Determining aircrew helmet size design requirements using statistical analysis of anthropometric data

Area of Science:

• Aerospace Engineering
• Human Factors Engineering
• Anthropometry

Background:

• Traditional aircrew helmet sizing relies on head length and breadth.
• Emerging helmet-mounted display technology necessitates incorporating a third dimension: pupil-vertex height.
• Previous anthropometric data for aircrew may not fully address modern technological requirements.

Purpose of the Study:

• To determine an optimal number of aircrew helmet sizes accounting for head length, breadth, and pupil-vertex height.
• To improve helmet fit quality for a larger percentage of the aircrew population.
• To evaluate the trade-off between the number of helmet sizes and fitting quality.

Main Methods:

• Utilized data from the "An Anthropometric Survey of 2000 Royal Air Force Aircrew, 1970/1971."
• Plotted three head dimensions (length, breadth, pupil-vertex height) for each subject.
• Calculated the minimum number of helmet sizes for a reasonable fit.

Main Results:

• Nine helmet sizes were found to provide a reasonable fit for 93.5% of subjects clustered around the population mean.
• Increasing the fit percentage significantly requires either more sizes or reduced fitting standards.
• The study identified a practical limit for helmet sizing based on current anthropometric data.

Conclusions:

• Incorporating pupil-vertex height is crucial for modern aircrew helmet design.
• Nine sizes offer a practical balance between fit coverage and inventory management.
• Further optimization may require updated anthropometric surveys or advanced fitting technologies.