1st revision of 2015 rules released

[apalrd]

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.

We had an identical conversation with a tech inspector at 2014 Michigan. We too were eventually found to be compliant, by the letter of the rules and the testing definition.

[apalrd]

I read over some other relevant competition rules regarding electronic throttle control. Here's the relevant ETC rules from Formula Hybrid (a US competition developed from the Formula SAE rules of the time, which has evolved separately over the last few years).

IC1.6.4 Electrical Accelerator Actuation
When electrical or electronic throttle actuation is used, the throttle actuation system must be of a fail-safe design to assure that any single failure in the mechanical or electrical components of the Accelerator actuation system will result in the engine returning to idle (IC engine) or having zero torque output (electric motor). See also: EV2.2.

Teams are strongly encouraged to use commercially available electrical Accelerator actuation systems.

The methodology used to ensure fail-safe operation must be included as a required appendix to the Design Report. See S4.2.1. A printed copy must be handed to inspectors at the beginning of Electrical Tech Inspection.

In fact, the length of the rules governing electronic throttle control are shorter (fewer lines) than the rules governing mechanical throttle controls, which are concerned with the cables jamming, or melting on the exhaust (which is not a concern with ETC throttles). I don't know enough more about Formula Hybrid to know of any team experiences with these rules.

Next, I bring the relevant rules from the SAE CSC (Clean Snowmobile Challenge):

4.2.6 Throttle Requirements
An adequate return spring on the throttle is required. The throttle must remain on the right side. The throttle will be operated with a direct mechanical operated thumb mechanism located on the handlebar to the rear of the machine (no twist grips). Fly-by-wire throttle systems are allowed.

The CSC rules also later specify a check of the throttle return spring during dynamic tech inspection (a process where a tech inspector rides the snowmobile on a small closed course to verify the vehicle response is acceptable for CSC, that it meets the minimum required speed, and that it shuts off as expected via the kill switch). In fact, Diesel snowmobiles are not required to run a throttle at all, and must simply retain the 'throttle' input from the driver. Several teams successfully have run ETC systems with great results, including the 2013 and 2014 competition winning teams. Several teams have also caught fire over the years, and there have been no ETC-safety issues ever (as long as I have been competing).

Next, I bring the Supermileage rules relevant:

B5.6.7 Throttle Control by Wire
B5.7.1 The engine throttle can be controlled electrically. Provided at least one (1) of the following conditions is met:
(1) The system will immediately return to a closed throttle condition if any part of the system fails.
(2)The kill switch circuit must leave the engine inoperable if any portion of the kill circuit fails. Thisincludes wire breakage and electrical short to chassis.

Again, they are letting teams determine their own safety and reliability strategy.

[mdavis]

We had an identical conversation with a tech inspector at 2014 Michigan. We too were eventually found to be compliant, by the letter of the rules and the testing definition.

That's what made it so much more fun. We had no issues with the same IA at MIS 2013. Tech in Lincoln 2013 was really stressful for us, when it really shouldn't have been. We got called on a lot of things that weren't out of the letter of the rule, but were rather judgement calls from the inspectors. The biggest was our seat belts, where because the spec on the belts didn't match the one in the rulebook, the inspector wasn't going to let us through, even after we showed him the spec in the rules that basically says "any belts that carry a given designation meet this standard". I'm sure I lost a few years off my life trying to call HMS, go find the tech inspector (who left the event, right after we got done in the tech bay the first time through), try to find the Chief tech inspector, call HMS back, lather, rinse, repeat. So when the IA was called into question (yet another thing where we met the letter of the rules, but apparently not the inspector's interpretation of things, or actually in this case, another individual at the competition, rather than our actual tech inspector), it was highly annoying and just added more unnecessary stress.

-Matt

[John_Burford]

Mcoach

The SCCA noise measurement approach has been tried in Formula SAE with very bad results.

