Motorcycle aerodynamics, a slippery and windy, slope?

[godscountry]

A rudder would be interesting,using sensors,when side winds start to upset stability add a little rudder,ha ha,but it could work.Side winds are not such a big deal,a long wheel base gives the enclosed bike added stability plus it reduces the effect of side winds.Also by playing with front end settings,can further reduce the effects.Lit motors will use a gyro to hold bike up,they could write software to add more gyro when the bike is hit with a side wind,i guess time will tell.It would be nice to open source a enclosed motorcycle,a long the lines of the streamlined electric,using a gas engine,chromemolly tube chassis,full body with doors and retracts for stopping.I'm surprised Honda or ? haven't built one.The thought of traveling in comfort,safety and the fun of a motorcycle,passing petrol stations ,getting 200mpg is hard to resist.

[godscountry]

it would be interesting to see how much the wheel base affects side wind control.I'm pretty sure it could be worked out,to the point of not being a big issue.

[Ken Fry]

A rudder would be interesting,using sensors,when side winds start to upset stability add a little rudder,ha ha,but it could work.

The Ecomobile was available with a rudder.

It would be nice to open source a enclosed motorcycle,a long the lines of the streamlined electric,using a gas engine,chromemolly tube chassis,full body with doors and retracts for stopping.

The Monotracer (brother of the etracer, which I'm guessing is the electric you are referring to) uses a gas engine. It's not open source, though.

Gets 53 mpg at a constant 75 mph.
http://monotracer.peraves.ch/press/p...tracer1-12.pdf

My Zing started off on two wheels, but I decided to make it three so that it drove like a car. Like the Monotracer, mine was touchy about the transition from outriggers-down to outriggers-retracted. OK for enthusiasts, but not so good for a mass market. The Etracer fell over on the banking at the Auto X Prize and they had a hard time getting it up and rolling again, I heard.

The Lit could solve the low speed problems that come from having to first steer like a car (turn the handle bars to the right to go right) when the outriggers are down, and then steer it like a motorcycle (countersteer right to bank left) when the outriggers are up. I came up with a steering system for mine to avoid some of this, but it didn't completely cure the problem.

But nevertheless, these things can be fun to ride.

[godscountry]

Originally Posted by Ken Fry

The Ecomobile was available with a rudder.





The Monotracer (brother of the etracer, which I'm guessing is the electric you are referring to) uses a gas engine. It's not open source, though.

Gets 53 mpg at a constant 75 mph.
http://monotracer.peraves.ch/press/p...tracer1-12.pdf

My Zing started off on two wheels, but I decided to make it three so that it drove like a car. Like the Monotracer, mine was touchy about the transition from outriggers-down to outriggers-retracted. OK for enthusiasts, but not so good for a mass market. The Etracer fell over on the banking at the Auto X Prize and they had a hard time getting it up and rolling again, I heard.

The Lit could solve the low speed problems that come from having to first steer like a car (turn the handle bars to the right to go right) when the outriggers are down, and then steer it like a motorcycle (countersteer right to bank left) when the outriggers are up. I came up with a steering system for mine to avoid some of this, but it didn't completely cure the problem.

But nevertheless, these things can be fun to ride.

I was refering too the streamlined electric on Youtube,just type in streamlined electric.It's a real nice study in design,it using retracts,which is the most cost effective as of now.I like the simple CM tube chassis verse's the Monoque [monotracer,etracer] chassis.The gyro on the Lit motor design,i'm guessing would be software controlled,otherwise it would seem to me to be impossible to control,but I guess time will tell.There's a big market waiting for a user friendly enclosed motorcycle,loads of people who would have never considered a motorcycle,will want one.It's just a matter of time.

[Ken Fry]

I was refering too the streamlined electric on Youtube,just type in streamlined electric.It's a real nice study in design,it using retracts,which is the most cost effective as of now.

The MK5? -- Yes it's nice. On mine, the outriggers were independent so the bike could be held vertical with respect to gravity. Otherwise the list is uncomfortable on a lot of crowned roads, at intersections with side hills, etc. Makes the startup swerves more dramatic, as you try to get the wheels back under the CG.

The gyro on the Lit motor design,i'm guessing would be software controlled,otherwise it would seem to me to be impossible to control,but I guess time will tell.

Yes, as far as I know you're right. There are actually two gyros, so they need to be actuated in response to driver intention, which is not a trivial exercise. It is unlike a plane in which the autopilot can fail and you have manual control as a backup. So you'd need a lot of redundancy. Cool idea... dunno if I'd trust a Segway at 60 mph, though.

[3-Wheeler]

Originally Posted by redyaris

sendler
For your own safety, read this artical;

Countersteering - Wikipedia, the free encyclopediaen.wikipedia.org/wiki/Countersteering

I'm glad you pointed out the article on counter-steering.

Cycle magazine, many moons ago, pointed this fact out in an excellent article published during that time.

Well, quite surprisingly, many people wrote in to the magazine, explaining their disgust and reluctance to believe such heresy. Even superbike school training instructor Keith Code wrote to the magazine, and basically said the article was rubbish.

Cycle published another article that explained the art of counter-steering in enough detail, that even Keith Code had to somewhat sheepishly appolize to Cycle for his earlier comments.

Thanks redyaris for the link!

Jim.

[Ken Fry]

Originally Posted by 3-Wheeler

Well, quite surprisingly, many people wrote in to the magazine, explaining their disgust and reluctance to believe such heresy. Even superbike school training instructor Keith Code wrote to the magazine, and basically said the article was rubbish.

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

[redyaris]

Originally Posted by Ken Fry

Good description.

