Author Topic: AJAX Launcher  (Read 470892 times)

Offline Downix

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Re: AJAX Launcher
« Reply #20 on: 07/15/2010 07:49 PM »
Something to remember as well folk, this is an initial design work, useful for a first launcher.  The T/W of a 440 is workable, and is in line with other first-launch HLV's.  (Apollo 4 was a grand whopping T/W of 1.13 don't forget)

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.
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Offline Jim

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Re: AJAX Launcher
« Reply #21 on: 07/15/2010 07:51 PM »

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.

not the same thing.

Offline Downix

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Re: AJAX Launcher
« Reply #22 on: 07/15/2010 08:05 PM »

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.

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.
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Offline nooneofconsequence

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Re: AJAX Launcher
« Reply #23 on: 07/15/2010 08:23 PM »

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.

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.
The correct question to ask is "do we have a requirement to launch in less than N seconds, such that propellant losses / venting create issues".

When does vehicle flight verification / validation of systems become a mission risk / pad liability?

add:
This is moot anyways because the issue is one of professionalism - you don't design to a flaw (T/W at a boundary condition) that you remove/reduce at the pad (remember combustion isn't  precision). More of a mindset then anything else.
« Last Edit: 07/15/2010 08:28 PM by nooneofconsequence »
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Offline alexw

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Re: AJAX Launcher
« Reply #24 on: 07/15/2010 09:44 PM »
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.
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.
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Offline Downix

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Re: AJAX Launcher
« Reply #25 on: 07/15/2010 09:49 PM »
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.
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
Something which can be adjusted for, I would imagine.
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Online Robotbeat

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Re: AJAX Launcher
« Reply #26 on: 07/15/2010 09:54 PM »
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.
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
Something which can be adjusted for, I would imagine.
Build more water towers? There's a lot of water that gets dumped in a very short period of time.
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Offline sdsds

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Re: AJAX Launcher
« Reply #27 on: 07/15/2010 10:32 PM »
There's no value at this point in discussing short-loading or off-loading or pre-burning propellant.  The big value right now comes from knowing that this is a relatively easy design that doesn't involve SRBs that nonetheless puts 75 t into orbit.

So it should be sufficient to look at a cautious design and show that it reaches orbit with the claimed payload.  The cautious design would include in its mass budget a core that would carry the same propellant load that a Shuttle SLWT carries.  I suggest it is reasonable to assume that at MECO this core (including residual propellant) masses 70,000 kg.  Note that compares with an empty mass for the SLWT of 26,500 kg, so with 14,100 kg of SSME mass it leaves plenty of margin for structural strengthening, residual propellant, and a flight performance reserve.

With that mass budget for the core we can show that the vehicle would reach orbit even if the core held only 90% of the propellant in a SLWT.  Moreover when carrying that amount of propellant the vehicle has a T/W of 1.15 as soon as the RD-180s are at 100% and the SSMEs are at 109%.

There's no violation of physics here, and it gets 75 t to LEO, regardless of what experts in Utah (or elsewhere) may try to claim. 
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Offline martin hegedus

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Re: AJAX Launcher
« Reply #28 on: 07/15/2010 10:45 PM »
Sorry if this was addressed somewhere else or a naive question of mine.  But if the need is to have more T/W at takeoff for the 100% CCB+Full Core or more mass to orbit for the 100% CCB+Short Core, why not add some Atlas solids?

Offline Lobo

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Re: AJAX Launcher
« Reply #29 on: 07/15/2010 10:55 PM »

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.

yea, like this:

http://www.ulalaunch.com/site/docs/publications/PartialRocketReuseUsingMidAirRecovery20087874.pdf

Which I've advocated would be a -great- way to recover a commercial crew taxi for reusability of the capsule.  If you were launching a crew taxi capsule on an Atlas V and recovering the capsule Mid-Air, you'd already have the practice and ability to start recovering the engines if the flight rate was enough.  Although, if a SDLV was ever evolved into something like AJAX, you'd need a bunch of helicopters all in the air at once to get all those enignes!  Especially an 8 CCB variant!  Might get interesting.  :)

Offline sdsds

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Re: AJAX Launcher
« Reply #30 on: 07/15/2010 11:26 PM »
why not add some Atlas solids?

