Correoulis effect

The so called "torque roll" phenomenon in a propeller driven aircraft is most pronounced in a small aircraft with a large engine & propeller, and at low forward speed. It is the result of two distinct effects, both arising from the propeller, plus the yaw-roll coupling that is built into any stable airplane.

First, when the throttle is jam accelerated with the propeller governor set at maximum RPM, the accelerating rotation of the propeller (clockwise as seen by the pilot) will produce an immediate left counter roll in the aircraft.

Second the helical flow of air from the proipeller around the fuselage of the aircraft usually impinges on the left side of the vertical tail, yawing the aircraft to the left. When power is increased, this effect is increased and the pilot generally instinctively adds right ruudder pressure as he advances the throttle to counteract it. Because of the roll/yaw coupling built into the airplane the right rudder pressure also counteracts the left roll tendency that cimes from the accelerating propeller.

All of these effects are most pronounced at low speed where the effectiveness of the rudder and the vertical tail are the least. Indeed on many large-engined prop aircraft the throttle at takeoff is initially advanced only part way with nearly full right rudder, -- power is increased to the maximum only as the sircraft gains speed and the rudder & tail become more effective.

Such a very strange question:)
ebrown I have a question for you since you did mention it.
All things equal; a 16" diameter tire and a 21" diameter tire are both traveling at 60mph. which one would be easier to move off its axis.

Does anyone know how I can get in touch with wilso? I want to find out if there is the same effect down under ie, more difficult to turn right then left.

As for the safe/unsafe bike, it is not a mechanical issue. The "feeling" of being uncomfortable or having more difficulty turning right is on al bikes V twins, single, twins, opposed twins, triples, v fours, in line fours, opposed 6's.... you get the idea.

I have shot this question up to "proffesional" motorcycle riders and was told it was a mental issue for the rider, however I have heard to many riders mention it.

The search continues......

ralph - try PMing him.

The issue is sensitivity. A 5 or 10 mph breeze can boost an Olympic 100-meter sprinter by .05 second and that could be a new Olympic record.

It takes very little effort to turn a bike. A half ounce assist to a bike rider would feel the effect. Don't forget on the right turn it is also fighting the slight Coriolis effect so the difference between the left and right turn is twice the Coriolis effect.

Talk,

The issue is not sensitivity-- for two reasons.

First the coriolis effect (specifically the effect of the Earth's rotation) on a motorcycle is not comparible to the effect of a breeze on a runner. The coriolis effect is much more insignificant at the scale of a motorcycle than a breeze on a runner.

But there is another reason that the coriolis effect wouldn't cause a motorcycle to "turn more easily to the right"...

Motorcycles travel in many different directions. Left and Right are meaningless in this discussion. The Earth spins from West to East, and obviously this spin would affect the motorcycle travelling North differently than it would effect the motorcycle travelling South.

If there were any science here, the motorcyclist would report that his motorcycle turned easier to the left half the time, and easier to the right the other half (unless the motorcyclist only travelled North).

If the cyclist said something like-- "My motorcycle has a hard time turning East"-- it would be a little more believable (but not much).

It doens't matter because the effect is too small anyway.

The gross weight of a North American Pursuit Model 51D, exclusive of ordnance and fuel, was 11,600 pounds. The gross weight of the Supermarine Mark V.C. SU7501 Spitfire, exclusive of ordnance and fuel load was 9,500 pounds. From what you state above, it would seem such an effect would only be noticable near stall speed, during take-off or landing. Is that so, as far as you would surmise?

Actually the driver of the motorcycle would be unable to observe any Coriolis force whatever, because he is moving with the bike. None of the steering forces would be altered at all. As e.brown noted the magnitude of the Coriolis effect would depend on the Latitude of the bike, the direction in which it was travelling, and its speed. It really isn't a "force" as such, rather a correction we must make to the acceleration, measured with respect to earth coordinates, of the moving object. The correction is needed because the earth coordinates are themselves moving due to the earth's rtotation. We call it a Coriolis 'force' only because it is needed to make the equations of motion (F=ma) balance in earth coordinates.

The term "all things equal" is ambiguous (which makes the problem difficult to answer exactly). I assume you mean a direct scale in all dimensions-- this means that the mass would change and even the diameter of the axis. This makes a bunch of other relevant changes including the amount of friction and probably other things I am not thinking about right now.

But-- the important quantity is the "Moment of Inertia". This is behind what we have been calling the "gyroscopic effect" and is the resistance of a rotating object to rotational acceleration.

The Moment of inertia is calculated (using calculus) by the sum of the mass of each particle multiplied by its distance from the axis of rotation.

In short the bigger wheel will have a greater moment of inertia if the proportion of the wheel is increased since there will be more particle at a greater distance from the axle.

I did some experimentation while showering. I have a slowish drain, so the water builds up a little before swirling down. My drain seems to be ambidexterous - it goes both clockwise and counter clokcwise, depending.

The coreolis effect would be experienced, to the extent that it is experienced, as a slight tilt of the ground coupled with a slight increase in the force of gravity. This because it adds a horizontal force to the vertical one from gravity. It is of course negligible.



In the northern hemisphere it would accelerate the bike traveling south eastward, and accelerate the bike traveling north westward. This because the bike traveling south would be moving further from the axis of the earth, and thus accelerate in velocity around the axis (accelerate eastward), while the bike traveling north would move closer to the axis of the earth, and thus decrease the speed with which it is circling it (accelerate westward). The force would not affect bikes moving east or west.

So, in the northern hemisphere bikes travelling north/south would be seemingly pulled to the left by the coreolis effect.

Coriolis' force would not be felt unless you are moving at the speed of a jet plane or a rocket.

ebrown, The reason I said all things equal is I didn't want to pull into play the whole I dea of leverage etc etc abot motorcyle rake, angle handle bar style yada yada yada. I was just looking at two tires of different diameters traveling at the same mph.

I love these discusions:)

Sorry, I should have said precession not Coriolis.

Here is something on spinning wheels of bicycles and motorcycles.

Precession

Coriolis is only an apparent force anyway. It's not an actual force.

My thought about the motorcycle thing is is that I wonder if the "force" would be different if he would be riding in the UK. Right turns and curves are going to be much sharper, right? You're usually on the right hand side. Just a silly thought. I'm probably wrong, though.

When we do this we are usually in a parkinglot, so it matters not on the sharpness of the curve. We can make them as sharp as we want.
I'd like to find a person who has ridden in both the northern and southern hemispheres to see if the feel the same "effect" in both spheres.

I actually ride a a bicycle and scooter which are slower than a motorcycle. I don't notice any difference turning left or right except maybe that the throttle grip ofthescooter is on the right hand so it is doing double duty. It could be that the inconvenience may lead one to think that the right turns are more difficult.

If you read the precession in the bicycle section it confirms the lean left turn left ease as the prevession produces a backword motion. The lean right does produce a precession forward thus hindering right turn.