Historical Photo Of The Month - September 2004

Wind Tunnel Data Accumulation
Photograph Number 371-990C

In today's world of high-speed computers, it takes only seconds to collect test data at JPL. This is the result of continuous improvements in collecting data and the development of better technology to process it.

An example of an early improvement in gathering wind tunnel test data at JPL came in 1955, when a new high-speed data accumulation system was built for the two supersonic wind tunnels then in use. Until this time, members of the JPL Computing Section did data reduction and graphing by hand. During wind tunnel tests, the new system recorded data on punched paper tape. The data were input into an Electrodata digital computer, and then generated by a Flexowriter printer and a plotter. Engineers began to receive data more quickly than before, thereby increasing the pace of testing. The system also eliminated intermediate data handling before computation, and lowered the cost of data reduction.

Although the technology existed to have a direct connection between the test equipment and a computer, producing immediate test results, the method described above was used due to cost. Because a wind tunnel could use only 25 percent of a computer's time, and a dedicated computer was a substantial investment, the decision was made to use the paper tape system and a shared computer, which provided a half day turnaround time for the wind tunnel operators.

For more information about JPL wind tunnels, see the September 1997 and December 2001 Historical Photos of the Month or contact the JPL Archives. This photo is from Automatic Data-Accumulation System for Wind Tunnels, JPL External Publication 274, 1956, by J.J. Wedel, A. Huntington, and M.B. Bain.

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