Analysis of In-Flight Winds for Shuttle Mission STS 51-L

A Study of the Internal Boundary Layer Generated at the Alcantara Space Center

“…For ASC, it ranged from 1.6 to 2.6 x 107, based on the height of the cliff (H) and the wind velocity (V) at the top of the boundary layer (estimated between 200 and 300 m by Pires et al [40] and approximately 300 m by Reuter et al [41]). Figure 5 presents the dimensions in the wind tunnel of the scaled (1:1000) cliff and the RLP, represented by a wooden block of 10 x 10 x 50 mm 3 , installed at the centerline. To verify the influence of the geometry of the cliff, experiments were made with inclinations of 90º, 110º and 135º.…”

“…In addition to (i) the problems that lightening can cause (electrical surges can trigger loss of control and cause destruction of rockets); (ii) the formation of fog and ice on the vehicle due the temperature and humidity fields; (iii) turbulence that can impose unacceptable stresses on key structural elements and (iv) wind that can affect the electronic guidance system, the rockets can also be affected by turbulence when positioned at the ramp, prior to the launch [1]. All these aspects make the behavior of winds and atmospheric turbulence, especially in the superficial boundary layer, to be objects of great interest in Aerospace Meteorology, because their characteristics provide basic information for both Research & Development (R&D) of rockets and analysis of the ambient conditions in the case of failed launchings, as shown by (i) Uccellini et al [2] and Fichtl et al [3] concerning the explosion of the Space Shuttle Challenger in 1986, (ii) Winters et al [4] and Bellue et al [5] regarding Columbia's problem during its reentry flight and (iii) Kingwell et al [6] pertaining to weather factors affecting rocket operations. Wind data are also necessary for calculation of rockets' trajectories; for a typical Brazilian rocket launching, up to the height of 1000 m, 88% of the corrections in the trajectory are due to the wind, while above 5000 m this influence falls to 3% [7].…”