FS Electric Cars vs. FS Combustion Cars

[Tropenk]

Hi,

this thread should be a place to discuss the advantages and disadvantages of the electric FS cars compare to the IC ones and vice versa.

In the topic of FS-G Hockenheim 2010 the discussion has already started, but it might be a better idea to open an extra thread for this.

To start just some insights:

Efficiency: The maximum used energy of an FSE car finishing endurance equals 0.7 liter of petrol. (The best FSC car used 2.86 liter)
How should the two concepts be compared in terms of efficiency?

Power: Some electric cars used high power motors and reduced the power of them during endurance to "save electrons". Interesting strategy or should this be forbidden by a rule?

Challenging in terms of engineering:
The claim was that the cross-discipline coordination and systems integration/engineering is much higher building electrical cars and there is usually more room to grow as a team member.

What do you think about the three statements / questions? Any other controversial issues regarding FSE / FSC?

regards
Yves

[thewoundedsoldier]

What is meant by "used high power engines and reduced the power of the motors"? I am used to the term "engine" meaning combustion engine and the term "motor" meaning electric motor. Were FSE teams allowed to run hybrid drivetrains?

Here's a new point to toss in: electric cars are dangerous!! I have never personally witnessed a four-stroke engine do something violent, but last year I got up close and personal with a 4kWh pack of shorting LiFePO4 batteries. That was fun http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Tropenk]

oh that's my fault, I meant motors, sorry for that. No hybrid was not allowed in Germany. I meant that they used two motors with like 40kW power each and reduced then the max. current to save energy.

Yes, batteries can be pretty dangerous indeed. Such a nice red/blue lithium fire can be very exciting http://fsae.com/groupee_common/emoticons/icon_smile.gif
But if one take care of the risk and realize some safety feature you should be able to deal with this problem.

IMO the FMEA (mandatory for FSE Teams) and the ESF (Electrical Safety Form) reduce the danger of the electric car to a minimum.

[thewoundedsoldier]

It sounds to me like the FSE teams strategized from the beginning to save lots of weight by going with few batteries, meaning they would be forced to lightfoot endurance. Looking at the scoring algorithms, it seems like a great strategy. They way to fix the issue would be to give more weight to the endurance event, forcing teams to use more energy storage. IMO this is better than imposing a minimum accumulator size.

[vandit]

In our briefing before the start of event, they mainly made us aware about two dangers

1. Dont touch the car if the light on top of the car is on (meaning that high voltage is on)

2. The fumes/smokes are toxic and can be fatal if inhaled in some considerable amount.

But i think the rules for safety of the car and also during event were so nicely put up that we didnt experience any danger during the event.

Thumbs up to Tobias and Lukas. Lets get some more electric cars next year.

[TMichaels]

Go on guys, I will definetely be watching this thread. Maybe this discussion will heavily influence further FSE rules releases http://fsae.com/groupee_common/emoticons/icon_smile.gif


It sounds to me like the FSE teams strategized from the beginning to save lots of weight by going with few batteries, meaning they would be forced to lightfoot endurance. Looking at the scoring algorithms, it seems like a great strategy. They way to fix the issue would be to give more weight to the endurance event, forcing teams to use more energy storage. IMO this is better than imposing a minimum accumulator size.

I don't think so and even if as long as only one team breaks with this strategy it would beat everyone in the endurance. Therefore this does not sound like a feasible strategy. The guys from Eindhoven for example were pushing the whole endurance as far as I know.

Please also remember:
If a car is not as fast as another on the track this does not have to rely on its powertrain. There is the driver, the tires, the suspension etc. We need a bigger amount of teams to really judge which of the concepts is faster.

Regards,

Tobias

[RobbyObby]

Originally posted by TMichaels:
I don't think so and even if as long as only one team breaks with this strategy it would beat everyone in the endurance. Therefore this does not sound like a feasible strategy. The guys from Eindhoven for example were pushing the whole endurance as far as I know.


According the scoring formula, however, a car that finished endurance with an medeocre time scores considerably more points than a team who finishes half the laps with the best times of the day. I have to agree with thewoundedsoldier on this one. If you can lose significant weight overall by reducing your accumulator size, with the disadvantage of a slower time in endurance, as long as you know you can finish the event, I think this is a great strategy. Just my $.02.

[RobbyObby]

Originally posted by thewoundedsoldier:
I have never personally witnessed a four-stroke engine do something violent, but last year I got up close and personal with a 4kWh pack of shorting LiFePO4 batteries. That was fun http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

That was the best fireworks show I ever witnessed!

Also, I dont think the risks at the event are the major concern. It's during the manufacturing process that teams can get lazy and overlook something, especially when working at 3 a.m.

[The AFX Master]

Originally posted by Tropenk:

Efficiency: The maximum used energy of an FSE car finishing endurance equals 0.7 liter of petrol. (The best FSC car used 2.86 liter)
How should the two concepts be compared in terms of efficiency?



Energy wich could came from a coal plant that expelled roughly 20% less emissions than the combustion F-SAE car. And got losses through transmission and conversion that could make for the gained eficciency. Same carbon footprint in both scenarios?.

Well.. being on Germany, certainly coal doesn't look like the real deal. Wind energy is developing fast there, isn't it?

Let's put a huge wind turbine onsite to charge batteries :P.

[thewoundedsoldier]

It's pretty interesting that Germany has the most robust solar energy development in the world when they get about 10% the sunshine the U.S. does.

A great way to compare efficiencies, IMO, is in consumer cost. Gasoline costs x amount. Electricity costs x amount. Convert and be converted!

[The AFX Master]

Sounding like a jerk...but:

Need some real world comparisons :S... My country is nowhere a solid basis to do that..

