2015 FSAE Rules

[apalrd]

1100C EGTs shouldn't exist on any engine, not just turbo engines.

I don't think that allowing the throttle to move for forced induction engines is a sudden reason for teams to turbocharge. As is, you can build a very good turbocharged powertrain with the throttle upstream of the restrictor. It's not a huge thing turning the vast majority of teams away from turbochargers, you can get over the transient issues with good controls. Moving the throttle helps teams get over the compressor vacuum and some transient issues that turbos see, and lets teams put the throttle in the industry-standard location for turbocharged engines.

Moving the throttle is a little help to turbo teams but in no way requires that a good team turbocharges to stay competitive.

[Alumni]

Snowmobile engines are far more enclosed than any ATV or formula car i've ever seen. Particularly at CSC where there is dynamat and other sound deadening materials lining the engine bay several layers thick.

I'd bet that the total inlet area on a snowmobile for air passing through the engine bay is not much more than 1sqft.

[Bemo]

Is there anywhere an official document available or are these just rumors. Before starting to make an opinion I'd like to see the real wording ;-)

[mech5496]

No Bemo, there is not. Those were discussed in the 2015 rules briefing during FSUK and are just thoughts for the moment, some of them to be implemented much later than 2015.

[Dunk Mckay]

I'd like to add that I find it very strange that having made the progression to a 2 year rules cycle that now no draft rules are being released and the final rules are coming out later than previously... Surely one of the reasons for doing a 2 year cycle is to get the rules out to teams earlier in their development cycle. Which for most European teams at least should really already have started for the 2015 competition.

[GXP_Matt]

I was thinking about this on my flight today. If the goal of the new rules is to encourage the use of turbos (which is the obvious choice when the order of turbo > throttle becomes the industry standard), then I hope there are additional fire safety rules added. Here is my line of thought, and I am kind of think out loud here.

Under the current rules set, turbo teams have a chore in keeping their systems well oiled under vacuum. Because their oiling systems, and therefore cooling systems, for the turbos are in non-ideal conditions, these teams are forced to either go for max performance and risk overheating and fire or minimize their risk and have an 'underperforming' turbo.

TLDR: Changing the current turbo rules to 'industry standard' type rules will cause there to be many more half-attempts at turbocharging and result in many more fires.

I'll have to disagree with you here. Under the current rule set, it isn't a problem keeping the turbo well oiled, it's that the turbo is TOO well-oiled! With the throttle in front of the compressor, whenever the plate is closed you have a large vacuum in front of the compressor wheel, which pulls oil through the piston rings that seal the turbo shaft. So at idle or under braking for a corner you are just pulling oil through the comp seals and burning it, unless you can pull significant vacuum on the turbo oil drain at all times.

Now if FSAE was to switch to restrictor-> turbo-> throttle, you would greatly reduce the situations where you are pulling oil through the turbo seals since the compressor stage wouldn't see nearly the vacuum at idle or on the overrun. I would say that this arrangement actually reduces the chances of a thermal event since you don't have big pools of oil sitting in your compressor housing or intake plenum. It actually makes it easier for someone to make a half-attempt at turbocharging since you don't need to scavenge the turbo's oil drain, you can just run a high pressure oil line to the top and a normal drain to the bottom. You'd still want to scavenge the turbo if you mounted it below the oil level in the sump since it wouldn't drain very well that way, but you wouldn't need as much vacuum.

I'd be happy to dispel any other fears you have about turbocharging an FSAE car- I think if these rules go through it would make way more sense for a lot of teams. I would urge people to not try and skimp on weight savings on the turbo manifold, especially if you are using the manifold to fully support the turbo. Mount the turbo close to the cylinder head for good usage of exhaust pulse energy, make the manifold out of thick stainless, run a nice oil drain, and then all you have to figure out is a boost control strategy and how much boost your engine will take Oh, and the GT12 is too big for FSAE engines.

