Orion gets to LEO using about half of a FH capacity.A lander would be similar on a 2nd launch. Then on a 3rd launch, the hydrolox EDS is put into LEO. It can't be much more than 50mt fully fueled, and the lander can't be too large or it won't be able to push Orion plus the lander through TLI.
{snip}Note:Propellants to fill both ACES and the Lunar lander already in LEO.For a better Lunar program use an OTV ( commercial designed and made ) instead of Orion.
Quote from: RocketmanUS on 07/09/2013 11:59 pm{snip}Note:Propellants to fill both ACES and the Lunar lander already in LEO.For a better Lunar program use an OTV ( commercial designed and made ) instead of Orion.We do not have a propellant depot so launching the fuel (and possibly the depot) needs including in the plan.An Orion is needed to re-enter to the Earth's surface from EML-1/2 or low lunar orbit. An OTV able to do this would be a significant extra expense - although a Dragon may be able to do it.
....And the Lunar lander can be kept at EML1/2, refueled at a depot there supplied by an ACES tanker.....4 ) EML1/2 way station ( helps test out long and deep space radiation protection testing ), used to store propellants, OTV, and Lunar lander(s)5 ) ect.What we need in the launchers is cheaper ( reusable ) and wide body fairing when needed.
I think the chart attached below (from the Delta IV Launch Services User‘s Guide, June 2013) is current, and the one upon which you would want to base speculation...
D4H could definitely be upgraded, but at great cost. It may have better TLI performance than Falcon Heavy when upgraded.It'd be expensive, but it's a good backup to a lunar architecture that relies on Falcon Heavy. Having both possibilities allows you to reduce technical risk while also being able to use the cheaper option if it works out. For instance, upgrading D4H shouldn't take as long as, say, developing a new lunar lander, so if you started now and SpaceX canceled Falcon Heavy in three years, it'd cost you more, but it wouldn't otherwise have to impact schedule too much (presuming you have a flexible architecture).
Quote from: Robotbeat on 07/10/2013 01:14 pmD4H could definitely be upgraded, but at great cost. It may have better TLI performance than Falcon Heavy when upgraded.It'd be expensive, but it's a good backup to a lunar architecture that relies on Falcon Heavy. Having both possibilities allows you to reduce technical risk while also being able to use the cheaper option if it works out. For instance, upgrading D4H shouldn't take as long as, say, developing a new lunar lander, so if you started now and SpaceX canceled Falcon Heavy in three years, it'd cost you more, but it wouldn't otherwise have to impact schedule too much (presuming you have a flexible architecture).If SLS went belly up how many of the potential missions in visioned for it could be performed by evolved versions of the D4H for example?
So I think using D4H might actually be a closer thing to be a reality than FH. But maybe I'm wrong there.
Quote from: Lobo on 07/09/2013 07:08 pmSo I think using D4H might actually be a closer thing to be a reality than FH. But maybe I'm wrong there. Delta IV Heavy could support a lunar mission, but it wouldn't have to be done in a surge or in a hurry. With a propellant depot, either a low-loss depot or a space-storable propellant depot, one Delta IV Heavy launch every three months - using only the existing launch pad - could support a human lunar landing every other year. This using the already-developed rocket with minimal changes. It is already the world's most capable rocket, why spend big bucks changing it? Why not use it? Spend the money on the lander and depot instead. - Ed Kyle
If SLS went belly up how many of the potential missions in visioned for it could be performed by evolved versions of the D4H for example?
Let's assume a cost of $150 for a Delta IV-H.
Since we have no real idea what SLS is going to cost per launch, we will have to speculate on this even further. NASA says $500 million per launch. Let's go with $750 million for a Block 1 and $1 billion for a Block 2 in case they botched the estimate.
