Quad Can't Take Off

G'day everyone

I have just resurrected a home built quad that I bought off a young fellow a month or so back. It is a home build from Aussie Stuarts build a FPV racing drone for $99. I can't get the little beastie off the ground.

It has the basic components he recommended, but I replaced the F1 board with an F3. Being very new to the quad copter world, I have spent quite a bit of time messing around learning how to set up betaflight and BL heli (massive learning curve). The original software was cleanflight which I have overwritten.

Now to my problem:
I have set up the arming to have the motors idling. When I apply throttle, three motors spin up evenly, but one lags slightly. The result is props hit dirt before I can lift off or hover due to the imbalance. I can get the drone to a point where three motors are off the ground, but one still lags tilting the craft. I have tried to take off using a bit of pitch and roll compensation, but it just over corrects and props hit ground once again. I have also tried rapid throttle increase which just cartwheels the drone.
I have held the drone on the ground and fired up the engines then checked changes in motor speeds when applying pitch, roll and yaw. To my inexperienced eye, they all seem to alter speeds in relation to my applying the different stick controls.


Can someone offer me some direction in how I may adjust the engines speed so they are all synchronized and power up evenly please?

Cheers

Grant
 

D.O.G.

Goblin 380 Supporter
I would first check the motor to make sure it isn't bad. Then I would check the soldered joint from the motor to the ESC then the esc to the PDB to make sure there's no bad connections. You should be able to synchronized the motors in BL Heli Configurator. Just my 2 cents :).
 

Tony

Staff member
There are only 4 things that can affect just one motor. 1. you don't have that one motor properly setup in your FC. You will verify this in your MOTORS tab of BF. 2. the ESC is bad or has a cold solder joint as D.O.G. stated. 3. you have bad motor or cold solder joint. and 4. you have your prop on backwards or the wrong prop on that motor. Refer to BF for the correct rotation. We have all put props on backwards lol.
 
Thanks guys
I will check the solder joints.
The motor seemed to spin up evenly with the others using Betaflight.
How do you tell if a motor is bad or not outside of Betaflight?

cheers

Grant
 

Tony

Staff member
9 times out of 10, the motor will either work or it won't.

Have you checked the rotation to make sure it is going the correct way?
 
G'day Tony
I just checked and the props are going the right way.
Haven't had a chance to check the soldered joints yet.
Will post an update when I have checked them with the results.
cheers
Grant
 
G'day again Tony
I have not gone through all the solder joints as yet, but think I have found the problem.
When I spin the motors up with the computer and monitoring with Betaflight, they spin up evenly.
When I use the transmitter they are all over the place. Motors 1 and 4 spin up to 2000 and the 2 and 3 motors spin up all over the place. Slowly for a start then might jump to 2000 then drop back to low revs and so on.
My next questions now are: is this a software problem, a gimbal problem or something else?? Any help in isolating this problem will be appreciated once again.

cheers

Grant
 
Just had another play. This time the motors spin irregularly with all spinning at different speeds. If the throttle is held full on for a while they all get to max revs most times, but some still drop off. At no stage do they all spin at the same speed. The yaw control is either nothing or flat out depending on how it it feels at the time as well.
The pitch and roll motor speeds seem much more consistent, spinning up and down fairly evenly.

cheers
Grant
 

D.O.G.

Goblin 380 Supporter
Sounds like the motors aren't synchronized yet or solder joints bad. To synchronized the motors you need to plug the quad into computer or laptop, no battery yet. In betaflight, go to the motor tab. Make sure your props are off please. Go to where it said motor test and arming notice and enable that little box. Once you do that, go to the where it said master ans slide that all the way up. You should see all 4 motor slider be all yellow. Once that is completed, PROPS ARE OFF, then plug the battery into your quad. You should hear a musical sound. When that sound is complete, take the master slider and slide that down alll the way. It will do another musical sound. That should get your motors synchronized. If your motor aren't working properly after all that then check the solder joints. If solder joints are fine then you must go into BLHeli configurator and check youe ESC refresh rates. I hope this might help.
 

