Clever Kart Republic Go Full Aero at FIA KZ World Championship
Nifty workarounds as Kart Republic reveal dramatic floor addition.
tKart have released some pictures from the Thursday at the KZ World Championships that show Kart Republic using a shapely floor tray that is very heavy on the aero front, as well as a clever floor workaround under the seat.
The workaround has existed for a while, and I even drew up some pictures myself of this idea, but alas never got round to actually building it. I can’t tell how frustrated I am right now! So here’s how it works; the floor tray has to end at the central strut of the chassis. Now both the FIA and Motorsport UK don’t really define where the central strut should be, but let’s forget that for now.
It is generally accepted a flat tray under a kart is better as it accelerates airflow, producing low pressure, and thus downforce. In a sprint kart it’s a small amount, but it’s enough to potentially make a difference. Now what KR have done is extend the floor tray, exactly what you’d want to do. However bodywork on a kart must be homologated, so just bolting a tray to the chassis would constitute bodywork, in my view and be subject to the mandates surrounding said homologation.
If, however, you change the seat to additionally include a large flat surface underneath, then you get the same effect as extending the floor tray. I went as far as designing a diffuser into it, but KR have just come up with two brackets that attach to the seat which then bolts to a flat floor. It’s a bit brutal in exception. What this does though is mean effectively the flat area is part of the ‘seat’. It isn’t bolted to the chassis, and thus not bodywork.
Regarding sculpted normal floor tray itself. it’s clearly designed to to drive more air under the kart. Something the regs seems to allow as they are pretty thin and seem open to interpretation. This is the FIA regulations.
"4.6 Floor tray It is mandatory to have a floor tray made of rigid material stretching from the central strut to the front of the chassis frame. It must be laterally edged by a tube or a rim preventing the driver’s feet from sliding off the floor tray. The floor tray may be perforated, but the holes must not have a diameter of more than 10 mm and they must be separated by four times their diameter as a minimum. In addition, two holes with a maximum diameter of 35 mm are allowed for steering column and/or gear shift lever access. The floor tray may be made of composite material. "
Motorsport UK’s regulations seem to be more detailed. Section U of the Yearbook states "16.6.1. The floor tray must be flat, with any deviation allowed upwards, and not downward.” They aren’t without ambiguity however. When is down actually up?
We’ll wait and see what happens and whether it’s declared legal. The seat is a clever workaround. Provided the teams could find something flat, they could copy the under seat floor quite easily overnight, nulling any potential advantage there. The sculpted floor tray however might be more of an issue. We’ll see if it’s all deemed legal.
It’s not the first time however this kind of thing has appeared at a World Championship event. In 1979 Zip Kart tested a full floor tray and diffuser with Martin Smart at Estoril.
We shall watch this weekend’s racing with a keen eye!
Good write up. I'm still angry about that front tray though 😂