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Old Feb 07, 2012, 01:51 AM
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United States, MO, Columbia
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If it couldn't determine level..then how are you holding it exactly the same way in your hand at each hand launch?...wouldnt it shoot off if the "level" was determined when the throttle was opened?..and your hand wasnt perfectly level?

You can basically just toss it out there and hit the throttle and start to fly if you want..so it must know board position IMO
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Old Feb 07, 2012, 01:52 AM
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Toronto Canada
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But you just stated that when you added 6 to 8 swash link turns to the right, the swash went to the right and stayed to the right (after a temporary gyro correction) after you had tilted it to the right.

Are you telling me that your heli will hover with 6 to 8 swash link turns to the right?

Now, I'm really begging you to fly it in this condition with centered transmitter trims and report back what happens.

Why has this been so difficult?

Quote:
Originally Posted by New Toys View Post
so it must know board position IMO
It doesn't know board position. You can initialize it upside down and sideways and the swash will still initialize to its idle position.

Any self levelling is likely due to the pendulum effect because most of the mass of the heli is below the thrust axis.

Trust me, there is no way that your heli will self level with 6 to 8 aileron swash link turns added.

There has been a similar argument on the MQX quadcopter thread. The MQX also uses the AS3X system. There is NO self leveling from the gyros. Any minor self levellng is due to the pendulum effect.

On the MQX, applying any significant short term input from the sticks will make the quadcopter go on in that direction forever. When flying my MSRX outdoors, it behaves in the same manner.
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Old Feb 07, 2012, 02:00 AM
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Quote:
Originally Posted by Martyn McKinney View Post
But you just stated that when you added 6 to 8 swash link turns to the right, the swash stayed to the right after you had tilted it to the right.

Are you telling me that your heli will hover with 6 to 8 swash link turns to the right?

Now, I'm really begging you to fly it in this condition with centered transmitter trims and report back what happens.

Why has this been so difficult?
6 to 8 lol..I dont even think they will go that far
My swash is right and forward now.
It has been level..it has been back..it has been all over the place within 3 turns and it will hover.

And yes when I added trim with the transmitter the swash went to the right full travel...until I tipped right then it came back some then went full right again.
But remember I dont use transmitter trim in flight I keep them at zero.

You dont use transmitter trim on these birds as it is a command...the servo will keep going..just as if you held the right stick a little
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Old Feb 07, 2012, 02:03 AM
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How about this
I think you have a three turn recommendation out on one of the links..yes?..Might be someone else though
So according to your argument if they had a bird that hovered and turned the link three turns it wont hover?
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Old Feb 07, 2012, 02:10 AM
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Quote:
Originally Posted by Martyn McKinney View Post
But you just stated that when you added 6 to 8 swash link turns to the right, the swash went to the right and stayed to the right (after a temporary gyro correction) after you had tilted it to the right.

Are you telling me that your heli will hover with 6 to 8 swash link turns to the right?

Now, I'm really begging you to fly it in this condition with centered transmitter trims and report back what happens.

Why has this been so difficult?

It doesn't know board position. You can initialize it upside down and sideways and the swash will still initialize to its idle position.

Any self levelling is likely due to the pendulum effect because most of the mass of the heli is below the thrust axis.

There has been a similar argument on the MQX quadcopter thread. The MQX also uses the AS3X system. There is NO self levelling from the gyros. Any minor self levelling is due to the pendulum effect.

