Quote from: clongton on 01/20/2009 08:07 pmWe are if the original specification called for the capability. Originally, Orion was to make only 2 burns of the SM engine; 1) orbital insertion (same as Shuttle) and then 2) orbit circularization. Now it has to make 3 because Ares-I can't get Orion to the point where it's 1st burn is orbital insertion. The SM's first burn completes the ascent and shuts down. Some time later, the 2nd burn does the orbital insertion. And later still, a 3rd burn circularizes the orbit. Originally Ares-I was supposed to drop Orion off high enough and fast enough that only orbital insertion and later circularization was required. Not being able to actually accomplish that is called underperforming.The SM has to perform an OMS-1-type insertion burn AND and OMS-2-type circularization burn? The original plan didn't call for a direct insertion trajectory?
We are if the original specification called for the capability. Originally, Orion was to make only 2 burns of the SM engine; 1) orbital insertion (same as Shuttle) and then 2) orbit circularization. Now it has to make 3 because Ares-I can't get Orion to the point where it's 1st burn is orbital insertion. The SM's first burn completes the ascent and shuts down. Some time later, the 2nd burn does the orbital insertion. And later still, a 3rd burn circularizes the orbit. Originally Ares-I was supposed to drop Orion off high enough and fast enough that only orbital insertion and later circularization was required. Not being able to actually accomplish that is called underperforming.
I just wanted to announce that the plans for the models of the J-120 & J-232 are now publicly available for download and construction. They can be found in three places (so far)Jon Leslie's Lower Hudson Valley Challenger Center website.http://www.jleslie48.com/gallery_models_real.htmlAs a side note, I find it immensely satisfying that they are listed under the "Real Spacecraft" section... Niels J. Knudsen's Paper Models sitehttp://www.nielspapermodels.comand the Yahoo Space Paper Models Group.http://groups.yahoo.com/group/Space-Paper-Models/I hope those of you who build them enjoy doing it as much as I did.Thanks
Could the Core be left in orbit, given that it will decay quickly?
The SM has to perform an OMS-1-type insertion burn AND and OMS-2-type circularization burn? The original plan didn't call for a direct insertion trajectory?
I just wanted to announce that the plans for the models of the J-120 & J-232 are now publicly available for download and construction.
They can be found in three places (so far)Jon Leslie's Lower Hudson Valley Challenger Center website.http://www.jleslie48.com/gallery_models_real.htmlAs a side note, I find it immensely satisfying that they are listed under the "Real Spacecraft" section...
Niels J. Knudsen's Paper Models sitehttp://www.nielspapermodels.com
and the Yahoo Space Paper Models Group.http://groups.yahoo.com/group/Space-Paper-Models/
I have a question regarding figures 20 & 21 from the V2.0.2 update doc (http://www.launchcomplexmodels.com/Direct/documents/DIRECT_Summary_v2.0.2.pdf).This shows LSAM performing MCC / TCM burns (I presume MCC is Mid Course Correction, not sure what TCM stands for). The diagram shows the Isp as 448s, so this is using the RL-10's in the descent stage.This burn is only 2m/s (a couple of seconds burn at minimum throttle, I think), so this seems like a pretty small burn to go through the whole complication of starting up the RL-10's.If not, what is the reason why LSAM performs this manouvre instead of CEV?
Quote from: MP99 on 01/21/2009 11:18 amI have a question regarding figures 20 & 21 from the V2.0.2 update doc (http://www.launchcomplexmodels.com/Direct/documents/DIRECT_Summary_v2.0.2.pdf).This shows LSAM performing MCC / TCM burns (I presume MCC is Mid Course Correction, not sure what TCM stands for). The diagram shows the Isp as 448s, so this is using the RL-10's in the descent stage.This burn is only 2m/s (a couple of seconds burn at minimum throttle, I think), so this seems like a pretty small burn to go through the whole complication of starting up the RL-10's.If not, what is the reason why LSAM performs this manouvre instead of CEV?Trajectory correction maneuverThis is how NASA planning and Direct is doing the same thing
After performing final ascent burn, orbital injection burn and orbital circularization burn, the remaining propellant in Orion's SM tanks needs to be reserved for the TEI burn to bring everybody home.
Quote from: clongton on 01/21/2009 12:26 pmAfter performing final ascent burn, orbital injection burn and orbital circularization burn, the remaining propellant in Orion's SM tanks needs to be reserved for the TEI burn to bring everybody home.It's only 2m/s !It's my understanding that hypergolic engines are extremely reliable, start very easily, and I'd have thought were quite throttle-able, too.Cryogenic engines have complex startup procedures, waste quite a bit of fuel spinning up their pumps, and the risk of non-starting or failure during operation is somewhat higher.A hypergolic engine seems to be absolutely ideal for this type of manouvre. Have I missed something (about suitability of that type of engine, not whether fuel happens to be available).As you've commented, if DIRECT is chosen Orion won't need to perform the ascent. Would it then make sense for NASA to use 2m/s of Orion fuel to perform the TCM/MCC burn? Does that have any appreciable effect on LOC/LOM numbers?cheers, Martin
Quote from: Lancer525 on 01/20/2009 10:14 pmI just wanted to announce that the plans for the models of the J-120 & J-232 are now publicly available for download and construction. ThanksThanks for posting them! I'll have to start building them once I can get some heavier paper. All I have in my room is computer paper, and that never works. What kind of glue do you recommend?
I just wanted to announce that the plans for the models of the J-120 & J-232 are now publicly available for download and construction. Thanks
Quote from: Lancer525 on 01/20/2009 10:14 pmI just wanted to announce that the plans for the models of the J-120 & J-232 are now publicly available for download and construction. An order to commence construction?...
Niels J. Knudsen's Paper Models sitehttp://www.nielspapermodels.comThe Direct models don't seem to be up there yet?
and the Yahoo Space Paper Models Group.http://groups.yahoo.com/group/Space-Paper-Models/Hmmm... members only.
Okay, I have the files from jleslie48.com and would just toss them up on the mirror as a directory of separate files and a .zip of the directory for convenience in downloading. In your notes with this release you spend quite some time explaining your sourcing but... no redistribution policy notice of your own?(Something simple like "Mirror these if you want to but keep the files together and please don't change things without notice." would be nice )
Only then - with some basic assumptions and a common ground for important input data - can such input data be implemented into several independent tools / simulators and only then can the discussion about eventual divergence / convergence of 'results' be something more fruitful…
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