
Ghost: Stealth Attack Hydrofoil Uses Supercavitation - Hoff
http://www.businessweek.com/articles/2014-08-21/juliet-marines-ghost-boat-will-be-hard-sell-to-u-dot-s-dot-navy
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sandworm101
Not stealth. Far to many flat 90/45* surfaces and corners. Nobody with any
understanding of radar was involved in the design of that thing.

Not supercavitating. Supercavitation is based on cavitation, not sucking down
air from the surface.
[http://en.wikipedia.org/wiki/Supercavitation](http://en.wikipedia.org/wiki/Supercavitation).
And the amount of energy needed to create a supercavitation void around those
hulls ... The Shkval is essentially an underwater rocket and it still uses
exhaust gases to top up the bubble in which it flies (see the little holes
near the nose)
[http://en.wikipedia.org/wiki/VA-111_Shkval](http://en.wikipedia.org/wiki/VA-111_Shkval).

Not a hydrofoil. No foils. It looks to be a SWATH hull (Small Waterplane Area
Twin Hull) another great Canadian invention.
[http://en.wikipedia.org/wiki/Small-waterplane-
area_twin_hull](http://en.wikipedia.org/wiki/Small-waterplane-area_twin_hull)

Who did this guy know at Businessweek to get this sales pitched turned into an
"article"?

~~~
hliyan
Won't an air envelope reduce friction as much as a vapor envelope?

RE: SWATH: their patent
[http://www.rexresearch.com/sancoff/sancoff.htm](http://www.rexresearch.com/sancoff/sancoff.htm)
discusses hydrofoils and SWATH as prior art [0182], [0183], but fails to
describe how their "buoyant tubular foils" (BTFs) [200] are different.

~~~
sandworm101
They're pontoons on movable outriggers. Novel, but useless. An air envelope
would certainly reduce friction but would basically kill buoyancy. Big metal
tubes don't float in air. So without any real foils/wings to generate lift,
even if a bubble could be formed, the pontoon would literally fall to the
bottom of the bubble.

Supercavitating hulls (ie the ShVal torpedo) suspend themselves within a
bubble via their noses. They are moving so fast that the nose, the only spot
where the torpedo touches the water, provides enough lift to keep the thing in
the bubble. But you need rocket-like accelerations to keep this going.

From their patent "whereby to provide propeller generated super-cavitated
water flowing from the propellers and thence along an outer surface of said
vehicle;" WTF? There is no such thing as super-cavitated water. Cavitation
presupposes a CAVITY, a void ... something other than water. Maybe water with
bubbles? Prop wash?

[http://www.google.com/patents/US20120097086](http://www.google.com/patents/US20120097086)

~~~
bradleyland
Another noteworthy design deviation (compared to run of the mill SWATH) of
this vessel is the dihedral angle of the pontoon supports. Based on the wake
behind the vessel, it appears that the pontoon supports might even be
providing some lift. This could provide a hydrofoil like lifting effect, but
the design of those supports wouldn't make a terribly efficient foil. The
aspect ratio is all wrong. Hydrofoils typically have a very short chord,
because water generates plenty of lift without a high aspect ratio.

This thing just sounds like a whole lot of smoke and mirrors. Hopefully the
guy can sell it to some Hollywood studio to use in Mission Impossible 10 so he
can recoup some of his investment.

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bazzargh
_Sancoff began contemplating ways to give back to his country. To him, that
meant shifting his focus from medical devices to weaponry._

That's a disappointing comment.

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idlewords
This thing looks like it could really turn the tide in our fight against
Cobra.

