Tail hold issue on 285 stretch. (Solved with 14 T pulley)

[soviet911]

Hey all.

I have been having an issue with my TE that I am not sure if it is due to tuning or the machine limit. On hard pitch pumps I get tail kick out of 30-60 degrees, I am running an ikon and MKS HV93i at 7.4 volts with 14 degrees of pitch.

I have tried increasing tail gain to 30, precomp to 50 and still I get a strong tail kick out (30-60 degrees), otherwise the heli fly's great. This happens regardless of head speed (2800,3200,3400) and I am running 50 mm tail blades? Anyone face this problem before? I am contemplating on getting the 14 tooth tail shaft to speed up the tail but want to see if I can try anything else before doing that (such as changing ikon settings).

My belt has only 1-2 mm of deflection max and I am pretty sure it is not skipping or at least it does not sound like it.

I did try using the outer tail ball hole on the servo but that had no impact as well, so I am pretty sure at this point I am maxing out the servo throw.

Any suggestions, if you have ikon settings that work well could you post them so I could compare.

Thanks

[jrman83]

Any play where the pitch lever and slider engage? Have you adjusted for max throw on the tail servo in the FBL?

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[scoio]

If changing iKon setting do nothing in terms of tail performance, I will definitely start to look into the mechanic of your tail. Start from the scratch and go through everything...bearings, linkages, screws....
I know is a standard question but... are you getting a buttered smooth tail?any frictions or binding?

I recently built the TE and tail is rock solid since the maiden flight.
If you are sure everything is ok and in order with the tail, start from the scratch to setup your tail with the iKon.
I usually follow these simple steps to get the tail rock solid (see post#9)
https://www.helifreak.com/showthread.php?t=664506

Hope it helps

[soviet911]

The mechanics are good and I have set the throws so the tail has full range of motion. Hence why I think its a gains issue, or tail ratio issue.

@scoio: Thanks I will try following that post and see if I can get it to hold well. I have tried playing with the gains but I never got the tail to come close to oscilation, so I will give that a go maybe my gain is just too low.

[Mikej]

You are the high-end for pitch and the low-end for HS - my guess is that the torque of the blades is over-powering the tail's ability to compensate. Try the speed-up gear for the tail or upping your HS a bit...

[jrman83]

Yeah, that HS with that much pitch, it would seem it would bog quite a bit. 3600-3900 is my range. Have tried bumping HS up some? I would also go to the 14t if you plan to stay that low.

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[soviet911]

Thanks jrman83 and MikeJ: I figured it must be the issue at this point. I will try tunning it and see if it works but otherwise I will grab a speed up pulley as I will stay at this low HS for a while.

[Wargamer]

I find 3200 to 3400 is very relaxed on the stretch, and the longer flight times are nice. With the 14t pulley and a KST215 I have no issues.

[soviet911]

Originally Posted by Wargamer

I find 3200 to 3400 is very relaxed on the stretch, and the longer flight times are nice. With the 14t pulley and a KST215 I have no issues.

Thanks. I will order the 14t pulley and see how it works.

[jrman83]

Does it happen at your highest HS?

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[soviet911]

I tried to tune it out but no luck, the tail kick out occurs at 3200,3500 RPM even with pitch precomp of 80... Ordering the 14 T pullet, should help resolve the problem.

[Jurbin]

I've also seen gov gain cause this type of issue. I would guess that the extra pitch at lower headspeed would make it more difficult to keep steady.


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[soviet911]

I am using ikon gov and have a 10t pinion on motor so I don't think it's a bog issue. I will report back once my 14t pulley arrives.

[soviet911]

Got the 14t pulley, the tail hold is now solid! Love that oxy provides all of these options to fit anyone needs.

[jrman83]

Glad to hear it

[NewToRC]

Mine is torn down waiting for a new one way hub but I installed the 14t pulley as well. I'm hoping it takes care of my problem too. Thanks for sharing.

[soviet911]

Originally Posted by NewToRC

Mine is torn down waiting for a new one way hub but I installed the 14t pulley as well. I'm hoping it takes care of my problem too. Thanks for sharing.

Make sure it is not binding up your bearings. I had to sand the side of the pulley a bit so it would not preload them.

[NewToRC]

Everything is smooth as glass and the 14t pulley is polished. Just waiting on parts to get rid of the main shaft vibe. I will let you know the outcome.

[jrman83]

Curious where you see the main shaft vibe? If it is during start up or shut down, this is usually having the mains too tight or not tight enough. Or, all 3 bolt attaching shaft to the hub are not tight.

[soviet911]

Originally Posted by NewToRC

Everything is smooth as glass and the 14t pulley is polished. Just waiting on parts to get rid of the main shaft vibe. I will let you know the outcome.

The tail will be smooth as glass even with pre-loaded bearings which can show up as wag or as overheating, you should have a little play (0.01 mm or so) between the pulley and the bearings to prevent the pre-load.

Not sure about the main shaft, I have a moderate vibe problem on spool up and spool down on my 470L but the oxy 3 is vibe free.