Quote from: newpylong on 07/11/2013 01:45 amLet's assume a cost of $150 for a Delta IV-H.The average cost of an EELV launch, all costs included, was recently reported to be something like nearly $470 million. Since Delta IV Heavy is the largest variant, we can guess that it must cost a lot more than $470 million. QuoteSince we have no real idea what SLS is going to cost per launch, we will have to speculate on this even further. NASA says $500 million per launch. Let's go with $750 million for a Block 1 and $1 billion for a Block 2 in case they botched the estimate.At NASA's projected rate of one launch every two years, and given the proposed annual budgets of the program, it is possible to figure that an SLS mission, all costs included, is going to cost something like $6 billion, or maybe more, and that doesn't get astronauts onto the lunar surface.The advantages of a Delta IV Heavy include cost leveraging via. shared overhead and an ability to more easily meter the costs by spreading out the missions. No matter what, a lunar mission is going to cost a mountain of money. Each lunar landing might cost as much as two or three of the data centers the NSA is building to spy on its own citizens, for example. Or as much as 1/10th of an ISS. Etc. (Wild guesses both, but ballpark.) Or we could just keep spending billions each year on NASA like we currently are with no indigenous human program to show for it except for ISS Soyuz hitchhiking. - Ed Kyle
I think the chart attached below (from the Delta IV Launch Services User‘s Guide, June 2013) is current ...http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=32324.0;attach=532976
The advantages of a Delta IV Heavy include cost leveraging via. shared overhead and an ability to more easily meter the costs by spreading out the missions. No matter what, a lunar mission is going to cost a mountain of money. Each lunar landing might cost as much as two or three of the data centers the NSA is building to spy on its own citizens, for example. Or as much as 1/10th of an ISS. Etc. (Wild guesses both, but ballpark.) Or we could just keep spending billions each year on NASA like we currently are with no indigenous human program to show for it except for ISS Soyuz hitchhiking.
That is not a fair analogy. Program overhead costs were not factored into my numbers because a proper comparison would have them as their own line item and they would be shared by multiple launches.It was a comparison of vehicle and launch costs and only that. You can't keep adding $6 Billion dollars to every SLS launch cost in the same way you can't add the EELV infrastructure subsidies or development costs onto each launch. As of a few years ago, the EELV type dual-provider / dual infrastructure is an upwards of $1.2 Billion dollar recurring yearly cost comprised of actual launch effort and, significantly, of simply maintaining the productive infrastructure.
I think the chart attached below (from the Delta IV Launch Services User‘s Guide, June 2013) is current, and the one upon which you would want to base speculation.I believe an impressive human mission to the lunar surface -- possibly rivaling a Cx lunar sortie -- is possible using a total of four DIV-H launchers, each with the "easiest" upgrade (the addition of solid boosters).
Quote from: newpylong on 07/11/2013 03:49 amThat is not a fair analogy. Program overhead costs were not factored into my numbers because a proper comparison would have them as their own line item and they would be shared by multiple launches.It was a comparison of vehicle and launch costs and only that. You can't keep adding $6 Billion dollars to every SLS launch cost in the same way you can't add the EELV infrastructure subsidies or development costs onto each launch. As of a few years ago, the EELV type dual-provider / dual infrastructure is an upwards of $1.2 Billion dollar recurring yearly cost comprised of actual launch effort and, significantly, of simply maintaining the productive infrastructure.Fixed costs seem to represent the majority of costs for these machines these days. Those are real dollars paid by the government, no matter how they are sliced. Ignoring those dollars seems illusory and even deceptive. I believe it is more useful to try to contemplate real, rather than blue sky, costs. - Ed Kyle
For this thread if we want to use the DIVH and or the FH propellant depots and or propellant tankers are best to use, not launches direct to the moon. Nor is it a good idea to up grade the DIVH with SRB's and cross feed, unless the DoD required such lift capacity ( FH should end up being cheaper than DIVH is now before any upgrades would be put in place ).
Quote from: RocketmanUS on 07/10/2013 05:20 amFor this thread if we want to use the DIVH and or the FH propellant depots and or propellant tankers are best to use, not launches direct to the moon. Nor is it a good idea to up grade the DIVH with SRB's and cross feed, unless the DoD required such lift capacity ( FH should end up being cheaper than DIVH is now before any upgrades would be put in place ). For this thread, I was more interested in the ability of an upgraded D4H to throw payload through TLI, given it's superios BLEO capability compared to F9/FH.And doing a LOR architecture. Most concepts of using EELV-class LV's do a lot of LEO construction and then shoot a stack through TLI. That can be done, I was just wondering if an evolved D4H could shoot 20-25mt payload through TLI, if that would be a good size for a 3-element mission. Orion, Lander, crasher stage. Orion's about 20-21mt, an ACES -41 with no payload should get to lunar orbit with enough propellant left to do a staged descent for a lander, and the lander would be sized for that. A single stage lander like the Boeing lander would be what I'm picturing in my head here. If you are wanting to stage in LEO, and develop a new large EDS to shoot the whole stack through TLI, then FH is probably the better choice because it will come out of the gate with the LEO capacity of an evolved D4H...and likely be cheaper. But...it needs a new large hydrolox EDS. As SpaceX likely won't develop that, NASA would have to and integrate it themselves onto FH at KSC, and launch from there. So my main thought was, if you upgraded D4H with ACES and six GEM-60's, can you utilize it's great BLEO throw capacity directly? ANd would that be better than FH and a new hydrolox EDS staging in LEO?There's lots of thread about using EELV class LV's for a lunar program, in this I am more asking about the merits of using an upgraded D4H to shoot payloads directly to lunar orbit vs. staging in LEO with FH.
