B209

DESIGN: SynchroLite ~ Control - Flight - Swashplate

Outside Helicopters

UltraSport:

The swashplate is not a Uniball. It is a gimbaled ring.

It weighs approx. 10 lb.

Looks like about 5-1/2" to 6" OD.

See Sun 'N Fun picture of hub.

Indian:

Uses MRC7015-3 bearing for swashplate or Fafnir equivalent.

Length of "arm" on swashplate, to hub: 2.7969"

Length of "arm"" on swashplate, from mixer box: 4.375"

Control bearings are 1/4 bore"

Hiller FH1100:

It has 2 angular contact radial ball bearings.

Bell 206:

I think the swashplate ring bearing in the 206 reads "KAYDON 11066 8B1". I have their Internet address bookmarked and there is a program re calculations and DXF that can be downloaded.

There was a slightly larger thin bearing at BCIT and printed on it was "Fafnir Y96PW1-2".

Upper and Lower bearing planes:

Robinson - look like they are not quite in the same plane.

Bell 47 - are in the same plane.

Bell 206 - not in the same plane.

Aerospatiale - not in the same plane.

From: Helicopter Flight Dynamics p.17:

Each individual blade has a pitch range of more than 30 degrees.

SynchroLite

Tilt:

The maximum amount of angular travel is -9º,+13º on the longitudinal cyclic. The inner ring, which is connected to the hub, must therefore have an angular travel of at least -13º to +13º, a total of 26 degrees.

The arm length ratio between the swashplates inner ring and the arm length of the pitch arm is 1:1 therefore design the swashplate for -14º to +14º of angular movement.
Uniball:

Uniball could be hydraformed if quantities are large, otherwise CNC machine.

For uniball look at Wemac swivel eyeball air vent at top of page 165 in Wicks Aircraft Supply.

Torrington has Spherical Radial Bearings with tilting angle of 14 & 14 = 28 degrees.

Teflon Coating

On Nov 6 98 I spoke to Ron Colson at Custom Plastics [67] in Vancouver. They can Teflon coat aluminum. Their coatings are normally .0001" to .0002" thick but they can go thicker. The name at Colson that was given me by Rick at Andrew & Associates was Lea Harris.

Bearing:

Axial Load:

Collective movement = Movement of stick * (3 / [collective stick length]) = 1" * (3 / 26") = 0.115"

There fore a pull of 100# on the collective stick will result in a force of 100 / 0.115 = 887# at the "mixer box".

This means a force of 887 / 2 masts = 444# axial thrust load on each swashplate bearing.

Radial Load:

The radial load should be negligible.

Moment Load:

Movement = Movement * (1.375 / CyclicStick) = 1" * (1.375 / 17.866") = 0.077" Rod movement.

Length of arm at swashplate is 3.5"

There fore a sideward push of 50 # on the cyclic will result in a force of 50 / 0.077 = 650# on the control rod. Half of this force will be pull on one rod and half will be push on the other.

This means a force of 650 / 2 masts = 325# * 3.5" = 1,137in-lb of momentum on each swashplate bearing.

Consider using Kaydon Bearing

http://www.iecltd.co.uk/bearing/products/abis/tsbrgs.htm

Lower Rotation Stop (scissors):

2 options:

1. Put bearing on end of inside lateral bolt and have the bearing run up and down in a slot, similar to the Indian. No!

2. Put scissors on the rear longitudinal. The longitudinal rod will move the mid point on the scissors and this will move the swashplate. Am doing!

May want to reduce size of swashplates

1. So rods can clear engine mount plates.

2. So they will weigh less.

They are big v.s. Ultrasport.

It looks like 0308 [uniball] could have its diameter reduced and 0270 [gimbals] cannot.

Dec 99. Am reducing uniball. It will be the swashplate.

NOTE: THE UNIBALL MUST BE MOUNTED ON A STUB TUBE SO THAT IT DOES NOT ROTATE WITH THE MAST. This is so that the ring will not rock on the uniball at 1P

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Last Revised: November 1, 2001