2013 FSUK

[BeunMan]

Formula Student UK 2013 starts tomorrow at 14h GMT+1.

Time for a 'Wings do/don't work?' discussion?

[JulianH]

Our car just left for Silverstone. We are looking forward to meet all the teams for the first time at competition.

I think a "Wings (don't) work" discussion is not needed anymore. Everybody knows that they help your car going a bit faster and that's it.

[Bemo]

Thank god, going fast is the only thing you get points for in FSAE http://fsae.com/groupee_common/emoticons/icon_wink.gif

From what I saw at ZF race camp at Friedrichshafen two weeks ago most of the top teams are using wings this year. But the size of the wings differs quite a lot from team to team.

[BeunMan]

Anyway. For your convenience I created a tool last year to find facebook/twitter posts about FSAE event and updated it to meet current Facebook/twitter programming standards

You need to login with twitter/facebook on the left for it to work: Klick here (http://80.112.145.70/fs/fs.html)

Looking forward to some real action of Petrol vs Electrics this weekend. And maybe some exploding tires at copse http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Jakob]

Does anybody know if there will be an video stream of the dynamic events like in Germany?

[TMichaels]

I just uploaded some photos taken yesterday:
https://plus.google.com/photos...thkey=CKjc-oilt8XuHQ (https://plus.google.com/photos/105516328773229091928/albums/5897027221747424625?authkey=CKjc-oilt8XuHQ)

I was busy in Scrutinering, so I did not take many pictures.

[TMichaels]

Pictures taken on Friday:
https://plus.google.com/photos...hkey=CPvOgOOGo6uQigE (https://plus.google.com/photos/105516328773229091928/albums/5897397752696033713?authkey=CPvOgOOGo6uQigE)

11 EV teams passed EV tech inspection and 8 of these also passed rain so far.

[bakirci]

Does anyone know if there is live radio from the dynamic events? Radio Silverstone is not broadcasting.

[BeunMan]

As far as I have found there is no radio stream online ...

[Pennyman]

Thanks for the photos Tobias, keep 'em coming. Always appreciate the updates.

[TMichaels]

I have just taken pictures of all available results. You can find them here:
https://plus.google.com/photos...hkey=CMHsgtPKmcq-tAE (https://plus.google.com/photos/105516328773229091928/albums/5897571364358191505?authkey=CMHsgtPKmcq-tAE)

[Pennyman]

Seeing a lot of familiar names at the top. Those top acceleration times are wildly quick. For the other sub-4 second runs, I'm assuming Delft and Dresden times were run by electric vehicles?

Also, that top Stuttgart skidpad time is 0.383s faster than their time in MIS, quite an improvement.

Thanks again Tobias http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Markus]

Well that's a different car on a different track, so apples and oranges I guess?

So far looks interesting, we'll see how it goes. E-teams seem to have an upper hand before endurance but endu will level things out some... http://fsae.com/groupee_common/emoticons/icon_smile.gif

[BeunMan]

Top accel was:

1 University of Stuttgart -- Electric
2 Delft University of Technology -- Electric
3 TU Dresden -- Electric
4 University of Padova -- Petrol
5 UAS Zwickau -- Electric
6 Karlsruhe Institute of Technology (KIT) -- Petrol

Kit-e was faster but DQ'd for using over 85 KW of power.

[Markus]

Wow, new record for DNF's? http://fsae.com/groupee_common/emoticons/icon_eek.gif

[Luniz]

Ho many cars did actually finish endurance? something around 18?

[Thrainer]

Yesterday, I was very impressed that all four electric 4WD cars with wings lived up to the expectations and secured the top4 placings in the Sprint. Today showed again that FS competition is very early for most teams and cars are not reliable yet.


Originally posted by Markus:... E-teams seem to have an upper hand before endurance but endu will level things out some... http://fsae.com/groupee_common/emoticons/icon_smile.gif
Well, there can always be surprises. If the tweeted times are correct, ETH Zurich (electric 4WD aero) was in average more than one second per lap faster than Uni Stuttgart (combustion 2WD aero), which was also slower than UAS Zwickau (electric 2WD no aero).

One reason why ETH runs faster endurance this year is that current efficiency rules reward fast cars, another is that most of the braking energy can be recuperated to the battery. I am looking forward to FS Austria for another epic battle.

The question now is: Will Formula Student change the rules to influence the balance between concepts?

Regards,
Thomas
AMZ ETH Zurich 2008-2011

[Markus]

Well, there can always be surprises. If the tweeted times are correct, ETH Zurich (electric 4WD aero) was in average more than one second per lap faster than Uni Stuttgart (combustion 2WD aero), which was also slower than UAS Zwickau (electric 2WD no aero).

One reason why ETH runs faster endurance this year is that current efficiency rules reward fast cars, another is that most of the braking energy can be recuperated to the battery. I am looking forward to FS Austria for another epic battle.
Well in autocross the difference between Zurich and Stuttgart C was about 3 seconds, so they had a benefit of 2 seconds per lap in endurance. That's still quite a lot, but if it isn't enough then it isn't.

Do you have laptimes for any of the faster (in autox) C-cars for comparison?

[Dunk Mckay]

I'm not 100% sure why efficiency rules should reward fast cars, the endurance event is worth 300 points and rewards fast cars, why do it twice? Despite being one of only a few teams to survive the grueling challenge yesterday we were only awarded a small 62 points of the 300, 50 for finishing and 12 out of 250 for our time.

We were held up by all the cars out there when we were running (yes that's our own fault for having issues in autox). But something more should be done to prevent that being a big an issue. Penalties for not pulling in under a blue flag, and potentially penalties for stopping on track for more than a certain duration (as opposed to pulling out of the way when you realize you are in trouble). The latter is a little harder to implement perhaps.

