When designing a car (or undertaking any large project) it is always wise to start with the end goal in mind. This is my end goal:
My main inspiration for the layout and body of my car is the Aprilia Magnet designed by the Finnish designer Heikki Naulapää. Heikki’s full design study is here:
Some obvious things that I would have to change from Heikki’s design are:
- Wheels – no one manufacture hubless wheels, so I’ll have to use conventional motorcycle wheels
- Steering wheel – a regular steering wheel is probably easier to design and more ergonomic than his two- post setup
- Rear suspension – it will be easier and cheaper to just reuse an existing rear motorcycle suspension
But in general, I want to keep the overall design of a three-wheeled tilting car with a two-person tandem seating design similar to a motorcycle. To maximize acceleration, I want to make the car all wheel drive. I want the excitement and the feel of riding a motorcycle with the capability, safety and control of a car. People’s sense of riding a motorcycle is created by a number of factors. Firstly, the experience is very open – rather than seeing the world through the picture box of a car window, the motorcycle rider is out “in” the environment. In his book “Zen and the Art of Motorcycle Maintenance”, Robert Pirsig called this an overwhelming “sense of presence.” There is a sense of exposure and danger because riding a motorcycle is, in fact, dangerous. The exhilarating feeling of riding a motorcycle comes down to the high power-to-weight ratio and the sensation of leaning into corners. By giving the rider the stability of three wheels and tilting into corners, the car will give the driver the feeling of riding a motorcycle without the safety and stability drawbacks. Aesthetically, I think Heikki nailed it – the Magnet builds on the Scandinavian design tradition of simplicity and minimalism. Form follows function and nothing superfluous is added. I’m hoping that by following the same philosophy, my design will look just as beautiful.
Advantages of Electric Vehicles
- 100% torque from zero RPM – instant acceleration of the line means better overall acceleration.
- Flat torque curve – can provide massive power at nearly any speed without a transmission.
- Virtually maintenance-free – only 1 main moving part. No need to change oil, oil filters, air filters, or spark plugs.
- Reliable – fewer moving parts means electric drives can be more reliable than internal combustion engines.
- Quiet – electric motors can be far quieter than internal combustion engines. This benefits everyone by cutting down on noise pollution. South Park literally did an entire episode about how much people hate loud Harley riders. It benefits the driver by being able to enjoy the sounds of their surroundings more.
- Efficient – Electric motors can be over 90% efficient while internal combustion engines are usually around 20% efficient. Electric motors use no power when the car is stopped at a stoplight while most cars continue to idle.
- Sustainable – can be charged with renewably-generated electricity. Even when charged with fossil-fuel-produced electricity, the high efficiency of electric motors makes the overall emissions far lower. No need to worry about contributing to pollution, climate change, peak oil or sending money to oil-producing countries that fund terrorists. Makes you more resilient to oil shocks and inevitable carbon taxes.
Disadvantages of Electric Vehicles
- Range – Since gasoline is 32.5 times more energy dense as an energy carrier than lithium-ion batteries, electric cars are limited in how much energy then can carry.
- Recharge time – Electric cars take far longer to charge than gasoline cars take to fill up.
- Cost – While the lifetime cost of an electric car can be cheaper than a gasoline car, the up-front cost will almost always be higher due to the cost of batteries.
Advantages of Tilting 3-Wheelers
- Simplicity – A three wheeled vehicle has the fewest number of wheels while still being inherently stable. (of course for stability you need 2 wheels in the front and 1 in the back, not the other way around like the Reliant Robin) Three-wheelers can corner at up to 1.3 G’s while motorcycles rarely exceed 1 G. Three-Wheelers can also out-brake motorcycles. Simplicity of design also leads to lower cost and higher reliability.
- Lightness – Having 1 less wheel than a car means the design can be lighter. All things equal a lighter car will be more efficient and have higher performance.
- Registered as a motorcycle – In most states, 3-wheelers that weigh less than 1500 lbs are registered as motorcycles. This means they need to follow fewer regulations, which allows then to be simpler and lighter. Motorcycle insurance is also typically cheaper than car insurance.
- HOV Lane Access – Since 3-wheelers are technically “motorcycles,” they are allowed access to the carpool lanes in most states.
Disadvantages of Tilting 3-Wheelers
- Too different – When you drive down the street all of the cars look pretty much the same. When a Red Ferrari drives through the crowd of beige, it stands out. Most people don’t like to stand out. People also have a distrust of the unconventional. Jalopnik argues that 3-wheelers fail the “Most Advanced, Yet Acceptable” test.
- Tandem seating – While motorcycle owners are used to this configuration, most car owners are not. People like to sit next to each other so it’s easy to talk.
