1st revision of 2015 rules released

Westly, the "general" rules has a restriction above 500mm, making the region above the tyre, but bellow 500mm allowed IMO.

Anyway, for constructive review / editing.....

T3.5.5 the angle of bend braces at less than 45 deg to the tubes bend plane will make the VERY common bent upper side impact tube solution illegal, or at least very wide. Is that the intention? Would it not make more sense to brace a bend perpendicular to the plane of the bend to support rotation of the tube about it's ends?

T6.5.9 Rack attached to frame - Some designs specifically feature unsprung mounted steering gear (ie beam axles). Is the intention here to ban such concepts? Or simply to ensure attachments are suitably strong/rigid?

I.C.1.7.1 Restrictor, supercharger, throttle ONLY - I understand the reasons for this change for the turbo designs, but with bypass/recirculation valves etc banned, this now creates a big issue for any positive displacement supercharger, which are quite happy to operate in partial vacuum. Would a propriety internal relief or bypass valve be considered illegal?

I.C.4.6 IC max voltage. This (60VDC/25VAC) is well below what is seen in the typical motorcycle charging system. Is the intention these systems are no longer permitted and on board charging deleted, or are to modified to comply?

Pete

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Originally Posted by Pete Marsh

Westly, the "general" rules has a restriction above 500mm, making the region above the tyre, but bellow 500mm allowed IMO.

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My reading of T9.4.2 was it only applyes between front the front and rear axles? The diagrams also show no height restriction on the front wing.

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Originally Posted by Pete Marsh

T3.5.5 the angle of bend braces at less than 45 deg to the tubes bend plane will make the VERY common bent upper side impact tube solution illegal, or at least very wide. Is that the intention? Would it not make more sense to brace a bend perpendicular to the plane of the bend to support rotation of the tube about it's ends?

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This sounds like it will affect many teams. My reading of this makes our chassis non-compliant unfortunately with a bent supported upper bar.

I agree with Andrew that rules are overly restrictive in relation to their implementation of ETC. In fact, when he brought that 10% note everywhere to me I knew exactly what it was referencing and think that it is completely unfounded to apply it to FSAE. For those who weren't aware of the blown diffuser era of F1, off throttle maps became a huge thing. The cars basically only closed the throttle on idle and purely controlled torque based off spark and fuel after that. Crazy aero ideas is why it was restricted there, not safety.

http://scarbsf1.com/blog1/2011/05/19...e-engine-maps/

But they sounded awesome:
http://www.youtube.com/watch?v=BmGgvHflXgc

This isn't really relevant to FSAE and restrict us from doing more creative things with the power unit. The rules regarding the ETC plausibility seem more like something that would be required for competition just on ETC safety. If a mechanical throttle sticks open, that's cool just hit the kill switch and no one bats an eye. ETC is put on the car and it becomes restricted to the point that it operates almost exactly like a mechanical throttle with all the electrical wizz-bangs to make sure of it and kill the car if it ever recieves some proper massaging in that one special way....That's no fun. Snowmobile SAE rules are a fair implementation of ETC, I'd reference those.

It looks like the monocoque rules basically want you to build a whole two assemblies if you want to bring one to competition. Much more testing needs to be shown for all composite panels...watch out, they will make you crash test the whole car next and be subjected to the NVH subjective noise test. Maybe install some nicer carpets ;)

IC3.3 Maximum Sound Level
At idle the maximum permitted sound level is 100 dBC, fast weighting. At all other speeds the
maximum permitted sound level is 110 dBC, fast weighting.

Holy crap...let me go pull the muffers off all of my car. Someone must think we should be racing road sedans around these tracks. I think passing 110dBA was equivalent to 120dBC for us at competition and we were well over 114dBA at idle in some instances...

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Originally Posted by MCoach

Much more testing needs to be shown for all composite panels...

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This is not necesarilly bad...there are quite a few teams out there eager to build a monocoque but some times their choices are poor. Think about it, you cannot really fail on designing a spaceframe safetywise, the rules mandate a really large portion of the chassis anyway. Also the smaller WT allowed if tested are more than welcome.

