Is a supersonic boat possible?

Supersonic Car

Didn't happen.

The only car to go supersonic made four successful supersonic runs.

 

WIGs/Waveriders

A WIG/Waverider using supercavitating appendages to augment control and stability could be worth considering.

http://www.deepangel.com/html/the_squall.html

 

The major problem using supercavitating appendages on a surface craft is the penetration of the gas envelope made by the conection between the apendage and the craft on or near the surface. The whole idea of a supercavitating "torpedo" is that it envelops itself in a self made vapour "bubble". If vapour envelope is penetrated I think that it would probably collapse, or never develop, causing a "sticky" situation.

 

Supercavitation

http://www.ctechdefense.com/speed.html

2509 West 19th Street, Port Angeles, WA 98363
PHONE (360) 452-2275 * FAX (360) 452-2297 * info@ctech.esdcorp.com

Underwater Speed Limits
(Following is the full text submitted to Scientific American. The published version was shortened for editorial reasons.)

"There appear to be two conceptual ways of approaching supercavitation. The generally accepted one derives from propeller cavitation theory and holds that the water is essentially boiled by dropping its pressure via abrupt acceleration. This creates a source of gaseous water vapor which creates the cavitation bubble. It is generally assumed that the cavitation bubble is filled with this water vapor. Indeed, in low speed (say torpedoes) supercavitation applications the cavity size is usually enhanced with ventilation gases. This fits well with the understanding that gas creates the bubble in the first place and appears to work well within that context. It also fits comfortably in the general framework of marine engineering.

Last September, at an ONR sponsored Supercavitation Conference, Dr. Kirschner (of Anteon Corporation) and I were discussing the idea of a theoretical speed limit for supercavitating objects, assuming material strength issues could be overcome. As previously mentioned, conventional wisdom holds that the cavity is created by the water vapor and therefore, at some speed, the volumetric rate at which vapor can be generated will become insufficient to support the formation of a cavitation bubble which will clear the body. In other words, at some velocity the rate at which the water boils will become insufficient to fill the volume of the "hole" in the water created by the passage of the projectile and the cavity will collapse.

For whatever reason, I have a different mental picture of how the bubble is created, perhaps due to my background in hypersonics in graduate school. In that field discontinuities and rarified flows are encountered in the course of normal business. I do not know if anyone else shares this view but Dr. Kirschner and I have discussed it at some length. In any case, I believe the process is fundamentally one of momentum transfer. The cavitator, be it a disk or cone or whatever, imparts a significant radial velocity (relative to the axis of flight) to the water it comes in contact with. In effect the water is thrown violently to the side. It therefore has a high radial momentum that is resisted by the pressure of the water around it. This pressure serves to slow its radial velocity and will bring it to a stop over a finite time. The accepted definition of cavitation number is compatible with this idea. In the meantime, assuming a circularly symmetric cavitator, a round "hole" has been created in the water. What is in this hole, other than the projectile? I believe it is a vacuum, at least initially. Of course the water on the interior face of the bubble begins to boil, but it can only boil so fast, even in a hard vacuum. At slow velocities the rate of boiling can create a fairly decent partial pressure of water vapor in the cavity. In the limit case, as velocity increases, the pressure inside the cavity in the vicinity of the projectile will go to zero. Eventually the pressure acting on the water will reverse its radial velocity and cause the cavity to close. However, the projectile will be long gone by that point. If this approach is correct then, except for finding a material to withstand the steady state stagnation pressure, there may be no hydrodynamic upper limit to the velocity of a supercavitating body.

In any case, perhaps there is room for both viewpoints. In fact, they may very well be opposite sides of the same theoretical coin. I would certainly be interested to know what other people in the field thought of this approach. Perhaps it would provide an interesting topic of discussion within the article?"

 

These pics. show that is is possible to exceed the speed of sound underwater, The projectile is traveling at 1,549 m/s. I still have a problem understanding how a connection could be made to the "free surface" without creating a very unsteady mess.

 

Bubbles

For one thing, it's not like a balloon or soap bubble where if you pierce it it's going to pop.

 

Franklin: read the history of the supersonic car and the problems they had to deal with. The solution to the instability was a front spoiler.

 

What's the point???

 

The point is to do your homework before critizicing others.

 

Richard Noble

www.thrustssc.com

I was an acquaintance of Richard Noble's before he even set his 633 mph in 1983 and met him at the Bonneville salt flats in 1990 when he came to observe Art Arfons attempt on the land speed record. At that point, Noble was pursuing a boat for the transatlantic speed record and didn't even have firm plans for a supersonic car.

The key technology to making Thrust SSC work was an active suspension sytem that allowed the car's ground clearance and angle of attack to be changed on the fly.

 

the scientific american article above i seen before in another thread i replied on right?

great to be acquainted with Richard Noble and have tasted the salt Franklin!
and without taking any credit from his fantastice achievement i do like to mention, who was it? Breedlove, Arfons, i dont recall, anyway that supersonic speed was run before by another / others, just not official or both ways in time or something...
are there any plans for a supersonic boat? than whats a boat dito and totally insane i call it ahead of hearing, but hey, someone is gonna do it sooner or later i guess

 

Nobody went supersonic before Andy Green in Noble's Thrust SSC car.

 

Somewhere in Louisiana, RIGHT NOW, there are a couple of Cajuns with a 14' johnboat, and there mounting a surplus f-4 phantom engine on it. Oh, and there are a lot of empty beer cans around. Last one still standing gets to ride it. That's all I got to say about that, gotta go, mama just put a fresh bowl of possum stew out.

 

Interpretation...

Hello...

Here 'ya go...

But seriously - when my alien brothers were having a go at servicing my plugins - they mentioned something torpedo like - something like shark-skin scales - smallish blades on large diameter contra-rotating rings which ran along the length of the vehicle - something about operation within a non laminar layer...

Then I woke up with wet sheets and found this picture...

SH.

 

mixed medium

This discussion has made me laugh and smile more than once. Seriously though, a boat goes through air and water. While the definition of "boat" might be taxed, I'd be curious to see a vessle that can travel over the surface of the sea at supersonic speed. This inspiration is largely due to this discussion. Option 3 perhaps?

Kevin Barry