Author Topic: DIRECT v2.0 - Thread 4  (Read 79457 times)

Offline Crispy

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Re: DIRECT v2.0 - Thread 4
« Reply #180 on: 06/01/2009 03:24 pm »
needs to be on youtube. I can do this?
I already get lots of views to the previous version:

« Last Edit: 06/01/2009 03:26 pm by Crispy »

Offline Ben the Space Brit

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Re: DIRECT v2.0 - Thread 4
« Reply #181 on: 06/01/2009 03:25 pm »
When do we get an official Direct 3.0 Thread?

IIRC, Ross said that the new v.3.0 version of the website is scheduled for roll-out Tuesday or Wednesday.  The new thread will probably be started simultaneously with that.

Don't blow a gasket, TBW.  I'm sure there will be lots of other stuff there to justify the delay. ;)
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Offline gladiator1332

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Re: DIRECT v2.0 - Thread 4
« Reply #182 on: 06/01/2009 03:26 pm »
I agree on youtube...Direct should have its own Channel on there as well, just like Ares has theirs.


Offline Crispy

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Re: DIRECT v2.0 - Thread 4
« Reply #183 on: 06/01/2009 03:31 pm »
Ok. 3.0 video is uploaded:

« Last Edit: 06/01/2009 03:42 pm by Crispy »

Offline kraisee

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Re: DIRECT v2.0 - Thread 4
« Reply #184 on: 06/01/2009 03:33 pm »
TrueBlue, that's a good idea.   Give me some time, I'll get it done a little later today.

I'm still following-up on some stuff from the conference :)

Ross.
« Last Edit: 06/01/2009 03:34 pm by kraisee »
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Offline Danny Dot

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Re: DIRECT v2.0 - Thread 4
« Reply #185 on: 06/01/2009 03:46 pm »
Good suggestion Danny, I'll see about making an MPEG version.

And no, the LOX tank is sized to precisely the same capacity as the current ET's Ogive tank.

We do still have an option to increase the capacity of both the LOX and LH2 tanks by ~7-9% (in the same way as NLS was going to), but right now, mostly for simplicity sake, we have simply chosen not to mess around with altering the capacities.   We can close all performance requirements comfortably without it.

Ross.

Your video says "LOX tank extension".  This implies a bigger mod than you might be doing.  Are you just changing the shape of the end of the tank?

You might make a note of this for your next release. 

I would also be interested in the total weight on the pad of Shuttle and Jupiter 130.  Given they have the same engines and prop, the gross weight on the pad is probably the same.  This might be an easy way to show the performance of Jupiter 130 does NOT defy the laws of physics.

Danny Deger

P.S.  The MPEG 4 runs on both QuickTime and Windows Movie Player.  I think you have a file that will play on "anything"
Danny Deger

Offline kraisee

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Re: DIRECT v2.0 - Thread 4
« Reply #186 on: 06/01/2009 03:49 pm »
I have just created a new DIRECT v3.0 thread here:

http://forum.nasaspaceflight.com/index.php?topic=17295.0


This thread will remain open for a while still, in case there is discussion about the older version of DIRECT, but most discussion should move over now, please.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline luke strawwalker

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Re: DIRECT v2.0 - Thread 4
« Reply #187 on: 06/01/2009 07:54 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

Over on the Altair thread, Ross said that the LOI accounts for just over half the total descent stage mass for the LSAM. Interestingly, this makes it in the ballpark of an EELV upper stage. My idea, on hearing this, was to leave the EDS basically as-is, and split the LSAM into a three-stage vehicle- LOI, descent, ascent. An extra stage sounds like a bad idea but remember it would be an already flying stage, and if all goes to plan might be man-rated anyway as part of a LEO-servicing EELV.
As always in rocketry, it's a case of balancing the efficiency of added stages against their added complexity and costs.

More mass to push through TLI, which comes out of landed mass... a stage would weigh considerably more than the burned fuel for LOI in the LSAM tanks...

Now you WOULD gain some advantage back in smaller tankage on Altair, which would lower the landed mass back down, and make Altair lower to the ground and less top heavy.  I still think you'd come out on the losing side performance wise, but given the benefits of a smaller, lower LSAM it might be a worthwhile trade. 

OL JR :)
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Offline marsavian

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Re: DIRECT v2.0 - Thread 4
« Reply #188 on: 06/01/2009 07:59 pm »
I have just created a new DIRECT v3.0 thread here:

http://forum.nasaspaceflight.com/index.php?topic=17295.0


This thread will remain open for a while still, in case there is discussion about the older version of DIRECT, but most discussion should move over now, please.

Ross.

This older version may become the current one again if regen RS-68s are sanctioned ;).

Offline clongton

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Re: DIRECT v2.0 - Thread 4
« Reply #189 on: 06/01/2009 08:25 pm »
I have just created a new DIRECT v3.0 thread here:

http://forum.nasaspaceflight.com/index.php?topic=17295.0


This thread will remain open for a while still, in case there is discussion about the older version of DIRECT, but most discussion should move over now, please.

Ross.

This older version may become the current one again if regen RS-68s are sanctioned ;).

No - DIRECT v2.0 has "transcended the outer peace".
It is now of historic and academic interest only. All future discussion, including anything of that potential, will take place in the new thread.
« Last Edit: 06/01/2009 08:26 pm by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline jongoff

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Re: DIRECT v2.0 - Thread 4
« Reply #190 on: 06/02/2009 11:52 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.

Heh.  So my old joke about how "real lunar transfer vehicles deliver their payload all the way to lunar orbit, not just pansying out at TLI" actually bears up to physical reality?

~Jon

Offline gladiator1332

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Re: DIRECT v2.0 - Thread 4
« Reply #191 on: 06/03/2009 12:58 am »
And thus ends the shortest Direct thread of all time...haha ;)

Offline Sesquipedalian

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Re: DIRECT v2.0 - Thread 4
« Reply #192 on: 06/03/2009 01:48 am »
Maybe it should be merged with Thread 3.  I thought that Thread 3 had been closed prematurely anyway. :p

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