Reverse-Rotating Rotors

I have googled & failed to find any mention of this...

http://www.motorcycle-usa.com/Article_Page.aspx?ArticleID=3207&Page=1

Quote
Inventor Robby Kasten had come up with a potentially revolutionary
design to "eliminate speed-related steering effort while increasing
stability." His idea was Reverse Rotating Rotors (RRR) which would
counteract the gyroscopic effect of the front wheel by spinning the
rotors in the opposite direction of the wheel.

My physics isn't good enough - would this work ?

Without the gyroscopic effect won't the bike fall over ?

What do folks think

 

In uk.rec.motorcycles, Mac belched forth and ejected the following:

<BUUUUURRRRRRRPPP!!>

 

I think it's been tried and made no difference at all to the stability.
Could have been Tony Foale.

 

FWIW, I reckon that as long as there's *some* precession force in the
right direction then the bike will self-balance, otherwise, as you
imply, it will rely entirely on rider input or some active system to
keep it upright, or maybe increased rake/trail would keep it stable.
I'm not sure that that would be a good thing, TBH.

The steering would become incredibly .., weird, thinking about it.

On the one hand, the natural balancing forces (as in keeping a bike
upright) would lighten considerably, but on the other, the wheel
itself would still resist being turned; the steering forces would be
reduced or even cancelled out.

Then there's the unsprung weight, which would almost certainly be
heavier.

In all honesty, it looks like a solution looking for a problem.

 

It's bollocks. Corn-fed, high octane bollocks.

The gyroscopic effect doesn't keep the bike up.

Actually, there was a guy wrote an article for Motorcycle Sport, about 20
years ago, about how he had tried something similar, but with annular
flywheels mounted inside the tyres. He expected that the gyroscopic effect
of the flywheels would keep him upright at a standstill. On his first test
ride, he came briskly to a halt after spinning up the flywheels, waited...

....fell over. Duh.

Things you'll never know.

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Champ

Whereas we all know that they only stay up due to a collective
suspension of disbelief.

--
Wicked Uncle Nigel - Podium Placed Ducati Race Engineer

WS* GHPOTHUF#24 APOSTLE#14 DLC#1 COFF#20 BOTAFOT#150 HYPO#0(KoTL) IbW#41
SBS#39 OMF#6 Enfield 500 Curry House Racer "The Basmati Rice Burner",
Honda GL1000K2 (On its hols) Kawasaki ZN1300 Voyager "Oh, Oh, It's so big"
Suzuki TS250 "The Africa Single" Yamaha GTS1000

 

I can't argue 'ignorant' or 'wanker' and I still don't
understand gyroscopic precession and is this the end of tank slappers ?

My ignorance aside - do the comments here make sense.
http://forum.motorcycle-usa.com/default.aspx?f=54&m=245375
The entry by "Magellan" at "4/25/2006 10:09 PM (GMT -7) "

(posted through google - I hope the format isn't to monged)

 

I don't think it will have any significant effect on stability. However, it
may well work in terms of reducing the effort involved in making steering
adjustments. The faster a wheel is rotating, the harder it is to change the
(geometric) plane in which it is rotating, due to gyroscopic effects. This
is very easy to demonstrate with a bicycle wheel and spindle. If one person
holds the wheel spindle at each end and the other spins the wheel rapidly
the person holding the wheel finds that it becomes very difficult to change
the angle of the wheel spindle due to the gyroscopic properties of the
spinning wheel. Steering a motorbike involves major changes in the planes
of rotation of the wheels as the bike leans over. Anything that reduces the
gyroscopic effect of the spinning wheels should make it easier to lean the
bike and easier to make any handlebar adjustments. For example, going
through an S-bend where the bike has to be rapidly moved from leaning one
way to leaning the other should require less effort and could be done more
quickly. I think the hoped-for trade-off is that any increase in weight
will be offset by more rapid progress through corners.

It shouldn't have any major effect on basic stability - IFAIK Newton's first
law keeps bikes upright "....an object in motion tends to stay in motion
with the same speed and in the same direction unless acted upon by an
unbalanced force". Although the reduced gyro effect of the wheels would
mean that less force was required to tip the bike over whilst in motion, it
also means that less effort is required to correct any tendency to fall over
so the overall effect is probably pretty neutral.


Tony

 

He'll be telling us that shaft-drive bikes can wheelie next.....

 

TMack wrote:


I've always assumed motorcycles are kept upright in motion in the same
general way you can balance a billiard cue on your finger. You move the
base around so that it stays beneath the CoG. This is pretty easy to do
when moving on a motorcycle and would be nearly an unconcious action
once learnt. This seems to be a fairly comprehensive technical
description though http://www.msgroup.org/TIP048.html

 

Here's the article about the pushbike with counter rotating disc:
http://socrates.berkeley.edu/~fajans/Teaching/MoreBikeFiles/JonesBikeBW.pdf

 

I don't think that I agree, if I let a push bike run down a hill on
it's own I expect it to fall over: and at what speed does it become
self correcting? I notice it's much harder to keep a bike stable at low
speeds than high speeds.

