Any ideas what caused the tail to go haywire?

[H-1Airframer]

This newly stretched plastic fantastic flew perfectly in the first flight. I'm not sure what happened to the tail on this flight. I did a hard pirouette both directions, then the tail started acting crazy. I had to auto it in. Luckily I saved it. Coulda sucked really badly, considering it was the second flight on a rebuild and stretch. Let me know what you guys think.

YouTube

YouTube

[PTcaflyer]

...Kv motor and gearing? Switch to idle up? What tail servo?
PT

[dunkonu23]

Listen to the noise the helicopter makes when you go to idle2. The pinion to front main gear mesh is incorrect. This causes vibrations that cause the tail to act exactly as you are experiencing. Additionally, as PT asked, please post your gearing and motor type and kv rating. You are running CF blades with the stock head assembly at what appears to be well over 2000 rpm that is not recommended at all.

Scott

[H-1Airframer]

Hyperion 3026-1000kv motor and 15-50-20-61 gearing. I haven't tach'ed the headspeed, but it should be right around 2000 according to the calculator. I'll hit it with a tach tomorrow.
So, you're sayin my gear mesh is too loose up front too, or too tight?

Edit: I checked the gear mesh, and it seems good to me. I use the paper trick and typically have no issues. I could be wrong. I've only been at this hobby for about 8 months. Help me out fellas.

[Seebodener]

according to the calculator you are right, but my ear and my feelings tell me that can´be right ... much higher headspeed
and -as Scott- mentioned there could be a problem with the front main gear, maybe the pinion came loose and is slipping under load ----> no pressure for the tail to hold.

Did you file a flat spot to the shaft to tighten the pinion on ?

[dunkonu23]

Gear mesh should be set for a tiny, and I mean tiny, bit of backlash at the closest point of the front main gear. With your gearing and motor, you're right, you're right around 2000 rpm but it sounded much higher. Are you sure you're using a 50 tooth front main? Reason I'm asking that is this: I've had super messed up pinion/front mesh and never got that noise at anything below 2350 rpm. If it's not the gear mesh, I'll be super surprised. When this happens again, you should try to go to idle 1 and see if the tail holds properly, again.

Another thing to try if you're not comfortable with the gear mesh solution is to check your belt tightness. It should be snug and give about 3-5 mm with light pressure.

Scott

[PTcaflyer]

Might check intermediate gear grub screws and OWB if they have been run for some time...sure sounds like overspeed ...550 sounds much slower...at least mine does in IU
PT

[H-1Airframer]

I'm positive I'm running a 50t front gear. I took off the 42 I had on previously. The OWB is brand new. The original failed on flight. I'll check the pinion (i did file flats) and other grub screws and report back. Oh, yeah, I'll tach it, too.

[H-1Airframer]

Just checked the grub screws on everything. They all looked good and secure. Does Antony think it coul be a faulty ESC, not giving consistent power to the motor? I'm running my backup esc, an Exceed Proton 60a. My Scorpion crapped out on me.

[dunkonu23]

Could also be a bearing not seated vibrating, but honestly, try it at idle 1 and see if you have the problem. I'm pretty darn sure it's headspeed related vibration causing this. Could even be a tweaked tail. In my case, it was the gear mesh, there's video out there that shows the problem with the noise, as well. I mean, out of nowhere, the tail would randomly kick 90 degrees. I had couple of ESC's in mine with no change, as well.

Scott

[H-1Airframer]

I know my tail is good. It's a brand new X5 tail pitch slider and hub and grip assembly. The tail output shaft isn't bent either from what I can tell. I'll double check the shaft though. I kicked the idle 2 TC down a couple of points to lower the HS a bit, and I also checked the frame screws, especially at the bearing supports. I noticed a little gear noise at the Aft main drive gear and put some synthetic grease on it. Now it's smooth as butter. I'll give it another test flight when I get some time.

[dunkonu23]

Check the boom supports. Make sure the plastic mount ends haven't come loose. I use JB Weld on mine. Once you do that, they're not going anywhere, ever.

Here's a link to the video I mentioned with extreme gear mesh noise. It's exactly what you have only I'm running much higher headspeed in this video.

YouTube

YouTube

This was solved by using proper gear mesh. While it didn't happen in this short video, the vibration did cause random tail kicks.

Scott

[H-1Airframer]

I'm using Outrage 550 boom supports, and they're solid as a rock. My gear mesh was a little loose, but I dialed that in a little better. I just haven't had a chance to test her again. Tomorrow, hopefully.

I really appreciate everyone's help with this, by the way.

[Mikej]

The headspeed sounds very high - are you sure that it is a 3026 1000 and not a 3026 1210 ? My other guess would be a static hit - have you lubed the belt ? What tail servo ?

It's a nice lookign heli ...

[H-1Airframer]

No. Haven't lubed the belt. What do I use? The tail servo is a Hyperion DS-20X GCD.

[PTcaflyer]

...Mike may have hit on something...Static!
Get some Silicone spray and use a Q-tip to apply to your belt...couple of applications at least...could only help!
I was wondering about the true motor Kv...do you have access to two different Tach's?
Get a comparitive reading...
PT

[H-1Airframer]

I'm positive on the KV of the motor, unless it is mislabeled on the case. I have some silicone spray in the trunk of my car, I think. I'll give it a shot.
Are you talking about the dry silicone spray?

[Mikej]

Originally Posted by H-1Airframer

I'm positive on the KV of the motor, unless it is mislabeled on the case. I have some silicone spray in the trunk of my car, I think. I'll give it a shot.
Are you talking about the dry silicone spray?

I'm in the UK so brand names won't help, but I use automotive stuff that is intended for lubing rubber door seals etc..

I had tail kicks in the early days of my 550s (never as big as yours) and a regular lubing of the belt has sorted them out. The Hyperion is a very good servo so unless there is something wrong with it you should be fine.

[H-1Airframer]

Yeah. That's what I figured. The spray I have is not the dry kind (for use on automotive window weatherstripping) so I'll pick up up a can at lunch.

[Mikej]

Yours may well be fine - I'veheard of people using shock oil from rc cars and even silicon oil intended for food production. Mine certainly goes on wet and then dries