Author Topic: AJAX Launcher  (Read 475404 times)

Offline Lobo

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Re: AJAX Launcher
« Reply #1240 on: 07/18/2013 05:38 PM »
Downix,

You said AJAX could use an ACES-71 upper stage?

So my question is, would AJAX have done basically the same ascent profile as SLS Block 1?  With both cores taking the upper stage almost to LEO?
The DUUS they are talking about for Block 1B SLS only has four RL-10 engines on it, the same as ACES could mount.  Could SLS Block 1 mount a stretched ACES stage as it's DUUS, rather than a new purpose built stage with an 8.4m LH2 tank and 5, 5.5, or 6.3m LOX tank?  NASA would get their DUUS and ULA would get their common EELV upper stage.

I believe NASA is now looking at ACES as their new 5m CPS for their non-DUUS concepts.  Could they merge the concepts and have an ACES DUUS?

SLS will be a fair bit longer than the AJAX core would be, so maybe that would create a stack height issue that AJAX would not have had?

Offline Downix

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Re: AJAX Launcher
« Reply #1241 on: 07/19/2013 02:45 AM »
Ok, combining these two to answer.
What about a cluster of J2X engines?  Only suggesting that becuase J2X will be developed anyway, but RS-25E hasn't yet.  And AJAX is an alternative to SLS, so without SLS, there's not necessarily a need for RS-25E.  Especially with the much later booster staging of AJAX compared to SLS.  J2X has pretty good performance in vacuum...448s vs. 450s for RS-25.  Four of them would be about 350klbs less than three RS-25's, but should be pleanty of thrust by the time the Atlas cores separate at 250 seconds into flight.

What would be the likely per unit cost of J2X vs. RS-25E?  I'm guessing less because it's smaller and not staged combustion?
The J-2X is bigger, not smaller, than the SSME. It is also likely to wind up more expensive than the SSME at the same production levels. In addition, you would need 6 of them to replace 3 RS-25's, which you'd lack the space for under the tank. NASA actually did study this option on the RAC studies.
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Interestingly, the RD-0120 would be a GREAT engine for AJAX, or SLS, or Direct, or any expendable sustainer-core-to-orbit LV.  455s ISP at vacuum.  And apparently much more simple/cheap than RS-25, even though it's staged combustion.
Maybe the RS-25E will be similar to the RD-0120 in those ways?
That is the idea.
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But wouldn't require a new development program.  Although as it's out of production, it'd probably need new tooling to make.   

Guess it might make for a much "too Russian" LV though...
long out of production, it would take more time to set up than to finish the RS-25E program begun in 2002.
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Downix,

You said AJAX could use an ACES-71 upper stage?

So my question is, would AJAX have done basically the same ascent profile as SLS Block 1?  With both cores taking the upper stage almost to LEO?
Similar, but not identical. Lighter core gives AJAX a higher curve, more eccentric parking orbit.
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The DUUS they are talking about for Block 1B SLS only has four RL-10 engines on it, the same as ACES could mount.  Could SLS Block 1 mount a stretched ACES stage as it's DUUS, rather than a new purpose built stage with an 8.4m LH2 tank and 5, 5.5, or 6.3m LOX tank?  NASA would get their DUUS and ULA would get their common EELV upper stage.

I believe NASA is now looking at ACES as their new 5m CPS for their non-DUUS concepts.  Could they merge the concepts and have an ACES DUUS?
I've not heard that. I've only heard of an enlarged DCUS, which is not a bad idea either.
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SLS will be a fair bit longer than the AJAX core would be, so maybe that would create a stack height issue that AJAX would not have had?

That could be an issue, yes.
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Offline Lobo

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Re: AJAX Launcher
« Reply #1242 on: 07/19/2013 06:40 AM »
I've not heard that. I've only heard of an enlarged DCUS, which is not a bad idea either.