Half a buck for a full tank of any SUV.. Joke.

Of course electricity will be cheaper than gasoline, mainly related to the fact that gasoline still needs more energy to be produced compared with coal.. The deal on going electric is the so called going "green". I wonder if the electric cars really can lower the carbon footprint of the conventional ones.

In Solar/wind/sea/nuclear powered countries, deal. In oil floating islands like mine.. i don't think so.

[TMichaels]

The Hockenheimring recently installed a very big area of solar panels with a power delivery of up to 848,88 kW. So the FSE cars were really charged with electricity coming from regenerative sources.

But solar panels are right now not the way to got as you need several years to "get the energy back" which was used to produce them. This is also referred to as the Net Energy Gain, NEG = EnergyConsumable ? EnergyExpended

Wind mills look way better when talking about NEG.

Regarding Efficiency:
I think we do not really have to talk about in-car-efficiency. This should be, averaged, around 0,28 (FSC) compared to 0,85 (FSE).
If the electric energy comes from regenerative sources, bam, no need for discussions anymore.
If the energy comes from nuclear powerplants, its the same, since we are right now not talking about toxic waste, etc.
If we are talking about gas or coal power plants it might be close and depend on the position of the powerplant as powerplants in the US and Europe are more efficient than elsewhere.
What also should be considered is the production of toxic waste. For example 3L of oil for every combustion car per year.
Research is under way to effectively recycle Lithium-batteries (my girlfriend is doing her PhD-thesis about that), but right now, it is not done as far as I know.
Then there are the exhaust gases...
Lithium is not really a limiting factor as many people complain, because there is more Lithium available on earth than lead for example.
The development of battery-technologies is also far away from hitting the borders of the theoretical possibilities.

To sum it up: I honestly think electric is the way to go, but it may take some time to get the development level of electric cars up to the pace of combustion cars.

Regards,

Tobias

[RenM]

I don't think that the efficiency rules are really useful for the electric cars.
You can do a lot for your efficiency in the combustion car. But in the electric car there is not that much you can do about it. All components you will use, already have a very high efficiency and there is hardly anything you can do to improve that efficiency. So in the end your energy usage will be determined by your motor power and your cars weight.
So if you want to be good at efficiency you either have to be very light or very slow, but the engineering challenge is not as big as with the combustion engines.

and another question is:
why is the endurance time including penalties used for the fuel efficiency? Like this a team gets the penalty not only for one event but for two.

[thewoundedsoldier]

So if you want to be good at efficiency you either have to be very light or very slow, but the engineering challenge is not as big as with the combustion engines.

I disagree. For one, both cars can improve efficiency via weight and transmission. With respect to the powerplant, the only thing you can make more efficient in a combustion car is the engine itself. With an electric car, you can reduce the resistance of the motors, improve the motor-controller's efficiency, and consider battery choice in terms of efficiency.

I agree that any electric car is going to be *more efficient* than a combustion car, but there is still a lot of engineering one can do to improve electric efficiency.

[TMichaels]

Originally posted by RenM:
But in the electric car there is not that much you can do about it.

I also disagree. Have you ever talked to someone who is trying to get regenerative braking to work properly? It's a pain in the...you know what. That's why I am really curious to see the first 4WD FSE cars on track.

As tws said: You have to choose which motor concept to use, the voltage level, the batteries, air-cooling or water-cooling etc. It is even possible to raise your efficiency by cooling / heating your batteries to a certain temperature.
Even if these cars are more efficient by definition, this does not mean that they cannot improve on that. There are still 100 points to earn.

Regards,

Tobias

[RenM]

Originally posted by thewoundedsoldier:

I disagree. For one, both cars can improve efficiency via weight and transmission. With respect to the powerplant, the only thing you can make more efficient in a combustion car is the engine itself. With an electric car, you can reduce the resistance of the motors, improve the motor-controller's efficiency, and consider battery choice in terms of efficiency.


The difference you can gain is much much smaller for electric cars. Looking at a combustion engine you can gain 10% relative efficiency by just running lean and you can do a lot more with mixture, gas exchange, mechanical efficiency and so on. Gaining 10% relative efficiency for electric cars is near impossible if you consider that they already have about 85 or 90%.

[RenM]

Originally posted by TMichaels:
I also disagree. Have you ever talked to someone who is trying to get regenerative braking to work properly? It's a pain in the...you know what. That's why I am really curious to see the first 4WD FSE cars on track.


as far as i understood the rules, regenerative braking into the accumulators doesn't improve your efficiency at the moment, because the energy meter can not see if the energy coming from the accumulator comes from regenerative braking or not.

please correct me if i am wrong on this.

my point is: the relative gain will always be very small and thus seeing the difference in endurance is hardly possible, as other things like weight and power have a much bigger effect.

[TMichaels]

Originally posted by RenM:
as far as i understood the rules, regenerative braking into the accumulators doesn't improve your efficiency at the moment, because the energy meter can not see if the energy coming from the accumulator comes from regenerative braking or not.

please correct me if i am wrong on this.

You are right, it does not boost your efficiency scoring directly, but it helps you saving battery weight, if you are able to regenerate a certain amount of energy. And saving weight increases your efficiency as you pointed out before http://fsae.com/groupee_common/emoticons/icon_cool.gif

Regards,

Tobias

[thewoundedsoldier]

Originally posted by RenM:
The difference you can gain is much much smaller for electric cars. Looking at a combustion engine you can gain 10% relative efficiency by just running lean and you can do a lot more with mixture, gas exchange, mechanical efficiency and so on. Gaining 10% relative efficiency for electric cars is near impossible if you consider that they already have about 85 or 90%.

