Chineese weights, torque and vibs....

[mjdee14]

well, I had nothing to do today (wife still recuperating from back surgery) so i decide to take kahn's advice and see how much torque it takes to move the tail blades.....

I remove the head off the plastic frame Z20 ship and proceed to spin her up.....I have to say I WAS surprised at how much force it takes to move the blades from neutral...and the fact your servo is always fighting it to keep it somewhere out of neutral.....BUT I noticed that there were a lot of vibrations at the gyro, the horz fin was flapping like a gooney bird on steroids and casuing the tail servo to hunt...back & forth..... The other day while flying I kept trying to adjust the gain down as a the tail was moving back and forth but I didn't really see any vibs.....

So...I check the balance of the Gaui hub & blades...add a teeeeny bit of tape...no joy...still vibrating like heck.....I decide to tear apart the tail on the Z30 ship and try parts from that. First the Trexx 600 plastic hub and Gaui blades.....still vibrates.....I then try the gaui hub & blades on the Z30 cnc tail......and it vibtates also.....

The only way I get no vibs is with the hdx cnc tailbox and trex 600 hub assembley....smooooth as a kitten....no hunting.....

So I ordered a new tail box and trexhub for the Z20 ship.....

I also noticed it takes much less force to move the trex tail on spin up then it does the Gaui...maybe a better design and kind of has the proper weight distributed on the holders.

Well this took me about 2 1/2 hours......and cost $90...but what the hell...."I don't smoke"...

So now I get to wait for the postman like a dog in heat....:clappp

[Drew816]

So where do the Chinese come into your above equation; were they 'waiting' for your order, or should I say 'weighting?' :YeaBaby:

The HDX tail assembly with it's crank arm, a normal T-Rex 600 plastic rear fin holder thingie, what tail rotor shaft and what slider to you use on your Z30 and soon your Z20 bird?

I'm going to mimic this setup myself here in the near term so I'm just lining up the stuffs I'll need to order.

Happy Flying!

[kahn10]

could be bearings in your gaui tail case mike..... or those (receeding:nanabobo) hairline fractures that were mentioned a while back?..........oh yeah....and http://www.helifreak.com/showthread.php?t=82140&page=2 :happyd

[mjdee14]

could be bearings in your gaui tail case mike..... or those (receeding:nanabobo) hairline fractures that were mentioned a while back?..........oh yeah....and http://www.helifreak.com/showthread.php?t=82140&page=2 :happyd

Actually they are brand new bearings and a new tail case from the Z30 ship.....the Gaui hub and blade holders are the thrusted bearing holders......

there is just too much slop...and way too much vibration......was very surprised and how much it affected the gyro. Now with main blades off I might have been spinning up pretty fast but I still had the tail flutter with the mains on....

I should have played with the belt tension a little more...but this was all the excuse I needed to get another cnc tail case.

[Mikej]

Mike,

Can you confirm the exact set-up that gves you the best tail please - piece by piece if possible.

Thanks,
Mike.

[mjdee14]

I don't have the capability of copying on this browser...but I'm using the
Helidirect (sonix) cnc tailcase $26...the helidirect arm....helidirect slider....helidirect slider arms (bearings on both ends) and the Trex 600 stock thrusted hub/grips with stock Gaui tail blades.

One day i might spend the money on a good set of bearings from Boca... I think the stock bearings have a lot of slop i them....and the tail vibs show up in the form of resonance that gets to the gyro.

If you need...I can repost with links once I get to a better browser.

[Mikej]

If you need...I can repost with links once I get to a better browser.

If it's not too much trouble that would be very helpful.

Thanks,
Mike.

