Ted
The engine is direct drive, no belts. the skirt is made of a ripstop nylon (tough) material, and the floor area behind the prop has an opening for some of the air from the motor to go to blow up the skirt. on my model, there is also an inner tube that goes around the underside of the craft, inside the skirt, that has an inner tube air valve that you actually pump up so that there is always positive flotation available. think of the skirt as a half round object connected to the outside of the deck, and to a place 3 inches in from that on the bottom of the craft. the engine blows it up, and the relief holes on the inside of the skirt dump excess air toward the inside void under the craft. this air then escapes out from under the blown up skirt, thus creating an air "cushion" for the vehicle to ride on. you can see that having a hard surface to run on is pretty important.. they dont do well on grass. i think one engine will do the trick, but if you insist on two, probably an 049 will blow plenty of air for the skirt. the lighter the better. JB