2011 Greenpower racing season

[bobc]

As per the title - we're at Silverstone (no less) tomorrow, in 2 races - the "season opener" and the "Corporate challenge".
The greenpower race series is a national race championship where schools build and race electric cars. All the cars use the same batteries and motor and compete in endurance style races at race tracks around the country culminating in a national final in October at Goodwood. The schoolkids learn about building stuff, application of science and have days out racing - it's been a very enjoyable hobby helping a local school team (Sandbach high school for girls).
More info on http://www.greenpower.co.uk
There is a very similar US series. The UK series has been going since 1999 and there are now well over 400 teams involved. At the corporate challenge tomorrow there are also teams from Bentley, Prodrive, Jaguar-land rover and a visiting team from the University of Silesia in Poland.
There used to be a "live timing" site on the net which tracked the runners in real time, but it may not be working now. The main race starts at 1.00 pm UK time
Anyway our cars are Zebedee and Brian (1st & 4th in last years championship) but there have been big rule changes so it's all very open! - I'll post how we get on after the race ;^)
http://www.greenpower.co.uk/gallery/photo.php?id=001194
http://www.greenpower.co.uk/gallery/photo.php?id=001213
stop press - there is a live timing site - it might work (it has generally been flakey in the past)
http://www.bbk-online.net/gpt/

 

[bobc]

Said I'd post - we were rubbish - silly errors, things that should have been checked & the fact that a couple of the corporate teams upped their game considerably! But we had an excellent day & left with lots of new ideas to try. To be honest I think we'll improve a lot in the next few races - doesn't hurt to have a rude wake up call every now and then! Our best car, I'd say it has another 10 miles in it, which would put it par with the best of the other schools. But the winning distance was awesome- a good 12% further than I expected anyway! Our best result was 7th in the 4 hr race.
Here's an in- car video of a couple of practise laps by one of the girls
[youtube]yJBGKRVeW44[/youtube]

 

[bobc]

Our next race is at Rockingham speedway this thursday coming: Live timing on the web is available from the link above.
We've made a number of improvements to "zebedee", new tyres, improved aero, altered transmission and a new control strategy, so am hoping for a better showing than the last race!
I'll post how we get on after the race!

 

[bobc]

OK not a bad day on Thursday - In the F24+ race we led throughout, but just slightly overcooked it & the batteries went flat on the last lap - that 7 minute lap cost us the win & we ended 2nd.
In the main F24 race we went staedy in the first session, but in the middle session the chain came off the car & we lost 20 minutes while the car was recovered. Then we had 2 really heavy showers that caused a lot of the electronics on both cars to fail. Things came back together in the third session & we clawed our way back to 4th place. Extrapolating 1st session data, we have (just) sufficient performance to have won the race - if we avoided other cockups. But we no longer have the luxury of a performance advantage like we've had for the last 2 years (it's another team called Rotary Racer who are in that happy position this year)
But I have a cunning plan...... ;^)

 

[pyrogaz]

So Bob, we can expect great things from CAUC and your "cunning plan" in the second half of the season? To be honest I'd be surprised if it were any other way

I notice you've stated elsewhere that the "coast and burn" technique may be beneficial, we've come to the same conclusion following Croft and Rockingham particularly when the driver weighs more than the combined weight of car and batteries! Now busily fitting a freewheel and ditching the 3/8" chain for 1/4".

Hopefully we'll be a bit closer to you at Aintree. I think we'll only be doing F24+, although our new F24 drivers could do with learning how to keep a car pointing in the right direction!

Cheers, Pyro (farnorth on GP)

 

[bobc]

Hah - I was hoping I'd be the only GP participant on here - I'll have to be careful what I say now... ;^)
I think we'll struggle getting Zebedee to the sharp end with the reduced power budget, it's just too heavy, but it should still rock in f24+ (rpods gave me quite a shock by going 7 miles further than anyone else this year at Rockingham....).
We got our average speed up by 3 or 4 mph between Silverstone & Rockingham, in very similar race/track conditions, so in retrospect I'm pretty pleased with the result there, both cars pretty much guaranteed a final place.
To be honest the "cunning plan" is a bit tricky, but might be worth a couple of percent in power terms - just have to get the soldering iron out......
Shame we didn't clock "mjolnir" at Rockingham, because we're about to venture out into vacuum bagging the monocoque for next year's car ("dougal"?)
The mickey take on the CAUC website is a mockup to check cockpit size....