But also due to the lack of reliability from so many of the slow cars we paid a further penalty in points because we ended up closer to the bottom end of the speed scale. If slower cars had finished we'd would have achieved a score higher than the 12 out of 250 we ended up with.

We also paid a 120 second penalty (translating to roughly 36 points, quadrupling what we did get) due to being out of running order, along with half the teams that ran before the final 10. Something that happened because we were held up in fueling due to cars that were ahead in the running order being let through first, we complained to the marshall at the time, but not to event control so we have no leg to stand on officially. But half of the cars in front of us in the running order did not turn up on time either, if they had, we would probably have been half an hour early.

Imho I think that an estimated time bracket with internal running orders shoudl be put in place to avoid the same situation occurring again. That ways long as you turn up before the start of that time slot you are ok, turning up after the start of the slot would incur a penalty, and turning up after the end of the slot a further penalty and the possibility of you not running if no openings become available in subsequent time slots. This last possibility is however unlikely as the slots will most likely be quite generous to ensure things don't overrun. Otherwise If half the cars don't turn up in the first hour, then a team who have estimated they will be going out roughly 2 hours in could be called up an hour early and pay a massive penalty for not being there, which is absurd.

On top of all of this we were initially given a fuel score of -7.5, despite being essentially on par with Huddersfield (who also got a similar negative score) for least fuel consumed by a combustion car (2.7L). As I 'm pretty sure the rules state and show that a negative score is impossible this was somewhat confusing. After explaining that there was a cock up with the spreadsheets a corrected score was put out of 67/100. Which, for the lowest used fuel, is a bit shameful, but I guess that's what happens when you merge two classes that aren't design to be merged and don't put in any correction factors.
Where are the carbon footprint penalties for the battery production?

To add insult to injury when final results were actually posted (which we did not see until waking up this morning due to how long it took), we have not been allocated any fuel efficiency points whatsoever, which, if the 67.3 points awarded on the Endurance results sheet is correct, means that we have been demoted from where we should be in 26th, to 37th!

All in all yet another rather disappointing end to an otherwise good week.

---EDIT---
Having done our own calculation we find out efficiency score to be in fact 71.43, not 67.33 and certainly not nothing. We are confident errors have been made because of Sussex's score: -37.18, despite the rules clearly stating:
D8.22.7 Efficiency scores can range from zero points (0) to positive one hundred (100) points.

[Luniz]

Wow... just wow. FSUK never fails to amaze me in terms of bad organisation and sheer ignorance by some of the officials.

[Bemo]

Originally posted by Thrainer:
The question now is: Will Formula Student change the rules to influence the balance between concepts?

That's the point which makes it completely nonsense have combustion and electric cars within one class.
It is just not possible to compare the efforts of the teams in a reasoble way. It's almost like comparing boats to airplanes. It just doesn't make sense.

Right now with the FS rules it isn't surprising that two electric cars are in front. E-cars have huge advantages in accel and in efficiency. I don't see any field in which the C-cars have comparable advantages.

I don't like the idea of a competition which is changing rules every year to outbalance performances. In my opinion this is just unsatisfying for everyone involved. It is a great thing, that the electric class exists. But that's what it is - another class...

[Kopito]

I agree and disagree Bemo.

I agree that with the current set of rules, the combustion cars don't stand a chance, because they will be slower in Acceleration and AutoX by default, because they have less power and less torque at low rpm. With the efficiency rules changing this year, and it being rewarding for electrical cars to drive fast again, their advantage in endurance, where they basically were able to compensate for the Economy-loss by just driving fast while electric cars had to drive 10% off their AutoX pace to save energy, is gone as well. The only small advantage thats left is cost, but it's marginal.
So under the current ruleset, I agree. However nobody has explained to me why combustion cars (restricted in the way they are atm) were assumed to be competitive with electrical cars (restricted to 85kW). The only reason this discussion arises now, is because an electrical car was finally able to put it together during an overall event.
Personally I like racing against combustion cars, after all they are racecars, so you should be able to compare them.
But I think if it is supposed to be fair, you have to allow combustion cars, to reach a comparable level of power like electric cars, then things could get interesting again.
If things stay like this, and electrical cars become more reliable (although of the top ten autox cars, the two that actually finished endurance were electric...so I could ask you what that says about the combustion cars, after all these years you'd think the finisher rate would be higher...) I think electrical cars winning the combined competitions will become the rule rather than the exception. We will see what happens in Austria...

[Luniz]

I think I am with Bemo on this issue... artificially balancing the performance of the cars would lead to a very complicated ruleset. Just look at FIA-GT or WTCC Rules... Balance of performance issues, weight penalties and all that, it is very easy to be carried away from what you are actually required to do: Build a racecar!

I think the two will never be consistently comparable, you would have to adjust balance rules every other year and that would make it very inconsistent.

Another thing that I find hard to understand: How can the effort of designing a c- or e-powertrain actually be compared in design judging? I can imagine that this is not an easy task, the requirements are just so different!

[bob.paasch]

I agree with Bemo, I think e-cars and c-cars should be in separate classes.

I don't claim clairvoyance, but in 2011 in the thread "Any way to objectively choose engine" I posted this:

Originally posted by bob.paasch:
The next great leap has already happened: electric drive. Until the rules are changed, I doubt we'll see a combustion car win a combined event like FSUK.

and this:

Originally posted by bob.paasch:
We compete under the existant rules, and with the current rules for fuel efficiency equivalent at FSUK, the electric cars are going to be very hard to beat.

and this:

Originally posted by bob.paasch:
IF GFR goes to FSUK, it will be with an electric car.


At the advisor meeting at FSUK 2011, Jon Hilton announced that they would be combining classes for 2012, but that he wanted both c-cars and e-cars to remain competitive so as to not disadvantage teams with limited resources. I told him after the meeting that the electric cars would dominate his competition. I was wrong in 2012, as both AMZ and DUT failed in endurance, otherwise they would have been 1st and 2nd. In 2013, the e-cars were 1st and 2nd, and had DUT finished endurance the e-cars would have filled the podium.

