Friday, December 5, 2014

Stumped by STEM

MSR Wisperlite and STEM

Nothing is more humbling than trying to create a STEM lesson plan for 11 year old boys. My History degree reflects my appetite for consuming information, making logical connections, presenting a hypothesis followed by supporting arguments. So building a STEM lesson into a process is fine. But some of the science still escapes me.

My Audience has the Attention Span of an 11 Year Old

My son is part of Troop 404. I want to be a good Dad, and provide some input to their scouting skills with the ulterior motive of forcing a bit of STEM into the process. We covered the use of Cotton Balls and Vaseline as tinder to start a fire. 11 year-olds are fascinated by fire.
State Changes: Solid, Liquid, Gas
We never really reached deep into the science of the flint and steel - a standard tool for scouts. Some metals burn (oxidize) at room temperature. Scrapping minute balls of metal from the flint exposes more of their surface area to oxygen - which causes them to burn. That's the trick.

We did start the discussion of the state change of Vaseline from solid, to liquid to gas as it was wicked by the cotton then burned. But you know... 11 years old.

Science: Change of State, Wicking, Oxidation,
Technology: Various tools to create fire/sparks
Engineering: A one-handed steel and flint (engineering simplicity)
Math: How to calculate the optimum amount of Vaseline (fuel) for a cotton ball (wicking framework) for maximum burn time.

From Flaming Cotton Balls to the Wisperlite Stove

The Wisperlite stove has not changed much in 30 years. I can say this definitively because I own the 30 year old version. These stoves consume, burn, various types of liquid fuel. But something else is happening as the liquid fuel moves from the canister, through the stove and into the burner.  

In the video above - did you notice that the correct way to start this stove is to set it on fire? A few drops of fuel in the lower cup, a source of fire, ignites a big yellow flame, then it burns down into an intense blue flame that sounds like a miniature jet engine. It's not like lighting your stove, or a BBQ grill.

You Can't Skip Steps to Get to the Jet Engine.

Something Else is Happening

I sent an email to MSR to ask if they have a simple description of the process. Is it a wicking effect like the candle example above, or a venturi effect, or flash evaporation? Or, is it some combination of these processes?
Proof that Math is Hard.
You have seen flash evaporation...
but does this explain the Wisperlite?


I hope MSR will reply, so I can build out:
  • Purpose and Materials
  • Course Goals / Instruction Mode
  • Student Goals
  • Syllabus
  • Content / Arranged
  • Supplemental Materials / Activities
Next up: Tent Technology, Thermarest, Scope Reticles.

The graphics above are linked to their original sources on the web.

Thursday, November 13, 2014

Cotton Balls Vaseline and Fed Liquidity

Cotton Balls, Vaseline, and Fed Liquidity

I'm from the Jack Daniel's school of economics. That is, give me a couple shots of Jack and I'll tell you my thoughts about the economy. The key to my thought process is obtuse linking of examples (stay with me here).

Cotton Balls as Tinder

We hosted a cub scout meeting a couple weekends ago, and as host I decided to have a show and tell session to demonstrate the use of flint and steel and cotton balls as tinder to start a fire.

Adding Vaseline (a petroleum product) to the cotton ball creates a long lasting tinder. It is cheap, light-weight, water-resistant and lasts a long time. The cotton acts like a wick for the Vaseline, holding the flame while allowing the Vaseline to change from solid, to liquid to vapor, then burn. (Hey, that's all you get -- I'm an Jack Daniel's Economist. If you what physics, come back at closing time).

Here are links to the starters and to a couple videos showing how this all works.

Conducting basic research in the internet is always a unique journey of discovery. While watching video number 4300 or so, an interesting question came up:

What is the optimum about of Vaseline to add to a cotton ball?  

The test:
  1. Take a plain 100% cotton ball and light it (record the burn time).
  2. Add increasing amounts of Vaseline to the cotton ball and record the burn time.
    (Change the ratio of tinder/fuel from 0% to ~99%).
  3. Determine optimum amount of Vaseline to add to get the longest burn time.
Internet video #4300 - Revelation

Can you light 100% pure Vaseline?  No, not with a flint and steel, not with a match, not with a cigarette lighter... it just melts.

