What Would You Try with These Wildly Permissive Rules?

[KineticPotential]

My son's pack and district have a peculiar set of a rules that ban certain widely used techniques, while still leaving the door open for some creative designs. Many common practices like 3-wheeling and altering the wheelbase are prohibited. Oil, washers, bushings, and bearings are also banned. However, there are very few other restrictions. For example, there are no prohibitions against sticky noses, springs, or moving parts! Weight must be permanently attached, but nothing prohibits moving parts or weights that remain attached. "Mercury tubes or other high-tech devices" are also banned, but the "high-tech devices" provision seems so vague as to be potentially useless.

Even the Open Division rules are extremely liberal: literally anything that fits on the track!

What would you consider trying with rules like this? We are considering building two cars next year: one "advanced" car to exploit as many loopholes as possible, and a "standard" car, which we will race if the advanced car is disqualified. I'm a mechanical engineer, and I have some crazy ideas of my own, but I'm curious to see what this group will come up with!

 

[Loud2ns]

It's kind of hard to give an accurate suggestion without the actual rules.

 

[Brian Stanley]

If the rules prohibit 3 wheeling and changing the wheelbase then whatever more exotic things you can come up with will likely be deemed outside of the rules by the race officials.

 

[T-Bone Racing]

Like Loud2ns said, it’s hard to say what is best without knowing the exact rules. The only suggestions I have would be to work on prepping your wheels and axles, put your weight in the back of the car, and keep the car to a quarter inch if that is the design you are looking for. If your rules allow you to bend an axle for steering, that would be beneficial because you can build a rail rider. But if you can, like Loud2ns said, let us know the rules so we can help out more.

 

[Jupiter 2.9]

Check your rule set for what is allowed in the wheel & axle department.
Axles & super light wheels can gain a car length or more, “If they are allowed”
Good polish & prep is a must no matter what the rules are. The videos are on this site somewhere.
I wouldn’t try to out smart anyone just out prep them, even with stock parts.

 

[KineticPotential]

It's kind of hard to give an accurate suggestion without the actual rules.

Full rules:

1. The Cub must race the same car he raced in his Pack Derby

2. Width can't exceed 2 3/4 inches, length can't exceed 7 inches, and weight shall not exceed 5 ounces

3. All cars must be built from the official BSA kit. All functional parts (wheels, axles) must also be BSA official parts.

4. Axles must be inserted into precut grooves of the car body OR not exceed a wheelbase of 4-7/16 inches center to center unaltered.

5. Wheel bearings, washers, bushings and wheel coverings are prohibited.

6. Axles may be lubricated with powdered graphite or any BSA certified lubricant. (No liquid)

7. No wafering (sanding thinner) or tapering (slanting to run on one side) of the wheels is permitted. Wheels must remain flat with full tread surface. All wheels must contact the track.

8. All weights must be permanently attached to the car (do not allow the weight to project from the bottom of the car as this may cause the car to hang up on the center guide of the track).

9. Once the car is weighed in and placed in the pit, NO ALTERATIONS, WEIGHT CHANGES, REPAIRS OR LUBRICATION of the car will be allowed without the approval of the Race Chairman.

10. If a car breaks down during the race, it may be disqualified at the discretion of the Chairman.

11. If a car interferes with another the heat will be re-run.

12. If a car jumps the track and does not interfere with another car, the car receives last place for that heat.

13. Registration and weigh-in times are in this brochure. Weigh-in will only be permitted at specified times. BE ON TIME or be disqualified.

14. Scoring-Each car will race on each lane of the track. The top 3 will be determined by their race times. They will race each other in a final round.

15. The Pack Derby Chairman or Cubmaster WILL IMPOUND THE TOP TWO FINISHERS and alternates of the Pack Pinewood Derby. No alterations may be made to the car between the dates of the Pack Derby and the District Derby. These cars shall be in the possession of the Pack Derby Chairman or Cubmaster until the date of the District Derby, at which time they MUST BE turned into the District Derby Committee or Chairman. At this time the only alteration that is permitted is the application of dry graphite.

16. There will be no Mercury tubes or other high-tech devices put on or in the cars.

17. The boys who make it to the District Pinewood Derby SHOULD BE PRESENT AND IN UNIFORM at the Derby.

18. It will be the responsibility of the Cubmaster to see to it that all Cubs who participate in the District Derby comply with all National Pinewood Derby rules as well as all of the rules and regulations listed above. We recommend these rules be used in the individual Pack Derbies.

 

[KineticPotential]

I guess I didn't state the premise of my question very well. I'm not looking for tips to help us win. A well executed "normal" car should easily win our pack derby. (On a 42' Best track, the average time of the winner this year was 3.3029, so...) I'm more interested in the unconventional ideas you might try if you could get away with it.

I wouldn't race something outrageous against the scouts. To do so would be contrary to the spirit of the event, and in this case is also totally unnecessary to achieve a winning car. This is just an interesting thought experiment, to consider what one might try if springs, moving parts, etc. could be used.

 

[KineticPotential]

For example, here's one crazy idea:

On a regular flat body car, add a pivot point near the front and a long lever that runs the length of the car. It might look something like a catapult. A weight is attached to the free end of the lever. A relatively weak torsion spring applies a force to raise the lever. When the car is level, the spring does not have quite enough torque to overcome the opposite torque caused by weight, and the lever arm rests down on the top of the body. However, when the car is inclined (like on the starting ramp), the weight does not apply as much torque to the lever, and the spring has enough torque to rotate the lever into a more vertical position (a stop would be necessary to prevent the lever from rotating past vertical.) The car would have a higher COM on the ramp than on the flat, effectively raising the starting height on the car and giving the car greater potential energy.

I think it would probably work, perhaps not enough to overcome the aero and stability losses, and definitely not necessary to win here, but if the racing were more competitive, I'd be tempted to at least run some experiments.

 

[Loud2ns]

I'm more interested in the unconventional ideas you might try if you could get away with it.

I wouldn't race something outrageous against the scouts. To do so would be contrary to the spirit of the event, and in this case is also totally unnecessary to achieve a winning car. This is just an interesting thought experiment, to consider what one might try if springs, moving parts, etc. could be used.

I was given some advice in my rookie year. "Get fast using the methods and knowledge out there. Then start experimenting." I'm still not experimenting yet! Lol
I think you can build a pretty decent car even with that rule set.