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Between the Races: Cedric Lynch
December 11, 2009 by CJ
Filed under Between the Races
In late October, we posted an interview with Agni Motors CEO Arvind Rabadia, whose company won the inaugural TTXGP for electric motorcycles on the Isle of Man. Following that conversation, we also chatted with Agni engineer Cedric Lynch. We can’t say we completely understood all the technicalities of what he said, but it was a very enlightening conversation nonetheless.
Rob Barber did the riding at the TTXGP, but much of the credit for Agni’s win goes to engineer Cedric Lynch. - Paul Blezard photo, courtesy Agni
RRX: Can you explain what makes the Agni engine special?
Cedric Lynch: Rather than the conventional armature layout, it has an armature which is in a shape like a thick disc, and the magnetism flows axially through the disc and interacts against magnets which are placed by the side of it. The magnets are stationary and they’re shaped rather like disc-brake pads. In this way, the armature is interacting against two locks of magnets for a given winding arrangement, which means that it has half the speed and twice the torque, everything else being equal. And so it’s possible to regain the original speed by doubling the voltage, and that way you have twice the power at the same speed. You have a high power-to-weight ratio, and also, the proportion of the power that is lost to friction is much less than in a conventional motor.
How did you come to be involved in the electric-motor field?
There was a competition that was held in 1979, by a manufacturer of car electrical equipment. The competition was how far could you go on two of their car batteries in two hours, and I entered this competition with a vehicle that I made myself. I found that you couldn’t really buy a good DC motor for a price that I could afford, and so I made my own motor. This was a fairly conventional layout, but it used armature and field laminations that I’d cut from old soup cans that I’d opened out flat. And then there’s an organization in the UK called the Battery Vehicle Society with similar vehicles, and I went into those. I was trying to think how I could make a better motor, and I thought one of the main things I had to do was to try and use the proper electrical steel rather than the material from soup cans, because the properties ought to be a lot better. And so I thought of this design of motor in which all of the armature laminations are rectangular, which meant that they could be cut via guillotine—there wouldn’t need to be a special tool for punching them out—and I was able to buy small laminations in a small quantity at a price I could afford. And then I realized that the motor with this layout was more efficient than a conventional one—partly because of running at half the speed and twice the torque, and partly because it’s possible to use grain-oriented electrical steel and take full advantage of it because the magnetism flows on only one axis through the material instead of all directions in the plane of the material, like in a conventional motor.
Was there a big adaptation in applying your knowledge from the car field to the motorcycle field?
Not really. In these Battery Vehicle Society competitions, they started allowing two-wheel vehicles, and I built one as soon as it was allowed. For the Lucas competition, the vehicles had to have at least three wheels, but the Battery Vehicle Society competitions also allowed two-wheelers, and so I started building those. Although for this TT thing, we had to base it on a conventional motorcycle, because the normal FIM rules about racing motorcycles applied. Except they were allowing the feet-forward bikes and allowing considerable more streamlining if you used that design, but the problem was that we couldn’t find anybody qualified to ride in the TT who would’ve been willing to ride it. The rules in effect required the rider to be riding in the gasoline-powered races as well, because they had to have at least five practice laps, and the electric bikes only got two practice laps, so they had to be riding a gasoline-powered bike also, and so they all wanted something that would feel familiar to them—not something unusual. We had a rider in March, and we asked him what bike we should convert; he said a GSX-R600 or 750, because that was what he was already riding. We had to arrange to buy one without its engine in, and we fitted all the electrics into that. It worked out really well.
The team used a GSX-R chassis for the TTXGP, but Lynch would like to experiment with more aerodynamic designs. - Courtesy Agni
There were a number of disparate solutions at the first TTXGP. Do you think things will begin converging soon?
I don’t know. I expect it will eventually, but I don’t think it will immediately. I think there are still going to be a lot of different electric motors used. Our motors are brush-type DC motors, and some competitors are using AC motors with electronic commutation. I think there some people who have been competing in a series they run in Italy who are using conventional, series-wound motors like forklift-truck motors. So I think that will probably continue for some time.
How long will it take before the performance numbers are equal to those of gasoline-powered motorcycles?
I don’t think that they will equal gasoline motorcycles unless somebody comes up with better batteries, or unless they allow the electric bikes more streamlining than the gasoline-powered bikes are allowed, because the energy content of the best batteries. The best ones you can buy store at an energy density of about 200 watt-hours per kilogram, but the best that can give it out at a high rate—like 120 minutes—are more like 130-or-so watt-hours per kilogram. And that is a tiny fraction of the amount of energy which is stored with a gasoline engine.
With the amount of battery development happening these days, do you expect that to happen soon?
They’ll never reach a level comparable with gasoline, because the battery’s storing in it all the materials that will take part in the chemical reaction, and the material will remain in the battery after the reaction is finished. So it’s a bit like the equivalent of storing both the gasoline and the oxygen, and then capturing all of the exhaust gases and carrying them on the vehicle. If you were to do that with a gasoline engine, you wouldn’t have such a big weight advantage, because it has the advantage of taking part of the material that participates in the reaction from the air, and then the reaction puts material back into the air afterwards. That’s a lot of stuff that’s not carried on the vehicle, although there is a type of battery that uses air as one of the reaction components—the zinc air battery, for example—but I think it is not capable of very high discharge rates at the moment. I think there is an Isreali company that is developing those for highway vehicles, but I think it’s not capable of very high discharge rates, suitable for racing—although it will give several hundred miles on the road. But it does have the serious practical drawback that you can’t recharge it yourself, from your own electricity supply. The insides of the batteries have to be cleared out and replaced with fresh materials, which are distributed at filling stations.
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Now I better understand what’s going on with electric bikes, not that I expect them to ever be interesting for racing due to their lack of sound(exhaust noise).
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