- You hit every bump – With a normal 4-wheeled car, when you see a pothole or a rock in the road you can simply aim so it passes under the center of your car. With a motorcycle you can swerve around them. With a 3-wheeler, there’s no avoiding every pothole and rock in the road. Also, if you drive in the snow or on a dirt road, 4-wheel cars put two ruts in the road, but the 3-wheeler’s back wheel will ride up on the center.
- Low passive safety – While small nimble cars have higher “active safety” than larger vehicles, because they are better able to avoid collisions in the first place, vehicles with less mass usually have worse “passive safety” than vehicles with larger mass (Newton’s laws of motion).
- Low space – most 3-wheelers offer about as much storage space as a motorcycle.
My engineering goals, in order of importance, are:
- Safety – safety should always the the #1 goal of any design. Do it safety or not at all. There’s always time to do it right – so even if it takes longer to design, it have to be designed with safety as the primary goal.
- Compliance – The vehcile must fully comply with all applicable rules and regulations for making it street legal.
- Excellent Handling – low overall mass, low unspring weight, low yaw polar moment of inertia, low center of mass, even weight distribution, low load transfer, optimized suspension geometry
- Good Acceleration and Braking – high power-to-weight ratio, efficient drivetrain, all wheel drive, advanced brakes and tires. I’d like to set a goal of 0-60 mph acceleration in less than 6.0 seconds.
- Reliability – standardized components, simplicity, redundancy, maintenance-free components
- Sustainability – I want to design and build the car to be as sustainable as possible – the manufacturing and use of the car should create zero pollution and the entire vehicle should be 100% recyclable
- Decent Range – I’d like to achieve a minimum range 150 miles. This is nearly double the Nissan Leaf range and is enough for most weekend trips.
- Decent Top Speed – While low-speed handling is more important, I’d like the car to have a top speed over 100 mph.
- Low Cost – standardized components, minimal manufacturing labor, low company overhead
Boiled down, this design philosophy is best described by the late Colin Chapman’s famous line “Simplify, then add lightness.” As Chapman went on to explain, “Adding power makes you faster on the straights, subtracting weight makes you faster everywhere.”
In quantifying the success of the design, we can follow Peter Drucker’s advice: “what gets measured gets managed.” We can measure success by a few simple measurements:
1. Minimize vehicle mass – the lower the better, particularly for unsprung mass.
2. Minimize total vehicle parts count – the lower the better. Avoid “feature creep” – if a component isn’t absolutely necessary to produce a the minimum viable product, it should be thrown out.
Fighting Automotive Obesity
Almost everywhere you look in modern car design, you see companies failing to follow Colin Chapman’s advice about simplicity and lightness. Feature creep, stricter safety requirements and a desire for more interior space has caused nearly every modern car grow fatter from its origins. The following list shows the lbs gained between a model’s first year in production and the current model:
- Chverlet Suburban – 2.214
- Toyota Land Cruiser – 2,039
- Nissan GTR – 1,481
- Ford F150 – 1,429
- Toyota Carolla – 1,211
- Mercedes E-class – 1,110
- Honda Accord – 1,109
- Honda Civic – 1,095
- Mitsubishi Lancer – 1,025
- BMW M3 – 915
- Volkswagen Golf – 907
- Toyota Camry – 886
- Lotus Elise – 298
- Subaru Impresa – 240
- Smart Fortwo – 43
- Audi S4 – lost 176
I own an Audi S4 (B7), which is one of the only cars I could find that lost weight between its introduction and the current model. Nevertheless, the car is still very heavy, tipping the scales at over 1.8 short tons. While the 340 horsepower V8 is able to overcome that weight and accelerate the car to crazy speeds, at low speeds the weight is very noticeable. The problem with trying to compensate for weight by adding horsepower is that at low speeds, the handling is still compromised by the weight. While it is exciting to drive at triple-digit MPH speeds, in real day-to-day driving I hardly ever take corners at speeds faster than 50 MPH. I believe that car companies have forgotten that truly “fun” cars need to have both a high horsepower-to-weight ratio and a low overall mass. A few cars, like the Subaru BRZ/Scion FRS, break this trend and provide exciting low-speed driving, but in general performance cars have gotten far too heavy. So I’m considering this project a 1-man crusade against automotive obesity.
The actual design work consists of selecting components by calculating loads, modeling those components in 3D Solidworks and assembling them virtually into a full vehicle model. This work can proceed in any order, but it makes the work far easier if it is done in a natural progression. I am starting from the tires and moving upwards and inwards. The tires are the most important component of any vehicle – they are the only component that touches the road and as such, they are responsible for all acceleration, braking and cornering. By designing inward from the tires, it keeps the focus on these components, creating a “tire-centric” design.
I’m also planning to use all metric measurements and metric-sized parts, because the metric system is better.
I maintain a Pinterest board to help me organize my design thoughts.