The prelaunch burn to verify system stability would only improve the T/W. For those saying it cannot be done, it is done already with every LRB we launch, including both the shuttle and the Atlas. We may be running it a few seconds longer, but it is already done.
Quote from: Downix on 07/15/2010 07:49 pmThe prelaunch burn to verify system stability would only improve the T/W. For those saying it cannot be done, it is done already with every LRB we launch, including both the shuttle and the Atlas. We may be running it a few seconds longer, but it is already done.not the same thing.
Quote from: Jim on 07/15/2010 07:51 pmQuote from: Downix on 07/15/2010 07:49 pmThe prelaunch burn to verify system stability would only improve the T/W. For those saying it cannot be done, it is done already with every LRB we launch, including both the shuttle and the Atlas. We may be running it a few seconds longer, but it is already done.not the same thing.Tell me, how is it different? You ignite before launch, correct? We take into account the burnoff from even the 6 seconds the shuttle is burning on the pad, we get the T/W into line.
Quote from: Downix on 07/15/2010 08:05 pmQuote from: Jim on 07/15/2010 07:51 pmQuote from: Downix on 07/15/2010 07:49 pmThe prelaunch burn to verify system stability would only improve the T/W. For those saying it cannot be done, it is done already with every LRB we launch, including both the shuttle and the Atlas. We may be running it a few seconds longer, but it is already done.not the same thing.Tell me, how is it different? You ignite before launch, correct? We take into account the burnoff from even the 6 seconds the shuttle is burning on the pad, we get the T/W into line. Sound suppression water volume? -Alex
Quote from: alexw on 07/15/2010 09:44 pmQuote from: Downix on 07/15/2010 08:05 pmQuote from: Jim on 07/15/2010 07:51 pmQuote from: Downix on 07/15/2010 07:49 pmThe prelaunch burn to verify system stability would only improve the T/W. For those saying it cannot be done, it is done already with every LRB we launch, including both the shuttle and the Atlas. We may be running it a few seconds longer, but it is already done.not the same thing.Tell me, how is it different? You ignite before launch, correct? We take into account the burnoff from even the 6 seconds the shuttle is burning on the pad, we get the T/W into line. Sound suppression water volume? -AlexSomething which can be adjusted for, I would imagine.
One of the more intriguing future possibilities would be to utilize the mid-air engine recovery that ULA (or was it LM?) proposed for the Atlas. An AJAX based on Phase II or Phase III boosters with mid-air engine recovery for the SSMEs and RD-180s could potentially achieve a pretty incredibly cost/kg, and also involve developments which would help the cost-effectiveness of the Atlas V.Moving to Phase II or Phase III could also potentially enable evolution to a crazy super-HLV if you increased the ET length, although of course that brings it back to the question of what sort of payloads one would put on it.Anybody know what mass figures would be like for Phase II/III-based CCBs? I imagine the thrust figures would be more-or-less a multiplier of the RD-180.
why not add some Atlas solids?
What are the open questions regarding the launcher that can begin to be addressed in this forum?
Can we calculate rough LOM figures based on past Atlas V performance?
What a day. Lets keep working on this concept, it wouldn't hurt to finish it out and have it out there in case SRMS go away
Quote from: neilh on 07/14/2010 07:02 amCan we calculate rough LOM figures based on past Atlas V performance?I think the best we could do is put some "bounds" on the LOM figures. RD-180 vehicles haven't flown that often!Atlas III -- with an RD-180 powering the first stage -- launched six times. Atlas V has launched 21 times. So that's 27 RD-180 flights without a first stage failure. Seen pessimistically, the record shows a stage powered by that engine fails at most one time in 28, or that the odds of success on the next flight requiring one engine are better than 96.43%. The odds of success on a flight requiring four independently successful engines are better than 86.46%. Using this same approach, it would require 71 successful single-engine RD-180 launches to generate better than 95% confidence of success for a four engine launch.
heck, who knows, 8.4m ET tanks may become a Commercially available off the shelf product for purchase by the makers of the Atlas rockets, once things settle down; and I JUST KNOW, JIM IS GOING TO TELL ME IT CAN'T BE DONE!! but neither was a NASA rocket suppose to be available for Commercial use, if memory serves; but I heard THAT IT WILL BE, mentioned at least once today;
If a chart like the one attached were a plot of an ascending vehicle's altitude and velocity, would there be a way "by observation" to determine max-Q?
Quote from: neilh on 07/14/2010 10:58 pmWhat are the open questions regarding the launcher that can begin to be addressed in this forum?I would also like to get a sense of where an AJAX-440 would hit max-Q. For that some sort of ascent simulation that includes even a simplistic atmospheric density model might be useful. It would also be good to get an estimate of when during ascent the vehicle could tolerate an early SSME shutdown. Could we say, for example, that the vehicle still reaches orbit if an SSME shuts down anytime after T+45 seconds?
now before anyone asks what would a 150+mt vehicle could carry