Monday, January 22, 2007

Crossbeams, leeboards, and outriggers galore!

After yesterday's long night, we stumbled back into the lab around noon. Chris was busy with studio work all day, so our crew consisted of Mike, Alan, and me. With crossbeams cut to length (4 10 foot pieces), we aimed to complete the attachment points on the outriggers and the main hulls. On the outrigger side of things, we needed to construct a sort of pylon to rise and meet the crossbeam, which, depending on our actual waterline, will probably be about 15 inches above the water. Since we are using foam outriggers, we decided to go with foam pylons. Using some of the stronger blue foam, we made 5 inch blocks that matched the contour of the outrigger on bottom. We left them flat on top ; they'll also get a 1.5 inch layer of foam rubber we salvaged from some shipping pallets. This squishy foam will take the shape of the crossbeam nicely, while ensuring that nothing slips around unintentionally. To complete the joint, we'll embed a wooden dowel or aluminum tube through the pylon, to serve as a lashing point. We added some wooden reinforcing disks (cut on the lathe) to spread the load throughout the foam. The whole assembly (minus the softer foam) was fiberglassed to the amas. The blended joint should be just as strong as the rest of the outrigger.

On the main hulls, we decided on a set of contoured laminated plywood blocks. The bottom of these pieces will be glued to the side and deck of the hull; the top will receive the streamlined crossbeam sections, with a thinner strip of the shock-absorbing foam in between. The blocks themselves were constructed out of laminated 1" thick spruce plywood, also part of the same shipping pallets. You never know what someone might throw away! We suspect the whole vibration-isolated pallet must have carried some sensitive scientific equipment, like a new mass-spec for the chemistry department. We finished all the rear brackets today, the rest will have to wait until the Design School shop opens back up on Monday afternoon.

We started work on the leeboards, cutting out the rough shapes. These will be made out of the same salvaged plywood, perhaps with fiberglass reinforcement if necessary. We spent a while discussing the possible hydrodynamic and structural costs and benefits of a pair of asymmetric leeboards versus a single symmetric leeboard (we are engineers, after all), and finally just went with the simplest option - a symmetric profile with a streamlined shape. They still look pretty rough, so pictures will have to wait until they get some more attention.

By the way, the weather in the area has been horrible this weekend. The 'wintry mix' of rain, sleet, snow, and more rain has been a real pain. Of course, we wouldn't have gotten nearly as much work done if our Aerial Robotics flight test wasn't cancelled, but that's neither here nor there. This has been a productive weekend, and we're knocking out tasks left and right.

Alan added a new feature to our sidebar, a map that displays the rough location of each of our individual blog visitors. We've gotten hits from all over the world!

Enough for now, leave us some comments if you get the chance.


1 comment:

DancesWithSandyBottom said...

Wow impressive work, as usual. You guys are amazing! A+

And... big thanks to NCSU for helping you develop all your outstanding engineering talents.