HYSWAS anyone?

Thanks Jeff and Brendan.

I was thinking Jehardiman may have worked on this project.

Seems like it'd be right up your alley John.

-Tom

 

I believe that this was built by a company in Hawaii, NAVATEK, that does a lot of work with the ONR. They have built a number of vessels intended for rough water operation which incorporate various ways of producing low waterplane area hull forms. Many of them are SWATH, which maintain stability by having twin hulls and others similar to this which incorporate submarine type single hulls to keep wetted surface down. Obviously, the trick is keeping it uprght when the topside part is out of the water. So it is similar to a hydrofoil vessel with two modes, flying with dynamic control or floating where the hull provides the stability. The large center hull provides a significant portion of the "lift" and thus the foils are smaller than a more standard hydrofoil.

 

Not me, but perhaps someone else. I only touched on these things. See the following thread.

http://www.boatdesign.net/forums/boat-design/torpedo-hull-25491.html

 

Thanks John.

Somehow I had missed that thread.

Any idea how/if I could access any of the test data?

-Tom

 

looks more like a phallic symbol than a boat, are you sure is real?

 

Watch the video.

 

I have posted a short report in this forum on estimating SWATH resistance.
Similar techniques could be used to get a rough estimate of the resistance of HYSWAS.

 

Basically it's an airplane flying in the water, with some stuff mounted above.
Or a submarine with no ballast tanks.

The main complication will be due to water surface waves deforming the flow around the fuselage and foils but, apart that, the principles of aircraft stability and control are imo valid in this case. I think you should get a book about RC airplane design, to learn working with laminar-flow aerodynamics (which is hydrodynamics in this case).

 

Thank you gentlemen. ( Being a little presumptuous there. Correct me if I'm wrong )

It really is a lot like an airplane (especially in appearance! ).

It's simply flying through X800+ thicker "air" and at a constant alltitude.

I dabbled through out my engineering diploma schooling with aeronautical engineering.

In retrospect, I really should have taken that instead, but I digress.

The challenge I face is getting "lift off" with such little power.

To that end, I'm considering fixed angle of attack (AOA) wings that would assist in raising the hull out of the water and then rise up themselves reducing unneeded drag.

It's called "laddering" and is quite effective.

The other thing that is easy to forget is how unusual the competition rules are regarding loading, etc.

-Tom

 

It is like a cross between an airplane and a blimp. The torpedo part is intended to provide a significant portion of the lift so that the dynamic lift required to fly the hull is much less. I haven't seen data for this specific vessel but they have published many papers about some of their prototypes, trials, etc.

Look at http://www.navatekltd.com/ for some other very interesting design ideas. I don't think that any of these has had any great success. It seems to me that the surface peircing parts create as much drag as the gains in wavemaking?

 

Interesting site John, thanks.

Similar but not a lot of buoyancy coming from my pod as this would contribute too much instability and diameter.

With a goal of three diameters depth below the surface and a maximum draft of 20 cm I am limited.

-Tom

 

Your conceptual description is pretty accurate; your attribution not at all. The vessel was completed as a project for USN (one of the last 'hydrofoil prototype' projects undertaken by the legendary NSWCCD engineer J. Meyer and his group) by Maritime Applied Physics Corp..located at that time in Anne Arundel Country MD. The craft was built there and tested from there.

The principal engineer for the flight controls had worked for me and with me prior joining MAPC and taking on the HYWAS project. So while I was not directly involved in the project, I certainly understood all the technical nuances (25 years plus of building flight control systems for such odd vessels) and got the 'grand tour' of the craft as well. It performed very well.

 

That the 'challenge' you refer to is negligent with the HYSWAS concept is one of the primary factors that lead to its 'invention'; the pronounced take-off drag hump that characterizes a completely, or nearly completely, foil-supported vessel is quite reduced with the HYWAS, resulting a drag-speed curve that is fairly 'smooth' by comparison.

 

Sorry BMcF, it looked like many of their other designs, so I thought it likely that it was one not shown. Thanks for the correction.

 

oh heck..no apology was in order there. I apologize if you thought I was looking for one.

And having personally assisted Navatek in the design and development of more than one of their 'odd' foil-assisted concept vessels, I do know why you could have assumed that they had something to do with HYSWAS.