Item 1139

DESIGN: Dragonfly ~ Power Train - Bearing - Final Gearbox - Load Calculations

Calculations of loads on mast bearing (s?) from rotor and drive train.

Moments & Forces ~ from Rotor and Final Crown Gear: Some of the upper portion of the drawing will be revised and simplified. On drawing change A0 to Beta0

 

 

Load from Rotor: Loading on bearing from the rotor. Values come from DESIGN: Dragonfly ~ Rotor - Hub - Load Distribution:

 

Symbol:

Value:

Description:

 

RRPM

650 RPM

Rotor speed, at 100%. ~ Ω = 68 radians per second

 

V

22º

Angle between masts.

 

D1

6.1" ~ Item 1156

Diameter of mast bearing, at center of rolling elements (D + d) / 2.

 

D2

7.4"

Vertical distance from rotor's virtual hinge to center of mast bearing. Temporary Source of value

 

D3

2.7"

Vertical distance from center of mast bearing to centerline of pinion. Temporary Source of value

Lift: (L) at hover = 275 lbf.

Thrust: (T) at hover = L / cos(V/2) = 275 lbf. / cos(12) = 281 lbf. [1,250 N]

Moment from 12º of Flap: xx

Centrifugal Force: (CF b)

sin(28.73) = 0.481

Moment = +622 lbf * 15.4" = +9,580 lb-in

Horizontal component of right blade = 3,213 lbf * 7.4" = 23,776 lbf-in

Horizontal component of left blade = -3,285 lbf * 7.4" = -24,309 lbf-in

Resultant = +23,776 - 24,309 = -533 lbf-in

Vertical component of right blade = 683 lbf * 13.5 = -9,220 lbf-in

Vertical component of left blade = 0

Resultant = -9,220 - 0 = -9,220 lbf-in.

Resultant = -9,220 -533 = -9,753 lbf-in. [-43,383 N] CCW

Combined Forces:

Force on right hand side of race = 208 + 1,853 = +2,061 lbf. [9,168 N]

Times 4 [LLF] and 1.5 [SF] = 12,366 lbf. [55,000 N]

Load from Final Gear Set: Will this be eventually calculated on a separate page and just the crown gear forces transferred over?

FORM: PT - Bevel Gear Forces:

Load:

Port Rotor

Starboard Rotor

Horsepower

25

25

Speed

2250

2250

Pitch Diameter

2.143

2.143

Tangent Load

1307 lbf

1307 lbf

Bevel Gear:

Gear - Pitch Diameter:

7.8571

7.8571

Face Width:

1.0

1.0

Tooth Pressure Angle

20º

20º

Helix Angle

35º

35º

Ratio

3.67:1

3.67:1

Pitch Cone Angle of driving member (pinion)

15.255º

15.255º

Rotation of driving member (pinion)

CW

CCW

Helix Spiral Direction of driving member (pinion)

Left-hand

Right-hand

Forces:

Radial Gear Load (separating force) - Driving Side. ~ Pinion 'G' (1)

182 lbf

182 lbf

Parallel Shaft Load (axial load) - Driving Side. ~ Pinion 'F'

591 lbf

591 lbf

Radial Gear Load (separating force) - Driven Side. ~ Crown 'E'

591 lbf

591 lbf

Parallel Shaft Load (axial load) - Driven Side. ~ Crown 'D' (1) (2)

183 lbf

183 lbf

Notes:
    1. Assumes that pinion is located below crown.
    2. This value is small therefore there is little reason for not putting pinion under the crown and it may be better if and when the rotor drives (from lead-lag).

Radial Gear Load (separating force) - Driving Side. ~ Crown 'E'

-417 lbf

-417 lbf

Parallel Shaft Load (axial load) - Driving Side. ~ Crown 'D'

457 lbf

457 lbf

Radial Gear Load (separating force) - Driven Side. ~ Pinion 'G'

457 lbf

457 lbf

Parallel Shaft Load (axial load) - Driven Side. ~ Pinion 'F'

-416 lbf

-416 lbf

Notes:

For bearing selection from the above Load Calculations see: DESIGN: Dragonfly ~ Power Train - Bearing - Final Box Selection

For reference see: DESIGN: UniCopter ~ Rotor - Hub - Bearing - Mast

Pinion Bearings:

Distance between gear and bearing is not relevant because gear is straddle mounted.

Distance between bearing and bearing is not relevant because gear is straddle mounted.

Nearest to Craft's Centerline:

Engine (pinion) Driven:

Radial load: 1/2 of 182 = 91 lb-force

Axial load: = 591 lb-force

Rotor (gear) Driven: (from lead-lag)

Radial load: 1/2 of 457 = 229 lb-force

Axial load: 0 lb-force

Furthest from Craft's Centerline:

Engine (pinion) Driven:

Radial load: 1/2 of 182 = 91 lb-force

Axial load: = 0 lb-force

Rotor (gear) Driven: (from lead-lag)

Radial load: 1/2 of 457 = 229 lb-force

Axial load: -416 lb-force

Crown Gear / Mast Bearing(s):

Single Bearing:

Values come from Load from Rotor: and Load from Rotor: above.:

~ Alternate (if 2 bearings used) ~

FORM: Bearing Load - Secondary Pinion (straddled gear)

Am not currently using above form at present since I am considering just one gear. Have just done measurements and calculations it roughly.

Distance between gear and bearing: 2"

Distance between bearing and bearing: ?" ~ There may not be a second bearing.

Nearest to Crown:

Radial load: 613 * 5/4 = 766 lb-force

Axial load: 63 lb-force

Furthest from Crown:

Radial load: 613 * 1/4 = 153 lb-force

Axial load: 0 lb-force ~ There may not be a second bearing.

Same Page ~ Different Craft: ~ Not quite, but probably in the future ~ UniCopter

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Last Revised: July 22, 2003