Hey all, Andy's email got me looking around a little bit. I didn't find much that was inspirational.
Along the lines of what we were discussing http://www.f-111.net/ejection.htm Look at the diagram under "Antenna Leads Severance Guillotines" The picture Andy found http://www.adboo.com/cmnr/Image138.jpg Looks nice and simple, but i don't understand the mechanism. Similar to our discussion http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19700032701_1970032701.pdf Note the use of a cartridge squib, and O-ring. I browsed the patent database a bit http://patft.uspto.gov/netahtml/PTO/search-adv.html I'm sure i missed something significant, but i did see a trend developing. Most everyone uses a hollow tube with two side-holes for passage of the line as the main cutter body. Most use a pyrotechnically actuated piston sharpened to a wedge shape at one end, which drives the line against an anvil thus shearing the line. A couple patents i found mention the difficulty of shearing fine threads in a slack line, and the tendency of the threads to bind between the cutter and the tube. The most insightful solution to this problem i found is to insert a plastic sleeve into the side-holes of the cutter body and pass the line through the plastic. Patent# 3,452,631 April 17, 1967. The other one i liked was 3,885,484 May 27, 1975. They use a thin disk forced into the hollow of the cutter body and propelled by a cylindrical piston, to do the cutting. The idea here is that the very close fit and spring tension of the disk doesn't allow for any threads to get into the gap between the disk and the body. (And, hey, they claimed it worked ;) I updated the wiki with the old design info psas.pdx.edu/ProjectLV2LineCutters At the bottom of this page are some thoughts about where to go with the new design. It might be simply adding a plastic confinement ring, similar to the '67 patent, to the old design would solve most of our problems. [EMAIL PROTECTED]: > http://mysite.wanadoo-members.co.uk/Stratokap/PyroLineCutter.html > > I also found a couple links to commercial line cutters aka "reefing line > cutters". > http://www.airlifttechnologies.com/mechanical.htm > http://www.airlifttechnologies.com/Dereefer.htm > > Here is a system that is used by skydivers that has an altitude computer. > We might be able to use a couple of their line cutters (found under the > products/accessories section.) I would hope that these have some measure of > reliability. :-) > http://www.cypres.cc/Sites/englisch/Frameset01_engl.htm > > Finally,here is an illustration of the Apollo line cutters with information > in the follow up link: > http://www.adboo.com/cmnr/Image138.jpg > http://www.adboo.com/cmnr/earthlanding.htm _______________________________________________ psas-airframe mailing list psas-airframe@lists.psas.pdx.edu http://lists.psas.pdx.edu/mailman/listinfo/psas-airframe