So this is what we get from the official press release on AMZ's win:


Jon Hilton, chairman of Formula Student, said: "Many congratulations to ETH Zurich on their very well deserved win.

"The electrically powered cars have made huge progress going from being unable to complete the 22Km endurance event to winning overall in just five years. We are delighted by this progress but we will have to see what needs to be done in the future to ensure petrol cars remain competitive."

I expect FSUK will modify their efficiency calculation next year to make the c-cars more competitive.

I also expect it will be extremely difficult for a c-car to win FS Austria this year. That won't stop us from trying, of course. http://fsae.com/groupee_common/emoticons/icon_smile.gif http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Z]

Originally posted by Kopito:
.. with the current set of rules, the combustion cars don't stand a chance, because they will be slower in Acceleration and AutoX by default, because they have less power and less torque at low rpm...
Not considering "Efficiency/Economy" for a moment, I have to disagree with the above comments that C-cars "don't stand a chance" against the E-cars.

Powerwise, the limit for C-cars is about 90kW (see extensive discussions elsewhere), versus the 85kW of E-cars. Granted though, the 85kW is probably a lot easier to achieve on the E-cars...

But, as also much discussed elsewhere, outright power is only a small player in FSAE. For instance, the Acceleration event is primarily won with good grip at launch, not max power at the end of the straight. E-cars are currently winning this because they find it easier to fit 4WD (which has the extra benefit of better energy recovery in braking, which is very much needed to minimise their battery weight). But, as pointed out recently on another thread, a well designed 2WD C-car should be comfortably getting into the mid-3 seconds in Acceleration, and 2.9s are feasible.

With regard to E-cars having better low-down torque, this is simply a matter of the C-car teams getting around to building better transmissions. CVTs have been much discussed, but IVTs are even better, and really not that hard (look under most any modern lawnmower, or better yet, tractors!!!). Forget about ancient sportsbike engines with their sequential "gear"-boxes, and move with the times! http://fsae.com/groupee_common/emoticons/icon_smile.gif

The biggest Dynamic event performance improvements in FSAE will come from a lightweight car with maximum aero downforce. I know you students don't believe this yet, but it should be possible for such a car to go fast enough in Enduro that none (or very few) of the current cars would score any performance points (ie. their times would be ~145+% of brown-go-kart+aero's time). The E-cars biggest disadvantage is their weight, and this works directly against them when aero is added (ie. it is a "first order" disadvantage). They wouldn't stand a chance!

Bottom line is that Electric cars are a dead-end. They are not "the future". They are "the past" (read the history books).

So don't let the Rulemakers fiddling with "Efficiency" formulas dissuade you from following what is rationally the best path...

Z

[Kopito]

Dear Z, I am very sorry because this will come across as rude, but I am stunned by the blatant ignorance at display in your comments.


Originally posted by Z:

Not considering "Efficiency/Economy" for a moment, I have to disagree with the above comments that C-cars "don't stand a chance" against the E-cars.

Z

Zurich would have won without the efficiency (>100points margin to the next combustion, Rennteam Stuttgart, I would say we agree they pretty much know how to build winning FS Cars), even scoring very badly in Acceleration (4.0) for a 4WD e-car (technical problems)


Originally posted by Z:

Powerwise, the limit for C-cars is about 90kW (see extensive discussions elsewhere), versus the 85kW of E-cars. Granted though, the 85kW is probably a lot easier to achieve on the E-cars...

But, as also much discussed elsewhere, outright power is only a small player in FSAE. For instance, the Acceleration event is primarily won with good grip at launch, not max power at the end of the straight. E-cars are currently winning this because they find it easier to fit 4WD (which has the extra benefit of better energy recovery in braking, which is very much needed to minimise their battery weight). But, as pointed out recently on another thread, a well designed 2WD C-car should be comfortably getting into the mid-3 seconds in Acceleration, and 2.9s are feasible.

Z

This is interesting. I am sorry I didnt read that post, but I guess some c-Teams should, because apparently they are all completely incompetent, if it is "comfortably" achievable and nobody has managed in almost 25years this competition exists. We saw Delft (4WD e, 150kg) with a 3.45 on the first accel run at FSG2012 (cold tires), more than 4 tenths faster than the best combustion car that day.


Originally posted by Z:

With regard to E-cars having better low-down torque, this is simply a matter of the C-car teams getting around to building better transmissions. CVTs have been much discussed, but IVTs are even better, and really not that hard (look under most any modern lawnmower, or better yet, tractors!!!). Forget about ancient sportsbike engines with their sequential "gear"-boxes, and move with the times! http://fsae.com/groupee_common/emoticons/icon_smile.gif

Z

Come talk to me again if you have found or built a 180kg FS car (165kg without Aero) that has 350Nm at each of it's four wheels at 0rpm.


Originally posted by Z:

The biggest Dynamic event performance improvements in FSAE will come from a lightweight car with maximum aero downforce. I know you students don't believe this yet, but it should be possible for such a car to go fast enough in Enduro that none (or very few) of the current cars would score any performance points (ie. their times would be ~145+% of brown-go-kart+aero's time). The E-cars biggest disadvantage is their weight, and this works directly against them when aero is added (ie. it is a "first order" disadvantage). They wouldn't stand a chance!

