Underwater Robot to Re-Cross Gulf Stream

karvind writes "PhysOrg is running story about a small autonomous underwater vehicle, or AUV, named Spray which was launched yesterday (March 25, 2005) about 12 miles southeast of Bermuda. The two-meter-(6-foot)-long orange glider with a four-foot wingspan will slowly make its way northwest, crossing the Gulf Stream and reaching the continental shelf on the other side before turning around and heading back to Bermuda, where it will be recovered in July. Spray made history last fall as the first AUV to cross the Gulf Stream, but this time it is making the trip from the other direction."

Comments

Re:Huh?

[Anonymous Coward]

http://spray.ucsd.edu/pic/spray.jpg

"'Spray' uses primary-lithium-battery power and a hydraulic pump to periodically change its volume to alternately glide upwards and downwards. This results in a see-saw path at descent/ascent angles of 18-25 degrees and forward speeds of 25-35 cm/s. Heading and ascent/descent rate are controlled without control surfaces by moving weight (battery packs) inside the hull to change roll and pitch, much as a hang glider is controlled."

Excerpt from TFA, http://spray.ucsd.edu/

Daydreaming...

[FrostedWheat]

I've often wondered how difficult it would be to build something like this that is solar powered (stays on the surface), has small simple engines, GPS and a satellite radio to call home every day or so. It would be slow but if nothing breaks it could in theory cross huge distances.

Would make a great competition! £20k for the first to cross the Atlantic from Newfoundland to Ireland!

It's just a cover-up.

[Rolling_Go]

So that those cokeheads can smuggle their stuff under the guise of "scientific testing".

Converting buoyancy into forward motion

[G4from128k]

It works just like a glider (wings and no propeller). By decreasing the buoyancy of the vehicle, it sinks and the downward drop of the vehicle is converted to forward motion by the wings (just like dropping a glider off a cliff). When the vehicle ascends, the same thing happens. The numbers in the article suggest a very modest glide slope of only 3.2:1. This means that each round trip to 3300 feet and back would provide 21120 feet (6.4 km) of forward travel. Do that 3 times a day, and you can make steady progress.

Changing buoyancy and gliding takes very little energy, much less than running a propeller, so the thing can run for a long time (about 300 days, according the the article).

Spray Project Page

[FreeHeel]

SIO IDG Spray Home

from the site:

What is SPRAY?

'Spray,' shown above, is an underwater glider developed under ONR support by Scripps and Woods Hole scientists (Sherman et al., 2001) to provide a small long-range autonomous platform for long-term ocean measurements. 'Spray' uses primary-lithium-battery power and a hydraulic pump to periodically change its volume to alternately glide upwards and downwards. This results in a see-saw path at descent/ascent angles of 18-25 degrees and forward speeds of 25-35 cm/s. Heading and ascent/descent rate are controlled without control surfaces by moving weight (battery packs) inside the hull to change roll and pitch, much as a hang glider is controlled. As shown below, at the surface Spray rolls 90o to raise one of its wings, each of which contains a combined GPS/Iridium antenna. Using the wings to house antennas eliminates the drag associated with separate antenna housings and allows redundant systems so that communication and navigation can continue even if one antenna is damaged, as happened when one Spray was run over by a surface vessel...

FreeHeel

Re:price of energy

[Bradee-oh!]

As a side matter, a google search on Li CSC batteries doesn't turn up much. What are they exactly?

Li/CSC seems to be an acronym for "Lithium Sulfuryl Chloride." Why they decided to make it look like Lithium/Computer Science, I dunno.

This is the best link I could find with a description of the different battery technologies that also mentions Li/CSC. It seems the main characteristics of the Li/CSC battery is that it's rechargable, carries a higher-than-average voltage, has a VERY high energy density, and is suitable for high-current applications. It seems the ideal match for the Spray-type application.