I do recommend that you get a higher C rated battery, though - something like this: http://hobbyking.com/hobbyking/store/__11951__Turnigy_nano_tech_2200mah_3S_45_90C_Lipo_Pack.html

Since you have already ordered the battery, fly it. It may be just fine.

Welcome to the Flite Test Forum!

 

[Craftydan]

first off, relax. Ecalc is right, that motor is overpropped with an 8x4.5 at Wide Open Thottle (WOT), but a multirotor, if sized properly will usually fly at 1/2 throttle.

I will say those motors are on the small side for a batbone frame and a 3s2200, but I've seen others fly successfully with them. She should fly, but keep a watch on the motors for the first few flights -- really warm is perfectly fine, burining hot is bad.

edit: ok, ditto what everyone else said . . .

 

[cranialrectosis]

I fly 1450 KV Suppos with 2200mAH 30 and 40C batteries running 8045 props. I use this on a Bat Bone Tri-Copter and a Knuckle H quad. Both are screamers with PLENTY of power for acro and can lift light loads like a GoPro.

I fly at 6,030 ft above sea level and I get my ESCs warm and sometimes can make a warm motor. Due to my altitude, I use more throttle than most people do to hover.

At WOT, I may torch a motor, I don't know. 75% throttle and my copter will be gone forever. I have never hit WOT.

 

[Mustang7302]

The motor, prop, and battery combination you've gone with is just fine. The amount of time the motors will spend above 70% throttle is fractions of a second at a time. Enjoy the build and enjoy learning to fly!

A consideration you need to think about however is that those ESCs do not have a BEC to power the flight controller, and subsequently the receiver. Make sure you pick up a separate BEC and add it into your power distribution to the ESCs.

 

[gregreh]

Thanks all for your quick replies. A few questions...

What control board are you planning to use?

KK2.1

I do recommend that you get a higher C rated battery

Why do you recommend this? What does it achieve?

A consideration you need to think about however is that those ESCs do not have a BEC to power the flight controller, and subsequently the receiver. Make sure you pick up a separate BEC and add it into your power distribution to the ESCs.

I realised this after I got them. I have got 2 UBEC's, as I believe I will need one to power the receiver and in turn my kk2.1 board and one for the servo. Is this correct? If not I'm not sure how i'd wire it up?

Thanks

 

[El_AMPo]

KK 2 board separates the first motor positive lead from the rest of the motor leads, this is done to use a separate BEC for the controller logic than the ones powering the servo to avoid brownouts and some voltage drift derived from servo current draw.

In your case since the ESCs come without BEC, you can use one UBEC in M1 positive/ground lead to power the electronics (KK+receiver) and another one for the servo, but in my experience you can just use one UBEC to run everything and bridge the positive lead from M1 to M2 in the KK board (just like in the old days of diy kk boards) and it will be just fine.

You got a little bit oversized motors for a Tri, I prefer using a 800-1000kv ones with 9/4.5 or 10/4.5 props but it should be fine with the 8 inch props, just mix prop size and motor kv until you get half throttle hover.

The esc current rating are just fine in my experience, but check before flying the current draw at half and full speed for the motor and prop combo you are using it should be below 15A per motor to be on the safe side.

About the battery, the one you got is just fine but in the next purchase go for a bigger C rating one, somehow the mutirotors tend to deteriorate 25C batteries faster.

 

[earthsciteach]

A battery with a higher C rating will be better able to hold up to the high amp draw that the 3 motors will require. The C rating is related to the amount of current that the battery can provide safely. If the current requirement is too high, the battery will suffer an early demise.

 

[Mustang7302]

Traditionally a ESC will power the board and receiver from the M1 port. Ports M2 through M8 have a shared 5V rail which can be powered by an ESC on any of the ports which would be able feed a servo or other 5V power load.

You could probably use one BEC to power the receiver on the Data/Power port, this would also power the KK2. Then for the servo, you'd have to look at taking apart an extension cable by removing the power and ground from both three pin connectors and then replacing the power and ground wires on the servo side with the wires from the second BEC; the KK2 side of the extension cable would only have the signal wire in it. Pulling the pins out of the three pin connectors isn't too hard to do.