John Burford

[Loz]

Clarity and ambiguity are out the window with the hugely subjective aerodynamic structural requirements rule.

The undefined, completely subjective and ambiguous components are in bold.

T9.7.1 All aerodynamic devices must be designed such that the mounting system provides adequate rigidity in the static condition and such that the aerodynamic devices do not oscillate or move excessively when the vehicle is moving. In Technical Inspection this will be checked by pushing on the aerodynamic devices in any direction and at any point.

Still no definition of what constitutes an aerodynamic device. Does this mean the rule applies to any external wetted surface?

It also includes a very vague stiffness requirement for "adequate rigidity" when static? "Adequate rigidity" is vague enough without it then having to be subjectively measured...

The undefined aerodynamic devices must not oscillate or move "excessively when the vehicle is moving". No clarity about what excessive movement is nor under what dynamic conditions it pertains to. Presumably measured again by eyeball.

They will check this by "pushing" on the undefined aerodynamic device in any direction at any point. Effectively they can push on any part of the vehicle wetted surface (structural or otherwise) and if they think it moves too much then you have problems.

Then it seems they seek to clarify the rule but do nothing of the sort.

T9.7.1 (continued) NOTE: The following should be seen as guidance as to how this rule will be applied but actual conformance will be up to technical inspectors at the respective competitions. The overall aim is to reduce the likelihood of wings detaching from cars whilst they are competing.

A rule that is vague, completely unclear and is measured by a subjective yardstick is written and stipulated to be "guidance" as to how the rule will be applied? It actually speaks very little about how the rule will be applied and certainly does not provide any guidance.

Then finally the slightest bit of an engineering requirement in the rule as note 1, yet it still remains ambiguous, subjective, unrepeatable and lacks any way of applying it consistently within a single competition let alone throughout all competitions.

T9.7.1 NOTE (continued)
1. If any deflection is significant, then a force of approximately 200N can be applied and the resulting deflection should not be more than 25mm and any permanent deflection less than 5mm.

One more use of a very subjective measure and another which in spite of them including a numerical figure (200N), is still only approximately defined. How do they intend on actually applying this approximate 200N load? A scrutineer with a well calibrated elbow?

It goes further to say that resulting deflection cant be more than 25 mm. Between which two points is this 25 mm being measured and how do they plan on actually measuring this movement of 25 mm in free space in any possible direction? Will they bring a CMM arm to each event? Presumably it will again be a subjective assessment.

If wings detaching themselves are such a big problem why not just mandate a tether line (of specified material) tying all wings back to the primary structure.

[kkung]

Generally the diagrams dont show the front wing restrictions particularly well, as the diagrams imply that nothing above 250mm is allowed in front of the front wheels, but the text contradicts this implying that once above the tyres in a frontal view a wing is legal.(The diagram T9.3.2 details that between 250-500 in front of the tyres is restricted, but the text T9.2.2 details that above 250 is un-restricted as long as the forward view of the tyres is unobstructed.) Why not just a blanket restriction on front wing height rather than all this complication?

Cal Simraceway(Berkeley), whats the OD of your 8" wheels out of interest? as this would likely make the front wing little restricted. Also DUT are potentially have little restrictions with their small front tyres?

Will read in more depth when I get home from work.

Westly.

The tires we used in 2013 were 15" OD, although we upsized to the 10" Hoosier LC0's in 2014.

[MCoach]

John,

Could you elaborate on why the implementation did not go as expected? Feedback and understanding as to why the rules have been structured and implemented are as well as any history attached gives significant insight to the teams.

[John_Burford]

Sound is cumulative. Depending on how close another car is to your car, you may violate the sound threshold. This also causes complication as to which car violated sound. After a few years of this approach, steady-state testing was adopted. Teams were very happy to go away from the SCCA approach. Also under the SCCA approach, many teams would not know they were violating sound until endurance.

