A Proud Moment

There is a cub scout in my den whose name is Brett Ott. He missed out on our Pack’s Pinewood Derby Race. When it came time to have the district race he showed up and said that he wanted to race. In his hands were two cars that were very obviously cub scout built, crude and rough, but of course beautiful as all cub-built cars are.

It so happens that we have an open class in our district race where anyone can enter a car as long as it passes the same inspection as the cub scout cars. Since the other classes were only for the first place finishers from the packs of our district, I told Brett that he would have to race in the open class with all of the fathers, mothers, sisters, brothers, etc. This included running his car against mine and some other ‘pineheads’ like myself. There was a large showing of open class cars this particular year, so his chances of placing seemed to be zip. But he would get to race.

He said, “I don’t know which car to race,” as he held out the two cars that he had brought with him. I looked both of them over and suggested the car which looked to have the best chance of performing. I weighed the car which was quite light. I took him over to the pit stop area where we quickly hot glued some lead to the top of the car. We graphited the wheels and ground in the lube by rolling the car back and forth on the counter. Then I placed the car with the rest of the open class cars, told him when they would race and then went back to the business of getting the other hundred and twenty cub scout cars registered and set in place for racing.

The races went on through the day with much excitement. Finally it came time for the open class races to occur. Off they raced with over 30 cars competing. Then the dust cleared and the results were announced. “In 3rd Place,” I yelled , “In the open class racing against many adults, the winner of the Thunderbird district 3rd Place trophy is BRETT OTT!”

I think that I was every bit as proud of him as I was of my own 1st Place finish in that race, possibly even more excited as I became quite emotional and choked up when presenting him with his trophy. He had produced, nearly all by himself, one of the fastest cars in the district, without the knowledge of how to do so. This after missing out in racing with his fellow scouts in his pack. This was a proud moment.

Randal Veenker
Cubmaster, Pack 248
Sandy, Oregon

From Pinewood Derby Times Volume 3, Issue 9

To subscribe to this free e-newsletter, please visit:
www.maximum-velocity.com/subscribe.htm

(C)2012, Maximum Velocity, Inc. All rights reserved.
www.maximum-velocity.com

The Big Debates – Aerodynamics

As your recall, the big debates were introduced in 2002 and are as follows:

1. Best weight position – discussed in Volume 2, Issue 4
2. Number of wheels on the ground – discussed in Volume 2, Issue 4
3. Best wheelbase – discussed in Volume 2, Issue 6
4. Best lubricant – discussed in Volume 3, Issues 1 and 4
5. Value of canted wheels – discussed in Volume 3, Issue 6
6. Importance of aerodynamics(1)

We have now arrived at the last of the big debates; the importance of aerodynamics on pinewood derby cars. In this article, we will answer the following questions:

1. Does aerodynamics have any effect on pinewood derby cars?
2. If so, what steps can be taken to minimize the effect?

IS THERE AN AERODYNAMIC EFFECT?

I have always believed that the effect of air flow over a moving pinewood derby car was slight to none. This conclusion was drawn from reading several booklets (including speed tip booklets for sale over the internet), from comments made on web sites (e.g., “I’ll prove that aerodynamics play no part by running a plain block of wood in a race”), and from observing that the maximum speed of a pinewood derby car is only about 10 MPH. Certainly, air flow can’t slow down a car running at 10 MPH. Or can it?

But then I reviewed some (unpublished) testing done by Michael Lastufka and found that a distinct aerodynamic effect was measured. So I decided to find out for myself.

EXPERIMENT
In order to measure the effect of aerodynamics, I used a test car (previously described in Volume 3, Issue 6). The car is 3/4 inch high, but can be equipped with a small air barrier which brings the height at the front of the car to 1-1/4 inches (same as raw BSA block), or with a large air barrier which brings the height to 1-3/4 inches (see Figure 1).


Figure 1: Test Car Air Barrier

The car was raced once without a air barrier, then with the small barrier, and finally with the large barrier. This process was repeated 10 times, with all heat times captured by an accurate timer. All factors other than the air barriers were unchanged.

