A2 Test Flight Problems

[teecee]

So this is my very first build and it is a 950 Carboncore H6 with A2 flight controller, 2 X 6C batteries and Futaba T14SG TX. I have it all together, balanced and started testing today. Motors are all spinning correctly, props mounted right and mixer correct for my setup. The bench test went fine with the retractable landing gear strapped down. All directions were correct. First flight - not so good. It immediately flipped over backwards but no damage done (except pride). Then I called my dealer for advice. Turns out IMU was mounted backwards. My thinking was that the cord should come out the BACK like 99% of other items that plug in. Not! I should have noticed the compass was that same way... Remounted IMU, re calibrated compass and bench tested again. All seemed well. Tried another "tethered" flight test. Tied to heavy lead weight with about 2 inches of play to the strut centre between the rails. Figured I could see it get off the ground but not give it enough play in the tether to flip again. Second flight test started better but it was wobbly and then, sure enough, it tried to flip sideways but tether prevented it going over. Now I really don't know what it is. Gains? I don't have a clue what they should be and right now they are factory defaults. My overall weight is 5170 G or 11.4lbs.

Anyone out there have any ideas?

Thanks,

TC

 

[Carapau]

Can you get some photos of your rig and some screen shots of your assistant software?

 

[Bartman]

I understand that you said your props are turning in the correct direction but an instant flip over is usually going to be one or more prop turning in the wrong direction or your controls (one or more) are reversed.

Look in thee software at which direction the controls are moving as you move the sticks and make sure the sticks (left/right, forward/backward) correspond to what the FC is seeing. you might have to reverse channels if things are backwards.

remove props before doing this as moving the controls may cause the motors to spin up

bart

 

[teecee]

Can you get some photos of your rig and some screen shots of your assistant software?

Here you go...View attachment 15606View attachment 15607View attachment 15608View attachment 15609View attachment 15610

 

[teecee]

I understand that you said your props are turning in the correct direction but an instant flip over is usually going to be one or more prop turning in the wrong direction or your controls (one or more) are reversed.

Look in thee software at which direction the controls are moving as you move the sticks and make sure the sticks (left/right, forward/backward) correspond to what the FC is seeing. you might have to reverse channels if things are backwards.

remove props before doing this as moving the controls may cause the motors to spin up

bart

I have the mixer right and all props spinning in the direction of the arrows with leading edge high and each prop opposite to the one next to it. I suppose channels could be backwards. When I move Aileron the marker on the main screen in A2 software moves the opposite direction and for elevator when I move the stick UP marker goes RIGHT and Stick DOWN = LEFT. Perhaps there is something there...

 

[teecee]

Setup Pic

Forgot this pic though it does not show how I have the 2 6C batteries mounted. I have one centre rear on the battery mount and a second front centre on the DJI battery plate that came with the retracts. It is pretty balanced. This setup is temporary until I finish tests and get gimbal on there.

View attachment 15611

 

[Bartman]

i don't know how the A2 interface is but with the NAZA when you mouse over the channel displays there's a pop-up that specifies which way the sliders are supposed to move when you move the sticks.

good luck with it and welcome to the site.
bart

 

[teecee]

i don't know how the A2 interface is but with the NAZA when you mouse over the channel displays there's a pop-up that specifies which way the sliders are supposed to move when you move the sticks.

good luck with it and welcome to the site.
bart

Hum.. No mouse "tool tips" here in A2 land.

 

[Carapau]

Your props look as though they are the wrong way round. Looking at your photo the boom at the front right of the photo is the front prop, judging by how your GPS is pointed. Prop number 1 should be spinning anti-clockwise- or at least is should be in the WKM and I am guessing the A2 is the same. Just check in the A2 manual or assistant software, which way prop number 1 should be spinning. Also you haven't put in any vertical distances for the IMU and GPS positions. Gains look to be fine to start with although will need tuning to get the best flight performance.

Given your first error with the IMU and with the props I would just take a pause, go through the A2 manual very slowly and triple check everything.

 

[teecee]

A more recent pic.
View attachment 15612

 

[teecee]

Your props look as though they are the wrong way round. Looking at your photo the boom at the front right of the photo is the front prop, judging by how your GPS is pointed. Prop number 1 should be spinning anti-clockwise- or at least is should be in the WKM and I am guessing the A2 is the same. Just check in the A2 manual or assistant software, which way prop number 1 should be spinning.

Ha, you are correct sir. My mistake as that photo was taken the other day BEFORE I looked more closely at the arrows in the mixer. I since changed all the prop directions and switched the props physically. The last photo reflects this change and is how I was configured during my flight tests today.

 

[teecee]

What about gains. Is there any reason for me to suspect those?

 

[Carapau]

Gains look fine for starters- they won't have caused the flip.

Make sure you get the IMU and GPS figures for their mounting correct. I don't think this will have caused the flip but it won't help

Have you balanced your props? Vibration could easily cause a flip.

 

[Jumpy07]

I would also check your IMU mounting configuration in Assistant and make sure the orientation is correct.

 

[teecee]

Gains look fine for starters- they won't have caused the flip.

Make sure you get the IMU and GPS figures for their mounting correct. I don't think this will have caused the flip but it won't help

Have you balanced your props? Vibration could easily cause a flip.

The GPS is mounted with the arrow (and cord) mounted towards the front. The IMU was backwards (I think) but I reversed it so that the cord faces forwards which I think it the standard "forward" configuration. I have set it to the first check box in the "mounting" window. Looking at it this morning I see the GPS and IMU X,Y,Z offset boxes. I had left all those at the default "0". Perhaps that is my problem. X and Y should be good because both are center, center but Z... How do I determine vertical center of gravity? I'll bet this is it.

 

[Carapau]

The Z figure wont cause a flip but it wont help either. In order to ascertain the center of gravity, hold the copter by 1 motor and let it dangle. Drop an imaginary plumb line from the motor and where it intersects the X/Y CoG is where the vertical CoG is. Then just measure from that point up to the center of the IMU and GPS. This figures can only be changed in increments of 1cm so absolute accuracy is not a problem.

 

[Tahoe Ed]

I hang mine from a door frame by a motor and then draw a line to see where it intersects the Z axis.

 

[teecee]

You are right, that didn't help. First test this morning and it tipped over the other way (left). Dinged one prop a little but it was on a large foam pad so no real damage. There is just no stability and it kind of shakes back and forth as the motors speed up. Something is totally off here and I have no idea what it is. Very frustrating!

Thanks for all the help so far though. I really appreciate it. I know I've seen this comment before but "these things really DON'T just build themselves". It is fun building and troubleshooting but I really am just ready to see this bird fly.

 

[Bartman]

teecee, do you have any other RC experience? that's a lot of scratch invested in that helicopter and it would be a shame to see it go to waste in the process of learning to fly it.

if the IMU was backwards is it possible the wires are all backwards now that you've flipped the IMU to be oriented correctly?

 

[teecee]

teecee, do you have any other RC experience? that's a lot of scratch invested in that helicopter and it would be a shame to see it go to waste in the process of learning to fly it.

if the IMU was backwards is it possible the wires are all backwards now that you've flipped the IMU to be oriented correctly?

I have been flying the Phantom and AeroSim a lot since the middle of the summer. I am pretty good with those. I realize this is a whole new beast but...
Which wires?