3.0.1 - 2 Questions - Discussions

Decided to finally switch over from 2.9.1 to 3.0.1. I have been doing some testing on a lazy susan before taking it airborn and have 2 questions.

1. wp yaw behavior. 5 was the default and that appears to make the heli not care which way it faces. I was testing RTL and my failsafe and the swash moved in the proper direction but my yaw did not change. I then changed the value to 1 and now the heli rotates towards the home location and the swash looks good. Can anyone give me a description of wp yaw behavior 1 - 5.

2. Loiter PID's. 3.0.1 does not have NAV parameters only LOITER. In 2.9.1 my Loiter numbers were D=.05, I= .3, P=4 and nav was D=0, I=.17, P= 2.65. I was looking at Sean's parameters for 3.0 from back in July and his Loiter #'s were closer to my old nav numbers. Would my 2.9.1 nav numbers be a decent starting point for tuning 3.0.1 loiter numbers.

I have spinblades ( head and tail ) arriving tomorrow and hope to fly and tune this weekend.

Regards.

David Boulanger

I could also use anyones spinblade knowledge. I have a TREX550. Just put a 10 tooth pinion on it and think it will still be overgeared a bit with the 1220KV motor. I have optical tach I will use to adjust the headspeed and I guess I will hook up a amp meter to see what I am drawing. I don't know how low of a motor speed I can run and stay out of trouble. Thanx.

1. There actually is no WP Yaw Behaviour number 5. It's not a mode, so I'm not sure why you have that number, did it come in as a default? So what is happening is you are getting a Default behaviour which is Yaw Hold. It will just stay where it is.

WP Yaw #1, is Look at Next Waypoint. So at the instant when a new waypoint is targetted, it will turn to point at it. But I believe it won't update the yaw as the course changes, I believe it stays locked.

WP Yaw #2 is the same as #1, unless you are doing an RTL, in which case it will hold whatever it's last yaw was.

WP Yaw #3 is Yaw Look Ahead. This automatically yaws the heli to look straight ahead in the direction of travel, constantly. This should be the default for Helis as it makes the most sense.

2. I suggest just to use the default parameters. You should be able to see these on the first post of Randy's 3.0.1 announcement post. The numbers seem to work very well for all helis, big and small, and even multicopters. This is because the control loops are set up so well, with a physical model of the world, they work regardless of the aircraft. If anything, you might try softening the Loiter P from 1.0, to 0.8, just to make it a little less "busy". But you have to be careful with this as it can cause the system to not settle at a waypoint.

As far as Spinblades, I have done some investigation with them, but not a good scientific study yet. What I have found so far is that they won't return any efficiency benefit if you are turning them at full speed. Flight time is the same. You have to run them much slower. I was flying a 550 stretched to 700, and it weighed 16lbs AUW. It flew at 1200 rpm, but 1400 rpm was a little more comfortable. Not nearly as much punch as 1800, but very adequate for a UAV application. 1200 started to get to the point where you needed to be careful about "settling under power" and having trouble breaking out of the vortex during a descent. You must fly very scale-like. But at these kinds of speeds, I was getting 25 minute flights, using two battery packs which it had no trouble lifting.

From what I can see, these return the best performance if you load the helicopter up with batteries. If you try to do some kind of ultra-light-weight machine in the search for flight time, it just doesn't work out well for Helis. I think they will work better with extra batteries, and as much rotor speed as needed to lift them. Obviously there's a limit somewhere. But double typical battery capacity seems like a good starting point.

Replies

Rob_Lefebvre November 9, 2013 at 12:19pm

1. There actually is no WP Yaw Behaviour number 5. It's not a mode, so I'm not sure why you have that number, did it come in as a default? So what is happening is you are getting a Default behaviour which is Yaw Hold. It will just stay where it is.

WP Yaw #1, is Look at Next Waypoint. So at the instant when a new waypoint is targetted, it will turn to point at it. But I believe it won't update the yaw as the course changes, I believe it stays locked.

WP Yaw #2 is the same as #1, unless you are doing an RTL, in which case it will hold whatever it's last yaw was.

WP Yaw #3 is Yaw Look Ahead. This automatically yaws the heli to look straight ahead in the direction of travel, constantly. This should be the default for Helis as it makes the most sense.

2. I suggest just to use the default parameters. You should be able to see these on the first post of Randy's 3.0.1 announcement post. The numbers seem to work very well for all helis, big and small, and even multicopters. This is because the control loops are set up so well, with a physical model of the world, they work regardless of the aircraft. If anything, you might try softening the Loiter P from 1.0, to 0.8, just to make it a little less "busy". But you have to be careful with this as it can cause the system to not settle at a waypoint.

As far as Spinblades, I have done some investigation with them, but not a good scientific study yet. What I have found so far is that they won't return any efficiency benefit if you are turning them at full speed. Flight time is the same. You have to run them much slower. I was flying a 550 stretched to 700, and it weighed 16lbs AUW. It flew at 1200 rpm, but 1400 rpm was a little more comfortable. Not nearly as much punch as 1800, but very adequate for a UAV application. 1200 started to get to the point where you needed to be careful about "settling under power" and having trouble breaking out of the vortex during a descent. You must fly very scale-like. But at these kinds of speeds, I was getting 25 minute flights, using two battery packs which it had no trouble lifting.

From what I can see, these return the best performance if you load the helicopter up with batteries. If you try to do some kind of ultra-light-weight machine in the search for flight time, it just doesn't work out well for Helis. I think they will work better with extra batteries, and as much rotor speed as needed to lift them. Obviously there's a limit somewhere. But double typical battery capacity seems like a good starting point.

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