Spirit of Australia

[785boats]

Thanks for that.
I'm taking it up to our club today. It's our last round of 1/8 scale Hydro races for the year. There's a guy there that used to build & fly large model jets with real jet engines in them. He might be able to give me a few pointers.
We might even fire it up under his watchful eye.

[785boats]

Well a bit of fun yesterday at the club.
We gave it a test run on 4s first to check for vibrations. The sales pitch on the EDF stated that it had been dynamically balanced, & it did seem to run as smooth as silk.
So I hooked up 8s & spun it up on the table. Man it had some thrust.
So then some idiot suggested I give it a run on the grass. Well, idiot or not. I always follow my own advice

In the video I only gave it about a 1 second burst. And the thing just keeps sliding over the grass. Grass is fast. I know water has a lot more drag, & it won't take off or run like that. But still, it was good to see it run.

[Beaux]

Wow now that was cool, might have an idea for an air boat.

[TheShaddix]

This is a very exciting build! Looking forward to seeing it on water. I'm sure once the thing gets on plane it'll glide nicely. And the sound it makes is awesome. My only concern is what happens to the fan when the boat flips and it's exposed to water? Will it still work afterwards?

[Fluid]

No different than an outboard as far as the motor is concerned. But if it is at full speed and invests much water the blades may fail. I met a guy who made an edf hydro but smaller and with lower power. He had trouble making it run until I suggested moving the CG forward. Now it runs decently and can flip, but not nearly as fast as a water prop would run, In several clips only one damaged the fan blades which are easily replaced.

[785boats]

This is a very exciting build! Looking forward to seeing it on water. I'm sure once the thing gets on plane it'll glide nicely. And the sound it makes is awesome. My only concern is what happens to the fan when the boat flips and it's exposed to water? Will it still work afterwards?

Thanks for the compliments /shaddix.
But what do you mean 'when' the boat flips. I'm sure you meant to say, 'If' the boat flips.

It has been playing on my mind too, about the water in the EDF.
As Fluid stated. Not a problem for the motor.The blades might be a different story.It's also one of the reasons I opted for an aluminium body for the EDF. I've read about nylon or f/g ones shattering when the blades let go.
If it does a back flip then I will have half a chance to get off the throttle & the revs should drop a bit before it gulps down some water. But at least the blades won't be driven when the water hits the fan.
A bigger concern, I think, is if the back lifts & it nosedives. The water will enter with the fan being driven at full throttle.
This is all assuming that the thing gets up to a "flipable" speed in the first place.

[785boats]

Time for a catch up of the last few evenings effort.
I made up some ply blocks with a 5mm nylock nut epoxied to the underside for the cowling hold down bolts & epoxied them into position.
Then the servo was cut into the side frame.
Now I could fit the top deck skins. The two outside ones first & then the center panel. This one was a bit of a problem because ply doesn't want to bend in two directions at the same time.
But I got it pretty close. It just needed a bit of filler along one side to make it look right.
Then I added a piece of 0.6mm ply the the heels of the sponsons, & the transom to cover all the ends of the stringers & the two 25mm holes that I accidentally drilled in the transom when I was drilling all the other bulkheads.

The cowling hold down blocks & nuts.
002.jpg

Installed in the boat. And the servo too.
003.jpg

Skins all fixed & trimmed.
009.jpg

A messy transom.
005.jpg

Much nicer.
010.jpg

[boredom.is.me]

She's really taking shape now.

[785boats]

Thanks.
Out of curiosity I just weighed it.
bare hull c/w servo, 1450g (3lb 3oz)
Hull complete with EDF, thrust tube, ESC & 2 x 4s 6000mah packs, 2985g (6lb 9oz)
Pretty light so far.
Hopefully I can keep the cowling & tail section nice & light too.

[785boats]

Not much to report over the weekend.
I started on the cowl & air intakes.
It is carved out of some polyurethane blocks. I will just cover it with some glass cloth & then carve out most the foam, leaving some for floatation.
Here are a couple of pics in a roughly shaped state. A bit more fine sanding & shaping to go yet.
They look a bit strange, because the inlets are 10mm wider & 10mm higher than scale to allow for the fan area.

[Scott T]

Work of art Paul!!

[fweasel]

Work of art Paul!!

No kidding. This post seems less about RC and more about sculpture. Amazing work so far.

[785boats]

Thanks guys. I'm glad you like the look of it.

Here's another old boat that I have to put on the list of boats to build.
Looks pretty simple to build. All square lines & flat panels except for the cowling. But even the cowling would be relatively simple.

[785boats]

I finaly put a layer of glass on the cowling. I mixed up a bit too much resin so I gave the cowling for the Bluebird another coat of resin while I was at it.

Then it was time to start gouging out the foam.
The inlets are very thin & flexible as I only used one layer of 128g cloth.
All I plan on doing is adding another layer around the inside of the inlets.
I need to form some rounded lips for the leading edges first. A ring of balsa should do the trick there.
It only weighs 140g at the moment. That's pretty light at this stage.

All glassed up & the removal of the foam has commenced.
m_032.jpg

View from the underside.
m_033.jpg

Inlets all cleared out. They are eggshell thin.
m_034.jpg

[Fluid]

How do the inlet areas compare to the fan area?



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