Quote from: Downix on 11/05/2009 02:49 pmQuote from: sdsds on 11/05/2009 02:48 pmHuman-triggered AbortThere seems to be an assumption that for a launch vehicle to be "human rated" it must have an automated system that would detect trouble and trigger the abort/escape system.Why?For sake of discussion, assume there is no solid propellant; just liquid. Why isn't it enough to give the pilot an abort button, give the ground controller an abort button, and give range safety an abort button? Letś use Challenger as an example, how fast can you hit that button when breakup takes under a half second?The Challenger stack included solids, but let's look at it anyway. With a launch abort system triggered from the ground and a reasonably robust escape system pulling a reasonably robust capsule away from the stack, would the crew have been alive upon hitting the water?Evidence indicates that with Challenger, the crew cabin detached and was robust enough that some crew members were alive until impact.So there's no need for the crew to "hit the button" in under a half second. That's what the ground controller's button is for!
Quote from: sdsds on 11/05/2009 02:48 pmHuman-triggered AbortThere seems to be an assumption that for a launch vehicle to be "human rated" it must have an automated system that would detect trouble and trigger the abort/escape system.Why?For sake of discussion, assume there is no solid propellant; just liquid. Why isn't it enough to give the pilot an abort button, give the ground controller an abort button, and give range safety an abort button? Letś use Challenger as an example, how fast can you hit that button when breakup takes under a half second?
Human-triggered AbortThere seems to be an assumption that for a launch vehicle to be "human rated" it must have an automated system that would detect trouble and trigger the abort/escape system.Why?For sake of discussion, assume there is no solid propellant; just liquid. Why isn't it enough to give the pilot an abort button, give the ground controller an abort button, and give range safety an abort button?
Evidence indicates that with Challenger, the crew cabin detached and was robust enough that some crew members were alive until impact.So there's no need for the crew to "hit the button" in under a half second. That's what the ground controller's button is for!
Quote from: sdsds on 11/05/2009 03:00 pmEvidence indicates that with Challenger, the crew cabin detached and was robust enough that some crew members were alive until impact.So there's no need for the crew to "hit the button" in under a half second. That's what the ground controller's button is for!Incorrect,A. The ground does not active the LAS. The ground activates the range safety system which activates the LAS.B. The break up of the vehicle would have disable commands going from the range safety system to the LAS.Look up EDS and you will see why it has to be automated.
Well, not *completely* automated. The Saturn V EDS, to take an example, had only a few automatic triggers, mostly during first stage. Most subsequent aborts would have been crew initiated.
Quote from: Downix on 11/05/2009 01:36 pmWell, my concern with man-rating Delta or Atlas is simple, what is the history of either system with people? what was the history of the Shuttle before Young and Crippen climbed aboard? Lack of such "people" history does not by itself make a vehicle unsuitable, nor does having any such previous history necessarily make it suitable (as Ares I 5-segment SRB proponents would have you believe).
Well, my concern with man-rating Delta or Atlas is simple, what is the history of either system with people?
Quote from: Jorge on 11/05/2009 03:09 pmWell, not *completely* automated. The Saturn V EDS, to take an example, had only a few automatic triggers, mostly during first stage. Most subsequent aborts would have been crew initiated.Well, you don't need as strict requirements during subsequent stages, do you? Stuff like angle of attack limits when you're out of the atmosphere, etc.
1. Fund United Launch Alliance (ULA) to actually develop and flight-qualify the "strap-on" Emergency Detection System for Atlas V [...] tied to a NASA commitment to routinely purchase this system for use on all NASA Atlas V launches (e.g. unmanned spacecraft launches).
What benefit does an EDS provide to an unmanned mission? Is there any unmanned mission that would also carry an EDS-triggered escape system for the payload?
to the point that some of those contractors are telling their joint venture to cease and desist.
Also note that ATK has told the DoD that ending the Shuttle SRM line will affect DoD costs on ordnance and missiles. Ergo, the DoD is conflicted about SDLV or EELV.
It's happened so many times that it's an open secret around NASA and inside the Beltway. Objective evidence of the latest example should be available soon, but you'll have to know what you're looking for.
The problem would be if that sustaining fund is vaporized rather than transferred. This is an administration far more likely to add to NASA than to DoD.
Quote from: sdsds on 11/07/2009 05:14 pmWhat benefit does an EDS provide to an unmanned mission? Is there any unmanned mission that would also carry an EDS-triggered escape system for the payload?No benefit, the purpose is to test out the EDS in realistic flight conditions and see if the "emergency" detection part is working properly, i.e. not providing false positives etc. Then, once its flight proven it would be committed for crewed flights. One of the great things about testing upgrades in vehicles that also serve unmanned launches - risk reduction for human flights.
The instrumentation for EDS provides a little more insight into how the rocket is flying than the existing instrumentation. Added knowledge is useful to all customers if it improves reliability.NASA should be willing to shell out a few extra million for non-crew flights simply to build up additional insight into the EDS. This is one of the incredible benefits of sharing crew launch vehicles with everyone else. The added insight should lead to fewer false aborts.Commonality to should be advantageous to the rocket builder in the form of reduced costs and increased flexibility.
The Atlas EDS baseline includes a total of 76 parameters to be monitored, 37 on the booster and 39 on the Upper Stage. These are all existing parameters and are summarized below. In all cases, the data will be acquired from the redundant 1553 bus data and will use existing dual or triple redundant sensors.
Quote from: Ben the Space Brit on 08/12/2009 09:29 am@ agman25I'm no expert at the history. However, you have to look at the different backgrounds of the two times. OSP was one of the two designed major customers of the EELVs alongside DoD payloads. If the program had proceeded then, the EELVs would have been built as human-rated according to NASA's requirements and the pads would have been built to double as crewed launch sites. The DoD would have used the same machine and pads for their own launches and that would have been that. Now, we are in a situation where NASA is the 'johnny-come-lately' and the USAF is (perhaps, justifiably) worried that two perfectly good launchers may end up being ruined by NASA's bureaucratic fumbling or that human-rating work at LC-37 and LC-41 may delay their own launch schedules. Instead of being one of the two original major customers, NASA HSF is in the position of being a new customer who wants massive changes to the product that the original major customer isn't happy about.This was not the case. EELVs developed in the pre-OSP world and both were flying before OSP was initiated. DoD did cast a wary eye on the proceedings, but also recognized the value of enhanced reliability that HR mods would bring to the vehicle. Beyond structural and engine mods that would be built into all EELVs, HR would've been accomplished by so-called "mission-unique kits" which would be added to the standard vehicle during production. The kits would've involved sensors, some extra avionics boxes and the requisite harnesses.
@ agman25I'm no expert at the history. However, you have to look at the different backgrounds of the two times. OSP was one of the two designed major customers of the EELVs alongside DoD payloads. If the program had proceeded then, the EELVs would have been built as human-rated according to NASA's requirements and the pads would have been built to double as crewed launch sites. The DoD would have used the same machine and pads for their own launches and that would have been that. Now, we are in a situation where NASA is the 'johnny-come-lately' and the USAF is (perhaps, justifiably) worried that two perfectly good launchers may end up being ruined by NASA's bureaucratic fumbling or that human-rating work at LC-37 and LC-41 may delay their own launch schedules. Instead of being one of the two original major customers, NASA HSF is in the position of being a new customer who wants massive changes to the product that the original major customer isn't happy about.