The 2019 Bridgestone World Solar Challenge begins in about 12 months, so this is a good opportunity to summarise changes in the regulations since 2017 (disclaimer: I may have missed something – don’t base your team strategy on what I say!).
General
There are clarifications for several regulations, including signage, licence plate visibility, braking configurations and occupant cell loads. All team members must be in Darwin and registered by 17:00 on October 10th (1.19.2) and, once scrutineering commences, all participating teams must base themselves, and their solar cars, at the Hidden Valley Motor Sports Complex (3.10.2).
Li-ion ‘18650’ cells are deemed to have a cell mass of 47.6 g, which means that at most 420 such cells are allowed for Challenger cars (2.5.4).
Ground sheets
The use of ground sheets generated some controversy in 2017. They now may not be used at control stops at all (3.26.4) and their use is restricted at other times (3.18.2).
Cruisers
There are multiple changes to the Cruiser rules:
- No more than four solar car seats may be occupied while driving (2.12.6).
- Cruiser solar cars must be equipped with a specific kind of on-board ac charger (for use at Tennant Creek and Coober Pedy only). Usage will be metered (2.5.20, 4.4.6).
- Cruisers must arrive at Tennant Creek (stage stop), Coober Pedy (stage stop), and Adelaide (finish) at specified times. Penalties are imposed for average speeds below about 74.5 km/h, with exclusion below about 60 km/h for the first stage and 72.2 km/h for the second (4.4.2, 4.4.5). This will be tough, given that the winning Cruiser in the American Solar Challenge averaged only 48.6 km/h!
- Cruiser scores will be calculated by S = D / E × P × 0.99(l + d), where:
- D is the number of person-km
- E is the nominal external energy use in kWh (initial battery charge plus recharges)
- P is the practicality score of the car
- l is the total lateness at staging locations, in minutes
- d is the number of demerit points received by the team
PrISUm’s 2017 Cruiser Penumbra (photo: Anthony Dekker)
Scientific Gems 
In 2013, when the Cruiser class was first run, there was some controversy about the way the event was organised and scored. This was perfectly understandable since, with no previous events as indicators, no-one knew how the cars would perform.
As we said at the time it would take a while for event organisers, using the benefit of their knowledge of past events, to arrive at a sensible format for the Cruiser class.
Let’s see what FSGP come up with next year.