 

[pyrogaz]

There's no hiding on t'interweb!

Mjolnir did well at Silverstone but didn't make much of a step forward at Croft and Rockingham, didn't help that efforts to build its control system had resulted in large quantities of magic smoke being released so had to resort to a relay; I know some teams have been very successful running "simple" but you can't do that if weight's against you.

We were very impressed with how Zeb performed but surprised at how quickly Brian started to drop off. You'll certainly have no trouble quailfying for the final with well over 80 miles, although I'm surprised that the necessary distance may well be slightly higher than last year's.

Croft was a bit disappointing for Coyote, we opted for ridiculously low gearing after spinning out of the F24+ race so that our new drivers wouldn't throw it at the scenery in F24; they still managed to do it twice and then we didn't have the speed to catch Carbon Comet despite having more than a full set of batteries remaining at the end, frustrating!

Like the new car :wink: You wouldn't be having a dig at anyone would you :lol:

 

[bobc]

That's Jeff (looks after the website) & Mr. B - all the subtlety of an express train ;^)
To be honest they are right, a car made of foam & sticks won't slow zebedee at 45mph at all if it t-boned it - & it could happen if a car spun after a blind bend (e.g. chicane at goodwood) But all we can do is make our own cars as strong/safe as possible & otherwise fit in with the rules. If it makes us uncompetitive, so be it.
I'm surprised they didn't pop some carboard tubes (say from the inside of a roll of tinfoil) into the chassis "for added strength" ;^)
We have a vid of the first corner of F24 which will be on youtube soon. Also our website should have writeups for Silverstone & Rockingham in the next couple of days - you'll see why Brian slowed so much......

 

[pyrogaz]

In last year's final my son had to take evasive action to avoid Starlight which had spun on the exit of the chicane and was sideways across the track, he was in Roadrunner which was 80kg empty so you're looking at an all up weight of 210kg travelling at probably 28mph; our group leader thought he did a remarkable job to avoid a serious incident. I've never liked the Goodwood chicane, it doesn't add anything to the race and it's probably the only blind corner in the series.

Here's a question for you, if Greenpower were extended to include an "Open" category, i.e. over 18's, no motor restriction but the same battery regs as F24+ and run alongside F24+ as a dual class race do you think many of the current team mentors and other interested folk from outside Greenpower would fancy a go?

 

[bobc]

Goodwood chicane - certainly claims more than its share of incidents, there again I'm quite sure the kids prefer a slightly more 'interesting' drive; and without things like that, the driver has practically no influence on team performance. There are other accident black spots, Darley moor hairpin, that ford track hairpin & the end of the straight at croft.... Like you say, I can't think of any other totally blind corners.
"unrestricted" class - I'm too big - don't fit in the car & weigh too much, so not much motivation for me personally.... Maybe it would take off, but what is greenpower for?- It's to enthuse kids about technology, STEM & show 'em that it's actually pretty cool to MAKE stuff; "unrestricted" class, as you suggest, doesn't really tick those boxes, it would be dominated by small thin middle aged men..........

 

[pyrogaz]

I've driven a couple of our cars round a kart track but I'm far too heavy for racing so not something I would do either, but my feeling is that the kids get a real kick out of beating teams of adults at the Corporate Challenge and to give that opportunity more often to the older students would add another dimension to F24+ without diminishing the engineering experience.

I never realised the end of the Croft straight was a blackspot, might explain why we spun there My objection to the Goodwood chicane is mainly because of its blind nature and that there's an almost permanent yellow flag there, I'd prefer to see "handling" sections on all circuits to give the drivers chance to demonstrate their ability.

