Technical Analysis for September 17, 2017 event at YYC

[MurrayPeterson]

Or maybe it's the Line choice discussion that would be quicker to move haha

I want to get back to the line choice debate/discussion.  I like Quentin's latest diagrams, although I want to see the "real" finish line marked on them.

The choice between Quentin's line and Ryan's line is interesting for a finish line that is very close.  Does backsiding work best when the acceleration zone is small, or does shortest line win?  And how much distance for acceleration count in this situation?  How much line difference is dependant on thrust?

This one seems to deserve it's own test and tune.  With data collection and analysis in addition to just the clock.

[Myz]

OK, gentlemen, the lines are drawn!  Shall we set up the time and place of the duel? 

How much tire do you have left, Terry?

How about October 1 at the YYC event at the conclusion of the day after all the official runs are done.

Rules:  Each driver will get 3 runs with watering of tires etc. provided for to ensure consistent tire temps and no overheating.  Other rules such cones counting etc. will be the same.

I suggest Terry goes first since he is the most used to the car on cold tires etc. and would be disadvantaged the least and we will draw lots or flip coins for the rest of the run order.

Winner will be based on normal solo rules with the best/fastest run including cone penalties, DNF's etc. counting.

Participants (let me know who is in):   Terry, Murray, Ryan, Stephen, Cam - any others?

We can compensate Terry for tire wear, gasoline upon agreement etc.

Sound good? 

Any further suggestions?

 

Wow,
I learned so much from reading this thread but moreso, its exciting to see friendly "call outs" or grudge match styled racing coming to AutoX.
Thats usually reserved for the drag scene.

I'm expected to be up north on that Oct1 weekend but I'm thinking I need to feed the wife an excuse so I can be present to watch this battle

[Sprockett]

Sorry Reijo, I have no idea what Terry is even arguing? I suspect he doesn't either. Maybe you can translate?

In the post you quote above he is suggesting it's crazy Tom (in an SSP Vette on Hoosiers) raw timed Murray (in a CS Miata on street tires) by 4 seconds (actually ONLY by ~2sec per course) and offers that as evidence that PAX doesn't work. All the while ignoring the fact that Murray beat Tom on index. All this of course on a course that he contends is a Power course.

I don't think Terry knows what PAX is and what it is used for. His car is the wrong choice for CS and it is questionably prepared if at all. I don't see anyone arguing that any driver should be able to jump in it and come anywhere close to Tom Gs raw times on any day on any course...except Terry...confusingly enough.

[JCS]

Here's my video with telemtry. 

https://www.youtube.com/watch?v=-qxgoO7OTIU

I'm interested to know if higher powered cars were significantly faster than the corolla through the kink, I look to be at around 73kph before lifting.  I'm a ultra low powered car (~100hp atw new 26 years ago).

I take Line A.  I do think I have a video of taking line B.  I will try and get a side by side to see what difference there is tongiht.  Fastest time in afternoon was a 39.6

[PedalFaster]

I am more than happy to let any of our quickest drivers in high powered car, Cam, Ryan, Tom, Stephen borrow my car and see if they can beat or equal their own time in a low powered car.

Who'd like to take the challenge???

OK, gentlemen, the lines are drawn!  Shall we set up the time and place of the duel? 

Participants (let me know who is in):   Terry, Murray, Ryan, Stephen, Cam - any others?

I am 100% in, and would be happy to contribute to expenses.

[MurrayPeterson]

Sure, I'll buy into this challenge.  Win or lose, sounds like a *lot* of fun.

[Bitters]

I only recorded data in the morning, here are 4 of my laps over those sections.

https://drive.google.com/open?id=1jdxYCshW0ZdMM-p8K1kD-Wrvuq16ejJ4Yw

https://drive.google.com/open?id=1kmOK5rpZzJ86b6B2HTkCVjL5cX4TWI99UQ

https://drive.google.com/open?id=14qmfEc-DMLK3WkfP-r6rh75W2RvDQH_VnQ

Between the three images, you can see my car speed at various points, and the time delta for the lines. Unfortunately it looks like lap 2 was perhaps just driven better (third image), since I had lots of speed mid corner despite the tighter line.

[Bitters]

Same data output but for Tom Kerns:

https://drive.google.com/open?id=1RPFMdwQQ1AZIq7NtP8WruAC2swPD84vvCg

https://drive.google.com/open?id=1WFQKSlNRP3etYE-b671DXKLwxhkNmGxxnw

https://drive.google.com/open?id=1ZkIZkzY2Jx7tPi5O2B0FMVN-JVU7AWekFg

[Reijo]

Sorry Reijo, I have no idea what Terry is even arguing? I suspect he doesn't either. Maybe you can translate?

