Instrumentation during the Test

By Dan Cooper
August 4, 1999

This is where I sit during the test and watch the data from the instruments.

During this test I have been coming in early to perform some pre-operational tests to ensure that the system is working as advertised and to make certain that there are no discrepancies. By doing systems check before we start testing I can prevent the expense of "down-time" and expedite repairs before the running crew begins the run schedule or pressurizes the tunnel and starts to collect the data. So far on this test we have had very few problems.

While the test is actually proceeding I monitor and set pressures for different altitudes, and during model changes I am often called upon to help the model mechanics assemble different parts of the model.

Occasionally, we have to go in and change the configurations. We have had to do this on this test; in this case the researchers came to me and asked about the cavity pressures. Somehow the cavity pressures had been installed on the wrong ports for this test so that the transducer within the module couldn't read them.

I went out to the model and made sure I had followed all the procedures correctly. Then I found the tubes, which were supposed to be monitoring a pressure, and applied a vacuum gun to it, and waited to see if the port showed up as a negative pressure on the data system from a monitor in the control room. All of the instruments had been calibrated for this test at a neutral position which we call "zero to reference." We didn't see a negative pressure so we knew that the cavity pressure tubes were assigned to the wrong ports. I discussed this with the test manager and we agreed that the quickest solution was to hard-wire the tubes directly outside of the quick disconnect which saved several hours of repair time until a more convenient time for a proper repair would become available. The repair took 15 minutes, and then the cavity pressures were being read correctly.

You have to do the best repair you can in the time allowed. You have to be flexible. The test manager and the researchers are looking at the big picture of costs and tunnel availability, so they often make the decisions about how and when in-depth repairs can be made.

Sometimes I am the person who discovers a problem. For example, say a port pressure is not reading properly on the model. We try to keep the pressures within a certain range by monitoring how close our measurements are to the actual static pressures. This is done by making adjustments to the pressure system based on the angle of attack which can change the pressures on the model. When a problem port has been identified we can also make a quick correction to the system via data inputting so we won't always stop the data collection to correct the problem until the next model change.