Spirit of Australia

[785boats]

As stated over in the 'Bluebird thread', I intend building a few more water speed record boats from days gone by.
a few weeks ago I started sketching up some plans for the Spirit of Australia. I ended up taking a small copy of some line drawings to a copy shop & they blew them up to a length of 42". About 1/8 scale.
I intend to try an EDF first so I ordered a fan with an output thrust of 5.4 kg. i hope to keep the total weight well under that weight to at least give it a fighting chance to get up on the plane.
If it doesn't work, then I'll just add an ordinary 1/8 scale hydro setup in it.
Well it has sort of taken over, & the bluebird has taken a back seat again.
I cut most of the parts out of some 1/16" ply & built them up on a 1/16" ply base, using the dry fit & medium ca glue process.
Once the bacic frame work was finished I added the stringers & side skins.
Then the sponsons were built up.

Yesterday, I gave the insides a coat of epoxy resin & cut the foam blocks for the sections.
Next it is the sponson skins & deck skins.

Here's a few pics.

[Fluid]

I trust that you are using at least a 120 mm fan and 10S; regardless of the weight the wetted area is the biggest "drag" and you will need plenty of thrust to get moving well. You know the importance of ample inlet area/low turbulence ducting and the potential advantages of a slightly tapered outlet.

IMO you will need additional aoa on the sponsons compared to the full-scale boat to get it up on plane. IIRC one of the Bluebirds needed aoa added to its original design before the boat would plane off. With the same amount of thrust the jet racer went from a barge to a record-breaker.


.

[785boats]

The boat was sized around a 90mm fan 0n 8s.
To fit a 120mm fan in there & 10s packs would have meant a bigger boat. It did cross my mind, but I ended up with the smaller boat & fan on 8s.
My biggest concern has always been whether the fan can produce enough thrust to get the boat up over the hump & on to the plane.
The inlets are going to be made slightly over scale size to allow the air intake area to be at least the same as the FSA of the EDF. Possibly a bit larger. Although I don't know how much larger is appropriaste.
I read somewhere last night that on jets with a twin intake, it is best to have a divider all the way to the face of the fan. so I will factor that into the design of the intake cowling too.
The thrust pipe will be made to 100% FSA initially, which tapers it down from 90mm to 81mm. But i am prepared to make a couple of inserts down to 90% & 85% for testing.

Thanks for the tip on the AoA for the sponsons. I can make some wedge shaped ride pads to achieve that. Or, reduce the depth of the rear ski. But that will also change the angle of the whole boat too. We'll see how it goes.

[Scott T]

Very cool Paul!! One of my all-time favourites.

[785boats]

Thanks Scott.
I just love the whole story behind it.

Designed it on his kitchen table.
Built it in the shed in his back yard.
Bought the engine for less than $100.00.
Set a world record in 1978 that no one has been able to break since.

I'll try to do it justice.

[Beaux]

Nice , What type of steering would that have ?

[785boats]

Just a small blade rudder in the center

[Beaux]

Cool, that's gonna be a neat boat.

[785boats]

Thanks Beaux. I've always liked the lines of this boat.

So, a bit more work done over the last couple of evenings.
I fitted the skins on the sponsons.
The side skins first, then the ride pads, then the top skins.
It's slowly coming together.

[Beaux]

The wood work is just awesome, a true craftsman.

[JimClark]

Man Paul you are doing some great builds Paul how bout one of the current boat?

http://forums.offshoreelectrics.com/attachment.php?attachmentid=147263&stc=1

[785boats]

The wood work is just awesome, a true craftsman.

Thanks Beaux. But there are some bits that aren't quite right.
I build by that old addage. "Measure twice. Cut once. Fill gaps". :laugh:

[785boats]

Man Paul you are doing some great builds Paul how bout one of the current boat?

http://forums.offshoreelectrics.com/attachment.php?attachmentid=147263&stc=1

Thanks Jim.
Yes that boat is on the list. I haven't been able to find any drawings for that one yet.
But there are a couple of others I want to build first.
The Crusader is at the top of the list at the moment. I've got drawings for that one.

https://www.google.com.au/search?q=John+Cobb+Crusader&espv=2&biw=1852&bih=889&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiNtNy9yv7PAhWBjJQKHcF2A38Q_AUIBigB

[785boats]

A nice relaxing day today. I decided to make the thrust tube, install the motor mounts, & extend the wires of the EDF to reach the ESC. Then fit it all into the boat.