On the MQX applying any significant input from the sticks will make the quadcopter go on in that direction forever.
Quote:
But you just stated that when you added 6 to 8 swash link turns to the right,
Those were transmitter clicks not turns of the link
Quote:
Are you telling me that your heli will hover with 6 to 8 swash link turns to the right?
I havent tried it nor am I going to..but I do know if you within three turns hovering is not a problem
Quote:
Now, I'm really begging you to fly it in this condition with centered transmitter trims and report back what happens.
As said my links have been in 3 turns of opposite directions..it hovers the same without touching transmitter trims...there is no need to go 6 or 8
Quote:
It doesn't know board position. You can initialize it upside down and sideways and the swash will still initialize to its idle position.
And when you launch from your hand crooked and use only throttle the bird will settle into a hover.....so what is it using for reference?
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Old Feb 07, 2012, 02:13 AM
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Quote:
Originally Posted by New Toys View Post
So according to your argument if they had a bird that hovered and turned the link three turns it wont hover?
If it hovered handsoff before adding 3 link turns, my experience is that it will not hover handsoff after adding 3 link turns.
Quote:
Originally Posted by New Toys View Post
And when you launch from your hand crooked and use only throttle the bird will settle into a hover.....so what is it using for reference?
Pendulum effect with the short term assistance of the rate gyros which are correcting for any angular motion of the heli.

There is no doubt that there is some self-leveling occurring. I can almost put my transmitter on the ground, go out and grab a coffee and the heli will still be in the same position, but other than the rate gyros detecting instantaneous changes, this has nothing to do with electronic level sensing.
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Old Feb 07, 2012, 02:18 AM
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Quote:
Originally Posted by Martyn McKinney View Post
If it hovered handsoff before adding 3 link turns, my experience is that it will not hover handsoff after adding 3 link turns.
I dont know why..it has to be from using transmitter trim.

Does your swash follow the bird when you move it around in your hand when you have it throttled up a little?
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Old Feb 07, 2012, 02:30 AM
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Originally Posted by New Toys View Post
I dont know why..it has to be from using transmitter trim.
I really don't understand this statement!

My heli hovered hands off with centered transmitter trims.

I increase the aileron swash link length by 3 turns so that my swash is tilted to the right.

I leave the transmitter trims at center.

HOW CAN THE HELI STILL HOVER HANDS OFF WITH THE SWASH TILTED TO THE RIGHT?

Quote:
Originally Posted by New Toys View Post
Does your swash follow the bird when you move it around in your hand when you have it throttled up a little?
The swash behaves like it is being controlled by a rate gyro.

If I hold the heli level, the swash is roughly level.

If I then quickly tilt the heli forward, the swash will try and compensate in the opposite direction while the heli moving. As soon as the heli stops moving, even though it is tilted forward, the swash will return to the previous level condition (WITH RESPECT TO THE AXIS OF THE HELI WHICH IS NOW TILTED FORWARD).

This is characteristic rate gyro behaviour. If there is no angular motion of the heli, there is no gyro output.
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Old Feb 07, 2012, 02:42 AM
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As the swash moves according to the position of the board
Do this
Center all trims
Hold heli in hand tipped forward.
Move the throttle and only the throttle.
The swash will move as the heli isnt level.
Granted it isnt as fast....Because an input hasnt been given yet...but the bird will still try to level itself out..so therefore it has a reference point of level.
If the links are off we can see it doesnt matter...a link being off would cause the bird to tilt..but it will tilt itself back anyway...


But none of this really matters anyway/ even if it didnt / because the bird will remember its last input when you get it into hover and keep it until you give another command...unless you have transmitter trims off of zero..then the bird will keep going that way
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Old Feb 07, 2012, 02:53 AM
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but anyway i need to get to bed
All I know is the bird always drifts to the right a little I have had my links tuned a fair amount in all directions..but the bird always settles to a slow right drift.
Talk to you tomorrow Martyn
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Old Feb 07, 2012, 02:54 AM
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Quote:
Originally Posted by New Toys View Post
Move the throttle and only the throttle.
The swash will move as the heli isnt level.
If the heli has been properly set up and the hover position is the same as the zero throttle position, advancing the throttle will not make the swash move because advancing the throttle moves the swash from its servo center position to the hover position. The gyros in the heli have no idea what at what attitude the heli is positioned.

