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HelicopterMain Discussion › OK, I'm confused now....! Blade balancing question for the engineers out there.....
11-26-2007 05:42 PM  9 years agoPost 101
AirWolfRC

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42½ N, 83½ W

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The see-saw method is a simple balancing of moments.
The moment is the weight times the distance to the weight.
So long as the moments are equal, you will have balance.

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11-26-2007 05:47 PM  9 years agoPost 102
Mark C

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Houston, TX - USA

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Follow up

I wanted to do a lot of testing before getting back to you about blade balancing. I work 8-5, it's dark when I get home so I can only fly at weekends, weather permitting, which is very rare at this time of year in Ireland.
Thanks for the follow up Hamo! The empirical data backs up the math. Great stuff.

I feel your pain on getting in flight time. Last weekend here in Texas is the first bad weather no fly weekend I can remember. Now that it gets dark here at 5:30 the only flying I'm getting in is before work and at lunch time.... and of course on weekends!

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11-26-2007 06:28 PM  9 years agoPost 103
chris24g

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Hayward, CA

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I guess if you really want to see an example of miss matched CGs, just think about the old NASA footage of astronauts in the centrifuge. Granted they weren't revolving 33.3 x/sec, but you get the idea.

That being said, using my Koll Rotor Pro just makes me feel so... helicopterish.

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11-26-2007 07:54 PM  9 years agoPost 104
AirWolfRC

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You want mis-matched CGs ?

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11-26-2007 08:01 PM  9 years agoPost 105
chris24g

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If you had shown that picture first, this thread would be only 1 page in length.

I want to try that at my local field.

My intuition tells me, however, that autos are out of the question...

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11-26-2007 08:04 PM  9 years agoPost 106
AirWolfRC

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I linked to this image in the 20th post in this thread.

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11-26-2007 08:12 PM  9 years agoPost 107
spork

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Mountain View, CA

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This rotor system will be dynamically balanced, but it has another significant source of vibrations.

Anyone?

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11-26-2007 08:16 PM  9 years agoPost 108
AirWolfRC

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The lift vector is displaced from the central vertical axis but the oscilation or vibration produced from this is undetermined.

You want to try it and let us know ?

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11-26-2007 08:20 PM  9 years agoPost 109
psych-lick

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Portland, OR

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How would test the tracking on that thing?

-Jeff T.

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11-26-2007 08:24 PM  9 years agoPost 110
spork

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Mountain View, CA

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The lift vector is displaced from the central vertical axis
Yup. So how could you fix that?
but the oscilation or vibration produced from this is undetermined.
I don't know what you mean

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11-26-2007 08:28 PM  9 years agoPost 111
AirWolfRC

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Yup. So how could you fix that?
You don't.
I don't know what you mean
The lift summ from the single blade is rotating around the main shaft causing a "wobble" in the airframe at whatever the head speed is. The amplitude of this "wobble" is what is undetermined.

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11-26-2007 08:37 PM  9 years agoPost 112
spork

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Mountain View, CA

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Q: Yup. So how could you fix that?
A: You don't.

You do if you're clever
The lift summ from the single blade is rotating around the main shaft causing a "wobble" in the airframe at whatever the head speed is. The amplitude of this "wobble" is what is undetermined.
I still don't know what you mean by "undetermined". Everything about the system, including the amplitude of the exciting force, can be known.

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11-26-2007 08:46 PM  9 years agoPost 113
AirWolfRC

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You do if you're clever
This I want to hear.
. . . . . can be known
It certainly can . . . . . but I have not measured it.

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11-26-2007 08:47 PM  9 years agoPost 114
Mark C

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Houston, TX - USA

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The lift vector is displaced from the central vertical axis but the oscilation or vibration produced from this is undetermined.
Yea but we know that the oscillation is going to be 90 degrees out of phase with the blade.

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11-26-2007 08:48 PM  9 years agoPost 115
AirWolfRC

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Correct . . . . .

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11-26-2007 08:49 PM  9 years agoPost 116
f penfold

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uk

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control line speed only use one sided props aswell its surposed to be more efficient

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11-26-2007 08:51 PM  9 years agoPost 117
bagobitz

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saddleworth,lancs,UK

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duh....you shape the weight like a flybar-paddle?...IE a squatty aerofoil section.

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11-26-2007 08:54 PM  9 years agoPost 118
spork

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Mountain View, CA

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This I want to hear.
You just need a teetering system so the blade can't transmit any moment to the mainshaft.

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11-26-2007 09:02 PM  9 years agoPost 119
AirWolfRC

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How do you propose to acomplish this ?

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11-26-2007 09:02 PM  9 years agoPost 120
Billebob

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Tim-buck-2

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It's nothing revolutionary, actually the idea is quite antiquated.

http://www.lidak.it/

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HelicopterMain Discussion › OK, I'm confused now....! Blade balancing question for the engineers out there.....
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