19 tooth tail pulley

[kachur779]

Has anyone tried this new pulley yet? Just got one ,and it almost seems like you have to trim a little off the boom to make it fit

[Ah Clem]

I have had one installed for a while now. Also installed the aluminum tail case sides.

And yes, I did have to deepen the slots in the front of the tail boom and carve out a semi-circular area for the motor support bearing.

A friend of min installed a boom a few weeks ago, and did not have to modify it, so the newest booms may be a bit shorter.

[kachur779]

thanx Richard, i ended up taking heavy 1/8 off the boom and elongated the slots ,now i got it back together .The pulley is bigger and looks like it was made better than the original. Hopefully get in the air tmrw after work and see how it flys

[Ah Clem]

You are most welcome, sir!

Just as a side note, I had to adjust the settings on my FBL unit when I went to the larger tail pulley.

I have an AR7200BX on this machine, and I had to increase the setting on Pot 3 (Tail Stopping Behavior) quite a bit, due to the tail being less sensitive (I had Pot three turned quite a ways down with the stock pulley).

I could also run the tail gain quite a bit higher, resulting in overall better tail control.

[kachur779]

I did have some tail issues with full collective in fast hurricanes and funnels ,really hope this will fix those minor issues thanx again

[dannylightning]

i got one, i like it allot better. i did dremmel the boom a little where the boom was hitting the pulley assembly . and than made the slots a little longer.

so you do need to modify the boom unless you want a super tight belt. its very easy to do and well worth it IMO

[kachur779]

well took it for a test flight today only 1 cause it was dark after that flight ,i dont no if it was a combo of a new lipo and tail ,but i got a longer flight time.I like it the heli even has a different sound to it lol

[chrismechanic]

i would like a 19t tail pulley but no one stocks it in the uk yet
if i run my warp at 2900 rpm i get bad tail vibes, the tail push rod and the tail fin are vibrating.
i tried balancing, a new tail shaft and bearings, i dont think it is a bad part on the heli.
i think the tail is just too fast for high head speeds.
chris

[Bob O]

What about the bunch of us running above 3,000 RPM head speed on the 17T tail pulley with no issues? And the thrashing that Dave Ketelhut put on the Warp in a recent video? That was head speed higher than I've ever heard in any Warp video.

[chrismechanic]

i agree bob, i have seen the vids, i just dont seem to be able to resolve this issue, i cant get above 2900 with castle gov so maybe i need to switch off the gov and get the headspeed higher using the throttle curve.

there must be some truth in what i say, why make the 19t pulley if it not needed?

could be that im at a certain rpm where i am getting vibes, going higher might solve that, i have had this before on other helis.
chris

[Bob O]

Originally Posted by chrismechanic

i would like a 19t tail pulley but no one stocks it in the uk yet
if i run my warp at 2900 rpm i get bad tail vibes, the tail push rod and the tail fin are vibrating.
i tried balancing, a new tail shaft and bearings, i dont think it is a bad part on the heli.
i think the tail is just too fast for high head speeds.
chris

The 19T slow-down pulley has nothing to do with vibes. Regarding the tail being too fast for high head speeds, that is simply not true. I've run 3,200 RPM on the head with 60mm tail blades in fast backwards flight with no issues at all.

Originally Posted by chrismechanic

i agree bob, i have seen the vids, i just dont seem to be able to resolve this issue, i cant get above 2900 with castle gov so maybe i need to switch off the gov and get the headspeed higher using the throttle curve.

there must be some truth in what i say, why make the 19t pulley if it not needed?

could be that im at a certain rpm where i am getting vibes, going higher might solve that, i have had this before on other helis.
chris

If you can't get above 2,900 RPM, then you need to gear the heli up using a motor pinion with a higher tooth count. Regarding why the 19T tail pulley came out, it was to slow the tail down for those running higher head speeds.....I would say that equates to above 3,200 RPM.

The higher the head speed, the more authority the tail will have. Being that the stock tail already has gobs of authority, running high head speeds (ie: above 3,200) could cause tail issues. So for those running head speeds above 3,200 RPM, you might see better performance from the 19T slow-down pulley.

There are several things involved here that must all fall into place before just looking at head speed and tail pulley. For instance:

1. What size tail blades is a person running?
2. What type tail blades?
3. What position is the ball on the tail servo horn?
4. What is their tail gain?
5. What is their flying style?
6. Did they limit tail travel properly according to the manual?

In my case, I'm running Edge 60mm SE CF tail blades, the ball on my servo horn is at 7.5mm, my tail gain is 25, my flying style is 3D and fast backwards flight, and I limited my tail to the manual's specs for high head speed being that I'm governed at 3,100 RPM. I'm running the stock 17T tail pulley.

So if I wanted nothing other than to increase my tail gain, I would want the 19T tail pulley. If I wanted to run longer blades, I would want the 19T tail pulley. If I wanted to run a higher head speed, like 3,300 RPM, I would want the 19T tail pulley.

Deciding on which tail pulley is best for you is dependent upon several factors, vibes and motor gearing not being among them.

[Ah Clem]

Great information, Bob!

[Hawk404]

Originally Posted by Ah Clem

I have had one installed for a while now. Also installed the aluminum tail case sides.

And yes, I did have to deepen the slots in the front of the tail boom and carve out a semi-circular area for the motor support bearing.

A friend of min installed a boom a few weeks ago, and did not have to modify it, so the newest booms may be a bit shorter.

There's none better than ProStar hobby when it comes to fast and helpful communication so I took the liberty of asking about the boom.

