Saturday, October 28, 2006, 06:29 PM
The two prime tasks for today's work session were rebuilding the rocket motor ignitor and continuing work on the main valve assembly.
The first rocket motor ignitor was a good engineering demonstration unit (see the 6/10/06 propulsion blog entry), but was not made from materials that could withstand the high pressure and temperature that the real ignitor will experience, therefore we needed to rebuild the first ignitor with better quality hardware.
The upstream components of the ignitor (regulator, solenoids, check valves, etc) will remain the same, but the actual combustion unit will be replaced with stainless steel components (a 3/4 to 1/4 NPT adapter and a 3/4 to 1/4 NPT bushing make up the ignitor housing). Here is an action shot of a hole being drilled into the 3/4x1/4 pipe adapter for one of the two spark plugs:
And here is a picture of the team learning how to thread the newly drilled hole to accept the threaded spark plug:
The team finished the ignitor by the end of the day and it is ready to be installed on the rocket motor injector.
The other team continued their work on the plumbing system and began integration of the computer system and the actuated valves. By the end of the day, the team was able to operate each of the valves on the fuel side of the plumbing system using the computer system. The next step is to install the liquid oxygen plumbing components and actuation system.
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Saturday, October 21, 2006, 08:23 PM
Today the team continued our work on the motor plumbing. In addition to running lines, though, the team started drilling and tapping holes for pressure sensors. We also installed a sliding valve table which will keep the main valves (and associated hardware) together but will also isolate these items from absorbing motor thrust - allowing the load cell to receive a more dedicated load. Admittedly, the main propellant lines will absorb some of the thrust load, but that is nearly unavoidable.
Here are a couple of work day action shots:
In other good news, the motor injector is making good progress. This week, Roger machined the LOX dome and added an associated depression to the injector body:
Also, Nathan welded the middle ring in place:
We are very grateful to Nathan for his time and donation of his welding talent. All of the injector welding will be performed by Nathan - the middle fuel ring was the first step. Thank you, Nathan!
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Saturday, October 14, 2006, 06:47 PM
Today and on the 12th the propulsion team worked on the plumbing system feeding the motor. Last week, we decided on the appropriate pipe diameters for the LOX low pressure helium and main LOX line. This hardware was purchased last week, and was installed today. Here are some highlights:
Nikolai and Ed successfully mounted the main fuel valve on its actuator:
Thomas and Michael finished up the low pressure helium plumbing:
Lastly, the team bent the main liquid oxygen and alcohol lines into the correct shape to feed the rocket motor. The lines were constrained by the requirement to navigate the arc between the bottom of the propellant tanks and the entrance to the test stand while minimizing pressure losses. A pipe spring was used with the conduit bender to ensure the pipe stayed round during the bending process:
Next week, the team will finish the main valve assembly, will install ports for the pressure sensors, and will learn about predicting failure modes and the correct steps to mitigate these risks.
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