Economic Link - Cotton Balls, Vaseline, and Fed Liquidity

Where is all of the Fed Liquidity?

Quantitative Easing, billions and billions and trillions of dollars, has only generated a couple percent GDP growth. The entire point of QE was to provide liquidity - to support the balance sheets of the banks and stimulate economic growth. So what happened?

Super-saturated cotton balls (economic capability) and Vaseline (pent up liquidity).

In our previous experiment we showed that a cotton ball loaded with Vaseline will burn longer than a clean cotton ball. Too much Vaseline and it will not burn at all. It has to be a lot too much, but you can try it yourself.

Maybe the Fed has created a situation where they have provided so much liquidity (Vaseline) that the economy (cotton ball) simply can't function.

PhD, Jack Daniel's School of Economic Stuff.   

Sunday, November 9, 2014

2014 BMW 328i 1500 Mile Review

Finally Named the New BMW 328i.

Elle as in Elle Driver from Kill Bill.

The 2011 xDrive was Alex Forrest - a tempting, slightly wild seductress. Catherine Tramell (Basic Instinct) and Matilda Ratched (One Flew Over the Cockoo's Nest) were high on the list. 

We'll get to the reason for our selection a bit later. 
Click for larger image.

Previous Posts: 

2014 BMW 328i 1500 Mile Review

The Good

The fuel economy is phenomenal - up from Alex's 30 months average of 20.6 to nearly 26 mpg. On Friday we did a loop from Round Rock to Anderson (College Station) and back -- over 30 mpg. Acceleration is solid, turns are a bit soft, but well controlled, and braking is excellent. She pulls with gusto from the line, and a hard press on the accelerator will always deliver a bit more. I was worried about all of the shifting (horrific in Eco mode, tolerable in Comfort mode), but in Sport mode, Elle was in the right gear most of the time.     

The Bad

The only way to have fun is to drive in Sport mode or Manual, and to drive well over the speed limit. Not that I haven't tried, but Elle performs under normal conditions without complaint. It's almost tragic - her good manners (cool professionalism) belie her skill. 

The Ugly

The double-tap to turn off the accessories does not work well. ECO-mode makes politicians happy, but I can't imaging anyone else liking this feature.  The Auto-Stop Start (or AS/S) is rough on the restart. 

The Bottom Line

The 2014 BMW 328i is Elle, cold, efficient, professional. She is not the super hot, sultry Catherine, or the super-controlling Nurse Ratched. Deep down inside you know she is trouble. 
“It's the first villain [Elle Driver] that I've played in a movie that has absolutely no vulnerability and no innocence, nothing whatsoever that is like-able about her, other than she's so bad. All the other Deadly Vipers have some empathetic quality: O-Ren Ishii has this horrible past, [Vernita Green] just wants to be a mom, the Bride has been abused, but my character is just bad all the way through, there's nothing to like about her, and you're going to hate her so much.”
Daryl Hannah (on Elle Driver) from the Kill Bill Wiki. 

The first road trip: Hwy 79, 6, 30, 21, 77, 112 - none of them posed the slightest challenge. Next weekend, a run to Stephenville (183, 281, maybe back on 36).

I just know that one day I'm going to do something, and Elle is going to pluck out my eye.

[Update 11/11]: We took an unexpected run to Cabela's - from Round Rock to Buda via Toll 130. The toll road has a speed limit of 80, so I anticipated some exciting driving. Well, not so much. I would actually slow down behind a truck, down to 65-70 MPH, then pass them. But, it was decidedly effortless (sigh). Elle was loafing along, just over 2000 RPM. I finally turned on the cruise control - which is a HUGE improvement over the '11 version. 


Friday, October 17, 2014

2014 BMW 328i First 500 Miles

2014 BMW 328i First 500 Miles

The Good

My previous BMW 328ix (Alex) averaged just under 21 MPG over 27,000 miles. Not bad for an xDrive used for a boring commute from Woodinville, WA to Redmond, WA. Alex didn't get a lot of freeway miles, so performance was pretty solid. 

