Scratch built ribs and outboards

E1 Seabird hydrofoil and jet rib
Letting the paint dry on the latest foil before fitting. The ribs I've built take on water, it's just something to get used to, so the steering servo packed up (a cheap one i no longer buy) . Not wanting to spend over £30 on an IP67 waterproof servo from the model shop again, I found one on aliexpress. Ysido and its lP67 waterproof , I was surprised by the quality, the whole case is aluminium, and price £15. Stainless Steel gears and 2 strong metal arms, which I didn't need to use, my futaba arm fit the spline so saved messing around. See pic, they come in 25kg and 35kg.
Whilst it was on the bench I thought it needs attention, so looked what I had, ah back to black from Halfords, it works on the car bumpers so why not. Two coats with a small sponge and a paint brush gave it a nice shine, looks new again .
Correction.....its acrylic graphene trim restorer, expensive but very good,

 

E1 hydrofoil
Flat bottom foil, similar to earlier tries, the idea being to reduce the lift created at the back. Then rely on tilting to create more or less. It looks a bit odd with two extensions, could it have an effect on water getting into the impeller? Only testing on the lake will decide.

 

E1 hydrofoil

Took a while yesterday to get it lifting clear of the water, the answer was to add some negative pitch to the outboard foil. Running into wind seems to give more lift, guess thats air getting under the hull giving some extra lift. I have a few things to try now, like swap the motor for a lighter one, extend the hull to cut down splashing. Stop water entering through the steering port. A different extension to try , along with a stronger foil, it's prone to cracking at the pivot.
Video to follow.

 

E1 hydrofoil
As I was swapping the motor I noticed a lot of movement in the shaft. So stripped it down to find both bearings had disintegrated, so I must have been loosing thrust from the outboard, but it worked well enough. Solution, I removed the part from my other jet outboard, I can make a new bearing holder on the lathe when I have more time. I reworked the steering so there's a new hole as high as it can be, did away with the lever, and put the bellows outside where I can get to it.
I used ally sheet to make a splash guard fitted as close to the outboard as I could get it with down turned edges to keep the spray contained and give it strength. Hugo was right about the weight of the new spacer, it was heavy, so we have a new one to fit, a few grams saving at the back makes a difference.
Next I need to print the stronger foil, then I can be ready for tomorrow's trials, and maybe film part 3 for utube.

 

E1 hydrofoil
Extending the intake doesn't seem to have any detrimental effect, this one has a longer point to the front and just rounded at the back, it will act as a rudder until its lifted clear of the water . Adding 1mm to each foil side seems to have made it a much stronger unit, I've set it with slight down trim as before.
So with decent bearings giving more power, a lighter motor, and a splash guard surely its got to be good, but I'm used to taking one step forward and two backwards.
Nick at the club wants 2 dummy outboards for a lifeboat rib he's building, they can act as rudders. It would have been a huge job to draw them, but I've realised I can scale mine to any size in Cura the slicer. So for fun I printed a 1/4 scale mid section, it came out perfectly and only took 1/2 an hour every screw hole is the size of a pin. The same part at 1/2 scale takes 2 hours, so still not too bad. I will tell him the good news today.

 

E1 hydrofoil
Being jet powered, I get some good tips,from the jet lads, one is to make the rear of the spacer pointed to remove turbulence. Having just printed a new ,lightweight spacer I thought I could print the point and glue it on. The corners of the splash plate have been removed, this gives it a nice shape as well as helping to reduce the lift it creates. On the full size the hull is extended down, almost like another hull has been added, I guess this is to reduce water hitting the motor, thereby reducing splashing and giving a nice transition from floating to flying.
For fun i used my files to print a 1/4 scale outboard, makes a good keyring.
In my flying days you could always rely on a high wing plane being easy to fly and stable, let's hope a a high wing foil can do the same.

 

E1 hydrofoil
From this picture taken from yesterday's video you can see how the splash guard is doing a good job, glad I didn't get rid of it.
2nd picture, when I've had some fun developing the jet version, I can try the prop set up again. On the real machine that foil looks quite vulnerable.
If I can't think how to fix a foil to my existing outboard, then maybe design a dedicated gearbox with provision for an adjustable foil. To help with the torque problems I had last time I've been advised to switch to a sharp two blade prop, makes sense.

 

Lifeboat rib
Spent today on Nicks outboards. I printed my own propellers having not been able to find any the right size. They can be removed from the engines for running on the lake so just acting as rudders.

 

Today's session didn't prove anything startling, but it goes well enough at half throttle. I am printing a huge spacer for next time so the jet outflow will be right out the water.

 

This should be interesting, it's certainly a lot cleaner from a hydrodynamic point of view. The cowl should be clear of the water when sat still.

 

Ready for a test tomorrow, slimmer and half the weight, the hydrofoil not me.......Put the main foil back to the mid position.
Because I've made it 20mm longer I can use the jack plate to lift the whole engine up if needed.

 

E1 hydrofoil
Testing on the lake yesterday, it wasn't what I was expecting, very unstable. It took me all morning to realise what was wrong, I kept noticing a silver stream from the right foil under the water, added to which more spray on that side. So when I moved them forward the right side must have been set at a steeper trim angle. I needed a way to prove it, I decided I needed to hang the boat from it's nose which turned out to be very easy and effective, see photo. With my biggest set square I found the right foil to be 2.5mm further forward. I now have a way to get them equally set up. Whilst hanging I noticed some distortion on the surface, which must have happened due to travelling at speed under water . Luckily I made the sections removable, so it was easy to file and sand then repaint.
I will add yesterday's video, see if you can see what I saw.

https://youtu.be/LiIbwDoU9fc?si=30SmtjKeUnzvXQMb

 

Making progress by reducing weight, lost 750grams so far. Still trying new rear foils, and the main foils are now 50mm further forward!

 

It's getting better and better, small steps but progress!

 

Thanks, here is a quick film.