Hello fellow flyers.

I have a problem with my drone. I noticed it a couple of weeks ago.

When I fly in a straight line, the aircraft starts pulling to the left after a couple of meters.
This is very disturbing if I'm flying where it's narrow with trees around, I can't trust it to go straight.

I fly with VPS turned off.
I have calibrated the compass, imu, rc many times.

Could it be that I haven't been on a completely flat surface while doing IMU calibration?
Could it be firmware related?

Has anyone else had this issue?

/Sam

Just a suggestion, was there any wind?  I found that my P3 will yaw left if there's a strong wind.

Don't fly it again till you recalibrate on a FLAT surface that a steel ball stays still on and calibrate the compass outside away from any metal objects including your phone and watch, then let us know what happens after.

off course it needs to be on a flat surface when you calibrate imu

There wasn't any wind yesterday and it still did it.

That's why I said completely flat surface.
It's not like I have had it super-tilted while doing the IMU calibration

But I haven't used a real spirit level to measure it. (I don't have one)
I downloaded a spirit level app on my phone and did the calibration on my kitchen table , but I don't know if you can trust the app at all.
I'll try to borrow a real one from a friend or neighbour and test it again.

I did not have this problem in the beginning, and I have always done the IMU calibration on the same table, that's what worries me.

You should be doing it on a level surface.  Proven to be level with the use of a leveling device.  I think the use of "flat surface" is the wrong terminology to be using.  As much as I would like the floors in my old house to be level and the flat surface of the table to be level, a lot of times they are not.  

Shutter Posted at 2015-8-20 00:33
There wasn't any wind yesterday and it still did it.

That's why I said completely flat surface.

If all calibrations have been done correctly, and this is only an un-educated shot…..how many hours on your bird? Have the props been damaged? Using a rpm meter check your motors, I have read that motors can have a window before complete failure, perhaps it is possible one is not producing the required torque. I'm probably way off base but perhaps someone can discredit my thoughts.

I did not get a hold of a spirit level tonight to do a proper imu calibration on a level surface. (I agree, level instead of flat)

However i changed all my props, and went to the local football field where i calibrated the compass, away from all things that
could possibly disturb it.

And it seems like it worked, it flew straight all evening.
Going to test it some more tomorrow.

Shutter Posted at 2015-8-20 03:05
I did not get a hold of a spirit level tonight to do a proper imu calibration on a level surface. (I ...

Glad you have it fixed! I hope it stay's that way.

I have an suggestion for everyone that don't have a spirit level. Any contained water surface is always perfectly level. You can't have it 'more' level than that.

Take a bowl, large in diameter, as larger as better, but not very tall. I took my wife's flan-pan for doing this. Place the bowl or whatever container in the center of the surface you want to do the leveling on. Fill it with water to a level where it just so not overflows the rim. Inspect the water level distance to the rim. it should be all around the exact same distance. If the water is beginning to go over the edge on one side but on the opposite side you see a distance from the water surface to the rim edge, then you need to adjust your surface until the water is exactly the distance from the rim edge all around.

I used a flat concrete slap and put bricks under each corner. Then I put pieces of plastic sheets between the bricks and the concrete slap until it was level. using a concrete slap also has the advantage that it doesn't matter if you spill some water. Oh yeah, I did that outside away from anything metallic. Make sure there is no reinforcement in the concrete slap. If in doubt, use a wooden board  :-)

When it's level, use it to calibrate your Phantom.  

Shutter Posted at 2015-8-20 03:05
I did not get a hold of a spirit level tonight to do a proper imu calibration on a level surface. (I ...

I had the same exact problem last weekend.  I kept thinking I was holding the stick the wrong way and maybe pushing slightly to the left each time.  Luckily, recalibrating the IMU worked for me too.

Apparently you got the NASCAR version of the Phantom 3!   :p

Shutter Posted at 2015-8-20 03:05
I did not get a hold of a spirit level tonight to do a proper imu calibration on a level surface. (I ...

glad it worked for you doing it on a flat level surface.

I did everything that everyone said and is still going to the left when I fly straight I tried new propellors calibrated on complete level surface many times

Hello,
RC calibration done ?

Shutter Posted at 2015-8-19 11:05
I did not get a hold of a spirit level tonight to do a proper imu calibration on a level surface. (I agree, level instead of flat)

However i changed all my props, and went to the local football field where i calibrated the compass, away from all things that

Another thing since you changed the props. The others might have been unbalanced.
Balance all of your props from now on before using them. I'm sure you will see a big difference and also might notice that your bird is also more quiet.

I think the name of the most popular prop balancer is called a DuBro. A friend of mine gave me one and it is funny when you see how even new props can be way out of balance.