Z

If you have gotten near a laptime or overall points simulation for one event, you will see that its not a easy as more Cz, less kg, and everybody will be happy... I know Monash is destroying everything in Australia, and I personally think they are great guys that build cars that are inspiring, but they will tell you, that the moment electric cars put wings on, they had no chance to win any dynamic event other than skidpad.
I personally believe that a 4WD electric car with a Cz of >3 and enough energy on board to drive an endurance faster than combustion cars can be made <170kg (I am sure we will see it next year).
Look at the event handbooks, and youll see that electric cars, are not one bit heavier than their combustion competition. if you build an ultralight FS Car with lots of downforce, you might get around 150kg this probably using 1-cyl engine, where an electric 4WD car with comparable DF will way around 170kg. Trust me, the electric car will do below 3.5 in accel, probably win skidpad (same DF + 4WD Torque Vectoring..not mentioned to this point), smash the c-car in autoX (much more torque + more traction + same DF + Torque Vectoring + easier to drive). The e-car will be able to coast in endurance and would win overall (efficiency out of the equation..we agree that this adds a further advantage)


Originally posted by Z:

Bottom line is that Electric cars are a dead-end. They are not "the future". They are "the past" (read the history books).

So don't let the Rulemakers fiddling with "Efficiency" formulas dissuade you from following what is rationally the best path...

Z

None of the e-teams want to save the world. None of them are "green". Nobody in FS wants to solve global warming but built the fastest possible car under the current rules. This is not a forum to discuss where the future of mobility lies, this is an FS Forum.
And I am very sorry, but under the current ruleset (even taking efficiency out of the equation, talking purely real dynamics), a well built electric car will smash a well built c-car. I sincerely invite you to come to germany this year to see for yourself (already last year the two best AutoX Times at FSG were posted by a 4WD-non-winged and a 2WD-winged electro, distancing the best c-car by a second (75s-Lap).

[Bemo]

Once more Z is coming around, telling how stupid all people involved in this competition are. Has anyone ever seen anything that guy built? I'm really curious to see these "comfortably" achieved 90kW in a rules-compliant c-car for example...

[Stef de Jong]

Bottom line is that Electric cars are a dead-end. They are not "the future". They are "the past" (read the history books).

Z, really? Might want to consider the operational costs/energy usage and maintainability and add the tremendous performance... Heard anything about a small California car maker named Tesla lately?

[Simon Dingle]

While it's somewhat off-topic, I think Z's probably right on the power front.

I seem to remeber the isentropic mass flow rate of a 20mm restrictor being 73g/s.

Plug in an air-fuel ratio of 0.9 and you get a fuel flow rate of 5.5g/s.

Gasoline has an energy density of 46 MJ/kg. So plug that in and you get a maximum chemical potential energy flow rate (power) of 253kJ/s (253kW).

Now I I'm not saying that this figure is possible. As I'm sure you're all aware ther are all sorts of losses involved in converting that chemical energy to mechanical energy, but 90kW of mechanical energy equates to a thermal efficiency of 35.6%. To give that figure some context it's about the same as that of a current F1 car at full power.

So with the same engine concept as an F1 car, it seems pretty difficult. However, an F1 car gets that kind of efficiency at 18,000rpm, while an FS car would make it at <12,000rpm. Since frictional losses increase exponentially with engine speed an FS car would have an efficiency advantage there. Plus, an FS car can use a turbo to further expand the exhaust gas and therefore has another possible efficiency advantage. The turbo also gets you an added efficiency bonus in that you can choke the restrictor at lower engine speed and make your 90kW where the fritional losses are smaller.

If you're curious as to what's possible in terms of IC engine efficiency, lookup 2-stroke diesel engines as they have an thermal effciency of around 50%.

I'm going to say that I'm confident that 90kW is possible from an FS engine, but maybe isn't easy. I think it would probably involve abandoning the beloved motorbike engines and going for a different concept.

EDITTED for a typo that meant I accidently said 250kW from an FS engie is possible :P

[Simon Dingle]

ps hopefully I haven't made any numerical mistakes, but please let me know if I have http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Jan_Dressler]

Originally posted by Simon Dingle:
Plus, an FS car can use a turbo to further expand the exhaust gas and therefore has another possible efficiency advantage. The turbo also gets you an added efficiency bonus in that you can choke the restrictor at lower engine speed and make your 90kW where the fritional losses are smaller.
Turbocompounding is also allowed by the rules...

[Bemo]

From where do you have the ~35% efficiency of an F1 engine?? I doubt that number. For a gasoline engine this is a very high efficiency and I've never heard of such efficiency numbers at such high engine speeds. Unfortunately no F1 team will tell, what efficiency they really reach.

And you should be aware that assuming stuff like isentropic mass flow in the restrictor is also quite an idealised assumption. I didn't recalculate your numbers, but they show quite nice how idealised all your numbers have to be to reach a power level which Z considers to be comfortably achievable.
In 25 years of FSAE no team ever got near such a number. So if you REALLY want to tell this is "comfortably achievable" you should demonstrate it...

[Simon Dingle]

Hi Bemo,

I was slightly surprised myself, so I'm happy to be corrected if I'm wrong.

I calculated the efficiency in the same way that I did for checking Z's 90kW.

F1 are regulated to 2.4L displacement, 18,000rpm and normally aspirated. So that (roughly) defines the upper limit for mass flow rate of air (+5% for ram air effect at 300kph). I made that to be 378L/s or 463g/s of air.

Assuming a lambda value of 0.9, the mass flow rate of fuel comes out at 35.2g/s. Gasoline's energy density is 46MJ/kg. So that works out to be 1621kW of chemical power.

Mercedes AMG list their power as ">750PS" so that's about 547.5kW. One over the other is ~34%.

I think my working is good, albeit with a few assumptions. Let me know if you think I've got anything wildly wrong.

Cheers,

[Owen Thomas]

The math certainly looks solid, but I just don't see these two engine types as similar enough. There's got to be a reason an F1 engine costs >10x what your typical FSAE donor vehicle costs. Not to mention the design goals are entirely different. F1 engines are designed for peak power, and are strung out much, much closer to their absolute capacity than a usual FS engine, which is designed to be controllable by biker-Joe and last tens of thousands of kilometers without a rebuild.