Yes, most bikes are self-correcting. A gust causes the steering axis to translate away from the wind side. (The gyro effect of the rear wheel tends to restrain the bike's rolling more than it prevents the frame from yawing, because of the leverages involved. The frame yaws, and the steering head translates.) The contact patch, due to trail, is behind the extension of the steering axis. Therefore, in a crosswind from the left, the steering axis moves slightly to the right. The contact patch is then slightly to the left of the steering axis, meaning that the bike is steering itself to the right. This banks the bike to the left, into the crosswind.

You can take your hands off the bars entirely, and this feature works just fine (provided you don't have a bike prone to tank slappers)

If you really freeze your muscles and clamp onto the handlebars with a death grip, you can defeat this built-in trait. Taking the weight off the grips by tucking and putting your chest on the tank makes the effect more pronounced.

On some bikes, cranking in a lot of steering damper will interfere with this self- correction, and the bike will tend to wander.

How does the bike know how much to counter steer?
How does the bike know how hard the wind is pushing it?
At what point does the bike stop countersteering?

Without rider steering input in a cross wind the bike will role in the direction of the wind force and follow a long arc trejectory in the direction of the wind force. Prosesion at the front wheel on its own is not enough to get the bike to roll into the wind. Rear wheel prosesion only influences to rate of roll of the bike in the diriction of the wind force.
Without rider steering input in a crosswind the bike will not find the angle of lean into the wind nessisary for the bike to follow a staight trejectory along the roadway.

Motorcycles are not self correcting

[sendler]

Originally Posted by redyaris

How does the bike know how much to counter steer?
How does the bike know how hard the wind is pushing it?
At what point does the bike stop countersteering?

Motorcycles are not self correcting

Well, we have obviously hit your nerve on this topic. I'm not sure why anyone would feel so adamant about this but any way. I am not a suspension designer but I can tell you this from riding 6,000 miles this year. Most of it on relatively straight divided highway at 65mph and often in side wind conditions. My motorcycle is very noticeably self correcting in side winds. I could demonstrate this to you "no handed" by laying on the tank and momentarily letting go. But you have to lay on the tank while riding to get the best effect which most people find self conscious or uncomfortable. Other riders suggest "riding with your knees" to take the weight and stiffness of your upper body off of the handle bars. This helps free up the steering but doesn't work quite as well. Maybe this is why you haven't personally ever noticed it.
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If your upper body is sitting high and free from the bike as most people do, it will spoil the effect that the steering geometry has to roll the motorcycle into the side wind. Cross winds pushing on the side area of the bike/ rider/ luggage that is above the center of gravity of the roll axis will cause the bike to lean over and actually turn off line the wrong way. Worse yet, blowing the rider's head and torso to one side of an upright, yet comfy riding position of a standard bike, pushes the rider out of position from over the balance line which has made the system lean and turn the wrong way. The next thing that probably happens is that the rider will try push their upper body back over the bike against the wind with their far side arm which applies a counter steering manuver to the handle bars. The wrong way. Which makes the bike lean the wrong way even further. All of this happens in a domino effect very quickly, blowing you off line. If you sit up.
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Super Sport bikes with their ultra low and narrow clip on handle bars place the rider in a better position to avoid all of this in the de facto riding postion they impart by lowering the rider's upper body, and so, the side wind center of pressure. And further, reducing the leverage that the side wind has to push the rider's upper body off the bike. My CBR250R offers the best of both worlds with high, wide bars for sitting up in traffic, and, perfect ergonomics to lay down on the tank to get out of the wind in order to let the suspension use it's trail to lean the bike into the wind.
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To answer your questions:
Motorcycle dynamics of turning and balance are very complicated.
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Bicycle and motorcycle dynamics - Wikipedia, the free encyclopedia
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Motorcycles have trail. The contact patch of the front tire is behind the steering axis. When the side wind pushes the whole bike to the right, the contact patch is stuck to the road behind the steering axis. The steering axis, which is in front of the patch, is free to move to the right more than the contact patch which is stuck to the road. The wheel has just torqued and steered to the right. Which causes a counter steering lean of the bike to the left through the combination of gyroscopic precession leaning the the wheel,
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Precession - Wikipedia, the free encyclopedia
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and the tire steering out to the right from under the cg on the roll axis which stayed where it was.
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Camber thrust - Wikipedia, the free encyclopedia
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Cornering force - Wikipedia, the free encyclopedia
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The motorcycle has just leaned to the left into the wind. Automatically. The same as if you had consciously pulled on the right handle bar to initiate a counter steering maneuver. If the center of pressure of the side area of the rider/motorcycle is below the cg of the roll axis, this would also tend to lean the bike into the wind. Or at least stop the distribution of the wind pressure from fighting the roll force of the counter steering trail if the wind pressure is at least neutral to the cg.
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Trail also tends to make the bike stand up from a lean. When the bike leans to the left, there is an increasing vector of gravitational force pulling on the left side of the bike. To the side of the steering axis. Which is again free to move more than the patch. Causing a counter steering torque to the left which makes the bike lean and steer it's tires back under the bike until it is upright again.
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The more the bike leans, the less area is presented to the side wind and, the more gravitational force is applied to the trail to make the bike stand up. Careful design has made a nice balance in the amount, and vertical distribution of the side area of the CBR250R, and the amount of trail, in order to balance the forces so the bike "knows how much to lean" into a side wind.

[redyaris]

Sendler
I do not dispute any of the effects that you referance and discribe.
What I am disputing is that they are enough; on there own, to get the bike to roll into the wind.
It is my position that without rider input the bike will not roll into the wind.