The thrust tube was made from some 0.4mm ply sheet.
But I had to make a short extension to wrap around the EDF body first, so I could bring the wires out through that & seal them. The whole unit then slides into the thrust tube as it is installed onto the mounts.

The thrust tube tapers down to 81mm as previously discussed. It is easily removable, once the fan is taken out, to allow different ratio thrust tubes to be tried.

The wires of the motor were extended with some #10 gauge wire.

I guess, if I screw the EDF into place, I could give it some juice to see what it sounds & feels like.

I found out today that the motors are made by H.E.T. for the Freewing EDFs so it should be a good power plant.

The extension ring. The motor wires extended & brought through the extension. Just needs some sealant around the wires now.
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Thrust tube & EDF mounting blocks.
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All sitting in place.
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Side view.
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[srislash]

Nice work :buttrock:.

[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:biggrin:

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.

https://www.youtube.com/watch?v=nCIOTVIl31M

[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.:lol:

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.:Praying:

[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.
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Installed in the boat. And the servo too.
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Skins all fixed & trimmed.
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A messy transom.
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Much nicer.
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[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.
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View from the underside.
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Inlets all cleared out. They are eggshell thin.
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[Fluid]

How do the inlet areas compare to the fan area?



.

[785boats]

Hi Fluid.
The Total area of the inlets is 6926 sq mm
The SFA & thrust tube outlet area is 5138 sq mm.
The total area of the 90mm fan is 6358 sq mm.

So the inlet area is nearly 24% larger than the SFA

If I had made the inlets to scale, the total inlet area would only have been 4752 sq mm.
I hope it can suck enough air in to get the thing running.

[boredom.is.me]

Just remember to keep it smooth

[785boats]

You betcha buddy.
I'm working on that now.
All of the foam has been removed & I'm working on the curved inlet lips as we speak. I mean 'type'.
then I'll lay another bit of glass cloth around the inside of the inlets, & paint the whole inside with resin up to the fan.

[boredom.is.me]

A bit late to wonder/mention/ask, but have you ever thought of dissolving the foam with a solvent? Maybe acetone or something? The feasability and effectiveness of that method is just something I've always wondered about.

Almost there though. I can't wait to see this thing go.

[785boats]

That was my first thought too. But Acetone didn't even look at it. The foam blocks are high density polyurethane I tried laquer thinners too. Nothing.

The rudder arrived yesterday so now I can install the pushrod through the transom in the right spot & then cover the last of the cowling frames, & add the tail section. Then it will look like the real thing.
But it's our last day of racing for the year tomorrow, so I've got 4 boats to prep for 4 different classes tonight.
And some new batteries to cycle a couple of times.

Here's the finished cowl with the rounded lips.
Just a bit more sanding & smoothing, then a coat of resin to finish it off.

147502147503147504147505

[TheShaddix]

I've been reading up on these boats. Very inspiring to say the least. The guy had no money yet managed to somehow achieve speeds that no one can beat to this day. I can see where you get the drive to do all this work and recreate these legendary boats. Some day you might want to get an actual jet turbine and build one of these in a slightly larger scale.

[785boats]

There are some inspiring & tragic stories in the pursuit of the water speed record. But I'm not brave enough to try this. Or rich enough.:sad:
I doubt that you can get an airforce surplus jet engine for $69.00 any more.:laugh:
But speaking of "Pursuit", check this latest effort from a British team to win the title back. The Pursuit 350. What a drop dead gorgeous rigger. I'd like to make one as an ordinary prop rider to race.