You're argument is that a gasoline car running with less power will consume less fuel. Well, an electric car running with less power will consume less energy just the same. I do say this from a relative standpoint.


As for efficiency, our system shows significant gains when power is reduced. I don't know about 10%, but combined with battery chemistry selection and systems design I'm sure there is a lot of room for differences between cars. As Tobias said, often you'll want to increase battery temperature so their ESR goes down. Another efficiency parameter that we have experienced is lag voltage. By requiring less power (less voltage), you can decrease your batteries' voltage drop and increase efficiency.

I'm getting off track, sorry. I think that within the broader scope of the power-to-energy-to-efficiency compromise there is a lot of room to stretch out.

[murpia]

Tobias,

Can I ask why FSG decided to mandate electric cars as an alternative to 'standard' FSAE?

It seems to me this is a bit like governments who arbitrarily subsidise certain technologies, creating a distorted market, instead of allowing the best technical / commercial solution to win out. Electric & hydrogen fuel cell cars in the real world seem to be examples of this.

This issue, of prescribing a technology, is also a possible criticism of Formula Hybrid in the USA. FSUK's Class 1A seems to be setup to allow the teams to choose for themselves what technology route to follow.

Regards, Ian

[TMichaels]

Ian,
several reasons lead to the decision to go electric only. I will try to list them all, but don't blame me, if I forget some.

At first there are organizational aspects:
To ensure a safe event, you have to be able to guarantee the safety of the vehicles. Therefore you need specialists. We had HV-specialists from the Dekra dealing all the time with full-electric cars. They did the electric-scrutineering prior to Tech&Safety. If you open up your event to a lot of different concepts, you need to find specialists for every technology to be able to do a thorough scrutineering.
The same is valid for the judges. If you have a lot of different kind of cars you also need special judges for everyone, otherwise the judging process is not fair. Just think about having an electric drive train judge and a team with a diesel engine. This will not work.
Furthermore it is hard enough to develop rules for electric cars without critical holes. If you allow other technologies as well, you open up a very big box of problems.
There was one day at FSE where I felt like doing safety briefings all day. Briefing judges, redshirts, whiteshirts, scrutis, track marshals, firefighters etc. If I had to do this for all other possible technologies as well, it would have been a nightmare and the briefed people would not have remembered a single point.
You also have to provide fuel to the teams. Not only a charging area, but also a safe place to refill diesel, ethanol, petrol, CNG, LPG, hydrogen (may be at different pressures), etc. has to be provided.

Another reason is of course the real world. The industry has a strong demand for engineers knowing how to deal with electric drivetrains. May it be to build full electric cars or hybrids. We are organizing FSE to achieve the same as with the other FS events: We want to increase the education quality of young engineers. This can of course also be done by building a hydrogen / diesel / CNG powered car, but we had to choose and we chose electric.

Then there is the complexity. I saw a lot of teams struggle with the complexity of hybrid cars for example. A very interesting psychological study once revealed that having too much choices is as bad as having to few. We want to have as many driving cars as possible and as few frustrated students as possible. Restricting the choices is a good thing as long as there are still some decisions to make and this is definitely the case for FSE. The application is often underestimated. Getting a smooth mapping for only one electric motor or one combustion engine is difficult enough. Doing this for two different kinds of motors / engines is next to impossible within one year with respect to the available resources.

The last thing is the performance: Looking at the results of the autocross from FS UK Class 1A 2010 the electric cars wiped the floor with the other concepts. Of course there were not taking enough teams part at the autocross and at the whole event to say that this result has any statistical significance, but the last two years full electric cars took part and the last two years a full electric car won the competition and in my opinion this will continue, if the rules do not change heavily.
If this changes in the future, we will think about opening up the FSE rules to other concepts as well. But right now, we will lean back and see, how it develops http://fsae.com/groupee_common/emoticons/icon_smile.gif

Regards,

Tobias

[TMichaels]

A little addition, but not an official FSE organisation statement, only my personal opinion:
In swimming there is freestyle and swimming the crawl as two different disciplines. But in freestyle everybody is swimming the crawl even though other styles are allowed. We skip frestyle and only allow swimming the crawl instead http://fsae.com/groupee_common/emoticons/icon_cool.gif

Regards,

Tobias

[blister]

I was involved in 3 ICE Cars and last year in our first full electric car. It was a lot more fun to work on our first electric car than on our first petrol car. Less problems, better perfomance, more improvements over the season and so on.

Imagine what happens if Stuttgart continues with only an FSE team; if Delft switches to a 160kg electric car; if Zwickau brings the 4WD to life, if Eindhoven improves their weight, or if Zurich usese AC Motors and starts to prepare the statics (...)

This was the first year for the FSE Class in Germany and Austria and you know what: in Austria ALL four electric teams completed endurance. The ICE Cars had a finish rate of less than 50%. In Austria Eindhoven and Zürich were 4th and 5th overall. Eindhoven needs a lighter car and Zurich better statics and they would have been on the podium against petrol cars.

So for me as a chassis suspenion/chassis guy the best thing is probably that we were already on the traction and cornering limit of the car all the time. So the tires were already the limiting factor all the time.

I just hope that some well placed teams will switch to electric cars and that we will hopefully not see 100s of 4cylinders weighing 220kg in Europe...

[Bemo]

To my experience it takes a lot more to get an electric car running at all compared to a combustion car. For an IC car you can buy an engine and somehow you will get it running. If nothing else helps you can use a carburetor.

I think the reason for the success of FSE in this first year is that several experienced teams took part and that it was possible to use old chassis. In our case it would have been impossible to design a new frame and a new suspension and get the powertrain done in time.