John Burford

[MCoach]

I think if more leeway was given on sound for an event like accel, have the teams run accel with the microphone set up nearby and if they fail or get close (similar to the SCCA rules) then they are warned or told to fix it. Any runs that are made outside the sound threshold are either dropped or held hostage until a fix is made. I've had this work for a much more amateur and more rule breaking prone class where I held fast lap times for qualifying hostage until either an item was fixed or a penalty was accepted.

We don't have to wait until the endurance to test teams. There are plenty of opportunities to test beforehand. I'm open to much more discussion of the rules topics at hand.

Thank you.

[apalrd]

I found, for your viewing pleasure, the relevant US regulations governing electronic throttle control systems. Here is a link to NHTSA FMVSS 124 (NHTSA is National Highway Traffic Safety Administration, FMVSS is Federal Motor Vehicle Safety Standard). FNVSS 124 governs 'accelerator control systems': http://www.gpo.gov/fdsys/pkg/CFR-201...sec571-124.xml

The FMVSS requires two things:

-That there are two energy sources to return the throttle to an idle position. Normally, the first energy source is the throttle motor itself, and the second is the failsafe return spring. For mechanical throttle systems, two return springs are required.
-That the throttle return to idle position (which is allowed to vary based on temperature, emissions calibration, etc.) when the driver LIFTS THEIR FOOT FROM THE THROTTLE PEDAL, or there is a failure of the control system. There is no verbiage to indicate any dependency on the brake in this case, at all.

In fact, NHTSA discussed a 'brake-pedal override' feature to be added to FMVSS 124, following the toyota unintended acceleration scandals of a few years ago. If anyone feels like reading it, here's the link to the proposal: http://www.nhtsa.gov/staticfiles/rul...NPRM_Final.pdf (It's long, I suggest not reading it). Here are a few excerpts:

The BTO [Brake Throttle Override] system may check conditions such as vehicle speed, engine revolutions per minute (RPM), brake pedal travel, and pedal sequence (i.e., whether the brake was pressed first and then the gas pedal, or vice versa) to determine if the driver’s intention is to stop the vehicle. Based on these conditions, the BTO system may determine that the combined brake and gas pedal inputs are actually intentional

We believe there is no particular safety issue in these situations, and in fact this type of “two-footed” driving capability can be desirable and may be in widespread use.

The current language of the test procedure in FMVSS No. 124 is expressed in terms of the return of an observable moving part, i.e., the throttle plate, to a closed or nearly closed position. It does not prescribe other types of vehicle fail-safe responses besides throttle closure. This neglects the variety of ways in which powertrain output in a vehicle with a modern throttle control system can be reduced to an acceptably benign level, e.g., spark adjustment, even though the throttle plate may be at a non-idle position.

NHTSA does not believe the intent of the Standard should be construed as merely setting a limitation on throttle position. Instead, it is evident that the fundamental safety purpose of the Standard is to prevent a vehicle's powertrain from creating excessive driving force when there is no input to the accelerator pedal. There would be no safety reason whatsoever to require the throttle to close if that did not limit vehicle propulsion.

Even if it is well established that FMVSS 124 does apply to ETC systems, regulating ETC systems by drawing analogies to mechanical systems has undesirable outcomes.

Fuel injection and ignition timing are among factors that can be varied without any change in throttle position.

Modern engines routinely have variable valve lift and/or timing control. In at least one recent engine design, the level of valve control is great enough that the throttle plate no longer throttles the engine during at least part of the engine’s operating range. Instead, air intake is throttled to a large extent by the intake valves themselves while the throttle plate stays in an open position. In such a design, requiring "return of the throttle to the idle position" would be design restrictive without any safety justification.

Finally, here's a video of a rally driver (with a highly turbocharged engine) which clearly shows that he uses two pedals (in some cases, it appears three) at the same time. Additional airflow is required to build boost, and honoring a legitimate driver demand is not a safety issue. https://www.youtube.com/watch?v=wdy8CG09rSU