Project 4X: the development story by David Ehrbar



David Ehrbar, Serpent‘s designer explains the genesis of the “Project 4X”, a revolutionary 1/10th 4WD electric touring car:

The history of this project is long, and it is a history of my own passion for innovation falling on fertile ground when I presented my ideas to Serpent.

Some basic ideas were in my mind for a very long time. While I know the love to details is very important, especially regarding setups of 1/10th scale touring cars, I was convinced that modern touring cars with their concept are at their limit, and at some point, if you want to do further progress, you have to take a different route and show up with some true innovations.

In summer 2013 I decided that I finally want to work on a completely new, revolutionary car. I was inspired by fullscale racecars, and I wanted to have a system with decoupled roll and heave/pitch suspension as it can be found on some fullscale F1 cars, but basically also in the rear of RC-pancars (like F1, 1/12th).

So I came up with the idea of a classical pushrod suspension, which gives many freedoms in shock arrangement. You can build a car which has one spring and damper per wheel, or you can have a classical third spring arrangement where a third spring and damper supports the vertical movement of the car. Both were used a long time in many fullscale motorsport cars. In recent years, some F1 teams came up with the idea to completely eliminate the springs and dampers per wheel. Basically they relied on their previous 3rd spring as the sping for vertical movement, and the antirollbar for the roll movement of the car, and that was exactly what I wanted to have. Besides a certain weight advantage compared to a 3rd spring setup, this gives the possibility to tune the suspension for vertical movement (aero, bumps and accelerating/braking) and roll movement (cornering, curbs) completely independent.

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