Quote from: sdsds on 07/10/2013 05:47 amI think the chart attached below (from the Delta IV Launch Services User‘s Guide, June 2013) is current ...Are there more specific LEO figures available?
I think the chart attached below (from the Delta IV Launch Services User‘s Guide, June 2013) is current ...
Quote from: sdsds on 07/10/2013 05:47 amI believe an impressive human mission to the lunar surface -- possibly rivaling a Cx lunar sortie -- is possible using a total of four DIV-H launchers, each with the "easiest" upgrade (the addition of solid boosters).I think the "easiest" upgrades would be both the solid boosters, and new upper stage. Specificaly ACES.
I believe an impressive human mission to the lunar surface -- possibly rivaling a Cx lunar sortie -- is possible using a total of four DIV-H launchers, each with the "easiest" upgrade (the addition of solid boosters).
Personally, with MHLVs like Delta-IVH and FH, I usually use a three-launch program.1) Mission vehicle (either a lander or Cygnus-derived LTV);2) Propulsion module (DEC-derived propulsion unit or ACES)3) Crew vehicle
Quote from: Lobo on 07/11/2013 05:00 pmQuote from: sdsds on 07/10/2013 05:47 amI believe an impressive human mission to the lunar surface -- possibly rivaling a Cx lunar sortie -- is possible using a total of four DIV-H launchers, each with the "easiest" upgrade (the addition of solid boosters).I think the "easiest" upgrades would be both the solid boosters, and new upper stage. Specificaly ACES.Yes, an ACES-like upper stage would be great! But its development will be more costly, and involve more cost and schedule risk, than slapping flight-proven GEMs onto the flight-proven DIV-H.
You're spinning this how you want. I didn't say ignore the cost - I said different line. You're calculation of launch cost had the SLS vehicle/launch cost + program overhead costs added onto to EACH launch, which is just wrong. Of course it's real money, but it's split among launches. The same can be said about the EELV subsidy (regardless of who pays for it).
I don't think DIVH can just add GEM's, I think the boosters need attach points added to them plus other thinks to make that work.
We really don't need to upgrade the DIVH for a Lunar program. We need the hardware for the Lunar program that will fit on DIVH and or FH.
we need to focus on LEO assembly and departure(s) ( cargo and for crew ). That will keep as flexible for the long run for multiple types of BLEO missions and let us use our current global launch fleet.
Quote from: RocketmanUS on 07/11/2013 07:11 pmI don't think DIVH can just add GEM's, I think the boosters need attach points added to them plus other thinks to make that work.Yes, and ULA seems to completely understand the work required. Essentially it's a non-issue, with highly predictable cost and schedule impacts. ACES? It's anybody's guess whether that work could be brought in on time and within budget, were there to be a customer who asked for it.QuoteWe really don't need to upgrade the DIVH for a Lunar program. We need the hardware for the Lunar program that will fit on DIVH and or FH.With enough LEO assembly, yes that would work.Quotewe need to focus on LEO assembly and departure(s) ( cargo and for crew ). That will keep as flexible for the long run for multiple types of BLEO missions and let us use our current global launch fleet.To whom do "we" and "our" refer?NASA is currently on a path to demonstrate cis-lunar rendezvous capability with SLS and Orion. A reasonable "compromise" would be to use SLS for Orion, and pre-place all other assets with Delta, Atlas, and Falcon.
Or if Elon wasn’t interested we could send a lander on Delta IV Heavy and a crew on a BEO CST-100 on an Atlas V...
Quote from: Rocket Science on 02/19/2014 07:45 pmOr if Elon wasn’t interested we could send a lander on Delta IV Heavy and a crew on a BEO CST-100 on an Atlas V...An upgraded Delta IV Heavy with ACES and GEMs could lift 45 tons to LEO, that could probably get a BLEO modified CST-100 on TLI in a single launch.
The reasoning behind this is that the DoD is/was not interested in certifying the Delta IV Heavy and that the Atlas V is being certified for human space flight... Unless they change their mind of course....