In the post you quote above he is suggesting it's crazy Tom (in an SSP Vette on Hoosiers) raw timed Murray (in a CS Miata on street tires) by 4 seconds (actually ONLY by ~2sec per course) and offers that as evidence that PAX doesn't work. All the while ignoring the fact that Murray beat Tom on index. All this of course on a course that he contends is a Power course.

I don't think Terry knows what PAX is and what it is used for. His car is the wrong choice for CS and it is questionably prepared if at all. I don't see anyone arguing that any driver should be able to jump in it and come anywhere close to Tom Gs raw times on any day on any course...except Terry...confusingly enough.

Ryan, I agree with that there are some mistaken notions about what PAX (Professional Autocross Index - by Rick Ruth) is. 

So let's rehash what it is:

But, first adding a bit of humour to this (a video Rick Ruth put on YouTube):

https://www.youtube.com/watch?v=uouXAYx--fI

So what is PAX/RTP (Racer's Theoretical Performance)?

1.  It is not an official SCCA standard.  Although I noticed this year for the first time they included PAX times for National level events.  In the past they did not post PAX results.

2.  There is a separate PAX set of numbers for Pro Solo.  They are not the same.  I believe Howard Duncan may be taking care of the Pro Solo PAX if I am not mistaken.  Correct me if I'm wrong.
3.  The PAX/RTP numbers are generated by Rick Ruth.  Yep, one person looks after this on his own volition.  He studies results from National-level events and also some other ones from some bigger and key regions (e.g. CalClub/LA is one of them).

Here's a listing of the events that Rick uses to do his calculations (I think he omits some of them if it, say, rains):

http://solotime.info/pax/rtp2017.html

So how do you explain these PAX/RTP numbers? 

Well, obviously Rick compares the relative times of competitors from major events and then calculates an approximate index number so that you can compare times between classes.  A-Mod, being the fastest class, is assigned a value of 1.0.   The rest of the classes go down from there.

Interestingly enough when Joe Cheng and Gary Milligan (both are from the Vancouver, BC area) re-wrote the book a couple of times on how you build an A-Mod and decimate the competition, PAX values went down for everyone across the board.  Same thing happens on a smaller scale for a class such as when someone builds a new ringer car for any class including stock classes (e.g. the new MX-5/Miata is doing this now).

So what does all this mean? 

Well, generally, SCCA National level events are held to a particular standard for course design, the way the events are held and even the lots where they are run.  Often they are run on huge lots and they aim for mostly flowing courses, lined, marked out well etc. (see Roger Johnson's Course Design Manual) and there are often 250 or more competitors.  They are held at huge venues like major sports arenas, race tracks and airports (often military). 

There is some variance due to the surface and venue - age, concrete or asphalt, elevation, weather etc.  I know Rick tends to ignore wet results for the most part.  I don't know if he accounts for elevation and temperature etc..  And, of course, he also follows people and who are at the top of the rankings for the most part because they tend to have fully or nearly fully prepared car and drive them well.

Rick observes the results from every year and if it appears that some class has sped up all of a sudden due to a new car that has not been re-classified, he may or may not adjust the PAX for that class or might wait a year to confirm it.  That is often caused by some new technology (e.g. 275-35-15 Hoosiers) or some new car that is substantially faster than the last generation of competitive cars.

It is an immense task that Rick has taken on and by no means the end-all and be-all of comparing results.  It is not perfect.  It can never be perfect.  But it is the best that we have.

If a region is really far north (let's say Edmonton), with cold weather, a small venue on asphalt, small tight course designs (not saying that is what they are running ... this is just an example), and very few cars that are fully prepared to the letter of the rules.  Will the PAX appear fair or consistent for them?  More than likely not, although in some cases by sheer fluke they may.

So in the end there are a lot of factors that figure in and if you really want to know where you stand, prepare your car and yourself (especially), and go south and compete at a big Tour or even the SCCA Nationals and find out where you "really" stand.   

Well, I could write a book on this topic, but there is no time for that right now on this one thread on our forum.  Hopefully this gives everyone a bit more understanding into what PAX is.  In the end it can be a useful tool to compare yourself with others locally but take the results with a grain of salt and realize that the original parameters may not entirely reflect ours.  We do try and set up National-style courses and methods of operating as much as possible and often even copy elements from Tours/Nationals etc. if we can.  Our best lot right now if YYC obviously and even it is a bit on the small side for a SCCA National style event as many of us know but it is not bad.

Hopefully my rambling on this note is not too confusing and makes sense.  Take a look at the site mentioned above for more information.  Just for fun, I noticed the 2007 Nationals from Heartland Park were also listed there and I placed 6th in PAX at the event in Bill's CSP Miata.  Not bad. 

