Three simple questions - pls point me

[lsrengineer]

Hello,

I'm new here.  A LSR team has asked me to do a few calculations.  I went to the Aug. 2011 speed week.
I have a few "simple" questions and was not able to pull up answers with the search function.

1 - the current car has a Goodyear Tire with the following markings :  21.0 x 5.0 - 15  and "5XZSM731" - I also see "D2111" on the tire.  What is the official model info. for this tire?  Is it still available, what is the speed rating?  How old is it?  Do I ask Tom Burkland?

2 - for the above tire what is the growth as a function of speed?

3 - what are the exact timing device locations that are used to produce the timing result numbers posted on the website and/or printed on the timing slip?   e.g. quarter mile ?  This is for the long course.  Appears to be the following results: quarter mile 1, mile 2, mile 3, exit speed, fastest speed.  Is there a diagram?  As far as I know the course is 6 miles long.  The first marker is "0" this is at the start, so "0" indicates the start of mile 1, right?  Sorry for the newbie type questions.


Thanks,
-Henry

[dw230]

Henry,

The answer to #3 is in the rulebook. If you are a consultant to an LSR team you should have one at your disposal. Were I to pay someone for his expertise I would want him to know the parameters.

DW

[lsrengineer]

Thank you DW.
I'm working on getting a copy, may have one by tomorrow.
-Henry

[jl222]

  lsrengineer.... 21/4 mile = 2I/4 from starting line

                      1 mile time = distance between the 2 mile and 3 mile

                      2 mile time = diatance between the 3 mile and 4 mile

                      3 mile time= distance between the 4 mile and 5 mile

                       exit speed is timed with a 132 ft timing trap just before the end of the last or 5th mile.

      This is for the long course, the short course must be different as they time the mile before the 21/4

      For some reason the results for 2 of the 222 car were put on the short course but we never ran on the short course. But then again some of our results were never pulblished

                          JL222

[Stan Back]

The "quarter mile" is the time between the 2-mile marker and 1/4 mile after it -- the first quarter mile of the (usually) first timed mile (between the 2-mile marker and the 3-mile marker) on a long course.

[George Fields]

Henry,
Gene Burkland and crew spun a Goodyear Frontrunner for me in '95 and I have the numbers in my book. The book is in Utah right now, but will have it at WF. If your are there, look me up.
George

[desotoman]

1 - the current car has a Goodyear Tire with the following markings :  21.0 x 5.0 - 15  and "5XZSM731" - I also see "D2111" on the tire.  What is the official model info. for this tire?  Is it still available, what is the speed rating?  How old is it?  Do I ask Tom Burkland?


Thanks,
-Henry

Are those the tires that were made for the "Racing Beat" Team many years ago?  Here is a link for you on what is available nowadays from Goodyear. Page 6 for standard Frontrunners, Page 8 for Eagle landspeed tires.
http://www.racegoodyear.com/tires/pdf/Drag_MSRP_MARCH.pdf

Tom G.

[Glen]

At the world finals there will be two courses both 5 miles long, now called combo courses to help speed up the runs. Won't know until next year how many courses there will be for speed week, depends on the salt.

[Stan Back]

Henry --

Here's the simple formula for gear selection used to set records.  Gotta know (or guess) a little.  What's the record?  What's the RPM of your peak horsepower?

Add 2 MPH to the record -- what gear do you need to do that at peak horsepower?
(Reasonable tire growth cancels reasonable slippage, go to Impound and have a beer with Dan.)

Stan

Here's the edit -- If you don't get there, you simply don't have enuf HP, and changing ratios won't help.  Damm, this is easy, maybe I should copyright this!

[lsrengineer]

 lsrengineer.... 21/4 mile = 2I/4 from starting line

                      1 mile time = distance between the 2 mile and 3 mile

                      2 mile time = diatance between the 3 mile and 4 mile

                      3 mile time= distance between the 4 mile and 5 mile

                       exit speed is timed with a 132 ft timing trap just before the end of the last or 5th mile.

