FBL Gyro Tail Creeping

[Spencer]

I recently had the maiden hover of my Trex 800E which has a AR7200BX and fount the the tail creeped counter clockwise and no amount of trim I put into the controller seemed to help.

is it possible that I do not have this heli in "heading hold"? I am thinking of redoing my initial set up sequence

 

[Tony]

Whatever you do, you MUST take all of that trim out of your Tx before you fly that helicopter. Never put trim of any kind on a flybarless controller.

HH will creep slightly and slowly, this is normal. It is searching for a specific "heading" and will keep adding pitch to the tail blades either until it reaches that heading or it runs out of pitch. To stop this right before you take off, have a setting on a switch with Rate mode and flip that switch into Rate and then back into HH mode and it will recenter your tail blades.

But definitely take all of that trim back out of that Tx.

 

[Smoggie]

As Tony said, remove the trim. I always disable trims in my Tx to avoid inadvertently adding any trim because you should never use it with a FBL.

Your tail gain is maybe too low which would mean that the tail doesnt hold position very well. Increase tail gain until you just start to get tail oscillation (usually in fast forward flight) then back down a few points.

 

[Tony]

I guess we should ask the question of, was this on the ground or in the air? I read it as on the ground. But if in the air, then what steve posted above is the way to do it.

 

[Spencer]

Ok thanks. I will make sure I remove all trim before my next flight. I am new to FBL systems, the last 600 I had was with FB. To answer the last question was it was creeping in the air not on the ground. I am also finding the throttle pitch curve very touchy as well. Any suggestions there to calm it down until I get a little used to the unit? I find my 500 with an Ikon a little easier to hover at a stable altitude

 

[Tony]

Make sure you have good gain set on the Tx for the tail. As Steve stated, add gain until you start to get a tail shake then back it down a bit.

As for the pitch curve being touchy, one thing to try that I use is a flat throttle curve. For normal mode as long as you have a good ESC with slow spool up enabled is to set your throttle curve to 0 65 65 65 65. This will tone down that aggressive pitch. For your pitch curve, set normal to 46 48 50 75 100 and set your idle up curves to linear.

 

[Smoggie]

FWIW my personal recommendation is never to use a 'normal mode' throttle curve. I just make all my throttle curves flat line 'idle up' type curves and the ESC in governor mode. On something like the Trex 800 I'd probably start with the throttle curves for my three flight modes set to 70%, 77% and 85% (maiden done in the 70% mode). My pitch curves would be the same in all modes 0%-25%-50%-75%-100%. Pitch range +/-12%

It's a personal thing to some extent but I've seen too many people crash their helis due to using normal mode, for example forgetting and trying to fly inverted in normal..

 

[Tony]

Running all idle up curves is fine for someone that has been in the hobby for a long time, but for a beginner I highly suggest they stick with a normal curve.

 

[Smoggie]

Fair enough Tony but personally I dont see the point of a normal mode curve on an electric heli, beginner or pro. Each to their own of course, it would be a boring world if we all had the same opinion!

 

[Tony]

The only reason I say for a beginner to stick with a normal curve is because the natural tendency is to drop the stick when they get into trouble. In IU, this would force the helicopter into the ground resulting in possibly more damage. In the normal mode I like to use for beginners, it only allows about 3º or so of negative pitch and it kills the motor at the same time.

For someone that has had time to train to always hit that throttle hold switch (which I HIGHLY suggest doing in a sim and doing it a lot) when they get in trouble, them absolutely go with a 3 mode IU and no normal. On my nitro, I have it set to 3 IU settings which are governed by the Ikon and I have obviously throttle hold as well as throttle cut to kill the engine.

 

[Smoggie]

Fair point Tony but the 'pulling back on the throttle stick' reaction is really only a problem for those who have previously flown planes or cars or FP helis. For a complete beginner to CP it isn't a natural reaction. In any case its something you absolutely have to get out of the habit of if you fly a CP heli. Regardless of flight mode pulling full back on the stick is going to cause a crash..

FWIW when I started on helis I'd been flying planes for 30 years or more so the throttle stick instinct was pretty well ingrained. What I found was that flying helis was 'different' enough that the throttle stick reaction didn't transfer over. From the start with helis I just looked at the left stick as collective, not throttle, so I used idle up curves. It worked for me.