Quote from: Rocket Science on 02/19/2014 08:08 pmThe reasoning behind this is that the DoD is/was not interested in certifying the Delta IV Heavy and that the Atlas V is being certified for human space flight... Unless they change their mind of course....DOD has no role in certifying either launch vehicle for HSF.
Wait a sec--we should question one of the premises of this thread, placing SRMs on a D-IVH. AIUI, the cores for the D--IV family are all unique, with each of the three cores of the heavy specifically farbicated, and the core for the D-IV M yet another unique core. And it's taken years and effort to reduce the number of unique cores to this point. As such, to place SRMs on any of these in a heavy config would require another (three?) unique cores. The implications for the existing fleet, and the notional new fleet are problematic, and I'm sure the USAF and other govt agencies might have a say....
Yeah, I kind of assumed that if we're going back to the Moon, it doesn't make sense to repeat Apollo at all. The lander should be primarily just a transport. Land bulky cargo in separate trips from the crew. Spend most the time in a pressurized rover or a base or something, not camping out in the taxi. This reduces the requirements for the lander significantly (or allows it to carry a lot more people).
Quote from: Robotbeat on 02/19/2014 07:09 pmYeah, I kind of assumed that if we're going back to the Moon, it doesn't make sense to repeat Apollo at all. The lander should be primarily just a transport. Land bulky cargo in separate trips from the crew. Spend most the time in a pressurized rover or a base or something, not camping out in the taxi. This reduces the requirements for the lander significantly (or allows it to carry a lot more people).And...if mining, you have to get tonnage back to Earth!I think at that point, they'll have to figure out a method of in-situ refueling. There's probably few ores that will be worth sending back in some form that will require a lot of processing to separate out waste to get to. Just too expensive propulsively.Maybe some big chunks of gold or platium that can just be loaded into a cargo carrying ERV, but I think little else would be valuable enough to move without feasible in-situ refueling. (imagine finding a crater made by a several mt asteroid with a gold core or something...heheh Gold rush!)
Using Falcon Heavy for a lunar mission has been talked about before, and I think it'd be a viable LV for a 3-launch architecture.But I don't hear Delta IV-Heavy talked about much. And I mean the upgraded version of it. I've attached a D4H groth chart. It looks like with a new upper stage, two GEM-60's on each stage, and cross feeding, it can get up about 50mt to LEO. Now, FH can get that too with crossfeed. But what I think gets forgotten with D4H, is it can push a very large percentage of it's LEO capacity to GTO or TLI. I'm not sure of it's TLI capacity, but it can push over half of it's LEO capacity to GTO, where FH is about 22% of it's LEO capacity to GTO.So, would an upgraded D4H still be able to push half or more of it's LEO capability through GTO? ANd would it's TLI be similar to it's GTO?
Quote from: Lobo on 07/09/2013 07:08 pmUsing Falcon Heavy for a lunar mission has been talked about before, and I think it'd be a viable LV for a 3-launch architecture.But I don't hear Delta IV-Heavy talked about much. And I mean the upgraded version of it. I've attached a D4H groth chart. It looks like with a new upper stage, two GEM-60's on each stage, and cross feeding, it can get up about 50mt to LEO. Now, FH can get that too with crossfeed. But what I think gets forgotten with D4H, is it can push a very large percentage of it's LEO capacity to GTO or TLI. I'm not sure of it's TLI capacity, but it can push over half of it's LEO capacity to GTO, where FH is about 22% of it's LEO capacity to GTO.So, would an upgraded D4H still be able to push half or more of it's LEO capability through GTO? ANd would it's TLI be similar to it's GTO?No. Current Delta IVH is not "good for high energy orbits", its "bad for low energy orbits".And the reason why it's bad for low energy orbits is too low thrust of it's second stage. (second stage gravity losses with big payload)
