snjbird
Veteran
Location: Kissimmee, Florida- USA
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| Calculations
Trex 450 flybar paddles FRONTAL SA (CF) (50mm * 4.3) = 215mm^2
7.8g
Trex 600 flybar paddles FRONTAL SA (CF) (80mm * 7.5) = 600mm^2
12g
Drag coefficient is 0.05 (standard heli "wing" [blade] coefficient)
Fd = (p(u^2)Cd * A)/2
Fd is the force of drag, which is by definition the force component in the direction of the flow velocity
p is the mass density of the fluid
u is the velocity of the object relative to the fluid
A is the reference area, in our case this is the frontal Surface
Cd is the drag coefficient
p = 1.2kg/m^3 (air at 20C) = 1.2g/mm (thank God for the metric system)
u = 2200rpm and flybar paddle length from shaft is 170mm = Pi(170*2) * 2200 = 39145mm/sec (or 39.146m/sec or 87.56mph)
A = 215 for the 450 and 600 for the 600
Cd = .05
Fd(450) = (1.2(87.56^2).05 * 215)/2 = 49450g/mm
Fd(600) = (1.2(87.56^2).05 * 600)/2 = 138001g/mm
BUT
The 600 paddles are 1.54 times heavier so with inertial dampening of the drag effect you get an effectual resistance of 89611g/mm
Ok, so first, please check my calculations and logic. If you have any questions, please ask.
Conclusion: Through this data we see that the flybar paddles will require the motors total work load to be increased by a factor similar to that of the initial 450 flybar paddle. For the stability, its worth it for me.
Yes, my initial estimate to the size increase was wrong, and some of my units might be wrong here, but since they are all relative to one another, the comparison between the paddles is correct by my logic. Hope to hear from you guys soon.
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