Smaller, Lighter, Stronger
Together with stylish Kodo design, the new Roadster's bodyshell also incorporates Mazda's Skyactiv thinking to add strength and save weight. Advancements in the materials used and construction methods help the new car achieve the overall weight saving of around 100kg.
The new design bodyshape is a little shorter and wider than the previous cars with the standard ride height around the same at 140mm. The most noticeable difference is probably the position of the wheels within the body - they are pushed as far into each corner as possible. Advances such as the new compact LED headlight units have enabled Mazda to achieve this design. The new car's dimensions are length 3915mm, width 1735mm, and height 1235mm.
When comparing to the NC, the basic layout of the car is the same but the proportions have been tweaked and the positioning of key components further refined. The overall height of the car is down by 10mm, the driver sits 20mm lower in the car, and the wheelbase has been reduced by 20mm. Front and rear bumper overhang has been cut by 45mm and 40mm, helping to give the car a much sharper look as well as reducing weight.
The new Roadster's body is built using various strengths of steel and aluminium. The material mix was chosen to achieve the desired weight savings and improvements in crash safety. The use of higher strength steel than in the previous NC allows less material to be used without losing structural strength.
The ND's body also makes increased use of aluminium compared to the older cars. These advances have resulted in the ND having a body-in-white weight of just 197kg; compare this with 217kg for the NC, 230kg for the NB, and 211kg for the original NA.
Aluminum is used for the bonnet, front wings, front bumper reinforcement, chassis tunnel braces, differential casing, roll bar, rear bulkhead panel, bootlid, rear bumper reinforcement, interior access panel, roof frame & front panel, wiring loom, front wishbones, undertray, and wheel uprights.
The ND's body is made up of a greater proportion of stronger grades of steel than the previous car. Mazda's use of stronger material together with advanced structure enhances crash safety. Skyactiv body uses the concept of load paths to direct impact energy around the car's occupants, in effect creating a 'safety cell' in the cabin.
Wherever possible the body structure design makes use of straight lines and high tensile strength steel box section. The front and rear subframes are an integral part of the crash structure creating upper and lower load paths to absorb energy. The bar behind the seats provides a degree of protection in the unlikely event of a roll over and also contributes to side impact strength.
I'll be talking more about the ND's safety features in a future post. The more I read about the new Roadster, the more impressed I am with Mazda has achieved here. The factual information discussed on this page comes from Mazda's Technical Review #32.
