Post by Chicago Astronomer - Astro Joe on Apr 3, 2006 10:36:50 GMT -6
Effects of a Saturn 5 launch pad explosion
Early in the Saturn development phase, NASA officials had carefully selected a launch site that was sparsely populated and where the actual launch pad could be isolated from other necessary facilities such as the Launch Control Center. They selected sites on the Atlantic coast of Merritt Island, surrounded by swampland and beaches. In 1961 and 1962 NASA planners decided the locations of physical structures for the two Saturn 5 launch pads, and designated the pads Launch Complexes 39A and 39B. Because of the pads’ isolation, after 1962 Saturn designers were less concerned about the damage that a launch pad explosion could do to the surrounding area than they were about the damage that an explosion could do to the astronauts who were trying to escape it.
In late 1964 or early 1965, the engineers at the Manned Spacecraft Center in Houston, Texas initiated the “Fireball Study” to evaluate the effects of the fireball produced during an on-pad explosion of either a Saturn 1B or a Saturn 5. In August 1965, Richard W. High and Robert F. Fletcher of the Flight Engineering Section and Mission Feasibility Branch, respectively, issued their report on the effects of a fireball produced by a Saturn 1B or Saturn 5 explosion.
Although the earlier explosion hazards study had indicated that the fireball posed no major threat to the Command Module itself, NASA engineers became concerned about the effect of radiated heat from a fireball on the parachute shroud lines of a descending Command Module. It would do the astronauts no good to escape the initial explosion and the fireball only to have their shroud lines burn up because of the heat of the fireball. Plummeting to the ground from a thousand meters was no better than being crushed in the initial blast wave.
Colliding with the tower would immediately rupture the fuel tanks causing fuel to flow out and contact the hot engine exhaust, leading to an explosion in fractions of a second. Tower collisions had been a major concern for earlier rocket programs, including the Saturn 1. Saturn program officials even placed cameras on the top of the Saturn 1 launch tower looking down to assist in manually determining if the rocket was sliding toward the tower.
In order to steer the giant rocket in flight, the Saturn 5’s huge F-1 engines could gimbal, or move, in several directions, pushed by actuators. In an engine hardover, a failed actuator would push the engine all the way to its maximum gimbal limit, rolling the rocket in the opposite direction and causing it to slide toward the tower. If this happened for one of the inboard engines before the Saturn had risen above the height of the tower, it could push the Saturn 5 toward the tower. It took 7.5 seconds for the Saturn to clear the tower.
Mowery concluded that: “no problem as to tower collision exists for combined disturbances if a malfunction does not occur.” In other words, simply wind or a misaligned vehicle, even in combination, could not cause a tower collision. In addition, neither an engine failure or an engine hardover for either of the inboard engines alone could cause a tower collision.
In order to steer the giant rocket in flight, the Saturn 5’s huge F-1 engines could gimbal, or move, in several directions, pushed by actuators. In an engine hardover, a failed actuator would push the engine all the way to its maximum gimbal limit, rolling the rocket in the opposite direction and causing it to slide toward the tower. If this happened for one of the inboard engines before the Saturn had risen above the height of the tower, it could push the Saturn 5 toward the tower. It took 7.5 seconds for the Saturn to clear the tower.
Mowery concluded that: “no problem as to tower collision exists for combined disturbances if a malfunction does not occur.” In other words, simply wind or a misaligned vehicle, even in combination, could not cause a tower collision. In addition, neither an engine failure or an engine hardover for either of the inboard engines alone could cause a tower collision.
Read the entire fascinating story here: www.thespacereview.com/article/591/1