Author Topic: DIRECT v2.0 - Thread 4  (Read 76060 times)

Offline kraisee

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Re: DIRECT v2.0 - Thread 4
« Reply #20 on: 05/22/2009 03:22 am »
It will be some serious time before the EPA takes a serious crack at the perchlorate issues of Shuttle SRB's, but it is something the program needs to keep in mind given that what we develop now will probably still be in use in 25+ years time.

There are two paths, as described above.   One is to change the mixture of the solid propellant.   The other is to replace the SRB's with a Kero-Lox system instead.

I personally think that the deciding factor will be the politics of the situation.   You would have the mother-of-all-battles trying to muscle ATK out of this business.   That's why I just can't see the SRB's going away.

Ross.
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Offline kraisee

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Re: DIRECT v2.0 - Thread 4
« Reply #21 on: 05/22/2009 03:35 am »
One of the best 'alternative' mission profiles which we have been able to confirm so far is that of using the EDS to perform the LOI as well as the TLI.

Because the lander doesn't have to perform the LOI, it results in a lander which is considerably smaller and lighter than the current CxP design.   This solves almost all of the Altair's height/stability issues and might even allow the thing to fit inside an 8.4m PLF again too.   At this size and mass the LSAM & CEV will *easily* fit on a J-130, thus improving both costs and safety for each mission.   Also by having multiple engines on an RL-10-powered EDS you get high Isp and a great deal of engine-out capability for the LOI as well, which is nice.

With this profile we're seeing about 10% extra payload mass to the Lunar surface as well -- and that's the real point.

Ross.

« Last Edit: 05/22/2009 04:32 am by kraisee »
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Offline kraisee

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Re: DIRECT v2.0 - Thread 4
« Reply #22 on: 05/22/2009 04:36 am »
A Question for the readership here:

Do you think I should make a "DIRECT Reference" thread here, specifically for storing the latest Baseball Cards, Mission Profile charts and other such material in one location that can be updated as and when required?

I would have the thread locked permanently, except for updates, so it wouldn't be an actual discussion thread, but it might be a useful "one-stop-shop" for all the latest information.

Thoughts?

Ross.
« Last Edit: 05/22/2009 04:37 am by kraisee »
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Offline Steven Pietrobon

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Re: DIRECT v2.0 - Thread 4
« Reply #23 on: 05/22/2009 05:33 am »
Yes, that would be great Ross. Would make finding the information you post that much easier.
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Offline TrueBlueWitt

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Re: DIRECT v2.0 - Thread 4
« Reply #24 on: 05/22/2009 05:41 am »
A Question for the readership here:

Do you think I should make a "DIRECT Reference" thread here, specifically for storing the latest Baseball Cards, Mission Profile charts and other such material in one location that can be updated as and when required?

I would have the thread locked permanently, except for updates, so it wouldn't be an actual discussion thread, but it might be a useful "one-stop-shop" for all the latest information.

Thoughts?

Ross.

I think I've heard that Idea somewhere before.. where could that have been? 

Needless to say.. I think it's a STELLAR idea that would get readers DIRECT(ly) to the point.
« Last Edit: 05/22/2009 05:43 am by TrueBlueWitt »

Offline zapkitty

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Re: DIRECT v2.0 - Thread 4
« Reply #25 on: 05/22/2009 06:36 am »
A Question for the readership here:

Do you think I should make a "DIRECT Reference" thread here, specifically for storing the latest Baseball Cards, Mission Profile charts and other such material in one location that can be updated as and when required?

I would have the thread locked permanently, except for updates, so it wouldn't be an actual discussion thread, but it might be a useful "one-stop-shop" for all the latest information.

Thoughts?

Ross.

You should do so, and link both the wiki Direct article and the directlauncher.com site to it while indicating that the latest data is to be found at that link.

Of course you could source it at any of the three and have the other two point to it...

Offline kraisee

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Re: DIRECT v2.0 - Thread 4
« Reply #26 on: 05/22/2009 07:38 am »
Another good solution is, of course, just to keep the website updated properly!   :)

And as of tonight, that is now in work as well...