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[TheShaddix]

Oh, I was talking about building an RC boat with a jet engine (jetcat turbine), a bit larger in size than what you're building now. Can't seem to find that boat you mentioned.

[785boats]

Sorry.
I thought you were referring to a full size effort:laugh:
Here's a bit of info on the Pursuit 350 project.

http://www.britishpursuit.com/

[NativePaul]

Haha 350, or OSE? Steven needs to change his font to take advantage of all the free advertising when this starts making passes.

[Fluid]

So many flashy designs, so much hype, so many sponsors, so much BS...

http://forums.offshoreelectrics.com/attachment.php?attachmentid=147520&stc=1

http://forums.offshoreelectrics.com/attachment.php?attachmentid=147519&stc=1

http://forums.offshoreelectrics.com/attachment.php?attachmentid=147518&stc=1

http://forums.offshoreelectrics.com/attachment.php?attachmentid=147517&stc=1

http://forums.offshoreelectrics.com/attachment.php?attachmentid=147516&stc=1

[NativePaul]

LOL at the big black one, Cobb died in a rear sponson canard, Campbell died in a forward sponson hydro, I will make a mid sponson hydro and live forever!

[785boats]

Fluid.
It's true, there have been many projects started & just haven't come to fruition. Usually through lack of sponsorship money. It's always about the money.

Paul.
John Cobbs' Crusader is the next one I will be building after this one. Yes it killed him. But I just love the look of the thing. And you know I love canards. So it's compulsory enjoyment for me.

For those that aren't familiar with the boat.

https://www.google.com.au/search?q=John+cobb+crusader&espv=2&biw=1600&bih=885&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjusu3t9qPQAhUGF5QKHXphBAQQ_AUIBigB

[Fluid]

Back to R/C boats: this reminds me of the chase for the fastest R/C boat. Set high by Joerg years ago, many tried to even match it. Lots of claims, LOTS of $$$, and finally someone beat it by a couple mph. Only then was Joerg compelled to defend his record. We all know how that turned out.....

I really want this build to succeed. I doubt it will be nearly as fast as a conventionally-driven boat of this size or power, but that isn't the point. This is about recreating a classic WSR boat down to the air-driven propulsion. Get busy and put it on the water!


.

[785boats]

Thanks Fluid.
I'm going as fast as I can. No one wants to see it work as much as I do.
For sure I'd be surprised if it aproached the speed of a prop driven boat. But as you say, it is all about replicating the original as closely as possible. I'm certainly not after any records.:laugh:
If the fan gets fully loaded up, the calcs say that it will be pulling about 3600 watts. We'll see.
That old saying comes to mind. "Hope for the best. Prepare for the worst".

Well. I'm heading off to the lake now, for our last day of racing for the year. I'm contesting 4 classes today. The pressure's on! Ha! Ha!

[NativePaul]

I would have thought your racing season was just starting not finishing like us, you stop for the summer because it is too hot?

[785boats]

That's part of it Paul.
It gets very hot here in the sub tropics. Our clubs' racing season starts in late January & runs through till now, mid November.
We don't have a real 'winter', here & the weather is usually pretty good through the middle of the year.
Plus many people go away for holidays through the December/January Christmas period.

[Shooter]

Amazing project! Very impressed. Can't wait to see it on the water, or even the grass again!! :laugh:

[785boats]

Thanks Pete.
I don't think I'll run it on the grass again. There were some rocks up near the end of that little run & they scratched up the ride pads a fair bit. Took the edge off one of them.
No biggie. A bit of auto body filler will fix it.

[NativePaul]

Nice, I'd love a 10 month racing season we only race half the year here, April to October.

[NativePaul]

Nice, I'd love a 10 month racing season we only race half the year here, April to October.

[nobbiworld]

147563

[785boats]

Beautiful picture Steve.
I get the hint. I'm still doing bits & pieces on the Bluebird at the same time.:biggrin:
But this one has just sort of taken over for now.

Paul.
That's too short.

[785boats]

A few pics of this weeks' progress.

