Item 1040
DESIGN: UniCopter ~
Rotor - Blade - General - Thickness
Average Drag Divergence Mach Nbr. at Zero Lift for Airfoils: [Source ~ RWP1 p.410]
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Thickness / Chord Ratio: (t/c) % |
Drag Divergence Mach Number: (MDD) |
Velocity: (ΩR + R) fps (1) |
Radius: (r/R) (2) |
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6 |
0.90 |
856 (0.79M) (3) |
1.0 |
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9 |
0.85 |
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.85/.9 = 0.944 |
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12 |
0.80 |
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.80/.9 = 0.889 |
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15 |
0.77 |
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.77/.9 = 0.856 |
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18 |
0.75 |
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.75/.9 = 0.833 |
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(1) At a forward speed of 160 kts (270 fps) and a blade tip speed of 586 fps
(2) The location where the drag divergence will take place for the given
t/c(3) The ABC design rotor speed = 650 ft/sec; in helicopter mode; 450 ft/sec. in compound mode. At 250 mph
ΩR + R is mach 0.75. The CalVert tip speed is 722 ft/sec in hover and 623 ft/sec in cruse. At 180 kts ΩR + R is mach 0.85Twist will cause the inner segments to probably have a lower drag divergence mach number than the values given above.
Notes:
Note
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Last Revised: February 19, 2002