I could see a maximum efficiency closer to 30% as being reasonable, which with your math gives ~101bhp (76kW). The highest I've heard is around 95hp; of course it was an in-house dyno and all things considered is probably a lie, but never the less it is close. I really think the key here is that it's a maximum efficiency that we're looking at. Again, these engines aren't designed to stretch the maximums, and sacrifice peak volumetric efficiency for gains elsewhere in the RPM range.

Back to the argument at hand, I agree that e-vehicles have a power advantage. The key thing though is the torque control. 100% of peak torque at 0 RPM is certainly useful, and I'm guessing the good electric vehicles control wheelspin with a smart PWM program on launch to make it even better. Tuning an engine for peak power and running a finely calibrated CVT (or IVT) seems to be the closest an IC car can get to this sort of thing.

I would also argue about electric vehicles as a "dead end". Historically, they have not done well, but modern technology is quite an amazing thing. Plus, the general public see e-cars as "green", and I can guarantee you that if there's a market for something, it will be produced and sold, then improved and sold again. However, I definitely agree that choosing your vehicle concept to accomodate 10% of the points because it is trending is not rational. Right now, though, it seems that a well-made e-car outperforms a well-made IC car. I suspect rule changes will be coming if SAE intends to keep a single class.

[Thijs]

Z,
assuming you actually could get 90kW from an engine, who cares? Acceleration is won or lost at the starting line, long before you're power limited.
Case in point: There have been plenty of high powered ICE cars at Hockenheim. In eight years not a single one got under 3.8 seconds, only 5 got below 3.9.
Meanwhile, DUT12 only used 55kW, yet managed 3.45.

Good luck coming up with a lightweight CVT and traction control that can match the smooth torque delivery of an electric motor right from the start.

For FSAE, I don't really care how much air could theoretically flow through a restrictor. The extra 5kW compared to the max power of an electric car will not bring you anything in any realistic scenario. Of course in a world where combustion cars can apparently accelerate at >1.8G from start to finish line, reaching about 186km/h in the process (your claim of 75m being possible in 2.9 seconds), we can argue about that forever.
Which I’m sure you will.

Thijs
Delft

PS. On topic, Congrats to Zürich!

[Z]

Kopito, Bemo, Stef de jong,

You guys really are idiots! Which, very sadly, means you are well on your way to becoming perfectly typical Engineers; "Oh, no, no, no... That will never work! I know all about these things, you see, ... because I calculated it, and I are an Engineer!"

Along with being a disgrace to your chosen profession, you apparently can't even read. I covered maximum power and the Acceleration event barely a month ago on the Michigan 2013 thread, starting on page 10. (http://fsae.com/eve/forums/a/tpc/f/825607348/m/91720558151?r=69220468151#69220468151)

The really disgraceful part is that I am told that you students are nowadays taught some sort of subject called "Systems Engineering". This appears to be nothing more than a collection of bulldust buzz-phrases, intended to obfuscate what used to be a common sense approach to doing things. Anyway, one of the buzz-words is "Benchmarking", meaning nothing more than checking what others are doing, or have done (ie. "doing your homework").

If any of you had done that, then you would know how much power literally thousands of other racecars, for many, many decades, have been getting through their restictors (or just read page 11 of above thread). (For anyone else interested, the power figures of the recent Le Mans cars will be coming out soon. Typically these are around 35 hp/sq.cm.restictor, for the 24+ hr, 5,000+ km engines.)

