Sunswift III- the present
2004 saw the UNSW SRT embark on the constructon of UNSW Sunswift III. This car was designed to be a leader on the international stage, boasting advanced aerodynamic design and high-efficiency electrical systems. The car took two years to build and competed in the 2005 World Solar Challenge.
Between 2005 and 2007, various components were redesigned and rebuilt, and in January 2007 the UNSW Solar Racing Team finally suceeded in breaking the Transcontinental World Record from Perth to Sydney. Their car, Jaycar Sunswift III completed the journey in 5.5 days, shattering the previous record of 8 days.
Sunswift III.2 Bottom Shell Layup -- Part 1
Sunswift III.2 Bottom Shell Layup -- Part 2
The car is currently being kept in working condition for educational purposes, testing, driver training and for the possibility of breaking the World Landspeed Record for solar powered vehicles in summer 2009 or 2010.
Quick Facts about Sunswift III
How fast does it go?
UNSW Sunswift III has been driven at up to 120km/h, however it could probably go faster than this. As the speed increases the power required increases dramatically (it is a cubic function), so in solar car racing average speed is of much greater interest! In good conditions (over a long distance) we can expect a cruising speed of 90km/h or more. Our previous solar car, UNSW Sunswift II, reached a maximum speed of 140km/h.
How much is it worth?
In short, solar cars are very expensive. Thankfully, due to the generous support of a number of sponsors, many of the costs to our team are significantly reduced. The major cost is the solar array which drastically increases in price as efficiency increases (and every team wants the most efficient array!). Other significant costs include the carbon fibre composites often used to make solar car body shells, the internal electronics and electric motor. Some cars have been built for as little as $100,000 all the way up to tens-of-millions of dollars. Sunswift III is valued at $270000 most of this is for the array.
How powerful is your solar array?
The current solar array of UNSW Sunswift III produces a peak power output of about 1,800 watts. (the amount of power required to run a toaster) What kind of batteries does it have? We have a relatively small battery pack to store energy for when higher current is required by the motor. This is needed when it is cloudy or when the car is going uphill, and it is also used to even out the speed during the day. Our current battery pack is made up of about 30kg (just under 6kWh) of lithium-polymer cells. They are very energy dense so they are relatively light for the amount of energy you can store in them. They can store enough energy to allow us to travel about 500km at 80km/h or 300km at 100km/h. The range depends on the speed of the car and the terrain. At present we are also using old lithium ion Batteries.
Does it get hot in there?
Yes. The temperature in the car is usually about 10°C above ambient temperature when the car is running. On a sunny day, if the outside air temperature is 35°C, then it will be about 45°C inside. However, when the car is stopped by the side of the road, it can get even hotter as there is no movement of air inside the car.
How much does it weigh?
UNSW Sunswift III weighs only 220kg without the driver and passenger in the vehicle.
What are the dimensions?
The original UNSW Sunswift III seats two people and is approximately 2m wide, 6m long and 1m high.
What is the telemetry system?
A significant portion of the car’s electrical system, including the indicators, brake lights, horn, sensors and driver's display is loosely termed the telemetry and control system. It is based on a type of computer network commonly used in luxury vehicles known as CAN (Control Area Network). The CAN transfers information between all of the electronic devices in the car. These include current and voltage sensors, the motor controller and trackers, the driver's display, the driver's controls, and the car's on-board computer. The on-board computer in turn communicates wirelessly with a support car which allows remote monitoring and control of the car's systems.
What sort of motor do you use?
We use a motor built by the team and developed by the CSIRO. The motor is built into one of the rear wheels of the car, eliminating any losses from having chains, etc. to drive the wheel. It has an efficiency of about 98%. It is a 3 phase, 40 pole DC brushless motor. It has a wound stator surrounded by two rings of magnets which form the rotating outer shell of the wheel. We use a motor controller to switch the phases and control the motor's speed. The motor is also capable of regenerative braking, so the energy used to slow down is converted into electrical energy to charge the batteries. These electric motors sit inside the wheel of the car, providing a direct drive system that reduces the energy consumption of the vehicle by eliminating transmission losses. Wheel motors since have been modified to be suitable for electric vehicle use.
Did you know?
The wheel motor in Sunswift III designed by the CSIRO, is more than 98% efficient (without load drops to ~95).
