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Personal Submarine Cruises SF Bay
LandSonar writes "Graham Hawkes, the guru of the submarine design business, tried out his new submersible sea plane yesterday in SF Bay. Called the 'Deep Flight Aviator'. Article and cool pictures. This craft doesn't use ballast like traditional subs. Flys more like a plane. 'It looks like something NASA might build or the Blue Angels might fly.'"
I didn't read the article but I saw this Submarine on TechTV last night. Pretty cool. Will cost approx $15,000. Now some people will have to make a choice between buying an over the surface boat or the sub...
The guy said they only used 2 engineers and lot of computer aided design to keep the costs low instead of hiring 50 engineers... It didn't seem to move very fast drifting nice and slow... It is supposed to go for as long as 8 hours on single battery charge and can go 1500 feet deep or something like that....
excuse spelling/gramattical mistakes, if any
The article states that, when the submersible drops beneath "stall" speed (approx 1.2 knots), a conventional ballast system kicks in to maintain dive depth - making it perhaps more versatile than conventional submersibles, as opposed to the limitations that you suggest.
> The article states that, when the submersible drops beneath "stall" speed (approx 1.2 knots), a conventional ballast system kicks in to maintain dive depth - making it perhaps more versatile than conventional submersibles, as opposed to the limitations that you suggest.
Note: the referenced article doesn't say this (yes, it's true), it's from a link to a description of the sub at the main site: http://www.deepflight.com/subs/dfa.htm .
Not Marianas, but you can certainly go explore SF Bay. PADI or NAUI should be able to connect you with the right people.
SCUBA is the best thing you'll ever do with your clothes on.
--
You sure got a purty mouth...
The problems at 39k feet are following:
#1) materials that can stand up to it. I'm sure that a piece of solid metal can, but can the cockpit? #2) If anything goes wrong...ANYTHING. you are dead. #3) Making sure your seals can stand the pressure (any that rupture - see 1 & 2)
However if the cockpit can sustain the pressures (since it is smaller than a full regular sub it should be able to take more pressure.) then it should be able to hit those depths no problem. Not only that, but at the proposed dive/accent speeds they might have to worry about the bends. at 400ft/min to go 37,000ft would only take 1.5h. All the "modern" subs/deep subs take much longer than that to hit those depths ('cept some military ones...but they don't go as deep [as far as we know])
This concept has actually been around for a while, however I give massive kudos to these guys for pulling it off not once, but twice. I watched the documentary on discovery about Deep Flight and that was cool. DF Aviator is definately a step in the right direction as it gets rid of the classic sub image.
As for increasing the speed for more than 6knots.. that is a simple equation.
Running time = battery power / draw of props (increases as revs go higher)
So either increase the battery capacity (for the same weight) and speed for the same running time. Or you will sacrifice run time.
Eg: To make it go ~12knots it would take roughly twice the battery power, reducing its effective time from 8h to 4h (I know there are more things..but that is the major factor).
Another technique is to increase the size of the props. But that takes more energy to get them spinning (for more thrust though).
RoundTop
This sub uses a conventional ballast system below
what it calls its "stall speed," but what you
say isn't necessarily so for other subs that use
a "no ballast" design. Think of the inverse of
moveable props like those used on VTOL aircraft.
You can use propellers pointing up to counter the
bouyancy.
One really good reason for not having ballast -
if you lose all electrical power, you float to
the surface. Think about it.
Baudtender
The pressure would pose a problem, but, contrary to what you might expect, the viscosity of water actually decreases with pressure, until around 150 MPa of pressure. After that, viscosity starts increasing with pressure.
That pressure corresponds to about 50,000 feet of seawater. Since (as far as I know) there is no trench this deep on Earth, we probably won't be having problems with viscosity anytime soon.
Water is definitely one of the most unique substances we have on this planet.
Just got to love those strong Van der Waals forces, that make water unique. (giving it all those neat pressure properties)
Since it is designed to cut through the water rather than force its way through (conventional sub) it should work.
There is no difference between how this submarine moves through the water and how a "conventional sub" would move through the water.
Making sure your seals can stand the pressure
Any rubber seals are just for the first few feet. After 30 feet the water pressure will be creating a metal to metal bond (or metal to acrylic or what ever) so the seals will not do anything. If you're refering to the metal to metal bond as a seal, then you kind of right, but any problems would have notice at around 30 feet. As you go deeper the bond will just get stronger.
