On 26/07/2018 11:38, Bert Coules wrote:
Tim,

Many thanks for your thoughts.Â* The collapse has to be pretty much
instant, so any release of pressure on an inflatable dummy would need to
take immediate effect or nearly so.

Rather than an inflatable dummy, an inflatable frame made from thin
tubing which you can pressurise to make rigid. Use water to pressurise
it, much less volume to lose quickly.

Cheers
--
Clive