XA 0.2 progress

We received the new tank Jon posted about in his last update, then made the brackets and went through the process of getting it installed in the XA0.2 frame.

36″ Tank fitup

Photo by Wayne Neumaier

Paragon did a nice job making the tank, and a thorough job in the packing to ship it to us. Once we proved that it was as expected and that this design will fit into the 0.2 frame, I drove it down to LA for cycle fatigue testing. It’s going to be pressurized and depressurized a bunch of times. The tank stretches very slightly each time it is pressurized, and we want to know if there’s a maximum number of cycles before it will develop a crack, break the weld, or fail in some way. We hope it passes, so we can use it as a spare, but if it fails that will give us good information on how many times a vehicle could be flown before the tanks would need to be replaced. There are other companies using or considering using this alloy of aluminum for their tanks, but no one has performed this test as far as we know.

The company doing this fatigue testing is Quality Precision Cleaning, right next to the Burbank airport. They do good work, have reasonable prices, and are conveniently just down the street from Norton Sales. We also use them for hydrotesting and LOX cleaning. SpaceX uses them for LOX cleaning as well, so we’re in good company. We had them re-test all of the surplus Atlas vernier tanks we had in the shop, and good thing, too—one failed quite spectacularly, splitting open along the weld. It was one that had been seriously abused, and not one we’d planned to use in a vehicle, but it was certainly good to break it in a controlled circumstance, rather than filled with a gas.

A note on LOX cleaning: oxidizers, such as liquid oxygen (LOX) and hydrogen peroxide, react strongly with anything organic, i.e. containing carbon. That’s why we use them; they react with the fuel and make the rocket work. But it also means that they will react with oil in rolled tubes, grease in valves, and even the tiny amount of oil in a fingerprint if you touch a fitting. So when we say “LOX cleaning”, it is a process of washing a part out with acids, bases, and alcohol, then drying it thoroughly (with heat and/or vacuum) to make absolutely sure that there are no organic contaminants anywhere that could come into contact with the LOX.

This must be done for all of the LOX plumbing, the purge plumbing (that blows into the LOX plumbing), the helium plumbing (that pressurizes the LOX), etc. Anywhere that something could end up in the LOX tank or plumbing has to be cleaned. We do some of the LOX cleaning here, for small parts, but have Quality do most of the larger stuff.

Vehicle comparison

Photo by Wayne Neumaier

Here you can see some of the difference between B and 0.2. XA0.2 will be a good bit taller with the engines and landing gear installed on the bottom, and the upper tank installed at the very top of the uprights. It’s actually tall enough that we won’t be able to stand it up in the shop except in a few places, and can’t get it out the door while upright. Obviously the tanks in B are much smaller, and as such B has about one third the maximum hover time.

XA 0.1 B progress

XA 0.1 B with plumbing

Photo by Ben Brockert

Here’s XA0.1B, with most of the plumbing in place. The LOX plumbing is removed and is being cleaned now. The purge plumbing will come off next; after it has been cleaned, we’ll be ready to pressurize all the plumbing for the first time and make sure there aren’t leaks.

You can see that I added casters since the last update, it makes moving it around the shop much easier. Though now it’s at just the right height for me to regularly hit my head on the triangles sticking out the sides. Luckily they turn out to be not necessary so I’m probably going to cut them off later this week. The casters are not landing gear; if we decide to do landing tests with B, it will have more appropriate landing gear added.

We installed the engine modules so that the plumbing could be run to them, but they’ll be taken off so that the rest of the modifications can be made. They get new hinge actuators, new valve position sensors, and a new electronics patch box. You can see all the cables dangling off, it’ll be my job to make them go somewhere.

Interns
I gave Wayne Neumaier, our current intern, a quick course in plumbing and he did most of the B plumbing himself. Well, except for one part of the LOX plumbing that I came up with, and Jon and Wayne decided was impossible; I had to make that. Wayne is also working on designing the engine modules for the 750lb engines.

Our other intern for the summer will be Melissa Schaffer, coming from the University of Cincinnati. She’s actually flying in today, her school is on the quarter system, so her summer break just started. I’ll be driving down to LA later today to pick up her and our tank. She’s in aerospace engineering with a minor in math, and has some good experience that will contribute to the Masten team.