yes i guess i learnt it the hardway... i thought the Flight Controller would be taking care of the motor rotation directions but it seems pure +ve & -ve have to be swapped to get the desired direction.

is this the case with just this mini quad or also with other big motor quads? does polarity of the motor needs to be looked into before getting it on with the wiring? does the ESC or the Flight Controller do nothing in KK or Aurdino boards regarding prop roation??

So thats always it has to be with multirotors. If one motor is spinning CW then other should be CCW. Thats why you get 2 x CW props and 2 x CCW props

hi satya... don't know how but only 2 motors are running when i push the throttle stick maybe i smoked the board..... will eat it with a pizza next time [Flavour : Smoked FC  ]

i have placed an order for a new V939 last night... can you make it avaliable to me in by Friday evening in Pune?? need to push things fast...

also how to identify the CW and CCW props?? i mean with this mini quad and also in future...

With this one the best way is to first solder the connecters as per the instructions - two regular and two reversed. then mount one prop and see which way it turns. If that is correct then using that as the guide you go ahead and mount the other three props. if you are having trouble visually identifying if the prop orientation is right you should check to see if the props are pushing air/blowing downwards or upwards.

So the prop direction is right if the air is going downwards.

@saintofinternet: your order would be shipped out today evening

May be you would get it by tomorrow evening.

ok so now i get it... its 1 & 3 either CW or CCW and 2 & 4 exactly opposite of earlier config....

@saintofinternet

You are right... With V939 FC, motor 1 & 3 require opposite soldering i.e White (from motor) to black (From connector) & Black (from motor) to Red (From connector).
Also motor 1 & 3 will always run CCW. Hence the opposite soldering.

motor 2 & 4 run CW hence solder Red to Red & Black to Black.

As @frankinsmoke mentioned, to check your prop direction, place the prop infront of you and see which side does the pitch rise. if it rises ( or is higher ) to the LEFT its CCW, if it rises to the RIGHT its CW   

Now this is frustrating....

I resoldered all wires and connected each motor to the  battery and checked the air flow. All were giving the air thrust downwards.... Then numbered them according to CW and CCW and placed them.

When i connect the FC V939 and bind with FS9THX the motors push the air upwards...

Also when connected to the battery the motors spin with very high thrust but when thru the FC their speed is much low not enough to get the lift. Anything yo do with the Radio Control? I am using FS 9THX.

N

If you set your throttle trim at 0 while binding (as recommended)  increase the trim to 100% and then turn on your Tx to arm the FC. This helped me when my quad wasn’t going higher than a foot.

Also scheck if your motors are at a 90 deg angle to the sticks and that they are aligned correctly.

Tx calibrations are important. Things like your  End Points settings & trims.

if the direction of the air flow is changing between battery and FC, then maybe the wiring between the motor and FC is incorrect… maybe??

Hey... Changed the design... Frame made from the sticks sent along with kit... Motor to motor distance 150 mm.....Pic attached. Reference: Satyabhai Zindabad!!! 

Now it is Frog....  .... It actually jumps and lifts itself a Max 2 cms from ground and highly unstable... All motors at 90 degree. Props rotation perfect.... Thrust from all 4 is downwards. It tends to roll more...

Any idea?  Also this is the first time i am doing this and also handling the transmitter first  time hence do we have any FS 9THX lessons on the internet?

try this...

@arun.sreelakam

Arun Sir... Still eagerly awaiting build video...

hey thanx for the video but unfortunately my firmware in the transmitter is completely different. i have the original FlySky firmware still in it so that video is of no use to me as of now...

Reiterating what has been said multiple times on this thread before...
This kit is pretty awesome and is a must buy for any beginner who wants to experience the pains and fun of DIY before foraying into full fledged modelling on your own.
The detailed build log by Siddaniels was pretty useful for my own build. Not many replied to him but thanks a lot man! It helped me a lot!

At first try, my build had issues of excessive wobbling right after lift off. But as expected, it was my own error with the motors not being at a perfect 90 degrees in all three geometric planes. With a little more trial and error corrections, i was able to make it fly perfectly balanced although i am a complete beginner to quads!
Thanks a lot Satya for making such a simple and cheap solution available to us! 

Just one query at the moment, how can i make the quad hover being  at least reasonably still. At present, it simply keeps floating away in any random direction if i try. Also, i am not able to keep it vertically still. It either keeps climbing or dropping. BTW my end points for all channels except throttle are at 75% if that info helps. Any guidance?

@ajayjohn

You are absolutely right sir... this is a great build, probably THE BEST around town and with the info provided here everyone can be a quad flyer.

