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10-11-2005 02:39 PM  12 years agoPost 21
cyber-flyer

rrApprentice

Boston, MA

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I have replaced tail on my Eolo with the belt driven one last week.
On the first spool up the tail started to vibrate big time - about one inch amplitude on the vertical fin. The main head speed was set to around 2400 rpm. I slowed down the head to around 2300 rpm and saw no vibrations on the tail since then. I didn't investigate if vibrations whould reappear if I go back to faster head speeds. I think 3 mm tail axle is too thin to support Eolo tail at fast RPM and can easily enter resonance. This resonance onset depends on many parameters - balance of the blades, rigidity of the tail support, etc and therefore some people may see it happening while others not.
On the positive side - the belt driven tail turns out to be much smoother than the wire driven tail. I am using Eolo to carry small digital camera and with the new belt drive pictures are reasonably sharp at 1/100 exposure - about twice better compared to the wire driven tail.

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10-11-2005 05:37 PM  12 years agoPost 22
HugeOne

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Quebec, Canada

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Very interesting comments Cyber,

Since resonance is related to flexibility of the shaft a harder shaft will be a nice thing ( the harder the higher the frequency at which it will enter resonance, right?...) I'll ask my bro on how I can harden the stock shaft, I think it's not too complicated...

A HS steel shaft will surely do better...

Raptor e620 w/V-bar, Tango 45-06, Phoenix 85HV, TrueRC 12S1P 4000mAh

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10-12-2005 04:11 PM  12 years agoPost 23
Laurens

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Oegstgeest, NL

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Hugo, hardening is hard

First, you must know for sure that you have the right steel. I think there it has to be carbonsteel.

First heat it untill it has a nice orange glow. Then put in in water and stir after that.

Then sand it with some fine paper untill its grey again.

Now you have to yellow it. This is the hard part. Basically all you have to do is heat it untill it has a nice yellow color. If you heat it too long it'll turn blue. If it does turn blue you have to start over, but you you can only do that 3 times, after that the shaft will loose too much carbon.

Edge rotorblades, Scorpion systems

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10-12-2005 04:16 PM  12 years agoPost 24
cyber-flyer

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Boston, MA

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I agree, hardened shaft should do better. But I believe the stock one is already hardened. I'd look into replacing 3mm shaft with 4mm to run the extreme RPM. Of course all the bearings and hubs need to be changed to accept 4mm.
CF tail boom may also help - my guess it will be more rigid than the aluminum boom.

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10-12-2005 04:31 PM  12 years agoPost 25
HugeOne

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Quebec, Canada

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Thanks for the infos!

Boca have some nice 4x7x2.5mm bearing on sale now...

http://www.bocabearings.com/main1.a...2807&n=MF74-2GS

Now which heli use a 4mm shaft so we can steal it...

Wait, that mean finding a new pitch slider too... well it's complicated.

Raptor e620 w/V-bar, Tango 45-06, Phoenix 85HV, TrueRC 12S1P 4000mAh

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10-12-2005 04:54 PM  12 years agoPost 26
HugeOne

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Quebec, Canada

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Will this do?

http://www2.towerhobbies.com/cgi-bi...p?&I=LXSP44&P=7

Raptor e620 w/V-bar, Tango 45-06, Phoenix 85HV, TrueRC 12S1P 4000mAh

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10-12-2005 07:12 PM  12 years agoPost 27
demosa

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Tigard, Oregon, U.S.A.

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I don't think the stock tail shaft is hardened :
As part of my tail rotor balancing task, I hook up the tail rotor hub with blades on my home made "tail rotor spiner" (it's basically a dremel tool) and spin it up to 12,000rpm.
The first time I did this, I had not done static and dynamic balancing of
the tail rotor assembly first. As a result the CG of the assembly was off center and when I spinned it up the out of center situation was enough to make the tail rotor shaft look like a U. It pretty much ruined everything and the lesson for me was to first balance as good as I can then spin it up gradually (say a thousand rpm at a time).

If the shaft was hardened I think it would break instead of bent so much.

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10-12-2005 07:17 PM  12 years agoPost 28
demosa

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Tigard, Oregon, U.S.A.

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What about the tail pitch slider ?
I guess if you can find a heli that uses a 4mm tail rotor shaft then you'll also have a pitch slider that rides on that shaft.
But it may be tricky to attach the little Eolo links to that pitch slider.

How about using not only the shaft and the pitch slider but also the
grips and tail rotor hub from a bigger heli ?

On second thought I'm not sure what problem that would solve
at least in my case ... My Twist37/3s2p/15t Eolo is ultra smooth ...

This would be useful only for very high main rotor RPM, right ?

Demos

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10-12-2005 09:28 PM  12 years agoPost 29
cyber-flyer

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Boston, MA

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Eco (by Ikarus) has an optional HS tail shaft which is 3mm in diameter. I am not sure how much harder it is than Eolo's stock part. My guess is that 3mm to 4mm change will improve rigidity much more than hardening of 3mm shaft. Titanium is more flexible than steel, it should be even worse.
If anyone desides to go this way I think the easiest is to find a model with 4mm tail and steal the hub and slider mechanics, replace bearings on Eolo tail to 4mm ID and drill out tail pinion to 4mm. Not that I want to do it - my Eolo is the smoothest machine I flown to date

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10-13-2005 01:23 AM  12 years agoPost 30
HugeOne

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Quebec, Canada

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I think the ikarus HS shaft is better... for 12$ it have to be!
They have a nice alumium pitch slider also...

A helicopter with a 4mm TR shaft... rare thing I guess. Logo use 5mm, eco use 3mm, swift use 5mm, what's left... corona, voyager?

Edit: Voyager use 3mm

Raptor e620 w/V-bar, Tango 45-06, Phoenix 85HV, TrueRC 12S1P 4000mAh

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10-14-2005 05:19 PM  12 years agoPost 31
HugeOne

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Quebec, Canada

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I asked my bro about hardened shafts, he said he can make one up to rockwell 58. Don't know how hard it is, but to him it is VERY hard but still a little flexible so it won't shatter when bent.

Raptor e620 w/V-bar, Tango 45-06, Phoenix 85HV, TrueRC 12S1P 4000mAh

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10-14-2005 11:23 PM  12 years agoPost 32
rotaryguy

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Florida

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I sold my LI but this may help...
The viper 70 tail shafts are basically identical to the LI's, down to the notches in the shaft but are VERY soft. They do however offer a hardened version.

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