I think we all agree that wording on the new aero rules is poor; too many words, schematics that contradict the wording and so on. But it is not only that. I did a quick readthrough, and here's an example:

"EV8.2.2 Accumulators must be removed from the car for charging..."
"EV8.3.7 ...In the case that the accumulator is charged outside of the vehicle..."

You kidding me? You just told me that accumulators MUST be charged outside of the car! Seriously, does anyone read the whole thing through before publishing?

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Originally Posted by Pete Marsh

I.C.1.7.1 Restrictor, supercharger, throttle ONLY - I understand the reasons for this change for the turbo designs, but with bypass/recirculation valves etc banned, this now creates a big issue for any positive displacement supercharger, which are quite happy to operate in partial vacuum. Would a propriety internal relief or bypass valve be considered illegal?

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Some turbochargers (including the Garrett MGT1238Z which we acquired through the 'FSAE' sponsorship for our CSC clean snowmobile team) include an integral boss for a recirculation valve (Which is plastic).

A quick google image search found this picture of the turbo: http://www.turbosbytm.com/sites/defa...?itok=FrM5YHLd The recircultion valve mounts to the hole next to the compressor inlet. Within that hole, the 'inner' port goes to the compressor outlet, and is surrounded by a port which connects to the compressor inlet. The recirculation valve moves in this space to recirculate. It's quite integral to the turbo, but the valve is removable as there are several designs (I have a pneumatic and direct-electrical pneumatically piloted one).

While a recirculation valve isn't as important to turbochargers, the question still comes up for integral recirculation valves. As they don't vent to atmosphere, and bypass the restrictor, is there anything wrong with integral recirc valves?

I agree as well, that for a positive displacement supercharger, throttle upstream of the supercharger is a requirement to keep power down without a bypass valve. Even with a bypass valve, most superchargers run a throttle before the supercharger

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Originally Posted by Pete Marsh

I.C.4.6 IC max voltage. This (60VDC/25VAC) is well below what is seen in the typical motorcycle charging system. Is the intention these systems are no longer permitted and on board charging deleted, or are to modified to comply?

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This needs to be addressed by the rules committee. Would anyone like to submit a question for their evaluation?

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Originally Posted by MCoach

IC3.3 Maximum Sound Level
At idle the maximum permitted sound level is 100 dBC, fast weighting. At all other speeds the
maximum permitted sound level is 110 dBC, fast weighting.

Holy crap...let me go pull the muffers off all of my car. Someone must think we should be racing road sedans around these tracks. I think passing 110dBA was equivalent to 120dBC for us at competition and we were well over 114dBA at idle in some instances...

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Yes, we measured 116 dBA at idle at Michigan last year, due to the troubles we had balancing a high flow engine that wanted to rev high and a centrifugal clutch that required we keep the revs low at idle (we were sitting on the lean misfire limit, the noise was mostly due to popping).

We will likely need to at least double our muffler weight to comply with the new noise rules. This is an extremely unfair limit, especially to single-cylinder teams.

Mike, would you like to noise-test my car at warm up/light off idle and see if it passes the 100 dBC test?

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Originally Posted by apalrd

would you like to noise-test my car at warm up/light off idle and see if it passes the 100 dBC test?

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I used my team's sound level meter (the same meter we use to test our FSAE car for noise test) on my completely stock 2013 Fiat 500 Abarth and found that, already warm, the car hits 100 dBC fast weighting on the start flare, then drops to between 92 and 96 dBC depending on light-off (it cycles in a torque reserve for catalyst light off even at fully warm idle). This is at roughly 850 rpm.

If the engine was cold and stayed at the elevated idle for warmup and light off, it would have likely failed the FSAE idle sound test, at 1500rpm. Our FSAE car idles at 2600RPM, I don't know how we can be expected to be better than an OEM street muffler design on a racing car.