The new 2014 BMW 328 has averaged out at 24.5 MPG. I have been hot-rodding a bit, and Texas roads speeds are much higher (even in town). Gas prices in Round Rock (Austin, TX) have been under $3.00 for awhile and this morning they dropped below $2.70/gal for regular. The 17% increase in fuel economy is pretty nice.

Review: The First 100 Miles
Review: 2011 328i xDrive aka Alex

Driving in Sport Mode is amazing.  

We took a short freeway run on IH-35 and the ride was scary. Scary, in that the BMW felt like it was doing 45... when we were (a bit) north of 70 MPH.

One of Alex's attributes was that she was not much fun to drive at 25 MPG, especially in parking lots and in crowded neighborhoods. At freeway speeds she was great, and at Texas Toll Road speeds (85 MPH) she was a joy to drive. Once the new plates arrive we're going to drive to San Antonio, and see if the new car can fly.

The Bad

ECO-Mode is still icky, although it is growing on me. Now that morning and evening temperatures have fallen, the reduced air-conditioning in ECO-Mode is more tolerable. Acceleration is non-existent, gear shifts are frequent, and the ride is econo-car. But, picking up the kids at school and driving through the neighborhood doesn't require more than a Corolla, and ECO-Mode effectively renders the 328i into a Corolla.

The Ugly AS/S

Texas uses flashing yellow lights to allow left turns. Roll out, pick your spot, accelerate, and you're on your way. The Auto-Start/Stop (AS/S) complicates this process alot. In addition to the calculation of on-coming car speed, and my ability to move through the turn, I now have to factor in AS/S. I've already worked on strategies to defeat it (shift to Sport mode, never come to a complete stop, lift the foot slightly off the brake). AS/S is very aggressive in ECO-Mode, so the calculation of Corolla like acceleration needs to be added to the momentary AS/S restart.

The Bottom Line

I denied the idea that  the new Turbo-4 couldn't compete with the inline-6.  I was angry that BMW would tinker with the engines, suspension, and drive characteristics that made Alex such a great ride. I struggled with keeping Alex... for days, trying to find a way to justify the purchase of an all-wheel drive 20MPG sedan in Texas.  

[Wikipedia Article]: K├╝bler-Ross model, or the five stages of grief, is a series of emotional stages experienced when faced with impending death or death of someone. The five stages are denial, anger, bargaining, depression and acceptance.

I'm finally coming out of depression, and into a reluctant acceptance that the new BMW (still unnamed) is a very different car, and is a good car.

Not a great car, yet... but you never forget your first.


P.S. Elle Driver, from Kill Bill is currently at the top of the list, although the lobotomizing Matilda Ratched, RN is still in the hunt (Maybe Elle in Sport mode and Matilda in Eco-Mode)?

Wednesday, October 1, 2014

2014 BMW 328i First 100 Miles

The First 100 Miles

Alex, my 2011 328i xDrive, the last of the straight-six models, went off lease last week (farewell review). I replaced her with a brand new 2014 328i, which is a very different driving experience. I drove Alex about 27750 miles which equates to ~1500 hours of time in motion. Most of the driving was in Woodinville and Redmond, WA at 30-45 miles per hour with very limited freeway time. 

I moved from WA to Round Rock, TX (just north of Austin) and found much better driving opportunities. Surface streets often run up to 60 MPH and the Toll Roads top out at 85. Alex didn't get many miles in TX, but they sure were fun. 

Now that I have had time to fiddle with the seat adjustments and the different driving modes, here are my first impressions of my new 2014 BMW 328i, RWD.  

I'm not convinced this one is "The Ultimate Driving Machine". 

The Good

Wow, the engine is responsive and actually pulls really well. Many reviews point to Turbo-lag, but pushing Alex from 1500 RPM to 4000 RPM also took some time. The steering is light and easy, and does firm up based on the driving mode. In Sport or Sport manual mode this is a great ride.

I had a loaner 328i (fully loaded) for a couple days in August. The run-flat tires and suspension setup were harsh, jarring, pugilistic. This new car doesn't seem to have the same setup. The ride is smooth, bumps are minimized, and the road is still very tangible. 95% of my 27750 miles were casual commute miles, not high-speed, racetrack oriented. 

