Ted
my experience says that a nitro engine can run in just about any position, and running one upside down to lower the cg is a good idea for a hovercraft. i agree with our friend from japan, you cant really adjust the hover height, you just need enough air to create a little clearance between the skirt and ground . i wouldnt throttle an 049. just use the needle to fatten it up or lean it out to get the rpms you need. you may have to play with the cuts on the inside of the skirt to get the right amount of air escaping to create the small cushion. you are starting to understand that these things are a lot of trial and error when you go scratchbuilding. from the ground up, airboats are a whole lot easier to build. but there is something about watching that craft float around like a magic carpet that is way too cool........