The boom has NOT been shortened. Further, they report not knowing why I might want something like this as they are not aware of any issue with it being too long and have assembled several Warps without tail boom modification. I didn't ask if these specific models incorporated the 19t pulley.

It seems a proper belt tension should be achievable with the stock length boom presumably including the 19t pulley update. Any possibility these things (or maybe the tail belt itself) may be coming out of the factory with different lengths?

[Ah Clem]

"It seems a proper belt tension should be achievable with the stock length boom presumably including the 19t pulley update. Any possibility these things (or maybe the tail belt itself) may be coming out of the factory with different lengths?"

The only thing I can tell you is that I need to measure the booms to confirm.

I doubt there is a difference in belt length. My belt had quite a bit of time on it, prior to my changing to the 19 tooth pulley, so it is not a case of stretching things. The 19 tooth pulley is enough larger in diameter that the belt would have been too tight, had I not modified the boom.

It is possible there was a running change, but Compass and Prostar are in pretty close communication, so that would have been communicated.

Sorry I cannot answer your question properly and accurately.

[Hawk404]

Originally Posted by Ah Clem

The only thing I can tell you is that I need to measure the booms to confirm.

I doubt there is a difference in belt length. My belt had quite a bit of time on it, prior to my changing to the 19 tooth pulley, so it is not a case of stretching things. The 19 tooth pulley is enough larger in diameter that the belt would have been too tight, had I not modified the boom.

It is possible there was a running change, but Compass and Prostar are in pretty close communication, so that would have been communicated.

Sorry I cannot answer your question properly and accurately.

Thanks!

Actually I was speculating about something probably more far-fetched than belt stretch - I believe the belts come from here:
http://www.chinabeidi.com/en/en-index.php

With facilities in Zhejieng, Shanghai and Chengdu and exhibiting a great deal of flexibility in providing any size at all I'm wondering if there wasn't some movement in this area.

With apologies, this has mutated somewhat into an academic exercise: given two specific pulley diameters, a boom with some range of adjustment but of a fixed and repeatable length with a motor mount / tension pulley of limited movement there's insufficient tolerance stacking to provide observed results.

The stock tail assembly with fixed and repeatable dimensions and adjustment ranges should either work for everyone or no one. It's not that it shouldn't work for some but not others - it's actually mathematically impossible for it to behave that way.

Divorce it from a heli context and it's like reading that "2 + 2 = 4 usually but sometimes 2 + 2 = 3 or maybe 3.8 but it never equals 5". This probably wouldn't trouble me but my background was in mathematics so it kinda does.

So, as sheer speculation, I turn to the one part Compass can't possibly make in-house and minor variances in this part would explain observed results. This has a certain Occam's Razor sort of elegance but theories are never right because they're elegant.

This is from 1989 but it's interesting. Well, interesting to us nerd types. (Gate's tech bulletin on synchronous belts)

http://www.gates.com/facts/documents/Gf000289.pdf

[Bob O]

The possibility of having to do a 5-min mod to a tail boom shouldn't cause you that much aggravation.

[Hawk404]

Originally Posted by Bob O

The possibility of having to do a 5-min mod to a tail boom shouldn't cause you that much aggravation.

It doesn't bother me though with my luck and lack of experience I'd grind one that doesn't need grinding.

Don't we ever solve puzzles here just for the sake of solving them?

With all parts the same the thing simply can not be too long for some and not others. It's mathematically and logically impossible.

It's not that it has any major impact on the heli - it's merely mathematically and physically impossible that two identically dimensioned products could produce the anecdotes we're seeing.

You might be confusing aggravation with curiosity. Perhaps a heavy interest in RC Helis tracks down one's inner Sherlock Holmes, stomps it into a mudhole then walks it dry? Perhaps it'll happen to me eventually but I'm still at the point where, faced with mutually exclusive conditions, it's a mystery that might be solved.

You can't understand why I'd care - I can't understand why you don't - different strokes, different folks - all good.

[GravityJunkie]

Originally Posted by Bob O

The possibility of having to do a 5-min mod to a tail boom shouldn't cause you that much aggravation.

+1.

In my field of work, we call this 'analysis paralysis'.

Get your parts. Put it together. If it's tight, grind away what you need to make it fit correctly. The boom is an extremely simple part. It's not difficult to figure out. If you're stuck, look on the forum. I know I've see a pic of the boom that was modded.

[Hawk404]

Originally Posted by GravityJunkie

+1.

In my field of work, we call this 'analysis paralysis'.

Get your parts. Put it together. If it's tight, grind away what you need to make it fit correctly. The boom is an extremely simple part. It's not difficult to figure out. If you're stuck, look on the forum. I know I've see a pic of the boom that was modded.

I'm failing to make my point.

Forget the heli for the moment. Pretend for a moment that we're posting in a math / engineering forum.

It's a mathematical and logical puzzle - how can the exact same dimension parts produce differing overall dimensions when assembled by different people? Repeatedly but without discernible pattern?

The question is NOT whether it's a big deal. The question is HOW it happens.

The point has been made and accepted that I shouldn't care - let's move past that. Or not. But trust me, if I didn't read and grok it the first time I figured it out around the 5th time that I read it. Conceded. Nolo Contendre, Uncle!, I give.

But I still am interested in how it happens.

[Bob O]

Considering the forum, why should we "forget the heli"?

Maybe you can purchase a bunch of tail boom and tail belts, measure them all, and see if you can find some inconsistencies.