[GAntonjo]

Not being as “reckless” as you Terje, I have so far not had too many crashes. My flying has mostly been to learn to operate the tricopter at slow speed at an abandoned (due to winter) football field. The most expensive I have broken is the back CF boom from David when I lost orientation of my tricopter and crashed into a bench at the mentioned football field.
Apart from this I have of course broken “a ton” of zipties.

[GAntonjo]

Fredrik: As I told you, the heading shown when the motors are not running is correct for the internal compass, but when I start flying the heading turns opposite of the real heading. After reading up a little on the theory of electronic compasses, I have come to the conclusion that the power cables run directly under the HKPilot Mega cause a lot of interference when starting the motors.

I have now connected the Ublox Neo7 compass again and disabled the internal compass. I have run a successful compass calibration in my living room and the tricopter now shows south when pointing south. Furthermore, the heading does not change when tilting the tricopter forward. I may have messed up the declination setting earlier, so with correct declination settings the compass behaves well so far.

I will have to wait some day to get a flu out of my body before I can verify that this change has been successful.

Freakazoid: Last time I did an AutoTune on my ArduCopter 3.1.5 it totally failed. It started off by tilting and yawing very hard straight after takeoff. I only got a meter or so up in the air and managed to land without any damages. After this the tilt and pitch was completely off level when putting the tricopter on a level surface. I had connect the PC and run an accelerometer calibration to make it fly again. I am not sure what cause the AutoTune to fails so badly – maybe my failing compass caused this. I look forward to try my latest changes a day in the near future.

[GAntonjo]

Thanks, Terje.

I guess my “day pass” in Copenhagen won’t allow me more than a walk in the city and a beer or two with my friends;-)

By the way, I hope your friends and family were not close to the shooting that happened today:-( Take care.

[GAntonjo]

Ok, so I return to this thread.

Since I moved my HkPilot Mega 2.7 from my wooden frame to the nice carbon V3 frame, I have not been happy with the compass of the FC. When using the external compass, the heading changes when tilting the tricopter, so I have disabled the external compass. After a successful compass calibration of the internal compass, the heading is pretty correct when turning the tricopter by hands. However, when I start flying things change. I use DroidPlanner on my Galaxy S5 to view the status of my tricopter. After a minute in the air the heading changes so that it shows the tricopter pointing towards east when it actually is pointing towards west. This of course is messing up the GPS enabled modes of the HkPilot. I am not able to use PosHold, Loiter or any other mode that rely on correct GPS and Compass data.

I noticed that when I land an disarm, the heading again is correctly shown, but as soon as I take off the heading slowly goes completely off real heading.

I brought my laptop to the flying field today and executed a CompassMot calibration to see if this helped. CompassMot showed 645% (!!) interference at 100% throttle. Anyway, after running the CompassMot calibration the situation did not improve.

To be sure the problem was not caused by ArduCopter FW, I have even downgraded from ArduCopter v3.2 to v3.1.5 and reset all parameters to factory default. This has not helped, and actually the tail of my tricopter seems more nervous with v3.1.5 than with v3.2 FW. I will probably upgrade to v3.2 again in near future.

As for the compass problem, I’m tempted to move all electronics back to my wooden frame to see if problem is caused by the carbon booms. It would be nice to hear from you Mippen if you see similar problem with your APM?

[GAntonjo]

Ok, this gives all the answers;-)

Look at https://www.youtube.com/watch?v=QrL9rgncUmg#t=115 where they explain how to connect the KK Mini to the REceiver. Looking at your pictures, I am pretty sure that you have the receiver wrongly connected. First of all, your receiver has signal at bottom pins in your picture “receiver-graupner-gr-12.jpg”, meaning you should move the cables on ports 1,2,4 and 5 to the bottom pins of the receiver. Furthermore, you should turn the first cable on the “kk2-mini.jpg” picture so that order is Brown, Red, Yellow. Normal use of the colors are:

Brown (or black) : Ground (-)
Red : +5v (+)
Yellow (or white): Signal (S)

[GAntonjo]

I guess the amount of torque depends. I run the DT750 motors with 11×4.7 carbon props secured with nylon lock nuts. When I tried Auto Tune on my HKPilot 2.7 (APM clone), the torque induced by the rapid change of directions caused the lock nuts to unlock twice before I realized the reason. So – it is indeed possible for the torque to loosen the lock nuts 😮 Now I use Locktite, especially on the front right prop.

Another solution would be to use self tightening rotation direction on all props. On the tricopter this is doable (at least with the APM) since the tail tilt mechanism will be able to adjust for any yaw caused by all props rotating the same direction.