I did not get any bling on this car. None. No lines, no exterior colors, no interior package, no Dynamic Handling, Cold Weather, Driver Assistance, Technology, or Premium package, no options or accessories. The only item listed on the window sticker was the 8-speed Steptronic. So, my car was a steal, a rock bottom priced BMW leading to a great lease. 

The Bad

8-Speeds means plenty of gear changes. In Comfort mode 4-5 gear changes take place driving in the neighborhood at speeds around 30 MPH. A good deal of work is going on between the engine, the computer, and and the transmission to get good mileage. Sport mode fixes this, but it seems like the jumps from Eco to Comfort to Sport are a bit wide. 

In Eco Mode I kept checking the floor to see if it was going to open so I could give her a push by going full retro Fred Flintstone. Sorry, I know the government is involved, and MPG figures must be met, but I suspect that ECO mode will be lightly used by all BMW drivers. Those frequent gear changes in Comfort evolve from noticeable to annoying in ECO where 2000 RPM is the shift point. I'll need a lot of convincing to see ECO as a feature. 

The Auto-Start/Stop (can I call it the ASS Function?) is also a bit of a work-in-progress. After measuring 20 something variables, including the price of tea in China, the AS/S function will decide whether to turn the engine off when you reach a full (and complete) stop. Don't try to out-guess the system, it knows what's best for you. 

Managing the interior temp to save gas, presents a bit of a problem. Sitting in the Texas sun (even in October) for a couple minutes will raise the interior temp just enough to re-start the engine. Defogging the windows (front or back) is also a hurdle for the AS/S. Essentially, the car is saying "I'm going to save a sip of gas and make you hot... deal with it". In Woodinville, WA., not an issue... in Round Rock, TX., fail. 

Yes, yes, yes, you can push a button to kill the feature, and heck, I have already learned how much relief to give the brake to get to a restart, but like the ECO mode, I'm not convinced that this is really useful. 

You know those Yellow-light must yield left-hand turn lanes? Confidence takes a hit when you are searching for a hole to jump through, and the AS/S decides to cut-off the engine. 

"Look Ma, I'm sitting in the middle of an intersection with my engine cut-off!" 

This is a pretty direct user experience, and a pretty poor experience. 

The Ugly 

The "Park" mode is a bit odd. The engine goes into "Ready" status, just like in AS/S. And the iDrive and accessory plugs remain active. Had the weird experience of having the car restart while sitting in the parking lot at CVS. My foot was on the brake, so the behavior was not "wrong" it was just unexpected. My Garmin is plugged into the 12-volt power receptacle and doesn't seem to turn off at all. In Alex, you turn the car off and the accessories go off as well. 

The iDrive Multimedia functionality is also a bit off. I plugged in my USB drive with 617 songs, scrolled through the menu options to set to Random... and off I went. The next time the car started it started at song #1/617. Pushing the right arrow on the stereo would send it to a new random song. Park (for some unknown period of time) and it's back to song #1 again. Alex would keep remember the track, even if the USB drive was removed and later replaced. 

The delivery specialist told me that the first time I linked my phone to the 328i, it would download my address book. My phone is both work and personal, with 707 contact cards (I checked in Outlook). I am actually scared to sync the Bluetooth for fear of the mess. I just need eight (8) entries, one for each storage location on the dash, but there is just no simple way to get there. 

The Bottom Line

The new 328i is much more enjoyable for my standard driving experience, smoother, quicker, better mileage (Alex reported 20.5 MPG combined after 30 months of driving). Purists, those that think fast is the only answer, will probably not be happy. People that want options will have to juggle the various packages, lines, and accessories to find a suitable combination -- at an eye-popping price. Driving modes, AS/S, and other minor annoyances will probably get worked out over time. 

My lease expires in 36 months... which gives BMW time to figure it out. 


Sunday, September 28, 2014

2011 BMW 328i XDrive Review and Farewell

2011 328i xDrive at Mt Rainier.
(Click for larger image) 

2011 BMW 328i xDrive "Alex" 

None of my previous cars ever had a name. But this BMW 328ix was Alex. She was Alex from day one, and she gained nothing but admiration, all the way from mile 20 through mile 27750 when her lease expired.

