Item 1899

DESIGN: Electrotor-SloMo - Rotorhead - Hub - A - Bearing Selection - Rotor

The following does not yet take into account the large gyroscopic moments between the two rotors.

Overview:

________________________

It appears that the 4-point contact bearing will not handle the RPM

Use Type A bearing for sure.

This leaves the choices to the Angular Contact Bearings.

Kaydon Bearing Calculations - Rotor Bearing: ~

Kaydon Bearing Selection: Page 14 in Catalog 300

Angular Contact Bearings [ARO]:

 

 

Bearing Number:

KD050ARO (1)

KD055ARO (1)

 KD060ARO (1)

 

 

Part Number:

 

 

Item 1580

 

 

Metric/Imperial:

Imperial

Imperial

Imperial

 

 

Weight: (lbs)

0.98 lbs x 2 brgs

1.06 lbs x 2 brgs

1.15 lbs x 2 brgs

 

 

Bore: (D)

5.00"

5.5"

6.0"

 

 

OD:

6.00"

6.50"

7.0"

 

 

Width:

0.50"

0.5"

0.5"

 

 

Ball diameter:

xx"

1/4"

1/4"

 

 

Radial - Static:

xx lbs

4,740 lbs

5,103 lbs

 

 

Radial - Dynamic:

xxlbs

1,790 lbs

1,890 lbs

 

 

Thrust - Static:

xx lbs

13,680 lbs

14,820 lbs

 

 

Thrust - Dynamic:

4,870 lbs

5,160 lbs

5,440 lbs

 

 

Moment - Dynamic (1)

-- lbs-in (2) (3)

-- lbs-in (2) (3)

-- lbs-in (2) (3)

 

 

Bearing separator:

R

R

R

 

 

Number of balls:

44

48

52

 

 

Derating factor: (Fl) (5)

20%

20%

20%

 

 

Charted figures: (Cf) (6)

15

15

15

 

 

Limiting Speed: RPM (N = (Fl * Cf * 1000)/ D) (2) (3)

1,250

1,250

1,250

 

 

Required RPM:

750

750

750
    1. See 'Type A Angular Contact' below:
    2. These have more than half the dynamic thrust rating of the Gyrobee bearing, and this craft has 300/505 the GW plus 2 rotors, but it will have greater moments.
    3. See Type A Angular Contact below, which is based on Manual page 83-84-85
    4. See 'Limiting Speed' algorithm below.
    5. I am going with a moment of 5,400 lbs-in. See above 'Overview' for reasons.
    6. On page 65

____________________

Forget 4-point Contact Bearings; ~ due to the rpm.

4-point Contact Bearings [XPO]:

 

 

Bearing Number

KF050XPO (1)

KF055XPO (1)

 

 

Part Number:

1843?

 

 

 

Metric/Imperial:

Imperial

Imperial

 

 

Weight:

1.05kg, 2.3lbs

2.5 lbs

 

 

Bore: (D)

5.0"

5.5"

 

 

OD:

6.5"

7.0"

 

 

Width:

0.75"

0.75"

 

 

Ball diameter:

3.8"

3.8"

 

 

Radial - Static:

6,490 lbs

7,050 lbs

 

 

Radial - Dynamic:

3,100 lbs

3,280 lbs

 

 

Thrust - Static:

16,220 lbs

17,630 lbs

 

 

Thrust - Dynamic:

7,760 lbs

8,200 lbs

 

 

Moment - Static:

18,660 lbs-in

22,040 lbs-in

 

 

Moment - Dynamic

8,920 lbs-in

10,250 lbs-in

 

 

Limiting Speed: RPM (2)

-------

-------

 

 

Bearing separator:

P

P

 

 

Number of balls:

23

25

 

 

Derating factor: (Fl)

1.0 (3)

 

 

 

Charted figures: (Cf)

3

3

 

 

Limiting Speed: RPM (N = (Fl * Cf * 1000)/ D) (2) (3)

 

436

 

 

Required RPM:

750

750

____________________

These are all 'X' bearings and their limiting speed rating may be low for the SloMo rotors. However, on page Kaydon page 64 it says "If a shorter life is acceptable, higher speeds may be tolerated, ....".
    1. Bearing is not sealed
    2. Values apply on bearings loaded up to 20% of their dynamic capacity. The Type X will not do.
    3. Based on mean loading with no Limit Load Factor and no SF.
    4. See 'Limiting Speed' algorithm below.

Limiting Speed: Page 64 in Catalog 300

N = (Fl * Cf * 1000)/ D ~ Ref. Design rotor speed 750 RRPM

 

Bearing:

KD055ARO

 

KD055XPO

 

KG050XPO

 

 KD060ARO

 

Part Number:

x

 

 

 

Item 1843 ?

 

Item 1580

 

Series: See page 6.

D

 

D

 

G

 

D

 

Bore: (D)

5.5"

 

5.5"

 

5"

 

6

 

Slimness Symbol: (SS)

I

 

1

 

I

 

I

 

Loading on Bearing: lbs-in

10,350

 

10,350

 

10,350

 

10,350

 

Dynamic Moment Rating:

8.920

 

5,110

 

15,250

 

5,440

 

Derating Factor: (FI)

.7

 

 0.1 ?

 

0.7

 

 .1 ??