Ross.
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Offline Finn

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Re: DIRECT v2.0 - Thread 4
« Reply #27 on: 05/22/2009 09:54 am »
Another good solution is, of course, just to keep the website updated properly!   :)
That was my first thought as well - why make a reference thread in the NSF forum, when the same kind of info should be easily available on the DIRECT web page. Might be double maintenance work.

Offline kcrick

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Re: DIRECT v2.0 - Thread 4
« Reply #28 on: 05/22/2009 12:02 pm »

I think the idea of a thread for draft baseball cards and other documents is a great idea !  But the final version of stuff should be on the DIRECT's website. I've often found myself going back thru the threads to try to locate a document I perused, wondering if it would be better just to have a thread dedicated to them.

Kevin
Kevin

Offline Stephan

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Re: DIRECT v2.0 - Thread 4
« Reply #29 on: 05/22/2009 12:08 pm »
Do you think I should make a "DIRECT Reference" thread here, specifically for storing the latest Baseball Cards, Mission Profile charts and other such material in one location that can be updated as and when required?

I would have the thread locked permanently, except for updates, so it wouldn't be an actual discussion thread, but it might be a useful "one-stop-shop" for all the latest information.

Thoughts?
It would be a very good idea, it's always difficult to find back those useful charts.
Or consider udpating the website as you said ;)
Best regards, Stephan

Offline padrat

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Re: DIRECT v2.0 - Thread 4
« Reply #30 on: 05/22/2009 12:36 pm »
I bet a lot of people would celebrate the removal of HCl from the exhaust and all the associated concerns (maintance of structures, water pollution etc.).

You'd get my vote. Would make a world of difference in pad securing after launch and maintenance. As far as going RP-1/LOX, well, for obvious reasons I'm an LH2/LOX man myself ;) but, hey, we've stored RP-1 out here as well at one time, wouldn't be an issue to do it again, well, other than the obvious (re-building the infastructure).


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Offline gospacex

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Re: DIRECT v2.0 - Thread 4
« Reply #31 on: 05/22/2009 12:37 pm »
Another good solution is, of course, just to keep the website updated properly!   :)

Ross.

Website should have "official" documents only, whereas a dedicated thread here can be used to keep drafts and such. It is equivalent to a cvs/svn/git tree in an open source software project, where anyone can download the latest code. You want as many people be able to see and comment on it as possible.
« Last Edit: 05/22/2009 12:39 pm by gospacex »

Offline clongton

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Re: DIRECT v2.0 - Thread 4
« Reply #32 on: 05/22/2009 12:52 pm »
I don't know. In theory it sounds like a good idea, but remember what this place is, and it's not a DIRECT site. In fact there are neutral and anti-DIRECT people here as well and they all have the right to have the same access as everybody else. Personally I don't think this would be a good precedent to set. We already post the latest stuff as it comes along and I think that is probably good enough as far as *this* site is concerned. I think a better idea would be to have two (2) places on the website for (1) official baseline documentation and (2) wip and interim documentation. Both tabs should be clearly marked so anyone going to the site would know exactly where to go to get what. Of course every time we post something new, we should provide a direct link to the document on the website.

Having one place where all the "in-transition" data is stored is a good idea, but I just don't think it's a good fit to ask Chris to manage that by locking and unlocking that thread. That's not his job and it's not the function of a discussion thread.

My 2 cents. ymmv
« Last Edit: 05/22/2009 12:55 pm by clongton »
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Offline kevin-rf

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Re: DIRECT v2.0 - Thread 4
« Reply #33 on: 05/22/2009 01:27 pm »

I would vote for a sticky note, latest baseball cards and performace numbers at a glance. And yes, keep it locked.

Not to get us off track, but if they get tough on perchlorate and stop using solids, I suspect Kero/Lox will end up being not used, not because of the science, but because of feel good political factors. Carbon emmisions, oh the horrors...
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Offline pierre

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Re: DIRECT v2.0 - Thread 4
« Reply #34 on: 05/22/2009 02:00 pm »
Not to get us off track, but if they get tough on perchlorate and stop using solids, I suspect Kero/Lox will end up being not used, not because of the science, but because of feel good political factors. Carbon emmisions, oh the horrors...

