With the new collet installed I then moved onto testing the engine. Since I was on my own you'll see that I rigged up some eyes in the walls of the garage and secured the hovercraft from moving significantly laterally.
Here's my first flight.
Everything went relatively well but there's some ominous rattling near the end. It's easier to notice now that I listen to the recordings. But what do you do after a successful test? Try again...
Yeah, not so good. It was clearly not doing things properly since it didn't even start hovering. And by then it had been loosened so of course it fell off again. But it's nicely contained in the housing.
So I took it all apart again. Measured that it hadn't worn more than a few thousands off the bushing, and put it back together again. This time I put more than the recommended 95 inch pounds, but not excessively. But then I ran a very short test:
It hovered well, but I took it apart anyway and there was an extra quarter turn I was able to get out of the tightening bolts. So I tested again.
This time I throttled up a bit and everything seemed ok. But I took it all apart and was able to tighten each bolt a quarter turn again. So one more check.
Things sounded better, and the bolts did not have freedom when I took it apart. So I decided to try again.
Everything sounded good and it was hovering very high. I've had some balance issues so I tried adding some weight at the front to feel the balance. It was riding super high and super stable when I throttled up. However as I throttled down to feel it settle, the propeller started hitting the underside of the engine as it had slide up the shaft during the testing. That's what made the horrible noise at the end.
So I'm a little frustrated now...
I think that there's some work to be done. Leveraging the keyway seems like a good idea. And also using the end of the shaft, and the end bolt would make sense. This is the mounting technique for most lawn mower blades.
