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Elec-Helicopters New or Limited Activity
Robbe › Vertical oscillation in tail
12-09-2004 03:00 PM  13 years agoPost 1
Heli431

rrNovice

Hertfordshire, UK

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I recently changed the tail gearbox on my Eolo to an aluminium one and added a nice CNC swashplate from heliup. Now I've noticed (although it may not actually be related) a small (<1cm or so) vertical "bobbing" in the tail when in the hover (i.e. tail boom seems to be vibrating up and down at a few cycles per second). Lateral stability is fine, holds just peachy with my CSM HH gyro (even when it detached itself from the adhesive mount - which was quite interesting in mid-flight!!!!).

Is this just a "normal" vibration or is something starting to go wrong?

Spirit Pro, F'glass main blades, Aveox Brushless, NiCD/NiMH batt packs

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12-09-2004 03:22 PM  13 years agoPost 2
darrens

rrKey Veteran

United Kingdom

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Sounds like something on the tail is out of balance. These are hard to find and could even be something as easy as the blade grips been over tight. Check blade grips, make sure the blades are balanced and check for gearbox play or out of true output shaft. Any form of oscilation is usually down to balance.
Also, the fin screws which hold the gearbox in the boom sometimes come loose and I have had this more often with the ali gearbox, worth a check.
happy hunting

He who dies with the most toys is the winner!

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12-09-2004 04:39 PM  13 years agoPost 3
cupra

rrApprentice

leicester uk

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i have the same prob same upgrades and it did it before i did the upgrades thats why i did them even put the new dive with the bearings in the boom the thing is it has done it since it was nearly new even have metal heads i also have a csm 420 gyro i have sab blades they have now told me to use thiner tape under the gyro all matal head and blade holders and boom has a twin brace on it on thing i noticed looking for the prod was the battery was vibrating but was not a total fix gain is set to 55% hh 70% normal it seems worse on hh

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12-09-2004 04:50 PM  13 years agoPost 4
psychopic

rrApprentice

Bournemouth - UK

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Are you guys sure it's not to do with your C O G or head speed. Turn the HS up a bit. I run 1820 on NICADS that may help. Also check that the COG isn't too far forward or back.

PP

Rappy 30v2, OS32, f3001 servos, S9243+GY401
Eolo Pro, C40 8L, Kontronik jazz,HS81's,GY401/s9254

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12-09-2004 04:57 PM  13 years agoPost 5
cupra

rrApprentice

leicester uk

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i admit the cog on mine is a bit far back but i run a lipo 5amp so its hard to get right have played with head speed up and down ? csm said try to put a piece of ply under gyro to change the frequency of the vibration but had already put a piece of carbon on top of the tray to stiffen it

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12-09-2004 05:59 PM  13 years agoPost 6
psychopic

rrApprentice

Bournemouth - UK

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I can't see how the gyro would have anything to don with vertical bobbing, horizontal maybe........

Rappy 30v2, OS32, f3001 servos, S9243+GY401
Eolo Pro, C40 8L, Kontronik jazz,HS81's,GY401/s9254

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12-09-2004 07:28 PM  13 years agoPost 7
cyber-flyer

rrApprentice

Boston, MA

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I had slow oscillations in roll axis. They would come and go. Eventually fixed it for good by putting metal main rotor head. It pisses me off that I have to buy expensive upgrades to make Eolo fly nice, but I do fly at main RPMs far exceeding 1800 rpm recommended by Robbe. And at 1800 rpm I didn't have any issues with vibrations.

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12-09-2004 10:41 PM  13 years agoPost 8
dnts

rrVeteran

Israel

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Heli431 - does this happen when it's windy? turn up your hover headspeed and they should go away. It's a known fenomena when the headspeed is too low and will happen also will all-metal heads etc.
Let us know,
Nir

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12-10-2004 09:08 AM  13 years agoPost 9
cupra

rrApprentice

leicester uk

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have got rid of my wag last night i put thin tape under it about half the thickness that comes with the csm mounted it side ways but i dont think that matters 60% gain if you want some tape posting let me know also had a csm pad under reciver have changed that as well just to see if that was moving the leads to the gyro well im happy with mine but i know how you feel i think some thing else to think about is i also fly were the wind can swirl i dont think this helped

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Robbe › Vertical oscillation in tail
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