How Do Scale Calculations Affect RC Car Physics?

[DKTKD]

Hello All,

I'm doing some fun at home experiments with my 1:6 scale RC car and I
wanted do some camparisons with its full scale counter part.
Mainly how jumping the two off a ramp (Duke's of Hazzard style).

I wanted to know if you can help me with confirming some of my scaling assumptions for mass, force etc.

1. Acceleration,velocity and distance:straight 1/6 scale.

2. Mass: I would like to add weight to the RC to scale the mass.
Since mass' relationship to density (p=m/v), the scale weight
would be 1/216 (1/6 ^3)of the full size car.

3. Force: Now the force required for the scaled mass to the achieve the scaled acceleration would be 1/1296 (1/6 ^ 4) scale of the original force.

4. Projectile motion (w/o drag): With the scaled veloctiy/accel i believe the
horizontal component will properly scale. However I don't believe the
calculations for the veritcal component will scale correctly, because the
hang time will not scale. This being that I can not scale gravity.

Since the hang time will not scale, this would effect the range
the scale model will travel in comparison to the full scale.

Is this correct? Is there a work around for this?

Thanks
RC Guy

 

[Mindscrape]

Acc, vel, and position could potentially vary as more than 1/6, and position will certainly not factor as 1/6 because it will be at least be quadratic.

For the most part though, your approximations will probably work.

 

[m2003]

I can help confirm your scaling assumptions for the mass and force of your 1:6 scale RC car. Your calculations for mass and force appear to be correct based on the relationship between mass and density. However, I would caution against assuming that the scaled velocity and acceleration will be exactly proportional to the full size car. There may be other factors, such as the materials used and the design of the RC car, that could affect its performance.

Regarding the projectile motion, you are correct in that the hang time will not scale properly due to the inability to scale gravity. This means that the range of the scaled model will not be comparable to the full scale car. As a workaround, you could try adjusting the angle of the ramp to see if that affects the range. Additionally, you could also try using different materials for the ramp to see if that has an impact on the hang time. I would also suggest conducting multiple trials to account for any variability in the results.

Overall, it's great that you are conducting these experiments and making scaling calculations. However, it's important to keep in mind that there may be other factors at play that could affect the results. It's always a good idea to conduct multiple trials and make comparisons to ensure accuracy. Good luck with your experiments!