Alex didn't need jewelry.  No navigation, no upgraded stereo, no fancy seating surfaces, or special colors, or sunroof. She had  6-speed Steptronic, xDrive and heated front seats.

The Good - BMW xDrive

The xDrive system was amazing. Driving around Woodinville (Seattle), Washington was always a mix of damp, moist, wet, rainy, wet, rainy roads. Sometimes there was a bit of snow and ice. Never once was I concerned about how Alex was going to handle the conditions. Even when I tried to force her to do bad things, she stayed stable and composed. The anti-lock brakes were a big part of this behavior. Bottom Line: I could drive well past my skill level and Alex would provide huge helpings of semi-crazed fun.

Every minute over 60 MPH was a joy. When we relocated to Texas my first trip was from Round Rock to San Marco on Toll Road 130. I'm sorry, but under 50 MPH the 328ix is just loafing around. Many surface roads in Texas are 50+ and the toll roads run as high as 85. In WA I don't think the run-flat tires ever reached a good operating temp. In TX, with outside temps at 100 and road temps much higher, the tires got warm, got grip, and softened up to a smooth ride.

My recommendation, get a set of Texas Tags, get a full tank of gas, and jump on the toll road - American mini-Autobahn. It's actually quite eerie how Alex would settle down into a purr at 70, then growl and run to 85+.

Black on black, xDrive, and heated front seats = low cost. My MSFT employee discount helped. $3000 down and $309 for 30 months, 10,000 annual miles. I'm not sure why anyone would pay hundred of dollars more for special paint or a sunroof, or bling.

Alex did go to the shop twice, once for a problem with the alarm system (it was buzzing, and required a quick reset), and once to replace the door gaskets. The rubber failed (split) and was replaced under warranty.

The Bad - Wide Turning Radius

Alex hated parking lots, and turning around (turning radius was just short of the Titanic), and driving slow. And, her paint was very susceptible to scratches. You couldn't park far enough away from the dilweeds that would ding the doors. BMW needs to build a force field and add tazers to their future models.

The Ugly - I will not be ignored, Dan

Alex's full name was Alex Forrest, named after the Glenn Close character in Fatal Attraction (IMBD Link).
Happily married New York lawyer Dan Callagher has an affair with his colleague Alex, and the two enjoy a love weekend while Dan's wife and kid are away. But Alex will not let go of him, and she will stop at nothing to have him for herself. Just how far will she go to get what she wants?
My previous rides had been Volkswagens (Scirroco, Rabbit GTI, Jetta, Jetta GLX, Passat, Jetta Sportwagen). You know, the perfectly respectable Anne Archer type car. Alex was my mid-life crisis, my hot, slightly-crazy fling. She made sure to set her claws deep.

This week my 30 month lease finally expired (has it really been three years, it seems like a couple of weeks.). Alex was returned to Austin BWM. I have a new 328i, a saucy, quick steering tart (unnamed so far). It feels exactly like 1978, when my girlfriend (GMF) graduated high school one year ahead of me, went off to college, and we had to break up. Who knows what would have happened... cue slow motion heart-break and life-long regret.

Someone in Austin is going to get a great car. The xDrive is not common (Austin BMW has 24 used 328i models in inventory, and only Alex is a 328ix). The xDrive does not get the price premium that it does in WA. Maybe one of you Colorado snow-birds will take a look.

Her name is Alex, treat her nice, or treat her a bit rough, she will make you hers.


Tuesday, March 4, 2014

Putin, Obama, Dark City, and Rat Experimentation

Dark City (1998)

The best Dark City (IMDB) review is from Roger Ebert ( Ebert goes on and on about the visual content, the blending of genre and the visceral feel of the movie.

Small Spoiler Alert (will not ruin the movie)

Dark City uses midnight as a timing element for re-staging reality. In an early scene the doctor is running rats through a maze in what appears a typical experiment. The maze is set on a round table, and the doctor has a prod to encourage the rat. 

This construct serves as the larger metaphor for the movie, where humans are trapped in a city-sized maze. Each night at midnight the maze is reset, the test conditions reset and the test subjects are reset. John Murdoch breaks the pattern... and (I'll  not spoil the ending).

