The static and dynamic aerodynamic characteristics of the Viking Entry Vehicle have been determined experimentally in free flight in air at a Mach number near 2. Preliminary results have also been obtained in C02 at M∞ = 11. The low speed tests in air confirmed a region of dynamic instability previously observed at the Arnold Engineering Development Center (AEDC). The instability was greatest at the smallest pitch amplitudes but decreased with increasing amplitude until a limit cycle was reached at about 8°. The tests in C02 indicated increased drag coefficients of 3 percent with respect to those in air. Errors in the drag coefficient of this magnitude would significantly affect the reconstruction of the Martian atmosphere during entry of the Viking spacecraft.
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