MCoach and I then tested his Sentra, with a modified header on a stock exhaust, he too failed the FSAE sound test, peaking the meter at 106+ dBC (for the 100 dBC range setting) at the start flare then decaying to 98 dBC at warm idle (800-900 rpm as well).

Edit:
We later tested both cars according to the noise standard (based on mean piston speed). The Abarth quieted down after it stopped retarding spark for catalyst light-off and passed the FSAE standard test at 5500rpm, but the Sentra failed (at 4500rpm) with a reading of 111 dBC.

After letting both cars sit for 4 hours, we tested again on, on elevated warmup idle. The Abarth failed with a 102 dBC elevated idle (~1500rpm) before settling down to the previously seen ~94 dBC normal idle. The Sentra failed the idle test when warm, at 106 dBC (at ~1100rpm) before settling down as well.

I'm honestly not sure how race cars are expected to be quieter than OEM production cars.

I spent some time watching the dBC readings at Lincoln in 2013 and walked away thinking that something around 115 dBC would be appropriate to force the offending single-cylinder cars with lots of low-frequency content to address their problems while allowing the rest of the cars to carry on without incredible difficulty passing the noise test. Even 4-cylinder cars are going to have trouble passing at 110 dBC without rethinking their silencing for 2015. This is a big jump and some justification for the rule change would be nice.

Regarding the electronic throttle rules, it seems that the new rules strip away most of the advantages of running an electronic throttle.

"IC1.11.2 The electronic throttle must be automatically closed when power is removed from it."
"IC1.12.6 Each TPS must have a separate detachable connector that enables a check of these functions by unplugging it during Technical Inspection."
-Means no reliable, unmodified, off-the-shelf Bosch throttles allowed because they must be driven closed beyond the partially open limp-home position and have a common power supply for the two TPS signals.

APP rules likewise make it difficult to use a reliable, unmodified, off-the-shelf component like the pedal from the Polaris Ranger 900 XP.

These issues are minor, however, compared to the above-mentioned fundamental issue with the proposed electronic throttle control rules. If you cannot decouple throttle position from APP for engine control purposes, what's the point? I thought the point might be to use off-the-shelf components instead of custom components and a throttle cable, but that advantage is gone too.

May I suggest a really relevant noise test style? If we're building a "weekend autocross car" why don't we build to the SCCA noise limits since someone in the rules committee is feeling so inclined to change them.

http://www.scca.com:8090/documents/S...asurements.pdf

A couple things seem to have been cleaned up, and I'm pretty sure I found a rule or two written about because of our team..

However, overall I'm still bothered by how unclear and random many of the rules are. Pretty ridiculous for a competition of this magnitude.

I'm glad I'm not the only one upset about the new noise rules. I hope all of the single cylinder teams are using their time to design mufflers now, rather than getting the rest of the car done. OTS components will no longer pass noise without 2 mufflers in the system, so that will be fun. As MCoach suggested here, and I have suggested to FSAE individuals, the SCCA noise test makes so much more sense that it isn't funny. And yet, here we sit. Apparently FSAE rules committee cares more about "design challenges" than they do about the hearing of the on-track workers. If they cared about a certain situation, then they should test in that situation. Yet again, we see logic seems to have escaped the rules committee.

I still see no definition of "off-axis" impacts for IA's. This is something we got called out for at Lincoln 2013. I had a nice discussion with Mr. John Burford about this in the tech bay. He claimed that any off-axis impact would break our IA off and that we needed to add straps to retain the IA. I pointed out to him that while he may be right, there was no specified magnitude or direction of the off-axis impact that the IA needed to withstand in the rulebook, and therefore we were within the letter of the rules, and we didn't need to add the straps. I told him that if he wanted to call out teams on the off-axis loading condition, that there needed to be a standard test that was performed at the same time as other IA tests to prove that the IA was capable of handling such loading conditions. Apparently that conversation was forgotten when we rolled out of the tech area, or other things like header wrap and the noise levels of teams playing by the rules were deemed more important.

-Matt