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Helix Carbon Prop Balance?


enzo200500
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Just weighed each of the carbon blades from my motor.

Two identical digital scales used.

457g total. Hub weight 281g Tip 176g

461g total. Hub weight 283g Tip 177g

465g total. Hub weight 291 Tip 174g

Now, are the differences enough to be concerned about?

Yes, its raining outside and I'm bored!!

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Is that tip to tip or o/all weight of each blade?

Difference between lightest and heaviest o/all is about 8g if I'm not mistaken?

Mmm, whats left?

How about Ti bolts on the hub to allow faster accelleration of the prop? Lower rotating mass?

Anodising, a cornucopia of colours available!

I know, ebay...................

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Will they send a courier out for the blades or do I post..... :wink:

Seriously though Si, I only checked the blades as when the motor was briefly run without a prop, it was hardly shaking. With prop attached, it was dramatically worse on the vibration front.

Really shaking on the mounting rubbers!

Could it be that the prop rotation was not absorbing the pulses from the engine, thus forcing the engine to rock on the power strokes?

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I bet propless it was shaking more than you could see:

[youtubevideo]

[/youtubevideo]

(This probably had a prop, who knows)

It's pretty common to hear belt squeak when a motor is cold and it's four or eight cycling like at the end of that video.

When my mini2/3blade is warm, it idles without squeak and *seems* amazingly smooth.

The prop acts as a mass damper to the engine pulses and acts backwards on four cycling, causing the belt chirps on subsequent firing.

At higher rpms it damps them better, and even more so when every cycle fires.

With no prop, there is nothing to react against (torquewise) other then the low mass of the engine and eyeballs aren't that fast.

With mass to counter the pulses, it gets uglier on idle:

[youtubevideo]http://www.youtube.com/watch?v=Vw8z9msIHEE[/youtubevideo]

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