I don't know that it's ACES, just that in NASA's Option 1 and Option 2 from Chris's recent article on the DUUS, they are looking now at a 5m CPS, instead of the previous 7.5m CPS.  I'm only guessing it might be ACES as I know ULA was selling ACES in their recent paper on using EELV's for commercial crew.

I was making an assumption there, but I could be wrong.  It could be a stretched DCUS too, like Boeing had in their lunar gateway plan as the "in-space stage".

But, it got me thinking about perhaps a DUUS with more direct commonality with the EELV common upper stage.
« Last Edit: 07/19/2013 06:47 AM by Lobo »

Offline Downix

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Re: AJAX Launcher
« Reply #1243 on: 07/21/2013 10:22 PM »
I've not heard that. I've only heard of an enlarged DCUS, which is not a bad idea either.

I don't know that it's ACES, just that in NASA's Option 1 and Option 2 from Chris's recent article on the DUUS, they are looking now at a 5m CPS, instead of the previous 7.5m CPS.  I'm only guessing it might be ACES as I know ULA was selling ACES in their recent paper on using EELV's for commercial crew.

I was making an assumption there, but I could be wrong.  It could be a stretched DCUS too, like Boeing had in their lunar gateway plan as the "in-space stage".

But, it got me thinking about perhaps a DUUS with more direct commonality with the EELV common upper stage.
It sounded like the enlarged DCUS to me, barrel stretch to the existing DCUS systems.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline HappyMartian

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Re: AJAX Launcher
« Reply #1244 on: 07/22/2013 03:07 PM »
Someone suggested that we put the current configuration in the first entry, so here goes:

AJAX is a means of achieving the goals of the Congressionally mandated Space Launch System while reducing overhead costs by sharing resources with other United States launch systems. By studying the various Shuttle components, it was determined the optimal configuration would be to replace the existing pair of segmented solid rocket boosters with 2 pairs of liquid rocket boosters.  For cost, political and performance purposes, AJAX chose the ULA Atlas Common Core Booster (CCB).
....

Atlas CCB w/ nosecap (hard numbers):
dry weight: 21,844 kg
Fuel weight: 284,453 kg
....



This probably was considered previously, however:

The CCB or first stage of the Atlas V with its 1 RD-180 has a thrust 860,568 lbf and an Isp of 311 seconds at sea level.

In a vacuum its thrust is 933,400 lbf with an Isp of 338.
with a Burn time of about 253 seconds.

The RD-180 has 50 - 100% continuous throttling capability.

AJAX wouldn't have used solids. However, if NASA goes with the Dark Knights SRB's for the SLS, might it still make sense to have the option to eventually add two pairs of liquid boosters based on the Atlas CCB?

Wouldn't this be a somewhat cheap way to significantly enhance the performance of the SLS?

The RD-180s on the Atlas CCBs could be throttled down to about 50% prior to the ignition of the Dark Knights and 4 RS-25s, and then throttled up after Max Q.

The empty four CCBs would only add less than 100,000 kg to the SLS when moving it to the launch pad. The core would need minimal modification because the Dark Knights SRBs would still structurally 'hold up or stabilize the core and payload' prior to launch.

The RD 180s would need propellant cross feeds for an engine out option and normally might burn for around 5 minutes.
 
Would this modified AJAX-SLS be cheaper than adding a large and specialized J-2X stage and yet offer similar or greater performance gains?

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Offline Lobo

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Re: AJAX Launcher
« Reply #1245 on: 07/22/2013 05:43 PM »
It sounded like the enlarged DCUS to me, barrel stretch to the existing DCUS systems.

It certainly could be...but...

ULA wants ACES, correct?  They just need someone to pay for it.

An enlarged DCUS would leverage the existing DCUS, but in many ways, it'd be a new stage.  It would be supplied by ULA anyway.

If an enlarged DCUS is a new stage, and ULA wants money to make ACES and make it their new common upper stage, wouldn't it make sense to have ACES be the CPS?  ACES leverages existing systems too. 