US Rat Experimentation (Foreign and Domestic) 

"As he [Putin] put it, the US has interfered in Ukraine “from across the pond in America as if they were sitting in a laboratory and running experiments on rats, without any understanding of the consequences." (Forbes, 3/4/2014)

While I might digress to say that the Administration is testing rats domestically as well (that would be you and me), let's stick with the foreign angle. 

What does Putin see? 

When President Obama drew and then erased the red line in Syria, Putin was watching. Juan Williams may be technically correct arguing that President Obama did not have congressional backing to go to Syria. Williams' clear omission is that Obama did not have the political capital (even in his own ranks) to draw the red line in the first place. 

When we claimed we would get out of Afghanistan and Guantanamo, and ignored Egypt, Syria, Venezuela (etc.), Putin watched. The disaster at Benghazi.  Weaponizing the IRS against the opposition. The Obamacare launch - total fail, with so much "fine tuning" going on that it is hard to know what's really real. We dithered on Keystone, and are now talking about reducing our military. Remember the US bid for the Olympics? 

Putin sees plenty of talk, plenty of bluster, plenty of complaining, and plenty of retreat. He sees a US Administration that is OK with failure, willing to create excuses and diversions. He sees the mistake of thinking that Obama's persona will carry the day. 

Putin is not a Mad Scientist

The Strangers in Dark City were searching for something specific... the human soul. Is mankind nature, or nurture, a collection of our memories, a collection of our collective memories, can you change the true nature of a person by changing his memories, or his environment? They need to understand how our soul works in order to save their race. 

Putin is not searching for something intangible like the human soul. As Romney and Palin clearly presaged, Putin is ACTING to get what he wants. Whether it is Georgia or Ukraine, Putin is acting to expand Russian dominance. Proof? How about a couple of maps showing oil pipelines in Ukraine and a detailed discussion of pipelines through Syria

I  still wonder what George Bush saw when he looked into Putin's eyes. 

Putin does not care about our soul. The current administration is too busy experimenting with social justice to care about our soul.

We need to care. 

Monday, January 20, 2014

Pine Wood Derby Results - Mea Culpa

Pine Wood Derby Results - Mea Culpa

After my previous post about the challenges of building "Blue Steel" for Tot3, the results are in:

Overall Standings (Pack 5 Round 1 & Round 2)
Den Time  Car Name    Speed (MPH/Scale)
5   9.122 Blue Steel    213.03
1   9.208 Day & Night   211.12

So yes, we kicked butt (by .086 of a second), took names (the second place finisher won the derby last year), and spiked the ball (but not in a mean, Seattle Seahawks' Sherman way). 

As for Tot3, her car had a devastating weight blow-out in her second run. Apparently, the heat generated by pine wood derby cars can melt hot glue. We were able to fix the problem (duct tape, of course), but Ender started .05 oz light, and losing a quarter (.02 more) meant a disappointing 60th place finish - out of 75 entrants. Ender clocked in at 194.96 over 4 heats.

Of course, next year is going to be a challenge.

Friday, January 17, 2014

The Boy isn't Going to Win, and other Pinewood Debry Musings

The Boy isn't Going to Win, and other Pinewood Debry Musings

Preparing for Defeat

This weekend Pack 552 is holding their annual pinewood derby. Last year the results were devastating. The winning cars clocked in at ~220 mph in scale speed. Tot4's car ran under 180 on all four heats. He was not happy with the results, and we are still trying to figure out where he gets his hyper-competitive streak.

New Strategy  

For Christmas we gave the boy a copy of "Building the Fastest Pinewood Derby Car: Speed Secrets for Crossing the Finish Line First!" The book has 10- 5-star reviews on Amazon, but wow, no way. 

While it is technically possible to follow all the rules, it is unlikely that the average Dad (that includes me) could execute all of the rules. The high tech design offered by the author requires very skilled execution with a variety of very specific tools and techniques. As a Project Manager that leads teams to build data centers, I lack nearly all of those skills. 

Rather than describe how the first car body was destroyed (while manually drilling the rear of the car to insert 3oz weights), I'm going to talk about the things that did work and that didn't require micrometers or feeler gauges. Yes, both are encouraged by the book.

