Hi. I've just joined and, well,the

[Testpilot__]

Hi. I've just joined and, well,the technology with foiling yachts is right on the edge of developing technologies, I'm a commercial pilot and designer of an offshore foiling catamaran. This forum will have the mindset for experimental, and concepts, so any interested feedback is most welcome.
I've built a small scale working prototype, but I'm pondering the larger scale design now. The sailing catamaran boat will be approximately 60', 25 ton. Thought I may consider the second prototype to be 1/2 scale. Just for practical construction reasons, proof of concept etc. The area I'm concentrating on at the moment is the canting foils deployment. Much like AC75 America cup boat has. However my design is not for racing, where hydraulic systems are probably stripped down after every race, but more long term offshore cruising. Tacks will be of long duration, and the load on the foil(s), 2 x on starboard, 2 x on port side, will be mainly a static load. (I've gone for a canting foil, as I'm trying to maximise the righting moment)... Set the foil position and crank on the sail power, plus twin prop thrust (electric) to help get to foil speed. Once the catamaran is foiling, the loads will reduce, though I think design parameters for around 20 ton load on the individual foil arm would be not out of the question.
I've been looking into hydraulic assist heavy duty steering box type of arrangement. I know they have a worm drive and I want zero backlash in the application. I'd like to turn a big wheel, and the pitman arm, connected to a tie rod to similar lever on the foil arm shaft, will, for example, raise the port rear foil and lower the rear starboard foil. And then there is a way to lock that position.
I thought an engineering forum might be helpful. So, I'll see if there's some helpful information out there? Thank you!

 

[Sparweb]

Welcome aboard. Mind you don't step in the sump.
I enjoyed watching the AC75's race last year. But all I can personally handle is a Sunfish dinghy.

 

[rb1957]

are you thinking of the AC75 foiling legs, or the F50 foiling "center boards" ? I think the latter may be more practical, but hey, it's your idea ! run with it !!
on a "cruiser" boat ... maybe have a small prop to provide power to the hydraulics ? maybe a small outboard, so you can lift it when not needed ??

you may find more joy in the "engineers with hobbies" forum.

another day in paradise, or is paradise one day closer ?

 

[Testpilot__]

Thanks for the reply. Ac50 dagger boards are practical, but then, I'm going for extremes, the catamaran may weight 30 ton.extreme righting moments, maybe even streamlined battery pods on the foil arms.Bit of extra ballast aarrgh yes As in AC75 foil arms. You know they weight about 1 1/2 ton lol and yes regenerate power from the props most definately, and lots of solar. Thanks for the engineering hobby tip. I'll check it out.

 

[Ng2020]

What are the consequences of various types of failures, either of the hydraulic control system or structural failure of the control surface itself? Rapid capsize?

 

[Testpilot__]

It's a challenging scenario. Over engineering, redundancy, etc. Like all engineering problems. My question is only about deploying the foils, and if steering box type system is something that has any practical application?

 

[WKTaylor]

TP...

For all elements related to marine and electrical, mechanical, hydraulic systems, engines/electrical-propulsion, APU-power, solar, stabilization, etc... I strongly suggest you make sure to acquire the entire SAE 'specifications package' for marine/related specs.

AND if You intend to go 'digital twin' for design-build-test-manufacture-simulations there is a lot of emerging practices, procedures, etc in corresponding documents worth working with.

AND, I'm sure, there are applicable US Coast Guard regulations... navigation, safety, structures, etc... that are unavoidable... and universally accepted world-wide.

Also, be aware these type vessels will likely be subject to constant oceanic marine-life/creature and inert-debris impacts... which only get more severe with high speeds... which may require forward-arc-facing sensors for surface/subsurface debris monitoring along the projected direction of travel.

Hydrofoils will need anti-fouling and impact-resistant coatings/materials to minimize anticipated damage and fouling of the hydrodynamic elements.

I'm assuming you intend [at least initially] for these vessels to run-fast in fair weather and relatively smooth sea conditions... and avoid cold water... AND/OR... is this vessel really intended for fresh-water inland seas [giant lakes]?

