Clark Lindsey posted some links on Hobbyspace to a recent presentation given by SpaceX at COMSTAC. The Briefing had some interesting pictures and information, and this one at least doesn’t appear to have any sort of statement saying it shouldn’t be distributed, so if they don’t mind, I’m going to post a few of the pictures and a couple brief thoughts.
There isn’t really all that much that’s new in the presentation, but I did notice that apparently my understanding of their tank design was a little bit off. I thought they were using a design that had the tank walls, with a couple of ring stiffeners, but no stringers. I was wrong. So, in a way this is just a 21 century Friction Stir Welded version of how an aircraft wing is designed.
It’s also interesting to note that they appear to have resolved their supply issue with Lithium Aluminum. That’s good. LiAl is interesting stuff–really good fracture toughness, with excellent strength-to-weight. And if you’re using FSW for the welds, you get around a lot of the weird processing issues.
But the coolest bit from the summary was their pictures of the Merlin 1C. Apparently the powerpoint file has some pretty sweet high-res pictures. Back in the summer of ’03, before I got involved with Masten Space Systems, I paid a visit to their rocket factory. Their VP of Business Development, Gwynne Shotwell was nice enough to give me a tour of the place, and I was interviewed by Chris Thompson (then VP of Operations and Manufacturing). During the interview, we got talking about pintle injectors, since I had a fascination with the design, and SpaceX was using it. Chris told me that he and Tom Mueller and a few others of the original SpaceX crew had done some ameteur pintle injector based rockets over the years. When I showed him my designs I had done as part of a special projects class at BYU, he smiled and said something along the lines of “my, that looks familiar”. I’m not trying to be rude or belittling in any way, but when I saw those pictures I thought the same thing–“my, that looks familiar.”
Those first two are pretty obvious, and quite gorgeously done. This last one I think is a tube-wall nozzle extension, possibly for the upper stage version of the Merlin-1C. But I could be wrong. It might also be part of the closeout for the milled-wall chamber. Either way, it is rather impressively done. Though having a swirl like that in the nozzle tends to create a torque on the stage, which will induce a roll unless counteracted by the turbopump exhaust or RCS thrusters. My curiousity is definitely piqued.
Overall, I’d say that these engines look very nice, and I hope they have as much luck and success with their regen cooled pintles as we have–it’s definitely the right way to go. The designs are a lot more complicated than our designs, but probably a lot higher performance and a lot lighter weight than ours too. Tom Mueller’s team has outdone themselves. Having a real cooling system on their engines I think compliments an already quite impressive design. Now if only we could talk them into getting a real landing system to go with that stage…