FBL Gyro If you have a Spirit gyro you must read this

[holtneil]

Hi guys this was found By smoggie you must read this
Something worth reading, having just read it i'm away to change my cyclic ring setting, now i know why the flips during rescue almost ripped the blades off!: Beware The Boomstrike!!! Set proper Cyclic Pitch. - HeliFreak

 

[Smoggie]

Good call posting it Neil. Although i never experienced blade strike the flip to the upright position when activating rescue from inverted was incredibly violent and cause the tail to blow out and the heli to end up pointing in unpredictable directions.
I just thought that 'that's the way the rescue worked' but apparently the cause is the misleading instructions that tell you to maximise the cyclic ring value to the largest number possible without mechanical binding. The Goblins have really good swash layout which means cyclic ring can be sky high before anything binds. This is good but if you follow the Spirit instructions you end up with the possibility of excessive cyclic pitch travel. It's not something you notice in normal flight but when you hit rescue and the heli flips upright it uses all the cyclic it has available and if there is too much travel bad things can happen, like the midair disintegration discussed in the thread.

The instructions have been updated now so hopefully it wont be an ongoing problem.

 

[murankar]

I never heard it called cyclic ring. I have heard it call collective ring, its a Futaba thing, well at one time it was anyways. What that does is insure you do not get binding of the swash when giving full collective while giving full cyclic, basically flying in the corners. It also allows the output to be a perfect circle thats in line worth your max throws. Any how with fbl controllers you don't need this feature. Now I dont own a Spirit so I cant say for sure how to turn it off, my guess would be to set the value to 0.

 

[holtneil]

Hi mate you just need to lower it so you dont get to much pitch in recovery mode the guy it happened to when he checked was getting 17.5 degs so it rips the heli apart as you hit the recovery mode
Hi Steve glad you found it I warned Rodney as he is getting the spirit for his heli , I hope Heliman450 reads it I may send him a message to be safe

 

[Smoggie]

Most FBL controllers have cyclic ring function . Mikado Vstabi software has it but i think it's only available for adjustment with the Pro upgrade, without Pro it might be stuck at default of 85? See attached screenshot of my Vstabi. I've had to reduce it in Vstabi before on my Trex 600 to avoid linkage binding in the corners.


Your description is correct but apparently in the Spirit (and possibly other FBL) is has the added function of setting an absolute travel limit for cyclic pitch, and that's what causes the problem if you have it too high.

 

[Smoggie]

So i've just checked my Spirit setup. Cyclic Ring was set to 230 which was the max available without binding, as per original instructions. When I checked aileron and elevator cyclic i was getting a whopping 15 degrees pitch (with collective at mid stick).

I reduced cyclic ring down to 175 which gives 10-11 degrees cyclic.... that will hopefully make rescue a little less violent and take out any chance of boom strike.

 

[holtneil]

Hi Steve checked mine on set up I did back it off so it is at 148 ,do you think this is to low ? I dont stick bang 3D so I would not know if this is right , I know your a busy man but as your my best mate do a video on how you check this I may under stand it more watching than reading NO Rush any time last week will do LOL

 

[Smoggie]

I'm no expert on it Neil, normally it's not something you need to worry about ...

So with that said, what I did was:

1. Connect up the heli to the Spirit software and open up the 'Limits' tab where the cyclic ring slider is.
2. Put the blades aligned along the heli nose to tail, put collective to mid stick (zero pitch) and put a pitch gauge on and zero it.
3. Apply full right cyclic and note the pitch angle reached, repeat for left cyclic.
4. Put the blades perpendicular and re-zero the gauge.
5. Apply full rear cyclic and note the pitch angle reached, repeat for forward cyclic (should be similar to #3).
6. Adjust cyclic ring up or down as required until blade angle is about 10 degrees or so.

If 10 degrees is optimum I'm not sure. lower won't do any harm but go too low and cyclic response will get a bit 'soft'. Too high and rescue gets too violent/dangerous.

 

[holtneil]

Ok Steve well that makes checking easy now you told this way I will do it tomorrow and set it to 10 degs

 

[Smoggie]

You probably have a bit less than 10 deg right now, and to be honest if you arent noticing any sluggishness on cyclic then that's perfectly ok.