RESULTS
The results of the experiment are shown in the table below. In addition, Figure 2 shows a plot of the front surface area of the car versus the performance. As you can see, the air barriers had a distinct, and virtually linear effect on the car’s performance. In other words, the heat times decreased in proportion to the surface area decrease.

Front Size(Sq. In.)

No dam 1.3125
Small 2.1875
Large 3.0625


Figure 2: Surface Area versus Heat Time

Thus, this experiment shows that there is an aerodynamic effect with pinewood derby cars, and that the effect is significant.

COMPARISON STUDIES
As a comparison, here are two other studies that show similar results:

1. A several year old study which measured a block shape against an aerodynamic shape. The results indicate a 0.027 decrease in heat time for the aerodynamic car versus the block car.

2. In the unpublished study by Michael Lastufka mentioned earlier, two sizes of front surface areas were used. The smaller front surface was 2.6 square inches, while the larger front surface was 7.6 square inches. The results were that the smaller front surface outperformed the larger front surface by 0.078 seconds.

MINIMIZING THE EFFECT
Now that an aerodynamic effect has been demonstrated, how can the car builder minimize the effect? Here are several thoughts:

1. Low-profile cars (smaller surface area as viewed from the front of the car) will tend to outperform higher-profile cars.
2. Cars should taper from a smaller surface area in the front to a (possibly) larger surface area in the rear.
3. Edges running across the car should be rounded or tapered.
4. Wings, sails, flags, pennants, etc. add to the surface area, thus they tend to decrease performance.
5. Unfilled holes (major holes) can catch air and slow down a car.

CONCLUSION
One of the fun aspects of participating in a pinewood derby race is seeing the wide variety of cars that are entered. This article is not meant to stifle that creativity, but simply to make the builder aware that aerodynamics do play a role in car performance. By recognizing this fact, car builders can make adjustments in the car profile that could pay big dividends at the finish line.

(1) Aerodynamics – As used in this article, aerodynamics refers to the effect of air on the movement of a pinewood derby car.

From Pinewood Derby Times Volume 3, Issue 9

To subscribe to this free e-newsletter, please visit:
www.maximum-velocity.com/subscribe.htm

(C)2012, Maximum Velocity, Inc. All rights reserved.
www.maximum-velocity.com

Pinewood Derby Memory – Better Lucky than Good

This happened years ago when my son was still racing. He is an Eagle scout now, and I am now enjoying pinewood derby racing with my grandson.

The second year my son raced his car, I had to work and was not able to be at the race. He had come in 3rd Place at the race the previous year, but came in 1st Place the second year. The top 4 finishers went to the district race.

Before the district race, we spent what seemed like hours polishing, lubing, aligning – everything we knew to do.

After the check-in at the district race, we were walking around looking at some of the other cars. One of the boys in our pack had a car that would not pass inspection. He had rounded the wheels. This was not caught at the pack race – I’m sure that he didn’t know that this was not allowed. I told him that we had brought another set of wheels, and if it was OK with the judges he was welcome to use them. We had not done anything to these wheels, not even removed the mold marks. The boy added some graphite, and then put them on the car.

Even though my son’s car had beaten him at the pack event, this boy placed 7th or 8th out of about 80 cars, well ahead of my son. That goes to show that it’s sometimes better to be lucky than good!

Kenny

From Pinewood Derby Times Volume 3, Issue 7

To subscribe to this free e-newsletter, please visit:
www.maximum-velocity.com/subscribe.htm

(C)2012, Maximum Velocity, Inc. All rights reserved.
www.maximum-velocity.com

Speed Tip – Repairing a Dent

Actually, this is really a construction tip but it seemed like a good one to share so please bear with me.