 

I saw video of a bike at Bonneville dry lake. The bike went into a tank
slapper and the rider was either pitched off or bailed out. As soon as
he was gone, the bike steadied up and went in a straight line till it
lost speed [1] and fell over.

[1] somewhere around a fast walk.

 

In uk.rec.motorcycles, Mo Childs belched forth and ejected the
following:

You expect wrong.

When we were kids, I remember my mate fell of his bike and in a fit of
defiance he threw it. It sat up and rolled all the way down the hill[1]
- on its own - and it stayed upright, went over the road at the bottom
and jumped over the kerb.

I remember laughing my fucking head off, it was the funniest thing I
think I'd ever seen and probably still is. I can't remember anything
that made me laugh like that before or since.

Running pace.

[1] This was in a wooded area and it had to negotiate bumps, dips and
other "woody" bits.

 

They are self correcting. The gyroscopic precession is important
because it turns the steering in the direction the bike's about to
topple, and the "cornering force" thus generated keeps the bike
upright. This is why it is so important to have good, well-adjusted
head bearings.

The steering is stabilised by the castoring effect.

 

Yes, but only indirectly: see my previous answer.

 

Cop out!

I *strongly* think you're wrong.

Imagine riding at very low speed: you generally have to manually pull
the bars back and forth to maintain balance because the precession
forces are so much smaller at low speeds.

If you think about it, the castoring effect naturally *centres* the
wheel; it doesn't provide steering input for balance.

 

I think the honourable gentleman is at least equally guilty of
religious dogma!

Steering is all-important to balance in a motorcycle, yes? If you
don't believe that, then kindly educate me as to how a bike balances.

If you don't believe that, then consider this experiment:

Try tightening you head bearings so that the steering still turns, but
with difficulty, or fit a *really* stiff steering damper.

You'll find that the bike wallows and even weaves badly at slow
speeds, but stabilises at higher speed.

Let's see what happens:

First, the bike starts to topple one way or the other, say to the
left. The front wheel precesses, turning the steering left.

Initially, because of the drag from the overtight bearing, it doesn't
react enough, so the bike topples further, causing the wheel to swing
harder.

Eventually the steering catches up with the topple (I suppose that in
control system terms it would be said to suffer excessive phase lag)
and corrects it, but it's now pointing too far to the left and in fact
has gained "yaw" momentum, which could be worsened by heavy fairings,
bar end weights, etc. Because of this, it overshoots and overcorrects,
causing the bike to roll too far to the right... and the cycle repeats
in the other direction.

At higher speeds, the precession forces are much stronger and can
overcome the damping drag, so the bike is actually more stable, up to
a point.

The castoring forces are also stronger, of course, but as I said,
these only act to *centre* the wheel, not provide balance, and there
is a speed, usually outside the bike's design range, where it *will*
go unstable.

 

Do you think that I think (IYSWIM) that it's purely a "spinning top"
effect, or a steering servo effect? 'Cos I think it's the latter.

Both my belief and yours are active steering control effects, it's
just the force that turns the steering that we're arguing about.

And I have no problem with a bike curving if left to its own devices;
again, the steering may well set to a slight offset, just like any
proportional-only controller might.

I've just looked at the initial pages of John Robinson't "Mototcycle
Tuning: Chassis", and though he talks about how a bike steers, and
thus balances in a corner, he doesn't actually explain where the
steering forces come from under normal operation; he merely describes
the effect of the steering. I'll have to read further - I bought it
years ago and never read it fully.

 

Ok, I've had a further look, and I've realised that the castor offset
*does* turn the steering in the direction the bike wants to topple,
just like the weight of a shopping trolley that's been tilted onto two
wheels will cause those two castors to swivel in the direction it's
tilted.

But the act of tipping it *will* cause the front wheel to precess in
the same direction, so in fact both forces are involved in turning the
steering; one is transitory, and only occurs as the angle of bank
increases, and it's strength will also increase with the bike's speed;
the other increases with angle of bank but I guess will be constant
WRT bike speed.

At small angles of bank, such as nearly upright, the castor steering
force will be *very* small. The precession force will not be,
especially at speed. Then again, it doesn't take much steering
movement to balance a bike that's nearly upright.

Finally, there's another force called camber force, which is caused by
the curved profile of the tyres and will again cause the bike to want
to turn into the bank. I *think* that this is a lesser force, though.