But being "fit for purpose" doesn't come into RIAT does it?
If they charged you money, let you in and then there were only static displays, perhaps you could make a case for it not being fit for purpose as an Air Display.
You mention "the product was faulty", but again that does not apply. There was nothing wrong with the product, just the weather, which no-one could have "reasonably" predicted.
If RIAT had decided to invoke their conditions of sale, yes they would have hacked off a lot of the punters, but they would have been well within their rights to do so.
Cheers
Stew