Thanks to all for the help.

I started this blog because I'd enjoyed reading about other projects from the engineering perspective. I'd hoped that others would enjoy reading this. What I did not expect is that I would receive help from my blog readers. The examples of this are numerous. I've had two different people run PET LN2 experiments and e-mail me their results. John Carmack of Armadillo has made numerous helpful comments. Just this week my son was working on my wound tank o-ring seal and went to visit "Real Seal" looking for Lox compatible seals.
My son discovered that Kevin at Real Seal is a reader of my blog. My son has been back once more to get a slightly different size and the people at "Real Seal" have been very helpful. I insisted that he pay them for the O-rings he picked up, but based on what McMaster Carr charges me for O-rings I suspect that the rings he got from Real Seal were sold to us at below market prices.

Using these new O-rings we put together another 3" wound tank. We finished it tonight and its holding water. I glued the end of the spectra down and I have to let that glue dry. We will pressure test the assembly on Saturday. I'll have pictures of the result as well as some pictures of our hydroforming fixture for making 8" aluminum end caps.

Some people may wonder why I'm spending all this effort on tanks. It's not very sexy and making hot flamey shock diamonds is much more showy, but the tank mass also appears in the rocket equation and if I can reduce the dry mass of my tanks by 50% its the same as adding 30 seconds of ISP to my rocket engine.