Quote from: hkultala on 02/20/2014 05:18 amQuote from: Lobo on 07/09/2013 07:08 pmUsing Falcon Heavy for a lunar mission has been talked about before, and I think it'd be a viable LV for a 3-launch architecture.But I don't hear Delta IV-Heavy talked about much. And I mean the upgraded version of it. I've attached a D4H groth chart. It looks like with a new upper stage, two GEM-60's on each stage, and cross feeding, it can get up about 50mt to LEO. Now, FH can get that too with crossfeed. But what I think gets forgotten with D4H, is it can push a very large percentage of it's LEO capacity to GTO or TLI. I'm not sure of it's TLI capacity, but it can push over half of it's LEO capacity to GTO, where FH is about 22% of it's LEO capacity to GTO.So, would an upgraded D4H still be able to push half or more of it's LEO capability through GTO? ANd would it's TLI be similar to it's GTO?No. Current Delta IVH is not "good for high energy orbits", its "bad for low energy orbits".And the reason why it's bad for low energy orbits is too low thrust of it's second stage. (second stage gravity losses with big payload)In terms of per second, your greatest gravity loss per second is at lift off where rocket has the most mass.In terms per 60 seconds, the first 60 seconds from lift off is greatest gravity losses per minute of the trajectory. And opposite side of spectrum is when reach orbital speed [or escape velocity] thereafter regardless of mass of rocket you have zero gravity loss.And before reach orbital [or escape velocity] once attain large portion of the orbital [or escape] velocity their reduction in gravity loss [some kind gradient which coming down to zero]. And in addition, once get significant distance from earth, one simply has less gravity. Though if less 200 km distance from earth surface fairly it's insignificant. So at 200 km escape velocity is 11.009 whereas sea level it's 11.180 km/sec. Or gravity somewhere around 9.7 m/s/s vs 9.8 m/s/s so less than 200 km is less than 10% difference. So needs several hundred of kilometer distance before it becomes much of issue- but it's factor, but generally a much bigger factor would the velocity one would be going by time reach 200 km elevation.So I am looking at:http://spacecraft.ssl.umd.edu/design_lib/Delta4.pl.guide.pdfPage number 2-5 or PDF page 52.From this I would guess by time 50 seconds after lift off the delta-IV Heavy is going 137 m/s and by time it reach max dynamic pressure at the 86 seconds after lift off it would going around 300 m/s.And considering it's 249 seconds before two side rockets are staged, at 86 second mark rocket still has more than 2/3rd of it's mass. So it's mass starts with 733,400kg and 2/3rds is 491 tonnes.So since it's velocity is about 1/25th of orbital velocity, one can ignore that velocity, and so it's essentially like hovering about 500 tonnes for 86 seconds. Or in terms velocity, like dropping something in 9.8 m/s/s of gravity for 86 seconds which would gain velocity of 842.8 m/s. So that gravity lose of about .84 km/sec or around half of gravity loss of it getting to orbit.And it seems in remaining 163 seconds which gets to the point of "Two strap-ons cutoff" most of other half of gravity loss of the trajectory will occur.And it seems beyond the 249 seconds to 347 second- or next 98 seconds, you don't as much mass and you going significant fraction of orbital [or escape] vehicle, so gravity loss would less 10% of total gravity loss. So by time of second stage ignition at 349 seconds after lift off to until cutoff at 873 second, there is524 seconds, but don't think there is much gravity loss during those 524 second because it's already attained high velocity.
Quote from: gbaikie on 02/20/2014 01:06 pmQuote from: hkultala on 02/20/2014 05:18 amQuote from: Lobo on 07/09/2013 07:08 pmUsing Falcon Heavy for a lunar mission has been talked about before, and I think it'd be a viable LV for a 3-launch architecture.But I don't hear Delta IV-Heavy talked about much. And I mean the upgraded version of it. I've attached a D4H groth chart. It looks like with a new upper stage, two GEM-60's on each stage, and cross feeding, it can get up about 50mt to LEO. Now, FH can get that too with crossfeed. But what I think gets forgotten with D4H, is it can push a very large percentage of it's LEO capacity to GTO or TLI. I'm not sure of it's TLI capacity, but it can push over half of it's LEO capacity to GTO, where FH is about 22% of it's LEO capacity to GTO.So, would an upgraded D4H still be able to push half or more of it's LEO capability through GTO? ANd would it's TLI be similar to it's GTO?No. Current Delta IVH is not "good for high energy orbits", its "bad for low energy orbits".And the reason why it's bad for low energy orbits is too low thrust of it's second stage. (second stage gravity losses with big payload)In terms of per second, your greatest gravity loss per second is at lift off where rocket has the most mass.In terms per 60 seconds, the first 60 seconds from lift off is greatest gravity losses per minute of the trajectory. And opposite side of spectrum is when reach orbital speed [or escape velocity] thereafter regardless of mass of rocket you have zero gravity loss.And