Level and Center of gravity - basics - Discussions

OK, I have been trying for a while now to get the basics working but seems to be unable to get it right, I guess I am not the only one struggling with this so some sort of detailed instructions will be helpful.

First of all. I have the quad copter set up for x-frame, tested all functions work ok, and it is kind of flyable in stabilize, but it behaves far from stable, I have tried loiter with almost catastrophic outcome, but I guess the advanced modes have to wait until it flies ok in stabilize first.

So what are the problems :

When taking off into hover it tends to go forward and right, after I stabilize it into hover with stick input, it looks ok, but releasing the sticks make the copter advance forward and also quite fast to the right.

I guess this has to to do with leveling and Center of gravity, and possibly ensuring that the frame is not "out of true", but how do I go about checking these parameters? I have leveled the copter on the floor, which I guess is "level", I have tried to lift the copter by the dome and the COG seems ok, I have eye-spotted the frame and motors and they all seem to be quite ok. What else can you do, or are there some tricks to go about fixing this? Or is there something wrong with the electronics in my copter? Any ideas? BTW running 2.049 for the moment.

It's the propellers that have to be level. It doesn't matter if the APM, frame, or anything else is level, only the props - after all, it's the props that generate thrust.

There are two ways to set level in the field, which is potentially better than setting level in mission planner, especially if APM is physically plugged into the computer (when you remove the plug, you will inevitably move the APM, which will affects it's relationship with the props).

The first way is to hold disarm for 10 seconds (hold yaw all the way to the left). This will just 'reset' the level in APM to the current position of the copter. Obviously, this is only a good way to set level if the propellers are perfectly level.

The second way is to hold arm for 20 seconds (hold yaw all the way to the right). This will engage the in-flight leveling procedure, which should last 45 seconds (although on my copter, it only lasts 13). When in-flight leveling is engaged, the roll and pitch stick doesn't just fly the helicopter, but adjusts the level setting based on your stick. Thus, if your copter is drifting forward and to the right, when you pull back and to the left on the stick, the level setting should slowly adjust to account for that movement such that eventually you'll be able to let go of the stick and the copter won't drift. Once the copter is stable, land it, wait out the rest of the 45 seconds (leds blink in a special way when in-flight leveling is engaged), and then disarm the copter (yaw left for 2 seconds) to save the new 'level' to APM. That's it!

BTW - very important; don't try to use in-flight leveling except in an absolutely windless environment! Also, fly the copter at least 4 feet off the ground to minimize ground effects.

Hope that helps. Let us know if any of that isn't perfectly clear.

Hope that helps.

Replies

Todd Steury November 1, 2011 at 5:43am

It's the propellers that have to be level. It doesn't matter if the APM, frame, or anything else is level, only the props - after all, it's the props that generate thrust.

There are two ways to set level in the field, which is potentially better than setting level in mission planner, especially if APM is physically plugged into the computer (when you remove the plug, you will inevitably move the APM, which will affects it's relationship with the props).

The first way is to hold disarm for 10 seconds (hold yaw all the way to the left). This will just 'reset' the level in APM to the current position of the copter. Obviously, this is only a good way to set level if the propellers are perfectly level.

The second way is to hold arm for 20 seconds (hold yaw all the way to the right). This will engage the in-flight leveling procedure, which should last 45 seconds (although on my copter, it only lasts 13). When in-flight leveling is engaged, the roll and pitch stick doesn't just fly the helicopter, but adjusts the level setting based on your stick. Thus, if your copter is drifting forward and to the right, when you pull back and to the left on the stick, the level setting should slowly adjust to account for that movement such that eventually you'll be able to let go of the stick and the copter won't drift. Once the copter is stable, land it, wait out the rest of the 45 seconds (leds blink in a special way when in-flight leveling is engaged), and then disarm the copter (yaw left for 2 seconds) to save the new 'level' to APM. That's it!

BTW - very important; don't try to use in-flight leveling except in an absolutely windless environment! Also, fly the copter at least 4 feet off the ground to minimize ground effects.

Hope that helps. Let us know if any of that isn't perfectly clear.

Hope that helps.

This reply was deleted.