Motorcycle aerodynamics, a slippery and windy, slope?

[Frank Lee]

P- P- P- Poetry!

[sendler]

Sorry to go all mushy. I am in the middle of winter and haven't been able to ride for six weeks. Then, yesterday, a friend that happened to buy a new Ninja this summer came over and we stood around looking at every detail of my Honda for two hours. And not riding it. Then I decided to wash it and apply the CorrosionX treatment I have been wanting to use. Rode it 400 meters down to the car wash and back. Was blowing off the water but some of the drops on the windshield were solid. I am in withdrawal.

[Frank Lee]

Understand it... I think even more so on bicycle.

[user removed]

Stayed in the house all day yesterday, 0 fuel.
Rode my CBR 40 miles today, got to 56 degrees at 3 PM, .5 gallon.
Supposed to hit 59 tomorrow. Maybe I'll take the Vulcan.

Tuesday-59
Wednesday through Monday 52,52,57,52,47,47.
Some clouds, no rain.

815 miles in January, maybe I'll beat that in February.
About 13 gallons in gas.
$42

regards
Mech

[Ken Fry]

Originally Posted by Frank Lee

P- P- P- Poetry!

Max Headroom! I'm always amazed when I can remember faces and names.

[Ken Fry]

Originally Posted by Old Mechanic

Tuesday-59
Wednesday through Monday 52,52,57,52,47,47.
Some clouds, no rain.

It's been pretty springlike here too. 61 tomorrow.

[Electictracer]

[QUOTE=Ken Fry;285097]1. The issue can be seen by watching someone start out on an Ecomobile or Monotracer. Unlike a motorcycle, which the rider naturally makes vertical with respect to gravity at a stop, enclosed motorcycles (so far) list at a stop to be perpendicular to the road, which is typically crowned. So the driver has to first get the wheels directly under the CG, which requires a swerve. If the bike is leaning to the right, the driver must steer to the right. If there is a car immediately to the right, this is a problem.

In a normal motorcycle, this stuff is so easy that it requires no thought and almost no effort: even if you are leaning slightly at a stop, a tiny push to vertical is simple.QUOTE]

This is very insightful. I wish I had read this about 6 months ago.
My plan with my outriggers is to have torsion springs with an air shock holding down the wheels. The start out lean would be less dramatic this way, then say if your wheels where 1 inch off the ground when straight up. The crown in the road is something I did not consider. I can see the difficulty in correcting this lean on start out. It will be interesting to how big a problem this is.
Oregon commuter is the thread name for project if interested.

[user removed]

Originally Posted by Ken Fry

I hadn't remembered Keith Code calling countersteering rubbish. Ironic. He has led the charge to promote the understanding of steering a bike for several decades, I'd guess. His "no BS" bike provides a good demo of the futility of trying to corner without counter steering. As he points out, even the Wright brothers understood the concept.

Superbike School :: No B.S. Machine

I read the link and yesterday I tried the gentle push on the inside bar with only one hand, the other was not touching the bar. Of course the bike counter steered. I guess I picked it up because it is about the only way to change direction, but I think I can explain the effect, maybe better than he did.

It goes back to the toy gyroscopes some of us played with when we were children, and the same effect that was used to guide torpedoes in the old days.

When you place one of those spinning gyroscopes on a string and lean it at an angle other than true vertical, the string bends in the opposite direction the gyroscope is leaning but the gyroscope will stay in that position and not fall over. I think they call that centripedal force.

I have always wondered if it could be used for propulsion but that's a different topic. With the front wheel turned, even very slightly in relation to the rear wheel you have the two wheels acting as gyroscopes and their centripedal forces are no longer on the same axes. This creates the same push effect as the gyroscope does on the string, but the gyroscopic effect of the wheels maintains stability on the bike.

In fact if the bike had a gyroscope spinning in it at high speed, when the bike itself was stationary, you would not have to put your feet on the ground to keep it from falling over, I know this would work when the axis of rotation of the gyroscope is vertical. I believe it would work if it was horizontal but perpendicular to direction of travel. I know it won't work if the axis is in the same direction as the bike would be moving if it was moving.

Maybe countersteering should be called centripedal steering.

