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KG PLASTICS: AERODYNAMICS

Max Bernardi

13 July 2016

The new 505 model fairings represent the utmost development in aerodynamic terms by KG, a leading manufacturer of fairings and kart accessories

When talking about fairings related to karting, it is impossible not to mention KG: the Italian company has thirty years of experience in the field and currently supplies many of the major chassis manufacturers. The first fairings created by KG were square-shaped and specifically for the lateral protection of the kart. Nowadays, however, fairing kits include a front spoiler, two side pods, front fairing and rear bumper. They are not only essential for safety, but also when it comes to performance on the track.

RESEARCH AND DEVELOPMENT

KG has several fairing models for karts in its catalogue, but the 505 is definitely the one that represents the greatest effort in terms of design and development. Unlike in the past, the primary objective during the design and manufacturing processes of this fairing kit was aerodynamics research. To solve the various problems in this field, KG carried out studies on fluid dynamics using software provided by Aotech, a French laboratory specialised in CFD applied to motorsport.

GOAL

The goal of the KG 505 fairing kit is to reduce aerodynamic drag in order to increase the penetration of the kart and driver. Another, not secondary, goal is to have a more linear air flow in the air intake silencer, radiator and brakes area, which mean improved engine and braking system performance on the kart. The above had to take into account the stringent crash tests imposed by the Federation to ensure the safety and effectiveness of the protections in the event of an accident.

THEORY

During the design stage, several changes were made to achieve maximum benefit in terms of "Drag", i.e. air resistance (CX), but above all of "downforce" (CZ), i.e. the force generated by the profiles that are orthogonal to the floor of the kart. In this sense, the nose panel of the 505 model acts as a wing, pushing the kart downwards. The lower area was subjected to the most study and work: as in F1 cars with an extractor, the benefits to be had are enormous and are not in contradiction with each other, because the load normally penalises advancement. Following the principles of the "Venturi effect", which states that increases to flow speed correspond to a decrease in its pressure, it was possible to achieve the goal of creating a slight "suction" effect that pushes the front end "downwards".

COMPARISON

To develop the basic 505 hulls kits were evidence of The CFD (Computer Fluid Dynamics) tests carried out at the Aotech laboratory were essential to the development of the 505 fairing kit. The software that simulates aerodynamics allowed KG engineers to change the model until they were able to identify the best profile. A comparison between the BURU kit (also produced by KG) and the new 505 highlights the differences in the lower and frontal areas of the spoiler and the flows generated laterally.

BURU

505

From pictures of the two models (above; the BURU, below, the 505) you can clearly see the difference in pressure which air exerts on the lower part of the nose panel. The gradient that goes from light blue to blue indicates lower pressure and therefore greater “downforce”: from this point of view, the more light blue colouration of the 505 indicates air flowing at a higher speed.
At the same time, it is evident that the flow more linear along the front spoiler.

The frontal pictures show the pressure areas that influence drag: on the 505 kit, the most benefit was achieved by trying to minimise the surface areas with a frontal impact. On the central part, which is reddest and therefore has the highest impact with air, KG technicians were unable to improve performance compared to BURU kits because, according to the regulations, the CIK requires a minimum flat, rectangular central area that is 800 mm wide and 80 mm in height.

A comparison of the two fairing kits on the right side area highlights how the flow to the air intake silencer has been improved in the model 505, with a straighter trajectory and less turbulence in the lower part.

The left side part of the kart directs air flow towards the lower area of the front brakes, the radiator and the rear brakes. The pictures show that the amount of air in the 505 model is greater and also faster (see circled part). This advantage is determined by the lateral part of the front spoiler which, being tapered, allows turbulence-free, and therefor faster, flow.

RESULTS

Once work moved from a computer to the track, tests performed by KG confirmed an improvement in front grip using the 505 fairing kit. However, the advantage can be appreciated when the set-up is designed to maintain a good balance between the rear axle and the front and, in order to achieve it, compared to a kit that is more neutral in terms of aerodynamic performance, the 505 requires work on the set-up of the kart, otherwise there could be some imbalance towards the front. In fact, with the 505 the front spoiler is a real wing and its behaviour varies depending on the inclination. The CFD data shown in the table relates to assembly with the bumper assembly area perpendicular to the ground. To lighten the front, all you need to do is raise the tip of the spoiler by, for example, adjusting the fastening ring.