As you know, pine is a very soft wood and it seems to me that it gets little dents in undesirable places all too easily (some swear that just looking at it is enough!). If the dent is deep, wood putty (or another type of filler) is the solution. However, for small dents on edges, putty doesn’t always work. Instead try this:

1. Use an eyedropper to place a few drops of tap water on the dent.
2. After a minute, use a needle or pin to poke a few shallow holes in the dent.
3. Apply a few more drops of water and allow the wood to dry.
4. Sand and continue the building process.

Oftentimes this treatment will swell up the grain, eliminating all or part of the dent.

From Pinewood Derby Times Volume 3, Issue 7

To subscribe to this free e-newsletter, please visit:
www.maximum-velocity.com/subscribe.htm

(C)2012, Maximum Velocity, Inc. All rights reserved.
www.maximum-velocity.com

Elimination Race Methods – Let’s Make Some Improvements

For many years, our organization used a double-elimination method for staging pinewood derby races. As I observed the staging and outcome of these races, I saw cases where the fairness of the race could be questioned. As a result we implemented several improvements to minimize these cases. Eventually, with the acquisition of race management software, we moved away from an elimination method.

While the popularity of finish line electronics and race management software has made a dent in the number of races using an elimination method, it is still one of the most common methods for staging pinewood derby races. While I personally recommend using an alternate method, organizations will continue to use elimination methods far into the future.

So let’s dig further into this method of racing. We will first take a quick look at the basics of elimination methods, look at the pro and cons, and then see what can be done to improve this method of race staging.

WHAT IS AN ELIMINATION METHOD

The basic characteristic of an elimination method is that entrants are incrementally eliminated from the competition until only the winning entrants remain. Thus, in pinewood derby racing as the races progress, cars are eliminated from the competition, narrowing the field down to the fastest cars.

The most common elimination method is a double-elimination. In this type of race, a car stays in the competition until it has lost two times. However, other elimination methods can also be used. For example, in a single elimination race, cars are eliminated after one loss, while in a triple-elimination, cars are eliminated after three losses (three strikes, you’re out).

ADVANTAGES OF ELIMINATION METHODS

Elimination methods provide several advantages to race organizers – which we will see below. But elimination methods also have a clear appeal to the competitively-oriented mind of most humans. With elimination methods, since heats eliminate (or contribute to the elimination of) entrants, every heat is extremely important to the cars being raced. The audience tends to follow the event very closely to see which cars will prevail, and which will be eliminated (a bit like the gladiator events in the Roman Coliseum). This also has a down-side which will be discussed later.

Regardless of the audience appeal, here are three advantages of elimination methods to the race organizer:

1. Easy to Stage – Several methods exist for staging elimination races either manually or with a computer. The methods are generally easy to implement, thus minimizing pre-race effort.

2. Shorter Event Time – With an elimination method, the total number of heats is generally less than with a rotational method. Therefore, with efficient race staging, the overall length of the event can be shorter.

3. Facilitates Human Judging – While electronic finish lines are very valuable, races can be reasonably staged with human judges since only first place (or possibly first and second place) in each heat must be
determined.

DISADVANTAGES OF ELIMINATION METHODS

However, there are several disadvantages to elimination methods:

1. Lane Bias – No track has lanes which are exactly the same; generally one lane will be the fastest and another the slowest. Cars which, by the luck of the draw, are placed on the slow track will be disadvantaged. A car racing on the slow lane can be eliminated even though it is faster than the car on the fast lane.

2. Low Accuracy Beyond First and Second – By definition, a single-elimination race can only accurately determine first place; double-elimination determines first and second place; triple-elimination the top three places. Why is this? Consider the fastest three cars in a double-elimination race. If the top three cars race together early, then the second and third-fastest cars will be moved to the loser’s bracket. If they then race each other again before the final heats, the third fastest car will be eliminated. Some other car will (in error) win the third place trophy.

Thus, if your organization runs a double-elimination and wishes to give out three speed trophies, additional racing must occur to determine third place (see IMPROVEMENTS for methods to allow three trophy winners with a double-elimination race).

3. Crowd Control – As cars are eliminated, owners of the eliminated cars tend to get bored, resulting in crowd control issues. By the way, this applies to both kids and their parents!

