I have just bought the ArduPilot Mega 2560 Full Kit... plus the Triple Axis Magnetometer HMC5883L. I should have it built over the weekend.. then i'm off to a my mates machine shop, and i'll make the splitter plate for the lower frame onto which i am going to fit the Ardupilot. the magnetometer i'll put on the tail as suggested. I am going to use my X-cell Razor 600E. For those that dont know its around the 50 size nitro heli.

Do i need to buy any other sensors i.e. the Sonar... i can fly a helicopter all day long but this is my first time flying one with stabilisation so any tips would be gratefully appreciated.

If this works well then i am going to try and use it on my x-cell gasser. i can get up to 20 minute flights with this. But i think for the time being a battery 600 is the way to go.

i'll post some pictures when i have it all together.



Setup Instructions

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Yes, sorry about that.  Known issue, I thought it would be fixed, but it's not.

You can still setup with CLI, or put your parameters into the parameter screen manually.

No problem, it's that I don't have my parameter file with me atm, and I'm having problems setting up tail without external gyro with a decent servo (picked up a specturm yesterday)

My  Rate P 0.4 value I used couple of days ago is way to touchy now, or my stab yaw P is off, either way it's a hand full today :(

Despite the rain, I managed to fly. Two things:

- The GPS not found issue must have to do with a sometimes very slow booting function of the ACM. Sometimes the ACM needs quite a while until green and red lights starts flashing. I have no clue why, but it is clearly the reason why then the GPS can not be recognized.

- How big should the Alt Hold or Loiter D terms be? I know from other PID loops, that D terms are often about 10x larger than P term. So I am wondering why they are set up 10 or even 100 times lower than P term. Will I freak the PID loop up by really strongly increasing the D terms for Alt hold and loiter?

Uh, yeah, you don't want to have the D terms too high, very bad.  D terms are a double edged sword for PID tuning.  They can really help polish a process.  But they can also really mess it up really fast.

Had another two good flights today, with 2.5+.  Really fun.  Did a bit of Loiter, but I still don't have it tuned in yet.  But it didn't do anything stupid.

One idea I had was to create a "weathervane" function.  I think this would help when just flying the helicopter around.  It would act similar to the way old non-HH would weathervane.  Heading hold is nice in some cases, but not others.

It would be selectable.

Basically, it would have a speed deadband where it doesn't do anything.  Above this deadband, it would have a P-I function which would turn the nose of the heli into the direction of the velocity.  The higher the speed, the stronger it would try to turn to face it.  This might help make the helicopter fly more like an airplane.  You would be able to yaw against it with the sticks, but probably only so far.  

It would make nice scale-like flying easier.

What do you guys think?  Would it be nice, or a waste of time?

Noob question time: Does the forum have an option to search a single thread? I'd like to search this thread to see if my quuestion has already been answered, but 117 pages is too much for me. My eyes glazed over at about page 25.

If you'll forgive my short attention span and complete nubbishness, I'm hoping for a little insight to get up to speed. This is my first ArduPilot, and for that matter, my first R/C. I'm putting this together as a project for my undergraduate engineering studies, and finding a love for the hobby in general, even though I'm still a complete noob. I've been relying on my friends who are experienced with R/C to get me up to speed on that end, but I'm still inexperienced with the APM.

I am just a little confused about mounting my new APM 2.0 on my TRex 450 Pro V2. I've got it mounted on the radio tray behind the swashplate on top, but I saw Randy say in an older thread that the GPS needs to be out from under the rotor to get signal.

Does this mean the GPS needs to be all the way back on the tail, or just out from underneath the main metal stuff? I bought my APM 2.0 with the integrated GPS, and I'm hoping I didn't screw up super bad in the process.


Hmmm... That's a tough question.  I can't really say if that will be OK or not.  Conventional wisdom is to put it on the tail, but I don't know it's every been proven to be *necessary*.  I have put my compass on the APM, and it is proving to be troublesome.  I plan on moving it.  I don't know 100% that it's the cause of the problem, but I've run out of patience fighting it and don't have the tools to try and get the data I need.

We should probably update the wiki page to point out that people want the APM2 without the GPS and compass on it.  Those should be purchased separately and put on the tail...although I agree with Robert, it's not been proven that it matters if it's under the blades.


When it comes to mounting the main APM itself, I think putting it between the body and the landing gear is the best place.

Is your APM mounted under the body or on the radio tray? If it's under the body, conventional wisdom says the motor will bother the megnetometer. The reason I'm mounting my APM 2.0 on the radio tray is because I thought that it would be the best place for both the megnetometer and the GPS.

I'll run a long test when I get it up and running completely. I'll spin up the blades and keep it on the ground for a few minutes at different angles.

If the GPS stays solid, I'll know it'll probably be ok. If not, one of my fellow students still has his APM 2.0 on back order for his quad, so he'll be able to change his order to external GPS, and we'll trade across.

Actually, come to mention it, if I just order the external GPS module, will the APM give me the option to lock out the onboard one, or will I actually have to get one without onboard?

I've got a 600, and it mounted under the tail, just behind the frame on a custom subframe.

I don't think the GPS has to be fully out from under the blades.  We've never seen that to a problem, but we have seen motor magnetics cause problems for the compass.

Why do you prefer mounting underneath? I've read some of the older conversations on the topic, and things to consider, and I gave it some thought.

There were a couple of reasons I decided on using the radio tray. If I'm not understanding right, please set me straight. I'm certainly not married to any of my justifications here.

The first is that flying the stock setup, I had the gyro mounted directly under the rotor shaft in a little space in the body, and a trusted friend said that that spot tends to suffer from vibrations messing with the gyro. I figured similar mounting for the APM might do the same.

The second is for the aforementioned placement of the onboard mag and GPS, getting away from the motor, and putting the least stuff possible above it without using external GPS. That reason may be invalidated if my GPS tends to drop out where it is.

The third was for weight distribution. While radio tray placement normally makes it back heavy, I'm also strongly considering getting a nice little camera and gimble, and mounting it on the front of the copter, a bit like the electronics pod on the nose of an AH-64 Apache. I figured if it looked cool enough, I'd even get an Apache body kit and go the whole 9 yards. XD

 I figured it would be iffy mounted underneath because it was so close, but I thought the radio tray might be far enough. Do you know if anyone has had problems with it mounted on the tray?

If not, then then the same question applies for the mag. Will I need to replace the APM with one that doesn't have onboard mag, or can I use an external mag and have the software bypass the onboard?

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