I guess in the future there won't be this "old chassis" rule anymore, so FSE teams will have to design the cars from scratch like in FSC. It will be interesting to see how the whole thing will develop from that point. It won't be a big thing for teams which switched completely to FSE, but it will be a problem, if one uni participates in both events.

[thewoundedsoldier]

It won't be a big thing for teams which switched completely to FSE, but it will be a problem, if one uni participates in both events.

The two-team unis are at the best advantage! They can design the chassis in parallel and split work tasks! This is assuming double the team members, but you should only have two teams if you are capable of having two teams (haha insert joke at SJSU's three 2010 racing teams and zero endurance finishes here).

[Bemo]

Originally posted by thewoundedsoldier:

The two-team unis are at the best advantage! They can design the chassis in parallel and split work tasks! This is assuming double the team members, but you should only have two teams if you are capable of having two teams (haha insert joke at SJSU's three 2010 racing teams and zero endurance finishes here).

The problem is, that you won't have double the team members. In fact we have trouble to find enough motivated new members for one team.

Also designing a chassis which has to fit for combustion and electric powertrains will always be a compromise.

In the end it will be a clear disadvantage if one uni builds two cars, because you have to split the manpower you have and also all your other resources won't just double up, because you have two teams. I'm absolutely convinced that on the long term at most unis there will be a decision for combustion or electric, not many will do both.

[thewoundedsoldier]

Tuche--sponsorship is infinitely easier for the "green" teams.

[Hub]

But cost are probably much higher.

[MH]

Ok guys, let’s not carried away here. I agree that electric cars have great potential, but we’re not there yet.

For now electric FS cars are no match for combustion cars, only on accel. If you compare laptimes on endurance there is still a considerable gap. Of course this has everything to do with weight. When the e-teams get their weight down, that’s when it will become interesting.

But let’s not forget that the combustion cars have an effective limitation on their power, while electric cars don’t. I would imagine that being the next step in the regulations, there’s a good reason for the restrictor on combustion cars.

Of course the tyres are the limiting factor on an FS racetrack!! I’d say about 95% of the time! We don’t have very long straights to really profit from the power, remember? Braking, corner entry, mid-corner, corner-exit are all traction limited. By the time you get to power limited you’re almost at the end of the straight.

There is another discussion which is a bit strange to me and that’s fuel efficiency comparison between combustion and electric cars. The most important issue at this time is CO2 emission, therefore it is logical to use that as the means of comparison.
If you take the ‘cradle-to-grave’ method of several governments (and the World Energy Council) you’ll have to take into account the carbon footprint of the electricity. For example wind power is in the order of 5 g CO2 / kWh. (ref. www.parliament.uk/documents/post/postpn268.pdf (http://www.parliament.uk/documents/post/postpn268.pdf)) Of course it’s very easy to assume that the electricity came from wind power, but the fact is that in 2009 about 2% of the world’s power came from windpower (ref. http://en.wikipedia.org/wiki/Wind_power), while coal accounted for 44% (ref. http://www.eia.doe.gov/oiaf/ie...f/0484%282010%29.pdf (http://www.eia.doe.gov/oiaf/ieo/pdf/0484%282010%29.pdf))

I think it would be more fair to calculate a sort of “weighted average CO2 emission / kWh” and use that to compare it to combustion car emissions. Similarly people could argue that cars running on E-85 (made from Brazilian sugar cane) have only emissions due to that 15% petrol. The bio part is called CO2 neutral, because the plants absorb CO2 in their lifetime.

So I guess there is a lot of thinking to do before we can compare electric with combustion...

regards,
Miki Hegedus
Delft University of Technology 2001-2008

[TMichaels]

Regarding the power:
Only one team had significantly more peak power than the combustion cars, this was Stuttgart with about 94kW. The next one was Zwickau with 74kW and all others were below 70kW. As you mentioned, power has only very little influence on autocross or endurance lap times.

Regarding the efficiency: I agree that it would be a feasible solution to break it down to CO2 emission. Calculating an average should do the job, but where to start and where to stop? Especially for petrol? Because petrol has to be transported etc. Also coal for example has to be transported to the power plants. And what about nuclear power plants? They do not produce any CO2 after being built....therefore they should have a level of CO2 emission equal to wind power, but they produce toxic waste.
The same problem occurs with Ethanol. You have to grow it and you need to use machines to do this and you have to transport it. Again the same question: Where to start and where to stop calculating CO2 emissions?

This is the first part were we need to make a decision: Where to start and where to stop calculating the CO2 footprint? Any suggestions?

Regards,

Tobias

[MH]

Tobi!!

That's why I included the 1st reference in my previous post http://fsae.com/groupee_common/emoticons/icon_wink.gif

The equivalent carbon footprint comprises extraction, transport, processing, construction, operation, maintenance and decommissioning. This is the so called "cradle-to-grave" method.

You can use this method for all forms of electrical power generation AND for all fuel types to get an equivalent CO2 emission.

The best part: it's being done already by scientists http://fsae.com/groupee_common/emoticons/icon_biggrin.gif In fact there are many tables to be found on the Internet with current values and future expectations.

regards,
Miki Hegedus
Delft University of Technology 2001-2008

[TMichaels]

Miki,
I read that, but it does not include petrol, ethanol etc http://fsae.com/groupee_common/emoticons/icon_wink.gif
Furthermore plants being grown for ethanol production produce a lot of other greenhouse gases. This is getting really difficult...

BTW: I read the theory of building a large solar power plant next to a solarpanel factory and then use the energy from the solar power plant to build new solar panels. This would reduce the carbon footprint of solar panels very much.