All of the other components look "easy" to certify for use with a crew, and thus it looks like the vehicle as a whole could be certified for that purpose.  In contrast Atlas solids look more difficult to certify.
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Offline FinalFrontier

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Re: AJAX Launcher
« Reply #31 on: 07/16/2010 01:36 AM »
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 ;)
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Offline sdsds

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Re: AJAX Launcher
« Reply #32 on: 07/16/2010 03:04 AM »
What are the open questions regarding the launcher that can begin to be addressed in this forum?

On the technical side, I'd like to see discussion of what it would take to build a core that: a) like Jupiter carries SSME thrust from below, and b) unlike Jupiter carries strap-on thrust from below.  Is this asking more of a monocoque "structural skin" LH2 tank than is reasonable?  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?

Then there are the political questions.  Has ULA ever in any context indicated any willingness to let NASA use a ULA booster in a non-EELV launch system?  Did Lockheed-Martin ever do so regarding Atlas, before the creation of ULA?  Has Energomash, PWR, or RD AMROSS ever indicated the RD-180 might be available for use outside the Atlas launch system?

Then there are the cost questions, especially when AJAX is compared to Jupiter.  For reasonable flight rates, how does a shift from Jupiter-130 to AJAX-440 change the total cost of operating the launch system?
« Last Edit: 07/16/2010 03:06 AM by sdsds »
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Offline sdsds

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Re: AJAX Launcher
« Reply #33 on: 07/16/2010 04:27 AM »
Can 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.
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Re: AJAX Launcher
« Reply #34 on: 07/16/2010 05:06 AM »
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?
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Offline cro-magnon gramps

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Re: AJAX Launcher
« Reply #35 on: 07/16/2010 07:11 AM »
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 ;)

First, listening to the Presser today, Nelson explicitly said that 70% of SRM was civilian and the rest DoD, and there was a lot of angst over at DoD about that civilian portion of the production line being shut down; so I don't think politically there is much chance that for the present the SRMS will be going anywhere;
Second, with regard to studying Liquid Rocket Booster and 8.4m ET combinations, I think this is very important, because while Direct can evolve to 150mt to orbit, I wonder if it can evolve beyond that, without a whole new rocket; the AJAX, looks like it could evolve a Direct SRB based launch vehicle beyond that limit; now before anyone asks what would a 150+mt vehicle could carry, I am thinking 30 years from now, and a study done now, like the NLS study, would be a back pocket item for some smart rocket scientist, when the need arose;

so bottom line, keep the excitement going and flesh out your design with contact with industry scientists, or who ever will help, and don't listen to anyone who says it isn't needed; 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;
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Offline neilh

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Re: AJAX Launcher
« Reply #36 on: 07/16/2010 07:18 AM »
Can 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.

It's worth noting that the human-rating publication for the Atlas & Delta calculates the LOM for the full Atlas V 401 (that's both the first and upper stage) as 1/250 (0.9960 success) at 50% confidence interval. It has a lengthy discussion about various ways to calculate LOM and LOC.

http://ulalaunch.com/site/docs/publications/HumanRatingAtlasVandDeltaIV.pdf
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Offline alexw

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Re: AJAX Launcher
« Reply #37 on: 07/16/2010 07:46 AM »
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;
    Shuttle was available for commercial use, in the 1980s. Turned out that NASA had to massively subsidize the launch slots, because of STS's overwhelming costs. We already know how that story ends.
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Offline alexw

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Re: AJAX Launcher
« Reply #38 on: 07/16/2010 08:00 AM »
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?
   With a little more data, you can find the answer you're looking for . Force of air resistance is:
       F_D = (1/2) * rho * v^2 * A * C_d
 
      So pressure is F_D / A, C_d is dimensionless, so you're just looking to maximize the quanity rho*v^2. The chart you've supplied is altitude vs. velocity, so now you need density vs. altitude; you can then eliminate altitude as an intermediate quantity.
   
