Item 0889
DESIGN:
UniCopter ~ Power Train - Reduction - Primary - 3V BeltNote: "... selection of the number of belts may be made on the basis of approximately 1.75 times the rated belt capacity for light duty (helicopter) operations."
[Source ~ MDD p.79] I think, without having checked the below, that the following calculations can be revised as per this note.
3VX Gripnotch w/ 4 Grooves by Morse
(All calculations are approximately & are to be redone when details are tightened up)
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Input |
Rotax 912 S at 75%) |
Hirth F-33 85hp |
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Max. HP |
86 / 2 = 43 |
73 / 2 = 36.5 |
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Max. RPM |
5000 |
4750 |
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Max. belt speed |
5000 * pi * 5.5 = 7200 fpm |
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Design selection using 3VX Gripnotch belt Drive (Calculations from Morse catalog. p. G5) |
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1/ |
3VX |
3VX |
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2/ Service factor |
1.1 |
1.1 |
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Design HP |
43 * 1.1 = 47.3 |
36 * 1.1 = 40.15 |
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3/ d = |
5.5" diameter |
4.37" diameter |
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D = |
9.0" diameter |
8.0" diameter |
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9.0 / 5.5 = 1.63 |
8.0 / 4.37 = 1.83 |
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4/ |
5000 rpm |
4750 rpm |
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5/ |
4 * 15 = 60.0 hp. Require 47.3 hp. This is OK. |
4 * 11.61 = 46.4 hp. Require 36.5 hp. This is OK. |
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6/ |
47 / 15 = 3.13 sheaves |
40.15 / 11.61 = 3.46 sheaves |
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7/ |
C = Center to Center = 14" This can/will be changed. |
C = Center to Center = 14" This can/will be changed. |
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L = 2C + 1.57 * (D + d) + ((D – d)sq / 4C) |
L = 2C + 1.57 * (D + d) + ((D – d)sq / 4C) |
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= 28 + 1.57 * (14.5) + ((3.5)sq / 56) |
= 28 + 1.57 * (12.4) + ((3.6)sq / 56) |
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= 28 + 22.7 + (12.25 / 56) |
= 28 + 19.5 + (13 /56) |
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= 50.7 + .22 |
= 47.5 + .22 |
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= 51" |
= 48" |
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Make belt 51" inches. Optibelt 3VX ? |
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See p. 15 & 21 |
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8/ A/ |
15 hp + .62 hp = 15.62 hp |
11.61 |
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B/ |
15.62 hp * .96 = 15 hp. |
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C/ Loss in Arc of Contact |
= (D - d) * 57 / C |
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= 14.25 |
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Correction Factor |
= .96 |
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15 * .96 = 14.4 hp. |
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14.4 hp * 4 grooves = 57.6 hp. S.F. of 1.22. OK |
10 approx. * 4 grooves = 40 Hp. S.F. of 1.0 OK |
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Last Revised: June 15, 2003