Pressure measurements and comfort of foam safety cushions for confined seating.
BACKGROUND
Glider flights may require the pilot to sit for many hours in a cramped cockpit that allows little movement. Experiments were undertaken to evaluate the performance of different seat cushions in a glider simulator.


METHODS
Subjects were male glider pilots with a maximum height of 1.85 m (6.07 ft) who participated in simulated glider flights lasting 1.5 h. A pressure-mapping device was used to determine cushion performance. By analyzing 15 subjects we calculated the pressure threshold for comfort, above which fidgeting provided objective evidence of discomfort. To determine cushion performance relative to that threshold, 20 other pilots then sat on 5 different viscoelastic foam cushions in the simulator.


RESULTS
The time-averaged peak pressure below which no discomfort-induced fidgeting occurred was 8.8 kPa (1.28 psi). The highest peak pressure at which discomfort could be relieved by fidgeting was 11.0 kPa (1.6 psi). Of the five cushions tested, pressure remained below the discomfort threshold for almost all subjects for only one type of cushion.


CONCLUSIONS
The best-performing cushion had a layered structure made up of approximately 25 mm of Confor C47 foam with an overlay of approximately 13 mm of Confor C45. The other types of energy-absorbing cushions tested, either with or without a softer top layer, are unlikely to provide comfortable seating solutions for most pilots. We conclude that satisfactory cushions are available for this application and that they can be objectively evaluated using this technique.
Jackson
Colin
C
Lasham Gliding Society, Alton, Hampshire, UK. c.jackson32@btinternet.com
Emck
Adrian J
AJ
Hunston
Michael J
MJ
Jarvis
Philip C
PC
D000328:Adult; D000401:Aircraft; D001359:Aviation; D002081:Buttocks; D006801:Humans; D008297:Male; D008422:Materials Testing; D011312:Pressure; D055682:Viscoelastic Substances
D055682:Viscoelastic Substances