The Santa Monica Sports Car Club has continued the FFN for many years, and you are always guaranteed a great time!

Tonight was different in that my car was not ready to run Class A with a computer and Joe’s car had my old Alpha Elite in it and no reader board.  A few days earlier Joe had asked me to rig up a reader board on a Ram Mount so we could mount it to his windshield with a suction cup. Well by the time Friday night came about, a large stone had severely cracked the windshield in Joe’s WRX. So we opted for a clipboard instead. (The best decision of the whole rally)

What this did, was force Joe and I to communicate better. It allowed me to concentrate more on driving and being on time, and Joe more on the instructions and traps. I really think this system works better.  As long as I knew what the next instruction was, that is what I was concentrating on, and not a few steps ahead. Sometimes when you are thinking a few steps ahead in a TSD trap rally, you zone out on the current tasks/traps.  By doing this, we went through the entire rally and properly executed each instruction and did not fall for any of the traps.  This is always  a difficult task when Jeanne English is the rally master.

A quick note for Jeanne and the SMSCC gang. Great Rally!!  You guys put on a great event. The roads on this rally where in the mountains outside of Santa Clarita California. Great roads for some spirited driving!

After catching each of the traps, which not only tested confidence, but knowledge of the rules, Joe and I managed to score an eleven. Meaning we were eleven hundredths of a minute off for the entire 2+ hour rally. Not perfect, but good enough to pull a 1st place win in Class A. It had been a while since Joe and I had run together and won. It was a good feeling!

The other nice part about this rally, was the attendance! There were 20 cars/teams running this rally. I hope this is a sign that the economy is turning around and people are starting to get out and enjoy themselves more! It sure was nice to see new and familiar faces at this event.

So if you are in the Los Angeles area on the 1st Friday of the month, bring a friend, a car and a watch to the corner of Devonshire and Sepulveda in Mission Hills, where behind the BofA you will find die hard and newbie rally enthusiasts gathering to enjoy their Friday night without the TV, without the bars, but with good friends and awesome roads.

Don’t be shy either, if you have never done something like this before, they have a beginners meeting to tell you how to do it before the event starts.

I wanted to add to Joe’s message regarding Midnight Run. I helped with checkout last weekend (so I’ve been on the course) and I highly recommend running this rally. I enjoyed the roads, the vistas, and the (for the most part) utter lack of civilization. It is amazing that only a couple of hours from the California coast is wide open farm land for miles and miles. We did the checkout during the day but I continually envisioned how the roads would be at night time.

It is definitely a straightforward rally, not too easy, but not so overchallenging or complex. Not that I would ever advocate breaking laws or driving unsafely, but you will be on some straight roads, in the middle of the night… very scarce law enforcement, cyclists, kids and dogs all sound asleep, not wandering into your path. And as Joe said, the overnight rally is fun, it is not boring, it goes by faster than you think it will. Just sleep late on Saturday and bring coffee or energy drinks for the road. Snack lightly as you go and don’t eat a huge meal at the break. Swap drivers occasionally if necessary. Studies have shown that 4 a.m. is the slowest point in the human body’s rhythm so make sure that you are talking and playing the radio etc. Once the sun comes up you definitely get a second wind. Bring a handheld lamp to view routes and maps without having to use the dome lamp. This is the way almost all rallys used to be run, the daytime rally was the exception to the rule. So come out and do the Midnight Run and have a great time!

Kaylee
Silver 1995 Trans-Am 5.7 6-speed
rallying since 1985

Technorati Tags: midnight run road rally, Road Rally

An SCCA Regional Time-Speed-Distance rally written by Rachel Smith. The second in
the SMSCC Rally Series of 2009. This rally will be a fun romp and lightly trapped.
Come out and enjoy the scenery of Ventura County and the surrounding environment.
See the sights and the scenery. Beginners welcome.
Start Time: 10:00
Date: 2009-05-02
End Time: 16:30

Technorati Tags: Autombile Rally, automobile rally, Car Rally, car rallye, FFN, First Friday niter, Fun things to do with your car, fun with cars, Fun with your car, Los Angeles Road Rally, rallies, rally with your car, road rallies, Santa Monica Sports Car Club, SMSCC, Southern California Rally, Southern California Road Rally, TSD, TSD Rally

Read the FFN flyer and General Instructions at www.smscc.org or www.calclub.com/roadrally.htm.  You can also see pictures from previous FFNs and our other events in the Photo Gallery section of the Cal Club road rally website.

Specials:
Zero Dollars:  Contestants are awarded ‘Rally Bucks’ for getting zeroes – Class A gets 1 Rally Buck per zero, Classes B and C get 2 Rally Bucks per zero, and Class D gets 3 Rally Bucks per zero.  Rally Bucks can be accumulated and used like cash for FFN entry fees.

Both driver and navigator must be SCCA members (for both the FFN and Inaugural).  If you are not, you can buy a weekend SCCA membership for $5 per car.  (Passengers do not have to be SCCA members.)  Please contact us if you have any questions about this.