 

[holtneil]

Hi Steve I like to have it right so I will re do it at the weekend and let you know what it had

 

[holtneil]

Hi guys well on checking I was getting a max reading of about 14 degs at the setting I first had I reduce to 148 just in case I wanted to fly before I checked the set up , now it's set up with the max of 10 degs with ring rate of 150

 

[Smoggie]

I had Goblin 630 out for a couple of flights today. The reduced cyclic ring works perfectly. Normal flight is unaffected but the flip to upright during rescue is now much less violent and no blowing out of the tail during the flip.

 

[holtneil]

Hi Steve that's really good news glad you found the write up so we knew about the problem

 

[Heliman450]

Hi all, I began my review of the information on this subject ready for when I connect up to the heli (one can't make the adjustments via the Jeti unless it's bound to the receiver). All I've got right now is my old memory and some screen shots I made during the process.........

In order to get the 6 degrees of cyclic geometry, I had to move out one step on the servo arms. I was then able to reduce the setting dramatically (down to 130 now). Currently, the actual degrees are unknown, so I need to check them to confirm that they're not excessive. However, as my current pilot skills don't reach to 3D or indeed, inverted anything apart from the approach into a crash I'm not too worried as I could do a maiden without the rescue feature set anyway.

With regard to the crash or explosion described earlier, I think that the danger of such an incident may be exacerbated when the blades aren't clamped in tightly enough to resist the force applied to them when the bailout is used. The blades won't normally move that much to hit the boom until they go out of chord alignment. During my time reading through Ray Hostetler's book, I picked up on this and since getting involved with a bigger heli I find it amazing the small adjustment necessary to achieve the correct alignment and the torque required to get the correct tightening to keep the blades in position.

Just a thought, any feedback appreciated.

 

[Smoggie]

The 6 degrees cyclic setting is not directly related to the problem. 6 degrees isn't the limit that cyclic will go to, it's just a calibration point so that the FBL knows where 6 degrees is.

The maximum cyclic travel range is limited by the cyclic ring setting and for safety you want to keep that around ten degrees (with collective at mid stick). The original instructions used to say to set cyclic ring to maximum mechanically possible but this could potentially give you something like 18 degrees of cyclic pitch which risks destruction of the heli regardless of how tight your blade grips are.
You don't see this during normal flying because the maximum roll and pitch rotation speed setting limits how much cyclic is applied, but during rescue the rotation speed limits are overridden and the FBL just applies everything it's got to flip/roll the heli upright.

The new (V2.0) software mentions the approx. 10 degrees limit on cyclic ring, so it's covered now.

 

[Heliman450]

Hi Steve, I realise what the 6 degrees are, but but I only had 4.7 degrees originally and needed to lengthen the throw just to get that.

I managed to do a quick check on the degrees and they were showing 12. Hopefully tomorrow, I'll run through the whole set-up again and double check everything whilst aiming for the reduced figure.

Thanks for getting back.

 

[Heliman450]

Hi all, so the latest software and firmware are downloaded, the whole set up process repeated (twice) and all's looking good. I'll give it the once over again in my workshop before giving it a maiden flight. Just need to prepare my videoing equipment ready for the event

Thanks for the heads-up, it came just at the right time.

 

[holtneil]

Your love it it's so locked in

 

[trainrider06]

The 6 degrees cyclic setting is not directly related to the problem. 6 degrees isn't the limit that cyclic will go to, it's just a calibration point so that the FBL knows where 6 degrees is.

The maximum cyclic travel range is limited by the cyclic ring setting and for safety you want to keep that around ten degrees (with collective at mid stick). The original instructions used to say to set cyclic ring to maximum mechanically possible but this could potentially give you something like 18 degrees of cyclic pitch which risks destruction of the heli regardless of how tight your blade grips are.
You don't see this during normal flying because the maximum roll and pitch rotation speed setting limits how much cyclic is applied, but during rescue the rotation speed limits are overridden and the FBL just applies everything it's got to flip/roll the heli upright.

The new (V2.0) software mentions the approx. 10 degrees limit on cyclic ring, so it's covered now.

On that 6 degrees how is that adjusted? By moving a stick on the radio or mechanically?? And what is adjusted if so???