Different Designs for Co2 Dragsters
-
-
Building Co2 dragsters can be a fun way to learn the basics of mass, drag, friction and velocity. These principles form the basis of nearly all varieties of engineering and mechanics, which is why those who develop a love of Co2 cars while young often go on to careers in those fields. There are innumerable theories behind Co2 dragster designs, some created on the computer and others perfected through real-world trial and error.
Single Rail Design
-
These "toothpick" cars are often the fastest in classes where there are no limits on weight or size. A single-rail car is meant to resemble a Top Fuel dragster, and carries low mass as its top design priority. While fast, single-rail dragsters are very fragile, and tend to rise to great heights on the race standings before disintegrating into splinters.
Additionally, most Co2 racing classes carry restrictions on minimum weight, which is where the single-rail's bad aerodynamics begin to work against it. The blunt leading edge of the single-rail's Co2 cartridge area creates a massive pocket of high pressure ahead and drag behind, slowing the car and raising lap times.
Dual Rail
-
The dual-rail design can utilize wheels that are either inside or outside of the frame rails, and is preferred over single-rails where there are minimum weight restrictions. Benefits of this design are low weight and higher strength; drawbacks are less-than-optimum aerodynamics and difficulty of manufacture. It's not so much that twin rail cars are hard to make, but it is hard to make them straight, symmetrical and balanced.
Shell Cars
-
Where they are allowed, "shell" cars are almost always the fastest possible design. Based on Land Speed Racing Jet cars (LSRJs), the shell car is exactly what it sounds like: a hollowed out shell with the wheels enclosed on the inside. This allows the designer complete freedom when it comes to making the car sleek and aerodynamic, without having to make concessions for the wheels, axles or Co2 cartridge.
When designing a shell car for optimal aerodynamics, the best approach is to forgo individual wheel pods and protrusions, and go for a completely "bullet shaped" outer shell. Although they do have a bit more frontal area than "pod" designs, bullet cars have longer and sleeker front slopes and fewer protrusions to trap high-pressure pockets. This design is almost universally favored by high-end builder and engineers where rules permit.
Boat Tails
-
Avoid blunt rear ends at all costs; squared-off hindquarters cause heavy rear turbulence, which increases drag. Instead, place the tallest point on your car at the front of where the Co2 cartridge will sit, and begin tapering the rear quarter of your body off from there in a process called "boat-tailing." Avoid sharp edges and angles of more than 30 to 35 degrees, as this will promote flow separation and increase drag. As always, use the thinnest and hardest possible wheels with copper bushings and graphite lubrication for decreased rolling resistance and friction.
-
