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Old Feb 07, 2012, 07:46 PM
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eflyingman's Avatar
USA, CA, Orinda
Joined Nov 2005
265 Posts
Thank you, spainman!

That video really helped me figure a few things out. For one, it is not at battery connection time that the gyro selects its level position, but at throttle up.

Second, it seems to me that the times I have a better time flying this heli, it is when I have heading hold off, which on my transmitter is as little as two clicks.

Now, how do I trim it so that the tail doesn't drift AND having heading hold off? If I trim with two clicks, then the heli yaws in that direction.

With heading hold on, if I am in forward flight and turn, the swash resets, but if I counter the resetting too soon, then the gyro seems to have found a new level position, different than my previous hover. Is that the experience of others too?

Lastly, has anyone noticed erratic tail motor performance, or is that due to the heading hold being off?
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Old Feb 07, 2012, 08:06 PM
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United States, MO, Columbia
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Quote:
Originally Posted by Martyn McKinney View Post
JUST AN UPDATE TO ALL OF YOU WHO HAVE REPORTED DIFFERENT HELI BEHAVIOUR THAN I HAVE BEEN OBSERVING AND A BELATED APOLOGY IF I HAVE DISAGREED OR APPEARED TO BE SHOUTING.
Next round of liquor is on you
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Old Feb 07, 2012, 08:31 PM
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Any solution to the drift issue yet? Don't flame me ok, I don't have time to read all posts, subscribed.
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Old Feb 07, 2012, 09:40 PM
jbb
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This is a good case for U to be a HH customer support rep

Lol

Quote:
Originally Posted by Chuckster2 View Post
I don't completely understand but I believe it has to do with trim settings.
If the rudder trim disagrees with what the software senses is actually happening then a signal is sent to the servo to correct, if the servo correction does not doesn't jive with what the board is sensing from the gyros a feedback loop will cause the reciever to keep attempting to complete the command until the next cyclic input, resulting in the wrong correction as it attempts to catch up.
I got the impression from the article that trim of any kind could cause erroneous signals, was not to be used and let the gyros do their thing.
Apparently these feedback loops are the quirk that needs be dealt with with this type system?
The guys who seem to be having the most success with these things are the guys that are fiddling with them the least.
But that may be misperception.
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Old Feb 07, 2012, 10:10 PM
jbb
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Old Feb 07, 2012, 10:23 PM
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So do I use rudder trim or not? Or is this heli just a faulty product?
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Old Feb 08, 2012, 12:12 AM
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United States, MO, Columbia
Joined Dec 2011
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Quote:
Originally Posted by X_ColonelAngus_X View Post
So do I use rudder trim or not? Or is this heli just a faulty product?
Get air born and in a decent hover
Then let go of the cyclic stick
Next apply 3 clicks of rudder trim
See which way the bird drifts off
Adjust the links to prevent sudden drift when the rudder is applied.

Whether its faulty or not is up for debate and a matter of opinion.
It does make it harder to fly with the current software...but people are doing it.

The bird does have good qualities however..its quick ,fairly tough, takes the wind good for its size and is very indoor friendly as far as crash damage to bird and house belongings
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Old Feb 08, 2012, 12:39 AM
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United States, MO, Columbia
Joined Dec 2011
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Quote:
Originally Posted by eflyingman View Post
That video really helped me figure a few things out. For one, it is not at battery connection time that the gyro selects its level position, but at throttle up.

Second, it seems to me that the times I have a better time flying this heli, it is when I have heading hold off, which on my transmitter is as little as two clicks.

Now, how do I trim it so that the tail doesn't drift AND having heading hold off? If I trim with two clicks, then the heli yaws in that direction.

With heading hold on, if I am in forward flight and turn, the swash resets, but if I counter the resetting too soon, then the gyro seems to have found a new level position, different than my previous hover. Is that the experience of others too?

Lastly, has anyone noticed erratic tail motor performance, or is that due to the heading hold being off?
When you release the rudder the attitude of the bird is the new attitude.
As far as being able to prevent yaw with 2 clicks of rudder...no way to fix that..but if you are in the house doing maneuvers..you will be moving the rudder all the time anyway.

I use to fly a little with rudder trim on all the time...but after i got the links pretty close to a hands off hover{with rudder trim applied}.. I can end up with what is similar to TBE while in a hover and is very hard to get ahead of to stop it.
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Old Feb 08, 2012, 12:53 AM
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United Kingdom, Oxted
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Quote:
Originally Posted by Chuckster2 View Post
Does it require trimming?
No, I didn't touch either. They both were pretty good at hover from the start. The first one did an extremely slow yaw but it flew fine and stayed straight on FF.

