CRP Technology has developed a new front air inlet for a Moto3 racing customer using WINDFORM materials and a selective laser sintering (SLS) additive manufacturing technique.
Modification to the existing frame and the existing triple clamps had to be avoided. The design would have to fit to the existing platform in order to test this solution, and to make a direct comparison with the current inlet.
CRP says additive manufacturing and WINDFORM materials allowed for:
The decision to use the new inlet resulted from its performance and reliability on track. Engineers retained the original airbox, aiming to mount the original air inlet as well as the new one and to acquire data of the airbox pressure on track.
Through the use of reverse engineering, the original airbox was scanned and virtually assembled with the CAD system. This allowed the creation of a new model of the air inlet, taking into account the amount of available space, and the constraints of the assembly of the current airbox and frame.
Once a first draft of the air inlet was developed, a prototype in WINDFORM GF 2.0 was created. It was decided to use WINDFORM GF 2.0 to reduce costs, while being able to perform multiple tests with multiple prototypes.
The first prototype allowed engineers to see if the design fit was correct and suitable for assembly. The first design revealed some sections needed to be changed due to the lack of space available under the lower triple clamp. This problem is further complicated when the bike is cornering and under braking conditions.
To optimise the volume of the inlet duct under the lower triple clamp, the engineers decided to use a portion of the duct in WINDFORM RL, the new rubber-like composite material produced by CRP Technology. This would be bonded to the main structure that was made out of WINDFORM XT 2.0 for evaluation in racing conditions. To facilitate this they also carried out a bonding test to study the characteristics of the final assembly.
The concept required the bottom part of the duct to be made with WINDFORM RL in the fork and triple clamp area, and then to assemble this into the top part produced in WINDFORM XT 2.0. This approach would allow good clear airflow on the straight 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.
In addition, it was decided that making the ducting flexible in the area next to the front forks would of additional benefit. The engineers were able to maximise the duct volume because the maximum steering actions are only reached when the bike is pushed into the paddock. In this situation the front fork can touch the inlet duct, deforming it without any damages.
A second prototype was made in WINDFORM GF 2.0 and the engineers noticed some changes to be made, 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 very smoothly and too much contact of the front wheel assembly gave the impression of drag on steering. This affected the way the rider felt on the bike.
The team and 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 utilised in order to reduce the weight of the front and central part of the inlet, while the WINDFORM RL material was used for the flexible part of the inlet. The two parts were bonded together after being produced.
Image provided by CRP
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