Regards,

Tobi

[MH]

Agreed, there are also attempts to calculate some kind of CO2 compensation for all the land that is being turned into bio-fuel producing land. Meaning forrests are being chopped http://fsae.com/groupee_common/emoticons/icon_frown.gif

The point is, there is already a lot of research going on, it is up to us to select a method which is meaningful.

No not easy at all. But if it wasn't difficult, it wouldn't be fun, now would it?

regards,
Miki Hegedus
Delft University of Technology

[TMichaels]

What we could use is one of the several "well to tank" reports. Preferably a report which was not driven by car manufacturers, oil companies or extremely green people. Because we are measuring during the event the consumption of fuel / electrical energy and could then just use the factor between petrol and electricity from a "well to tank" report.

It is a pity that it takes days for a post with a link to show up. Just google "CEC-600-2007-002-D.PDF".

Regards,

Tobias

[murpia]

The FSUK Class 1A rules already contains a set of comparisons for CO2 emissions from various energy sources, as far as I know the electricity number is for a realistic electric generation mix rather than 'idealistic'. The sustainability rules account for cradle-to-grave embedded CO2.

h t t p : // w w w.formulastudent.com/Libraries/Documents/Class_1A_rules_2010_1.sflb.ashx

It would be interesting to get opinions on how good those rules are.

Regards, Ian

[Bemo]

Originally posted by MH:
Ok guys, let’s not carried away here. I agree that electric cars have great potential, but we’re not there yet.

For now electric FS cars are no match for combustion cars, only on accel. If you compare laptimes on endurance there is still a considerable gap. Of course this has everything to do with weight. When the e-teams get their weight down, that’s when it will become interesting.


We would have been fifth in autocross of the combustion teams. And the very first time our car was driving under full power was Wednesday morning before scrutineering!
Also endurance times don't tell too much, as our drivers "carried the car home" after Zwickau and Zürich were out. Our best lap times weren't far from the top times of combustion teams.

If you take into account that this was the first year of FSE, than you have to admit that the level was already very high and I'm absolutely convinced that next year the best times in autocross will be set by electric cars, no matter if power will be limited or not.

I'd say the results of FS Austria support my oppinion.

[MH]

Hi Bemo,

Like I said, electric cars do have great potential, so we agree on that. The level of 1st year cars is also quite amazing.

But let's not forget a couple of things. If I heard correctly the Greenteam Stuttgart car used the same chassis design as the previous one, of which everybody knows was a very good car to handle. As far as I know it was also built by some quite experienced people (correct me if I'm wrong). Furthermore you put a driver behind the wheel with 17? 18? events experience and if I'm not mistaking some motorsport experience as well. And knowing him, he wasn't carrying the car home http://fsae.com/groupee_common/emoticons/icon_wink.gif

So while I really think that Stuttgart Greenteam did an amazing job, I still don't think the e-cars are there yet. They will only be competitive if they get the car handling right and a lot of that is weight.

Furthermore I'm quite puzzled by your statement that next year the times will be set by e-cars. Why is that? I think we can agree that on a track like Hockenheim, car handling is vital. Is the handling of e-cars better than combustion teams? I would say no, until the weight is comparable.

But I heard some rumours that some of the better teams are switching to electric, so who knows? You just might be right http://fsae.com/groupee_common/emoticons/icon_wink.gif

regards,
Miki Hegedus
Delft University of Technology 2001-2008

[TMichaels]

I would second Bemo's opinion as well as Miki's:
The cars need some time especially regarding sophisticated strategies to control two or more separate motors and for reducing weight. As far as I know only two cars, Zurich and Eindhoven, have seen mentionable testing time. This will of course improve with the experience of the teams and that will also lead to a better performance of all E-Cars. Getting the setup right usually comes after sorting out reliability issues and initial system testing. I would like to hear the opinion of the drivers regarding the status of the FSE cars with respect to driveability, because I am not really sure if weight is the main problem here.
As mentioned above it could be more related to less testing and maybe some wrong design assumptions.

However, time will tell.

Regards,

Tobias

[Bemo]

Hey Miki,

Several points are true. First thing is that our car was based on the chassis of our '08 combustion car. That was in general because of a lack of manpower. We were only 15 people, so it would have been impossible to design the whole chassis from scratch and still get the drivetrain done.
It is also true that most of us had quite a lot of Formula Student experience (just look at my signature ;-)). But none of the experienced members had ever anything to do with electric drivetrains!
And last but not least. I'll admit that with Micheal we propably had one of the most experienced drivers in Formula Student. But the first time he was sitting in the car was Friday night! And if you're honest the top combustion teams ususally don't have beginners at the wheel, so if we want to compare lap times, it is only fair if we also have someone with experience ;-).
But for Flo who was our second driver it was the first endurance and he definitely wasn't pushing it to the limit.

Now I'll try to explain why I'm so sure that times will be set be e-cars next year. Major problem at the moment ist weight. Our car was 280kg. But what we saw this year is that we had much more power than needed (in Autocross we had limited it to 70%), so if I would build the next year I would definitely choose lighter and smaller engines with less power. I'm pretty sure that we could reduce our weight to 250kg, which is of course still heavier than the top combustion teams. But don't underestimate the possibilities given by driving with multiple engines. Our torque vectoring system wasn't tested at all in Hockenheim, so even this car still got a lot of potential.
And I can absolutely garantee you that as soon as a team manages to have engines at all four wheels and to get enough testing time to develop their vehicle dynamics controls, combustion cars won't even have a small chance to compete with these cars on track.

[blister]

Technically our main problem were the motors and in general a very poor made HV system. I hope the new team can sort out this negative points.

