CO 2 DRAGSTERS The Fast the Furious Your

CO 2 DRAGSTERS The Fast & the Furious

Your CO 2 dragster may be small, but it's going to be moving at incredible speeds when you race it. That means it will be subjected to a wide variety of forces that affect its motion and velocity. Here are some of the principal forces involved…

MASS Obviously, this is how large and heavy the car is. Simply put, the less weight your dragster has, the faster it will go. This is the most important factor that will figure into your design. Keep it light!

THRUST • Thrust: The gas escaping from the CO 2 cartridge in the car. Every cartridge has 8 oz. of CO 2 and will be released the same way.

FRICTION The second most important fact you'll face. Because the dragster has parts moving against one another, friction is created. You can help reduce it by making sure the axles are free to rotate, and that the wheels and tires are not rubbing on the car body.

DRAG Here's where aerodynamics come into play. As an object moves through the air, it is met with air resistance as speeds increase. This air resistance pushes against your CO 2 car and prevents it from going as fast as it could in a vacuum. You can't completely ever reduce drag, but you can help reduce it by building a more aerodynamic car, but those are more difficult to create.

In terms of physics, the rapidly escaping gas illustrates Newton's Third Law of Motion -- for every action there is an equal or opposite reaction. The rearward motion of the gas pushes the car forward in this case, overcoming inertia or the resistance to movement.

1. The Challenge: To design and build a CO 2 dragster that will go as fast as possible. 2. Brainstorm Ideas: shapes? Cuts? Sanding? Wheels? Ways to eliminate friction? 3. Best Idea: 4. Build: weight/cut/weight/sand/weight/paint/weigh 5. Test : launch #1: How did yours compare to others? 6. Modify: make faster! 7. Launch #2: Did you improve? 8. Final launch: Did you make the top 16?

What Your Teacher Will Do: • Make one top cut and one side cut to your dragster body. What YOU Will Do: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Trace the side and top view of your balsa blank onto paper. Mark where the axle holes will be and where the CO 2 hole is. Use a different color to draw your dragster shape. Is it the right length? Transfer your design to a dragster blank. Drill axle holes in the body while the car is flat. Have Mr. Johns cut the major cuts for you. Use sandpaper to finish shaping and smoothing your dragster. Paint your dragster. Add axles, wheels, and screw islets. Clearly paint or draw your ASSIGNED racing number on your dragster.

CO 2 Car Specifications For Official Competitions

Dragster Body • One (1)-piece, all-wood construction. Any type of lamination will result in disqualification. Two (2) or more like or unlike pieces of wood glued together are not considered one (1)-piece, all-wood construction. No addons such as body strengtheners, fenders, plastic canopy, exhausts, or air foils may be attached to or enclosed within the vehicle. Fiberglass and shrink wrap are considered body strengtheners and cannot be used on the car body for any reason. Decals may be used for decoration only. They may not be used to gain an aerodynamic advantage, i. e. , decals cannot cover the exterior axle holes or be used to cover open areas of the body.

Dragster Body Length • Min. 230 mm Max. 240 mm

Dragster Body Height with Wheels • Max. 75 mm

Dragster Body Mass (without Co 2) • Min. 35 g Max. 65 g

Weights of Parts • Standard back (large) wheel = 6 g • Standard front (small) wheel = 2 g • Standard axle = 4 g • Four standards front wheels and two axles = 12 g

Dragster Body Width at Axles Front & Back • Min. 35 mm - Max. 42 mm

Axle Hole Height 5 -10 mm

Wheelbase (Axle Distance at Farthest Points) 105 mm-222 mm • Min. 105 mm Max. 222 mm

Bearing, Bushing and Lubricants are Legal

Spacer Washer • Spacer Washer; Maximum: 10

Axle Clips • Axle Clips; Maximum 4 • (Used to hold axles in place for shell cars)

Power Plant Housing Thickness • Min. 3 mm

Chamber Diameter to Race Surface (with wheels) • Lowest point of chamber diameter to race surface (with wheels) Min. 26 mm Max. 40 mm 26 mm – 40 mm

Screw Eye Inside Diameter 3 -5 mm

Screw Eye Distance Apart 200 mm or more

Wheels • Four 30 mm-40 mm wheels are required. • Wheels may be inside our outside of the dragster. • Total width of dragster must be 90 mm or less.

Wheel Diameter • Min. 30 mm Max. 40 mm

Wheels Width 2 mm-18 mm • Min. 2 mm Max. 18 mm

CO 2 • CO 2 canisters must be Pitsco 8 oz. • CO 2 can be very dangerous or even deadly if treated improperly. • The most important measurement on your car is likely the “power plant housing thickness”. • The second most important safety detail is that both screw islets are secured. Use a drop of glue to secure them.

Strategic Ideas for Reducing Friction: • Put axles in a drill and use light grit sandpaper to clean and smooth them. • Put wheels in a wheel lathe. • Use a little graphic powder inside straw or bushings. Hand turn axles until the powder is as smooth as possible. • Use washers between wheels and body.

Strategic Ideas for Reducing Drag: • Put the wheels INSIDE the body. • To do this, you’ll need to hollow out the body. This is known as a SHELL CAR. • You will have to drill the wheels so that the axles go all the way through them. • Make your car as light as possible. (As close to 35 grams as possible). • Use an aerodynamic shape!

The Most Aerodynamic Shape?

Real Cars Close to a Teardrop Shape:

Concept Car with Teardrop Shape

Making a Truck More Aero

Is a Teardrop Dragster Possible? SIDE VIEW TOP VIEW

National Junior High Champions!

ST 1 PLACE

National High School Champions! th 10 Place

th 9 Place

th 8 Place

th 7 Place

th 6 Place

th 5 Place

4 th Place

rd 3 Place

nd 2 Place

Shell Car? Rail Car? Hybrid?

Bottom of Shell Car • Use scraping or carving tools to hollow out room for the wheels. • You could also use a large drill bit and drill it out. • Use axle clips to prevent the axles from slipping out.

2015 District CO 2 Championship Overall Points Winner: Les Bois Fastest Car: Les Bois

The belly of the beast

W a h l l i tw U YO u B ? ild