Minors:  For a minor to participate, both parents must sign the SCCA Minor Waiver.  Each parent’s signature is only valid if the parent signs in the presence of the rally registrar or the parent’s signature is notarized.  You can download the SCCA Minor Waiver from:

http://www.scca.com/documents/insurance/SCCAminorwaiver.pdf

Info:  Larry – Larry_Scholnick@yahoo.com  310-270-8826
Jeanne – ean21@juno.com  310-372-7168

Technorati Tags: Autombile Rally, automobile rally, Car Rally, car rallye, FFN, First Friday niter, Fun things to do with your car, Fun with your car, Los Angeles Road Rally, Rally event, rally with your car, Road Rally Forum, Santa Monica Sports Car Club, SMSCC, Southern California Road Rally, TSD, TSD Rally

The VictoRacer V700 is the original competition member of the Kumho high performance tire family. It is a DOT-legal, race-winning tire which, by capturing national championships at the Sports Car Club of America (SCCA) Tire Rack Solo II Nationals and SCCA Road Racing Runoffs, has proven its capabilities in both autocross and road racing competition.The VictoRacer V700 features an asymmetric tread design molded at 5/32″ to 6/32″ of tread depth in its two major circumferential grooves. Its tread design features extra wide tread blocks for its outer shoulder (which comprise about 1/3 of the tire’s tread width) to maximize cornering grip while promoting tread life (when new, the shoulder blocks are interrupted only by shallow, 1/32″ deep lateral grooves). The center and inner shoulder portions of the tread design are comprised of short, stable tread blocks to further enhance handling while providing some wet traction when new (or at near full tread depth). The V700 features a tread compound specifically developed to provide maximum grip, handling and treadlife.Internally the V700 has two steel belts reinforced with two nylon cap plies to help stabilize the tread area and provide V-speed rated (for 13″ & 14″ rim diameter sizes) or Z-speed rated (for 15″, 16″, and 17″ diameter sizes) capability. Additionally, three rayon carcass plies with sidewall stiffeners provide high temperature durability and quick steering response. Attractively priced, the Kumho V700 is designed to provide the best traction and treadlife for your racing dollar.Important Notice: Kumho VictoRacer V700 tires must be shaved to 3/32″ – 4/32″ of remaining tread depth for any track use in dry conditions.Kumho advises that the VictoRacer V700 DOT-legal competition radial must be shaved prior to use in dry track conditions. If this tire is not shaved, excessive wear may occur causing the tire to wear to the cords prematurely in a localized area.Tire heat cycling will not prevent the excessive localized wear of full tread depth tires but will continue to enhance the tire consistency and wear on shaved tires.The VictoRacer V700 should only be used at full tread depth (6/32″) on the track in wet conditions.Recommended Reading: Care and Feeding of the Kumho VictoRacer V700

Kumho VictoRacer V700

Technorati Tags: KumhoTire, V700, VictoRacer

The Ecsta (x’ ta) R700 is the performance rally competition member of the Kumho Ecsta high performance tire family. It is a DOT legal tire that has already been proven in Europe and Asia, and will be available in the United States through The Tire Rack.Kumho introduced its performance rally tires in England in 1998. The initial results were so encouraging that the Kumho Ecsta R700 was chosen for the Mitsubishi EVO 5 team for use in the final event of the 1998 World Rally Championship, the Network Q Rally of Britain. The Kumho tires finished the event without any punctures, sidewall penetration or allowing the tires to be pushed off of the rims. Not bad for a first run in a World Championship Rally event. Post-event tire analysis, combined with an extensive development program has helped Kumho further develop the Ecsta R700 rally tire which has now been used in World Rally, Asia Pacific Rally and British Rally Championship events.The Ecsta R700 is a purebred rally tire designed to take on the rigorous conditions of performance rally events. On the outside, the Ecsta R700 starts with a deep, open and aggressive independent block tread design developed to maximize dry and wet traction on dirt and gravel roads. The tread design also features sharp shoulder block edges to enhance sideways grip for more responsive handling and cornering traction on loose road surfaces. The upper sidewall has circumferential sidewall protector ribs to help protect the tire from cuts and snags while the lower sidewall features rim protector ribs to help prevent debris from pushing its way between the sidewall and the rim. On the inside, the Ecsta R700 tires feature twin steel belts reinforced by a nylon cap ply and a two-ply rayon carcass built with high ply turnups to provide four actual carcass plies in the sidewall for enhanced durability and cut protection.Kumho Ecsta R700 tires feature blackwall styling, are Q-speed rated and available in selected 80-, 70-, 65- and 60-series sizes for 13″ through 15″ wheel diameters.

Kumho ECSTA R700

Technorati Tags: Kumho Tires, RallyTires

Welcome to the rally.  Since you missed the live beginner’s meeting, I’ve tried to come up with a printed version that works as well as (or better than) the live version does.  This document should be helpful but it is unofficial.

WHAT IS THIS?

It’s a Time-Speed-Distance (TSD) rally, also called a Navigational rally.

WHAT IS THE OBJECT OF THE RALLY?

The object of a TSD rally is to arrive at each checkpoint ON TIME, Not EARLY and Not LATE.  There is a penalty for being Late or Early – the penalty is 100 points per minute, and it’s pro‑rated.  So, if you’re ½ minute late on one leg, it costs you 50 points; if you’re ½ minute early on the next leg, it costs you another 50 points.  That doesn’t fix it; it makes it worse!  On a rally, points are bad (as in golf); lowest score wins!  Unlike golf, it is possible to get a score of Zero on a leg.

Before you leave the start, make sure that you have at least one watch or clock that matches the official time; if you don’t know how to set your watch, at least know how far it is off and in which direction.

HOW IS ‘ON TIME’ DETERMINED?