Seems like ULA might want to make NASA a deal or bargin to develop their 5m CPS for them, and get ACES out of the deal, rather than an enlarged DCUS out of the deal, which probably won't be the common EELV upper stage. 

Online Robotbeat

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Re: AJAX Launcher
« Reply #1246 on: 07/29/2013 06:33 PM »
BTW, Downix, do you have those CAD models of the AJAX launcher? I'm going to see how far I can get in doing a little computational fluid dynamics... it's been a couple years, and I don't have access to the tools I had back in school (we used FEMLab, which was built on top of MATLAB, but now they changed the name to "COMSOL Multiphysics"...), but there are some interesting new tools out there for free... I'm going to see if I can import your model into GMSH (a free mesh-generator and post-processor), and then we'll see if we can get a solver working on it... (I have one in mind)

1) I'd like to suggest that you keep things simple and model each of the bodies as axisymmetric shapes.  You can refine the model later.

2) you'll need a solver which can handle transonic and supersonic flow.  I believe the two you mentioned, FEMLab and COMSOL, are incompressible.  But I could be wrong.

3)  Which code did you have in mind?

OpenFOAM (http://www.openfoam.com/) incorporates turbulence models but last time I looked, (1 yr ago?) the equations for the pertinent solvers listed on their web page were solved uncoupled so the solvers can not solve (or at least get good answers) for steady state transonic (past supercritical) and supersonic flow.  They mention having solvers for transient compressible flow, but you'll need to validate the results for supercritical flows by comparing test cases to literature.  And, be careful with that since some WT tests can be questionable for supercritical flows.  I'd recommend comparing to axisymmetric shapes rather than 2D shapes (airfoils).  However, still be VERY careful.  There is a solver AeroFOAM (http://www.aero.polimi.it/freecase/?OpenFOAM_%2B_Code_Aster:Download) which has the elements required to solve transonic/supersonic steady state flow, but I believe it lacks turbulence models.  Also, I don't know how up to date it is.  If you have questions about OpenFOAM a good place to ask is Symscape (http://www.symscape.com/) in addition to online forums.

Another code is FreeCFD, (http://www.freecfd.com/).  I think it has the elements required, but I'm not sure.  I'm also not sure if it is being actively developed.

As for all the rest, the majority are incompressible  (Solving the coupled equations is a pain) or they don't have a turbulence model (laminar only) or they are 2D.

4)  Later, you mentioned that you don't have a powerful workstation...  Your machine may not be able to handle this...  (note:  for multicore machines, the bottle neck is not the floating point computations (cpu) but the memory bus)

5)  A suggestion, you can look in literature and get the forebody drag on blunted cones and ogives.  Then kluge in skin friction and base drag.  For example you can get blunted cone information from NASA TN D-3088 "Aerodynamic Characteristics of Spherically Blunted Cones at Mach Numbers from 0.5 to 5.0" and skin friction and base drag from Hoerner's Fluid-Dynamic Drag.  This will get you CD0.  Then spot check your results against CFD.  And, for the time, ignore CL and CM for the trajectory.

Edit:
As the CCBs move closer to one another the interference drag for transonic and supersonic flow will increase.  You May need to kluge something in or model that region up in a CFD code.  Euler results may be a good first crack at it since you are looking for the pressure rise.  Of course you'll be neglecting viscosity, but at this point the approximation is probably ok.  Of course caution must be used.  If viscosity creates a recircularization region ahead of the CCBs, the real drag may be appreciatively lower than Euler result.

Soo.... I've been doing some more OpenFOAM modeling with a completely unrelated project, but I'm interested if you know of any progress in OpenFOAM. Specifically, I want to model something descending (subsonically) through a supercritical gas. The equations of state are beyond me, but I do want to know if there are tools available in OpenFOAM to solve this. Are you aware of any?
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Offline RocketmanUS

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Re: AJAX Launcher
« Reply #1247 on: 12/20/2014 07:38 PM »
RS-25's are not in production.
RD-180's are most likely not going to be used much longer in the U.S.
No advanced booster yet for SLS.

