Help with first build, motors too weak/battery too big?

[wlance007]

Hey all,
I am having some troubles getting my first quadcopter off the ground. I am using these parts from hobby king:
MultiWii NanoWii ATmega32U4 Micro Flight Controller
TURNIGY Plush 6A /.8bec/6g Speed Controller
hexTronik 5gram Brushless Outrunner 2000kv
GWS Style Propeller 4x2.5
Turnigy 1500mAh 2S 25C Lipoly Battery

The problem is I can't get the quad to lift up even when I have the throttle at max. I am not sure if the motors are not strong enough or if there is something in the code that is keeping the motor speeds low. I noticed when I arm the motors (by bring the throttle stick to minimum and tilting it to the right) they automatically start spinning despite the throttle being at 0.

On the hobbyking page for the motors it says the thrust can be 90+ grams. The battery weights 79 grams and everything else weights a little less. Could I get my quad to fly if I get a smaller battery?

Since this is my first build I figured something like this would happen. Should I bother trying to make this one fly or would it be better to invest my money in another quad and use this as a learning experience?

Thanks

 

[fengshuidrone]

Have you calibrated your ESCs? You need to do that using your TX and RX. Hook up the ESC to the throttle pin on the RX and run the TX from low to high to calibrate. If you check on YouTube you will find all kinds of videos about ESC calibration. I'm not real sure on this but I think you might have some overkill in the battery department when it comes to mah and excess weight. Pack weight of 79 grams seems a little heavy for a tiny quad. I'd look for something under 1000 mah. I could still be wrong on that though as I have not done any of the calcs that are available online to determine what size motor and battery to use with your air-frame which I know nothing about.

Also, with multiwii, it is normal for the props to spin slowly when the quad is armed. There is a line in the config.h file in your Arduino that can stop that. In your config.h file, down near the end, you will see this category:
/*********************** motor, servo and other presets ***********************/
/* motors will not spin when the throttle command is in low position
this is an alternative method to stop immediately the motors */
//#define MOTOR_STOP

Remove the two forward slashes from in front of //#define MOTOR_STOP
This will stop your motors from spinning when armed and at minimum throttle. Don't forget that you have to upload changes before they will work.
If you need more help with your config.h sketch, post your questions in the
MultiWii/NAZE/SP Racing F3 Forum
Which is a better forum to go to with MW related stuff
Just look down the list under Forums or click the link above.
You have a tiny little setup there compared to what I use but the principle is the same no matter the size. When you buy a Multiwii FC you need to learn how to manipulate your Arduino config.h file, get your PIDs tuned, center up your TX, and depending on what your quad is set up for, do any other number of coding tricks and research on what others have done to make theirs work the way you want yours to work. When you go MW you either sink or swim depending on your ability to deal with a steep learning curve. But, if you stick to it, the Multiwii is an awesome FC. Mine flies like its on rails. I'm always amazed that people will go out and spend literally tens of thousands of dollars on just a flight controller. I swear, for the $32.00 I spent on my Pro2 I got ten thousand dollars of controller. All I had to do is figure it out. I like mine because I can do waypoint GPS missions and stuff like that. As long as you adhere to standard safe flying practices like you would with a megabuck movie camera carrying octocopter like calibrating the compass, and programming a proper mission, not flying on bad GPS days and only flying with a GPS fix, it is as safe and reliable as the more expensive RTF pro rig carrying a six figure camera. I have toyed with the octocopter idea myself as my pro2 can do 8 motors.

 

[wlance007]

Thanks for the help! Other people have been saying get a smaller battery too. How small of a battery would you recommend? Would 500 mah be small enough or would it then be too small?