I don't know how much delta-v NASA has budgeted for TEI (it might be in the ESAS report but I've yet to see it). If we assume 1,000 m/s, which is about the average for Apollo, and an after TEI mass of 12 mT (its tanks won't be completely empty), then
Propellant = Mf*e^(dV/(Isp*g)) - Mf
TEI Propellant = 12*e^(1,000/(320.5*9.80665)) - 12 = 4.50 mT
Okay, who voted for the BigSM? Gaetanomarano?
Launchwindow. So sayeth the pollin' thing.
And somehow, Wolf-S voted small twice.
For example, one of the maneuvers was a plane change prior to LM ascent. This was necessary because, as the Moon rotated, the LM’s landing site would slowly move out of the plane of the CSM’s orbit. The CSM had to adjust its orbital plane so that its flight path once again passed over the landing site. The LM could then insert itself into the same orbital plane, which was required for rendezvous. The longer the LM was on the surface the more it moved out the CSM’s path, thus the greater the plane change. Plane changes require a lot of propellant; therefore the longer missions required more propellant.
here and the total Orion+SM mass at 21-21.5 mT here
you can't justify the giant 5 mT amount of extra propellants' mass (more than the TEI fuel!) with any exotic "maneuverings" since, at the end of a moon mission, the Orion must ONLY come back to earth!
it's interesting that (now) with a credible value for the lunar-SM propellants' mass (4.5 mT + 2 mT for redundancy) we can (also) evaluate the (possible) mass of an orbital-Orion for ISS with less propellant (but sufficient to reach the ISS, reboost, maneuverings, reentry, etc.)
I think that 2.0 mT + 0.5 mT for redundancy and maneuvering = 2.5 mT total is a reasonable value, so, the full orbital-Orion weight may be around 11.5 mT (Orion+SM dry mass) + 2.5 mT (propellants) + 6.2 mT (LAS) + 0.6 (2nd stage adapter) = 20.8 mT
and "20.8 mT" is close to the max payload (21 mT) of the latest (ATV) version of the Ariane5... then, an orbital-Orion can be launched (also) with an Ariane5 like I suggest in my June 30 article... (sorry, I'm right again...)
Last edited by gaetanomarano; 2006-Sep-22 at 10:04 PM. Reason: grammar
post #63). I didn’t perform the calculation four days ago because it wasn’t pertinent to the discussion at that time, but I clearly set forth the parameter upon which it is based. I calculated it today only because this is the first time it came up in the conversation.
and (exactly) 30 minutes after the NEOWatcher post......I calculated it today only because this is the first time it came up in the conversation.
the ONLY reason to add 5 mT of (useless and unused) propellants' mass in the SM tanks is to support the 5-segments SRB for the Ares-I (so it can lift 5 mT of dead-weight)I still stand by that calculation.
I really resent your insinuation; and if this forum didn’t have rules against it I’d let you know in no uncertain terms what I think of it.
sorry, I've only noted the coincidence...NEOWatcher hadn’t posted yet...
...not even for some "words" you write in this and other posts...if this forum didn’t have rules against it...
after so many posts about the SRB, you can't deny to be a supporter of the 5-segments SRB ....maybe, you are (only) "happy" to see it used in the new rockets......this comment is.
Last edited by gaetanomarano; 2006-Sep-22 at 11:38 PM. Reason: grammar
I have thought for some time now that these threads should all be in "against the mainstream".
As far as I can tell, the only thing keeping them out of "conspiracy theories" is that Gaetano has never actually addressed the fact that if NASA really were as incompetent and ignorant as he implies, there would pretty much have to be a conspiracy of epic proportions to keep it quiet.
I dunno about against the mainstream, you'd actually have to be swimming to pull that off, he's been flopping like foundered flounder through every thread on the Orion he's started.
On the other hand, it seems to me that your positions strongly imply that NASA is staffed by people who are incompetent and ignorant on a grand scale--so grand, in fact, that a conspiracy would be necessary to cover it up. But you never address this implication. Which is what keeps these threads out of the "conspiracy theories" section. Q.E.D.
Let me also point out that I’m an engineer and have spent years studying the science we’ve been discussing. As someone with professional credentials, I feel insulted when you imply I don’t know my business. Although you have been generally polite, it is not fair to play the innocent victim routine while claiming you haven't insulted anyone. What may not seem like an insult to you may be an insult to others.
Last edited by Bob B.; 2006-Sep-23 at 01:00 AM.
I've fiddled with the numbers and unless I'm totally wrong the 855 m/s "extra" delta-v can provide the Orion a plane change of 30 degrees at 100 km orbit. Doesn't seem all that much considering the angle from equatorial to polar orbit is 90 degrees.
I suspect most of that "extra" delta-v is budgeted for these plane change manouvers since the Project Constellation aims for high inclination landings. I'd say that the 5 mT of propellant, that gaetanomarano seems to think is dead-weight, will be very much needed.
Can anyone make educated guesses on what kind of plane change manouvers are required of the Orion vehicle?
And Gaetano, may I suggest you familiarize yourself with the Tsiolkovsky rocket equation to save much embarrassment.