First - Keep the body shape simple and leave room for adding weights.

Band saw experts can cut beautiful curves, sweeping, swooping, dipping, bending body lines. But the cars that won last year were basic wedges - low, and shaped at the front, then rising slightly above the rear wheels. We employed this style for Tot3 - she will be in the sibling / wildcat class and will likely have great speeds for a very simple design. 

Second - Spend a bit of time on the axles and wheels.

In this case the book gives a couple of key tips about proper grinding, sanding and adding a slight back-angle to the head of the axle. I simply inserted each axle into a hand-drill and used a small file and scrap sandpaper to smooth out the burrs and polish the shaft. 

The head of the axle needs to be filed slightly out, away from the shaft, to reduce contact with the wheel. (I refuse to quote microns or degrees like the book does, besides I need a few trade secrets). Rolling the axles on a flat smooth surface did a pretty good job of identifying the "top" of each axle. Both cars were tested to see if they rolled straight. 

Applying weights to the body can be a tough call. The key is maximizing "potential" energy by mounting the weights in specific locations. Somewhere out there is a physicist that will describe that location... he was probably the dad of the author of the book. 

Best Tip from the Book

Probably the best tip in the entire book was the method to correct the problem when the car pulls to one side or the other (buy the book, or send me a note). The second best was to use graphite in the axles. The wheels were able to spin much smoother with graphite. The test is easy: spin the wheel with your finger and listen to the friction. Add graphite, repeat. Quieter = better = faster. 

Worst Tip from the Book

Use a drill press and drill holes into the back of the car leaving enough clearance for the axles... 0.00125" clearance... check with micrometer, perfectly horizontal and parallel... "My God Jim, I'm just a country doctor."

Best Tip from Me: 

Krylon filler/primer - about $5 from Lowe's. You can spend a lot of time sanding your car, but this Krylon product fills most of the pores, sands in about 30 seconds, and takes a beautiful coat of color. Tape off the slot for the axles, spray, dry, sand... spray on final coat... perfection.

Boy's car from Mars, "Blue Steel" 

For the boy, weights were placed above the rear axle - and the weights became part of the body design. A wedge shaped weight covers a hidden, slide-in weight. At the weigh-in we simply slide out the lower weight, clipped off .2 ounces of excess weight and he was ready to go. (Did in mention that we had to cut a slot to hold the sliding weight, and that the top weight had screws just slightly larger than eyeglass hinge screws, and that I have hands the size of a gorilla? And, he wanted two tone paint with silver pinstripe and reflective metal canopy? And, that he expects to WIN)? 

Girl's car from Venus, "Ender"

For the girl, a simple wedge shape with secondary cuts on the nose for aerodynamics and the weights were added under the car, directly in front of the rear axle. Drilled 2 - 1 inch holes on the center-line, and added quarters for weights and a spot of glue from a hot glue gun to hold them in. We left the car slightly light, took, quarters, nickles and dimes and the glue gun to the weigh-in. Checked the weight, added a quarter (11 total) and hit it with a spot of glue - 4.95 ounces. She had a two-tone paint job and decals and the final clear coat destroyed an otherwise simple paint job. 


Both cars will do well on speed, and both are pretty good looking. His car took about 10 hours of hands-on effort, hers about 5. She has a good chance of winning the sibling wildcat class - which tend to be cars submitted for style awards. He is racing against 80 other boys. Applying the Billy Ball (Moneyball) principle, she is going to get the most production (success) for the effort (cost) applied. 

A Note to other Dads (and Moms)

The Boy Scouts promote participation and having fun. That does not apply to the Pinewood Derby. Other Fathers (and some Moms) see this as a core line item for college entrance applications. Kids from these parents grow up to write books on how to make your car fast. Winners get to spike the ball and do their touchdown dance. 

Both of my kids were encouraged (OK, forced) to be present when I was working on the cars. We talked about the process, what worked, what wasn't going to work, what was going to be hard to do. They got to help on tasks that they could manage.  

You can see the Pinewood Derby as a contest, or as a great chance to spend time with your kids. 

I'm going with the latter. 

...unless we win.