Unless anyone else can think of a way that doesn't include connecting the two power rails in the KK2 together, which could potentially have issues?

 

[Mustang7302]

He is using 7A maximum motors. That's 21A total possible current from a Tri-Copter, which is about 10C to a 2200mAh battery. A 25C 2200mAh battery is good for 55A current. Higher C batteries are not required, weight more, and only offer the peace of mind of swap-ability to future higher current builds (>18A per motor for a tri or >14A per motor for a quad).

 

[gregreh]

Thanks all. Very good info. Im surprised people are saying I may have not got quite the right set up, as other than the ESC's, I have gone with what Flitetest recommend on their store for the bat bones kit http://shop.flitetest.com/multirotors/bat-bone-tri-370-kit/ so I assumed it would be fine.

The amount of options and combinations is so baffling to the noob.

Would you say the combination of motor/props I have gone for is more 'acrobatic'? If so its a shame, as I really want this for aerial photography, so stability is more important to me than fast. Is it just a case of swapping out motors/props to get a more stable tri?

Oh well, I'm sure I'll be building more than one, as even flying my Hubsan X4 is addictive.

One more question - the ESC's come with 20 awg wire on input and output and 2mm bullets. Is it fine to use these for the wiring harness and to the motors? What size wire should i use from the battery, before it splits out to the esc's

Thanks again guys

 

[cranialrectosis]

There are many many ways to build a tri-copter and electronics is as personal a choice as underwear.

Flite Test recommends several motors, high side and low side for their kits. I have three models and have been flying my own builds since July 2012 and have never used any of the recommended motors (they were all out of stock).

Larger motors like the 750s and 1000kv motors spin long rotors 10" - 12" maybe bigger depending on what you need. This gives you a mountain of torque and power and is kinda like driving a big Harley Davidson cruiser bike.

Smaller motors like the 1380s with 8045 rotors give you thrust at high RPM like a Ninja or Katana crotch rocket.

The big Harley is stable and will carry more payload when you need it to. The little Ninja is quicker and more responsive when you need it to. You may get better battery life on the larger 750-1000kv motors. NEVER learn to ride on a Harley. Always learn on a light bike. I say the same with copters. Keep it under 1kg to learn.

You can use expos on your remote to make the Ninja cruise and be less 'twichy'. When you are ready to rock, small motors allow for fantastic performance.

IMO, it is FAR FAR easier to learn on the lighter, faster, more responsive motors. Here is why:
1. They weigh less and therefore the copter weighs less and therefore has less inertia when it crashes (and you WILL crash). Smaller motors tend to mean fewer and less serious breaks in crashes. Less to pay for crashes tends to mean willing to try stuff and learn faster.
2. Smaller motors are cheaper to replace when you kill one.
3. Smaller motors do not tend to require so much balancing. If the balance is off on a large motor or rotor, the copter will have flight issues. Smaller motors are more forgiving here.
4. Some people like smaller faster motors for video. They say they tune out better and make for smoother video. So far, I concur.

Learn to fly on small quick motors. When you are ready, go up to something larger. The FT kits can handle both ends of the spectrum within reason. What you have should be a screamer. I predict you will hit hover <> 50% throttle and be whizzing around the park in no time (assuming you don't have to wait for shipping from China) .

 

[gregreh]

Hi all, my batbone tricopter took its maiden flight this morning, so just wanted to say thanks to everyone who offered me advice

Cheers

 

[Craftydan]

Pics or is didn't happen!!!!!

Congrat's Gregreh! It's always great to hear another one takes to the air!

So what do you think of it so far?

 

[gregreh]

Thanks craftydan!

Cant believe it flies and I shot this on my first day flying!

http://www.youtube.com/watch?feature=player_detailpage&v=-12M339Xp30

 

[peteparise]

I'm working through the process of selecting motors for a tri and/or hex using the kits here and matching props/motors/esc to the finished rigs are a challenge. I'm enjoying the great feedback you've been getting on this thread. What did you end up using on your tricopter?