Once you finish the Odometer Check (sometimes called the Odo Check or the Odometer Calibration), we will always tell you how fast to go.  The way we do that is primarily with the defined term CAST (which stands for Change Average Speed To).  When we tell you to CAST 30, it means that you should begin traveling at an average speed of 30 Miles Per Hour and keep doing so until we tell you otherwise.  When we refer to an average speed of 30, we mean that it should take you 2 minutes to travel each mile.  If the road is straight and has no stop signs, you can simply drive 30 MPH.  If the road has one or more stop signs, you have to stop for each one and then make up for the time you lost by traveling at a higher speed until you catch up.  If the road has sharp curves, you may have to slow down and then make up for the time you lose by going faster later in the straightaways.

Another way to understand an average speed is to imagine that a blimp is floating above the road, traveling at the exact speed that you’re assigned to go; but it is never delayed by traffic, curves, or Stop signs.  When you get delayed, you have to speed up until you catch up with the blimp.

WHAT ABOUT TRAFFIC LIGHTS?

We usually give you an assigned PAUSE to make up for the time you lose at Signals and some Stop signs.  Sometimes, we will give you a large Pause to make up for a group of Signals.  For example, if you go through 6 signals (some red, some green), and you lose a total of 3 minutes, and then we tell you to pause 3½ minutes, you would wait only the extra ½ minute at that point; not 3½ additional minutes!  If we only tell you to pause 3 minutes there, just keep going because you’re back on time.

WHAT’S THE ODOMETER CHECK?

There are differences between the odometers and speedometers of different cars.  If you know how the car that measured the rally compares to your car, you can adjust accordingly.  During the Odometer Check, just drive at a safe and legal speed, note your mileage at each sign or landmark where a mileage is given, and be prepared to do a little math with the 5 minutes you should have at the end of the Odometer Check.

·        Figure out whether your odometer gives a higher or lower reading.

·        Figure out the difference between your reading and ours.

·        Figure out what percentage (of our mileage) the difference represents.

For example, if the odometer check is 30 miles long and your odometer shows 33 miles, yours reads higher, the difference is 3, which is 10% (3/30 = 10%).  Use the saying “If you’re Low, Go Slow; if you’re High, Fly”.  Since your odometer reading was higher than ours, you should go faster by the percentage difference.  So, if we assign you to go 40, you should travel at a speed of 44 (10% faster than 40).  If your difference is less than 1%, the difference is too small to worry about in Beginner Class.

If we measured the rally in kilometers, you would find that on a 14 KM odometer check, your odometer would show 8.7 miles, a difference of 38% (under).  Thus, when we directed you to travel at a speed of 95 (Km/H), you would go 59 MPH.

HOW DO I DO THE ROUTE INSTRUCTIONS?

The numbered instructions are to be done once only, in numerical order; never skip an instruction; never do a numbered instruction more than once.  Complete each numbered instruction before you start the next one.

For instructions marked WOF (Whichever Occurs First), do whichever portion (separated by the word OR) that you can begin working on first, and skip the rest.  Otherwise, complete the parts of an instruction in order.

Parts of instructions that are in parentheses are helpful only; the part in parentheses will be both helpful and correct.

When we put something in quotation marks, we are referring to the text of a sign; otherwise, we are referring to something else (such as a road or a term defined in the Definitions and Abbreviations).  Unless the quotation is marked SOL (Sign On Left) or SA (Sign Anywhere), quoted signs must be on your right.  Signs may be facing you or off to the side, but you’ll never have to look back to see them.

The following applies both to quoted signs and road identification:  We may refer to the full text or any continuous portion.  West Topanga Canyon Blvd can be referred to as Topanga, or as Canyon, or as West Topanga, but not as Topanga Cyn. (an abbreviation is not the same as the spelled out word), nor as West Canyon (not a continuous portion since Topanga was omitted).

Some instructions don’t direct a specific action; they just mention a Sign or a Landmark; such instructions are considered completed as soon as you reach the indicated Sign or Landmark.

Lettered instructions work differently than the numbered instructions.  Once you have completed the numbered instruction before a lettered instruction, you have 2 things to do.  You begin looking for a chance to do the lettered instruction and you begin looking for a chance to do the next numbered instruction.  You keep looking for chances to do the lettered instruction until it is cancelled.  A lettered instruction might be done once, more than once, or never.  A lettered instruction can be cancelled by an instruction that directs you to cancel the lettered instruction or by a checkpoint handout.  One lettered instruction does not automatically cancel the previous lettered instruction; there may be more than lettered instruction active at the same time.  A multi-part lettered instruction must be executed in full before you can execute it again.

If you come to a place where both a numbered instruction and a lettered instruction conflict or direct the same course action, do the numbered instruction there.

CHECKPOINTS:

At a manned checkpoint (marked by a sign with a Check mark and a Point), there will be a hose across the road, similar to a service station of yesteryear.  Don’t stop at the timing line; instead, slow down and stop when you get to the checkpoint workers.  It’s a good idea to note the time you crossed the timing line (but not on the Control Card).

Hand your Control Card (detached from your rally materials, and filled out with your names, addresses, etc.) to the worker.  The worker will mark the time you arrived in Hours, Minutes, and Hundredths of a Minute (not in Seconds).  When you get your Control Card back, double-check your arrival time with the time you crossed the line (converting your seconds into hundredths of a minute using the conversion chart).  If it’s close, great; if not, let the worker know.  It’s possible they lost track of which time belonged to which car and gave you the time of the car before/after you.

