Electric motorcycle race in Isle of Man TT

[EVguru]

I just spent over an hour on the phone with Azhar Hussain, the man behind the TTXGP project.

A few quick snippets;

An ACU National licence is likely to be required.

They are trying to arrange special transport to get teams to the IOM, so that they don't have to book in advance (like right NOW!). This will be at cost. Acommodation would still have to be arranged in advance.

Bikes in the open class will have to be offered for sale at the end of the event at a set price (£20-30,000 TBD).

[Jeremy]

I understand the rolling resistance/aero drag issues well enough, Paul, and accept that bigger bike tyres don't seem to be supplied in high modulus compounds. Smaller ones do seem to be available with a reasonably high modulus, low hysteresis, compound though. They are aimed at the "big moped" category really, so may not be up to this requirement.

I'm also aware of the regen/rear wheel lock up potential problem, but would plan to limit maximum regen to no more than perhaps 30%. I have a couple of other ideas up my sleeve that would allow full regen with no rear wheel lock up risk, but need to do some more research before I go public on here with them.

Weight wise I think no more than 100kg would be a reasonably aiming point. Ideally a bike weight of maybe 75 to 80kg would be good, but is a tall order using a conventional converted bike. Again I have an idea about getting the weight down further, but won't embarrass myself until I've done some more homework.

The compulsory sale clause is a bit of a put-off. If I were to invest the time and money in an open class entry then the very last thing I'd want to do is sell it after the race. I can't see the point in this at all, it's bound to really demotivate a number of private entries.

Jeremy

[MalcolmB]

My first reaction was the same when I read the requirement that bikes must be available for sale, but is that not intended as a way of setting a limit on financial investment in the bikes, to give amateurs a chance?

[Jeremy]

I hadn't thought of that, Malcolm, but you may well be right. I'm not sure that it's the best way to achieve this objective though, as the "money no object" crowd will just take the hit, I suspect.

I'd love to see a limited budget, private entry, category that would encourage innovation from the smaller one-man-band experimenters. From all that I've read, most innovation seems to originate from individuals who think outside the box and come up with something novel and effective. These are often the sort of people who won't attract big backers and probably won't want to join a bigger, cooperative, effort.

Maybe it would help if we suggested some alternative ways to limit expenditure on entries I certainly wasn't planning on spending anywhere near £20,000 on an entry, anyway!

I've just finished doing some sums on a possible lightweight approach, but it looks like heat will be the problem. My idea was to see if a dual hub motor bike would be viable, using readily available parts. Although it's possible to get to about 65mph with a double Crystalyte 5302 set up, it means putting around 7 or 8 kW into each motor, which will cause it to overheat. The advantage of this approach was two fold. Firstly it would allow more frame space for batteries, plus it got rid of the drive train weight (but added a fair bit to the wheel weight). Secondly, it would allow full regen braking on the front wheel, so maximising energy recovery and perhaps allowing smaller, lighter brakes to be used.

The frame was going to be entirely novel, a lost foam glass/carbon/epoxy composite monocoque (but not faired, so as to stay within the streamlining rules). I've used this technique a fair bit and it is a really quick way to make complex shapes, you just carve up extruded polystyrene, cover it in composite, lightly vac bag it, then dissolve out the foam with solvent after everything has cured. The idea would be to make what amounted to a hollow tub for the centre frame, seat etc, with moulded in hard points for the rear swing arm, monoshock mount and front steering tube. A few initial calculations suggest that I could get the bare frame weight (less swing arm, monoshock and forks) down to about 6kg, with the added advantage that the battery cases would be built in.

I've been looking at high end downhill mountain bike components, as these are light, yet adequately strong for the weight. They are rated to withstand high shock loads, albeit at a lower all up weight, so should be OK for this application. Using these parts opens up the possibility of using low rolling resistance tyres of around 2.5" section - very narrow by bike standards, I know.