Tony

Staff member
TLDR but I did skim over it. What Tx are you using? Have you checked the monitor menu to see what the sticks are doing?

If it were me, I would start from step 1 and work my way through the setup again.
 
G'day Guys
Thanks for your help.
D.O.G. I have run through the motor process with Betaflight. It was here that I found that the discrepancy was when I spun the motors up with the transmitter throttle while I had everything connected to Betaflight.
Tony I will go through the full setup process again and see what happens from there. Will keep you posted, probably with more questions knowing my form lol.

cheers
Grant
 

Tony

Staff member
One thing to remember about spooling the quad up with the Tx is that it is trying to stay level. So unless the quad is perfectly level to where you calibrated it to level, it is going to change the motor inputs to achieve what it thinks is level. If it doesn't go to the level that it was calibrated to, it can turn motors completely off to try and achieve what it thinks is level. Just FYI.
 
G'day again
Tony, I have reloaded the software in the quad and firmware in the transmitter (transmitter is a Flysky FS-ia6). The latest firmware I could find was 15 Jan 2015. I am guessing there are newer firmware updates but I could not locate them. I am new to github and struggle to find my way around it search wise. I set up the switches as: SWA to arm at about 1100rpm, SWC (a dual switch) for angle and horizon.
After reloading the software, the computer throttle once again spins the motors up evenly and holds what ever revs are selected. I still have the irregular motor speeds when using the transmitter though.
When I arm the transmitter, the motors spin up at all different speeds. This can be anywhere from 1100 to 2000rpm. They won't settle back to an idle. When I apply throttle the speed increase is all over the place and won't hold maximum speed. They just speed up and drop off at random.
I set up all the controls with the quad on my desk which is quite level. I would have expected the motors to run pretty evenly even if they were compensating for being very slightly out of level.
I am totally baffled by the results.
cheers
Grant
 

D.O.G.

Goblin 380 Supporter
You mention in the beginning Grant that you bought the quad off a young gentlemen. Dumb question here but are all 4 motors the same and are all 4 ESC the same? How about a video showing us whats going on. Tony is real good at noticing what might be the problem by sound or visual characteristic response of the quad. Try to included in the video a screen shot what's happening on betaflight with your computer or laptop. This could help out tremendously too. Just a thought.
 

Stambo

Well-Known Member
Turn off self level modes while testing, this will eliminate any chance of it trying to vary motor speeds to attain level while testing.
If motor speeds are consistent in motors tab and throttle is smooth in receiver tab it is a most likely a flight controller issue.
Is the flight controller oriented the right way on the quad, there is an arrow that should point forward, otherwise the FC should be told which way it is rotated and by how much.
Are the motors hooked to the right outputs on the FC, IE when you speed up motor 1 in the motors tab is it the correct motor according to the setup diagram.
Video as suggested may help.
 
Thanks Guys
I will be off work on Wednesday in two days time so will video the quad and the Betaflight screen then and post it.
The four motors are the same. The esc is a 4 in 1 20A Racerstar.
I have not checked that the individual motors spinning up are the correct ones so will check that. I thought I reset the gyro. It seems to react as it should when I move it around.
I changed the yaw aspect by 90 degrees because the FC arrow is to the side.
I will look at the self level aspect and make sure it is off when I spin it up.
Should keep me quiet for a little while lol.
cheers
Grant
 

Tony

Staff member
Issues like these are hard to diagnose over the internet, but I love the challenge. Awaiting the video in hopes that we can see something.
 
G'day everyone
I have finally managed to get some video clips (9 of them) to demonstrate my problem, but the files are too large to load. Can anyone tell me how to modify the files to upload them please? I have them as Mp4 files at the moment and the largest is 49659 bytes.

cheers
Grant
 
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