You start off with a false comparison. The SM has squat to do with mission capability, which is a function of the lander, so you've already dismantled the credibility of the argument.
Gaetanomarano, you are still insisting the small SM weighs only 10 mT and has only 7 mT of propellant. The equations indicate this is impossible, which I have attempted to show you on more than one occasion in another thread. Orion simply cannot produce the published delta-v out of only 7 mT of propellant. You are certainly entitled to your opinion and are free to write as many articles as you want, but please stop repeating figures that demonstrably wrong. Doing so only make you look dishonest. A more reasonable estimate is 13 mT total mass with 10 mT propellant.
however, the point of my comparison is NOT between 7 mT or 10 mT of propellant, but between "TEI-only propellant SM" (the "corks screw Orion") and "TEI+LOI propellant SM" (the "swiss knife Orion")
then, also if I accept your evaluation (10 mT of SM propellant) that doesn't change nothing of the question explained in my article (smallSM or bigSM?)
Based on the most recent information published by NASA, we know the following:
CM dry mass: 7,891 kg
CM launch mass: 8,485 kg
SM propellant: N2O4/MMH
SM delta-v: 1,855 m/s
This is enough information to make a fairly good estimate of the SM propellant load, which Mark Wade and I have already done. Those calculations show that 9.5 to 10 mT is a reasonable estimate. Your figure of 7 mT is simply not creditable.
- LOI of the Orion+SM alone
- LOI of the Orion+SM+LSAM
- TEI of the Orion+SM
- earth/lunar orbit maneuvering
- ISS/LSS orbital reboost
- earth/lunar orbit change
- earth reentry speed braking (optional)
and where are G's similar numbers?
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For LOI the mass varies from 66,000 kg to 51,480 kg (my numbers), therefore
G @ start of burn = 27,200/66,000 = 0.41 g
G @ end of burn = 27,200/51,480 = 0.53 g
During descent the mass varies from 30,480 kg to 19,845 kg, therefore
G @ start of burn = 27,200/30,480 = 0.89 g
G @ end of burn = 27,200/19,845 = 1.37 g (100% thrust)
Of course the engines won't be firing at 100% thrust near the end of the descent burn because they need only to counteract gravity so the LSAM can hover and set down gently. The "weight" of the LSAM in lunar gravity at touchdown will probably not be less than about 33 kN (unless we use gaetanomarano's downsized LSAM). Hovering will therefore require 1/8th thrust, or two engines at 25% thrust.
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.
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 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.
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.
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.
OK I am not in the same class as some of you guys - in that I can't to the math for propellant and thrust calculations. However if it were deemed necessary would it not be possible to develop a "stretched" Service Module for use on specific missions (where the lander could be eliminated). Surely most of the same components (engines, control systems, connections to the CM etc) could be re-used so surely an enlarged SM would not need to be designed from scratch were the need to arise, that after all should be the benefit of a modular design structure.
since you have evaluated an heavy standard-Orion, now you need that a J-2x Ares-I can lift it
but you can't change the NASA specs the way you want
LOGIC wants that NASA engineers have (simply) calculated the max upperstage mass at lift-off of every CLV configuration (the original table has six different rockets) and, since the LAS was estimated at 4 mT, they have subtracted that mass to have the max payload value of each configuration
now, with a 6.2 mT LAS, the payload can't remain the same but must have a cut of 2.2 mT + 0.6 mT for the interstage (another mass unknown when the table was made)
you CAN'T add 2, 4, 6, 8, 10 mT or more mass on the same rocket and have the same performances!
maybe, the rocket CAN fly with more upperstage mass, but NOT reach the same (planned) orbit
so, you're correct to say "nothing limiting the liftoff mass to 26 mT" only if you add "but the paylaod can't reach the same orbit"
sorry, but my premise/assumption are correct and your evaluations are wrongYour conclusions are incorrect because they are based on a flawed premise; that being your assumption the liftoff mass is limited to 26 mT.
if you want to match the Orion with the Ares, you must... reduce the Orion weight OR use a better Ares OR launch and dock the lunar convoy in a lower orbit
since (so far) we don't have any news about orbit change or different Ares' payload+LAS mass, the only way is to reduce the SM mass and/or the propellants' mass
your explanation is correct, I perfectly understand it and the rocket with 2+ mT extra mass may fly, but NOT reach the same orbit (however, you can ask NASA to change the planned orbit...)My explanation is absolutely correct; your inability to understand it seems to be the problem.
I prefer to see a REAL test and, anyway, the rocket may work with more upperstage mass but not reach the same orbit...the deliverable payload will be reduced to about 21.8 mT...
more SM mass can match the total Orion mass reducing the "extra" propellants' mass...no precedent to suggest a pressure-fed system of the size required can be fit into such a small package...
but it has effect on the total mass at TEI that has effect on the propellants' mass for TEI that has effect on the dimensions of the SM tanks that has effect on the SM dimensions that has effect on the SM mass......CM mass has no affect on how big the SM must be to house the required quantity of propellant...
I don't refer to your bigOrion calculations but to your standard-Orion calculations that is too heavy to be launched to the right orbit with the known Ares-I specsI don’t care about the Ares I. You’ve said you want to fly an Apollo-like mission to the Moon using an enlarged Orion SM. I’ve calculated approximately how large Orion needs to be to accomplish that mission. If it is too big to be lifted by the Ares I then that’s your problem.Originally Posted by gaetanomarano
but your specs need an Ares-I able to lift more payload mass than planned and (so far) we have not (real) evidence that it can
no, it's not, since my bigOrion is the BEST choice at EVERY final weight!...could be even worse news for your concept. The Shuttle OMS has an Isp of only 313 seconds...
also, we don't know how much "upgrade" LM will put in the SM engine (I suggest to wait for real data about this point instead of guess everyday a new figure)
true, in fact my SM evaluations have plenty of extra-propellants for maneuverings, emergency, redundancy, etc.We must design for the worst case.
the problem is that your (excessive) evaluations are for the TOO WORST CASE since your goal is to demonstrate that my proposals are flawed
when? in which forum/thread/post?I can find fault in ESAS...
I've never read any critics from you about ESAS... do you think it's perfect?
Last edited by gaetanomarano; 2006-Sep-25 at 04:20 PM. Reason: grammar
launch a bigOrion needs a miniEDS and two (enhanced) Ares-I (or one, bigger, Ares-II)
if the Ares-II will be designed and built now it may have an R&D costs similar to Ares-I and a reasonable hardware price per launch
but, if the only rockets built will be the (too small) Ares-I and the (too big) AresV, the only ways to launch a bigOrion will be:
1. design and build a third rocket (Ares-II) or...
2. launch the bigOrion with the AresV
and, since both options are TOO EXPENSIVE, the bigOrion will never fly!
Last edited by gaetanomarano; 2006-Sep-25 at 04:57 PM.