4. Minimal Race Time – Similarly, when a child and their parent spend significant time building a car, they would like the opportunity to see their car race as many times as possible. But with elimination methods, the slowest cars will only (officially) race two times. This can certainly be a downer.

IMPROVEMENTS

How can improvements be made to address some of the disadvantages of elimination methods? The following are some ideas for you to consider.

1. Lane Bias – First, recognize that lanes are not equal. Therefore, make sure that Race officials don’t select which cars are placed on which lanes. When using a race chart, identify the lanes on the chart, and place cars into the chart using a randomization process, such as drawing car numbers out of a box. If you don’t use a race chart, but instead dynamically select lanes, randomize lane assign by drawing lane numbers. While this does not eliminate the problem with the lanes, it does eliminate any question as to whether an official was biased towards or against certain cars.

2. Low Accuracy Beyond First and Second – When using a double-elimination method, ensure that third place is awarded fairly by doing one of the following:

– After all heats have been run and first and second places have been determined, rerun all of the other cars to determine third. This method is not very exciting.

– Assuming you have a track of three or more lanes, in each heat keep the top two cars as ‘winners’, and the other car(s) as losers. Continue this process until only four cars remain. Eliminate one car. The remaining three are the trophy winners. Eliminate one more car – this is third place. Then race the two remaining cars to identify first and second place.

3. Crowd Control – To maintain interest, defer racing of the loser’s bracket for as long as possible. If you are using a race chart, try completing the winners bracket before running the loser’s bracket. If a chart is not used, then alternate back and forth, winners to losers, to keep everything in synch.

Another idea is to split the total group into several smaller groupings, then race the smaller groupings. Provide alternate activities for the groups which are not racing. If desired, the top finishers in each group can be raced to determine an overall winner.

4. Minimal Race Time – This cannot be completely resolved with elimination methods, but for small groups consider running a deeper elimination (e.g., triple or quadruple). For larger groups, provide a second track for ad hoc racing of eliminated cars (oftentimes the kids just want to race – they are less concerned about winning than the parents).

CONCLUSION

Improving the fairness of pinewood derby events is certainly an important consideration for the race officials. I encourage you to do take the extra effort to review your race method and make improvements
wherever necessary to increase the fairness and fun for all participants.

From Pinewood Derby Times Volume 3, Issue 7

To subscribe to this free e-newsletter, please visit:
www.maximum-velocity.com/subscribe.htm

(C)2011, Maximum Velocity, Inc. All rights reserved.
www.maximum-velocity.com

Pinewood Derby Car Showcase – March 13, 2012

Cars with a military theme:

Tiger Tank – Randy Britt

My son Cameron wanted to do a tank this year, and although it was challenging to stay under 5 ounces, we used balsa, lots of hollowing and cut down extra wheels to allow us to add 2.5 ounces to the rear. My son just missed a speed trophy, but was a unanimous design winner. A magnet turret mount allowed it to swivel and not fly off during the
race.

Chinook Helicopter – Ray Betts


This Army Chinook Helicopter took 1st place in the open race in 2010. It used a standard block, corn-dog sticks for the propellers, dowel rods for the fuel tanks and engines. Scrap wood was used for the propeller housing and a coffee stir stick for the drive line between engines.

LAV-25 – Matt & Joshua Jackson

Attached are pictures of my son’s recent pinewood derby build. It is modeled after the Marine Corps LAV-25 Piranha Light Armored Amphibious Vehicle. It should have 8 wheels but two were removed to meet weight. You can still see the holes for the other wheels, which can be put back on. The main feature of the vehicle is that it has working headlights and taillights that can be turned on and off via a switch in the back. The spare tire in the back houses the battery for the electronics which are inside the car. It also has a working turret with a blinking red LED inside to simulate firing. It was a total hit at our pack races a couple weeks ago. It’s not the fastest car but by far the coolest car he’s built to date.

