Calibration shaker used for vibration testing (NASA Photo). The Calibration Group conducts acceptance testing by simulating conditions the equipment will encounter during flight. The Group also conducts vibration tests on instrumentation equipment to detect resonance frequencies incompatible with flight conditions, and frequencies that would disrupt the data collection process during flight.
The Calibration Group performs the following environmental tests:
The Calibration Group is able to simulate the following flight conditions with the use of its altitude and temperature chambers.
- Altitudes up to 150,000 ft; temperatures from б00 °F to 400 °F: 2 ft3 chamber
- Altitudes up to 100,000 ft; temperatures from б00 °F to 375 °F: 5 ft3 chamber
- Altitudes up to 100,000 ft.; temperatures from б00 °F to 400 °F: 6 ft3 chamber
The Calibration Group performs the following calibrations:
- Testing and calibrating accelerometers on computerized equipment that can duplicate G forces from less than one G to 100 G and display test results.
- Calibrating gyroscopes on a rate table, rated at 1000 deg/sec, an automated 14-in. square platform that simulates the pitch, roll, and yaw movements of an aircraft. The accuracy of the gyros, turning at rates as high as 10,000 rpm, is measured against simulated aircraft movement to validate accuracy.
- Using a special computer program to control each instrument's calibration process; computer test results provide a printed analysis of the results and archives the data.
- Monitoring equipment placed in the environmental chambers over data links that record test information on the lab's computerized analyzing system. Up to 20 channels of test data can be monitored by the computer system from the two small chambers, and up to 30 channels can be monitored from the large chamber. All three chambers have observation windows.
- Validating nearly all instrumentation packages and devices built by the Avionics Construction Shop, commercial vendors, and the Fabrication group.
- Performing destructive and nondestructive vibration testing of commercial and custom built instrumentation, data acquisition, and avionics equipment.
Calibration and Environmental Testing
To receive and transmit high-quality telemetered data, instrumentation used on NASA's aeronautical research platforms must withstand extreme environmental conditions such as vibration, temperature, and altitude. While providing reliable measurements of parameters being monitored most of the calibration work performed in aeronautical research is done on:
- Accelerometers: convert the G forces of gravitational loads into voltage outputs that are monitored during flight and for analysis.
- Pressure transducers: measure air or hydraulic (oil) pressure. They are used on wings, portions of the fuselage where airflow studies are being conducted, and hydraulic systems. Pressure generated by airflow or oil pressure is converted into an electrical output that can be monitored and recorded.
- Gyroscopes: generate precise data of aircraft acceleration, speed, pitch, roll, and yaw. This information is vital to a research project and is continually monitored and recorded during flight. The platform attitude and rate data are most often used as reference points when other test or research events occur.