Will you be using glass or carbon for Dougal? We vacuum-bagged part of Coyote's body in glass/epoxy and I was quite shocked at how heavy it was compared to an equivalent carbon/epoxy panel, however the increase in strength over traditional lay-up is remarkable. I'd have voted for Ermintrude :lol:

 

[bobc]

Another race at the Aintree track yesterday - pyrogaz was there too with 2 cars. We were running in a trial configuration with a gearbox & the trial successfully proved it slows us down! We managed to get 2nd place in both races with our best car (i.e. could do better....) beating pyro's car by just a few seconds in the first race - we had totally emptied the batteries & it was touch & go whether we'd finish ahead.
We realised we were running out of juice with about 15 minutes to go & tried to slipstream the eventual winner (which was 20s behind us at the time). This worked for 2 or 3 laps but then our power went & we slowly fell back. Both good races & an absolutely gorgeous day.
My works has entered a team of apprentices in the f24+ race series, they had a hard time with punctures & breaking things & managed (just) to come last, beaten even by the Bentley team, the traditional whipping boys of greenpower...... ;^)
Jaguar won, we were 2nd, pyro's teams (mjolnir and coyote) 3rd & 4th I think.

 

[bobc]

Last race before the finals at Castle Coombe on Sunday. We got 2nd and 3rd in the first race (beaten again by the car that beat us at Rockingham). Unfortunately this was not good enough as we needed a win to have any chance in the championship (which we have won for the last 2 years). In the other race we were well beaten with our main car going particularly poorly. We had some keystone kops moments in the pits too (e.g. putting empty batteries back in & sending the car out again.... oops). So we will have to be lucky & nail the real problem before the final in 2 weeks - without the benefit of testing facilities. Unless Zebedee gets his mojo back we're just there for a nice day out.....
+ It's never a good sign when you come away from a race with dirty hands......
Bob

 

[pyrogaz]

The Aintree race was very exciting, it's rare for the top three to finish within a couple of minutes of each other and if it hadn't been for the clever bit of slipstreaming by Zebedee the race for 2nd would have been even closer, as it is Mjolnir is performing very well when you consider the driver weighs more than some car/driver combinations on his own! Coyote had an excellent race, it was more of a test session as it was our only chance to test our F24 gearing on a long circuit before the final at Goodwood, a binding brake meant we pitted 20 minutes earlier than intended but the data obtained was very encouraging.

The F24+ championship is by no means settled, I'm expecting the top five at Goodwood to be covered by no more than a one minute,

 

[bobc]

For anybody interested; the 2011 national finals take place this Sunday at Goodwood circuit on the south coast of England. My cars are Brian and Zebedee, Pyro's are Mjolnir and Coyote. The 2 races are at 10:30 and 1:00 pm UK time and can be followed live on
http://www.bbk-online.net/gpt/event32.htm
We've won it for the last 3 years (had a good run) but probably won't this time - still, fingers crossed ;^)
I'll give a quick race review from our perspective next post. I might even see if I can get some on- board video....
Pyro has probably set off already, he's travelling from the north of Scotland with his team - Good luck guys!

 

[bobc]

OK, good races, excellent weather, but we're not champions any more - we came 3rd in the 1st race and 5th in the main race. Pretty good day for us actually, the team is starting to gel together now & we all enjoyed ourselves. Next year we'll make a new car & try to bring the trophy back home.... It's actually the first race this season when we've had a clear run and got a representative data log. From which we discovered that the "pulse and glide" control system, which in the spreadsheet simulation gave us a 5% power advantage - in reality it turns out to cost us 2mph (that's about 8% speed, so considerably more in power terms) - ouch! AH well - we know for next year.
The clear winner in the 1st race was a car called "iwhoosh" which has previously always looked great but gone like a dog. The team running this car are dealers for & sponsored by nuvinci, the CVT people. In this race however, they had finally decided to try the car direct drive, without the nuvinci gearbox... So perhaps efficiency is not the nuvinci's strongest suit - maybe a little tiny bit embarrassing... The F24+ championship was won by a team called R-pods, which was sort of nice after their main driver tragically died of cancer just a few weeks ago, his kid brother drove the car to 2nd place in this race.
The clear winner in the 2nd (main) race was a car called "Rotary Racer" - no surprise there, they have been the strongest performing school car all year & they won by a street. Even if we'd controlled our car sensibly they'd still have whupped our asses, they went 12 miles further than us (and the 4th and 3rd placed cars).
So that's it for 2011 - I'll put some notes on a new thread in 2012, just in case anyone's interested.....

