I've been working on the ArduPlane code for the new APM2 boards for a while now, so I was delighted to watch it loitering above my local flying field today for the first time. I'd flown it once before two weeks ago, but that was a very short flight as I had the aileron controls reversed (I don't have much experience with elevon planes!), so it was quite tricky to steer. It 'landed' in a tree that time. I also had no telemetry for that flight as we hadn't yet worked out the MUX switching needed for the telemetry UART in the APM2.

Pat and I fixed the MUX switching problem last weekend, so this weekend was my first chance to fly APM2 with a ground station and full telemetry. The weekend started off with an interesting problem. I took it out to the field yesterday and got it ready to fly, then waited for GPS lock. It takes a while to get GPS lock in Canberra, so I was waiting a few minutes. As soon as it got GPS locked I was surprised when the ground station reported that the board was rebooting! Time to take it back home for more bench testing.

added a patch that faked up GPS lock after a specified period of time, which allowed me to reproduce the bug on my bench, and after a couple of hours of false starts I finally found and fixed the bug this morning. Time to flight test it!

Since I'd last flown my SkyFun (with an APM1 board) I had replaced the hinges, put in a bigger motor and a new ESC, so I was expecting the tuning to be a bit off. It sure was! I only switched to manual once in the flight and it dived hard - it looks like my CoG is a bit off with the new setup. I did the rest of the flight with the APM2 stabiliser enabled, letting the code take care of the trim. It's easy to get lazy with trim when you have an autopilot :-)

I did two flights today, of about 10 minutes each. It can probably fly for 20 minutes or more, but I don't have a current sensor fitted, so I didn't want to push it. In both flights I did a few minutes of LOITER, which is a good test that everything is working well in the code, as it needs all the sensors and logic to be working to keep it going around in circles in one place.

As you can see, the LOITER went perfectly, despite quite a strong wind and poor tuning.

The APM2 really is a great board, and the smaller size makes it perfect for little foam planes. I also like the fact that the inputs and outputs are at opposite ends of the board, making wiring neater.

Of course, best of all, the APM2 can fly!

Views: 3538

Comment by Andrew Tridgell on December 3, 2011 at 5:48pm

You can see some closer up photos of the APM2 board fitted to the SkyFun here:


Comment by Max Levine on December 3, 2011 at 6:22pm

NICE !!!

And as always you kill bugs in seconds :)

Comment by Martin Poller on December 4, 2011 at 2:21am

The APM2 board looks great, very neat installation.

Can you tell me how you've set up the multiple Li-pos please, are they simply just joined together in parallel or have you used a particular connection board. Thanks

Comment by UnmannedTechShop.co.uk on December 4, 2011 at 3:12am

Looks really good, when you say windy, how strong was it?  But still that is an impressive loiter circle considering you have not tuned anything!  We are looking forward to testing the APMv2 in some smaller models that APMv1 did not fit in neatly.


Comment by Simon Wunderlin on December 4, 2011 at 3:26am

Great news!

@tridge: a warning to all delta plane setups: I haven't had time to fly my funjet lately. But there was (is?) a bug in the code which will reverse elevator in FBW-B (FBW-A used to work as expecte) with a delta wing setup.

Due to time constrains (i am going back to scool for studing EE) I haven't had time to investigte the code, so I am not sure if this problem still exists. I am also unsure if it happens with all setups. I am using an MPX 3030 RC transmitter.



Comment by Sandro Benigno on December 4, 2011 at 4:00am

Wow... Great job Tridge! (not on the trimming... LOL)
"It's easy to get lazy with trim when you have an autopilot" <-- indeed


Comment by Andrew Tridgell on December 4, 2011 at 4:26am

@Martin, I just have the two 1.3Ah 3S LiPos in parallel. The reason I did it like this is I measured the peak current with my new motor and ESC at 60A, which would be well above what any of my 3S LiPos could handle. With two in parallel its fine. If you want to try parallel LiPos just make sure the voltage on the two of them is roughly equal before you connect them. I usually check they are within 0.1V, although that is pretty conservative.

Comment by Andrew Tridgell on December 4, 2011 at 4:28am

@UT, it was probably 15km/h or so, but varied a bit during the flight.

@Simon, thanks for the top, I'll have a look at the elevon code when I have some time.

Comment by Martint BuildYourOwnDrone.co.uk on December 4, 2011 at 5:10am

@ Andrew, that looks fantastic! I can't wait to see and get my hands on the new APM 2.0!  It seems so small sitting in the plane, can I ask why you had installed it where you have?


@ Martin, I dont't know what battery connectors you use, but these y connectors are very good at joining two batteries together :)







Comment by Sandro Benigno on December 4, 2011 at 5:47am

@Tridge: is that motor the Turnigy 2836-2350?
I love the twins battery solution! I will copy you on that. =)


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