Static Mast

bryancobb

Junior Member
Joined
Aug 2, 2010
Messages
5,336
Location
Cartersville, GA
Aircraft
Owned Brantly B-2b/Fly Kitfox III/Mini-500b
Total Flight Time
1350
I was reading on the MD Helicopters website about some of the design details of the 500 & 600 series machines.

The idea of a hollow static mast that does not spin with the spinning rotor attached to IT at the top is genius.

Then the drive mast (which can be very small diameter) spins inside it. It is splined at the top and bottom so that it carries NO LOAD. The gears in the gearbox carry no axial load and can move up/down slightly on the splines as temperature changes. The rotor hub at the top can do the same and only the tube called the Static Mast carries the lift load (in tension).

All MRGB bearings can be radial ball type and planetary type, simple to set-up gears can be used to result in a bulletproof semi-Brantly clone .

The swashplate tilting sphere can ride up/down the O.D. of the static mast.

Great OLD IDEA!
 
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That makes sense. I have replaced many mast spacer tubes on the EC135, as the drive 'tangs' wear beyond spec. I used to use a torque multiplier to tighten the mast nut to 750 ft lbs. The new mast nut goes on hand tight, with the "12 disciples" bolts around perimeter of the nut torqued to a mere 20 ft lbs 😲.
 
bryan always seemed the way to go to me much less chance of catastrophic failure
 
Thanks Bryan,

Could you post a link as to what you were reading. I was wondering if anybody has done that in design of final drive. Nothing new under the sun.

Thanks,

JB

John 3:7-8
 
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