The image above is a model that Ken made using the developed panels designed by Stuart Bloomfield. This is basically how the new boat will be built. The first step is to create the flat panels which are carbon over Corecell closed cell foam core. Then we cut-out each panel shape and form the top and bottom hull halves by placing the panels into a wood jig then joining them together with carbon tape.
The very first step was to test our panel making procedure by running some stress tests on a sample panel. Rick Willoughby suggested two tests – a break test and a flatwise tensile test. He also made a spreadsheet for us to record and quantify the results. Following are the photos and results for each test:
I coated another sample panel with an additional coat of epoxy which would simulate a surface finish coating (like micro and paint) and re-tested it. This .3 oz layer of epoxy made it a whopping 60 pounds stronger in the break test and it took 200 lbs to break it!
The most important test is the flatwise tensile test which measures the bond between the laminate layers and the core. What we didn’t want to see, is the laminate layers separating from each other, or separating from the core.
To break the 1.25″ diameter core sample took almost every weight I had – a total of 276 lbs!
This test resulted in a high 96% of theoretical optimal strength and it broke half-way through the core material which is exactly what we wanted to see.
We had the panel drawings printed out at full-scale. These will be used to trace the panel shape onto the flat carbon panels, then they will be cut out and assembled in a wood jig that will hold the panels in position until they are joined together and bulkheads are inserted.
This is a photo of Ken looking down the pattern. The exact length on the print-out was about 20 mm short of what it is supposed to be, so we are going to ask the printers to re-print them.
Helen and I are off on a hiking trip to Peru to visit Machu Pichuu on Saturday. It’s an organized hiking trip from lodge to lodge as we make our way from Cusco to the legendary ancient civilization of Machu Pichuu. I am going to take the opportunity to fit in plenty of trail running at altitude in preparation for my 50 mile ultra marathon in June.
Garrie on April 2, 2009
Greg;
I, too, have been building some 3D shapes by creating unwrapped and flattened (in CAD) panels. I then insert measured lines in the files before sending the files of to be printed full size. I've been using a 12" line to calibrate the printer. When the copy service prints out the first drawing, it's simple to check that the scale is correct by actually measuring the printed 12" line length.
Here is the development of the panels from the original 3D shape.
http://i58.photobucket.com/albums/g277/cfbb/TiOregonbody.jpg
Here is one of the files I sent to the printer with the 12" calibration line
http://i58.photobucket.com/albums/g277/cfbb/sirspeedy1.jpg
Garrie L. Hill
Elrey on April 2, 2009
Why not avoid the pattern-and-transfer issue and have your panels cut to shape on a Multicam?
Liza on April 2, 2009
Enjoy Peru – what better way to clear the mind and nurture the senses for your boat journey ahead than a hike along the glorious Andes.
Anonymous on April 3, 2009
Greg,
when you use long fiber carbon reinforcement please check the safety: When it breaks the long fibers become sharp needles that can harm you a lot. A safety measure could be to combine the carbon fibers with other fiber materials.
Titus
Thomas van Schaik on April 3, 2009
Greg,
While being in aircraft maintenance for 8 years, I can say I have enough experience with the core material you are using to say that youre going to have problems with water ingression in the core.
Subject core material does not seem to absorb any water when placed into water for e.g. 24 hours. But when exposed to water in combination with temperature differences, water ingression is bound to happen.
I base my experience on the similar core material that is being used on the DC-10 outbd flaps trailing edge wedges.
When possible, try to seal every(!) opening of the core to the outside air/water. Also before painting use a high end sealer/primer to eliminate any pinholes, or possibility of moisture ingression.
As you know almost every laminate is porrous.
We have had flaps that had absorbed almost 20 lbs of water over a portion of 2 feet, by 1 foot, by 4 inches.
Hope this helps!
Thomas van Schaik
KLM Wide Body Structures Engineering