Item 0945
DESIGN: UniCopter ~ Power Train - Reduction - Primary - Engine @ 6º - All Gear
For use on Assemble
0925
Drawing:
Items that must be included, but Relocated or Modified:
The mechanical fuel pump is driven from the upper shaft. Can it be moved further aft, between the spiral bevel and the spur gear?
The Woodward governor is driven via the prop gear.
The following appear to be mounted below the gearcase;
The sensor for oil pressure.
The oil pump.
The sensor for oil temperature.
The oil filter.
Notes re Primary (Rotax) Gear Set:
The ratio is 2:43:1. These are Rotax standard gears.
It actually looks like the 2.43:1 is the option and the standard ratio is 2.27:1. This will have the advantage of allowing giving the secondary gears, centrifugal clutch and overrunning clutch higher safety factors.
The apparent distance between the centers of the two gears is 3.60". The ratio of the gears is 2.43:1 therefor the diameter of the large gear must be 5.1" and the small gear must be 2.1".
Notes re Mid (Spiral Bevel) Gear Set:
Arrow Gear Calculations;
for diametral Pitch of 6 and 24/24 teeth.Pinion has 4.1" outside diameter.
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Horsepower: |
85.4 |
hp |
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Pinion Speed: |
2058 |
rpm |
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Pinion Working Torque: |
2615.3 |
in-lb |
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Estimated Rated Pinion Torque: |
5230.6 |
in-lb |
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Catalog Rated Pinion Torque: |
2991 |
in-lb |
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Catalog Pinion Pitch Diameter: |
4 |
in |
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Pitch Line Velocity: |
2156.8 |
ft/min |
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Dynamic Factor: |
0.792 |
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Allowable Pinion Torque: |
2368.2 |
in-lb |
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Service Factor: |
0.9054 |
:1 (1) |
(1) The service factor is 0.90 for 24 teeth and a 1" face width. The service factor will be 0.59 for the same gear with 21 teeth and a face width of 13/16". In other words, 3 teeth and 3/16" in face width increase the service factor by 0.31. Therefor one more tooth (25 teeth) and an extra 1/16' in face width should result in a service factor of 1.0.
For 6 DP Final Gears:
6 DP is too light.For 1.06:1 ratio, the other sprocket should have 25 * 1.08 = 26.5 teeth; use 27 teeth.
Ie. 25 and 27 teeth for a ratio of 1.08, and a face width of 1.0625".
For 5.5 DP Final Gears:
This is the gearing that probable will be used. The mid gearing must have a ratio of 1.24:1 (31/25 teeth) to give 737 RRPM.
Direction of Thrust:
Looking from from to back, the driver is turning CCW, it has a Right Hand thread and the thrust is forward. The driven gear is on the port (right hand side), it has a left hand thread and the thrust is outward (away from the axis intersection point of the two gears).
Notes:
Ratio 2.45:1. 912 UL / A / F is 2.27:1 with option of 2.45:1
Use Rotax Housing as part of mold for new housing.
It might be beneficial to retain the Rotax Dog Hub, if possible, so as to remove any spikes from the governor. This might also reduce the demands on the couplings on the X-tube - X-shaft.
The Dog Hub will probably not work anyway since it must slide on the axially in the propeller shaft.Consider if torque spike absorber can be located within large primary (Rotax) gear. This will remove the spike from the governor, as well as the transmission to the rotors.
X-tube:
The X-shaft will probably be 1.3125" OD. The X-tube should clear the X-shaft by .25" minimum, therefor if the wall of the X-tube is .25" then its OD should be 2.3125". Make slightly larger at 60 mm.
Bearings:
This will eventually go on separate Group B page ???On Propeller Shaft at Aft Location:
This bearing is located in the engines housing and will not be touched. It appears to be a cylindrical roller bearing with a ID of 25 mm (0.98") an OD of 52 mm and a width of 15mm. This means that it is an NTN NU 205 with a dynamic basic load rating of 18,800 N or it is an NTN NU 205E with a dynamic basic load rating of 29,300 N.
For bearing calculation used; FORM: Rotor - Hub - Pitch Bearings ~ UniCopter
Do the calculations to see what the Rotax Reliability and Life is.
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Item Number: |
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Inside Diameter: |
25 mm |
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Bearing: [SKF number given] |
Nxx 205EC |
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Bearing: [NTN number given] |
NU 205E |
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Quantity and Type: |
1 - Cylindrical roller bearing |
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Basic Dynamic Load Rating: [C] |
29,300 N |
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Basic Static Load Rating: [Co] |
27,700 N |
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Radial Load Factor for the Bearing: [X] |
xx |
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Axial Load Factor for the Bearing: [Y] |
0 |
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Actual Radial Bearing Load: [Fr] |
xx N * |
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Actual Axial Radial Bearing Load: [Fa] |
0 N |
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Dynamic Equivalent Radial Load: [Prr] |
xx N ** |
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Basic Rating Life (in millions of revolutions): [L10] |
xx |
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Rotor Revolutions per Minute: [nn] |
2056 RPM |
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Basic Rating Life (in hours): [L10h] |
xx hrs |
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Reliability: [rr] |
?? % |
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Adjusted Rating Life (in hours): [Ln] |
xx hrs |
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Weight: |
0.026 lb. |
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On Propeller Shaft at Forward Location:
The bearing that is at this location in the standard Rotax gearbox is 6207 E TNH, 35 mm ID, 72 mm OD, 17 mm width deep groove ball bearing. This bearing has a a dynamic load rating of 25,700 N and a static load rating of 15,300 N (unless the 'E' or 'TNH' means more). The bearing is loaded by the propeller and the gear.
