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Old Nov 15, 2012, 07:49 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
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Also, I'm not defending the $30 gyro, I know that when you get a flybarless heli, the last thing you want is for it to fly like a flybar does.
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Old Nov 16, 2012, 03:38 AM
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Letchworth, Great Britain (UK)
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Originally Posted by Gedexas View Post
... when you get a flybarless heli, the last thing you want is for it to fly like a flybar does.
For me, that's exactly what I do want

I got my first flybarless at the beginning of this year, a 3Gx in a T-Rex 550e, and had no luck with it. I once managed a very wobbly hover for about 15 seconds, but the other four flights I couldn't even get off the ground without toppling over. I swapped the 3Gx unit for a micro Beast and had instant success on default factory settings. My only issue is that control with the micro Beast seems less "direct" than with my flybarred T-Rex 500. I've increased a couple of parameters to improve response, but even with quicker response it's still not as sharp as the flybar -- maybe that's a feature of all flybarless units.
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Old Nov 16, 2012, 10:09 AM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
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Originally Posted by abenn View Post
For me, that's exactly what I do want

I got my first flybarless at the beginning of this year, a 3Gx in a T-Rex 550e, and had no luck with it. I once managed a very wobbly hover for about 15 seconds, but the other four flights I couldn't even get off the ground without toppling over. I swapped the 3Gx unit for a micro Beast and had instant success on default factory settings. My only issue is that control with the micro Beast seems less "direct" than with my flybarred T-Rex 500. I've increased a couple of parameters to improve response, but even with quicker response it's still not as sharp as the flybar -- maybe that's a feature of all flybarless units.
If you want that flybarred feel, adjust the "hiller decay" variable. I don't know what it is called in the BeastX settings, but that's what other gyros call it.

My problem with the cx3x1000 is that the hiller decay is not adjustable, so the swash returns to level when you center the cyclic stick, which is what makes it so susceptible to outside forces, just like the flybar is.
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Old Nov 16, 2012, 12:03 PM
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Thanks, Gedexas. I don't have my Beast manual to hand at the moment, but "hiller decay" is not something I remember reading in it. IIRC, it has cyclic sentitivity and another responsiveness settings, which possibly amount to the same thing.

But, susceptibility to outside forces is not the kind of difference I'm noticing -- it's just that the flybarless seems to be not quite so directly connected to the trannie so, for instance, when I give a bit of opposite aileron it continues in its original direction for a fraction of a second before it starts moving the direction I've commanded. I've still got a lot of learning to do, and will probably try out a few more changes to the settings in the coming weeks.
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Old Nov 16, 2012, 05:20 PM
CP heli ≠ 3D heli
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United States, NJ, Point Pleasant Beach
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What you're describing sounds like a poorly setup flybar with too heavy paddles and too short flybar, that sluggish feeling that a flybar has, can be simulated in any FBL controller, as far as I can tell. When I first got my 450PRO, the first thing I did was to get rid of the sluggishness, not something I need when cutting grass.

I would start by increasing D and decreasing I in your PID settings to achieve that sluggishness. I also found something called "acceleration" and "deceleration" in the advanced cyclic settings of my cx3x1000. When the deceleration parameter is reduced, the cyclic does not stop immediately. I think that setting was originally meant to prevent cyclic stop bounce.

What I'm looking for is a rotor disk that "teleports" to where the sticks tell it to go and then does not move from there unless I want to, I was able to *almost* get my flybar to do it, but it is only a flybar. Hopefully the Robird unit gets me a helicopter that does something like that.
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Old Nov 17, 2012, 03:04 AM
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Originally Posted by Gedexas View Post
What you're describing sounds like a poorly setup flybar with too heavy paddles and too short flybar, that sluggish feeling that a flybar has, can be simulated in any FBL controller, as far as I can tell. When I first got my 450PRO, the first thing I did was to get rid of the sluggishness, not something I need when cutting grass. ...
Either you've mis-read me, Gedexas, or I'm misunderstanding you: My flybarred heli feels well connected to the trannie -- it responds instantly to control inputs without anything that I'd describe as sluggishness. It's my Micro Beast that seems to be slightly disconnected but, as I said, I'm still a learner on it so I've got plenty of adjustments to play with still.
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Old Nov 17, 2012, 08:57 AM
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There is no such adjustment in the Microbeast, we don't have access to the entire PID, and anyway, the PID part is not really for stick feeling.