The Anchor – Jason Sasser

My son and I built this car for our adult race. It raced like an anchor, pretty slow but won best in design. I am active duty Navy and most of the Pack is made up of Marines. They didn’t really appreciate my car!

From Pinewood Derby Times Volume 11, Issue 12

To subscribe to this free e-newsletter, please visit:
www.maximum-velocity.com/subscribe.htm

(C)2011, Maximum Velocity, Inc. All rights reserved.
www.maximum-velocity.com

The Pinewood Derby Bling-Mobile

By Susie Boyce

My son brought his pinewood derby flier home from Cub Scouts exactly two weeks before the race. My first instinct was to throw it away and cross my fingers that my husband would never find out. Having lived through previous derbies, I wasn’t sure I was prepared for another one.

Weighing our marriage in the balance, however, I decided to disclose the race information. My husband furrowed his brow, grumbled something about short notice and got right to work.

With some trepidation, I will divulge what happened next.

The following instructions and warnings could either be used as pinewood derby navigation tools for families or simply as a pinewood derby cautionary tale.

Either way, I hope they prove helpful.

THE DESIGN

Your Cub Scout is free to choose any design he wants. That is, providing the design he wants has been pre-screened for outstanding aerodynamic qualities by Dad. Dad must then spend a minimum of one entire Saturday in the garage cutting, sanding, painting and spinning wheels.

Both his and the car’s.

The Cub is welcome to help but may also disappear for long periods of time to ride his Ripstick, play with friends or get a snack – all without Dad necessarily noticing his absence.

PAINTING AND ACCESSORIZING

A trip to the craft store is essential. Since the aesthetic fate of the car hinges on this trip, Dad should think twice before inviting Teenage Sister along. Should this error in judgment occur, however, keep in mind that the final product may well be a race car with a startling amount of bling. It could even end up ornamented with sparkly silver weights, a dozen or so gems (the tiara kind) and an ever-so-swirly letter “S”.

Blinded by Teenage Sister’s zeal for the car’s breathtaking design, your Cub might temporarily forget that a pinewood derby car festooned by sparkly stuff isn’t necessarily manly.

THE WEIGH-IN

On the eve of the race, Dad will be unavailable, so Mom must accompany her son to have his car weighed. Once the car is found to exceed the maximum 5 ounce limit – which Dad had sworn would not happen – Mom should use the provided drill to make holes in the bottom of the car in an attempt to remove the surplus weight.

After several holes fail to do the trick, Mom will need to get more aggressive with the drill. This is a risky strategy, of course, because she might drill all the way through to the top of the car.

Should this unfortunate event occur, Mom can simply remove a gem from another area of the car and place it over the offending hole. In doing so, she will find that removal of gems doesn’t damage paint, which will give her another idea for shedding weight: taking off more gems.

If the scale still refuses to budge, Mom is allowed to mumble mild curses (under her breath only, kids will be present) while she drills more and more and more holes with the minuscule drill bit.

When approximately half of the car’s wood has been removed and its underside appears to have been caught in a crossfire of tiny bullets, the car will finally weigh in at precisely 5 ounces.

Later that evening, upon describing the problematic weigh-in ordeal to Dad, Mom should be prepared for the look of alarm on his face as he asks, “Did you drill the holes symmetrically? The car has to be balanced!”

Mom is permitted to react with passion, and not the kind Dad dreams about.

THE RACE

Mom will drag all her kids to the derby without Dad, who will be running late. It is imperative that she disguise her reaction upon seeing her son’s blindingly sparkly vehicle in the lineup alongside red, black and yellow cars boasting serious stripes and fire bursts of the traditional race car variety.

Just as the announcing begins and while Mom is trying to keep her 3-year-old from dismantling the track, she should expect her cell phone to ring and hear Dad’s panicked voice hollering, “Have you put graphite on the axles? You have to graphite the axles before the race!”

Moderate cursing from Mom is expected at this point, although she should try to keep it under wraps as much as possible.