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FORM: Gear - Bevel
Using the gear Item 0953 (24 teeth, etc) the loads are; Radial = 582 lbs., Axial = 917 lbs. These values should be checked.FORM: Bearing Load Calculations for UniCopter
Using the gear Item 0953 (24 teeth, etc) the loads are; Radial = 229 lbs., Axial = 1026 lbs. These values should be checked.Also, the loading from the spur gear has not been included.
It looks that the following bearing should be at least Item 1015, when considering the Rotax's bearing above.
For bearing calculation used;
FORM: Rotor - Hub - Pitch Bearings ~ UniCopter|
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Item Number: |
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1015 |
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Inside Diameter: |
25 mm |
30 mm |
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Bearing: [SKF number given] |
SKF 32005 X |
32006 X |
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Bearing: [NTN number given] |
ET-32005X |
ET-32006X |
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Quantity and Type: |
1 - Spherical roller thrust |
1 - Spherical roller thrust |
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Basic Dynamic Load Rating: [C] |
27,800 N |
37,500 N |
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Basic Static Load Rating: [Co] |
33,500 N |
46,000 N |
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Radial Load Factor for the Bearing: [X] |
1 |
1 |
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Axial Load Factor for the Bearing: [Y] |
0 |
0 |
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Actual Radial Bearing Load: [Fr] |
4,617 N * |
4,617 N * |
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Actual Axial Radial Bearing Load: [Fa] |
1,032 N * |
1,032 N * |
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Dynamic Equivalent Radial Load: [Prr] |
4,617 N ** |
4,617 N ** |
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Basic Rating Life (in millions of revolutions): [L10] |
397 |
1077 |
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Rotor Revolutions per Minute: [nn] |
2056 RPM |
2056 RPM |
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Basic Rating Life (in hours): [L10h] |
3,219 hrs |
8,731 hrs |
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Reliability: [rr] |
97 % |
97 % |
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Adjusted Rating Life (in hours): [Ln] |
1,417 hrs |
3,842 hrs |
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Weight: |
0.251 lb. |
0.366 lb. |
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* [Fa] must be less than 0.43 * [Fr]. This is OK.
** See SKF page 646.
On X-tube - Port Side:
Basically, use the values form the propeller shaft above.
For bearing calculation used; FORM: Rotor - Hub - Pitch Bearings ~ UniCopter
Some of the following values will be incorrect.
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Item Number: |
1016 |
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Inside Diameter: |
60 mm |
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Bearing: [SKF number given] |
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Bearing: [NTN number given] |
32912XU |
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Quantity and Type: |
1 - Spherical roller thrust |
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Basic Dynamic Load Rating: [C] |
46,000 N |
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Basic Static Load Rating: [Co] |
78,000 N |
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Radial Load Factor for the Bearing: [X] |
0.4 |
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Axial Load Factor for the Bearing: [Y] |
1 |
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Actual Radial Bearing Load: [Fr] |
1,032 N * |
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Actual Axial Radial Bearing Load: [Fa] |
4,617 N * |
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Dynamic Equivalent Radial Load: [Prr] |
5,030N ** |
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Basic Rating Life (in millions of revolutions): [L10] |
1600 |
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Rotor Revolutions per Minute: [nn] |
737 RPM |
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Basic Rating Life (in hours): [L10h] |
36,175 hrs |
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Reliability: [rr] |
97 % |
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Adjusted Rating Life (in hours): [Ln] |
15,917hrs |
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Weight: |
0.251 lb. |
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** See SKF page 646.
On X-tube - Starboard Side:
For bearing calculation used; FORM: Rotor - Hub - Pitch Bearings ~ UniCopter
Most of the following values will be incorrect.
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Item Number: |
0792 |
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Inside Diameter: |
60 mm |
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Bearing: [Fafner number given] |
2MM9312WI CR |
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Bearing: [NTN number given] |
xxx |
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Quantity and Type: |
1 - Ball bearing |
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Extended Dynamic Load Rating: [C] |
22.700 N |
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Basic Static Load Rating: [Co] |
20,250 N |
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Radial Load Factor for the Bearing: [X] |
xx |
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Axial Load Factor for the Bearing: [Y] |
xx |
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Actual Radial Bearing Load: [Fr] |
xxx N * |
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Actual Axial Radial Bearing Load: [Fa] |
0 N * |
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Dynamic Equivalent Radial Load: [Prr] |
xxx N |
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Basic Rating Life (in millions of revolutions): [L10] |
xx |
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Rotor Revolutions per Minute: [nn] |
737 RPM |
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Basic Rating Life (in hours): [L10h] |
xxx hrs |
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Reliability: [rr] |
97 % |
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Adjusted Rating Life (in hours): [Ln] |
xxx hrs |
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Weight: |
xx lb. |
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Oil Seals:
This will eventually go on separate Group B page ???XX
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Last Revised: January 24, 2002