Re: [ST] Counter Rotating Brakes

["Emile Nossin" <Emile@xxxxxxxxxx>]

>From: Sprint ST
>Several, maybe just one, guys have implied that if this gismo works that
>steering at 100mph+ would be as light as 20mph.  Unless the laws of physics
>have been repealed, somehow, someway all that momentum of 4-500lbs of bike
>traveling in one direction has to moved to another direction.

Well, how does the momentum of the bike if you want to push it over to the
left or right (just for the discussion), change when you are traveling at speed
(seen from the rider point of view!)? It's still 250 kgs (weight) and it still has
to fall over the same distance (arm) towards the lean, so isn't that the same 
momentum (=weight x arm)?

>I would sure like to see the numbers to prove how such a reduction in applied
>force is achieved.  Not implying that it won't but it sure sounds like a free lunch.

Well, I think I was the one that implied (as an example) that the force
would be the same at 100mph as 20mph (and also added the "or so"). But
the actual performance claim on the site is this:
"A motorcycle equipped with reverse rotating rotors can change
lean angle as easily at 180 m.p.h. as it can at 20 m.p.h"

The disc brake is lighter in weight than the wheel itself, but that's
why they let it turn at a higher speed in order to gain the same precession
force, but then turning opposite.

This technology is not new, so let's see how other vehicles have
benefitted from it, like the Russian attack helicopter KA-50 "Black Shark":
http://www.airforce-technology.com/projects/ka50/
"The coaxial-rotor configuration results in moments of inertia values relative
to vertical and lateral axes being between 1.5 to two times less than the values
found in single-rotor helicopters with tail rotors. Absence of the tail rotor
enables the helicopter to perform flat turns within the entire flight speed range.
A maximum vertical g-load of 3.5 combined with low moments of inertia give the
Ka-50 a high level of agility."
More here: http://www.gyrodynehelicopters.com/coaxial_benefits.htm
"The flying qualities of the coaxial are such as to permit high disc loadings
without affecting controllability and fuselage design; thus permitting increase in
lift capability without materially affecting the envelope of the vehicle."
"Freedom from Control Cross-Coupling: Control cross-coupling exists in all other rotor
configurations, causing control complexity, dangerous flight attitudes and vibration."

So remove the precession influence and you've suddenly simplified motorcycle
steering a lot, resulting in the ability for much higher control input without
adverse effects and with less effort.

>It seems that the discussion to date implies that force required to initiate
>and maintain the turn is the force required to overcome the gyroscopic
>action of the front wheel assemble.  You guys can correct me but it seems
>there is a lot more to getting the bike to turn than overcoming gyroscopic
>action.

Not so much to maintain the turn, it's more about the process of getting
towards the lean angle (initiate if you like). After you've turned the
handlebar (with or without precession resistance) one way, the bike leans
itself by simply falling over the other way. Gravity at work, that's how
you get a bike to lean. Once in the lean and once the frontwheel is turned
in the direction of the turn again it's a balance of gravity and centripetal
force keeping it there, although precession and trail will try to upright it.
That's about it really... I think.

You just help the bike fall over, plus you're overcoming the precession
force that resists it. You might feel like you're handling all that
weight yourself, but it's more like artificial feel. Makes the macho
and ego factor a lot less, doesn't it? :-)

Emile
www.piloot.com

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