Electric Race Bike/Pulsed Power?

Wouldn't that limit power? I would think a traction control scheme would be the way to go...or perhaps a wider back tire or improved tread design for better grip...

Would limit outright power as used on the straights, but in the corners less of a problem where you are usually at less than foll throttle.

You could use a mini gyro to activate the pulse mode when the bike leaned to either side....maybe

WOW!

I think they were going too fast for the bank on the corner. Rider skill and track conditions will limit the speed.

With a perfectly banked corner for x mph the speeds could get very high. What is the object of the competition - rider skill or just absolute speed? If it was just speed then go to the salt flats and do a straight away.

You might have something there. The total force on the tire is a combination of the thrust from the motor and the cornering force. These forces are at right angles, the cornering force being towards the center of the turn and the thrust in the direction the bike is moving. The total force on the tire is the vector sum of the two.

https://www.semanticscholar.org/paper/Nonlinear-tire-lateral-force-versus-slip-angle-Koo-Tan/3f9ebcc3f9b74194721a299ab2b2ebbc9652453d/figure/0

When the total force exceeds a certain point, the rubber gives way and once it is sliding, it cannot generate as much cornering force, as shown in the figure above. The bikers want to get as close as possible to this point without exceeding it. Pulsing the thrust may give the rider a feel for how close he is to this limit by "probing" it for a short enough period of time that the rubber doesn't completely break loose.

The only time s I ever lost traction was when I hit oil on the road or water, or sand, in other words it wasn't the tire that lost traction, it was the road surface...that's the problem as I see it...now if you're giving it too much throttle coming out of a turn, that just requires learning the bikes characteristics....but the road surface is ever changing...that's a different animal...

These guys racing are really pushing the envelope. It looks like, from the video, that their leaning over about 60 degrees, 30 degrees from the horizontal. The coefficient of friction has to exceed the tangent of the lean angle. (tan(60^o) = 1.732...)

"Under good conditions, a tire on concrete may have a coefficient of friction of 1.7."

https://www.sciencedirect.com/topics/chemistry/friction-coefficient

So we have several variables involved here, the temperature of the tire which governs the stickiness of the tire, and the condition of the track surface, the amount of lateral force exerted on the tires, and the tire surface area in contact with the road...A larger tire surface would seem to be the obvious solution, but that may be limited by regulation...next would be a stickier tire surface...the track surface condition is not controllable by the riders...You could regulate throttle response by angle of incline, not sure if that would work as an advantage or not....then again you could make it quite subtle, but I would think that driving experience on that particular bike would play more of a role than tampering with throttle response...

It's like "Price is Right", the winner is the one with the highest tan(Θ) without exceeding the static COF. Not for the faint of heart!

Luge Style E-Moto Redesign

Eliminate the back end monster tire. Use a no-tread monster torus for the front tire, powered and followed by the engine, then the driver in luge posture, then two pairs of inline small diameter, small section wheels behind driver have passive angle(no rack and pinion) to large wheel and are electrically driven differentially for steering and active suspension. Use a virtual forward pointing display from two+ cameras on either side of the big torus tire to provide driver visibility. This configuration gives amazingly low CG, cannonically low forward air surface, reduced area for the double speed tire top(s), and safety advantages of legs forward and spinal column inline, all behind both the megatire and the engine. The head of the driver can be in a small, strong cage with a surround "diving platform" halo mounted stiffly from the frame so rear-ending the vehicle results in the overtaking cycle getting lofted and deflected by the active steering. The driver does not really need to "wear" a helmet since the roll bar head cage IS an integral helmet, but if one is additionally worn, it can be lower strength and softer. Full chest harness safety belting should be worn. T-bone collisions are horrible, but then, they always were. Video feed is readily available for spectators directly from what the driver sees. Remote driving is possible and drone participation races way easier than in traditional non-luge configurations.

Theories of pulsed propulsion having superior road holding can be tested with drones. Drone driving of traditional E-Moto cycles would be considerably harder.

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thewildotter

"... manufacturers have adopted the 'big bang' approach where the engine produces more distinct power pulses and then rest periods where the overworked tyre can reconnect with the pavement ..."

Any studies or decent references with information about manufacturers pursuing other than smooth power from ICE for the purpose of improving traction in the method you describe?

https://en.wikipedia.org/wiki/Big-bang_firing_order

"... Thus, the power peaks are very strong and can overwhelm the rear tire (if used in a motorcycle), but when the rear tire does slide, the temporary lull in power between power strokes generally makes the slide easier to catch....."

This does not suggest that a bike with pulsed power might enjoy better grip and cornering. It says that the peaks more easily overwhelm the tire but that the sliding tire has a better chance of catching in the lul. That means the tire is sliding at lower average applied power.

The article also doesn't suggest this would be a reason for making the power less smooth. It does sound like a desirable thing to have if burnouts or drifting are goals.