So how about having two boosters ( new Atlas V common core ) each with 2 or more BE-4's on them and a core powered by multiple BE-4's?

Core could be made with SLS vertical weld machine.

So I'm thinking three BE-4's on each booster and eight BE-4's on the core. Total of 7,700,000 lb at lift off.

US to use RL-10C's.

So could NASA have it's own HLV with commercial? Should have the potential to keep cost down.

The new Atlas V boosters could be the advanced boosters. The core and US could be the same ( manufacture and infrastructure ). Could have possible upgrades if needed like having four boosters ( infrastructure ).

Could be an AJAX like HLV.

Offline baldusi

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Re: AJAX Launcher
« Reply #1248 on: 12/21/2014 04:13 AM »
That ship sailed a long time ago. I will predict that SLS will be the last NASA designed rocket. If there even a need for it to be replaced, commercial companies will do it. NASA will focus on what's on top.

Offline clongton

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Re: AJAX Launcher
« Reply #1249 on: 12/21/2014 12:40 PM »
Agree. NASA has been pushed out of the rocket design business as predicted 5 years ago. Ajax has sailed into the sunset. DIRECT has sailed into the sunset. SLS is the Senate's one last gasp of denial as a NASA design/build launch vehicle. As soon as commercial resupply of the ISS became an official project, NASA was done as a rocket designer because it destroyed the price structure. Commercial can do the same thing for far less money. NASA will now focus, as you said, on payloads. NASA will become a mission designer and administrator.
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Offline A_M_Swallow

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Re: AJAX Launcher
« Reply #1250 on: 12/22/2014 02:29 AM »
Agree. NASA has been pushed out of the rocket design business as predicted 5 years ago. Ajax has sailed into the sunset. DIRECT has sailed into the sunset. SLS is the Senate's one last gasp of denial as a NASA design/build launch vehicle. As soon as commercial resupply of the ISS became an official project, NASA was done as a rocket designer because it destroyed the price structure. Commercial can do the same thing for far less money. NASA will now focus, as you said, on payloads. NASA will become a mission designer and administrator.

It is considerably easier for a few politicians on a Senate committee to reallocate parts of NASA's budget that to get both Houses to agree to increase NASA's budget.  If the SLS is to be cancelled have major programs waiting to receive the money.  Possibilities include lunar landers, Mars transfer vehicles and gateway spacestations.  In FY2016 these programs do not lots of money, just sufficient for a way and means study, but they do need a place name in the budget.

Offline ArbitraryConstant

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Re: AJAX Launcher
« Reply #1251 on: 12/26/2014 07:52 PM »
So I'm thinking three BE-4's on each booster and eight BE-4's on the core. Total of 7,700,000 lb at lift off.
Now you've done it. Once the spell is broken and we can talk about a high thrust hydrocarbon core, do boosters even make sense?

Offline Lobo

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Re: AJAX Launcher
« Reply #1252 on: 12/31/2014 06:07 PM »
So I'm thinking three BE-4's on each booster and eight BE-4's on the core. Total of 7,700,000 lb at lift off.
Now you've done it. Once the spell is broken and we can talk about a high thrust hydrocarbon core, do boosters even make sense?

That's exactly the point.  Unless you are talking a modular platform like Falcon or Delta (or Atlas if A5H had ever been developed) A unique core that needs different and unique boosters to fly doesn't make a lot of sense.  Completely different structures for the core and boosters, different engines, etc.  At that point, much better to go with a monolithic hydrocarbon.  One core, one booster engine.

If you are building a modular platform, than common core type boosters make sense.

Offline clongton

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Re: AJAX Launcher
« Reply #1253 on: 12/31/2014 07:53 PM »
NONE of this has anything to do with AJAX.
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I started my career on the Saturn-V F-1A engine

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