 

Class and Lubrication:

1 & Grease

 

 1 & Grease

 

1 & Grease

 

1 & Grease

 

Charted Figure: (Cf)

15

 

 3

 

3

 

15

 

Limiting Speed: (N) RPM (1) (3)

 1364

 

 54

 

407

 

xx

 

Required Speed: RPM (2) (3)

750

 

 750

 

750

 

750

(1) N = (FI) (Cf) (1000) / D

(2) The RRPM of the rotors will be between 700 & 800, based on the diameter of the rotors etc..

(3) Type 'A' and 'C' bearings accept approximately 4 times the rpm speed as do the type 'X'. (ref: Fig. 47)

Capacity, Life and Load Analysis: Page 82 in Catalog 300

Life-Load-Speed Formulas: Page 82 in Catalog 300

The capacities are based on 1,000,000 revolutions, L10 fatigue life.

Lh = (16,667 / S) * (C / P)3

 

 

Bearing Number:

KD055XPO

KD055ARO

 KD055ARO

 

S

Speed in RPM

750

750

750

 

C

Kaydon dynamic load rating (1)

4,260 lbs. ? (1)

5,160 lbs. ? (1)

5,440 lbs. ? (1)

 

P

Applied load (2) (3)

4,906 lbs

7.179 lbs

7,221 lbs

 

Lh

L10 life in hours P is based on above formula.

14.5

8.25

9.5

 

Lh

L10 life in hours (2) P is based on Limit Load of 3 x Safety factor of 2 = 6; 150 x 6 = 900

2,356

4,188

4,188
    1. Radial or Thrust ???.
    2. This is based on the pilot continuously holding maximum cyclic force (150 lbs of pull).
    3. A combined loading (see page 83) for 'Type Four-Point Contact' is in the following section.

Type A Angular Contact: Page 83 in Catalog 300

 

Bearing Number:

KD055ARO

 KD060ARO

 

Radial Load per bearing: Fr (lbs)

150 x 36 * SF 1.5 = 8,100

150 x 36 * SF 1.5 = 8,100

 

Thrust Load: Ft (lbs)

(300 / 2) * SF 1.5 = 225

(300 / 2) * SF 1.5 = 225

 

Equivalent Radial Load: Pr = Fr + 0.9 Ft (lbs)

8,100 + 0.9 x 225 = 8,303

8,100 + 0.9 x 225 = 8,303

 

Input Variables:

 

 

 

PD

6"

6.5"

 

Center to center distance between bearings:W

0.5"

0.5"

 

Fr

8,100 lbs

8,100 lbs

 

Ft

225 lbs

225 lbs

 

Calculated:

 

 

 

PD' = PD + W / tanΘ =

6 + (0.5 / 0.577) = 6.866

6.5 + (0.5 / 0.577) = 7.366

 

X = PD' x sinΘ

6.866 x 0.5 = 3,433

7.366 x 0.5 = 3,683

 

Y = (PD' x sinΘ) / 2

(6.866 x 0.5) / 2 = 1,716

(7.366 x 0.5) / 2 = 1,841 

 

Z = PD' / 2

6,866 / 2 = 3,433

7,366 / 2 = 3,683

 

Moment M = +/- Fra +/- Ftb

8,100 +/- 225 =

8,100 +/- 225 =

 

Θ = 30Ί; sinΘ = 0.5

0.5

0.5

 

Sq-rt[Fra2 + Ftb2] =

8,103

8,150

 

Bearing Reaction = R1, R2, R3 & R4 =

 

 

 

Equivalent Radial Load = Pr = Rmax. x cosΘ =

8,103 x 0.886 =7.179 lbs *

8,150 x 0.886 =7.221 lbs *

* This is based on the pilot continuously holding maximum cyclic force (150 lbs of pull).

Type X Four-Point Contact: Page 85 in Catalog 300

Forget 4-point Contact Bearings; ~ due to the rpm.

Pr = (1.2M / PD Sin Θ) + 0.75Fr + 0.9Ft

 

 

Bearing Number

KD055XPO

KF055XPO

 

Fr

Radial load

50 lbs. (guess)

 

 

Ft

Thrust load: (3) From 1936

150 lb. * 3 * 2 =

 

 

M

Moment load: From 1936

10,350 lbs-ft

 

 

PD

Bearing pitch diameter in inches

6.0"

 

 

Θ

Bearing contact angle

30º for std. brg.

 

 

Pr

Equivalent radial load

4,906 lbs

 

 

Miscellaneous:

Type 'A' bearings appear to be best in a Back-to- back arrangement but need, or are better, with a spacer between them. (see; Fig. 30 and page 84).

With back-to-back bearings "The bearings are adjustable through the inner races by using shims under the inner race clamping ring." (see; Fig. 20).

Type 'A' bearings must be purchased as a matched set.

See note on page 57 re 'X' type re retainer an pocket opening down or extension on shaft or housing..

The KG050XPO, for which I have not yet done the calculations, may not be satisfactory in respect to RPM and in respect to capacity when looking at the Gyrobee's bearing above OTHER: Mechanics - Bearing ~ Gyrocopter.

If a pair of 12" square 'A' bearings are to be used then the billet should be moved up 1/4" and a 1/2" retainer used at the bottom.

Related Page:

DESIGN: Electrotor-Simplex ~ Gimbal - Bearing - Gimbal to Hub Selection

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Last Revised: December 29, 2010