[kahn10]

had another big play with my tail grips last nite and got to agree with you on the bearings mike.there's maybe half a mm lateral freeplay at the end of the tail shaft and i know the bearings are tight in the tailcase.i'm going to try and find some quality replacements today i hate to think what that play translates to at speed :thinking

[mjdee14]

had another big play with my tail grips last nite and got to agree with you on the bearings mike.there's maybe half a mm lateral freeplay at the end of the tail shaft and i know the bearings are tight in the tailcase.i'm going to try and find some quality replacements today i hate to think what that play translates to at speed :thinking

Kahn.... I'm with you....I'm just surprised at the amount of play at the end of the tail shaft that can be felt by the looseness in the bearings.....I think Boca wants about 9 - 11$ each. I may just try some someday.....let me know if you find any good ones cheap.

You know it has to cause vibs with that bigg A$$ fan spinning on the end of it....

[kahn10]

can anyone remember offhand if the tail pulley has shoulders on it?the 4mm width is hardish to get my hands on but if i can skim a mm of each side of the pulley hirobo tail bearings slot straight in....and mike isn't it a surprise when you move the tail by hand!!!

[mjdee14]

can anyone remember offhand if the tail pulley has shoulders on it?the 4mm width is hardish to get my hands on but if i can skim a mm of each side of the pulley hirobo tail bearings slot straight in....and mike isn't it a surprise when you move the tail by hand!!!

The pulley has about a 3 1/2 mm shoulder on each side, however you will only be able to shave off very little on the side with the pin, unless you move the pin hole in closer to the pulley...

here is a picture.....

[mjdee14]

If it's not too much trouble that would be very helpful.

Thanks,
Mike.

http://www.helidirect.com/product_info.php?cPath=30_321_322&products_id=5889

http://www.helidirect.com/product_info.php?cPath=30_321_322&products_id=5890
the above two can be purchasd together from the first link and save dollar or two.

http://www.helidirect.com/product_info.php?cPath=30_321_322&products_id=5891

http://www.helidirect.com/product_info.php?cPath=30_321_322&products_id=5892

http://www.helidirect.com/product_info.php?cPath=38_233_242&products_id=2221

http://www.helidirect.com/product_info.php?cPath=38_233_242&products_id=1961

The above is everything I used to make my tail.....the fins keep the larger diameter out of the dirt...and I like the horizontal stab much better than the teeny weeny Gaui one. You have to file down the u clamp a little to get it tight on the boom.


**edit** you'll notice the EXTRA nuts on both sides of the blade holders....my attempt at the chineese weights.

[xomby]

Thanks mjdee!! That is VERY helpful!!!

[Mikej]

Thanks Mike.

[kahn10]

had a big play with bearings.surprisingly the gaui ones actually don't seem to bad.the biggest problem seems to be....wait for it.......ya ready......their goddamned tail shafts are slightly undersized.i've only checked two but they were both the same.the shafts rattle in the bearing.so....cheap ass(yeah you.and you.and y....shit all of us) bearing replacements.trex 450 main shaft bearings.you have to shave a mm off each side of the pulley.but slightly wider bearings are a good thing more support and they seat better in the tail housing.and next time you pull your tail apart get some bearing retainer gloop and basically glue the shaft to the bearings with it.don't panic thats what the gloops made for its easy to get apart again(no its not actually called gloop)

marco

oh yeah.and before you put it back together assemble the hub grips and blades.then take a shot glass empty it a few times then find a level surface put your tailshaft on the shot glass with the blades straight out and balance them.you may have to repeatedly empty the shot glass before achieving balance

[mjdee14]

After "4 shots" of Tequilia, I still can't balance my blades properly. they keep moving (along with the room) what am I doing wrong !! :dontknow:dontknow


All the cnc stuff arived and i put he new tail with trex plastic hub and trex fins. took itout and dialed in the tail...and it flew like a dream....steady as a rock.

No vibrations to the gyro, thus no unwanted servo movement.

This might be one of those places I just forgo the cnc part and stick with the trex hub. the holders are so beefey compared to the gaui, cnc would most likely be for looks only.

[kahn10]

keep going till ya eat the worm.....,just remember not to go and balance the neighbours kid who plays rap music to loud all night :)