To develop a car with high dynamic sensitivity.I honed my own driving sensibility.

So far, I have introduced the idea of ​​"dynamic Kansei engineering" five times while looking back on the development of actual mass-produced vehicles.From the next time, I will go a little deeper and move on to individual technical explanations, but before that, as a summary of the lectures so far, this time I met with dynamic sensibilities, the days I worked on, and the people I will never forget. I would like to talk about the encounter.
For me, talking about dynamic sensibilities is not only talking about concrete examples of RX-7 and Roadster, but also talking about his transition as an engineer. Around 1975, Mazda began developing the first RX-7 SA22C to specialize in the best-matched cars and sports cars, instead of the RE that had been installed in many cars until then in an attempt to recover from the oil shock.For that reason, I was developing Titan in the chassis group of commercial vehicles at that time, and the story of transferring to the chassis group of passenger cars came to me.Although I couldn't transfer due to circumstances, I decided to take on the job of a sports car in the commercial vehicle chassis group, and since that time I have entered the world of sports cars.

I liked the work of the truck chassis, but I had the hope that one day I would like to develop a sports car, so I was very fortunate to have this opportunity.The research on steering stability, which my seniors had been focusing on, was also very interesting, and I was devoted to the design of the SA22C's watt-link rear suspension, which was also taken up in this seminar.After that, the development of the second generation RX-2 FC7S will continue to be in charge of the commercial vehicle chassis group, and since then, sports-related models including the Roadster have traditionally been developed by the commercial vehicle chassis group.
The 1990 SAVANNA RX-7 INFINI specifically focused on the responsiveness of the vehicle, which can be called dynamic sensitivity.

In this car catalog, the transmission of force starting from the steering input is explained with the responsiveness of the vehicle as the ultimate point.At this time, the concept of dynamic sensitivity has not been clarified yet, but the transmission time of the steering system force is less than 0.1 sec, and the driver's feeling is even closer to 1/100 of that. I am.
By the way, the reason why I first became interested in what seems to be the dynamic sensibility of a car.It was the ride quality of the R4 Coupe that my father's acquaintance took when I was in the 360th grade of elementary school.I was surprised and wondered at the comfort of running smoothly on a gravel road full of holes in the countryside.The same is true for bicycles.I remember that it was a new car with no backlash in each part that was able to run stably on a narrow country road.
I mentioned the memory of elementary school because I think that the memory of elementary school is a clear and standard of sensation when I discuss dynamic sensibility.

The ride quality of the R360 Coupe long ago is an unforgettable memory of dynamic sensibilities, but after joining Mazda, the difference between axle suspension and independent suspension is the beginning of that memory.In the 1960s, when motorization began, I experienced Carroll's independent suspension and Familia 1000's axle suspension, but it was Carol who had an excellent dynamic sensitivity to steering stability.Since that time, I have strongly remembered that the quality of dynamic sensibilities would not improve unless the suspension was an independent suspension.

Looking at the development of dynamic sensibility in Mazda, it has a deep relationship with RE and is a technical factor that builds Mazda's uniqueness.For example, the first RE car, Cosmo Sports, was a sports car with a lot of sensibility, but when it was first released, it was not a car with high quality dynamic sensibility.Therefore, the following year, the wheelbase was extended by 150 mm along with the power-up of the engine.It enhances stability at high speeds and improves the quality of dynamic sensitivity.Since that time, Mazda has been actively researching steering stability, so Cosmo's countermeasures were also accurate and highly effective.When I was a new employee, I touched on how the dynamic sensibility and the taste of the car were refined in this way, and remembering it became a valuable asset in the subsequent development.

By the way, when a Japanese car maker engineer asked a Benz engineer what to do to bring the dynamic sensibility closer to Benz, there is an anecdote that he said, "It's 100 years early to approach." ..Mercedes-Benz wanted to convey that it is only possible to improve dynamic sensibility by continuing development activities for that purpose and accumulating achievements over many years, and not overnight.We have been refining the packaging, weight reduction, weight distribution, etc. of Mazda vehicles for many years in order to enhance the dynamic sensitivity of Mazda vehicles.We are proud that this succession is what makes Mazda cars unique and attractive because of the driving sensation that reacts to cracks.