[Reijo]

Here's some really good and more background info on PAX/RTP (incidentally, maybe we should be rightfully calling it the RTP index!) almost directly from Rick Ruth and presented by our friends just south of us in Great Falls:

http://www.greatfallsracing.com/phpBB3/viewtopic.php?f=20&t=2310

R

[MurrayPeterson]

Also, keep in mind that Rick Ruth can assign PAX values "out of the blue", with aerguments that don't ring right to me.  And of course, there are the new cars to a class (2016 Miata), where he has to make some sort of a wild-assed guess.  Next year, one hopes the PAX will align with the other classed.

However, I must note that I came in 32th overall PAX at Packwood this year, and that aligns with my belief about how well I drove.  Cam PAXed 16th, and Ryan 21st.  So, probably no (relative) change to PAX values for CS this year.  Basically, I need to drive very, very close to the same scratch times as BS cars (Hi Ryan!).

[Terry Johns]

My suggestion is after the event is over, we get the top 2 guys in PAX, (probably Ryan or Cam) and let them do their thing in my car. If they equal their PAX time in my car I will retract my statements and admit defeat. I will choose the event just in case the top 2 PAX winners are sand bagging.

The issue for me is about course design, HP & PAX not creating a level playing field.

Who wants to play

[Reijo]

Also, keep in mind that Rick Ruth can assign PAX values "out of the blue", with aerguments that don't ring right to me.  And of course, there are the new cars to a class (2016 Miata), where he has to make some sort of a wild-assed guess.  Next year, one hopes the PAX will align with the other classed.

However, I must note that I came in 32th overall PAX at Packwood this year, and that aligns with my belief about how well I drove.  Cam PAXed 16th, and Ryan 21st.  So, probably no (relative) change to PAX values for CS this year.  Basically, I need to drive very, very close to the same scratch times as BS cars (Hi Ryan!).

And if we think of it from Rick's perspective, what choice does he have.  A new popular car comes along like the new MX-5/Miata and people "have" to know what the PAX nos. are.  A WAG is the only way.

Another thing to note here is that the SCCA affects the whole picture as well via classification of cars.  Some times an overdog car ends up in a class and changes it entirely .... as well as the RTP.

So there is a lot to this.   

[PedalFaster]

My suggestion is after the event is over, we get the top 2 guys in PAX, (probably Ryan or Cam) and let them do their thing in my car. If they equal their PAX time in my car I will retract my statements and admit defeat. I will choose the event just in case the top 2 PAX winners are sand bagging.

The issue for me is about course design, HP & PAX not creating a level playing field.

That experiment's doomed to fail, because if PAX works correctly, Ryan and Cam won't be able to match their PAX times in your car.

Why? Because Ryan and Cam are each driving fully prepped, class-leading cars. Conversely, you're in the wrong car (you're in an NC Miata, but the class-leading car in CS is the ND Miata, so the PAX is based on it), the wrong model car (you've got a PRHT Miata, and the PRHT mechanism adds about 75 lbs. to the car, all up high), and your car's not fully prepped (a full prep NC would have fancy shocks, lightweight wheels, a lightweight exhaust). I'd expect these factors to result in times very roughly 0.5-1.0 seconds slower than those of a fully prepped CS ND Miata.

Furthermore, no one, not even Ryan and Cam, can jump into a strange car and immediately drive it to its full potential.

*Furthermore*, no one's saying that we don't sometimes have power-intensive courses. We're just disagreeing with your contention that *all* courses are power-intensive courses. If you cherry-pick a power-intensive course, that will defeat the purpose.

You've basically designed a "test" that's impossible for you to fail. I don't know what that would prove.

[Reijo]

My suggestion is after the event is over, we get the top 2 guys in PAX, (probably Ryan or Cam) and let them do their thing in my car. If they equal their PAX time in my car I will retract my statements and admit defeat. I will choose the event just in case the top 2 PAX winners are sand bagging.

The issue for me is about course design, HP & PAX not creating a level playing field.

Who wants to play

That is a good idea.

However, also note that any two cars are not necessarily equal wrt PAX.  Some cars are "more equal" shall we say?

For instance, Cam's Corvette is a PAX monster (if that is appropriate to say).  It is capable of winning BS at the SCCA Nationals.  So I would already venture to guess that his time in your car (which is no longer the car to have in CS) would be slower in PAX.....as might be expected.

So, how about you take Cam's Corvette for a run in the contest?  (provided that is ok, Cam?).

Hmmm.....maybe we can swap a few cars/drivers and see what happens?  Murray?  Stephen (don't know what you are driving but ...)

I think this would give a fairer comparison all around.  Everyone would also have seen the course the same number of times then.

And, I'll admit, I have an ulterior motive.      hehehehe

I want to compare drivers.      PAX can get affected by aliens.   Let's see if there are some among us!