Space for various parts in race cars is increasingly limited. One approach Moto3 racing is using is to use flexible parts that can bend when certain driving conditions arise. The company’s design team worked with CRP Technology’s R&D department to create flexible cooling ducts and wiring harnesses using selective laser sintering and Windform materials.

Together, the two groups tackled the development of a front air inlet that would solve space issues in the front fork area.

Testing showed that increasing air flow to the air-box improved the performance of the engine at every speed range. This led the team and the engineers to conclude that they needed to design a new track-ready inlet. The design would make the air inlet longer, and bring the opening up to the front side of the fairing to have a direct air flow with less turbulence.

The constraints were that they could not modify the existing frame and existing triple clamps. The design would have to fit to the current platform to test the on-track advantages and disadvantages of using this solution, and to make a direct comparison with the current standard inlet.

The use of selective laser sintering and Windform materials allowed for:

-Total freedom and no limitations in design (Design For Functionality instead of Design for Manufacturing)

-Creation of a mock-up for assembling, fitting, and functionality

-Production of parts for performance tests

-Reduction in product and project realization timing

Through reverse engineering, the original airbox was scanned and virtually assembled with the CAD system. Then the engineers created a new model of the air inlet by taking into account the amount of available space, and the constraints of the assembly of the current airbox and frame.

Then a prototype using Windform GF 2.0 material was created. The decision to use this material was made to reduce costs while allowing multiple tests with multiple prototypes.

With the first prototype, the engineers checked if the design fitment was correct and suitable for assembly. The first design revealed that some sections needed to be changed due to the lack of space available under the lower triple clamp. The problem was further complicated when the bike was cornering and under braking conditions.

To optimize the volume of the inlet duct under the lower triple clamp, the engineers adopted a creative approach and used a portion of the duct in Windform RL, the new rubber-like composite material. This would be bonded to the main structure made out of Windform XT 2.0 for evaluation in racing conditions. The team also carried out a bonding test to study the characteristics of the final assembly.

The idea was to make the bottom part of the duct with Windform RL in the fork and triple clamp area, and then assemble this into the top part produced in Windform XT 2.0. This approach would allow good clear airflow on the straightaway sections of the course, and excellent flow to the airbox. Under breaking, the front fender could move up and collapse the inlet duct without any damage due to the flexible material.

After examining the part making the ducting flexible in the same area next to the front forks, the engineers could maximize the duct volume because the maximum steering actions are only reached when the bike is pushed into the paddock by the technical staff. In this situation, the front fork can touch the inlet duct deforming it without damage.

A second prototype was made in Windform GF 2.0. Once it was mounded the engineers noticed some changes needed, especially in the front fork area.

The soft section was too short and the forks could touch the area of the duct near the bonding overlap when steering travel was checked from lock to lock position. It was also seen that toward the back of the flexible area, near the airbox, that the duct was very close to the front wheel in the maximum braking position.

During testing it was determined that when the motorcycle was under severe braking, the front fender contact area on the duct in the soft part was too large. This situation, from the rider’s point of view, was not good because during hard braking, the steering must be free from movements, as the rider might need to correct the trajectory quickly.

The amount of input from the rider may be small, but it must occur smoothly, and too much contact of the front wheel assembly gave the impression of drag on steering. This affected the feel of the bike for the rider.

The engineers decided to change the inlet by reducing the portion that would make contact with the fender to reduce drag perceived by the rider.

The part made in Windform RL was enlarged according to the second test, and engineers and the rest of the team could get the correct fit for performance.

In the final test version, Windform XT 2.0 was used to reduce the weight of the front and central part of the inlet, while Windform RL RL material was used for the flexible part of the inlet. The two parts were bonded together after being produced.

CRP Technology
www.crptechnology.com