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Engine test, fabrication, big tools

Engine Test

November 30, 2002 Meeting Notes


Engine Test


We added another 10 silver screens to the low-loss, all welded engine (for a total of 70), but it still wouldn’t catalyze worth a damn.  In fact, at a tiny throttle crack, you could see liquid peroxide just dropping out the engine nozzle.  We are pretty sure that the silver screens aren’t working correctly.  We noticed when we were doing the nitric acid wash that they weren’t coming out perfectly white like the last engine’s screens, almost certainly because we were reusing the same nitric acid that washed the previous screens, which had turned it a greenish color.  It may even have been poisoning the catalyst to a degree.


We really need to remember to always do catalyst activity tests before putting a new engine together.  We can test one of the remaining screens that haven’t been put in the engine yet on Tuesday.


I have ordered a supply of fresh nitric acid, which we will dilute to 10% concentration.  We should be able to just cap off the engine top, flip it over, and fill it through the nozzle until the entire pack is covered, then rinse it out in a few minutes.




Our first batch of honeycomb core composite panels arrived.  We wound up buying from www.teklam.com, but we also got price quotes from www.hexcel.com.   We are using 1” thick aluminum cores with fiberglass panels for the box fins on the new vehicle.  They weigh 0.69 pounds per square foot.  One neat feature of the panels is that the come with peel-ply on the fiberglass surfaces, so all you have to do is strip it off before bonding – no sanding required.


We found an improved method of cutting the 2’ diameter filament wound tubes.  After making all the measuring marks, we encircle it with a great big hose clamp (two, actually), and use that as a guide while using the cutoff wheel.


The new engine manifold is done, necessitating our first use of 1” NPT taps and hardware between the tank / master cutoff valve / distribution manifold.  We aren’t worrying too much about optimal plumbing losses, because this vehicle is going to have far more power than we really need.


Big Tools


Now that I am finally settled in at my new house, I am starting to bring in big tools for Armadillo.  My wife gets a nice big house, I get a nice big garage and office / workshop. :-)


I learned basic machining with a little Sherline lathe and mill, and have made a bunch of parts with them (Russ has a bigger lathe for the larger stuff), but I have been looking forward to getting proper sized tools for a long time.  I got a new Jet 14x30 lathe, and a used Sharnoa CNC milling machine.  I have some concerns about used equipment, but it was a pretty good deal for a machine with those capabilities.  While most of our expected mill work will be conventional X/Y/Z work, the machine also has a fourth axis rotary attachment, which makes it the perfect machine for automatic milling of channel wall regenerative nozzles when we get back to biprop work.


I still have to get them all set up and buy a bunch of tooling, but they should be making parts soon.


http://media.armadilloaerospace.com/2002_11_30/smallTools.jpg (chips don’t make it to the Ferrari)







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