The Start Time for the next leg will be marked on your Control Card.  You will get a checkpoint handout that includes the speed to begin the next leg, the active instructions, and any special instructions or official information.  Previous lettered instructions are cancelled if they are not listed as active.  Any numbered instructions skipped are cancelled.

A few items of rally etiquette: Once you cross the timing line, you are no longer in any hurry!  Don’t pass other rally cars between the timing line and the checkpoint; stay in the order in which you crossed the timing line.  At the Out Marker (where you start the next leg), bear in mind that cars are assigned to leave at one minute intervals; don’t block the sign until there is less than one minute until your Start Time.

WHAT’S A DO IT YOURSELF CHECKPOINT (DIYC)?

When you are instructed to DIYC at a specific point, note the time you arrive at the specified Sign or Landmark.  Write that time, in Hours, Minutes, and Hundredths of a Minute (NOT Seconds – use the conversion chart) in the first available Time In box on your Control Card.  Write a time that is exactly 1 minute later in the first available Time Out box.  Note that the times you write will not be in the same column; one will be the Finish Time for one leg and the other will be the Start Time for the next leg.  For example, if leg 2 ends with a DIYC, you write your Finish Time in the Leg 2 column and your Start Time in the Leg 3 column.

Be sure to leave the DIYC when your Start Time for the next leg occurs.

A DIYC can be your chance to adjust if you are slightly late.  If you are ½ minute late when you get to a DIYC, adjust your arrival time down by ½ minute, and leave 1 minute after you should have arrived.  If you are exactly a minute late, adjust your time down by 1 minute and don’t stop.

WHAT IF I GET LOST?

If you figure out where you went wrong, go the right way; however, there is a maximum penalty of 5 minutes per leg.  So, if you are 10 minutes late, you won’t have to drive unsafely to catch up.  A manned checkpoint should still be open unless you are more than 20 minutes late.

Sometimes, if you are lost and you see 2 consecutive route instructions that specify road names, such as RI 21 – R on Smith, RI 22 – L on Jones, it’s a fair bet that RI 22 will be a turn from Smith to Jones.

If you quit the rally for any reason (got lost, car sick, car trouble, paged to go to work, whatever), be sure to call the finish location; its telephone number is usually listed in the final route instruction.

SPECIAL STUFF

There are special rules that apply when you are directed ONTO a road by name/number (using the word ONTO), and when you are directed to FLR (Follow the Lined Road).

Two things happen once you’ve done such an instruction:

1)     You must follow that road.  For ONTO, this means continuing to follow the road by name or number; for FLR, this means continuing to follow the Lined Road.

2)     The next R/L/TURN you do must cause you to travel a different course than the active ONTO/FLR.

Imagine the following scenario:

You’re instructed ONTO Smith.  The next route instruction is R at 1st OPP (Opportunity).  The first Intersection is a T where Smith goes right and another road goes left.  You would go right there because of ONTO, not because of the route instruction.  The next Intersection (to the right of the first one) is a T where Smith goes left and another road goes right.  You would go right there because you can turn right there so as to travel a different course than ONTO (which was to the left).

I’VE FALLEN BEHIND; HOW DO I CATCH UP?

The easiest way to catch up is to skip a pause.  If you are 3 minutes late and you are instructed to pause 2 minutes, you are now only 1 minute late.

Maintain a continuous log of how early or late you are.  Each time you are delayed, subtract the delay time from the running total; each time you gain some time, add that time.   Use hundredths of a minute in your log.

Example of a log: (you would write only the numbers, not the comments)

–50    (Stopped ½ minute at a Signal)
–150  (Stopped 1½ minute at the 2nd Signal)
–200  (Take a subtotal every chance you get)
+300  (Instructed to pause 3 minutes)
+100  (Now you’re a minute early!  Always include a ‘+’ or a ‘–’ )
–25    (Stopped at a Stop sign)
+75    (Still early)

To approximate the time you lose at a Stop sign or Signal, start a stopwatch at the point where you get down to half the assigned speed, and then stop the stopwatch at the point where you get back to half the assigned speed.  This even works if there is a speed change at a Stop sign.  If the assigned speed as you approach the Stop sign is 30, start the stopwatch when your speedometer shows 15; if the new speed change at the Stop sign is 40, stop the stopwatch when your speedometer is at 20.

This approximation technique also applies when you are instructed to pause.  If you get all the Signals green and you are instructed to pause 3 minutes, (and your assigned speed is 50), you would start and stop your stopwatch as your speedometer crosses 25.

Here’s a technique for gaining time along the course.  If you travel X% faster than the assigned speed for 1 minute, you will gain X% of a minute.  For example, if you travel 25% faster than the assigned speed, you will gain 25% of a minute (¼ minute=15 seconds) per minute; do that for 4 minutes and you will have gained 1 minute.

Let’s try this on a 10‑mile stretch of road where the assigned speed is 40 MPH.  At 40, 10 miles takes 15 minutes since each mile takes (60/40=)1.5 minutes.  At 50, 10 miles takes (60/50 x 10=)12 minutes.  During the 12 minutes that you drove, you gained (12 x 25 %=)3 minutes, arriving (15‑12=)3 minutes earlier than someone going 40.