I have to stop over-thinking-stuff.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[Testpilot__]

Thank you for your overthinking Wil. It seems to encompass the concept with invaluable points. Yes, ocean fair weather application for full potential. And inbuilt design stability features for less than ideal foiling conditions. Why is cold water a bad thing? Ice bergs? Thanks again. Regards Sam

 

[WKTaylor]

Everything becomes harder in the cold and associated weather: cold-rain, snow, ice, high pressure water-spray, human factors [maintenance, fueling, sailing, navigation, etc]… and repairs to composites... etc.

As an aviation materials and field service engineer, I am very concerned by ambient temperature extremes... Extreme heat and extreme cold.

Extreme heat has challenges... but... as I've learned the hard-way... extreme cold environments are more treacherous in many insidious ways... too many to list here.

Of course aircraft can see environmental extremes of highs and low in one flight. My jet was designed for ambient temps of -65F to +160F... but testing and field experience has forced me to expand considerations ambient temps of -100F to +180F. Factor in Turbine engine high heat/sonic exhaust on a hot summers day in the Saudi desert parking ramp... and deep chill over the arctic at 525-Kts @40K-Ft at night... Ugggggggggg. Reliability at extremes is critical.

But ships chugging along within 4000-Km of the equator... specifically north or south edges of the ITZC... have a significant advantage of narrower WX extremes.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[EdStainless]

I have worked with some commercial ferry operations on metallurgy.
Both 15-5PH stainless for foils and AL-6XN for hydraulic lines.
The Japanese are fun to work with, they want the best solution.
They are very hard to convince, but cost doesn't matter much.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Testpilot__]

Thanks again Wil. You have bought up the global issues faced. Duly noted. I wish I had a jet lol. and Ed stainless. The Japanese. Good to know. AC75 foil arms weigh about 1 1/2 ton. Multiple laminations of profile cut 20mm cold rolled or equivalent high tensile steel on edge. Then you wrap it up with some prepreg or whatnot. Doesn't sound too challenging.
My original question is about raising and lowering the foils in some kind of creative, artistic steampunk kind of way. A big rusty wheel, a stream whistle, some archaic command to relay to the larboard foilhands....aaaarrgh put ya backs innit ya landlubbers!! I have awards for extreme heavy transport mobilehone design and construction. I have NDA's with NZ top boat builders and naval architects about this catamaran concept. Which is now a working small scale. 40:1 radio controlled (I'm a Commercial pilot I have no interest in radio control toys.. But alas.. Give me a good x-plane or msfs SIM any day for IMC flights into unknown countries/fields with a nice glass cockpit) ( the small scale has about 10 servos, rotating mast, traveler. Flight control stabilisation on pitch[ centreboard and rudder foils] and yaw[rudder].. My brain hurts) . They all think my revolutionary stability ideas (undisclosed)are a good idea... Getting back to the original question?? Steering boxes, worm drives etc etc... Any takers??? Cheers

 

[WKTaylor]

I am only able to address peripheral issues of general mechanical reliability under demanding conditions.

IF we are unable to see a configuration, then... sorry.

WAG.
Seaplanes use a stepped-hull flotation... which quickly transitions from high-drag flotation to 'planing'[SP?] for a significant/quick drag reduction during takeoff... and [sorta] the opposite on landing.

Perhaps hulls designed for rapid transition to planing could facilitate hydrofoil actuation/engagement. This MIGHT require some aerodynamic assistance [mini wings and stabilizers] for lift/attitude/stability control... which could be useful in sustained hydrofoil 'flight'... especially over waves, crosswinds, turbulence, etc.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[Testpilot__]

I'm quite attracted to the flying boat step hull, and was considering a clip on fwd of the centreboard, for testing, but I seem to have enough sailplan and twin engine thrust to get to foil speed on a reach.
Also DSS and flight control
have become relatively mainstream in the market in one way or another from small moth, IMOCA, hydrofoil ferry, etc. I don't imagine getting stability under control with be an issue

 

[Testpilot__]

 

[rb1957]

I personally Hate the AC swinging foils. I think they look as clumsy as ... (insert whatever uncomplimentary word you choose).

Could you stow the idle foil against the non-foiling hull ? would look neater, and from your sketch, maybe not too much of a reach ?

I notice in your sketch

another day in paradise, or is paradise one day closer ?