All told, it looks as if my optimistic target of 75kg empty weight is quite easily achieved with this approach, if only I could find some better hub motors.

Jeremy

[MalcolmB]

Definitely thinking outside the box there. I think you just threw it away Jeremy I like the idea of the lost foam composite monocoque. I'd like to see how you build one of those.

I think the compromises you would have to accept in handling and rotational inertia might outweigh any benefits of using hub motors. If I've understood things correctly hub motors also tend to be built a good deal heavier than a similarly rated conventional motor in order to develop sufficient power, so you would be paying an additional weight penalty

If you're looking for a really lightweight solution how about using a Plettenberg Predator (http://www.plettenberg-motoren.com/UK/Motoren/aussen/Predator/motor.htm)
11 kW from a 1.5 kg brushless motor! As you probably know, one of the members on the Endless Sphere forum uses a similar, but much lower powered motor with a timing belt reduction on his recumbent trike. He reports excellent results without any overheating problems. You would really want two of them, but then controlling them becomes difficult.

[Jeremy]

Thanks for the reminder about those big model motors, I'd forgotten about them as a possibility.

They need a fairly low voltage as I recall, primarily because high voltage brushless/sensorless controllers are fairly rare beasts and only available up to around 60V.

Still, the motors have a pretty high kV, so speed wouldn't be a problem, even with the low system voltage. Motor efficiency seems high, but then this will be offset by the higher overall losses from running higher currents due to the low voltage, I suspect.

I still like the idea of two wheel drive, so may give some thought as to how something like one of these motors could be mounted externally on the forks/swing arm. It wouldn't look too neat, but would have the advantage of simplifying the drive train and providing good cooling to the motor.

I think I'll have to pay more attention to the RC motor thread on the ES forum!

Jeremy

[EVguru]

Jeremy, you really are thinking along unique lines. Your proposed machine is not much heavier than the battery packs that other teams think necessary!

There is likely to be a minumum qualifying speed requirement.

They are considering abandoning the 1956 FIM streamlining rules (there is a very fast electric EcoMobile out there that wants to run) or having a seperate class.

The requirement to offer the bike for sale is indeed to limit the budget. You can always fake receipts and spend over the budget, but someone could call your bluff and buy the bike for the fixed price. In reality no bikes may actually be sold.

I'm hopefully seeing Azhar tomorrow after the rules meeting (which just happen to be being held in Luton), so I may be able to provide more information.

[PHEV]

What a strange idea to be forced to offer your bike for sale. Are there any precedents for this in the racing world? Although I wouldn't mind myself, I can think of any number of reasons why teams wouldn't want to sell thier entry (secrecy not least, many teams may be racing in order to get a product to market later down the line, and be forced to part with all thier design secrets?)
Look forward to hearing more, good luck with the meeting.

[Jeremy]

If they are going to allow streamlining, then that makes the very light monocoque a definite contender, as it wouldn't weigh any more if it were streamlined. Top speed would increase too. At the moment it's the power requirement to maintain a reasonable speed on the hills that is the limiting factor, top speed just happens to be that achieved by a non-streamlined bike with that power.

The only snag I can see by streamlining such a light design is that it will almost certainly result in a need for a couple of gears, due to the wider speed range. I'm thinking of ways to try and eliminate the gear change requirement by using some non-mechanical means, like changing the motor kV by switching the windings from star to delta. This might be enough, as it would effectively give a 1.73 ratio change just by throwing a three pole, double throw, contactor.

Jeremy

[MalcolmB]

eliminate the gear change requirement by using some non-mechanical means, like changing the motor kV by switching the windings from star to delta. This might be enough, as it would effectively give a 1.73 ratio change just by throwing a three pole, double throw, contactor.Jeremy

Very elegant. I was thinking along the same lines last night. Since RC brushless motors are so light you could afford to carry two of them with different windings, one for low speed and one for high speed. Much more complex than your solution though.