Mom must speedily fish the graphite from her purse, toss it to Teenage Sister, yell across the gym for her to help graphite the wheels, continue to restrain her 3-year-old, and finally breathe as her son’s car comes in second place in the first heat.

At which point Dad will sprint in to take charge for the balance of the evening.

THE RESULTS

Despite the aforementioned stellar efforts of so many, the car will not place. It will, however, receive the distinction of being named “Weirdest Car” at the derby. As parents, try not to hold a grudge against members of the award title-writing committee. They certainly wouldn’t have seen this one coming.

THE TAKE-AWAY

Weighing his marriage in the balance, Dad must be careful to never say this out loud.

Ever.

But he will be inclined to blame the car’s losing status on all those holes riddling its undercarriage.

They were simply not drilled symmetrically.

Used by Permission

ABOUT THE AUTHOR

Susie Boyce and her husband have “successfully” navigated six Pinewood Derbies and have three more to go. Her column, “Momsensical,” is featured in several North Dallas area newspaper. Visit her web site at: www.seriousmomsense.com

From Pinewood Derby Times Volume 11, Issue 12

To subscribe to this free e-newsletter, please visit:
www.maximum-velocity.com/subscribe.htm

(C)2011, Maximum Velocity, Inc. All rights reserved.
www.maximum-velocity.com

Pinewood Derby Memory – Speed Prayer

We were having our Royal Rangers Pinewood Derby at Roanoke Valley Cathedral of Praise and we held a Powder Puff race for the girls. One girl had a car that barely made it to the end of the track the first heat. The next time she was called to race her car she started toward the track but then knelt down, put her hands under her chin and prayed for just a few seconds. When she got up and started toward the track again she dropped her car. I was standing beside the Pastor and I told him, “That will really finish off her car now; it won’t even make it to the finish line.”

The girl picked up her car and put it on the track and when the cars were turned loose her car flew down the track beating the other three cars easily. The whole place let out a cheer so loud you would have thought the winning touchdown had just been scored in the Super Bowl! I looked over at the Pastor and said, “Well God just let me know He can, and still does answer prays fast!”

George Gobble
Roanoke, Virginia

From Pinewood Derby Times Volume 3, Issue 6

To subscribe to this free e-newsletter, please visit:
www.maximum-velocity.com/subscribe.htm

(C)2011, Maximum Velocity, Inc. All rights reserved.
www.maximum-velocity.com

Pinewood Derby Memory – Always Thinking Ahead

When I was a Webelos Den Leader the most anticipated event was always the pinewood derby. The Derby was run on a Friday, and the Sunday before was practice day – a day to fine tune and see how your car would perform.

One of the boys in our Den, Kyle, was the quite shy kind, but you could tell he was always thinking about how to improve. On practice day, Kyle and his dad spent the entire 3 hours tuning and adjusting their car. It performed well, completing the runs with good times. The last thing they did as they were leaving was to buy a new car kit.

Race day came around and Kyle showed up with a totally new car. Not the greatest paint job or the sleekest design, but it looked good. One of the other boys in the Den laughed at it because of the way it looked. His car apparently had been built entirely by his dad at the auto shop where he worked.

To make a long story short. The finals came down to Kyle and two other boys. Kyle come in third. The kid with the dad-built car wasn’t even in the top ten. His mom freaked out, and started checking times and saying something like, “This is wrong; how can a car that doesn’t even look good beat my son’s car!”

Kyle had never won anything in his life and this was the biggest thing to him. Talking to his dad later I asked why they changed cars at the last minute. He told me that Kyle had used the practice session to work out the bugs, and then spent the week working on the mechanics of a new car. He wasn’t that concerned with the looks.

Always thinking ahead. Kyle now works for a major auto maker doing design work.

Gary Marquardt
Ann Arbor, Michigan

From Pinewood Derby Times Volume 3, Issue 5

To subscribe to this free e-newsletter, please visit:
www.maximum-velocity.com/subscribe.htm

(C)2011, Maximum Velocity, Inc. All rights reserved.
www.maximum-velocity.com