[Mumpitz]

Swiftus, why the portrayal of turbochargers as grenades with the pin pulled? You know what spins fast, is filled with flammable liquids, and spews extremely hot gasses? An engine, yet the turbo is being portrayed as the evil monster that is certain incinerate any car it comes near. Don't want to run one for the perceived risk? OK don't, but don't tell others that they shouldn't be allowed to either. Almost all thermal events that I have witnessed at competition or heard about have been attributed to either oil or fuel leaks as the root cause. What's the difference between the inexperienced team running 1100C EGTs on a turbo car or the inexperienced team running 900C EGTs N/A? What does it matter when it's already glowing red? If anything an N/A exhaust typically has more hot exhaust surface area exposed since the turbo is capturing that thermal energy early on in the system.
1100C may not make your exhaust bridge very happy and may lead to very premature seat damage but it's not apocalyptic. Current production turbos are designed to operate at 1050C sustained to reduce the need for boost enrichment.
If you don't want to keep the flames on the paint job and off the car build a robust fuel and oiling system.
*I should mention I have 0.000 stake for or against the use of turbos. I am an alumni of a team (Oakland Univ.) that doesn't run a turbo and, as far as I know, doesn't have plans to run one in the near future. I am just a proponent of freedom and racecars though. You do like freedom and racecars don't you? :P
This is also why I don't support the talk of banning unsprung aero. No one is proposing banning unsprung corners of the car yet which has more mass? More effect on vehicle control? Potential danger to course workers and spectators?

Suspension/wheel failure: corner flies off, brakes and steering lost, wheel assembly goes for a long journey until it hits something or eventually dissipates all it's energy.

Wing failure (sprung or not): Wing flops over or falls off. Massive surface area and low mass bring it to an abrupt halt. The arguments about car stability are irrelevant. Wing falls off there is no concern about vehicle handling, the black flag flies.

Are we more concerned with safety or perceived safety? It seems like someone wrote a FMEA for the comp and had their grandma read it. "Won't you crash like a plane if your wing falls off!!!" "A turbo spins how fast???" "1100C! no more racecar for you, I'll heat up some tea for us and we can watch my soaps" (proceeds to light her Virginia Slim off the blue flame of the gas burner).

[Mbirt]

Haha thanks for the great lunchtime read, John. It's good to hear some more voices of reason here. I too was afraid of turbos before I got a chance to implement one on the Clean Snowmobile project. I'm glad I did because I got to travel to Taiwan to present the SETC paper born from it and that got us on the cover of Momentum.

Jay, here's the extent of the bodywork openings of a typical Clean Snowmobile:


Here's what lies under that bodywork:




Pass-by WOT noise is worth 300 points at the competition, so you might imagine how much foam/dynamat/etc also gets shoved in and around the engine compartment. The competition still gets insured to have the sleds held at peak power speed WOT for 2 minutes in a lab test and to have volunteer judges climb abord them and bomb around a handling course (with JUMPS!).

I'm surprised that GFR's points simulations show that a particular powertrain will be so dominating under more restrictive aero rules. Let's call this the Wisconsin-Madison car. With a very well developed turbocharged single cylinder powertrain, has this car ever had a distinct advantage due to that particular subsystem? I think history has shown that teams with great powertrain capabilities haven't ever been a threat to teams with more important project management/vehicle dynamics/driver capabilities.

[Z]

Kev and Dunk,

Thank you both for your thoughtful replies.

My (mildly? ) heated last post was a by-product of some recent discussions with some academics at the local Uni, where it dawned on me that they really do believe that the world is flat (metaphorically speaking, in a non-FSAE field). The derisory snorts they made when I suggested that the world is round (again, metaphorically) didn't help. But even worse was their complete disinterest in any sort of rational discussion of flat-earth vs round-earth theories.

I have now found this to be the case in several different fields. The Emeritus Professors honestly believe that they can teach anything they want, without ever having to give a rational justification of their teachings. The Education system is now a free-for-all with no quality control system to catch mistakes (and the above Professors are making some atrocious mistakes!).

That is why I like competitions like FSAE, because the stop-watch provides the error-checking procedure that decides which answers are more, or less, correct. I stand by my comments (on another tread) that in the most objective FSAE events, namely Acceleration and Skid-Pad, the "(in)correctness" of the answers has hardly changed in ~30 years. The bell-curve has got higher and wider, but its centre has not shifted.

