bobr@zeus.UUCP (Robert Reed) (02/17/86)
An AP wire story by Howard Benedict recounts a report presented by NASA spokesman Jim Mizell, which gives the following chronology: -- At 0.445 of a second after launch, a plume of black smoke burst from the side of the right-hand booster and was visible for about 12 seconds before disappearing. It was near a joint sealed by a pair of rubber O-rings intended to prevent hot gases from escaping from between two segments of the booster. -- At 58 seconds, smoke appeared on the side of the right-hand booster near a strut that attached it to the external liquid fuel tank. At 59.249 seconds, an intense plume of flame appeared in this area, and the chamber pressure in the booster rocket started to fall. Because of the pressure difference, the left-hand booster had more power and began tugging the shuttle slightly off course. -- At 62.484 seconds, the shuttle's computers tried to compensate for the difference by moving the right wing flap. Mizell said the flap was moved so abruptly that it created a "spike" in radio data, indicating that the flame must have broken through the right-hand booster in explosive fashion. -- At 63.924 seconds and at 65.524 seconds, the computers directed first the right-hand main engine nozzle and then the left-hand main engine nozzle to swivel to try to compensate for the off-course motion. Mizell said this subjected Challenger to an up-and-down motion "like a porpoise moving through water." -- At 66.174 seconds, bright spots and then a large glow appeared on the side of the right-hand booster. -- At 67.684 seconds, pressure dropped in the oxygen tank that fed the system of small jet thrusters that steer the shuttle, indicating that one or more of the jets were firing to try to keep Challenger on course. -- Between 72.01 and 72.281 seconds, Challenger was rocked severely when the two boosters began working against each other. One tried to move left and the other right and then suddenly, one pitched slightly up and the other down and the spacecraft moved sideways. Mizell said the crew probably felt this but had no time to report it. -- At 73.175 seconds, a puzzling cloud, perhaps from the liquid hydrogen fuel tank, appeared alongside the external tank. -- At 73.201 seconds, fire flashed between the shuttle and the external tank. -- At 73.226 seconds, the external tank exploded near the forward attachment strut. -- Robert Reed, CAE Systems Division, tektronix!teklds!bobr
bl@hplabsb.UUCP (Bruce T. Lowerre) (02/25/86)
> An AP wire story by Howard Benedict recounts a report presented by NASA > spokesman Jim Mizell, which gives the following chronology: > > ... > > -- At 62.484 seconds, the shuttle's computers tried to compensate for the > difference by moving the right wing flap. Mizell said the flap was moved so > abruptly that it created a "spike" in radio data, indicating that the flame > must have broken through the right-hand booster in explosive fashion. This doesn't sound right. 1) I'm not sure that the shuttle has flaps, it wouldn't need them. 2) Flaps operate together, not split fashion. However, if the shuttle has flaps and they are used for launch control, then this could be true. 3) Lowering (or raising) the right wing flap would add drag to the right side of the vehicle. This would aggravate the asymmetric thrust condition.
john@gcc-milo.ARPA (John Allred) (02/25/86)
In article <3312@hplabsb.UUCP> bl@hplabsb.UUCP (Bruce T. Lowerre) writes: >> An AP wire story by Howard Benedict recounts a report presented by NASA >> spokesman Jim Mizell, which gives the following chronology: >> >> ... >> >> -- At 62.484 seconds, the shuttle's computers tried to compensate for the >> difference by moving the right wing flap. Mizell said the flap was moved so >> abruptly that it created a "spike" in radio data, indicating that the flame >> must have broken through the right-hand booster in explosive fashion. > >This doesn't sound right. 1) I'm not sure that the shuttle has flaps, it ^^^^^ The proper term is "elevon", a combination of "elevator" (which controls pitch) and "aileron" (which controls roll). There is one elevon on each wing. The elevons can work in tandem or separately, depending on what type of correction is required. When the right elevon was commanded to move, Challenger was trying to keep its then current flight attitude by performing a roll. This suggests that the initial burn thru on the right SRB was to some extent off the SRB/external tank plane. -- John Allred General Computer Company uucp: seismo!harvard!gcc-milo!john