Occupant Cell Sizing (Key Document)

ASC Regulations on Sizing tl;dr 

The occupant space by regs is defined by an 835 mm arc pivoting about a designated point. Nothing can be within this arc with the exception of the steering wheel, mirrors, and seats. When occupants are seated normally, with safety-belts and helmets on, no part of the occupant nor the full free range of motion of the occupant's head (with helmet) may extend beyond the occupant cell (defined as roll cage + structural chassis). For ASC there is no minimum amount of space between the occupant's helmet and the extent of the occupant cell. For WSC only, no point of any occupant’s helmet may lie within 50 mm of the extents of the occupant cell.

By regulation, the minimum occupant cell size is based on a 50th percentile male (not including helmet space). Thus, as a team we have a say over who will be able to fit inside our vehicle.

Our Internal Goals for Sizing

We would like to accommodate as many different sized people as possible within our vehicle as we are shipping ourselves as a consumer-oriented passenger vehicle. The industry standard in automotive design is to comfortably accommodate 90 percent of the population ranging from 5th percentile female to a 95th percentile male (think bell-curve distribution of people ranging from small woman to large man). With that being said, we also need to design a competitive vehicle for competition, so comfort will be compromised (to some extent) to optimize vehicle efficiency.

For reference:

Standing height of 95th percentile male: 6'1" (187 cm)

Standing height of 5th percentile female: 5'0" (152 cm)

*Data based on North American population (FSAE Rules95th_2016.pdf)

More detailed break-down of height distribution (Anthropometric Reference Data for Children and Adults - CDC; full report in references)

Occupant Sizing Scenarios

Race Scenario

This applies primarily to our own drivers and passengers with respect to operating the vehicle on a track and during competition. All occupants will be wearing helmets, carrying ballast (ballasted to 80 kg/ 176 lbs), and acting with a competition mindset (focus on efficiency and performance rather than comfort). We have very much control as to who these drivers/passengers will be.

Showroom Scenario

This applies to scenarios where other people, whether they be scrutineers, sponsors, or the general public will be looking at our vehicle. We have no real say over the size/weight of these people and we must do our best to accommodate these people while also managing expectations. These occupants will not be wearing helmets nor carrying ballast and will be assessing the vehicle interior on its look, feel, and comfort for a real-world scenario.

Practicality Scoring Scenario

There is a special case that is a combination of the above 2 scenarios. During competition, our vehicle will be assessed on its "practicality" taking into account both scenarios. During this assessment we will have the opportunity for scrutineers to sit within our vehicle. This may include a test drive with the scrutineer(s) in the passenger seat and/or rear seats. For this test drive, the scrutineer(s) will have to wear a helmet and 5-pt safety harness.

Edit: The values within these 2 tables are only preliminary and are by no means correct

Range of Expected Occupant Size/ Weight

*Note that a helmet is not included in any of these measurements

Who We Are Attempting to Accommodate

*All height percentiles taken from (Anthropometric Reference Data for Children and Adults - CDC)

**Interpolated data

Midnight Sun Sizing Mannequins

Calculated using following spreadsheet: 

References

Regulation Occupant Cell Size

10.3.C Occupant Space

• 10.3.C.1 The occupant space for each occupant’s upper torso shall be defined by an arc defined with an 835 mm radius measured from the hip point as defined in Appendix B of the occupant and projects forward 45 degrees from vertical, 25 degrees rearwards and 7 degrees side-to-side from the centerline of the occupant (this minimum occupant space requirement is based on a 50-percentile male and does not allow for a helmet. Taller team members may need more occupant space).
• 10.3.C.2 The solar car structure, including the windshield must lie wholly outside the occupant space. The steering wheel, mirrors, seat backs, and head restraints may be inside the occupant space but must be designed to minimize the risk of injury to the occupant.
• 10.3.C.3 The driver’s head must be above and behind the driver’s feet. The seat must be appropriately constructed with a solid base and back rest.

10.3.A Occupant Cell
10.3.A.7 The Occupant Cell shall encompass the occupant in all directions. When occupants are seated normally, with safety-belts and helmets on, no part of any occupant, nor the full free range of motion of the occupant’s head (including helmet), may intersect with the convex hull of the occupant cell.