Some stringers & balsa added to the bulkheads for the cowling plates & the tail fin. Bottom of the cowling plates epoxied on.
The gap between the 1/4" stringers at the top is for the tongue of the vertical fin to fit into.

147774

Carbon pushrod tube & rudder mounting plate.

147767

Clamping the tops of the cowl plates of the first section

147768

Fin pieces & wing with lightening holes from 1/8" ply.
Note: the holes in the fin pieces don't line up with each other in an attempt to maintain strength.

147769

Fin pieces epoxied together & wing mounting brackets glued & screwed to the top of the fin.

147770

[785boats]

Balsa added to the sides of the fin & the top of the wing & roughly shaped. Then the wing was epoxied to the top of the fin.

147772

Sitting in place.

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Fom the top.. Just the balsa to add to the bottom of the wing, & shaped.

147773

[Doug Smock]

:beerchug:

[Beaux]

WOW!!!! Very nice!

[TheShaddix]

This is some amazing work, man. I got nothing but respect for it. I am sure everyone, including myself, is super anxious to see this on water! I don't recall anyone has ever done something like this before.

[785boats]

Thanks for the kind words & encouragement guys.

Shaddix.
I can assure you, that once I get the hold down bolts for the cowling sorted & the hull sealed & primed, it will be getting wet.
I need to know if it works or not before I bother with the painting & detailing.
I just need to streamline the transiton from the inlets to the fan, inside the cowling.
I'm adding a bit more foam in there & will carve it to shape. But I need to leave room for the batteries & ESC too.

I received the ESC the other day that I thought I might try. It is a Flycolor HV esc for agriculture drones. No water cooling but the fins will be in the air duct.
They will be easy to add water cooling to for ordinary boat use too. We'll see how it goes first. If it is not up to the task I'll rob a Swordfish 240 out of one of my other 1/8 scale hydros.

http://www.ebay.com.au/itm/Flycolor-waterproof-150A-HV-Brushless-ESC-support-5-12S-for-Agricultural-Drone-/291873009188?_trksid=p2141725.m3641.l6368

I'm just fitting the ski at the moment.

[TheShaddix]

That's cool! You could always just epoxy a few brass tubes in between those fins. I did that on a seaking 180 esc. Or just get a watercooling plate on ebay and attach that instead of the fins. I am working on a few projects here as well so I always check this thread for inspiration. I like that this boat is made of wood too, makes it more special.

[785boats]

That's cool! You could always just epoxy a few brass tubes in between those fins. I did that on a seaking 180 esc. Or just get a watercooling plate on ebay and attach that instead of the fins. I am working on a few projects here as well so I always check this thread for inspiration. I like that this boat is made of wood too, makes it more special.

The brass tube was my thinking too. The cooling plate is part of the splashproof case so I don't think removing them would be very easy, without destroying the spashproofing.
Wood is my favorite material for building boats.

I've added the rear ski & given the hull a coat of sealer.
I also added a piece of foam to the underside of the cowling, & carved it out, to offer a smoother transition from the inlets down into the hull. There was just a sharp 90 degree shoulder there before.

[785boats]

A couple of coats of sealer. Some filler Some high build primer putty paint. A lot of sanding, & copious amounts of Mercury cider, and she was ready for a coat of white primer.
Isn't it amazing how once you get it painted white & out in the daylight more little cracks & gaps in the joints show up.
It looked perfect in the shed at night under the lights.:olleyes:
I'll rub this primer back, fix any imperfections, & give it one coat of gloss white then take it for a run.

[grsboats]

Sweet....congrats Gill

[golfito]

I was impressed!

[TheShaddix]

This looks amazing! Super clean lines.

[785boats]

Thanks guys.
Unfortunately the weather turned stormy yesterday afternoon with rain bucketing down, so I didn't get to paint the gloss coat.
Hopefully it will be fine today & I an get it done.
I remember reading somewhere that an EDF boat needs at least a 1:1 thrust ratio.
The stated max static thrust of the EDF on 8s is 5.4kg. The boat as it stands now, ready to run, is 4.37kg. That's about a 1.2 :1 thrust ratio
That allows a 20% margin for losses. I believe most of the losses will be in the intake ducting. Hopefully it will stay below 20%.