[GAntonjo]

Sorry for your loss, Crass 🙁

I guess it will be easier for the forum members to help you if you upload some close up pictures of all your connections as they were at the time of frying your KK2 board. I cannot promise any help as I fly the HKPilot Mega 2.7 flight controller instead of the KK2. I am however sure the other ones in here will be able to help. Good luck, I really hope you get it sorted out.

[GAntonjo]

Terje.

I am not an aerodynamics engineer, but I give it a try.

I took your winter foot and analyzed it a little. Given that the outer diameter is 5 cm and each ring and connection between the rings are 0.55 cm wide, I come to the total area of 11.81 cm squared touching the ground. If we then count for the width of the top of the leg and estimating it to 1.65 cm, we could make skis that are 7.2 cm long and 1.65 cm wide and get the same area touching the ground. Ok, let say we let the skis point in the same direction as the booms, I believe this will cause negligible effect on the drag, maybe even less drag. BUT – this for sure would look strange :-p

However, if you twist the two front legs +/-120 degrees so the sides of the legs are parallel to the tail boom, you should see less aerodynamic drag at straight flights than with the landing gear you have created. In addition, by “correctly” rounding of the top of the skis I would guess the drag under the propellers should be less than with the round feet. If I had the 3D modelling tools and skills you have, I would definitely give this a try;-)

[GAntonjo]

Hehe, Terje. Of course everything can land on powder snow – being able to float on top of the powder is however another problem :-p

I saw your video before my previous comment, hence the idea of skis. Furthermore, just the visual look of a Tricopter with winter skis pointing forwards (twintip?) I believe would look nice, but maybe not more practical than the rings you created. Have you calculated the area these rings give, compared to rectangular skis of same weight or strength?

[GAntonjo]

Terje, since you are flying in the Nordic snow, wouldn’t it be nice with some skis on your tricopter? You obviously have both the tools and skills to create some 3D printed skis that face forward on all booms;-) Of course not all touchdowns will be with forward/backward movement, but even so a set of skis could help avoiding hooking too hard to the ground.

[GAntonjo]

Terje, I know that feeling when the tri “decides to go hunting men” by itself. Yesterday when I was flying with a couple of friends with their 2 quads and a hexa, I had a similar experience. At the end of my second battery I was flying some not too fast turns. Suddenly my tri accelerated by itself and took off towards one of my friends and crashed into the snow close to him (I have never seen him run that fast). At the same time the tri “went hunting” the battery alarm sounded, and my answer to the sudden loss of control lays in this. My ArduCopter is configured to land for battery fail safe. Being in the middle of a turn, less than 3 meters above ground, this fail safe function obviously failed:-(

Result of crash, only a set of cheap strips needed to be replaced;-) Took my tri to another 2 flights today, but decided to land at 40% left on the batteries, which gave me 15 minutes per battery.

[GAntonjo]

Finally the weather became OK for getting some air under the tricopter. Today I went to a snow covered football field with 2 friends and I must say I was satisfied with the way my tricopter flew today. Here you have my PID settings. To be honest, I don’t remember whether I managed to get a full auto tune run before new year, so which parameters are changed from stock I don’t remember.

My tricopter with HKPilot Mega 2.7, GPS and Telemetry radio weighs in at 1.95 kg ready to fly. As posted in another thread, I use the DT750 motor with 11×4.7 carbon props. Why so heavy, some one asks. Well, I guess the canopy, 550g 4S 5000mAh battery, extra landing gear, LED strips and a Raspberry Pi with camera module and 2600mAh battery all adds nicely to the weight :-p

Anyway, it felt pretty nice. Not like a sports car, but more like a momentum strong family sedan:-p Perfect for learning to fly.

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[GAntonjo]

Good morning, RCJim.

I cannot tell if you safely can run your LEDs directly on 4S. It all depends on the voltage tolerance of your LEDs. The LED strips I use on my tricopter are for 12V, but I have successfully connected them directly on my 4S LiPo (no switch). One solution would be to connect them to the balance plug of your LiPo, only using “3S”. Look at this Balance Connectors description to get an idea on how to use the Balance plug for tapping less than 4S off the battery. Between any 2 adjacent wires on the balance plug you should get 1S voltage (i.e. 3.7V).

IMPORTANT NOTE: If you choose to connect the LEDs to the balance plug, you will un-balance the battery charge. This should be OK for a low-current load as the LEDs, but if you use this for loads that draw more current, you may damage your LiPo. In any case, use a LiPo alarm that can check all LiPo Cells individually and alert if they fall below the 3.0V on any cell.

I would also add a fuse on the cables to the LEDs to be on the safe side.

[GAntonjo]

(Slightly Off-topic)
I look forward to seeing Terje do something like this with his weather proofed tricopter 😀

[GAntonjo]

David!

Thank you very much for the top tilt mechanisms you added to my order of replacement arms. Not a big value money wise, but a great customer care value;-)

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