In order to develop a car with high dynamic sensitivity, I also tried to improve my driving sensitivity without staying in the design room.Driving sensibilities need to be collated with memory from the above-mentioned process of creating dynamic sensibilities to recognition, and it is important to accumulate experiences and enrich dynamic sensibility memories.The dynamic sensibility of the limit area of ​​the car must be accompanied by a first-class driver and listen to what kind of words the impression is expressed.
However, it is also extremely important to hone your driving skills and experience the behavior.This is because dynamic sensibilities can only be perceived by driving, not by words.

One journalist once said, "When I test drive, I can hear the car language from somewhere in the car." "I translate the car language into Japanese and critique it." I feel that it is a phenomenon like telepathy that appeals to the heart like that.By the way, I first improved my driving sensibility in the limit area of ​​vehicle behavior when I entered Jim Russell Racing Drivers School in Laguna Seca, USA in the early 1980s.It was a very short course for only one day, but when I went down the corkscrew, I felt like a racing driver.

Until then, the sharpness of the steering response of the cart was the standard, but the sharpness of the cigar type school car is clear as a new standard of dynamic sensitivity, and the steering response of the first RX-7 seems to be dull. It was such an experience.At the same time, I also drove on the Willow Springs International Raceway in the northern part of Los Angeles and experienced the feeling of maneuvering in the desert climate.After that, in the suspension development of the 323 Group A rally car that participated in the Monte Carlo Rally, and the rough road driving in the suspension development of the WRC RX-7 rally car, I experienced the limit driving of the vehicle on the general road and the attitude control characteristics.

The skill and sensibility of the driver who hits the counter while the rally car jumps nearly 1970m and touches the ground and controls the posture at the same time as landing is unbelievable even if it is on board, and it is a different dimension reminiscent of an animal feeling.I felt that we had to have a car that would satisfy even drivers with such dynamic sensibilities as the standard for the limits of commercial vehicles.In addition, an environment for final confirmation is important for the maturation of dynamic sensibilities. In the XNUMXs, Japanese cars began testing in the Nurburgring in the European market to gain a high level of dynamic sensitivity at high speeds, but Mazda went to the site earlier than that boom.

It is a 22km circuit where ordinary vehicles buy tickets for each lap and try the limit driving, but at the time of the first experience, I remember running on the unimaginable high speed course just crazy.
In this way, in order to design and develop a car with high dynamic sensitivity, I think it is essential to experience the limit performance of the vehicle by myself.In Japan, design engineers and research engineers are often organized as individual jobs, but instead of relying solely on the reports of the research engineers, the design accuracy can be improved by experiencing them for themselves. I have been trying to improve.

Of course, it is clear that there is a limit to the skill, and in order to cover it, we have been actively asking skillful professional drivers for a ride evaluation.Above all, it was an honor to be accompanied by Paul Freres, who I admire, and to be evaluated. It happened more than 20 years ago, but when I was inadvertently asking a question while riding a Roadster development car at the Nurburgring, I was told, "I'm focused now, so I'd like you to ask a question later." There was also.
At that time, Paul Freres was Nur.It was said that he ran more than 1700 laps, but despite being such an experienced driver, he was constantly sharpening his sensibility and was deeply impressed by the dignified professional driver's attitude.When he gave high marks to the dynamic sensibility of the developed car, it was a pleasure to completely forget his hardships.At the Paul Freres Driving School held at the Mazda Miyoshi Proving Ground, I remember being pointed out that "you are too early in the steering point" when entering the corner.

I have talked about how I have emphasized dynamic sensibilities in designing and developing sports cars, and how I have continued to transfer the memories of those sensibilities to cars.The value of dynamic sensibility is a fountain of rich emotions created between people and cars.Also, rather than thinking of a car as a mere tool for transportation, it finds value in the process of transportation and expands the joy of driving many times.Of course, I can't do that by myself, but I'm convinced that he has done a satisfactory job by comparing the various cars he was in charge of at Mazda with his own sensibility.

Up until this time, I had recollected my dynamic sensibility centered on the development of vehicle models such as the RX-7 and Roadster, but from the next time I would like to move on to a more academic lecture on dynamic kansei engineering.I would like to elucidate the dynamic sensibilities while unraveling the physical principles of automobile engineering in an easy-to-understand manner.Please look forward to it.