Scarlet Knight . . . The future of deep-water oceanography?

On December 9, officials from NOAA joined scientists from Rutgers University and other overseas institutions in a celebration highlighting the first-ever trans-Atlantic ocean crossing of an unmanned, underwater glider . . . 

The glider, launched off the coast of New Jersey last April, repeatedly dove to depths of 200 meters (656 feet) to collect data including temperature, salinity, and density. Scientists correlate these data with those from satellite imagery and altimetry, sea-floor and buoy-mounted sensors, and radar systems to get a more detailed view of a particular patch of ocean in near real time.

Source: NOAA's press release 

Further details about mission can be found at Rutgers University Scarlet Knight website.

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  • Jay ,

    yes that is the standard design ,been in use for more than 20 years and you are correct it is a displacement piston , i used the ballast pump designation as something nearly every one would understand , oh very early designs actuality had a pump and a fluid holding tank but the displacement piston  is far more efficient power and space/weight wise .  The current design is relatively unchanged from 20 years ago as far as the physical platform design only the instrument packages have changed radically . Oh and gliders  are very slow even with the high angle of attack dive /rise profile  about 1.6 KPH forward speed down or up and we are not talking about  speed over ground  we are talking dive/rise speed , a fair amount of surface area and wet weight displacement of less than a Kilo between rise or dive are the limiting factors to it`s speed , also the referenced model is a shallow water design at 50- 300 m max depth .

    There are units designed for far greater depths of up to 5000 m  these units "phone home " every so many cycles by sat link to transfer the collected data ,reprogramming on the fly  and final surfacing position  and recovery beacon . 


    What makes this a record  is it`s power lasting so long (better battery tech ) and distance with out servicing , they do not say anything about the data storage size but i would guess that it just had a final surfacing beacon for recovery not a phone home data system.

  • Might make a good project. Australian National Facility for Ocean Gliders  and Analysis of an Autonomous Underwater Glider Gives some good information.

  • The last design I saw didn't use a ballast pump so much as just expanded the internal volume with a bellowed piston, which changed displacement instead of weight.  Seemed simpler to me, but I'm not a naval engineer...

  • the extreme angles of attack are required because while they look and "fly" like an airplane  a) water is 66 times denser and b) the ballast system (and propulsion system one in the same ) literally only varies the weight by onces not pounds , it is taking in or expelling maybe a cup of water total each up or down cycle ,even a large one is moving maybe two quarts of water in or out of the ballast system which uses very little power ,most of the power is for instruments . That is why they have such range, a 3 m glider ballast pump is about the size of a coke can and uses only a few watts  per cycle .

    Info sampling gliders are very finely balanced between float or sink  and need velocity to keep course  

  • @Mike

    I figured it out right after I posted the question.  It is a pretty cool concept of propulsion. You can move forward both on the accent and decent phases if you use a symmetrical hydrofoil.

    I wonder, looking at the simulation video on their web site, the glider "flies" with pretty large angles of accent and descent.  Seems a bit excessive. 

  • video with song explains everything... https://www.youtube.com/watch?v=R53A7X21IR8&feature=player_embedded#!

  • @Mike, should have been more clear, I thought a previous Slocum glider had already crossed the Atlantic from Boston to Scotland sometime last year.  And now that my memory has warmed up and de-fogged, that was Rutgers too.  So same folks.  Guess it didn't quite make it last year?  

  • @Jay . . . The RU-27, aka Scarlet Knight, is a Slocum Electric glider.

    @Artem . . . carries enough battery power to drive a propeller for a few days at most, otherwise glider moves around by changing it's buoyancy (density) from surrounding ocean water . . . it changes its density by moving a small piston forward and back that increases and decreases its volume . . . a small change in volume (about a half cup of water) is all the glider needs to change its density . . . the wings give it a forward motion.

  • What is an underwater glider?  Does it just drift in the current without any propulsion system?

  • For a very informative interview of Oscar Schofield from Rutgers University about the autonomous underwater glider, visit the Robots Podcast: http://www.robotspodcast.com/podcast/2010/02/robots-auv-missions-html/

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