But honestly the problem was testing time. Last year we had around 300km befor UK and 700km before Germany. This year we had maybe 100km before UK and 150km before Germany. To some extent it was also down to the motors. The main reasons however were:
- Very few people motivated for daily testing
- Worse and less test tracks compared to last year
- Driver availability

So it all comes down to project management and organisational aspects.

I agree with the weight of cars beeing too high. But I remember Stuttgart smoking the competition in 2007 with a 225 kg car...Lots ot testing time, good drivers, motivated team

I bet next year we will see a 200kg car with 75kW, enough energy and superior vehicle controls.

[TMichaels]

We also managed to win design and autocross and come in as second overall in 2008 with our 230kg behemoth. Fast cars do not necessarily have a low weight http://fsae.com/groupee_common/emoticons/icon_wink.gif
But please don't turn this thread into a weight discussion http://fsae.com/groupee_common/emoticons/icon_smile.gif

Regards,

Tobias

[MH]

I can counter that: this year Delft didn't make it to Design Finals but cleaned house on AutoX, Endurance and Fuel Efficiency (and overall) http://fsae.com/groupee_common/emoticons/icon_wink.gif

What is with ze Germans not telling the whole story? http://fsae.com/groupee_common/emoticons/icon_biggrin.gif
In 2008 you guys had a hell of team, performing excellently on statics (winning design, very high on cost etc.) The autocross had something to do with tyre-choice I believe? Yes you won that, but during enduro you suffered a lot...

On topic: I like the idea of 4 wheel drive electric cars and torque vectoring. It will mean some develoment but it's very promising!! Of course you're right weight isn't everything (it sure makes things easier though), the whole package counts these days. Preparation for Statics, organization of the team, drivers, mechanics (want to remind Munich of the 2 min penalty?) and so on...

I am a bit worried about the safety of electronic control systems, which are difficult to scrutinize. There is a good reason that drive-by-wire is prohibited in combustion FS cars. So the rules for e-cars have to keep evolving, just like the e-cars themselves...

Enough rambling for now...

best regards,
Miki Hegedus
Delft University of Technology 2001-2008

[TMichaels]

Originally posted by MH:
I can counter that: this year Delft didn't make it to Design Finals but cleaned house on AutoX, Endurance and Fuel Efficiency (and overall) http://fsae.com/groupee_common/emoticons/icon_wink.gif
Don't get me started Miki, the car was a copy from last year http://fsae.com/groupee_common/emoticons/icon_biggrin.gif Furthermore this may tell that the car was fast, but nobody really knew why http://fsae.com/groupee_common/emoticons/icon_smile.gif Enough bashing from my side.


In 2008 you guys had a hell of team, performing excellently on statics (winning design, very high on cost etc.) The autocross had something to do with tyre-choice I believe? Yes you won that, but during enduro you suffered a lot...
In fact the tyre choice was why we won autocross and why we suffered in endurance http://fsae.com/groupee_common/emoticons/icon_smile.gif But suffering is a bit harsh as we only lost 15 points to Delft. Additionally our first driver, the autocross winner, was ill on endurance day with headache and fever, but still managed to do some clean and fast laps in the endurance, but was completely exhausted and told he should have not been driving. Enough complaining, we are discussing about electric cars here! We have to stop going off-topic.


I am a bit worried about the safety of electronic control systems, which are difficult to scrutinize. There is a good reason that drive-by-wire is prohibited in combustion FS cars. So the rules for e-cars have to keep evolving, just like the e-cars themselves...


The reason in FSC for the prohibited throttle-by-wire systems is that then mechanical engineers will try to design these systems which will end up in a catastrophe http://fsae.com/groupee_common/emoticons/icon_cool.gif
Be sure that we keep an eye on it. The rules will greatly improve regarding safety this year, because of the experience we gained. The FSE cars will probably be even safer than combustion cars in 2011.

I always remember something a specialist for technical reliability once told me:
"Do you know the difference between hardware and software with respect to reliability?" - "Software is defective from the beginning..."

Regards,

Tobias

[blister]

Tobias,

When can we expect the new rules? Some major changes also concerning choice of hardware?

[TMichaels]

We are currently working on a document containing major changes and we plan to publish it as soon as possible, hopefully at the end of this week. There will not be big changes with respect to HV hardware affecting a team's concept except of a possible power limitation. In fact this is the last point which we are currently discussing.
Chassis will have to comply to the 2011 rules, but an old design may be rebuild, if it complies and has not been used in FSE before.

Regards,

Tobias

[MH]

I think that the whole discussion "setting goals at the beginning of the year" is something which applies to electric cars as well...
As long as the performance on track will gain much higher points than just the Design Event, there will always be teams that focus on the dynamics. Why? Because that's obviously the way to win competitions!! Therefore you will always have teams that have only very minor changes in their design and gain a lot of testing/driver training time. Delft chose this approach this year. Who are we to judge that approach??

The same will be true for electric cars. Once you have conceived a concept (let's say torque vectoring, 4 wheel drive etc.) that works for your team, you will not re-invent the wheel every year if you want to be an overall winner. Then you will focus on improving the existing software, focus more time on getting the right parameters etc. You might not even change anything on the software or the car for that matter!!

Furthermore somehow I don't think building e-cars will be prohibited for mechanical engineers. I'm sure there will be a lot of them who will give it a try, even if it's not "their" territory. That's why I hope the rules will be strict and clear and more importantly that they can be checked properly by the scrutineers. But that's your job http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

regards,
MH

[TMichaels]

Miki, I just wanted to tease you, calm down http://fsae.com/groupee_common/emoticons/icon_smile.gif


Furthermore somehow I don't think building e-cars will be prohibited for mechanical engineers. I'm sure there will be a lot of them who will give it a try, even if it's not "their" territory. That's why I hope the rules will be strict and clear and more importantly that they can be checked properly by the scrutineers. But that's your job Big Grin

We are always trying to find a good compromise between design freedom and necessary safety rules. We will also introduce some clarifications this year to make it easier to check the throttle-by-wire systems during scrutineering.

