by Pete Zell
July 6, 1998
The 1903 Wright Flyer test was assigned to me back when I was a test engineer several years ago. I've kept my interest in this test and I will be acting as Test Manager for this experiment. The role of the test manager is to make sure that the customer's requirements are met. The customer in this case is the Los Angeles Section of the AIAA. Their requirements are; the model be safely installed in the wind tunnel, all of their requirements for measurement are met, and that they get the data the way that they need it to satisfy their research objectives. This must all be done in a safe manner. No one should be injured, and the model should make it through the test in one piece. There needs to be efficiency in the entire process as well. There should not be a lot of lost time, energy, or money while doing this test. The test manager has responsibility for organizing the test planning and the conduct of the test.
I am responsible for the 1903 Wright Flyer being mounted properly, and safely, in the wind tunnel. The balance that we use must be able to meet the needs of AIAA's predicted loads. The sensors on the model must be hooked up properly and give the proper readings. I will ensure that the test is conducted safely and that the coordination with media is handled the way the customer desires. The Research Engineer will ensure that the data received is appropriate for the flight program that the AIAA wants.
The AIAA is very interested in the model forces and moments measured in the wind tunnel. That means we need to insure that the balance is operating correctly and providing good signals. It must not be overloaded, and it definitely must be correctly installed. We would also like to provide assurances to the AIAA that the signals measured by the balance are interpreted as the correct forces and moments. The Research Engineer has experience working with force and moment coefficients. He will work to increase our understanding of whatÕs happening with the model in the wind tunnel. This is critical to our success because we could spend time collecting data that's useless. If he spots something that is a problem, we can prevent that.
We really value the input of the research staff here, especially in the big wind tunnel, because our objectives tend to be research objectives. For example, "Does this technique for aerodynamics demonstrate this shape has a 1% aerodynamic improvement than the last shape?" Or, "Does this radical new wing configuration provide enough lift to achieve the goal?" This is more fundamental wind tunnel testing than production-oriented wind tunnel testing. The NFAC facility customers are making a big investment in their model because they have a fundamental problem. Their large investment is paid off by a large knowledge gain.
This test has been on the books for about 20 years. Originally it was going to take place in the 80 by 120 wind tunnel using our large external balance. When I received those sketches and plans it became obvious to me immediately that they wouldnÕt get the data quality the AIAA needed. The model weighs about 1,000 pounds, and the forces and moments it generates are very small. We came up with an alternative, which is to mount it on an internal balance at the end of the sting. The balance which is used for measuring the forces and moments generated by the model is very close to the model. This arrangement is much more sensitive to loads and we can get more accurate measurements.
We have been slowly gathering together the equipment and software which is necessary to mount the model in this special way. The AIAA has had to actually build special hardware to go with this new mounting approach. AIAA has been actively putting together a set of requirements for instrumentation, software and controls. We have received these and have been doing some preparation. Typically, on large-scale tests we do low-level preparation before the test, and the intensive preparation takes place in the last month before the test.
Scheduled before the 1903 Wright Flyer replica test is a test in the 80 by 120 for a helicopter, and there is a test for the Air Force in the 40 by 80 tunnel. The test of the Wright Flyer could take place in either the 40 by 80 or the 80 by 120, and the current plan is to run it in the 40 by 80. The reason we are pursuing that is the schedule right now shows the test occurring in the January to March timeframe and we could encounter rain or fog. In the 40 by 80 the air will not becoming directly from over the San Francisco Bay as it does in the 80 by 120. The air will be drier and a more comfortable for the test. The Wright Flyer is covered with untreated fabric. If the model is soaked by rain that could have a bad effect on the data. This is the kind of decision that the AIAA and the research team make prior to the test.