Item 0735
DESIGN: SynchroLite ~
Rotor - Disk - Coning Angle (β0)
Outside Helicopters
|
Precone (βp) |
Ultrasport |
Indian |
Bell 206 |
Rotorway |
Robinson R-22 |
Mini 500 (Talon) |
|
Angle (deg.) |
3 |
3 |
2.5 |
2.5 |
* 2.56 (1) 2.17 (2) |
2 |
* Theoretical Only -
(1) Calculated using center of blade masses at 42" from root, teetering undersling 1-7/8" and all three centers inline.
(2) Calculated using GW [1370 lb] and centripetal force; [550 RRPM, 50 lb. blades, 42" to ctr. of mass.]. Crude calculation with no consideration for the actual weight at each element.
Note that blade mass includes grip and feathering bearing assembly, not just blade.
SynchroLite (2-blades)
Coning Angle, Mass and Moment:
This is from 1 disk and 1/2 the gross load (i.e. hover), from Access blade element calculations.
It is based on a tip weight of 0.75 pounds and using option 2.
|
Blade Element |
Weight [lb] |
Mass [slug] |
Moment [slug-ft^2] |
Cone [radian] |
Cone [degree] |
|||||||||
|
0 |
0 |
0 |
0 |
0 |
|
|||||||||
|
1 |
4.124 |
0.128 |
0.024 |
-.0007 |
|
|||||||||
|
2 |
0.374 |
0.012 |
0.020 |
.0004 |
|
|||||||||
|
3 |
0.374 |
0.012 |
0.055 |
.0043 |
|
|||||||||
|
4 |
0.374 |
0.012 |
0.107 |
.0106 |
|
|||||||||
|
5 |
0.374 |
0.012 |
0.177 |
.0195 |
|
|||||||||
|
6 |
0.499 |
0.016 |
0.353 |
.0310 |
|
|||||||||
|
7 |
0.499 |
0.016 |
0.492 |
.0453 |
|
|||||||||
|
8 |
0.499 |
0.016 |
0.656 |
.0622 |
|
|||||||||
|
9 |
0.499 |
0.016 |
0.842 |
.0818 |
|
|||||||||
|
10 |
1.299 |
0.040 |
3.033 |
.0723 |
|
|||||||||
|
Total |
8.915 * |
0.280 * |
5.759 |
.3267 |
|
|||||||||
|
Average |
0.891 |
|
|
.0327 |
1.8706 |
|||||||||
* Note: The weight and mass is calculated at the center of each element except for element 10 where it is calculated at the blade tip because the tip weight comprises most of the weight.
Acceleration due to gravity = 32.17405.
Mass = Weight [in pounds] / Acceleration due to gravity
Moment of Inertia = Mass * Radius^2
|
|
Tip Weights |
Lock Number |
Coning Angle |
||
|
|
0.00 pounds |
9.3792 |
2.7168 degrees |
||
|
|
0.75 pounds |
6.5274 |
1.8662 degrees |
||
|
|
1.00 pounds |
5.9253 |
1.6911 degrees |
||
"Tip weights don't affect undersling except for their contribution to total weight. With tip weights, the coning angle is shallower but blade CG is proportionately farther out." ~ Chuck Beaty
SynchroLite (3-blades CVJ)
Copied from;
DESIGN: SynchroLite ~ Rotor - Hub (CVJ) - Blade Generated Forces - PreliminaryRadius to the GG of the blade.
From above, the radius to the CG of the blade is 0.453R. Therefor r = (D / 2) * 0.53 = (16.0 / 2) * 0.45 = 3.6 ftAverage coning angle
= β0 = tan-1 (L / (b * CF)) = tan-1 (275 / (3 * 3,371)) = 1.56 degrees
FORM: Rotor - Disk - Coning Angle
Could be added here later for reference.
For initial rough calculations of the above see;
DESIGN: SynchroLite ~ Rotor ~ Initial
Back to top | SynchroLite Home Page | UniCopter Home Page | Dragonfly Home Page
Last Revised: October 20, 2004