This implies a lack of "learning" by the overall FSAE community. Or at a more local level, a lack of an effective "education process" from older team members (and supervisors) to the newbies. There are, of course, exceptions, such as yourselves and the other successful teams (eg. Monash, GFR, Stuttgart, Delft, Zurich, etc.). But the global bell-curve seems to be stuck in the 1980s.

By contrast, it is interesting to note that the global community of Toothless-Hillbillies (wonderful people, and perhaps "Toothless-Bogans" in Oz ) must have a great education process going, because their times have been dropping steadily, year after year, for the last 50+ years!
~~~~~~~~~~o0o~~~~~~~~~~

So, in the interests of some sort of global FSAE education process, I requote some of your above posts, with some added emphasis and brief comments.

From Kevin.

... I agree with your points about rear mass distribution. When we made the move in 2003 (UWA) to much more rear weight it was seen as the wrong path with just about every other team eschewing a 50-50 weight balance. In fact calcs support quite a lot more rear weight even with the same size tyres front and rear (60-65% with appropriate suspension changes).

Yes. With all equal-sized tyres and ~F35:R65 you simply carry most of your LLTD at the front, and lift the inner-front-wheel during cornering. This has the beneficial side-effect of allowing you to use an open-diff without spinning your inner-rear-tyre.
~o0o~

Changing relative tyres sizes [ie. bigger rears, smaller fronts] and you could go much further, making RWD the way to go, with a car able to do well IN ALL CIRCUMSTANCES.

(My ADDED emphasis.)

This is the way the vast majority of circuit racecars have done it for the last 50+ years. Some historical notes here.

Pre-WWII, racing was mainly about top-speeds (and reliability, as always). Cars would get up to top-speed and travel long distances on (quite rough) country roads. Then heavy braking as they entered a small village, four-wheel drift around the fountain in the middle of the town-square, then back up to top-speed to the next village. Roughly 50:50 weight and equal tyre sizes worked well here.

Immediately post-WWII there was less money, more amateurs in motorsport, and lots of now unused airstrips. So the new airstrip-racetracks were shorter, with many corners connected by short straights. Initially, with low-powered cars (like the Lotus 7) the 50:50 weight and equal tyres sizes still worked OK. But as power increased, and still with RWD-only, the rear tyres couldn't take it anymore!. They kept melting! So, the simple fix was bigger rear tyres and more rear weight!

By the time of turboed 1,000+ hp F1 cars, the rears were monstrous ~20" wide slicks, still with relatively small fronts. Similarly in Sportscar racing (see turboed 1500 hp Porsche 917, much earlier than the F1s). Weight distributions of ~F30:R70 were common. These cars could use all their horses to accelerate very hard, AND they could also go around corners fast.

With interweb+++, all this should be BLEEDING COMMON KNOWLEDGE (), and is why I get annoyed when FSAEers say "Oh, but we CAAAN'T be good at BOTH Acceleration AND AutoX...".

In the 1990s Max Mosely decided that for PURELY AESTHETIC REASONS he liked the equal-sized tyre look. So he MANDATED it in F1! (Well, almost equal sizes, with fronts very slightly smaller than rears). This had NOTHING to do with performance. In fact, the cars became notably slower accelerating off the start-line and out of slow speed corners, but nobody was allowed to mention that.

Much more interesting history here, but briefly F1 cars DO NOT have their tyre sizes based on performance. It is just the (BRAIN-DEAD ) Rules!
~o0o~

WE WANT THE ENGINE AND DRIVER AS CLOSE TOGETHER AND AS REARWARDS AS POSSIBLE. You would probably agree that this means not having double wishbones at the rear. It also probably means hanging the engine out the back 911 style. Achievable, but has some packaging considerations. The newest ECU car tries push the weight further rearwards than before, including a live rear end.

(My ADDED emphasis.)

Agreed on the first sentence. From a "big-picture" approach to car design, the overall size of the car comes first (ie. L/W/H, and WB), and the overall mass-distribution is a very close second (ie. CG height, F:R weight, and Yaw-inertia mainly).

But I think you could get those right even with Double-Wishbones. However, the suspension type is of very low importance, and DWs are the most complicated type there is, so they should be the last choice. Also I reckon the right F:R mass distribution can be achieved with engine inside the wheelbase (just squashed up a lot), which then gives a lower Yaw-MoI.
~o0o~

There are car configurations that make your assumptions work reasonably well, but they almost definitely involve powertrains currently unused in FSAE, as well as a vastly different car architecture. Not implementing these is not just a case of laziness...

Agreed that the standard powertrain layout needs changing, but I do not think it is a "vastly different car architecture". Just a simplified and squashed-up one. Like yours, but a bit more so!

It is in this area that I believe that the students are, by and large, really being lazy. It is the laziness of not wanting to break away from the rest of the flock.
So,
"Everyone else uses an off-the-shelf BIKE-ENGINE, which pushes the driver way too far forward, which then makes the rears light up with the slightest opening of the throttle. But we'll do that too, because doing anything else requires, err..., original thinking..."

There is a herd mentality that says that it is OK to spend ages designing and building a ridiculously complicated suspension system, and electronic-paddle-shifter, and carbonfibre-tub-and-everything-else, and other junk, but for some reason YOU MUST NEVER CHANGE THE POWERTRAIN LAYOUT! (Well, some do, but a tiny minority.)

Laziness? Stupidity? Whatever you call it, it is causing the performance of the cars to be stuck where they were 30 years ago. Namely, with the rear tyres on fire, while the car is all but stationary as it tries to accelerate hard out of a slow corner.
~o0o~

The pace of improvement in FSAE is slow, with high student turnover, poor knowledge retention, and conservative design being the primary cause. But ... We are heading towards the go-kart slowly but surely...
...
- Evolution is slow and fast...

Yes, and lots of other things I would like to add. But better stay on message.

IMPORTANT POINTS for students.
1. GET THE BIG THINGS RIGHT FIRST.
2. Until you do, DO NOT WASTE TIME ON TRIVIALITIES (eg. push/pullrods&rockers, electro-pneumatic-shifters, drive-by-wire, and really STUPID things like traction-control to stop your rear-wheels spinning, simply because you did not put enough weight on them!).
3. Re-read Kevin's post above. Several times.
4. Take a close look at ECUs car. A good evolutionary change. See if you can evolve it simpler and better. (Hint: I might tilt the cylinders back by ~45 degrees, and only have ONE of them (though still ~600cc).)
~~~~~o0o~~~~~