 

[pyrogaz]

An excellent day's racing, we managed 8th in the first race following an electronics failure in practice (why is it a 17 year old can design, build and program a controller with power management routines, GPS lap timing, datalogging, etc, but can't reliably wire it up!) but proved the car has potential to do very well. In the second race a very creditable 7th place considering three of the five drivers had never driven the car before so we had to gear down to make sure the batteries lasted the race, as it turned out we only used 85% of the available power despite some comparatively slow and nervous laps so very much looking forward to 2012 and taking on the photovoltaic equipped teams.

Bob, we still think coasting down hill can offer improved overall efficiency but only when the overall driver/car weight goes above a certain threshold which varies depending on gradients and wind, having a 95kg driver for most races means we're usually above that threshold!

As a matter of interest one of the cars in our stable runs a NuVinci which is now 3 years old and covered around 1500 miles, when first installed it felt very difficult to turn by hand but now there's very little resistance; I suspect a very well run-in hub in a slippery car and finely controlled would do very well indeed.

 

[bobc]

Yer spot on pyro, we're going to go for a 'proportional' speed limiter which will fall back on pulse/glide at the lowest power levels.
I thought Luke's dilemma (with iwhoosh) was very funny, & to his credit he saw the funny side too - mind you it's easy to laugh when you've just slaughtered the field in a big race! It was actually Terry from Rotary Racer who told me about their transmission - he had a good laugh about it too. It's always hard with these things to interpolate what you can see/measure to what happens on track, but I reckon iwhoosh's startling turn of speed in that last race is compelling evidence that the car has been fatally held up by the nuvinci for years...
I now have a fight coming with a parent who wants to spend a fortune on ceramic bearings... that would be worth about 17 feet over a 100 mile race... fun fun fun.... But the old "spin down" test is so easy isn't it...

 

[pyrogaz]

Sounds like we're heading towards similar solutions, we're using both speed and current as parameters, and going down hill the motor may just "tickle" the car along rather than being fully on or off; we think it's better to keep the motor turning to help dissipate heat after climbing.

Luke had mentioned it to me a few weeks ago and was looking for a start point for single speed ratios, had I known how fast he was going to be I'd has suggested 5:1! Total respect to him, it's taken a long time to develop but iWhoosh is going to be very difficult to beat.

Ah, the parents who suddenly know more than someone who's been running a team for years, I think every school has at least one of those! We came to the conclusion that as long as a bearing isn't damaged the resistance they present is so low as to be negligible, ceramic are just one of those placebo components for the top cyclists and skaters.

 

[drewjet]

As a matter of interest one of the cars in our stable runs a NuVinci which is now 3 years old and covered around 1500 miles, when first installed it felt very difficult to turn by hand but now there's very little resistance; I suspect a very well run-in hub in a slippery car and finely controlled would do very well indeed.

I would like to hear more of your Nuvinci input. I am in my 3rd year of running an electrathon. We haven't lost a race yet. Before each race I carefully study the course to determine the best gear ratio. I recently purchased a Nuvinci developer kit. I have had it on the car for some testing, and it showed some dramatic improvements in acceleration times and decreased amp hour usage. However testing and actual race conditions are different. The first 2 races this season have been realtively large ovals and no need for acceleration, so I have not yet used it in a race. Next weekend our race is on a tighter course and I intend to try it out.

Do you guys have any video from your events. I know they are different than electrathons, yet similar in some respects.

Thanks

Drew

 

[bobc]

My impression is that greenpower/electrothon are very similar. You need something to cope with speed changes on anything but a flat track & the automatically controlled nuvinci looks perfect for the job, but such cars in greenpower have never really shone. We use a PWM speed controller to do the 'gearing' and it's worked well for us. We should be able to find some vids on youtube (there's a vid of a couple of practise laps at silverstone above)
http://www.youtube.com/watch?v=Kh1C4KDBQg0
last final
http://www.youtube.com/watch?v=SCtknq3jTEg&feature=related
the one before (which we won........)
Looking for "greenpower" on youtube finds lots of things, but some race footage is among it (along with lots about the "green power ranger"....)

 

[pyrogaz]

Drew, as Bob say's the NuVinci has had only limited success in Greepower, where it has done well is on tight, twisty circuits where it allows more efficient running over a wide speed range. I suspect, as you've already found, that it may be better to stick with single speed for long ovals and if possible just install the NuVinci for tighter circuits. I've not had a lot of involvement with our NuVinci car but it's manually controlled with the driver aiming to maintain a predetermined current.