Here is what the ESAS Report says about the CEV SM propellant:
Of course we know several changes have been made since this was written. The switch to N2O4/MMH propellant will result in a lower specific impulse. We've seen one article that said the AJ10-118K would be used, which has an Isp of 320.5 sec. And for comparison, the Apollo RCS had an Isp of 290 sec. The delta-V of the listed maneuvers total 1,724.4 m/s for the service propulsion system and 65.1 m/s for the RCS, for a combined total of 1,789.5 m/s. The most recent information released by NASA gives a revised delta-V of 1,855 m/s, however I don't know if the is the service propulsion system only or the SPS + RCS total. We also know there has been an overall mass reduction, so the mass listed in the report is outdated. There may be other changes as well that we don't know about.18.104.22.168 Lunar CEV SM
22.214.171.124.3 Subsystem Description
Propellant for the CEV SM consists of the following components:
- Used service propulsion system fuel propellant,
- Used service propulsion system oxidizer propellant,
- Used RCS fuel propellant, and
- Used RCS oxidizer propellant.
CEV total SM service propulsion system/RCS propellant is calculated for four major delta-V maneuvers in the mission. For each maneuver, the assumed service propulsion system Isp is 363.6 sec and the RCS Isp is 317.0 sec.
- The first major maneuver is rendezvous and docking with the LSAM in LEO. The CEV is inserted by the LV upper stage into a 55- x 185-km (30- x 100-nmi) elliptical orbit, while the LSAM and EDS are loitering in a 296-km (160-nmi) circular orbit. The CEV will then rendezvous with the LSAM and dock. The required delta-V for rendezvous and docking is estimated at 119.4 m/s for the service propulsion system and 25.1 m/s for the RCS, while the initial CEV mass prior to the maneuver is 23,149 kg.
- The second major maneuvers are station-keeping in LLO while the crew is on the surface and a contingency 5-deg plane change in the event of a worst-case anytime ascent from a 85-deg latitude landing site. The required delta-V for station-keeping is estimated at 15 m/s for RCS and 156 m/s of service propulsion system delta-V is included for the plane change. The initial CEV mass prior to these maneuvers is 21,587 kg.
- The third major CEV maneuver is TEI from LLO. For a worst-case anytime return from a polar orbit, a 90-deg plane change may first be needed to align the spacecraft’s velocity vector with the V-infinity departure vector. The method chosen to accomplish this maneuver is to use a sequence of three impulsive burns, where the first burn raises the CEV orbit apolune from a 100-km orbit to an orbit with a period of 24 hours. The CEV coasts to the correct position to perform the 90-deg plane change and then coasts to perilune to complete TEI. The required delta-V for TEI is estimated at 1,449 m/s for service propulsion system. This maneuver also includes +/–90-deg control of the arrival coazimuth at Earth and +/–12-hr control of the nominal 96-hr return time from the third TEI burn. The initial CEV mass prior to the maneuver is 21,057 kg.
- The fourth maneuver is a 10-m/s mid-course correction using an RCS. This is used to correct any errors resulting from an imprecise TEI burn. The initial CEV pass prior to the maneuver is 14,023 kg.
- The fifth and final SM maneuver is to safely dispose of the SM after CM separation. The required RCS delta-V for disposal is 15 m/s, and the initial SM mass prior to the burn is 4,372 kg.
I don't need to "design, build and launch" the objects I propose since I'm not an enginner and (also) I don't need to do the job that NASA and space companies must do
for me, it's sufficient to know (with sufficient accuracy) if my idea can work or not
having more time I can learn everything, but I don't need (nor have time) to do that
I have not a space company and I don't build rockets, then, I don't need to calculate all details of a vehicle
but, (e.g.) also if I will start a space company, I don't need to calculate or design anything
in every (space or not space) company there are many functions: managers (that do decisions without calculate nothing) "architects" of products (that may know all about calculations and design or only something or nothing) and the engineers that MUST know ALL about calculations, design, tests, etc.
to remain in the example, I'm like an "architect" and I can't be (not I need to be nor I can become in "ten easy lessons") an engineer
a practical example is the bigOrion
I don't need to design it, nor calculate all details of the hardware and of its mission
I only need to know that (with only 4.5 mT of propellants for TEI, 16 mT for LOI, etc.) my idea is feasible, nothing more, nothing less
if NASA or LM or ESA will decide to build (e.g.) the bigOrion, can (simply) use their army of engineers to do that job
Last edited by gaetanomarano; 2006-Sep-23 at 06:19 AM.
also, I've read (so far) that all maneuverings (including the change of orbit) must be done with LSAM engines
(so far) I've read that CEV engine has only two functions: TEI burning ath the end of mission and an EMERGENCY (and remote-controlled) change of orbit to dock with the LSAM if the latter has problems to reach the CEV
for these jobs, 4.5 mT or propellants (for TEI) and 2 mT of propellant (for extra maneuvering and redundany) are more than sufficient
the giant quantities of the ESAS plan's CEV was due (only) to the bigger CEV/SM in its first version (but now it's unnecessary)
of course, we can discuss of the orbital change option, but knowing that it is not part of the "plan"
about this point, you can read my reply to Bob B. post...Tsiolkovsky rocket equation...
Sadly the scenario I describe above is exactly want you are doing. You are refusing the calculations and opinions of people with real expertise in the area of rocket science simply because what they are telling you conflicts with your opinion. If you are not going to take the time to learn the science for yourself, then you have not earned the right to tell the experts they are wrong.
Gaetanomarano, when your opinion is at odds with reality it is time to change your opinion. The physical world is under no obligation to conform to your expectations.
Last edited by Bob B.; 2006-Sep-23 at 06:40 PM.