REFLECTOR: Brake performance

[Laurence Coen]

Brian,

A 600x6 is 18" in diameter for a 9" radius.  6" diameter wheel plus two 6" sidewalls.  The RG has a smaller tire that is 15" diameter and a 7.5" radius.

Larry Coen
N136LC


From: Brian Michalk 
Sent: Saturday, March 16, 2013 10:26 AM
To: Velocity Aircraft Owners and Builders list 
Subject: REFLECTOR: Brake performance


I just looked up the Matco specifications for the WHLW600XTE
http://www.matcomfg.com/WHLBRKASSY600X6TRPLeXtraTorqueEnergy-idv-3801-4.html

I don't know how the number match dimensionally, but I assume a 6.00-6 wheel has a six inch radius?

Assuming the wheel above, a 5/8 bore master cylinder and their specs of:
      Static Capacity 1860 LBS 
      Load Limit 5580 LBS 
      Maximum Accelerate/Stop Kinetic Energy 450500 ft-lb 
      Torque Rating (@450 PSI) 6441 in-lb 

For 450 PSI, I would need to press on the master cylinder a force of 138lbf, which I am certainly capable of, and feel that I can generate this much force without too much effort.  There is perhaps a 3X mechanical advantage in the pedal arrangement.

Their torque rating, with the wheel above shows that it could provide 1074lbf to a wheel weighted to approximately 750lbf.  Horizontal force is higher than vertical force, indicating a friction number greater than 1.0 is needed.

This tells me that with very little effort, one should be able to lock up the wheels while taxiing in their airplane.  I have the original brakes, the W600XT, which have identical torque performance, but different kinetic energy numbers.  I don't need higher energy, I want better torque.  I do not think I am getting the performance indicated in these specifications.  Is my math wrong?



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