I think the aircraft that is on the books now is a "spare / demonstrator" any future shares sold would require a purchase.
There were rumours of 2 non-refundable deposits placed last year for aircraft.
I guess you would be really hacked off if you only sold 15 sixteenths?
I don't know this for sure, one sixteenth costs £125,000, this means that a whole aircraft would be sold for £2,000,000. The '99 / 00 CJ is probably worth about $2.8M so I suspect the shares being sold are for a later model CJ1.
The profit comes from the monthly management fee charged for the use of your hours.