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Technorati Tags: 1st time TSD Rally, Autombile Rally, Car Rally, car rallye, First Friday niter, Fun things to do with your car, fun with cars, Fun with your car, Navigational Road Rally, Road Rally Forum, Santa Monica Sports Car Club, SMSCC, Southern California Rally, Southern California Road Rally, TSD Rally

I remember running a monte style road rally, written by friend Ron, that was titled Zero Zeros. What did he mean by this. Luckily I figured it out. The trap of one leg was that the checkpoint was on a dead end road, yet the generals stated that missing a checkpoint was a 200 point penalty and that going through a checkpoint backwards was a 500 point penalty. Therefore is was an impossilbility to score a zero on the the leg. You eather got a 200 or a 500. About 1/2 up the dead end road to this infamous checkpoint, I realized the devilishness of my so called friend Ron, and what the title of the event meant. I immediately turned around and headed for the next checkpoint. By getting a 200 on that leg and not the 500 like everyone else, I won!

Some rallyist I know, are a ceratin class of people, and I know this article will impress the heck out of them. It is circa 2004, so the equipment has improved since, but the basics are the same. This article was published around June 2004 and was written by Kurt Dost

Now the meat of this article, another way to get the elusive zero score on a TSD Rally.

A GPS Solution for TSD Rallies

The SWRallyComp system

In order to match the rallymaster’s perfect time, rally teams use clocks that display fractions of minutes and not seconds, which will be the format for times shown in this article. Also, the perfect time will usually be truncated to 100ths of a minute, or two places, and these fractions of minutes are known as cents. TSD rally scores represent the deviation in cents from a perfect time. So, for our example, team A’s car arriving at the checkpoint at 12:06.72 would score a 0.

A TSD rally is not a race and arriving early is as “bad” as arriving late. For example, if a team arrives 2 hundredths of a minute early (12:06.70), then it receives a score of 2; if 33 hundredths of a minute late (12:07.05), a score of 33. A team cannot make up arriving late at a checkpoint by arriving early at the next, as each leg is scored independently. A rally consists of many legs, and the winner will be the team with the lowest cumulative score over all legs.

Measuring the Distance: The basic idea in rally computation can be stated in one of two ways: Given a starting time and the current time, at the CAST(s) assigned, have you traveled the correct distance? For example, if Team A was to start at 12:01.00 at a CAST of 32 and it is now 12:03.17 has the car traveled 1.158 miles? Or, given the mileage traveled at the CASTs assigned, does the current time match perfect time? For example, if Team A was to start at 12:01.00 at a CAST of 32 and the vehicle has traveled 1.158 miles, is the current time 12:03.17? Both these computations require that exact distance measurements are available to the rally navigator.

figure 2 A wheel turn sensor can be used to calculate distance traveled.

In calculating perfect times, the mileage is measured to thousandths of a mile. This is much more accurate than a standard automobile odometer is capable of showing – typically only displaying tenths of miles – but not actually of measuring. The rallymaster will use a precision odometer that reads out to three decimal places to obtain mileage between NRIs and then, using the same method as in the example, compute perfect time.

figure 3 SWRallyComp TSD configuration

Most precision odometers work by using a magnet attached to an axle or wheel and a Hall effect sending unit, or transducer, which triggers upon detection of a strong magnetic field. Each turn of the tire will cause one pulse to be picked up by a computer, which will then simply add a value known as the calibration factor distance into the odometer, as seen in Figure 2. This calibration factor is based on the formula: pi 2 (Tire) Diameter 4 Circumference.

The calibration factor is usually expressed as a fraction of a mile, the number representing how far the vehicle travels for each revolution of the tire. What is needed now is the diameter of the tire that is on the vehicle to which the precision odometer is attached. This is found using the formula:

For a vehicle equipped with tires having a specification of P205/70R15 the formula yields 26.299 inches for the tire’s diameter and hence a circumference of 6.8851 feet. Thus, each pulse resulting from the wheel rolling along the road means the vehicle will have traveled 6.8851/5280 or .00130399 miles. This will be the calibration factor used for the precision odometer. Note that this is a theoretical value that won’t exactly match the rallymaster’s mileages and must be adjusted. All rallies allow for this adjustment in a segment of the rally known as the odometer calibration run to reflect real world conditions, such as tire load, tire inflation and road conditions.

In the 1980s, several hardware manufacturers – including Alfa, Terratrip, Zeron and Timewise – integrated precision odometers with a device to compute whether a TSD team was on time given the target CASTs. Some of these units are still manufactured and can cost up to $1,000.

The GPS Alternative John Fishbeck had competed in rallies in the 1960s when all that was available were mechanical calculators, such as a slide rule, along with paper and pencil, to compute in real time how close the driver was to maintaining perfect time. Now in the 21st century, having both a laptop computer and affordable portable GPS receivers available, he decided to develop a custom software-based rally computer, the SWRallyComp.

TSD rallies provide for several classes of competition. For instance, stock class allows a four-function calculator to be used. Equipped class allows any distance measuring equipment to be directly connected to any calculating device, which is the class the SWRallyComp is designed for. Figure 3 depicts the configuration of the system.

Several concerns were on the table in developing the SWRallyComp. One was whether a laptop running a Visual Basic program could effectively compute and display the necessary information in real time. Second, and more importantly, would the GPS fixes be accurate enough to compete with a precision odometer-driven rally computer.