Regards,

Tobias

[TMichaels]

We just published the planned major rules changes for the FSE 2011 rules.
w w w .formulastudentelectric.de/uploads/media/Planned_Rules_Changes_FSE_2011.pdf

Regards,

Tobias

[blister]

Thx Tobias,

I see a internal team fight about which ready to drive sound we shall use ;-)

How about a roar of a GSXR at 14000RPM?

[Thrainer]

Most things are as expected and a lot seems to be just clarification.

Wow, 100 kW is like a 50 mm restrictor and 1000 ccm. I don't see any difference between "no power limitation" and "100 kW limit", but don't mind the rule at all. How much peak power did Greenteam Stuttgart draw this year?

I fear this could be nasty:
"6.14 Energy Storage
An accessible element/fuse/connector will be specified which should be able to disconnect the HV-system from the car in case of (a) stuck accumulator insulation relay(s) for example."

An accessible element through which all the HV power flows? Sounds like a realibility and a safety problem to me. The AIRs are the safety elements and should not fail. Even if they fail, it's like having fuel inside the fuel tank and fuel rail, but not a real threat. You would coincidentially need a ground fault etc. etc. Failure of the brake system for example is a much greater threat in my opinion, and nobody has a backup for that (yes, two brake circuits, but we also have two AIRs).
Maybe you can give more details to explain your reasons.

We could move the TSAL to under the top of the roll hoop. Why specify the colour? It should simply be visible, in my opinion.

I would like a clarification for the materials of accumulator containments. If we put the batteries into the monocoque, does the entire monocoque have to be made of non-burning composites? Or just a "firewall" between the cells and the structure.

About the protection of HV wires, I propose that approved metal shielded wires do not have to run in conduit.

Regards,
Thomas

[TMichaels]

Originally posted by blister:
Thx Tobias,

I see a internal team fight about which ready to drive sound we shall use ;-)

How about a roar of a GSXR at 14000RPM?
That is why the document said: It may be further specified....

Regards,

Tobias

[TMichaels]

Originally posted by Thrainer:
Most things are as expected and a lot seems to be just clarification.

Wow, 100 kW is like a 50 mm restrictor and 1000 ccm. I don't see any difference between "no power limitation" and "100 kW limit", but don't mind the rule at all. How much peak power did Greenteam Stuttgart draw this year?
This is the limitation at the battery, not the motors. Calculating with losses through the wiring, controller, motor, gearing etc. you should end up with something about 78kW with average efficiencies. Of course you can boost it, if you manage to get higher efficiencies in your system. Therefore it is a restriction in our opinion.


I fear this could be nasty:
"6.14 Energy Storage
An accessible element/fuse/connector will be specified which should be able to disconnect the HV-system from the car in case of (a) stuck accumulator insulation relay(s) for example."

An accessible element through which all the HV power flows? Sounds like a realibility and a safety problem to me. The AIRs are the safety elements and should not fail. Even if they fail, it's like having fuel inside the fuel tank and fuel rail, but not a real threat. You would coincidentially need a ground fault etc. etc. Failure of the brake system for example is a much greater threat in my opinion, and nobody has a backup for that (yes, two brake circuits, but we also have two AIRs).
Maybe you can give more details to explain your reasons.

We had three teams on the event which mangaged to damage both AIRs in a way that they got stuck in the closed position. Therefore they had to disassemble their wiring under high-voltage. It happened once on the dynamics area.
Several other teams told us that they had, at least once, stuck AIRs. Of course, this should not happen, if the AIRs are handled properly, but the teams are still gaining experience.
I agree that you need another falure to make it a risk, but the IMD or the BMS will not be able to shut down the system in case of such a failure, if the AIRs are stuck. Pulling the handle is bullet-proof to move the car to a safe condition.
There was also one team, TU Graz, which had such an element installed and it was very well integrated and seemed not to be a reliability or safety issue.
I also do not see a real problem in this. A kind of loopback connector or removable fuse for example should do the job.


We could move the TSAL to under the top of the roll hoop. Why specify the colour? It should simply be visible, in my opinion.

Under the top of the roll hoop is also the position where we plan to put it.
Regarding the color: We got a lot of feedback regarding the visibility by the marshalls. We had to pull several teams out on Saturday and they had to change their TSALs. It is way easier to just standardize it than to check every single solution. You have to try to change to the organizer's point of view. Standardization makes things like scrutineering a lot easier and in this case it does not affect the performance or the design freedom of the teams.


I would like a clarification for the materials of accumulator containments. If we put the batteries into the monocoque, does the entire monocoque have to be made of non-burning composites? Or just a "firewall" between the cells and the structure.
I am not qualified to answer this directly, but we will discuss this and maybe clarify it in the rules. If you need a fast answer, shoot a mail to fse-rules@formulastudent.de


About the protection of HV wires, I propose that approved metal shielded wires do not have to run in conduit.

There will be a lot of small changes and clarifications, including the wiring and conduit, which we have not mentioned in the document.

Regards,

Tobias

[Bemo]

Originally posted by Thrainer:
Wow, 100 kW is like a 50 mm restrictor and 1000 ccm. I don't see any difference between "no power limitation" and "100 kW limit", but don't mind the rule at all. How much peak power did Greenteam Stuttgart draw this year?



