Gooding.WBST@XEROX.COM (10/14/86)
Consider the following scenario: A significant malfunction is detected during the early part of an STS mission following lift-off. The appropriate designated individual in mission control orders an abort. This order pops the tops of the SRB's off and away from the orbiter. Reverse thrust nozzles are now exposed and the SRB's top ends are ignited. The thrust of the already burning ends are effectively countered allowing the orbiter to detach before the SRB's buckle and submit to a destruct order along with the ET. The orbiter makes a best effort emergency landing based on speed, altitude, etc. Is this a viable method in which to minimize the risks of STS missions encountered from lift-off to SRB burnout? Steve <Gooding.WBST@Xerox.COM> Disclaimer disclaimer
dsmith@hplabsc.UUCP (David Smith) (10/16/86)
> This [abort] order pops the tops of the SRB's off and away from the > orbiter. Reverse thrust nozzles are now exposed and the SRB's top ends > are ignited. The thrust of the already burning ends are effectively > countered allowing the orbiter to detach before the SRB's buckle and > submit to a destruct order along with the ET. Based on what AW&ST said about the IUS/TDRSS failure (to the effect that continued chamber pressure is necessary to support combustion), maybe blowing the top off would extinguish the fire. Note that the SRB is hollow and burns from the inside out along its whole length. But if blowing the cap doesn't extinguish the motor, I doubt it would help. If the orbiter lets go, it will pivot around the rear attachment points and break up, as previously noted in this forum. If the SRBs are jettisoned, the orbiter and tank must fly through the plume. If nothing is cut loose, the front-end exhaust from the SRBs will impinge on the oxygen tank. David Smith
henry@utzoo.UUCP (Henry Spencer) (10/16/86)
> ... maybe > blowing the top off would extinguish the fire. Note that the SRB is > hollow and burns from the inside out along its whole length. But if > blowing the cap doesn't extinguish the motor, I doubt it would help... This may have been what NASA had in mind when they studied thrust-termination systems for the SRBs early in the shuttle development process. I don't have details. Their conclusion, according to the Rogers Commission report, was that it could be done. The problem is not shutting down the SRBs; the problem is that doing so in any straightforward way involves violent deceleration that the orbiter and external tank would not survive unless greatly strengthened. The strengthening cuts the payload to roughly zero. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,decvax,pyramid}!utzoo!henry
john@chinet.UUCP (John Mundt) (10/17/86)
One of the biggest problems early in flight is having enough of a velocity to make it back to the runway. If I understand you correctly, the reverse thrusters would slow things down before the orbiter detached. No profit in that. If the SRB's could be "pop-topped" the orbiter could then shut down the main engines and release from the ET while still maintaining as much velocity as possible.