~~~
ch4s3
Yeah too bad these stealth designs work like ass against WWII era long wave
radar. Sure, you can't use long wave for targeting, but something this big
sitting so high out of the water seems easy to hit with a shoulder fired
rocket. It seems like these super high tech ships and aircraft exist mostly to
create jobs in various congressional districts. Then the get sold on the
mythology of a cold war nightmare scenario that never happened.

oh well. at least we're safe from COBRA.

~~~
lingben
"Hinges allow the struts to move up and down like wings. While parked, or
traveling through shallow waters, they can be extended to the side."

Maybe you missed this while scanning the article. This would allow the boat to
sit high or low on the water; reminds me of the citroen cx which had high
adjustable suspension.

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rdtsc
Another military device using supercavitation is the Soviet (now Russian)
supercavitating torpedo:

[https://en.wikipedia.org/wiki/VA-111_Shkval](https://en.wikipedia.org/wiki/VA-111_Shkval)

Max speed is 200 knots (230 mph) and it can go for almost 10 miles. That seems
almost unreal, an object that size, going at that speed under water.

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dm2
There are numerous problems with this ship but the main reason why it won’t be
used is that the US Navy already has a very similar ship that has been in
testing since 2006 and is all around better than the vehicle in the article.

[http://en.wikipedia.org/wiki/M80_Stiletto](http://en.wikipedia.org/wiki/M80_Stiletto)

50+ knots top speed, 4 x 1,650 hp engines

can carry a landing craft, 12 troops, and up to 20 tons of cargo

“A key feature of this vessel is that it can set up a network between a
special forces team by launching an unmanned aerial vehicle (UAV) that relays
information between the team and boat. The Stiletto can also carry
surveillance UAVs to provide reconnaissance for the SEAL team, and, using a
clustered supercomputer on board, will be able to send real-time images to the
team on shore.”

Cost between $6 million and $10 million each.

For extremely stealth missions SEALs would use a underwater vehicle deployed
from a C-130, another ship, or a submarine.
[http://en.wikipedia.org/wiki/SEAL_Delivery_Vehicle](http://en.wikipedia.org/wiki/SEAL_Delivery_Vehicle)

“The 88-foot (27 m) long vessel has a notable hull design, an M-shaped hull
that provides a stable yet fast platform for mounting electronic surveillance
equipment or weapons, or for conducting special operations. The hull design
does not require foils or lifting devices to achieve a smooth ride at high
speeds in rough conditions. Its shallow draft means the M80 Stiletto can
operate in littoral and riverineenvironments and potentially allows for beach
landings. The faceted design suggests that the vessel has a low radar
signature (i.e., stealth) in the frontal aspect and somewhat so from the
sides.”

[http://www.naval-technology.com/projects/m80-stiletto/](http://www.naval-
technology.com/projects/m80-stiletto/)

[http://www.wired.com/2008/09/stiletto-vs-
dru/](http://www.wired.com/2008/09/stiletto-vs-dru/)

[http://www.gizmag.com/stiletto-experimental-ship-with-
carbon...](http://www.gizmag.com/stiletto-experimental-ship-with-carbon-fiber-
m-hull-design-tops-50-knots-60mph/5151/)

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kghose
Also see ekranoplanes
[http://en.wikipedia.org/wiki/Ground_effect_vehicle](http://en.wikipedia.org/wiki/Ground_effect_vehicle)

(And hydrofoils, I was very excited by hydrofoils when I was a kid)

[http://en.wikipedia.org/wiki/Hydrofoil](http://en.wikipedia.org/wiki/Hydrofoil)

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thechut
Reminds me of the villains boat in Tomorrow Never Dies [1]

1:
[http://i.dailymail.co.uk/i/pix/2011/06/19/article-2005464-0C...](http://i.dailymail.co.uk/i/pix/2011/06/19/article-2005464-0CA0FEB500000578-484_634x261.jpg)

~~~
sandworm101
Which was based on the real Sea Shadow.
[http://en.wikipedia.org/wiki/Sea_Shadow_%28IX-529%29](http://en.wikipedia.org/wiki/Sea_Shadow_%28IX-529%29)

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rexignis
Nothing like this will ever compare with a submersible in terms of "stealth".
Who knows, maybe there already exists a supercavitating shallow draft sub for
the spooks to use.

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hliyan
Detailed schematics here:
[http://www.rexresearch.com/sancoff/sancoff.htm](http://www.rexresearch.com/sancoff/sancoff.htm)

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harywilke
Isn't cavitation a bad thing when trying to be quiet in the water?