Since then, the tail rotor blade lost its 'grip' so I changed it - that's all I've done.
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Old Feb 08, 2012, 04:50 AM
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Aachen, Germany
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Quote:
Originally Posted by New Toys View Post
Thanks for the video spainman..I almost thought I was going nuts here
One question though.
If I set a few playing cards under the front of my skids and hit nothing but the throttle...the swash will ease up a little {taking several seconds} as if the bird knew it wasnt level.

Sure there isnt something on the boards that is a reference point to level?
Yes - absolutely sure. There is only an itg3205 3 axis mems gyro on board. Pretty nice device btw.

Cheers,
Ruben
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Old Feb 08, 2012, 05:46 AM
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Aachen, Germany
Joined Jun 2007
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Quote:
Originally Posted by eflyingman View Post
Now, how do I trim it so that the tail doesn't drift AND having heading hold off? If I trim with two clicks, then the heli yaws in that direction.
Well, actually you can't!

Even the slightest trim on the rudder will induce yaw drift. The initial perception that the three clicks of rudder trim on the stock transmitter that enter rate mode on the cyclic are zeroed out on throttle up is simply wrong. I had the same impression but the three clicks of trim are considered.

The thing is that the amount of rudder trim needed to kick in the rate mode is so small that it is pretty much unnoticable in flight. On the stock transmitter the three clicks result in a drift of round about 0.5-1 per second.

It can be observed by holding the heli motionless in the hand with only the tail motor connected. Throttle up without rudder trim and the tail rotor will run at nearly constant rpm just varying a little to compensate for slightest movements of the hand.

Do the same with some clicks of left rudder trim and the tail will start to slow down over time till it stops. That's the heading hold loop slowing down the tail to achieve a more and more ccw moving reference angle.

When using another transmitter you can possibly adjust the amount of trim that is caused by one click. Set it as low as possible and move the trim till rate mode is enabled, then you have found the minimum drift possible while having rate mode enabled.

But I wouldn't recommend to fly in rate mode, the heli feels much bigger on the sticks in attitude hold mode and if the linkages are perfectly adjusted you will not feel too much of the mode switching on rudder input.

Just use the rate mode to adjust the linkages to a nice hands off hovering like you would do on a ordinary physical flybared heli and go back to zero rudder trim for normal flying. Actually it is the same procedure as setting up a hh tail gyro - mechanical setup in rate mode till drift is minimized as much as possible and then switching to hh mode.

Cheers,
Ruben
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Old Feb 08, 2012, 06:10 AM
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Romania, TM, Timisoara
Joined Aug 2011
125 Posts
Rudder trim (as any other trim) is interpreted as constant input (rudder input in our case). We know on rudder the swash is sent to the 0 position, so it's perfectly normal what happens when you use rudder trim.

That's why rudder trim seems to work and the gyro seems to switch modes.

Seems like while rudder applied, there is a mix between "send the rudder slowly to 0" and "execute cyclic commands".

This is not clear enough for everybody: any in-flight trim changes are equivalent to holding that stick off-center.

To further simplify things: while rudder is applied we have no stabilisation whatsoever, the swash goes to 0 unless we give cyclic. Like flying a flybarred heli without the flybar. Even the cyclic commands are no longer permanent, the second you release cyclic the flybar will go again towards 0 position.
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Old Feb 08, 2012, 06:28 AM
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Aachen, Germany
Joined Jun 2007
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Quote:
Originally Posted by danb1974 View Post
To further simplify things: while rudder is applied we have no stabilisation whatsoever, the swash goes to 0 unless we give cyclic. Like flying a flybarred heli without the flybar
That is a little bit oversimplified and not the case - sure there is stabilisation when rudder is applied. It's just a different kind of stabilisation that just dampens undesired roll instead of moving the heli back to the original attitude - on tail gyros it is simply called rate mode.

Cheers,
Ruben
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Old Feb 08, 2012, 11:07 AM
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bladecpfreek's Avatar
USA, WI, Almena
Joined Aug 2008
545 Posts
Hey guys. Just a quick question. What's the difference between the rate mode and heading lock mode for the servos? I fly my mSR x hard and have pretty much adapted to the yaw problem.
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Old Feb 08, 2012, 02:28 PM
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United States, MO, Columbia
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Quote:
Originally Posted by bladecpfreek View Post
Hey guys. Just a quick question. What's the difference between the rate mode and heading lock mode for the servos? I fly my mSR x hard and have pretty much adapted to the yaw problem.
When the rudder is applied the servos centers
While the rudder is on we have more of a rate mode..if you move the stick for say right aileron..the servo will move..but will come back when you let go of the stick.
When the rudder is off and you move lets say the stick for right aileron then release the stick...the bird will keep that position and the swash will change accordingly to keep the heli body in that position, until you move the stick to cancel that last command of right aileron....Non rate mode
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