The 12-channel receiver used in the SWRallyComp system includes a digital mapbase and display, graphical user interface, waypoint navigation, and the ability to use the Federal Aviation Administration’s Wide Area Augmentation system for DGPS positioning. The unit allows an external NMEA (National Marine Electronics Association standard) device, differential GPS (DGPS) beacon receiver, or portable computer to be connected to the GPS receiver through its serial port. Several formats are available for data transfer, one being the NMEA out setting. This setting results in the NMEA 0183 version 3.0 data being sent every two seconds to the serial port.

Corner Tracking Errors Developing a GPS-based distance-measurement alternative to a wheel turn sensor required close consideration of the road geometry of TSD rallies and the positioning function of a GPS receiver. A wheel-turn sensor and odometer use dead-reckoning techniques that link subsequent measurements directly to previous positions. GPS position fixes, however, are independent measurements that don’t necessarily account for a car’s travel along a road network with sharp corners.

figure 4 A GPS-based TSD rally computer needs to compensate for potential distance-measurement errors encountered in corners where the apparent distance between two position fixes t01t1 creates a shorter distance than the one actually traveled (t01tx1t1).

For example, one of the concerns with obtaining GPS fixes every two seconds is demonstrated in Figure 4.

Assume the GPS fixes are taken at times t0, t1 and t2. The distance computed for Team A’s car for interval t0-1, segment t01t1, does not reflect the distance needed to negotiate the corner, segments t01tx and tx1t1. The computation for straight-line interval t1-2 is inherently more accurate. A smooth radius curve exhibits this same problem.

figure 5 The geometry of the corner tracking problem for GPS

Increasing the GPS receiver’s positioning rate will reduce this corner tracking error. The GPS receiver used in the SWRallyComp can be set to use a proprietary format. This setting results in the PVT (position, velocity, time) Data Protocol being used to provide the PC with real-time PVT data, which is transmitted by the unit approximately once per second. Most club rallies are run at speeds from 25 to 45 mph, which means the vehicle travels anywhere from 36.67 feet to 66.00 feet every second. The one-second update yields a fix rate more in line with the needs of a car traveling 45 mph around curves in contrast, for instance, to a boat traveling 12 knots in a straight line on open seas.

Figure 5 provides an illustration of the corner tracking-error issue when negotiating a curve in a road. Team A is approaching a 90-degree turn. The radius r (radii OA and OB) of the turn will vary based on county road commission specifications. Assume the GPS obtains a fix every second, one at position A and one second later at position B. Depending on the speed of the vehicle, it will travel a distance along the arc AmB before the GPS will update its fix. The computed distance will then be chord AB.

Several similar arcs will comprise the 90 degree turn. The associated chord/arc discrepancies in distances are enumerated in Tables 2 and 3. (Radius figures are based loosely on the American Association of State Highway and Transportation Officials policy for expected vehicle speed through a curve for typical county aggregate roads on which rallies are run.)

The “overall difference” column shows the number of feet that are computed for the 90-degree turn short of what was actually traveled. The net effect of this for TSD rally purposes is that the GPS-driven rally computer will show it has traveled less distance than it actually has over the route. This will result in a team arriving earlier than they should at the checkpoints.

GPS Accuracy Accuracy can be expressed as the degree of conformance between a GPS receiver’s computed position and that of constant standards of reference, such as the World Geodetic System 1984 (WGS84) or regional map datums. Now that the practice of degrading the GPS signal – selective availability (SA) – is just a distant, unpleasant memory, a number of GPS receivers will provide absolute position accuracy within 15 meters. Using one of the real-time DGPS systems can reduce that error to within 3 meters, but this level of accuracy is not considered necessary for our application. This metric is usually termed absolute accuracy.

Another measurement can be termed relative accuracy, which does not reference an external standard. Relative accuracy is the ability to return to a visited position at a later time. Relative accuracy can also be a reflection of how static a fix remains. How do these accuracy measurements affect the use of a GPS for odometer computations?

The metric of absolute GPS accuracy can be thought of as follows: If I take a position fix at a landmark on earth, how close is the GPS fix to the actual coordinates of the landmark? For surveyors and pilots the answer to this question can be very important. If a pilot landing an airplane expects the end of Gerald R. Ford International Airport’s Runway 8R to be at 46° 52.59803′ N, 85° 32.53103′ W and the plane’s GPS receiver has a 10-meter error, then a problem could arise. This error is induced by several factors, most being of relatively long duration. For example, ionospheric conditions that delay the propagation of GPS signals from a satellite are noticeably affected as the Earth rotates with respect to the Sun but do not change greatly from minute to minute.

The relative metric is the more important to a rally GPS system. This measure of accuracy can be thought of as follows: Given a fix at position A, then moving a relatively small distance in a relatively small period of time to position B or, for that matter, remaining at position A, will the GPS receiver compute the difference, if any, correctly. Note that relative accuracy has nothing to do with absolute accuracy, as long as each fix is obtained under the same conditions. For purposes of distance measurement, a rally computer GPS fix does not need to be as accurate as a surveyed location, only that it is accurate relative to itself.

Figure 6 A stationary GPS receiver showed this progression of position fixes during a two-minute period, reflecting the uncorrected errors in pseudoranges to the satellite.

Each fix given by a GPS receiver has an estimated position error that can be visualized as a circle encompassing a percentage, ranging from 50 to 95 percent, of the fixes output. For the GPS receiver used in the SWRallyComp, this figure typically is between 5 and 10 meters. An important aspect of the relative error is that every position reported is not randomly scattered within this circle. In fact, for a non-moving GPS receiver each position output, though wandering, will be relatively close to the previous.