Electrathon and Greenpower look broadly similar but there are a few major differences:

1. Standard batteries and motor in GP, free in ET.
2. Three wheelers allowed in ET, GP cars must have four
3. Enclosed cockpits in ET, must be open in GP.
4. GP is a four hour endurance format, ET a 1 hour sprint, although GP's F24+ is a fairly similar format.

It'd interesting for us to hear what sort of current an Electrathon car draws, the comparatively small batteries used in Greenpower mean in F24 (4 hours and 3 pairs of batteries) the average current is only 16-17A, in F24+ (90 minutes and 2 pairs of batteries) it's about 23-24A, average race speeds for the top ten are about 27mph and 33mph.

 

[drewjet]

Drew, as Bob say's the NuVinci has had only limited success in Greepower, where it has done well is on tight, twisty circuits where it allows more efficient running over a wide speed range. I suspect, as you've already found, that it may be better to stick with single speed for long ovals and if possible just install the NuVinci for tighter circuits. I've not had a lot of involvement with our NuVinci car but it's manually controlled with the driver aiming to maintain a predetermined current.

I think you are correct. When I first installed it my intent was to control manually. However in actual practice I found it difficult to concentrate on driving and watching amps and controlling the Nuvinci. After switching out to auto, it functioned much better and the degree of programming makes it always be in the right gear for the right speed

Electrathon and Greenpower look broadly similar but there are a few major differences:

1. Standard batteries and motor in GP, free in ET.
2. Three wheelers allowed in ET, GP cars must have four
3. Enclosed cockpits in ET, must be open in GP.
4. GP is a four hour endurance format, ET a 1 hour sprint, although GP's F24+ is a fairly similar format.

1 and 2 are correct, 3, the canopy can be enclosed but not required. I like the pit stop, change driver and batteries, could add some excitement.

It'd interesting for us to hear what sort of current an Electrathon car draws, the comparatively small batteries used in Greenpower mean in F24 (4 hours and 3 pairs of batteries) the average current is only 16-17A, in F24+ (90 minutes and 2 pairs of batteries) it's about 23-24A, average race speeds for the top ten are about 27mph and 33mph.

I can get about 32 Amp Hours out of my yellow top Optimas. So I do my best to get all 32 out of them in a race of 1 hour. Most of our races here in Florida are in parking lots and are very tight, some tighter than others. One race is on a running track oval, and one is on a banked oval for Nascar style racing. Out in the Western part of the Country they have most of their races on Indy style race courses.

On the tightest track we only managed to average 17 MPH, on the banked oval we managed 33 MPH. The other courses are usually around 22 to 25 MPH.

 

[drewjet]

We should be able to find some vids on youtube (there's a vid of a couple of practise laps at silverstone above)
http://www.youtube.com/watch?v=Kh1C4KDBQg0
last final
http://www.youtube.com/watch?v=SCtknq3jTEg&feature=related
the one before (which we won........)
Looking for "greenpower" on youtube finds lots of things, but some race footage is among it (along with lots about the "green power ranger"....)

Thanks for the vids

This is from our last race
http://www.youtube.com/watch?v=BSAqLUREGL4

 

[pyrogaz]

Nice video, very surprised to see races on schools roads with kerbs and lights, I doubt Greenpower's insurer's would agree to that! Interesting that the cars seem to be perfectly stable in the corners despite most being trikes. Are those Etek motors most cars are using?

Here's a good video from earlier this year at the Top Gear test track. The team who produced the video, Fireblade, were 3rd in our National final and car 27 that they're chasing won this race and the final. These laps were at an average speed of about 29mph.

http://www.youtube.com/watch?v=oYOaJfsozvM

This one is at the shortest track used in Greenpower:

http://www.youtube.com/watch?v=PhdfNVIRHUE&feature=related

The record 4 hour distance at this track is only 76miles and the tyres were virtually destroyed in the process.

Pitstops do add another dimesion to the racing, and allows team members who aren't driving the opportunity to influence the outcome of the race. The timing of pitstops is also a crucial part of race strategy, particularly at Goodwood where the lap is 2.4miles long, call you car in one lap too late and its batteries might not get it round the next lap!