Crusader.

[bob horowitz]

That is fabulous. You are a master!
Bob

[fweasel]

What a monster of a boat.

[golfito]

Awesome!

[785boats]

Thanks for the compliments guys. I'm happy with the way this one turned out.
Here are some stats.

Scale...1/8
Length... 1170mm ( 46" )
Finished hull weight c/w servo & rudder...2660g ( 5lb 14oz )
9s 6000mah ( 3 x 3s )...1394g
ESC & UBEC ...280g
90mm EDF...600g
Rx...6g
Pilot...25g

Total...4965g ( 10lb 15oz )

Pretty light for this Whale of a boat. I hope she gets up on the plane as easily as the Spirit of Australia did.

[Beaux]

That is one cool boat, good luck.

[785boats]

Thanks for that Beaux.

[golfito]

I wait to see it in operation!
Regards!
Hernán.

[785boats]

Well she had her first test run today.
A dismal failure I'm afraid. It just wouldn't get up onto the plane. Just ploughed through the water. Those front struts pushing a wave of water in front of them.
After discussions with fellow club members, it was decided that the reason is that the drive line of the thrust is a bit too negative & just wants to push the nose down. Added to that, the CoG is too far forward for a canard set up. I knew it probably was, but I can't move the packs any further back. I'll sort something out .
Either by raising the rear of the thrust tube or adding a horizontal stabiliser into the rear of the tube to deflect the thrust upwards & push the rear of the boat down a bit. Or both.
The GoG is my main concern though.
Might even need a bigger fan .

[785boats]

I've had no time to work on this boat until last Sunday
So, I hacked into it & ripped out the fan & mounts so I could move the fan further back in the boat 8 inches to the rear bulkhead.
I also dropped it down to reduce the negative angle of the thrust line. It's now a tad positive which should push the rear down & help raise the nose instead of pushing it down into the water.
That only moved the COG back 1-1/2 inches from the original position. I don't think that will be enough. I might need to add weight to the rear. We will see at the next test. It all depends on what effect the change in the thrust line has.
The rudder may still be a problem, as it had no turning effect at slow speed.

Original position.

003.jpg

New position. 8" further back & lower down to change the thrust line from negative to positive.

001.jpg

[golfito]

What a beautiful challenge !.

[785boats]

Yes golfito. A beautiful old boat. And certainly a challenge.

[785boats]

Well the challenge beat me I'm sorry to say.
The last lot of changes didn't help at all. After a few attempts I just couldn't get it up on the plane. The front struts just plowed through the water & the poor thing wouldn't get up above a fast walking pace.
I finally bit the bullet & decided to take out the fan & put in a normal motor & drive system.

I got started on it a couple of days ago. Finally.
So, out came the fan, ESC, servo & front rudder. And the thrust tube.
The only strut I had that was long enough to reach the bottom of the sponsons from the transom was an old 1/4" one that was 100mm long. I only wanted to run a 3/16 drive line so I put a sleeve in it & a 3/16" floating bush.
The stuffing tube then needed a couple of pieces of tube added to the end of it to fit snugly into the front of the strut.
I knocked up a motor mount from some aluminium angle & that was epoxied & glassed into the hull along with the stuffing tube.

I had a 160mm long rudder but no bracket for it. So, one had to be made.
There should be enough rudder in the water for straight line runs.
So then a 1/8" aluminium transom doubler was cut & epoxied to the inside of the transom.
The strut & rudder bracket were drilled & tapped on to the transom.
A servo rod was fashioned up & installed through to the engine bay. A servo bracket was made up & fitted beside the motor.

The cog is a lot further back, now that I can fit the packs all the way to the back of the boat.
Hopefully it is enough.

The ESC I use for the EDF is a Flycolor HV 150A. It has no water cooling which is fine when it is in the airway of the fan.
But I needed to add a couple of cooling tubes to the finned cooling plate, now that it will need to be water cooled. I had to bend the fins first to allow the brass tube to fit in between them, & then with a liberal application of thermal adhesive the tubes were pressed into place. It should be fine for the short straightline runs the boat will be doing.

I've just got to block up all the air intakes & the exhaust now, & she will be ready for another test.

The strut setup.
002.jpg

Rudder & strut.
006.jpg

Motor & servo mounts installed. Also Epoxy putty around the stuffing tube for added strength.
005.jpg

The 2 x 4s packs easily fit right to the back of the boat now.
006.jpg

The cooling tubes added to the Flycolor HV 150A ESC.
004.jpg

[fweasel]

Knowing what you know now, if you could go back, would you just have left it as it was after the first few test runs on the fan? Or, was that just never good enough and this major revision was inevitable?

[785boats]

After running a few canards I knew that the cog was too far forward. I expressed my concerns in Post #1 & had already accepted that it may need to be converted to a surface drive. I was hopeful that the previous relocation of the fan might be enough. But it was not to be. The cog was still too far forward.
I did contemplate adding about 1/2" of balsa on the front ski to raise the angle of attack. But I didn't think it would raise those front struts out of the water to allow it to pick up speed.
Adding weight at the very rear might have helped.
A larger fan was considered, but would have been inefficient because the exhaust opening of the thrust tube can't be made any bigger. It was only just big enough for a 90mm fan.
So I bit the bullet & changed the fan for the surface drive.

But trust me. The next one I build will be the Hustler, and that one will work with an EDF as it is similar to the Spirit of Australia but with no air intake restrictions.

[golfito]

Following your work, you are a great builder.
I like the idea of the EDF!