Scratch built ribs and outboards

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E1 Seabird
I put the partly painted foil together to show Paul at the club yesterday, he was impressed. I got the jack plate working, it ended up being able to move twice as far as I thought it would, about 36mm . Also found an adjustable way to connect the steering arm, see photo. I didn't want to disturb the steering servo as I glassed its mount in the boat, and I want to be able to return the boat for normal use, so with it being high up I am making a vertical pivoting arm about 70 mm long. Then the steering arm can exit near the bottom of the hull.

 

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To have a break from painting I made the parts which bring the steering arm very low down. This is needed to allow the boat to rise up about 2 inches from the water.
At least that's the plan, I am relying on speed to get this boat airborne as its very heavy.

 

[Unusual RC]

When I was kitesurfing a hydrofoil board, it amazed me how low the "take-off" speed was.
Even with very low power from the kite (you could ride 2 to 3 kite(sail) sizes smaller compared with a normal surface-planing kiteboard)
Top speed was over 30 knots, so no low speed foil!

As far as my knowledge goes, the craft could self-lift just by speed.
You do not need to use control surfaces to do so.
Nevertheless some kind of trimming is necessary for sure.
Being able to do that from the Tx is a big help.
Not linked to a control lever, rather a dail (as I have for my vertical trim of my jet-drive)

 

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That's encouraging, after all the full size will be no lightweight
Had a full day in workshop today, got these hydrofoils fitted, then put another outboard on my F1, and a stronger mount on my jet rib.
The F1 engine was designed to be short, unfortunately that made it weaker, so coupled with high speed runs, a few cracks appeared. I could have kept running it, but as I had another engine to hand I decided to make the change.

 

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E1 Seabird
I chose the original E1 logo because it has straight lines so nice and easy to cut out. Both foils painted now, so no excuse, I need to decide where to put the hole through the hull . Because the hull lifts out the water I need to bring water cooling from the outboard to feed the esc. The pick up in the hull is sealed, but can be used if converted back to a normal jet boat. We need to film the maiden run, even though the chances of it working first go are near zero.

 

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E1 Seabird
Ready for a first run, fingers crossed. I adapted a carry base for it with slots to accommodate the foils. I won't fit the cowl until some tubing arrives from China to connect the water to the esc, I used what I had. Might have another try at getting the base of the foils square after having a run on the lake. Might try body filler behind them, pulling them gently on the screws till it sets. If the base is not square, it throws the foil out when tightened up.
So wish me luck for Saturday.

 

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E1 Seabird jet outboard
OMG it actually works. I ran her gently trimming for straight runs, then gave it half throttle and up she popped. OK there was far too much spray due to the intake on the jet outboard. Also increasing throttle made the nose drop, so I had some fun at half throttle and tried a few adjustments on engine height and trim angle. None of which was an improvement on the first run. There will be a video soon, but to start here are some stills from the video.
Where next, I think it's worth trying a prop outboard, if only to cut down on the spray, so watch this space.

 

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Ready for round 2, this is the engine that had a brief go on the f1, then had its gearbox serviced so no excuses. It looks like it could lift the prop out of the water, but there must be a balance point where the prop stops driving and settles back. It's a lot more streamlined than the jet version which can only be good, but what about torque from the prop, that could be an issue, it doesn't seem to bother the full size version though.

 

[Unusual RC]

As far as I can see the original scale boats can only trim the outboard angle. Not sure if they can trim the height of the outboard from the cockpit too!
Since you are pioneering again here you will have to find the sweetspot!
I guess prop torque on small scale is a bigger factor than in big scale.
Looking forward to your new attempt!

 

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we tried the prop outboard yesterday, and it was a struggle to get a similar result. By the end of the morning it was nearly as good as the jet outboard version. So Paul (camera man and hydrofoil expert) thinks I should go back and use the jet with a new intake and adjustable foil. No idea how to do it yet. He thought the outboard was so powerful that it was overwhelming the main foils, along with torque steer. There was quite a lot of porpoise motion going on too.

 

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E1 Seabird
A few hours today drawing a new streamlined pickup, it has an adjustable foil on the front, just 2 screws to alter the angle.

 

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After getting the green foil made up and painted, I realised its a 2 minute job to change foils at the lake. Just pull out the 3mm ss pin and remove 2 screws. So I drew up another, quite a bit thinner, it's still in primer. This will be great for trying different sizes and shapes, and being able to change its angle too will help.

 

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this project has been made possible by already having developed my own outboards. The pickup is held on with 4 x2mm cap head screws, if I could find some longer than 30mm I could add a spacer, then I could get the engine higher and keep the foil where it is.

 

[Unusual RC]

The green one has a high lifting foil profile!
With a propeller outboard this one could be much slimmer (water is over 800 times more dense then air)
For the jet, where the inlet does create force downwards due to suction/acceleration of the column/mass of water, this might be necessary.
Your quick swap-out method might proof to be very useful tor this development!

 

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E1 Seabird
Thanks Michiel, I have ordered some 50mm long screws from China, so I can add a 20mm long spacer, between the pick up and the chamber. That means I can lift the engine up 20mm and maybe reduce some drag as well as getting the cowl out of the water at rest. I see your point about the green foil having an aircraft type profile, guess that's cos I've spent more time on model planes than boats. I will try it anyway now its made, and the slimmer one too. Then follow geek midget with a slim and shapely version, should be fun trying different shapes and sizes.

 

[Unusual RC]

So much to test!
Carry on I would say
This can be a very interesting new type of RC racing-boat!
Even in Japan a model enthousiast picked the E1 series up as you noticed!

 

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E1 Seabird hydrofoil
E1 Seabird hydrofoil
Mixed result today, as I forecast the foils were way too big. Steering was affected too , so I've moved to a smaller foil and placed it further back. Hugo will be pleased to see I've shaped it best I can for speed through the water. I've also allowed for more movement in the tilting angle. Finally it now has a sharp front edge. Just need to draw up that 20mm spacer ready for the screws coming from China.

 

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E1 Seabird hydrofoil
This is the new foil for Saturday. It reminds me of a shark with its mouth open from the front, guess that's no bad thing. It pivots well giving a good range of settings. Hope the steering is improved too from Wednesdays foil, speaking of which David at club said try cutting it down so I have chopped 20mm off each side. It gives me something else to try , but my hopes are pinned on the great white

 

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It was so cold and windy yesterday, so not good for making changes at the lake side. It did work but not as well as I thought it might. I really need to get that spacer fitted so the exit from the jet is into air rather than water, though its hard to see with all the spray. There's a new great white coming for next time, stronger, meaner, sleeker, and a little bigger. See photos, the printed foil has come out 10 times better by tipping it on its back and printing vertically.