If your Microbeast is still on version 2, uppgrade it to V3 for a much better direct feel control and better tail holding.

Pot 2 on the unit is there for cyclic stick control, increase it if you want more direct feeling, and Parameter ''G'' you can increase for an even more direct feeling.

You also need to set control behavior in ''transmitter mode'', because all of the default presets are very slugish, even the ''extreme'' is slugish.

Then at last, you need to have sufficient head speed on your model.
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Old Nov 17, 2012, 10:41 AM
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Haralson County GA. USA
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It seems to me that some fail to relaize that A FBL unit which cost around $70 today is much the same as one which would have cost $200 plus a year ago. Some also seem to forget that setting up and tweaking a FBL unit is a lot like tweaking a FB head. The FBL unit is tweaked with software while the FB head is tweaked with different length FBs,different paddle sizes,shapes weights, FB weights etc.

I find it simplier to tweak software settin than to do physical changes and it is also much faster and easier to rebuild a FBL head than a FB one , less parts ,less measuring ,balancing etc.

Best guide I have found on tweaking a FBL unit

http://downloads.hobbico.com/misc/tt...ary-wright.pdf

I have two Tarot ZYXs ,one in a Trex 450 with a Align DFC head and one in a Blade 400 with a Tarot non DFC head. To me the heads make major a difference in the way they fly . The DFC head sets lower and is more responsive. I also have a Copter X 3X100 in a Blade 450 with a Blade 450X head . All three can be tweaked to fly much the same or greatly different. Bottom line there is alot more variableables involved than just the FBL unit. All three of mine FBL units cost under $70 and they all work well with no issues and I would never go back to FB even thoust I have three FB heads and many replace parts for them.

If money was not an issue then I would purchase a HeliCommand 3XS which is most likely the very best FBL unit available and has the most dependable Rescue mode of them all.


For clarification... Many FBL units are capable of opering with a Satelite receiver only . This reduces the total cost,makes wiring simplier and saves some weight. Some support two Satelites thus provide true multi path reception same as a full receiver plus a satelite would when CF and aluinum shadowing would be an issue.

Charles
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Old Nov 17, 2012, 11:00 AM
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RoBird G31
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Old Nov 17, 2012, 11:22 AM
Southern Pride
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Haralson County GA. USA
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Any chance that unit is made by MSH which also just happens to make severl other FBL units such as the Ikon and the XBeast?

http://www.google.com/url?sa=t&rct=j...FnR0IYNCwWUUVw

Not very likely due to the much lower price.

These days it seems there is yet another FBL unit introduced every two weeks or so.

Charles
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Old Nov 17, 2012, 02:00 PM
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Thanks for those tips martin_. Mine's version 3.0.1. I've already increased parameter G one step above default, but I haven't played with the pot yet.

