Tag: Nilsen Strandskov (Page 2 of 11)

Hey All,

So we had quite a hectic weekend…

Saturday afternoon I received an emergency call from Tina and Dave that 29 was in trouble.  On the previous Thursday, the RUDICS server went down, preventing 29 along with gliders nation wide to be unable to call their respective doc servers.  This resulted in the gliders all calling in to Teledyne’s Doc Server as it was listed as a back up number.  Due to the overwhelming number of calls now flooding their lines, TWR’s doc server went down as well.  All along, we had little to no contact with 29.  Even worse was that this occurred just as we crossed the shelf, making the crossing even more stressful than normal.

She was successful in making it across the shelf untouched by fisherman, boats or the rapidly changing bathymetry, however, once she entered the shallow waters of the NJ Shelf, she was still commanded to make her top inflections 50m from the surface while diving to roughly 60m.  Now the pump that 29 is equipped with is of course a deep pump meant to be most effective when diving to a full 1000m.  So when 29 was then commanded to fly in 1% of the expected range for the pump, 29 chewed through the remaining battery available.

Waiting until Tuesday as planned for 29’s recovery was no longer an option especially with the weather becoming more severe as the week went on.  So we began preparing for an emergency recovery possibly that night.  After seeing what boats were available, we decided on Sea Tow’s Cape Hatteras which was the vessel used for deployment.  However, the earliest doc time available was 5pm, and with there being easily a 3 hr ride out to 29, that would leave us searching for her in the dark.

The next option was a 7am doc time which we agreed upon, and at 3:45 am, Austin and I departed from IMCS in the Glider Van to meet Dave in Atlantic City and try and recover our glider.  Upon arrival, we boarded the ship and left the marina at the Golden Nugget.

After about 3 hrs we made it the 60 miles off shore to where 29 patiently waited.  We then ran a ctd cast to compare to the data collected by 29 while we waited for the most recent gps location.

Although sunny, there was a storm brewing and throughout the day the waves and wind gradually picked up.  We then received a new gps point and started to close in on the location while 29 did one last dive to compare to our ctd cast.

When we got to the latest position, 29 sprung up right next to us, surfacing no more than 20 ft from the ship.  We then prepared to pull her on board.

Dave laid down on the deck while Austin took position with the dog catcher, and I took control of the recovery cart.

After some skilled maneuvering, we were able to slide 29 on to the cart and pull her up on board the ship and secure her in the cart.

As we headed back home, our friends back on shore spread the word that the “bear is in the igloo,” marking the success of the mission.

Click the link below to be redirected to the RuCool YouTube page and the recovery video for Ru 29!

RU29 Recovery Video

Hey all,

Over the past two and a half weeks, 29 has been put through a number of test missions in an attempt to see if she is suited for her long duration flight as she kicks off the Challenger Mission in the upcoming months.

First off, we set the limits for our testing area.  Where we crossed the shelf, we were dealt an area bound by two large warm eddies, one to our north and one to the south, the Gulf Stream to our east, and the New Jersey Shelf to our west.

The test path we chose was to run back and forth in our test bed parallel to the shelf.  However, before we even had a chance to start our test missions, we found our first anomaly.

As we approached the way point before our turn to the North West, 29 mysteriously turned to the south even though the current was pushing us directly at our way point.  After further investigation, we discovered that this was due to the gliders thought process.  What had happened was that Challenger got close enough to the way point that given the strength of the current, she thought that she was going to over shoot the way point while on her dive.  Because of this, 29 aimed itself in the opposite direction as to fight the current that was helping us, thus causing the turn to the south.

As for the tests, we started off with making sure she is capable of diving the full water column.  This is done by stepping down, or pushing the depth we dive to gradually down over the course of a number of segments:

Once we completed this, the next on our list was to do a spin test.  This test sets the fin to one side and holds it there for the entirety of the dive.

By keeping the fin stationary to one side, the glider is sent into a spin as it dives and climbs.  In theory, the glider should then go down and come back up in the same location, but due to currents, both surface and subsurface, we drift.  Then by comparing the drift to the gliders calculation of the currents, we can measure the accuracy of the gliders calculation for depth average currents.  After completing the test, we found the error to be a little over 20˚ which was deemed acceptable.

Next we looked into some of the engineering variables needed to optimize flight for the gliders.  This included adjustments made to the placement of the fin offset, dead band, and gain with various combinations of the three to see which settings would be optimal for our missions. A full listing of the tests and results can be found here.

Our final test was to see if we could successfully inflect at depth.  This was proposed a few times over the course of Silbo’s flight from Iceland to the Canaries due to strong surface currents that were harmful while at depth the currents were more favorable.  So if we were able to make our top inflections at depth, we could minimize our time spent in the poorer conditions.

It was a success!  29 did two tests, one test with two dives between 100m and 400m, and a second test with dives between 200m and 400m.

Now that we accomplished a majority of what we wanted to test (also our batteries have run pretty low), we have set the way point back towards Atlantic City to try and cross the shelf before the weekend in preparation for a recovery early next week.

