Researchers To Build Underwater Airplane

coondoggie writes to tell us that DARPA seems to still be having fun with their funding and continues to aim for the "far out." The latest program, a submersible airplane, seems to have been pulled directly from science fiction. Hopefully this voyage to the bottom of the sea is of the non-permanent variety. "According to DARPA: 'The difficulty with developing such a craft come from the diametrically opposed requirements that exist for an airplane and a submarine. While the primary goal for airplane designers is to try and minimize weight, a submarine must be extremely heavy in order to submerge underwater. In addition, the flow conditions and the systems designed to control a submarine and an airplane are radically different, due to the order of magnitude difference in the densities of air and water.'"

Crazy DARPA

Airplanes underwater??? This is crazy talk! Next they will wants subs that fly!

Re:Crazy DARPA

You're on the right track. Imagine a submersible aircraft carrier that launches flying submarines. Consider your mind blown.

Re:Crazy DARPA

Can I buy some pot from you?

maybe it would be easier

to build a flying submarine - I mean after all, if we made a brick fly (an old saying about the F-4 Phantom).

Steve Fosset

I don't have anything to say, but everybody else is posting stuff with "Steve Fosset" as the title.

Steve Fosset

I don't have anything to say either.

Roger Penrose

What? Oh sorry, wrong door.

TPM

Sounds like a few too many people at DARPA liked 'The Phantom Menace' a little too much.

This is Voyage to the Bottom of the Sea

http://en.wikipedia.org/wiki/Image:Flying_Sub.jpg [wikipedia.org] Someone's imagination is running wild. If DARPA is giving them money then it's time to turn them off.

Let's See.

Rocks sink, and Rocks Fly. Problem Solved!

I'm not sure

I'm not sure, but I believe those "underwater airplanes" already exist.. and are called "submarines".

start with mother nature

study up on flying fish [wikipedia.org] and flying squid [wikipedia.org]

then dabble in cormorants [wikipedia.org] and water beetles [everythingabout.net]

once again, mother nature was here first and has a lot to teach us about where to start

Water is 830 times more dense than air

Before they go too far with the designs, DARPA might want to check their figures for the densities of water and air. Last time I checked they differed by a lot more than "an order of magnitude" and I'd think this might be important.

Re:Water is 830 times more dense than air

My disgust for it grows geometrically every time I read it.

The scifi version would be supercavitating subs

Supercavitation [wikipedia.org] would allow submarines to move at supersonic (with reference to water) speeds while submerged, and dogfight underwater [space.com] like WWI aircraft did in the air. If they can come to a complete stop they'd be silent and invisible, just floating there, then fire up the engines and go back to moving faster than ship-based sonar would be able to detect them. There's already a supercavitating torpedo [wikipedia.org]. People who design targets -- I mean aircraft carriers and destroyers -- must be worrying about this.

Re:The scifi version would be supercavitating subs

Unfortunately, the *massive* power requirements of such operation mean that they require a rocket engine for propulsion -- and rockets have a rather substantial appetite for propellant. (BTW, the Shkval only goes at ~200 knots, not supersonic.) The shkval is largely rocket propellant, and even so only gets 7-13km range. There are almost certainly improvements possible, but I'd be surprised if you could build a sub that supercavitated for a long enough range to be useful as a sub and not just a missile / torpedo.

Requisite Futurama Quote

"We're taking over 150 atmospheres of pressure!"

"How many atmospheres can this ship take?"

"Well, it's a spaceship, so I'd say anywhere between 0 and 1."

What is up with the tags recently?

since when is "fuckofftags" a useful tag?

Re:What is up with the tags recently?

since when is "fuckofftags" a useful tag?

Not useful. Popular.

diametrically opposed is good!

They're saying how the requirements for submersibles and aircraft are diametrically opposed. That's good! If they were only kinda in opposite directions, that'd be a challenge. But calling on my vast electrical engineering knowledge (and what is mechanical engineering but electrical engineering with molecules instead of electrons?), I can tell you this is easy. What do you do if you discover that your current is diametrically opposed to what you want? That's right, you flip the terminals around, and bam your current is spot on!

So, using the same principle. In air you want the plane light and lift high because gravity means the natural tendency of the plane is to go downward and you want to go up. Underwater, gravity turns into buoyancy and your plane would naturally want to go up when you want it to go down. This sounds like our current problem -- we have a plane that flies perfectly in air, but in water goes the opposite direction of what we want. So what do we do? Yeah, we just flip it. Now the "lift" of the wings is pointed down. All you need then is an engine that works in air and water, and either a crew compartment that rotates to stay vertical, or sturdy straps and training for pilots to maneuver while upside-down. Done!

I just but the reversed-wing thing is actually used in some high speed submersible. Exercise on how to make it work in either direction above/below water left as an exercise for the DARPA grantee.

Re:Steve Fossett

Linky [slashdot.org]

Steve Fossett's Unfinished Project
Posted by kdawson on Sunday October 05, @02:36AM
from the ocean-flying dept.
Transportation Science Technology
MazzThePianoman writes "Steve Fossett left behind a secret vessel project called the Deep Flight Challenger. Fossett was funding the development of a winged submersible being designed by Hawkes Ocean Technologies in California. The intent was for the vehicle to be capable of travel to the very bottom of the ocean -- the Mariana Trench, more than 11,000 meters beneath the surface. 'It would have dramatically, dramatically opened the oceans for exploration. It would have been a game changer,' said Graham Hawkes, the designer. Testing had been completed at Department of Defense facilities. Field testing was only four weeks away when Fossett's untimely death, a year ago, put the project on hold." Hawkes Ocean Technologies owns the design but the vehicle itself is owned by Fossett's estate.

Re:Steve Fossett

No, this is an airplane that can also be a submarine (and surface vessel). Fossett was financing a sub that "flew" underwater.

Utterly Wrong

I love the self-assurance of the ignorant. Quite cute, really...

I work with ex-submariners. One of the reasons that they hated and feared a real reactor SCRAM was that the sub was essentially relying on its forward motion to maintain it's depth.

Yes, it was negatively buoyant, but the slight upward pitch of its planes enabled it to "fly" through the water. Supposedly, you get much more responsive control that way, rather than wallowing in the water while you wait for tanks to fill or empty. Very important, when you're trailing an aggressive Russian sub...

When the reactor shuts down and the screw stops turning, the damn thing will sink until the control team get the tanks set for neutral or positive buoyancy. Not a comfortable time as the boat heads down and the hull groans and creaks and everyone starts to wonder if there's enough high pressure air in reserve to blow the tanks.

Mainly OT, but by God and by golly, major navies do FLY their subs.

Re:Steve Fossett

This was Fossett's project I believe. They already have a design and partial prototype yes?

I think they've built a prototype, yes. Unfortunately, the test of the prototype of Fossett's follow-on project, an airplane that can fly underground, ended in disaster.

Too soon?

Re:WTF? Why am I paying for this?

You gotta keep scientists off the streets and out of trouble somehow.