Don't get me wrong, I'm very happy with my Microbeast -- it got me flying without any adjustments whatsoever. And for a newbie to fbl, the way it doesn't require any setting up on the trannie, apart from throttle and pitch curves, is ideal. At the moment it's a little "different" from my flybarred 500, but I'm getting used to it and gradually figuring out (with help from this forum) what changes the various settings will make.
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Old Nov 19, 2012, 07:56 AM
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I would agree and disagree with this post <G>. A well setup flybar can be made to feel pretty good, however, it's only in trim at one point in the flight,..i.e. one attitude, one motion, otherwise it's out of trim, plus it's not consistent,..i.e. you can need some strange elevator mixing while doing a roll, that can be different going forwards, backwards, and sideways,.. so there isn't any consistency there. There's also the varying control rates with rpm. The opposite can be said for a flybarless unit, when properly setup,..i.e. it's ALWAYS in trim. I strive for a good feel like I could get with a flybar, not to jerky off center, and a smooth stop when releasing an input,..plus the desired overal rotational rate on each axis. however, the FBL system is ALWAYS in trim, and never changes control rates, allowing really low rpm flying for really long flights, with no loss of 3D ability. If you are one of those that want to fly "smack style" and hear the innefficient blade farting all the time, just up the rpms and you can do that too. In aerobatic autorotations you don't have to slam the stick all over the place, you simply fly normally and it gives you the same flip and roll rates regardless of the headspeed.
I think of a well setup flybarless system as flying just like the best flybar you ever flew but it's more stable, always in trim, and always consistent.

Quote:
Originally Posted by Gedexas View Post
Also, I'm not defending the $30 gyro, I know that when you get a flybarless heli, the last thing you want is for it to fly like a flybar does.
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Old Nov 19, 2012, 10:03 AM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
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That's what the cx3x1000 feels like. Like it's ready to drift in random directions as soon as you stop correcting it. Wind affects this particular FBL unit just like it did the flybar.

Let me clarify this a little.

Because the "hiller decay" is set in stone, the cx3x1000 is only capable of "rate mode" operation of the swashplate. If you ever flew your heli with rate mode tail gyro and then compared it to a heading hold tail gyro, you'd know exactly what I mean, except in this case it is not the tail, but the swashplate that behaves this way. This means that the cyclic feels like it is always out of trim, even when there is no wind.
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Old Nov 19, 2012, 10:46 AM
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What you're referring to as "hiller decay" (several FBL units call it that) is basically the integral gain in the PID loop. All of these use a PID loop algorythm on each axis. There are three tunable "gains" within this. The "P" or proportional gain is simply the amplitude of correction given when there is an error between sampled rate and the commanded rate. Gyros have always done this,.. and this is simply "rate mode", however, if they account for multiple samples before the present time, and adjust the amplitude of correction to maintain consistency, that is the Integral or "I" component. If you command 180 degrees per second for a pirouette and you're moving across the sky, a properly setup heli and "heading hold" unit will give you that rate since the continuous sampling, compared to the commanded rate are telling it to adjust the input to maintain consistency of piro . Then we get to the "D" or derivative gain. The unit knows the movement it's experiencing and it knows what you've commanded, and based on multiple samples, it knows when it will arrive at what you have commanded so increasing the derivative gain will basically tell it to arrive there quicker and stop firmer.

While this may not be the exact definition, it's pretty easy to remember that the three gains have these effects

P-amplitude of correction
I-consistency over time
D-stopping characteristics.

So, P is how hard it holds(too much can create wobbles), I is how consistent it behaves (too high and you can see a very slow oscillation, never gets fast, but also leads to porpoising in fast flight) and D is how hard it stops (Keep increasing till you get a bounce on stop then lower to just below that).
Everything else in the units is to tune pilot feel. The PID paramaters are how it actually does it's job, any and all other adjustments are the way you want it to feel in flight.
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Old Nov 19, 2012, 10:58 AM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
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Wrong answer.

PID loop has nothing to do with "heading hold". We can bet, I can send you the cx3x1000 and you will see for yourself.

The PID loop is responsible for the error between the commanded position and current position of the gyro. The problem begins when there is no error between the commanded and the current position, the hiller decay introduces an additional variable when it starts to account for the error between the gyro and the current position of the swash servos.

Basically, the gyro is "worried" that my swashplate is not level and "takes care" of the problem, even when it is perfectly fine for the swashplate to be off center, let's say, because the helicopter is tail heavy, or, let's say, when the wind is lifting one side of the rotor disk.
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