Just to keep things in perspective creating and keeping cold LH2 for a LH2/LOX stage causes much higher CO2 emissions than the drop in the ocean from a RP-1/LOX launch. And both pale compared to the CO2 emitted by NASA during routine operations (e.g. the employees' cars).

So, if ATK allows it and as a long term enhancement, switching from SRB to RP-1 boosters would be a big environmental improvement (not to mention a performance boost for Jupiter).

Offline strangequark

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Re: DIRECT v2.0 - Thread 4
« Reply #35 on: 05/22/2009 02:40 pm »
Not to get off track, but there's no other thread where this question would actually fit and it does fit this "current" discussion about replacing the SRBs on the Jupiter.
What's the power density of Methane vs. LNG vs. Kerosene?

If youíre talking energy density, the values for heat of combustion are as follows:

42 MJ/kg RP-1
47.5 MJ/kg CH4 (L)
109 MJ/kg H2(L)

LNG is largely methane. Not sure how much the higher hydrocarbons affect the value. The above is pretty rough, but comparable. Assumed that products were restricted to CO2 and H2O, with stoichiometric ratio. Oxidizer is taken as LOX. Heat of combustion was calculated as the difference between enthalpies of formation for reactants versus products. This doesnít take into account the energy required to raise the products to their final (exit, not chamber) temperature. If Iím feeling diligent, I might post that later, but that shouldn't change the qualitative difference too much. My bet is that itís pretty much a wash between the two, but RP-1 wins as a propellant choice in general because itís about twice the density, and the gains on Isp with methane probably arenít massive enough to offset that for a booster stage.
« Last Edit: 05/22/2009 03:02 pm by strangequark »

Offline kevin-rf

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Re: DIRECT v2.0 - Thread 4
« Reply #36 on: 05/22/2009 03:03 pm »
Not to get us off track, but if they get tough on perchlorate and stop using solids, I suspect Kero/Lox will end up being not used, not because of the science, but because of feel good political factors. Carbon emmisions, oh the horrors...

Just to keep things in perspective creating and keeping cold LH2 for a LH2/LOX stage causes much higher CO2 emissions than the drop in the ocean from a RP-1/LOX launch. And both pale compared to the CO2 emitted by NASA during routine operations (e.g. the employees' cars).


Yeah, but such reasonable logic fails on those who make such politically correct choices... AKA the current Ares ;)

If they go to the extreme and take away the solids, they will most likely go after Kero/Lox next.
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Offline guru

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Re: DIRECT v2.0 - Thread 4
« Reply #37 on: 05/22/2009 04:27 pm »
The Jupiter family next to a Delta-IV Heavy.

Offline padrat

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Re: DIRECT v2.0 - Thread 4
« Reply #38 on: 05/22/2009 05:19 pm »

Just to keep things in perspective creating and keeping cold LH2 for a LH2/LOX stage causes much higher CO2 emissions than the drop in the ocean from a RP-1/LOX launch.

Actually, keeping it cold doesn't cause anything. Now, steam-reforming it from LNG, chilling it, and transporting it here by truck, well....... you know. However, if there is a spill, there will be much less of an environmental impact from LH2 than from RP-1, provided that there isn't an explosion of course.
« Last Edit: 05/22/2009 05:23 pm by padrat »
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Offline PaulL

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Re: DIRECT v2.0 - Thread 4
« Reply #39 on: 05/22/2009 06:09 pm »
One of the best 'alternative' mission profiles which we have been able to confirm so far is that of using the EDS to perform the LOI as well as the TLI.

Because the lander doesn't have to perform the LOI, it results in a lander which is considerably smaller and lighter than the current CxP design.   This solves almost all of the Altair's height/stability issues and might even allow the thing to fit inside an 8.4m PLF again too.   At this size and mass the LSAM & CEV will *easily* fit on a J-130, thus improving both costs and safety for each mission.   Also by having multiple engines on an RL-10-powered EDS you get high Isp and a great deal of engine-out capability for the LOI as well, which is nice.

With this profile we're seeing about 10% extra payload mass to the Lunar surface as well -- and that's the real point.

Ross.


Ross, this looks like a very interesting configuration.  Having a JUS able to handle both TLI and LOI burns would probably also allow you to do a "full" Apollo-8 mission to any low lunar circular orbit with only one rocket.

PaulL

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