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?

Sorry Robert missed you weathervane comment, Your right thats how the old rate gyros worked which was good if you were flying fast forward, as you say the tail would in the end line up. But i believe most people have learnt to fly by feeding in tail as well as aileron. But would it possible to have a switch, to go from Rate to HH? just like most gyros do. 

Yeah, I was thinking it could be a Ch7 option.  

I think it would be a feature that scale guys would like.  Or even just sport fliers.

We've got an issue describing something very close to what you're describing.  In this suggestion it's an extensino to simple mode so that if you command the roll or pitch to be over x degrees it turns to point in the direction you're commanding.

Hmmm...  Ok, so people are interested.

I think that it would be better if it was related to air (or ground) speed, rather than bank angle.  Basically, make it fly like an airplane.

I think it should also be "soft".  Not like, if you're hovering, and then start moving, all the sudden it crosses a speed threshold and *boing* it spins around.  I'm thinking a speed deadband of 10km/h.  Once you pass 10km/h, it starts acting, but it's variable.  Always subtract 10km/h from the airspeed, so with a speed of 11km/h, it's acting with a "force" of 1.  At 20 km/h, force of 10, etc.  The turn rate would look something like:

If (velocity > 10km/h && WeatherVane)


WeathervaneTurnRate = ProportionalGain * (heading direction - velocity direction) * (airspeed - 10km/h)


And I would just add that TurnRate right into the same equation where pilot yaw commands affect the heading.

YawRate = YawIn + WeathervaneTurnRate

That way, the pilot could still input yaw, but it would always be countered by the strength of the weathervane.  So you could only "skid" the tail out, but the amount that you could skid would depend on airspeed (this would fall out of the equation naturally, not require a new equation).  

So, end result is, if you are hovering, and then start flying sideways, once you pass 10km/h, it will softly start to weathervane into the direction of movement.  The faster you go, the faster it turns around.

The Proportional gain could be established with a default that people don't *need* to touch, but could touch if they really wanted.  Ideally, it should be overdamped so that it never oscillates past the straight-back.  This will be helped by the fact that the weathervane yaw rate is influenced not just by speed, but also by the angle error.  So for a given speed, the turn rate will be reduced as it approaches straight-back.  

If you fly the copter around a corner, the yaw heading will naturally lag a little.  A little bit like adverse-yaw in an airplane.  So, the pilot would still be required to "lead" the tail around the turn with the rudder if they want to make a really nice turn, just like an airplane.

The idea springs out of the fact that I can fly airplanes really well.  But I'm still learning helis.  Part of the problem is, as they say, too many degrees of freedom.  This somewhat removes one of those degrees.

This would allow a pilot to put it in Alt_Hold for example, Weathervane on, and fly really nice circuits just like an airplane.

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.

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?


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