SEWEC prepares for testing in October

The last month has seen a flurry of activity. On June 19th we finished the 1/20th scale model and loaded it into the crate (Photo Patrick with crate) in California. Over the next 3 days it was driven non-stop across the USA to Maine whereupon Nick G, Nick W and Sean prepped it for operation (see photo Sean and Nick with wires) in the new wave tank at the University of Maine Advanced Structures and Composites Center in Orono. Sewec 1/20 was splashed on June 28th and floated to her marks! We then spent five days putting her through her paces - and everything worked - thanks to Byron and Nick G. We even ran the configuration to skip every second wave - reported as a simulation curiosity in an earlier team update - see the video https://youtu.be/hRo8dCcDndc so bravo to Sewec’s numerical modelling crew. And a big thank you to Anthony Viselli, Matt Fowler and Matt Cameron who got us up and running and got a ton of data for us at U of M.

Then back into the crate (see photo Tom with crate 2) minus PTO valve and orifice plates which we finally calibrated the following week at San Jose State University, in an upgraded rig. Back on the plane to Bangor the following Monday with the valve and orifices, get Sewec out of the crate and run a vacuum test at the U of M. The Advanced Structures and Composites Center routinely vacuum bag their composites and they kindly deployed their equipment and considerable expertise to evacuate and catch every last air leak on Sewec. The photo (Chris with vacuum) shows Chris Urquhart, vacuum maestro at U of M listening for leaks and photo (0.28 psia) shows the steady state value we ultimately reached of 0.28 psia. We need 1/20th of an atmosphere absolute (0.75 psia) in the Carderock test to account for scaling of the OWC air volume, so we should be ok. As far as we know, this will be the first time this technique has been used to increase scale model air elasticity so we really wanted to be sure we could pump 95% of the air out of Sewec, without leaks or structural collapse. Our fabricator Tom Johansing ran a stress analysis in May and said then “You’re good”. Thanks to Tom we are good to go.

Our team is the last to test at Carderock and this thought cheered me a lot as I loaded Sewec back in the crate Friday evening. Team Sewec “has a wrap” and is looking forward to an extended summer break.