No one has ever really questioned the actual protection that rib protectors offer, so we wanted to look a bit closer into the issue. So we decided to look into this topic, rib-protectors that are very much a part of karting and so commonly used and “taken for granted” that they have never been really studied in detail. No one has ever doubted the fact that rib protectors are fundamental for a kart driver, then there are cases like Mattia’s, having the weight of a kart on you is no joke, the rib protector was of uttermost importance. Then there are the various bumps, the effects of normal driving during race weekends when there are loads of races to do. Lots of “bangs” – and not just slight ones, if you hit the curb… at the end of the day they all add up.
Appointment at Valle del Liri
I get to the circuit at 10:10 am and I wear the official DR pilot suit for one day: the well organised team is setting up the karts and among them there’s “my” OKJ. Besides them there’s also Bruno and Riccardo Mazzeschi in charge of the MIR Racing Line, Andrea Saccucci and Daniele Parravano from Officine in Progress. Andrea and Daniele have mounted an ‘Orion’ box and several sensors for obtaining data were put on me, sensors that will monitor body response whilst driving. The chassis and the engine were in expert hands, Marco Rossi’s. Thanks to the characteristics of Arce, it’ a great track for testing the engine: the first turn (Enzo Ferrari turn) that can be covered almost without closing gas, allows you to “evaluate chassis response racing at high speed and so do the narrow turns (ramp 1 and ramp 2) that lead to the second straight. You can see how agile the kart is on a mixed part of the track. The characteristics of the asphalt are such that early on during the day you can’t take data regarding time, but evidently on pre-racing day as there are lots of karts on the track the asphalt is better performing sooner. Obviously, carrying out the test during the week means that you have to follow the changing track conditions with the right setup. Usually we can approximately say that there’s on average one second different from when the asphalt is at its best and the track on normal days.
The VEGA tyres being used are in excellent conditions, but here too, you can easily find a 2-4 tenths difference between a new set and a set that has already done one or two sessions. Marco Rossi thinks that in today’s track conditions a good time to stop could be 49”40 while on a track with good grip for racing it should be about 48”30. The first session was just five laps to set the sensors and rib protector; in any case, I take advantage of the situation and warm up tyres so from second lap on I press hard. Already from the first lap, I’m really surprised by the braking system: the brakes on the DR are better than those on karts I had driver before and they allow you to delay braking without upsetting the chassis. The MIR rib protector is very comfortable and despite the high temperature there’s no problem with sweating, while when driving along the bumpy part of the track it allows me to keep gas open without feeling any uncomfortable blows at ribs. Differently to my rigid rib protector vest the PRO TOR – EIP vest has vertical strips that are ultra shock absorbent and anti-vibration that the soften blows and absorb the impact without “hurting” (I had further confirmation the following morning when I noticed that I didn’t have any of the usual bruises on my torso or any aches and pains, which aren’t very nice, connected with it. For the next session, Andrea puts another sensor on my vest, this one is for monitoring the degree of sweat, Marco Rossi sets the pressure and slightly touches up carburetion, and back I go to the track with the following setup:
Tyres: Vega HX
Front pressure: 0.66 bar
Rear pressure: 0.64 bar
Front track: 122 cm
Rear track: 140 cm
Camber: 4 mm open below
Toe-in: 4 mm open
The session is longer this time, about 8 laps. Carburetion is slightly leaner at high revs allows me to do more laps and at a speed you feel especially at the braking point of the turn that leads to the main straight (the American’s turn). With the new pressure I tend to improve with each lap, but the track still hasn’t got much grip and without the right entry, when I try to steer the forecarriage tips and from half way through the turn the rear starts jumping. I go back to the pit and as I tell Marco what had happened, my sensations, before I even finish, he says that he had already noticed it all, and it’s necessary to adjust the chassis to track conditions loading the angle of incidence “caster” by at least one degree more. Having changed setup, the chassis is perfect on the lap that follows, chassis response is absolutely neutral and this allows me to gain important tenths round turns. When they gave me the Ok from the pit to fiddle around with the carburettor, I easily go below the”theoretic crono” set by Marco. On the last session they mounted a set of tyres that still had the line (practically it had just been run in) and seeing the high temperatures of the asphalt (with the tendency to slightly increase lap time after the seventh lap) the tyre pressure is slightly lowered, from 0.66 to 0.62 bar for the front and from 0.64 to 0.60 bar for the rear. Lap time stopped goes down by another three tenths and this is quite satisfactory. Personally, I can only confirm the brilliant sensation that I got on the DR and with TM engine not to mention the rib protector, really great.
We are used to using “mechanical” sensors on karts, that is, the ones that register acceleration, movement and so on. But when you are “measuring” monitoring the human body, the driver’s, what do you use? In this case too, it depends on the data that you want to study: for example, through an EMG sensor (electromyography) you can register the action of muscles and nerves, which starts off by a very weak current, and with this information we can find important data concerning stress and driver’s reaction. Instead, for sweat, this changes the electrical activity of the skin, and for this reason special sensors for this “read” the skin through electrodes. The value you get from these sensors is directly in millivolts, therefore you compare the results u get under stress with results you get in normal mal conditions (for example 20°C when resting and so on). To check stress that the driver’s body is subject to, instead we used a normal triaxial sensor for accelerations, even if in this specific case we decided to measure one axis at a time (longitudinal or transversal) to differentiate the ones in acceleration from braking. This sensor was placed (stuck) on my rib protector vest at rib height. The rib protector being tested was the new MIR PRO-tor EIP (extreme impact protection) that applies this new “philosophy” to soften blows by allowing force to dissipate from a soft material instead of a stiff material. The tests were carried out in two separate moments, on the track with the driver and in the laboratory. As the driver on the track said afterward, “there were no problems as far as sweat was concerned, while in the bumpy part of the track, it allowed me to press down on gas pedal without feeling any uncomfortable blow on the ribs”. What is the actual reason for this? Let’s see… On the track we measured acceleration both on kart (chassis) and driver, and we found the latter higher. The reason is simple, the sensor placed on the driver is at a higher level and the further we go from the ground the more the movement (hence stress) become lateral, with greater load transfer.
Stiff rib protectors and soft ones have different characteristics but the same aim: protect the driver from strong lateral acceleration. However, in case of accidents, especially if the vehicle overturns when the driver isn’t thrown out of the kart but remains caught up in it unfortunately luck (besides the weight f the kart ) play san important role. In the motorcycling field, where in case of a fall the driver rarely remains caught up in the kart, for some time now the system with an airbag system is integrated in the suit, and thanks to this the accelerometers take the blow and the kart overturning by opening some air pockets at the points which are most at risk. Materials are being studied that, in case of blows, they get stiffer and form a sort of shell around the driver.