Last Saturday, when the "let's build a hovercraft!" impulse hit, we went to a thrift store and bought a couple old vacuum cleaners, hoping to find an engine capable of enough pressure for a hovercraft.
Here's the engine, and here's the problem with it. The obvious "pipe" at the front is the air intake - that's where the vacuum cleaner hose is attached. But there isn't a single air output - the engine sucks air in through the pipe and then blows it out in all directions. Should we ever spontaneously decide to build a hunkercraft, that'd probably work great. :) For a hovercraft, you need to push all the air directly down at the ground to hold you up.
So the obvious solution is to put the engine inside a bucket, at least, if you're cheapskates randomly building a hovercraft for thrills. This way, air might come out of the engine in all directions, but it can only go down to get out. So yesterday we went and bought one with an airtight lid, and cut a hole in the bottom of the bucket for the air intake.
The is the engine bolted to the inside of the bucket with improvised clamps bent from sheet metal. Blacksmiths love an excuse to bend metal. :)
This is ordinary weatherstripping like you'd put around windows to keep snow and cold air out. Here, its an airtight seal from the bucket to the hovercraft platform so that none of the valuable air pressure is lost.
The lid of the bucket, bolted to the hovercraft platform.
We accidently left a nut caught between the plastic lid and the wooden platform and had to play 'marble maze' to get it out. Don't do that.
Hole in the lid.
I had previously trashed the exact size bit we needed drilling holes in a blade that was tempered a lot farther onto the tang than I thought for the knife I made triskadekaphile. Don't do that, either. :)
Looking up through the bottom of the hovercraft platform at the engine in its bucket.
Here's the hovercraft running - the red at the bottom is a drapey cloth skirt filled up by the pumped air. It floats around! You can stand on it for very short amounts of time, and float around! Except my balance isn't really quite good enough, and as soon as it tilts a bit, it falls over. (Perhaps I should kidnap one of lyonesse's crazygraceful aerial silks friends, who seem to come with their own fly-by-wire systems installed, to try it out.) Whee!