AI.CLIVE@MCC.ARPA (Clive Dawson) (01/31/86)
One aspect of the SRB self-destruct mechanism which has bothered me the most is the fact that a single action will destroy BOTH SRB's (and perhaps the external tank as well?). It is clear that recovery of the intact casings would have been invaluable in the NASA investigation. News reports tell us that one of the SRB's was headed on a dangerous course toward popluated areas and had to be destroyed. Fair enough. But why destroy the other one unless and until it was also proved necessary?? Thinking about this further reveals it may not be that simple. First of all, I can imagine scenarios in which both SRB's would need to be destroyed as quickly as possible, especially in the early phases of the launch. You would certainly want to have a mechanism for doing this as exists now. On the other hand, last Tuesday's events show that it would be very valuable to be able to destroy them individually as well. This would imply modifying the hardware/software such that each SRB responded to two destruct commands: a common one for both and an individual one. Perhaps a simpler scheme would be to simply have two different frequencies which could be used simultaneously or separately. Those of us discussing this were momentarily satsified until somebody asked, "Yes, but how do you tell which SRB is which??!" In this case, it was reasonably easy to answer that question when they emerged from the fireball, but this might not always be the case. Furthermore, it's not clear that the task would be any easier when watching them on a radar screen. (What does the Range Safety Officer use?) This difficulty can presumably be overcome by electronic equipment on each SRB that would tag its radar image in some fashion. I'm wondering if this is a case of "good hindsight" or if there are other considerations we didn't think of. Clive -------
space@ucbvax.UUCP (02/05/86)
I think you're right -- one destruct channel serves all 3 objects. However -- are YOU sure which booster was which? I had assumed that the one first seen sticking out the top of the fireball was the near-side (left) SRB, but who really knows? Your suggestion of a radar transponder (std eqpt on most civil aircraft) would certainly solve the problem. mike k
gbr@mb2c.UUCP (Jerry Ruhno) (02/05/86)
> One aspect of the SRB self-destruct mechanism which has bothered me the > most is the fact that a single action will destroy BOTH SRB's ........ I have read a lot of interesting on the SRBs which really surprised me. First of all if one SRB is destroyed then both are. I think they send a signal to each but if one receives a destruct signal then it sends a signal to the other one incase the other SRB didn't recieve the orginal. (I my be wrong but that's what I remember the reporter saying.) Another interesting fact is that in the SRB the fuel is burning the [Hit return to continu[Hit return to continue]
gbr@mb2c.UUCP (Jerry Ruhno) (02/05/86)
> One aspect of the SRB self-destruct mechanism which has bothered me the > most is the fact that a single action will destroy BOTH SRB's ........ I have read a lot of interesting on the SRBs which really surprised me. First of all if one SRB is destroyed then both are. I think they send a signal to each but if one receives a destruct signal then it sends a signal to the other one incase the other SRB didn't recieve the orginal. (I my be wrong but that's what I remember the reporter saying.) Another interesting fact is that in the SRB the fuel is burning the entire length of the rocket. When they send a destruct signal to the SRBs it DOES NOT BLOW UP THE WHOLE THING!! I never realized this. What is does is blow off the top of the rocket. Now with the fuel burning the entire length it ends up burning at both ends. This stops the forward motion of the rocket and it falls to the ocean. If it survives the fall and they can find it, NASA will be able to tell alot from it. As of Wed. Feb 5 NASA has said they think they found one of them but needs a closer look. Jerry Ruhno epsilon!mb2c!gbr
karn@petrus.UUCP (Phil R. Karn) (02/05/86)
It is depressing to see the sheer volume of misinformation coming from people who really ought to know better. Before you answer somebody's question with an air of authority, check your references! Then quote them. This applies almost as much to the news media as it does to this group. Two errors in particular come to mind: 1. Contrary to the New York Times, nitrogen tetroxide is NOT such an "exotic material that it isn't listed in the Merck Index." The writer may have been confused by the fact that what rocket engineers call "nitrogen tetroxide" is actually a equilibrium mixture of N2O4 and NO2, nitrogen dioxide. The former is colorless, the latter reddish-brown, and the proportions depend on temperature. Chemists are more likely to call it "nitrogen dioxide", which definitely *is* in the Merck Index. 2. The range safety systems on the SRBs do NOT "blow the ends off". A look in any of the many detailed press kits given out by NASA and Rockwell would reveal that the range safety system consists of a linear shaped charge running almost the entire length of the SRB inside a cable duct. Detonating this charge splits the case open lengthwise. Linear shaped charges are used in a number of places around the shuttle vehicle, not all of them for destruct systems. For example, most of the SRB nozzle is routinely cut off by a linear shaped charge before the booster hits the water in order to reduce the impact loads.