As of the last surfacing, Ru 29 is mere hours from crossing the shelf into the depths. We were cautious over the past day as we were trying to time our crossing of the shelf as perfect as possible.  Now that summer has started, fishing levels shipping traffic have spiked as people enjoy the warm weather.  Knowing that if we continued straight towards the shelf, we would arrive mid afternoon when the traffic would be at its highest.  So we decided to enter station keep mode to bide our time for a few hours so we could put off making the crossing until late at night.

After 4 surfacings of following the station keep protocol, we moved the way point back out to the east as 29 now is making her way towards the shelf.

Looking at the bathymetry, it is really incredible.  By the last surfacing, we were flying in 150m of water, yet 5 km east, the ocean floor drops to 500m, in 10 km it is 1250m and the further we go the deeper it gets.

One observation we did make today was that there seems to be a bit of a lag on the inflection at depth.

Chip however shed light on this issue by bringing up the fact that 29 is a deep glider and the oil pump takes longer.  The problem may also adjust itself as we make our way into deep water which the glider is made to fly in.  Aside from that, She has been flying pretty well and has even minimized the time spent at the surface to between 7-9 minutes.

For the future planning, we made a list of points to take into account.  First off, in order to avoid ship traffic, we are doing our best to avoid fishing zones which also include keeping an eye on the Sea Surface Temperature as a front of 2 degrees could attract large amounts of fish and thus fisherman.  We have also increased the time between surfacings, and instead of making our top inflections close to the surface, we are making them at 20m.  We also have proposed to adjust the use of the altimeter to turn on at a deeper depth in order to conserve battery power.

Finally, the Gulf Stream is not less than 90 km from 29.  If we want to see this glider again, we must do everything we can to stay away from this massive current.  This year, the Gulf Stream has come up very close to the coast of NJ, and if we were to accidentally enter it, 29 would be in incredible danger.  With the battery packs on board, 29 only has roughly 20 days at sea giving us enough time to run two weeks to testing and get back close enough for recovery.  However if we get caught in the current, we will surely get launched out to sea.  Knowing this, we are doing our best to keep an eye on the currents to make sure we do not get anywhere close to the dangerous area.  To do so, we are using the RTOFS Ocean Basin  Forecast, real time satellite imagery, CODAR, and myocean from Antonio. But as for now, we have two way points waiting for 29 so she is set through the weekend

Hey All!

So a little while back, I had mentioned that Rutgers had received the first of what will be the fleet of 16 gliders meant for the Challenger Mission: Ru 29, Challenger 01.  This summer, while we were finishing up Silbo’s mission, a team consisting of Rutgers and U.S. Naval Academy students began preparing Ru 29 for its test mission.  Then, early yesterday morning, we departed from Rutgers and drove down to Atlantic City where we boarded the Sea Tow boat Cape Hatteras.

Once secured, we set off on a 50 mile, 2.5 hr trip to get out into deep enough water for Challenger to fly.

Once we were out far enough, the three students from USNA cast the Sea Bird ctd and ran the final checks in preparation for launch.

Then 29 was wheeled to the edge and it’s maiden voyage was under way!

Once in the water, the team moved into the cabin, where they ran a few tests to confirm everything was working correctly, before we sent 29 on its way.

Now, it is time to shift gears and focus on piloting.  We have a few things to consider over the next couple of weeks as we conduct 29’s test flight.  As of right now, we are flying in pretty shallow water (61 m).  Challenger, however is a stretch deep glider and so we need to get to waters over 1000m to run tests.  So we head to the shelf where the bathymetry drops from 150m to 2100m over 21 km.  However, between 29 and our our goal, there are quite a few obstacles: shipping lanes that can strike and sink us in the blink of an eye, fishing boats armed with nets that can capture us damaging the wings tail and ctd, and strong currents that can push us back towards shore.

To protect us from the shipping lanes and fishing traffic, we have a number of ais and shipping over lays for google earth that will steer us clear of the ships.  We also have a protocol which calls for making our inflections sub surface and making more yo’s between calling in to minimize time spent near the surface to keep away from the hulls of the ships. One the weekends, the fishing traffic on the shelf tends to pick up, and as today is the first day of summer, we can expect the area to be quite busy this weekend.  Judging by the currents, it looks like we will be roughly 4 days until we reach the shelf so we are discussing the possibility of waiting to cross until Monday, loosing us a few days of valuable testing, or risking the shipping and making a break for the shelf through the danger.

The other hazard at hand is the currents.  Looking at the previous 24 hrs compared to the most recent surfacing, it looks like we are seeing an inertial oscillation in which the direction of the currents do a complete 360˚ giving us a variation of stints of good and bad distance covered.  As we close in on the shelf, we need to keep an eye on the position of the canyons.  There, we see strong jets of water that could also slow us down, or potentially push us back towards shore.

Finally looking into the future, we need to understand what is happening in the deep water.  Once we get out, we only have a couple of weeks to run our tests.  We need to see how the currents are moving, that way we don’t get caught and pulled out too far away from shore.  This could potentially cut down the already limited time we have to run the tests we need. It will be crucial to keep an eye on all of these factors as we continue this test flight through the weekend.

Here is a link to the Ru Cool Flickr page for a complete set of the pictures I took along with a video of the deployment: http://www.flickr.com/photos/rutgers_cool/sets/72157630207739484/