On this sunny Easter day I got a chance to head out and test the hovercraft in a parking lot.
Thanks to all the help from Jenny, Wim, Amy, Adrian, Ayse, and Lars!
Everything prepared to go in the morning
Adrian came over early and we loaded the hovercraft into the trailer. The upside down hand cart worked well. The two of us were able to load it without a significant challenge rolling it up the ramp.
A freshly loaded hovercraft
After loading up hovercraft we headed out for the Redwood City Port Boat Launch
The trailer about to leave the driveway carrying the hovercraft.
Arriving at the Redwood City Port Boat Ramp
The launch permit for the day.
After a break for brunch we returned and rolled the hovercraft out of the trailer. And tried it out.
We started testing travelling using the docking lines. And it hovered for over a minute. And we crossed the puddle uneventfully! Here's the view from the trailer.
Unfortunately if you listen closely at the end the lift propeller fell off again.
So we found the right wrenches again and disassembled the lift engine again. I had tightened the bolts pretty hard but I guess it could have had more.
Unmounting the engine in the field
The propeller collet after falling off the engine shaft.
There was only a little scuffing on the bottom of the blade this time. It didn't fall all the way off the shaft as it hit the deflector baffle for the skirt.
We got started reassembling the engine and decided to use a larger wrench to make sure the bolts were tighter. However the 15" wrench handle prooved too strong for the collette bolt. See below...
The broken bolt
Unfortunately this brought the test to an end since the other half of the bolt remains in the collet and there's no way to secure the collett securely anymore.
I think I need to find a new mechanism for securing the propeller.
I've successfully covered the rudders with shrink wrap. They look pretty good.
Two shrink wrapped rudders.
I've still got quite a bit to learn about how to effectively use the shrink wrap gun. But I only had to redo one of the rudders.
The first one I took longer to do.
You'll note that I spent more time at a distance and definitely burned some holes. I also tried to adhere the edge using heat bonding. However it was problematic as I was pushing against the open part of the frame, thus couldn't get much pressure between the pieces I was squeezing.
Results of first attempt to shrink wrap a rudder
A close up of the burn hole, and some of the edge attachment
Where the bolt ends pierced the shrink wrap
At the other end, 2/3 bolts burned through.
I tried again on the 2nd rudder. This time I clipped some holes for the bolts first and ran tape over the ends. I also used the shrink wrap tape down the trailing edge and over the ends with the hopes of getting a smoother surface once shrunk.
Taped edges visible with bolts cut through early.
Here's how it went:
The results were notably better. With a few caveats. Clearly the tape worked better, but there's still some curling up at the edges of the tape.
Overheating at the ends, but bolts are much better.
And I clearly discovered that applying the tape down with full pressure is important. I missed a few inches that were not pressed down well, and consequently the stretching pulled the adhesive apart before it could fuse. (I probably also heated the front edge first too.
A tear where the tape was not adhered well enough.
But I was able to patch it over relatively easily with another strip of tape, and a quick heating by the heat gun.
I patched the tear with another layer of tape and tensioned it again to look like this afterwards.
I cut the shrink wrap off of the first rudder and tried again. The biggest difference I note is that I'm more confident. I move more quickly at closer distances. And the other thing is that the wrap shrinks when cooling, not when hot. When it's hot it's actually softer. So when applying heat, you don't apply heat until it's taught. You apply heat quickly and then move on. After it cools come back and check on it, and if it's not tight enough re apply heat. Continuing to apply heat to an area basicaly melts it and or burns it.
Here's my 3rd attempt.
The results worked out well. I used the above quick heating and trust that it will shrink later. As well as I trimmed more of the excess film away. And I taped at the trailing edge, and made sure to apply the tape firmly and press the edges down hard against the frame underneath instead of taping where there was an air gap.