Not only that, but at the proposed dive/accent speeds they might have to worry about the bends.
The bends only apply if you are exposed to outside pressure. This is a 1 ATM sub, you are always at the same pressure as you where on the surface.
Eg: To make it go ~12knots it would take roughly twice the battery power, reducing its effective time from 8h to 4h (I know there are more things..but that is the major factor). Another technique is to increase the size of the props. But that takes more energy to get them spinning (for more thrust though).
This isn't really true either, it would probably be more like a quarter of the endurance for twice the speed. But they might be other things limiting the speed such as drag, the sub isn't a very hydrodynamic shape and might have a low terminal velocity.
M0571y H@rml355.
No need to be rude...
Yes it does, the air is thinner up there.
it takes incomparably more energy to maintain a depth of 2000 feet compared to 1000 if you're not using buoyancy control.
A submarine displaces its own volume of water, and has a lift proportional to the difference between its weight and the weight of that volume of water at that depth. The density of the sea water hardly varies between the surface and the bottom (the pressure goes wayyyyy up, but water is largely incompressible), so the buoyancy is nearly the same.
Therefore the amount of energy needed is largely the same also; independent of altitude, for a fixed volume submarine, since you're only really fighting buoyancy to go down.
Also, in flight a wing uses reduced air pressure above the curved top of the wing surface (Bernoulli's Principle) for most of its lift. Does anyone know if this effect applies in water? Intuitively it seems like it would not.
Gee, I don't know, mister; ever heard of a propeller? That's a set of wings that rotate under water. Get a clue.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"I worked with these guys in high school up into this summer. H.O.T and Autodesk did some agreement with my high school where we got copies of Autodesk Inventor for free in exchange for drawing parts for the sub. It was a big PR thing for Autodesk. My classmate helped design the rudder system (Hawkes called it as fine as a "swiss watch") and me and a couple buddies modeled the mechanical flight system/joystick. I still have the Inventor files(no inventor though :( ) My friend who made the rudder eventually went to UCB and stayed on with the sub crew, designing and modelling parts. He got me a job with H.O.T's sister company which makes remote control gun platforms. :) Last I saw the sub it was about 80% complete. It's crazy they got it done...there was a joke around the gun company that it would never be finished. Hopefully I will go back and work for them this summer :-). Maybe I can get a ride...lol
I always thought that the bends occurred when ascending (coming back up to the surface), not descending (diving).
Being in a submersible that increased the air pressure to help ease the stress on the pressure hull therefore wouldn't cause a problem, so long as the air pressure was slowly brought back to 1 atmosphere on your way back up to the surface.
If memory serves, nearly all submersibles capable of deep submergence increase the air pressure at least a little to help counter the pressure of the water. In fact, if the air pressure was close enough to the water pressure, you could go outside and swim around (until you got hypothermia from the extremely cold water, anyway).
The only real problems with increasing the air pressure are oxygen concentration (as you increase the air pressure, you increase the amount of oxygen per cubic inch, thereby increasing the amount that you breathe in; too much oxygen will kill you) and making sure that the pressure is released slowly enough to prevent the bends (possibly resulting in the crew having to sit inside the sub after it has been brought back onboard while they wait for the pressure to drop to 1 atmosphere, depending on the sub's ascent rate).
IIRC, the bends only occur when you ascend too quickly (or the pressure in a pressurized sub drops too fast). The cure is to sit inside a pressure chamber, with the pressure racked up to equal what you would've felt at whatever depth you were at when you began your (too rapid) ascent, and then have the pressure slowly brought back to 1 atmosphere.
Ah, no. Air is compressible until approaching the speed of sound - which is why the speed of sound is what it is. That's also why there is a "shock wave" - since the air is not able to get out of its own way, and is also why it was originally believed that one couldn't travel faster than sound (though it was obvious that there were objects doing so, such as meteors, etc.). Approaching the speed of sound the induced drag rises rapidly - flying through that speed and continuing supersonic required gaining an understanding of how to reduce that drag (the "Coke bottle" shape of some aircraft designed during the 50's was one technique), and also gaining an understanding that the lift characteristics and center-of-lift point would shift - attention to design insured that this point did not deviate farther from the center-of-gravity than the flight control abilities of the time (i.e. - the pilot) could reasonably handle - think about the moment arm becoming greater as the difference between those two points increases. Also, it got much easier as we learned to build engines that could provide greater thrust.