I know this is an old post but I thought I'd share how I set up my hovercraft that I built yesterday. I wanted to try several different ways of controlling the two motors. I set up one of the three position switches to control it three different ways.
The 1st, is what I'm calling "hover mode." When I move the throttle stick up, only the lift motor spools up. The thrust motor is attached to the elevator stick. This is nice in some ways because you can have it hover without driving into something. Good for taxiing or areas that have a lot of obstacles. Or testing it out in the pool (works great). To do this I have each motor in a separate channel and the elevator channel within my Taranis is set at -100% I believe. So when it's at center stick, it's reading zero. I may be wrong on the %.
The 2nd, I don't really have a name for, "throttle mode" maybe? In this one each motor is still in a separate channel, but they are partially mixed together in my Taranis. This is probably my favorite because I have it setup where the thrust motor doesn't kick on until the lift motor is at 50% power. This way you can hover, and as you go past 50% on the throttle stick the thrust most kicks on. It eventually catches up to the lift motor at about 75% power. This way seems to work really well and is the best of both worlds. If anyone wants details on the Taranis Mixes let me know and I'll get them.
The last way is how Peter had his hooked up, both motors run off the same stick, on the same power. So 50% stick = 50% power on thrust and lift. This works fine it just seems like it always trying to go really fast, and I have a lot of trees in the yard... I still have the motors in separate channels they are just mixed together within the radio. I didn't use a y-harness so I could get the other two methods to work with unplugging and plugging in things.
Hope this helps someone making a hovercraft. Mine is a lot of fun, but this year I'll actually be excited about snow/ice.