And regarding the Acceleration event, if any of you can drag yourselves out of your ivory towers (or take time off from calculating Claude's 59+ Damper "magic numbers") and get down to your local dragstrip, then the toothless hillbillies there might be kind enough to educate you as to what is important in drag-racing. Ie, Learn the difference between TRACTION-LIMITED and POWER-LIMITED!!! (Bemo, a ~50kW car will "comfortably" do ~3.5s FSAE Acceleration runs. This is the simplest to understand straight-line Mechanics that is taught in secondary schools!!! http://fsae.com/groupee_common/emoticons/icon_rolleyes.gif)
~~~~~o0o~~~~~

Simon,

Here is a cut-and-paste from a post I sent someone a few years ago (the post also included the typical empirical figures).

"My old textbooks give maximum (choked) mass flow through a nozzle as,

M-dot = 0.0404 x AreaThroat x Pressure / (sqrt(TempKelvin)) kg/s.

There are other equations, but this one is in terms of easily measurable atmospheric pressure and temperature. This gives,

Mass-flow/sq.cm-restrictor = 0.024 kg/s (same as your weblink).

Good quality (ie. racing) gasoline fuel has energy-content = ~47 Mj/kg, and stoichiometric air/fuel ratio = 14.7, giving,

Power/sq.cm-restrictor = ~77 kw x overall-engine-efficiency.

So with ~35hp/sq.cm, ie. 26kW/sq.cm, efficiency = 26/77 = 34%.

Or with ~40hp/sq.cm, ie. 30kW/sq.cm, efficiency = 30/77 = 39%.

The 34% figure is quite believable, given that these engines have very high compression ratios (13-15+:1), and are built with minimal internal friction.

The 39% figure also makes sense as a practical limit for four-stroke SI engines."

So, pretty much the same as your calcs. The biggest variables are fuel-energy-content + stoichiometric-ratio for the given hydrocarbon fuel, and overall efficiency (although cold days also help a bit).

If FSAE really wants to encourage good engineering, then they should allow all types of combustion cars, especially two-stroke diesels (as you mentioned). Then the E-cars really would "not stand a chance"! http://fsae.com/groupee_common/emoticons/icon_smile.gif

Z

(Edit: Just saw last post. Thijs, you are right about "at the start line" vs "power limited" (about time someone gets it!). Now if you go and talk to some of those toothless hillbillies at the drag-strip, then you might learn how to get below 3 seconds (although I have already explained that...).)

[bob.paasch]

Originally posted by Owen Thomas:
Right now, though, it seems that a well-made e-car outperforms a well-made IC car. I suspect rule changes will be coming if SAE intends to keep a single class.

I've talked with SAE CDS staff, they have no intention of running the e-cars with the c-cars in North America. The two competitions that I know run the two classes together are FSUK and FS Austria (the later otherwise known as FSNK: No Kangaroos) http://fsae.com/groupee_common/emoticons/icon_smile.gif

FS Austria started as a combustion competition in 2009, then let e-cars enter and run with the c-cars in 2011. I think the single class at FSA is mostly convenience.

FSUK, on the other hand, had two classes until 2012: class 1 "c-car" and class 1A "all other" (ignoring class 2 for the sake of this discussion). IMECHE made a conscious decision to combine two existing classes, with the caveat that both classes would remain competitive. I disagreed with that decision in 2011, and I disagree now. I agree with Bemo and Luniz, combining classes is nonsense and changing the rules every year to advantage or disadvantage one set of cars or another is inconsistent.

On the other hand, GFR builds both an e-car and a c-car. So if we ever return to FSUK in the future I guess we can go with the car that the rules advantage that year. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Kopito]

Originally posted by Z:
Kopito, Bemo, Stef de jong,

You guys really are idiots! Which, very sadly, means you are well on your way to becoming perfectly typical Engineers; "Oh, no, no, no... That will never work! I know all about these things, you see, ... because I calculated it, and I are an Engineer!"



That's classy...anyways I won't argue with you about your tone, because as I am an Idiot, I am wondering, why, if you are so smart and know so much, you have so much time bashing "us students" (which most of us aren't anymore btw).
Two suggestions:
1. Get a job, and put your "tremendous" knowledge into use. I am stunned that somebody who is so smart, that he calls three people, that have all been responsible for some of the fastest FS-Cars from the past 5 years "idiots" (with regard to FS), still has the time to "live" in this forum... go on get that nobel prize!
2. PLEASE build a FS-Car!!!! (or have some of your underlings do it, as I am sure you have some, the way you talk down to "us students") If you do that, and it achieves all those goals that you describe as "comfortably" achievable, I'll come to Australia and watch it. I am sure Bemo and Stef will join.

[Bemo]

Definitely I would love to see that car!

BTW I'm not a student anymore (I took part in the competition three years ago. Right now I'm working for Porsche Motorsports and am involved in this year's Le Mans car you are so looking forward to see the power numbers http://fsae.com/groupee_common/emoticons/icon_wink.gif

Just comparing the ratio of power and restrictor area is quite a tremendous simplification as you loose quite a lot of mass flow near the restrictor walls. This effect is much bigger for smaller restrictors like in FS.

BTW: I'm not sure what Kopito's position in his team was. But you're definitely the first one calling two former team captains of winning teams idiots within one sentence.
We showed up with our efforts and competed (and won). What have you done?

"I know all about these things, you see, ... because I calculated it, and I are an Engineer!"

Funny you are critising others with these words. We have built something. You're the one who just tells others what is possible and what you have calculated.

Build that 90kW C-car which is doing acceleration runs in 3.0s. I promise, I will come to Australia and all your drinks are on me for a month if you manage to keep your promises.
As all this is "comfortably achievable" I don't see any reason, you shouldn't do this.

And to get back to topic: Congratulations to Zürich, really nice job, although according to Z it was quite simple as all the others (without any exception) are just morons.

[Thijs]

Z,

Of course when I said ‘Combustion car‘, I meant ‘FSAE (combustion) car’.
I’m aware of what top fuel dragsters can do with their >5MW engines, but I didn’t think you would really draw that parallel. Fun fact: apparently these things create 3.5kN of downforce from standstill from their upward directed exhausts alone.
Since you’ve repeated the 2.9 seconds claim on multiple threads now, I’d like to press you on it though.

Consider the following car:
-65% rear weight (that’s your number)
-Wheelbase 1525 mm (I wouldn’t want to take a slalom in a top fuel dragster)
-CoG height at 260mm (that’s fairly generous)
Now comes the good part:
-Its tires somehow have unlimited traction
-90kW available at the wheels whenever you want it
-It does not suffer from mundane things like drag. All this power goes purely into accelerating the car
-200 kg including driver

Unless you propose wheelie bars, this thing will simply fall over at accelerations over 0.35*1525/260=2G, so let’s take that as our continuous acceleration up until the point where we’re power limited.

You can write your own code, but take it from me that this car will cover exactly 75 meters in 2.9 seconds, crossing the finish line at ~164km/h.
Are you suggesting this is a car that can actually be built?