From the same article:

'... Mick's secret is corner speed, so he needs the bike to be smooth and the 180 is much smoother."[3] ...."

Review: How do antilock brakes work? See...
https://www.erieinsurance.com/blog/driving-on-ice-pump-pump
..."Antilock brakes decrease your stopping distance and increase control and stability during hard braking. It’s an especially useful feature on icy roads, where traction is limited. An antilock braking system is made up of speed sensors mounted on each wheel and an electro-hydraulic braking circuit. When used, ABS prevents your wheels from locking by monitoring the speed of each wheel and automatically pulsating the brake pressure when it detects skidding."
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Generalization:
The topic concept is just the (acceleration vs deceleration) complement of braking(ABS). "Traction control" searching might be a way to perceive the broadening and maturing of this general concept beyond braking. The OP description could be improved by including stability sensing and faster-than-human adaptation to the sensed data in addition to simple fixed modulated pulse trains('big bang' approach.)

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Judgement:

This evolution is merely a good, typical technology maturation example which is well under way and vanilla. It is, therefore, what we otter be doing and we should be considering even more extreme changes such as my luge configuration which has good cross-terms with adaptive traction control. Useful sensors are maturing in quadcopter drones and are now OTS commodities hardware wise.
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thewildotter

Antilock braking may seem like a good analogy at first blush, but consider how different it is from pulsed power in important ways:

Antilock brakes use sensors

Antilock brakes pulse at frequency designed for that purpose, peaky engines pulse at frequency dictated by engine rpm

Antilock brakes modulate the brakes at the edge of tire grip limits to retain the ability to steer. Pulse power being ascribed to cornering improvement is not analagous as the cornering force testing the tire grip limit is 90° off from the applied power pulse. To be analagous to pulsed power, it would have to be something like a system that under hard breaking (just before sliding) rapid steering inputs were applied left then right in quick succession to somehow stave off sliding (or make it easier to recover from).

Think about it, if during hard cornering (just below sliding) the brakes were applied quickly enough to make the tire begin to slide but then released, it would be easier to regain traction than when the brakes had been applied. However, it would still have initiated sliding, requiring recovery.

The Big Bang and the anti lock braking systems are both devices that were manufactured to overcome the human requests: "I want more power and I want it now" and "I need to stop and I need to stop now".

In other words they are there to tame the human instinct to grab for full power or full brake force.

And because the electric powered race bike manufacturers have not yet gone through the same development cycle as the gasoline powered race bikes have, they are now faced with the riders grabbing for maximum power from an electric motor the instant the rider feels the lean angle can take more power, but the additional problem there is that electric motors deliver all their power in the instant it's asked for and the riders simply haven't mastered how to cope with that so the makers will have to compromise on the power delivery somehow in order to smooth it out so the riders don't get pitched into the sand traps so easily.

Tame the beast too much and all interest will be lost by the audience. The thrill of watching is partly the vicarious pleasure of the challenge - without actually risking your own neck.

One of the strange things about tires and cornering in RWD cars, You keep applying power once you feel the weight shift. Then as long as the tires have traction you can accelerate and control (within limits) the vehicle. The biggest problem is push, where the front end wants to go straight. Usually that limits your cornering speed and acceleration more than you rear tires.

Obviously the physics of a 800 pound motorcycle and a 1 ton car are somewhat different, but the basics of friction vs speed vs angular acceleration will be the same at the tire level.

Now for pulsing the power output not sure if it would be the same for a bike as it is for a car. For a car hanging on the ragged edge where any change in the delicate balance of power friction resistance and balls can be catastrophic. Probably not a good idea. I know an F1 with a misfire is taken out of the race. If the misfire occurs at a critical point in a corner or pass they will lose the car. Just that momentary blip is enough to lose traction and control.

I don't know how true this is but reading the comments on some of the MotoGP boards they say the MotoGP manufacturers intentionally induce rear wheel drift by making the frame flex because that can make the time spent changing direction faster so less time is spent cornering because any time off of full throttle is time wasted.

Sounds right. Pretty much the mantra in any racing.

The best method to prevent rear tire slip is the rider.

If you are not riding on the edge of control,you are not riding hard enough.

There is a thrill in teasing the edge and prevailing when there is uncertainty in the outcome.

The rider becomes one with the machine,and can adjust for many variables.

No matter what type of control system you have, competitive riders will always ride the edge of control,and they do not always win.

Consider motocross riders for instance.

Look at all of the constantly changing track conditions that change every lap,and the rider must adapt in an instant.

2 stroke engines were once the dominant engine type,and the power was very peaky,not smooth by any stretch of the imagination,but they adapted to it.

Now 4 stroke engines are dominating the motocross tracks,they have smooth power,and this is the preferred engine now.

They are much easier to control,and they have become as light as the 2 stroke engines.

Smooth power is the way to go.It is predictable and easier to control.

One less variable to worry about.

I would expect GP riders would feel the same.