Centripetal force - Wikipedia, the free encyclopedia

regards
Mech

[Ken Fry]

[QUOTE=Electictracer;285171]

Originally Posted by Ken Fry

1. The issue can be seen by watching someone start out on an Ecomobile or Monotracer. Unlike a motorcycle, which the rider naturally makes vertical with respect to gravity at a stop, enclosed motorcycles (so far) list at a stop to be perpendicular to the road, which is typically crowned. So the driver has to first get the wheels directly under the CG, which requires a swerve. If the bike is leaning to the right, the driver must steer to the right. If there is a car immediately to the right, this is a problem.

In a normal motorcycle, this stuff is so easy that it requires no thought and almost no effort: even if you are leaning slightly at a stop, a tiny push to vertical is simple.QUOTE]

This is very insightful. I wish I had read this about 6 months ago.
My plan with my outriggers is to have torsion springs with an air shock holding down the wheels. The start out lean would be less dramatic this way, then say if your wheels where 1 inch off the ground when straight up. The crown in the road is something I did not consider. I can see the difficulty in correcting this lean on start out. It will be interesting to how big a problem this is.
Oregon commuter is the thread name for project if interested.

I'll post a note here (and on your Oregon thread) I sent to Visionary, who asked for driving impressions, etc. It highlights some of the issues to consider:

Hi Pete,

Looks like a pretty cool project! My main caution is that the vehicle should be vertical with respect to gravity when you come to a stop. The common alternative (perpendicular to the road surface) usually means that the bike is leaning when stopped (itself a little odd feeling) and so you must swerve to get the contact patches under the CG. This takes Monotracer drivers a while to learn, and even then, they still swerve and wobble, using up road space that might not be available.

I didn't spend a great deal of time on linkages before deciding to go with three wheels (just drive it like a car) but found that even with the outriggers deployable independently, it was hard to get the leverages right to permit both quick deployment and enough force to have good control if the vehicle started to lean too much. If the system were powered (as in power steering, with good force feedback) then this would not be an issue -- just have the outriggers reflect foot position.

My outriggers had casters for wheels, so that as they moved toward and away from centerline during balancing they did not create large drag, the way a forward facing wheel would. On the Ecomobile system, for example, tilting right and left (if possible) would cause a lot of tire scrub (which hydraulics could overcome, but human power could not).

You will need to be able to adapt to the situation in which there is a four inch deep pothole right where you need to have an outrigger (or in the path of an outrigger as you start to move).

I thought the idea of having feet come out the bottom was potentially unsafe, (as well as less than ideal aerodynamically) but it might be a simpler way to deal with balancing when stopped.

I'm an old roadracer, and familiar with countersteering, and I understand the physics of driving like a car with the outriggers down (steer right to go right) and driving like a motorcycle with the outriggers up (steer left to go right). But in actual operation of the vehicle, I found I could get out of synch. My seat was very low (6") off the ground, so roll inertia was low, and as a result the response time to control inputs was short (the roll rate was pretty high). Crashed once by getting out of synch -- kind of like the pilot induced oscillations that can happen with airplanes, especially during landings -- in my case right left right left right left boom.

I have not driven a Monotracer, but if you can find one, doing so would be helpful, I'd think.

That's about all I can think of right now, but if you have questions, please ask... and I'll try to respond more quickly. Actually a better address is ken@zingcars.com.

Regards,
Ken

[Ken Fry]

Originally Posted by Old Mechanic

It goes back to the toy gyroscopes some of us played with when we were children, and the same effect that was used to guide torpedoes in the old days.

The effects of gyroscopic procession and simply steering the contact patch out from under the CG are interrelated in motorcycle control. (And they both work in the same direction: turning the bars to the right causes the gyro effect of the front wheel to lean the bike to the left, and repositioning the contact patch does the same.

There have been studies that separate the relative "strength" of the two effects, and generally the direct countersteering effect is stronger than the gyroscopic effect. However, at very high speeds, the gyroscopic effect is quite strong. Interesting that it works that way, because that seems pretty safe -- when you are going really fast you don't want twitchy handling.

The Lit system is pretty slick and complicated, but I wonder if a simple stop stabilizing system might be the way to go with an enclosed motorcycle. The gyro would gimbal freely ordinarily(to permit steering and banking), but would be locked in place at stops. Then if the gyro control system fails, you just fall over at near zero speed. With the Lit, the gyros are in control at speed, so you'd want to be darn sure the control system is working right.