Anyway, I’m off writing mr. Royce an email asking him to consider introducing nitromethane.

Thijs
Delft

[JulianH]

Wow, what a discussion...

Bemo, behind "Kopito" is our last year's team leader, so there are three team captain's of winning teams... http://fsae.com/groupee_common/emoticons/icon_smile.gif

About the competition:
We had a very difficult Saturday with an electrical problem which basically ruined Acceleration and SkidPad. (I drove the two sensational 28s and 14s runs, it felt horrible) and again the 4th Sprint/AutoX run. Luckily we could fix it and survive the cruel Endurance run.

Sadly our fellow 4WD teams couldn't manage it for different reasons.

It is a difficult discussion about electric vs. combustion cars. Yes, there are like 5-6 Electric cars out there that can perform with the best combustion cars (At UK 2013, the combustions from Stuttgart, Munich and Karlsruhe didn't have a perfect event and the 4WD monsters probably would have won even without Efficiency) But if one looks at the AutoX of FSG 2012, the 7th placed car is nearly 9 seconds down of our time and that was a 2WD car..

I think it is not possible to have a rule-set where the eCars can run with the cCars without the rules changing every 1 or 2 years. Splitting the classes (again) is probably the only option for the future.

Edit: Ah I forgot... Z, we will try to get our "car from the past" down-under for a little drag race with your creation if it is ready, I think the Delft-guys will share a container with us http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Bemo]

It'll be very interesting seeing all these cars at Hockenheim. As the competition is later in the year, the cars are usually much better tested and therefore more reliable and faster (as far as I know only two of the top 10 AutoX cars were able to finish Endurance).

It would be quite interesting to calculate the theoretical result of a combined class after Hockenheim.

I will be there myself as scrutineer, so make sure your car is well prepared and rules compliant http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Stef de Jong]

Originally posted by Z:
Kopito, Bemo, Stef de jong,

You guys really are idiots!

Don't know Kopito, but you are absolutely right about Bemo and me though http://fsae.com/groupee_common/emoticons/icon_smile.gif.


Originally posted by Z:
The really disgraceful part is that I am told that you students are nowadays taught some sort of subject called "Systems Engineering".

True that it may be some sort of a buzz-word. Here's the catch: ANY teammember that has been around long enough in ANY succesfull team will tell you that the REAL FSAE challenge lies in getting a proper organisation in order to be able to get anywhere near a high performance and balanced design and proper scoring at events.

Otherwise you should really talk to alumni of teams like Stuttgart, GFR, Muchen, ETH, ETS, ... Oh yeah, you might want to listen to Delft alumni on this too.


Originally posted by Z:
Thijs, you are right <...> Now if you go and talk to some of those toothless hillbillies at the drag-strip

See you tonight Thijs, please do talk some sense into me http://fsae.com/groupee_common/emoticons/icon_wink.gif


Originally posted by Thijs:
Unless you propose wheelie bars, this thing will simply fall over at accelerations over 0.35*1525/260=2G, so let’s take that as our continuous acceleration up until the point where we’re power limited.

You can write your own code, but take it from me that this car will cover exactly 75 meters in 2.9 seconds, crossing the finish line at ~164km/h.
Are you suggesting this is a car that can actually be built?

Brilliant as always dude.

PS. @Bemo, technically speaking my team did not win an event (damn you Stuttgart!), but we did give you a hell of a fight didn't we? http://fsae.com/groupee_common/emoticons/icon_wink.gif We did secure 2 Design and various other Awards.

[Bemo]

Pff, at FS UK we were more than 5 points in front of you - you call that a fight? http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[mdavis]

Originally posted by Bemo:
It'll be very interesting seeing all these cars at Hockenheim.

This. There will also be a couple of very fast cars from this side of the Atlantic in Germany as well. I can't wait to watch the live feed of autocross and endurance.

[Fantomas]

Guys,
you should have learned not to feed the troll aka. Z. He has been banned from this forum before and that was for good reasons.
Additionally he seems to be someone who has lots of time to spend on this forum and give "advice" to people competing in a competition which he has never attended. Making claims he always fails to prove, probably being frustrated that no one ever listens to his advice...
He has also never gotten the chance to participate in an FS/FSAE competition as a volunteer/design judge for good reasons as well. His teachers usually wrote in his "reports" that "he is not getting along well with others".
Just do like I do and ignore him and his posts. This will be the hardest punishment for him, because he tries so desperately to be heard in this forum that probably no one is listening to him in the real world.

Fantomas

[Thijs]

Fantomas,

http://imgs.xkcd.com/comics/duty_calls.png

Thijs

[Fantomas]

Exactly that kind of guy is Z in my opinion.

[Markus]

This is some sweet stuff. http://stratics.com/community/data/images/smilies/popcorn.gif

Too bad they're missing the popcorn eating smiley on this site (time to upgrade?!!!).

[Z]

http://imgs.xkcd.com/comics/duty_calls.png

So I better set things right! http://fsae.com/groupee_common/emoticons/icon_smile.gif

It starts with Bemo making his engineering decisions (calculations?) based on reasoning like,
"In 25 years of FSAE no team ever got near such a number."
So, if it ain't been done in the past, then it definitely can't be done in the future! (Err, even if all the toothless hillbillies are doing it right now, and have done for ages!)

Then a lot of school kids get upset because Horrible Old Guy calls them slow, and stupid, and BORING! (Or is that "Homeless"OG. Whatever, HOG sounds nice.) And, as usual, Fantomas gets all his facts wrong.

Just to show you how boring you all are, here is a 2005 thread "FASTEST EVER ACCEL TIME..." (http://fsae.com/eve/forums/a/tpc/f/125607348/m/61210643621/p/1) that covers this same subject. There you can see that there has been very little progress in Acceleration times since as far back as 2001. The way forward to faster times was spelled out quite clearly back then, but I guess you all find it much more comfortable doing the same-old, same-old...

But then Thijs starts thinking about the problem.
"Consider the following car:
-65% rear weight (that’s your number)
-Wheelbase 1525 mm (I wouldn’t want to take a slalom in a top fuel dragster)
-CoG height at 260mm (that’s fairly generous)
Now comes the good part:
-Its tires somehow have unlimited traction
-90kW available at the wheels whenever you want it
-It does not suffer from mundane things like drag. All this power goes purely into accelerating the car
-200 kg including driver

Unless you propose wheelie bars, this thing will simply fall over at accelerations over 0.35*1525/260=2G, so let’s take that as our continuous acceleration up until the point where we’re power limited.

You can write your own code, but take it from me that this car will cover exactly 75 meters in 2.9 seconds, crossing the finish line at ~164km/h.
Are you suggesting this is a car that can actually be built?"

And, in fact, Thijs himself suggests that this is a car that can actually do 2.9s over 75 metres (well, he gets some bits wrong, but see below).
~~~o0o~~~

