REFLECTOR: The law of conservation energy.

[Andy Millin]

I was reading this and wondering what "Geek" would go into such detail.
Then I saw it was you.  :)

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Brainard, Jerry
Sent: 03-18-2008 1:39
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: The law of conservation energy.

I think there another huge difference.  That's the stiffness of the caliper
assembly.  The mass of the rotor does not appear to be enough different to
account for the braking difference.  If it were just the mass cooling of the
rotor, it would be a brake fade problem.  That does not appear to be the
case.  The Matco's seem to be weak in initial and extended braking.  As you
pointed out Larry, the arm is not the important difference, it should be the
amount of the heat absorbed and dissipated.  Of course all of that assume
that you have correct pad contact.  The Matco's do not appear to have
sufficient strength across the caliper.  The beautiful piston side looks
plenty strong, but the same cannot be said of the opposite side.  The bolts
might be enough, but the backing plate looks to light weight to stay in
contact as pressure increases.  That would lead to a hot spot on the inside
edge that would quickly lose braking effectiveness due to gasification of
the hot spot.  If you look at other braking systems, they have a more robust
caliper on both sides of the rotor and a very stiff junction between the two
side.  The objective is to keep both pads in even pressure on the rotor.
Obviously, it would take a brake dyno and some creative testing to confirm
my hypothesis.
 
- jerry
 

________________________________

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Laurence Coen
Sent: Tuesday, March 18, 2008 1:05 PM
To: Velocity Aircraft Owners and Builders list
Subject: REFLECTOR: The law of conservation energy.


Any vehicle, (plane,train, auto) that uses friction breaks to stop converts
kinetic energy, (speed x weight) to heat.  Therefore, Cleveland or Matco,
the same plane at the same speed will make the same heat.  Why then do the
Clevlands stop better than the Matco?  The Clevlands larger diameter disk
provides greater braking torque for the same friction due to the longer
moment arm but the increase in diameter also increases the surface speed at
the same wheel rotational speed and therefore the same heat (no free lunch).
The larger disk has two things going for it.  A larger thermal mass to
absorb heat and greater surface area to reject heat.
 
Larry Coen
N136LC
SE/RG Franklin/IVO, Stops fine Matco

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