rck@ihuxx.UUCP (Kukuk) (02/06/86)
> > > One aspect of the SRB self-destruct mechanism which has bothered me the > > most is the fact that a single action will destroy BOTH SRB's ........ > > Another interesting fact is that in the SRB the fuel is burning the > entire length of the rocket. When they send a destruct signal to the > SRBs it DOES NOT BLOW UP THE WHOLE THING!! I never realized this. > What is does is blow off the top of the rocket. ... > > Jerry Ruhno > epsilon!mb2c!gbr NBC Nightly News on Tue., Feb 4, described the SRB destruct mechanism as being made up of a strip of RDX running down the outside length of each SRB. This placement is intended (so stated Bob Bazell) to split each SRB lengthwise. Who's right? Ron Kukuk
klr@hadron.UUCP (Kurt L. Reisler) (02/07/86)
In article <463@mb2c.UUCP> gbr@mb2c.UUCP (Jerry Ruhno) writes: > >> One aspect of the SRB self-destruct mechanism which has bothered me the >> most is the fact that a single action will destroy BOTH SRB's ........ > > Another interesting fact is that in the SRB the fuel is burning the > entire length of the rocket. When they send a destruct signal to the > SRBs it DOES NOT BLOW UP THE WHOLE THING!! I never realized this. > What is does is blow off the top of the rocket. Now with the fuel > burning the entire length it ends up burning at both ends. This > stops the forward motion of the rocket and it falls to the ocean. > If it survives the fall and they can find it, NASA will be able > to tell alot from it. As of Wed. Feb 5 NASA has said they think > they found one of them but needs a closer look. > As of late last night, NASA thinks that they may have actually located BOTH of the SRBs. One is in relatively shallow water, and the other is over 1000 feet down. I hope that they have infact located them both, and that they can be salvaged. It would ansewer the question of whether the right SRB did actually burn through, and why. The answer to that question might move us a little closer to a resumption of shuttle launches. Kurt Reisler ..!seismo!hadron!klr The Dream is, and must remain, alive!
lmc@cisden.UUCP (Lyle McElhaney) (02/08/86)
> When they send a destruct signal to the > SRBs it DOES NOT BLOW UP THE WHOLE THING!! I never realized this. > What is does is blow off the top of the rocket. Now with the fuel > burning the entire length it ends up burning at both ends. This > stops the forward motion of the rocket and it falls to the ocean. Nuts. ibid. Lyle McElhaney ...hao!cisden!lmc
tj@alliant.UUCP (Tom Jaskiewicz) (02/08/86)
In article <463@mb2c.UUCP> gbr@mb2c.UUCP (Jerry Ruhno) writes: > I have read a lot of interesting on the SRBs which really surprised me. > First of all if one SRB is destroyed then both are. I think they send a > signal to each but if one receives a destruct signal then it sends a > signal to the other one incase the other SRB didn't recieve the orginal. > (I my be wrong but that's what I remember the reporter saying.) Nope. They are both listening for the same destruct command on the same radio frequency. You can't selectively destroy just one of them. -- #################################################################### # uucp: decvax!linus!alliant!tj ## Bernese are mountains of love. # ####################################################################
zarifes@bnrmtv.UUCP (Kenneth Zarifes) (02/12/86)
> people who really ought to know better. Before you answer somebody's > question with an air of authority, check your references! Then quote > them. > > actually a equilibrium mixture of N2O4 and NO2, nitrogen dioxide. The former > is colorless, the latter reddish-brown, and the proportions depend on > temperature. Chemists are more likely to call it "nitrogen dioxide", which > definitely *is* in the Merck Index. Chemists are more likely to call NO2 "nitric oxide". Check your references. -- {hplabs,amdahl,3comvax}!bnrmtv!zarifes --Ken Zarifes
pritch@osu-eddie.UUCP (Norman Pritchett) (02/15/86)
In article <463@mb2c.UUCP> gbr@mb2c.UUCP (Jerry Ruhno) writes: > I have read a lot of interesting on the SRBs which really surprised me. > First of all if one SRB is destroyed then both are. If the range safety officer were given selective control over which to destroy, what happens if he gets them confused. Actually, does anyone know if the range safety people get direct visual contact of the shuttle or do they only get radar contact? -- Norm Pritchett, The Ohio State University BITNET: TS1703 at OHSTVMA Bellnet: (614) 422-0885 UUCP: cbosgd!osu-eddie!pritch CSNET: pritch@ohio-state ARPANET: NPRITCHETT%osu-20@ohio-state (or) pritch@ohio-state