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Underwater Robot to Re-Cross Gulf Stream

Posted by Zonk on from the who-doesn't-like-a-good-robo-ray? dept.

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."

7 of 88 comments (clear)

  1. Converting buoyancy into forward motion by G4from128k · · Score: 5, Informative

    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).

    --
    Two wrongs don't make a right, but three lefts do.
    1. Re:Converting buoyancy into forward motion by OctaneZ · · Score: 2, Informative

      The bladder doesn't fill with water it is filled with oil which is stored in internal resevoirs inside the pressure case. This shift in volume while maintaining a constant mass is what allows us to change the bouancy.

  2. Spray Project Page by FreeHeel · · Score: 5, Informative
    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

    1. Re:Spray Project Page by Anonymous Coward · · Score: 1, Informative

      FYI, "Spray" is the name of the sloop in which Captain Joshua Slocum sailed solo around the world in the late 1800s. His book detailing the experience is available via Gutenberg and is, IMO, a very entertaining read.

  3. Re:price of energy by Bradee-oh! · · Score: 4, Informative

    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.

    --
    "This is Zombo Com, and welcome to you who have come to Zombo Com" - www.zombo.com
  4. Glider Info by OctaneZ · · Score: 3, Informative
    The glider was launched off Bermuda, and will make a roundtrip from Bermuda to Nantucket and then return to Bermuda to be retreived early this summer.
    Live Data is updated after each dive.

    there is also salinity data but fewer people are interested in that.
    This being slashdot I'll also directly link Some of the engineering paramters we track.
    1. Re:Glider Info by OctaneZ · · Score: 2, Informative

      For more information also see our instrument information page.