Figure 6 shows the progression of the position fixes at one second intervals for a stationary SWRallyComp unit. Using the data depicted in Figure 6, Figure 7 indicates the difference in feet each fix position is from the prior fix.

Figure 7 Distance in feet that each position fix shown in Figure 6 is from the prior fix.

The average for the values in Figure 7 is .337 feet or 4.04 inches. Even though the differences are not zero and seem rather large for a stationary receiver, what effect will the relative error have on the SWRallyComp? First, this characteristic of fix positions moving though the rally team is stationary, for example at a stop sign, will result in the computer accumulating mileage as if moving, albeit very slowly. Secondly, for times when the team travels on roads heading north, south, east and west, will this relative movement cancel out?

The pattern in the progression of the fixes results in an inaccuracy in a direction. Assuming the direction bias or progression would be exhibited in the same direction regardless of the GPS movement, then some fix positions would result in more distance being calculated and some would result in less distance. For example, in Figure 6 several readings trend along longitude (radians) 1.4709644, with only small latitude changes.

If a vehicle were heading north at this time, then on average 4 inches would be added to the distance-traveled calculation in the one-second interval. However, if the vehicle were traveling south, then the distance computed would be short four inches. Given that each leg of a rally entails several directions of travel it would seem that these relative errors would, in effect, cancel out over the course of the event.

Functions of a Rally Navigator The navigator’s role is two-fold. First, he must assist the driver in staying on the prescribed route. This is done by using the NRIs provided by the rallymaster and making appropriate observations and decisions, such as noting what road to turn onto.

Second, in the non-equipped class, the navigator must provide the driver with a discrepancy in either distance or time from that of perfect distance or perfect time. Either value can be obtained using the CAST in effect and another known component of the TSD formula.

To obtain the mileage discrepancy, the navigator will take the CAST and multiply it by the time that they have been running at that CAST. For example, a CAST of 35 run for 1.50 minutes should place the car exactly .875 miles farther into the route from whence the CAST went into effect. The driver can then look at the odometer to see if they are over or under that distance. How much over or under is called the delta distance.

This delta distance is most often turned back into a time difference by dividing it by the CAST to give the driver a delta time. The delta time is given as a positive number to indicate the team is ahead of where they should be on the course, or as a negative number if behind and, hence, the driver should increase speed.

Of course, any general laptop computer can perform these functions much more quickly, and the navigator’s role in equipped class becomes one of route following and making sure CAST changes are put into effect at the correct NRI and at the precise landmark.

Functions of a Rally Computer All rally computers must be able to perform several basic functions, such as allowing input of leg starting times, mileages, and CASTs. It will then compute the needed information based on mileage data, input either manually or automatically.

figure 8 The rally computer's driver module.

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The SWRallyComp, using mileage input derived from the GPS, allows the navigator to use function keys to effect pertinent actions at the appropriate time. Several of the function keys will bring up dialog boxes in which to enter data. We should note that the use of a laptop keyboard can be somewhat difficult in a car negotiating a corner at speed on a rutted gravel road. Figure 8 shows the main SWRallyComp form display.

The LCD driver module, shown in Figure 3, is mounted in front of the driver to provide pertinent information without having to look over to the laptop screen. The driver module can be configured to displayed specific fields. The following fields are on the SWRallyComp main screen:

Time Difference. The amount of time, in minutes and cents the team is ahead or behind perfect time. This value is also displayed on the driver module.

Actual Time. The time of day. The rallymaster and checkpoint workers will use time of day for leg start times. This time must be in synchronicity with the rallymaster’s clock. This is also known as current time.

Perfect Time. The time as computed using CAST’s and NRI’s given by the rallymaster. This value is computed based on the distance measuring equipment attached to the computer.

Miles to Tgt. This can be input if the NRI’s are mileaged. This mileage counts down to give the driver notification as to when to execute the next driver relevant action. This field can be displayed on the driver module.

Car Odometer/ Official. Mileage as accumulated on the rally leg or section. The Official mileage applies the Odometer CF (correction factor) value, as obtained on the ‘odometer calibration’ section of the rally.

CCAS/CAS. Change Average Speed To value in effect as indicated in the NRI’s. CCAS value applies the Odometer CF. This value is displayed on the driver module.

Next CCAS/Next CAS. Next CAST change. This will be the next value as indicated in the NRIs.

The navigator has the following function keys to effect TSD rally computations:

F1. Dialog Box: Set the leg start time, mileage and CAST. At the beginning of the rally each team is assigned a start time; thereafter, a rally worker at each checkpoint gives this to the team.

F2. Dialog box: Execute NRI. This makes an entry into a running log file, noting current time, perfect time and mileage. Useful for recovery purposes when the navigator discovers the team is off course.

F3. Dialog box: Set the next CAST. Allows the navigator to input the upcoming CAST as shown in the NRIs.

F4. Dialog box: Execute the CAST change. This will swap CAST and Next CAST.

F5. Dialog box: Execute a checkpoint. This makes an entry into a running log file.

F6. Dialog box: Adjust perfect time. Allows the input of PAUSE or GAIN values as shown in the NRIs. Pauses are input in cents; for example, a half-minute pause is input as 50.

F7. Dialog box: Allows navigator to modify the accumulated mileage (Official mileage).