Glad to know that the info was useful to somebody...

suggestions for your query. As stated earlier I think by Veloci optimal motor to motor distance is 100mm to 120mm. Smaller is better!! My Quad was 115mm ( in the video ) and i could get it to hover pretty steady for a while. After a serious crash i cut the M to M distance to 99mm. It tends to drift toward the rear so by giving continuous forward input (very little stick movement) i get it to hover steady for a a decent amount of time. The reduction in size has definitely increased steady hovering.

Also a stupid mistake i made was to set my EP as 75% - 75%. it should be 25% - 75%.

Thanks for the info Sid! 
My build's shaft length is 120mm and motor to motor distance would be about 4-6 mm less than that which seems to fall in Veloci's ideal range.
Still getting some amount of lateral movement

Could you please elaborate on your EP values?
As in (which ever applicable)...
Aileron: xx% - xx%
Elevator: xx% - xx%
Rudder: xx% - xx%
Throttle: xx% - xx%

I am assuming the rest are left at the default 100% - 100%

hey guys, i feel so happy that you guys are enjoying this built so much. I admit that its very hard to get it right in the first try. I myself have made 4 frames, all are not perfect in any sense

But all the problems that you might face is discussed in this thread and many are solved and suggestions are mentioned in this thread. And one very important thing that you guys need is patience a lot of patience.


Buddy i am not very sure, but both of your build pics that you have shared it seems to be me that V939 is not mounted in the center of the frame. It has to be at the dead center of the frame. And it affects a lot.

Glad to be of help Ajay...

Move your Tx sticks very slightly especially for Aileron and Elevator. try to find that prefect stick position that gets the quad steady.

My EP settings

Aileron: 25% - 75%
Elevator: 25% - 75%
Rudder: 25% - 75%
Throttle: 100% - 100%

I trim my throttle right up before arming the FC otherwise I don’t get a lot of lift. Haven’t figured that one out yet. I think it’s got to do with the throttle channel’s stick signal range. Maybe you won’t require it. If your quad is flying really high at full throttle then you probably don’t require resting the trim.

I’m using a Hobbyking T6A V2 Tx. I feel (I maybe wrong) that every tx will react differently to the FC so you’ll have to spend some time on it. I tried using the throttle curve on heli settings on my Tx and some really weird stuff started happening. So keeping it simple for now : )

Satya Sir… it’s because of people like you that we guys get a chance at a build like this… And we all must thank you for that! 

For everybody who’s new to this and has bought the DIY Kit, the thing to watch out for in a DO-IT-YOURSELF build is the “YOURSELF” part. So read as much as you can about it… the rest will come along the way. Happy flying...

Hi Guys,

I recently bought the DIY V939 mini quad parts from Quadkopters.com. I am building the frame at the moment. Guys i have a EFLITE HP6DSM 6-Channel 2.4GHz Transmitter, 2.4GHz DSM2 is it compatible with the V939 controller board?? When i connect the battery to the controller, the LED flashes fast and then goes OFF, When placed on a flat surface the LED flashes again fast and then after 3-4 secs it starts flashing slowly.. I tried binding this transmitter but the LED on V939 controller is not going SOLID RED.. i tried over and over still the same. Even if i dont turn on the transmitter the light sequence on the V939 remains the same fast flash and then slow flash.. is everything alright with the board or can someone help me binding sequence correcty...

I tried all this steps and it doesn't work :-

1. Plugin battery to receiver LED will flash quickly and stops
2. Keep it on flat surface and LED will start to flash again at a rapid rate
3. Hold bind button on your TX and switch it ON
4. LED on receiver should start to flash slowly
5. Turn off your TX and leave the bind button and switch ON your TX again.
6. LED on receiver should be solid now...

THE STEP SIX DOESNT WORK  NEED HELP !!

not with DSM2, compatible transmitters are listed on the first post and on the product description page.

oh no... why not DSM2 ?? i assumed it would work... i cant buy another transmitter now... is there any other way to make it work ??

Well the receiver that is on the V939 works with only the compatible transmitter listed.

I am also building a Q450 quadcopter. So the DSM2 transmitter is compatible with Orange Rx ?

finally i was able to lift the quad today after making a hell lot of different designs and was able to hover for 40 secs once.... but after that even with a full charge battery it refuses to leave the ground. don't know why and how. 

i want to know one thing how is that this props and motor generate only less than 40 grams of thrust? and how come the same config from the market can fly something heavier? i mean even adding a drop of hot glue messes the weight configuration and its like back to square one.   

now i have ordered the small motor holders from satya yesterday so hoping to recv. it today. let's see if that help me in keeping the motors straight at 90 degrees and also if they can be of aid for me to put on some extra weight... need to figure out something like adding an extra transmission gear of different ratio to change the RPM's etc... 

the kit is fabulous with unlimited potential to try out but i request satya to also add a "patience package" in his online store which one can buy to keep going  ;-) kidding....