Properly set up, both of the swash positions are the same and the orientation of the heli is a non-factor.
Quote:
Originally Posted by New Toys View Post
so it must know board position IMO
If it knew the board position, the transmitter trims wouldn't work because the gyros would always be trying to make the board level regardless of the transmitter trim position.

This does not happen. The gyros are rate gyros and sense angular motion only.
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Old Feb 07, 2012, 03:40 AM
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Wow... so much confusion.

Actually the way the fbl system works is really simple:

- The fbl system does not know it's absolute attitude (perfectly normal for the usual fbl systems - it simply does not matter in any way)

- The fbl system just detects any rotation offsets (actually it detects rotation over time and integrates it to an amount of rotation) on any of the three axis and counter acts them till the offset is zero

- Inputs from the pilot basically (there is more than just that but for the current discussion it doesn't matter) just set a new reference attitude and the fbl system will do what ever is needed to attain and hold that new reference attitude

That means that
- Cyclic trim is a no go -> it is interpreted as an constant command to change the current attitude at a small rate of rotation over time. The only reason to use cyclic trim is that the potentiometers on the transmitter might be off zero. As soon as you add cyclic trim you will destroy the ability of the fbl system to hold a certain attitude constantly without pilot intervention. Off course you might not even notice it because hands off hovering is only a matter of seconds till you do the next correction...

- Changes to the linkages don't affect anything but the known flaw where the swash plate moves to the current stick+trim position (yes, it is not the zero position where it moves to)

- Changes to the linkages will not change anything about hands off hovering. It will just change the amount of initial corrections the pilot has to do in order to get the bird into its hands off hover attitude. Remember - the fbl just detects uncommanded rotation on any of the three axis and counteracts it till the previous reference attitude is reached. As long as there is enough servo movement available the linkages can be ANYWHERE. Simply doesn't matter in normal flight. Just matters on take off and when applying rudder (the flaw thing...).

@MM:
1.5ms is not an alternative term for position zero - this is dsm2 and on board servos, there are no ppm pulses anywhere and zero ppm pulse was different on some radio brands anyway... no I'm not an smart-ass but seeing it repeated over and over mantra like I thought I should mention it. What's the point of saying "1.5ms" instead of zero anyway?

Cheers,
Ruben

PS: Some video showing what I'm talking about
http://www.youtube.com/watch?v=EjhiWlKdu9w
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Last edited by spainman; Feb 08, 2012 at 11:39 AM.
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Old Feb 07, 2012, 04:41 AM
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spainman is right in his description of the fbl system. I would only add that infinite hands-free hover is not possible because small gyro errors/inaccuracies accumulate with each reading and the fbl has no way to notice that. Probably the genius cp is much better (probably best noticed in wind) at that in 6-axis mode because is also has accelerometers who detect movements even if there are no attitude changes. Those would also exhibit cumulated errors, so if you really want a hands free hover you need a camera-pointed-to-ground correction system.
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Old Feb 07, 2012, 05:18 AM
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Quote:
Originally Posted by Martyn McKinney View Post
The swash behaves like it is being controlled by a rate gyro.

If I hold the heli level, the swash is roughly level.

If I then quickly tilt the heli forward, the swash will try and compensate in the opposite direction while the heli moving. As soon as the heli stops moving, even though it is tilted forward, the swash will return to the previous level condition (WITH RESPECT TO THE AXIS OF THE HELI WHICH IS NOW TILTED FORWARD).

This is characteristic rate gyro behaviour. If there is no angular motion of the heli, there is no gyro output.
Obviously what you are describing is the behavior when rudder is applied or the rudder trim is off zero.

If that is the way you are flying it then you should check your rudder trim and alter it till you get an attitude hold behavior during your in hand testing.

Cheers,
Ruben
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Old Feb 07, 2012, 05:31 AM
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I like spainman's explanation.
This guy seems to know what he is talking about as well:
http://www.rchelicopterfun.com/blade-msr-x.html
kinda saying the same thing.
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