A not inconsiderable advantage of using air propellers instead of water is that the cat can be run along the ground for launch, or over sandbanks in operation. To facilitate I recommend a strip of adhesive steel tape be applied to the underside of the skis. They ship in 5m lengths, matching that of the skirting we've used for those skis.
When I worked in airliner simulators it was all about using 'commercial off the shelf' solutions (COTS) for building such devices, for if you didn't then you'd be leapfrogged by people like Loft Dynamics... who claim to cut the cost of training by ten or twenty:
Much as I love them, incidentally, by from the original suppliers to avoid B & Q's 25%.