      This is for the long course, the short course must be different as they time the mile before the 21/4

      For some reason the results for 2 of the 222 car were put on the short course but we never ran on the short course. But then again some of our results were never pulblished

                          JL222

Great thanks, this is pretty clear now.

[lsrengineer]

Henry --

Here's the simple formula for gear selection used to set records.  Gotta know (or guess) a little.  What's the record?  What's the RPM of your peak horsepower?

Add 2 MPH to the record -- what gear do you need to do that at peak horsepower?
(Reasonable tire growth cancels reasonable slippage, go to Impound and have a beer with Dan.)

Stan

Here's the edit -- If you don't get there, you simply don't have enuf HP, and changing ratios won't help.  Damm, this is easy, maybe I should copyright this!

well, OK sounds reasonable, thanks

[jacksoni]

Henry --

Here's the simple formula for gear selection used to set records.  Gotta know (or guess) a little.  What's the record?  What's the RPM of your peak horsepower?

Add 2 MPH to the record -- what gear do you need to do that at peak horsepower?
(Reasonable tire growth cancels reasonable slippage, go to Impound and have a beer with Dan.)

Stan

Here's the edit -- If you don't get there, you simply don't have enuf HP, and changing ratios won't help.  Damm, this is easy, maybe I should copyright this!

This year was expecting, as everyone does, to go to impound. Not to be. Tire changes to try get into HP peak range resulted in going through traps more or less at 8000, 8400 and 9000 rpms.  Same speed. Like Stan said: If you don't get there, you simply don't have enuf HP, and changing ratios won't help. Back to drawing board!.

[lsrengineer]

Thanks for replies re. gearing.  I'm trying to get my head around it and if possible simulate to show that you'all are correct.
I've heard the same thing from multiple sources.  I assume that a different gear will cause a different top speed, at least in some cases, but maybe not enough to matter if the gearing is close already.  I'm thinking if you are going through the last mile and under the HP rpm peak, you would try more ratio.  I don't want to beat this to death, I don't know enough compared to all the others here doing this for years.  I'm working on a program that calculates the average tractive and drag forces every meter to see if that shows something, I'll be able to change the gearing with one entry and see the top speed and where the top speed happens.  Probably this has been done a thousand times by people here.  I have a tendency to attempt simulation of reality.

[hotrod]

You have two issues to consider.

For a give speed X you have some hp Y that you must deliver to the ground to over come both aero drag and rolling resistance. If you cannot get that much power to the ground you can't get to X speed.

But what some people miss is on piston engines you also have to deal with the shape of the torque curve and gearing. It is possible to have an engine that generated the required hp to deliver Y hp to the ground including parasitic losses in the transmission, differential and wheel bearings etc, but still not be able to reach your design speed because of your choice of gearing. If the gap between gears is wrong you can have a situation where you can pull up to red line in your next to last gear but when you shift to your top gear you drop to a part of the torque/hp curve that the engine no longer produces enough power to pull back into the peak power point on the power curve.

On page 2 of this thread I have a simple basic program I wrote that figures some of the hp and weight values.

http://www.landracing.com/forum/index.php/topic,7775.15.html

There are other programs out there such as gear split that also provide some of the info you are looking for.

If you can gear the car so it always has surplus power to the wheels for the speed it is going you can avoid the problem of falling out of the power curve on the last shift. Since power required for a speed increases at the cube of the speed, the last gear split needs to be very close in ratios to allow the engine to pull back into the power peak after the shift.

Larry

[lsrengineer]

Larry,
I have the engine torque curve in the calculation along with the estimated drag curve.  Each 1 meter gets a number of iterations because you don't know the exiting speed of a given meter and thus don't know the average acceleration.   With some trouble I'll be able to show what happens in each gear and then piece the results together at the shift points. Will be interesting to see what happens with a final drive change.   I'll take a look at your link.
Thanks,
-Henry