the inflateable sail is also known as a double surfaced sail. it's the standard in hanggliding. i had a friend that studied the Macharje(spelling?) book on aerodynamics and developed a double surface sail for windsurfing. he produced quite a few, but no bigshots ever adopted them and won a big race. i used them for a while, but never got dialed in enough to prove they were better than a regular camber induced sail. it would be hard to make one that could be hoisted like a regular sail, but there is potential in the idea.
That's what I had in mind. Are there any pictures of it in use?
Remember, it wasn't long ago that people were saying a square top sail wasn't do-able, or a spinnaker would be "too much" power for a cat.
There may come a day when we all have a solid wing sail, carried in a covered trailer similar to a glider trailer, and you lay the boat on it's side, attach it with 3 or 4 shrouds to support it, tip the boat upright and off you go, might end up being faster to rig than today's A cats! After a day's racing, you take it down, slide it back in the trailer, go find the keg.
Dennis Connor proved the wing sail is faster than the conventional sail back in the 1988 America's Cup on his 60' cat. He had both, tested them, went with the wing. I wish we had more of his testing data available to see exactly how much faster it was, vs. cost, etc.
So, all we really need here is a little Research and Development on this concept and the foiling concept, which is being done by the C class today, as we sit here sailing our 1000 year old conventional soft sail rigs.
Once the details are worked out, we will all be sailing faster, easier, talking about the "Old Days", when people sailed in the water (not over it) with those heavy old masts and inefficient soft sails...