More following ... (10k char limit!).

Z

[Z]

From Dunk.

"Q1. Explain how the car's "power" and "grip" influence the Acceleration event..."

Based on my observations of wheel spin on launching I have to say that cars are low on grip in the early stages, so this is the limiting factor, not power. Further down the course the rate of acceleration is dropping so the engine is struggling to overcome the drag and inertia, i.e. it is lacking in power.

Yes, that is the gist of it. But I will wait a few more days before giving some numbers that show how grip-at-launch is significantly more important than maximum power later on. Meanwhile, if anyone else would like to take a crack at answering the questions...? (The F-5000 vs F-Ford issue is hinted at above.)
~o0o~

Bottom line, IMO, is that the current E-cars do NOT have a significant advantage over the C-cars. The classes DO NOT have to be split.

The main reason the E-cars benefit from 4WD is via better regenerative braking, which allows them to carry a lighter and less expen$$$ive battery pack. But the E-cars' current ~half-second advantage in Acceleration is merely a by-product of this. Their main advantage in Accel is that the C-cars have locked themselves into a very ineffective ~50:50 weight distribution, simply because they don't want to (or are too lazy to?) mess with the off-the-shelf powertrain layouts.

I note that quite a few of the C-cars in the recent FSUK were within 50 points of First Place outright, but they lost more than 50 points to the E-cars in the Acceleration event (Edit: See PS). So they were overall LOSERS!

Must try harder!

Z

(PS. Edit: FSUK results,
# Team O/A Acc.
1. Delft(E) 856 73
2. Stutt(C) 837 38
3. KIT(C) 828 37
4. Zurich(E) 827 75
5. Monash(C) 821 21
If better C-car Acceleration, then no E-cars on podium! )