      Start by looking up a table of a standard atmosphere model.

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Offline simcosmos

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Re: AJAX Launcher
« Reply #39 on: 07/16/2010 11:06 AM »
Quick Comments next:

Simulations and Virtual Telemetry


What 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?


Orbiter Space Flight Simulator and the tools (Vinka's multistage.dll) I'm using to implement a first order AJAX could be used for some trajectory related analysis as well mission designs. Virtual Telemetry can be exported into a .txt file which can then be imported into an Excel file, like the one that have shared on the DeltaIV Heavy CLV Brainstorm: EDIT: ooops, I mean, like the Excel with telemetry output that shared at the 'AresIB' brainstorm:
http://forum.nasaspaceflight.com/index.php?topic=13824.msg302387#msg302387


In addition Orbiter itself can draw some graphics (via default plugin) in real time as well another software - called Virtual Mission Control (vMC) - can be used to receive telemetry data from a running Orbiter session and draw graphics in real time too (vMC could even run on an external computer linking to a host computer to receive such virtual telemetry...).

All the above, together with a properly coded automatic ascent guidance, should be good enough to provide both quantitative and qualitative first order idea about things related with the ascent (T/W on several phases, maxQ, simulation of several ascent events / constraints / ground rules,  etc).

Of course that it would be nice to also have other more complex tools – such as POST -  not only to compare results with Orbiter Simulator but also to help building a more optimised automatic ascent guidance.


 
AJAX 440 Definition

As I have mentioned on past threads, there is a need to better define some launcher properties before moving on with improving eventual simulation quality...

There would be the need to focus and agree about CCB properties for AJAX application as well about the core properties, adapter mass and also, perhaps about the dimensions, shape and mass of a baseline payload fairing for simulation purposes... Perhaps better to think about such baseline payload fairing as being a long design and fully covering the maximum expected payload mass / envelope: if less fairing would be needed (because of later specific payload integrations then, at least, the simulation work would still provide a safer maximum load)... I would perhaps suggest to baseline an 8.4m diameter PLF for AJAX-440 baseline (with shape / barrel length to be yet decided).


For the CCB, summary from a post that wrote on the other related thread
(AtlasV boosters for AJAX – Definition of Properties (Masses, RD-180 Specs))

Source:
http://www.ulalaunch.com/site/docs/product_cards/guides/AtlasVUsersGuide2010.pdf
(http://www.ulalaunch.com/site/pages/Education_PublishedPapers.shtml)

   22997   kg : Inert Mass
284087.5 kg : Propellant Mass (LO2&RP-1)

3826961.674 N : SL 100% Thrust, ISP = 311 s
4151958.646 N : Vac 100% Thrust, ISP = 337 s

~0.25% of Prop. at RD-180 shutdown initiation (~710 kg)
(burnout mass would be ~23707 kg)
 
The above is only a summary, for extra data about why I would use these numbers please see:
http://forum.nasaspaceflight.com/index.php?topic=22122.msg616689#msg616689


Regarding the core, I have been using ~71.5t (average) if the baseline would be to aim for STS ET load (which have been assuming as 728t LH2/LO2 at SSME ignition start).
 

   
Payload Range: 70t / 100t up to 150t

now before anyone asks what would a 150+mt vehicle could carry

Quick comment about this: there are some recent talks about definition of HLV payload ranges; I would just like to note that, for example, the 150t payload number does not necessarily and strictly need to represent a monolithic payload with actually a mass of 150t... Such 150t can include, for example, the upper stage propellant for beyond LEO injection, in which case such propellant is also considered to be 'mission payload' and the 'real' payload (including adapter) could be ~50t or so... Depending of extra considerations and only as a very rough example, people could think about an upper stage containing a little more than 100t prop. at a given LEO insertion + about 50t payload (with adapter)  being injected beyond such first parking orbit (depending of extra considerations about mission design, payload, upper stage design, etc, such injection could be TLI, TMI... etc). EDIT: but better focus first, for the moment, on a better AJAX-440 definition.

António
« Last Edit: 07/16/2010 11:13 AM by simcosmos »
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