So which is it?

Bemo's "It can't be done, because it has never been done.".

Or Thijs's "It might be possible to do a 2.9s time, IF.....".

Or, to put it another way, when will you young people STOP BEING SO BORING, and start doing some interesting stuff! http://fsae.com/groupee_common/emoticons/icon_biggrin.gif
~~~o0o~~~

Thijs,

In your first post you said,
"... in a world where combustion cars can apparently accelerate at >1.8G from start to finish line, reaching about 186km/h in the process (your claim of 75m being possible in 2.9 seconds)..."
So, you considered a constant acceleration over the whole distance (D = half*A*T^2), even though that requires an excessive amount of power at the end of the run.

You must then have spent some time talking to the hillbillies, because in your later post (up above) you consider more Gs at the start, then power limited at the end (ie. Gs drop off). But then this bit.
"... this thing will simply fall over at accelerations over 0.35*1525/260=2G,"

Really? Just "fall over..."?? Is this some sort of magical car that has no inertial resistance to pitch motions about the rear-wheel???

If you spend more time with the hillbillies (they're quite friendly, and harmless, well ... toothless at least...), or else just watch them, you will see that all the fast cars "lift" as they launch. Think Olympic sprinter, crouched at the start line, then pushing DOWN and back. Anyway, the extra rear-tyre load (Fz) from this means the initial Gs can be considerably higher than 2G.

Many drag-cars manage well above 4G at launch, but retry your calcs with, say, just 2.5G for the first half-second. I don't know why you need "code" for this, but my sketch-on-a-post-it-note (V vs T) suggests that sub-3 second times are possible with a final speed of under 40m/s (<<144kph), and only about 75kW power required (aero drag included in calcs!).
~~~o0o~~~

Bottom line is that the first team that does an officially timed 2.999 second Acceleration run, doesn't matter where, doesn't matter if they never achieve that time again, will forevermore be a household name for being THE FIRST EVER TEAM IN THE 2 SECOND BRACKET!!! (Err, well, "household name" in the smallish FSAE community).

Or else you can keep being BORING, forevermore... http://fsae.com/groupee_common/emoticons/icon_smile.gif

Z

[MCoach]

"I reckon that is there was a drag racing class for cars similar to FSAE, they would design their cars completely different. After all, 100% of their points would come from the drag racing event, not 7.5%. I would also bet those cars would suck in an autocross.

Sam Zimmerman"

Quoted from 8 years ago. Boring just means that our calculations are correct and we get no surprises. Things just go according to plan. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Thijs]

Z,

Looking at its other properties I think we can agree that it would indeed be a pretty magical car http://fsae.com/groupee_common/emoticons/icon_smile.gif

I'll just take your post as a yes to my previous question:


Originally posted by Thijs:
Are you suggesting this is a car that can actually be built?


I'd say you have all your work still ahead of you, explaining how you'd build tires that give you the 2G's you'd need to lift the nose of the car without downforce or burnouts.

You can be sure I'll be on that plane with Bemo and Julian as soon as you call http://fsae.com/groupee_common/emoticons/icon_smile.gif

Thijs

[Michael Royce]

Thijs,
Nitro?? Forget it!!! I would not touch that stuff with a 10 foot pole (to use an old English expression). Anyway, Dr. Andrew Deakin is now chairman of the FSAE Rules Committee, so anything you write to me goes (almost) nowhere.

[Thijs]

Originally posted by Michael Royce:
Nitro?? Forget it!!!

I'm glad we agree, I was of course kidding http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Bill_Murray]

https://81322ee9-a-62cb3a1a-s-sites.googlegroups.com/site/formulastudentdrag/home/FSDrag!.png?attachauth=ANoY7cqW_5e-riEzjtw6A3YhnP41UIU87SjympWcAZvQjQVHW_0YsIqmPAad1b BON9s8Zcw4_4QoCWnU_uqhvpfWPXFgiAt6LAaQdBBeWNM9NEwv _18TujQ81i9wLjJ_-_SlmfB-lXQt2M_AdI-yubQIn6KyhfJ_wqVPnx5Ca2xuanoQFCrrStxh2qXKoM_Tky36Q GagEABMgBKxKkHC5fJ_ERCcHQPfYAc1LK_s-aKjNO3Cuf3sNlA%3D&attredirects=0

[Trevor]

Originally posted by Bill_Murray:
https://81322ee9-a-62cb3a1a-s-sites.googlegroups.com/site/formulastudentdrag/home/FSDrag!.png?attachauth=ANoY7cqW_5e-riEzjtw6A3YhnP41UIU87SjympWcAZvQjQVHW_0YsIqmPAad1b BON9s8Zcw4_4QoCWnU_uqhvpfWPXFgiAt6LAaQdBBeWNM9NEwv _18TujQ81i9wLjJ_-_SlmfB-lXQt2M_AdI-yubQIn6KyhfJ_wqVPnx5Ca2xuanoQFCrrStxh2qXKoM_Tky36Q GagEABMgBKxKkHC5fJ_ERCcHQPfYAc1LK_s-aKjNO3Cuf3sNlA%3D&attredirects=0

http://fsae.com/groupee_common/emoticons/icon_biggrin.gif hahah you know your teeth are stealing all your brainpower

FSAE.com, where the real engineering is buried beneath A+ trolling and "How do I design suspension" threads http://fsae.com/groupee_common/emoticons/icon_wink.gif http://fsae.com/groupee_common/emoticons/icon_wink.gif http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Z]

https://81322ee9-a-62cb3a1a-s-sites.googlegroups.com/site/formulastudentdrag/home/FSDrag!.png
Bill,

I don't get it???

The picture is upside-down, and I was expecting to see lots of toothless grinning! http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

Z

[JSR]

I took some photos during the weekend, which you can find here: http://rejsa.nu/forum/viewtopic.php?t=90257

This is just a small sample, and if anyone wants some photos of their car, just send me a pm and I will see what I can find.