Our peak power was 94kW. But as Tobi already mentioned, to get that power out of the motors the power coming from the accumulators has to be above 100kW. That means that we've build the most powerful FS car which got a scrutineering sticker for all times http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Most of the changes make sense in my opinion although it would be a shame if we wouldn't be allowed to drive with our green light anymore.

According the AIRs I definitely agree with Tobi. We ourselves had trouble with them getting stuck due to a lack of experience. I guess none of the experienced teams will have a lot of trouble with them in the future. But as hopefully there will be new FSE teams next year, very likely similar incidents will happen again.

I'm also curios about the clarifications about the ready to drive sound. It would be fun if this would be up to the teams...

[TMichaels]

Originally posted by Bemo:
Most of the changes make sense in my opinion although it would be a shame if we wouldn't be allowed to drive with our green light anymore.

We will see http://fsae.com/groupee_common/emoticons/icon_cool.gif


I'm also curios about the clarifications about the ready to drive sound. It would be fun if this would be up to the teams...
The problem is: If we leave it to the teams, some of them will abuse the given freedom and we will hear animals, burps, music, movie citations etc. But we need this sound to sensibilize the marshals around the car that it is ready to drive now. That is why we plan to standardize it to a certain point.

Regards,

Tobias

[Bemo]

The reason for standardization is pretty clear. But it would still be funny...

[MH]

I see a new award: Best use of "ready-to-drive-sound" http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

regards,
Miki Hegedus
Delft University of Technology 2001-2008

[blister]

Tobi,

What are your thoughts about HV and wheel hub motor?

Think about a wheel getting loose and the HV cables remaining the only MECHANICAL connection between the wheel and the car

thx

[TMichaels]

Originally posted by blister:
Tobi,

What are your thoughts about HV and wheel hub motor?

Think about a wheel getting loose and the HV cables remaining the only MECHANICAL connection between the wheel and the car


If a whole wheel assembly breaks off the car, there should be the brake line and the HV cables left holding the assembly. The brake line is pretty sturdy and should be able to carry the load of the assembly, I think. However, maybe the best is to analyze the situation step by step.

The car is on the track, no matter where. The wheel assembly breaks off. To my understanding this is likely to happen in a braking zone. Therefore if it does not completely fall off, it will be dragged by the braking line and cables next to the car. The driver will continue braking, even if the car starts to spin. If the wheel assembly was ripped off the car, you have two open HV cables which may be live. Maybe because, if the driver is already braking, the controller should not try to source any power to the wheel. If they touch each other a fuse should react. If one of these open wires touches the frame / chassis, the IMD will react and shut down the system. If the driver has not done it before, which is likely in my opinion. The track marshals will arrive after the car has stopped. At FSG2010 every marshal was equipped with HV safety gloves, so it should be no problem.
In generall I see no problem with such a failure. What is your opinion about it?

The motor controller / inverter should be able to detect whether a motor is connected or not (at least by checking the resolver for plausibility, if an AC-motor is used) and shut down the power automatically. The Kelly's don't do it as far as I know, but it would be a nice feature.

Regards,

Tobias

[Thrainer]

Originally posted by TMichaels:
... Several other teams told us that they had, at least once, stuck AIRs. Of course, this should not happen, if the AIRs are handled properly, but the teams are still gaining experience. ...

You know better than me that these problems are because of a lack of precharging of the capacities in the controller. You have already announced a rule about this.
So, teams are not able to use AIRs correctly. Then my assumption is that at least one team will build an "emergency plug" which can be dangerous. "Easy to reach" and "HV system" don't go together well in my opinion.

Please tell us more about TUG's solution, maybe I'll loose my worries.


Concerning hub motors, I understand they are forbidden in Class 1A at Formula Student (except LV hub motors?):

"B8.14.2 Any fuel, compressed gasses, other energy storage media, HV systems and HV wiring must be contained within the primary structure of the frame and when located less than 350mm from the ground must be protected from side or rear impacts with a structure built to Rule B3.24 or B3.31 as applicable."

Does anybody know what defines a rear impact structure in FSAE? In a drivetrain layout like WHZ Electric had this year, the motors tend to be at the rear end of the car.

Regards,
Thomas

[blister]

I think it must be clear to the chassis engineers what is a HV containment and until where it has to be in the "main structure". Is it till the main relais? Energy Meter box? I can go even further: Where is the main structure behind the Main roll hoop bracing?

Maybe something like: "until the main relais inside of the main structure; until the controllers (incl. Energy meter box) inside the roll planes (like airboxes for ICE Cars); free placement of the HV cables/system between controllers and motors"

I am not againt hub motors from a conceptual point of view, but i think it is not as safe as the rest of the HV Rules.

greets, urs

[TMichaels]

Originally posted by blister:
I think it must be clear to the chassis engineers what is a HV containment and until where it has to be in the "main structure". Is it till the main relais? Energy Meter box? I can go even further: Where is the main structure behind the Main roll hoop bracing?

Maybe something like: "until the main relais inside of the main structure; until the controllers (incl. Energy meter box) inside the roll planes (like airboxes for ICE Cars); free placement of the HV cables/system between controllers and motors"

I am not againt hub motors from a conceptual point of view, but i think it is not as safe as the rest of the HV Rules.

greets, urs

You are right, thanks for the feedback! We will clarify this in the FSE 2011 rules.

In my opinion, without having been talking to the other guys in the rules committee of FSE, hub motors are not a real safety issue as the HV lines supplying them should not be live during or after a crash, because the motor controller should cut the power. Usually the HV system is also shutdown by the driver or the IMD, if it was a heavy crash, depends on the situation.

Regards,

Tobias