1145

Item 1145

DESIGN: Dragonfly ~ Power Train - Bearing - Initial Gearbox - Selection
Note that the light gray values are temporary and NOT applicable to this helicopter

Add Safety factors etc. to load and or bearing selection.
Notes:

Use a Reliability of 98% and an Adjusted Rating Life of 2000 hours for initial gearbox bearings.

The Load Cancellations for these bearings came from: DESIGN: Dregonfly ~ Power Train - Bearing - Load Calculations

Am using FORM: PT - Bearing Calculations It looks like only the speed (rpm) needs to be entered in the top section.

Pinion Axle Bearings:

Nearest to Pinion:

Notes:

Consider tapered roller bearing , for weight reduction.

FORM: Rotor - Hub - Mast Bearings ~ UniCopter or

FORM: Rotor - Hub - Pitch Bearings ~ UniCopter

Item Number:	0525	xx	N
Bearing:	3MM207WI	xx	N
Basic Dynamic Load Rating: [C]	32500	xx	N
Basic Static Load Rating: [Co]	1630	xx	N
Radial Load Factor for the Bearing: [X]	1	1
Axial Load Factor for the Bearing: [Y]	1	1
Actual Radial Bearing Load: [Fr]	423	xx	N
Actual Axial Bearing Load: [Fa]	2727	xx	N
Equivalent Dynamic Bearing Load: [P]	3034	xx	N

Bearing Type:	Ball	xx

Basic Rating Life (in millions of revolutions): [L10]	2391	xx
Rotor Revolutions per Minute: [nn]	4500	2250	RRPM
Basic Rating Life (in hours): [L10h]	8855	xx	hours
Reliability: [rr]	99	99	%
Adjusted Rating Life: [Ln]	1860	xx	hours

Weight:	.7	xx	lb
1 Newton = 0.2248 Pound Force

Notes:

Furthest from Pinion:

	Item 0525	1 only	Fafnir 2MM207WI	98%	1718 hrs.
	Item xxxx	1 only	Fafnir 2MM305WI	99%	xx hrs.

Notes:

Consider a roller bearing, of the same physical size, as an alternate to the ball bearing if the shaft is to be subjected to a radial load from the attachment of a sheave.

Crown Gear Axle Bearings:

Nearest to Gear:
DK says that a 4-point bearing will be subject to galling.
FORM: Rotor - Hub - Mast Bearings ~ UniCopter

Location:		Inner Bearing:
Bearing:	Item 0869	SKF QJ 220 N2
Basic Dynamic Load Rating: [C]	76000	225,000	N
Basic Static Load Rating: [Co]	297000	240,000	N
Radial Load Factor for the Bearing: [X]	1	1
Axial Load Factor for the Bearing: [Y]	1	1
Actual Radial Bearing Load: [Fr]	9552	9552	N
Actual Axial Bearing Load: [Fa]	13206 *	13206	N
Equivalent Dynamic Bearing Load: [P]	22758	22758	N

Bearing Type:	Angular Contact Thrust Ball	4-point contact - ball

Basic Rating Life (in millions of revolutions): [L10]	37	966
Rotor Revolutions per Minute: [nn]	600	600	RRPM
Basic Rating Life (in hours): [L10h]	1035	26844	hours
Reliability: [rr]	97 *	99	%
Adjusted Rating Life: [Ln]	455	5637	hours

Bearing contact angle: [Theta]			deg.
Momentum Load: [M]			in-lb
Bearing Pitch Diameter: [PD]			in.
Equivalent Radial Load: [Pr]			lb
Weight:	8.69	8.91	lb
1 Newton = 0.2248 Pound Force

* xxx.

It may be better to use
FORM: PT - Bearing Calculations

	Item 1131	1 only	Fafnir 3MM9100WI	99%	1718 hrs.
	Item xxxx	1 only	Fafnir 2MM305WI	99%	xx hrs.

Notes:

Consider a single 4-point contact bearing for the mast, such as SKF - QJ 220 N2. It will be located between the rotor hub and the crown gear.

Furthest from Gear:

This may be the overrunning clutch complete with its own bearing.

	Item 0525	1 only	Fafnir 2MM207WI	98%	1718 hrs.
	Item xxxx	1 only	Fafnir 2MM305WI	99%	xx hrs.

Notes:

Back to top | Dragonfly Home Page

Last Revised: January 25, 2003