F8. Dialog box: Allows navigator to modify the Odometer CF.

F9. Allows the navigator to PARK the computer when the car is stopped. This turns off any accumulation of mileage from the GPS. This is important, as the GPS will measure distance even if stationary. See Figure 6.

F10. Reverses the mileage accumulated. In effect subtracts the distance computed from the accumulated distance (Official mileage) in order to retrace portions of the route.

F11. Displays the running log in NOTEPAD. This is useful for recovery purposes (see function key F2).

Comparison of Systems Does the SWRallyComp GPS-based distance measuring paradigm compete with a hardware specific solution? We speculated that the errors introduced by GPS might make the system too imprecise. We also posited that the errors might cancel out, resulting in a fairly accurate system.

To test these hypotheses, on January 10, 2004, we used the SWRallyComp in the Son of Sno*Drift rally organized by members of the Detroit Region of the Sports Car Association of America (SCCA). Table 4 demonstrates that a rally run using the SWRallyComp with the 12-channel C/A-code receiver will allow a team to achieve zero point legs.

The leg values show whether a team is early (negative values), or late (positive values). The SWRallyComp has a propensity to calculate less distance than the rallymaster’s distance. This probably is because of the corner tracking error. Also the rallymaster may compute more distance for a leg as the result of tire slippage error that a drive train system introduces. In other words, “spinning out” will cause a wheel-driven odometer to measure more distance between locations than actually exists. Both errors result in the rallymaster ascribing more distance in the leg than the GPS-based system calculates. This may cause a rally team using the GPS-based system to arrive early at checkpoints.

Though the Fishbeck & Dost rally team does have some zero-hero scores, Leg 4’s error stands out. It would seem that the GPS relative errors cancel out in most cases. Leg 4’s distance measurement error resulting in the incorrect perfect time computation may have been caused by loss of satellite signal or multipath error.

Conclusion Stand-alone GPS fix information provides accurate enough positional change data to be used as an odometer input for a rally computer in equipped class, though not yet with the precision needed to achieve consistent perfect times. This seems to be a result of each GPS fix’s relative error being small and tending to cancel out as the vehicle’s direction changes over the course.

Further accuracy may be possible through updating fix positions faster than every second, which would decrease the corner tracking error. Mounting the external antenna outside of the vehicle, as opposed to an internal windshield mount, might increase signal strength. Finally, with a GPS modernization plan under way, nationwide real-time kinematic DGPS may yield positional data that will rival drivetrain-based precision odometers. c

Manufacturers The SWRallyComp developed by John Fishbeck used a GPS V receiver from GARMIN International, Olathe, Kansas. The laptop is a SlimNote Model P86 from Twinhead Corporation, Fremont, California, with an Intel Pentium II processor, 64 Megabytes of memory, with one serial port and one USB port used for attaching the GPS receiver and LCD Driver Module. The USB port/LCD Driver Module connection uses a USB/RS232 converter cable as the Driver Module’s interface is RS232. The operating system is MicroSoft Windows 2000 Professional.

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Planning on attending your first road rally and not sure what to expect, or how to make your first outing a success? First you need to make sure you define “success” of a first time road rally. If you set your goal of a first time rally to winning and taking home a trophy, my guess is you will be mistaken. If you set your goal a first road rally success as starting the rally and finishing the rally, no matter what position, without wrecking your car or tearing the head off of your navigator, then you are right on track!

Road rallies can be fun and intense at the same time. There are several rally event types. I personally like them all, some better than others though. To learn more about the different types of rallies, read on, to locate a rally event to attend, visit RallyRoutes.com.

Selecting an event can be the first challenge, should you go on a TSD rally, a Monte Style Navigational Rally, or how about a gimmick rally?

Road rallies fall into one of three categories:

* Road Rally – Where the rally team arrives at checkpoints along a timed route and scoring is based on correct arrival time at checkpoints, with penalties for early or late arrival. The checkpoint or inmarker locations may be known or unknown. Most events are held on open public roads. Examples: TSD (time -speed-distance), Monte Carlo, Tour (TSD with no traps), Course (TSD with traps).

* Gimmick Rally – With a gimmick rally scoring is usually based on completing an answer sheet with information found along the route. A specific maximum amount of time or completion by a specific time of day may be specified. Events are held on open public roads. Examples: A&B, Course Marker, Photo, Map Clue, Poker Run, Hare and Hound.

* Performance Rally – Racing against the clock. Scoring is based on fastest time over a closed course. Cars need to be race prepared with rollcage, harnesses, helmets, fire extinguisher, competition license, etc. Examples: Rally Cross, Club Rally, Pro Rally and WRC.

There are many variations of these basic forms. Some rallies are timed in seconds; some in hundredths of a minute.  Some events specify average speeds, while others specify the exact time of day you are expected to arrive at identified locations. Route instructions may be written out plainly in words in sentences, cryptically encoded in abbreviations and defined terms, drawn in diagrams and pictographs, or your route may be highlighted on a map or indicated by splotches of white lime along the side of the road.

Although there are many types of events calling themselves road rally, there are a few things they all have in common:

* An entry team consisting of a vehicle, a driver, and a navigator

* A start location, a route, and an ending location

* Rules of the game, mostly known as generals and route instructions

RallyRoutes.com is centered around the Raod Rallies put on by local reginal sports car clubs where little to no modification to the entry vehicle is required. Please enjoy!

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