I don't think I've ever been more apprehensive about a maiden test, than with this boat.

[boredom.is.me]

So close!

[785boats]

My computer is not working properly so I am posting this from my phone.
She had her first test runs a couple of weeks ago.
It ran well, even though not quite fast enough.
I can't post links from this phone, but if you go to youtube & search for 'bensboat', Pete has posted a couple of videos on his channel.

I've since made a smaller thrust tube and that has increased the thrust from 4.04kg to 6.2kg.
Without the cowling installed the thrust went from 6.1kg to 8.2kg.
So the inefficiencies of the cowling loses 2kg of thrust.
We always knew it would be a problem, even though I made the openings 20percent larger.
The boat runs at what I consider to be the perfect speed without the cowling installed.
No video unfortunately.
So I intend to cut some cheat vents into the cowling to allow more air into the edf.
I will make sure to get some video of the next session.
A bit more speed & I will be satisfied.

[golfito]

I took the audacity to upload some of his videos.

I did not resist the temptation to see them ...
Thanks.



https://www.youtube.com/watch?v=l4Knwj4JNnI

[golfito]

https://www.youtube.com/watch?v=mddIcO3enhY

[golfito]

https://www.youtube.com/watch?v=D0Ogk3wQMjk

[Fluid]

Great job Paul, it performs better than I expected. Gorgeous looking on the water.



.

[srislash]

She's great. Seems to run well in the rough too so far. But that always gets worse with speed, it may stay good though as it runs over the water rather than using the water for propulsion.

[785boats]

golfito.
Thanks for posting the videos.

It was a pity that the signal kept cutting out but that was because the receiver was crammed in amongst the battery cables & the esc. That's been fixed now.

Fluid.
Thanks. It will look better with the paint job finished & the graphics all applied

srislash.
I'm glad to say that it was running fast & stable when I removed the cowling. It even cornered fine at the higher speed.

[golfito]

:thumbup1:

[TheShaddix]

This is great! I am sure you can fine-tune it from here (more power...), the overall design works and it sounds super cool.

[romspacenut]

Very nice build 785boats. I think I know what I want to do for my summer build. I have Kolibri micro turbine that's been sitting around that I think may work.

[Shooter]

I love this thing!!! ......and that sound!!! :thumbup:

[785boats]

The Shaddix.
I'm in the middle of cutting out the section between the two intakes at the moment.
So I'll connect it to the fish scales again and see if the thrust improves much on 8s. I'll also try 9s to see what happens. We'll get there one way or another.

romspacenut.
A real jet engine would be most impressive indeed.
Google the 'Hustler'. Similar hull but with no inlet cowling to cause any losse.

Shooter.
The video doesn't do the sound real justice. It really is a lot louder in real life.
But yes it does sound a lot different to what we are familiar with.

[785boats]

Had a couple more runs on Sunday with the following changes made to the boat since its first outing.
Reduced thrust tube.
Extra air intake opening between the main intakes.
Increased angle of attack on the sponsons.
Increased cell count to 9s.
12mm cut off the bottom of the rudder.

I'm happy with the speed & setup now. Time for some decals & detailing.

Here's a couple of videos.

https://www.youtube.com/watch?v=bdzXi0rdAAs

[785boats]

https://www.youtube.com/watch?v=JTF5U_SYHn8

[785boats]

https://www.youtube.com/watch?v=tSYiqVSnT2k

[JimClark]

That looks great can't wait to see it finished.

Sent from my Moto G (4) using Tapatalk

[golfito]

Excellent congratulations.

[785boats]

Thanks guys.
Jim.
The finishing off part is the part I like the least.
I'm already working on the next boat in the group.
But I will make a concerted effort to get this one finished.

[RandyatBBY]

Congratulations, I would say you did well. Considering everything it preforms well. Great effort.

[785boats]

Thanks Randy.