before reach orbital [or escape velocity] once attain large portion of the orbital [or escape] velocity their reduction in gravity loss [some kind gradient which coming down to zero]. And in addition, once get significant distance from earth, one simply has less gravity. Though if less 200 km distance from earth surface fairly it's insignificant. So at 200 km escape velocity is 11.009 whereas sea level it's 11.180 km/sec. Or gravity somewhere around 9.7 m/s/s vs 9.8 m/s/s so less than 200 km is less than 10% difference. So needs several hundred of kilometer distance before it becomes much of issue- but it's factor, but generally a much bigger factor would the velocity one would be going by time reach 200 km elevation.So I am looking at:http://spacecraft.ssl.umd.edu/design_lib/Delta4.pl.guide.pdfPage number 2-5 or PDF page 52.From this I would guess by time 50 seconds after lift off the delta-IV Heavy is going 137 m/s and by time it reach max dynamic pressure at the 86 seconds after lift off it would going around 300 m/s.And considering it's 249 seconds before two side rockets are staged, at 86 second mark rocket still has more than 2/3rd of it's mass. So it's mass starts with 733,400kg and 2/3rds is 491 tonnes.So since it's velocity is about 1/25th of orbital velocity, one can ignore that velocity, and so it's essentially like hovering about 500 tonnes for 86 seconds. Or in terms velocity, like dropping something in 9.8 m/s/s of gravity for 86 seconds which would gain velocity of 842.8 m/s. So that gravity lose of about .84 km/sec or around half of gravity loss of it getting to orbit.And it seems in remaining 163 seconds which gets to the point of "Two strap-ons cutoff" most of other half of gravity loss of the trajectory will occur.And it seems beyond the 249 seconds to 347 second- or next 98 seconds, you don't as much mass and you going significant fraction of orbital [or escape] vehicle, so gravity loss would less 10% of total gravity loss. So by time of second stage ignition at 349 seconds after lift off to until cutoff at 873 second, there is524 seconds, but don't think there is much gravity loss during those 524 second because it's already attained high velocity. 5m DCSS burn time is 1125s, not 524 seconds.For LEO mission, practically all of that is needed to reach orbit.
5m DCSS has 3 km/s delta-V for 25t payload (there is no official info how much the new RS68A-version lifts)So it's accelerating from 4.5km/s to 7.5km/s, so in average the velocity will be less than 6km/s (due acceleration being slower when it it more full). 6km/s velocity means gravity loss is about 20% of the gravity loss when stationary.So total gravity loss during the second stage is close to 9.81 * 0.2 * 1125 = 2.2 km/s
2.2 km/s is really considerable loss, compared to falcon heavy:
(imagine finding a crater made by a several mt asteroid with a gold core or something...heheh Gold rush!)
I know this is slightly off topic but I'd like to know how Atlas V, Delta IV and Falcon 9 split overall delta-v between first and second stages. Is the rule of thumb 4.5 km/s for the first stage and 3 km/s for second stage ?
Quote from: hkultala on 02/21/2014 12:19 pm5m DCSS burn time is 1125s, not 524 seconds.For LEO mission, practically all of that is needed to reach orbit.I was referring to pg 52 of above PDF where there is chart which says:"349 time (secs) 129 altitude (km) 0.23 Acceleration (g) Stage II ignition873 time (secs) 198 altitude (km) 0.35 Acceleration (g) Second-stage engine cutoff "So 873 minus 349 is 524 second duration of the second stage's first burn.After firing engine stage, it's at 198 altitude and then orbit goes down to 152 kmand the stage fires again and burns for 559 second and shut off at 401 km.The way I looked at it, after the first burn of second stage the spacecraft was in orbit, and oncein orbit, you don't have gravity losses.
5m DCSS burn time is 1125s, not 524 seconds.For LEO mission, practically all of that is needed to reach orbit.
Quote5m DCSS has 3 km/s delta-V for 25t payload (there is no official info how much the new RS68A-version lifts)So it's accelerating from 4.5km/s to 7.5km/s, so in average the velocity will be less than 6km/s (due acceleration being slower when it it more full). 6km/s velocity means gravity loss is about 20% of the gravity loss when stationary.So total gravity loss during the second stage is close to 9.81 * 0.2 * 1125 = 2.2 km/sIt couldn't be.If you assuming second stage has 3 km/sec you saying that 2.2 of that 3 km/sec is gravity loss.
As I said it's mostly the first stage which has most gravity loss. It's possible the entire delta-IV rocket hasaround 2.2 km/sec [or more of gravity loss].
So, entire rocket with all stage gives about 10 km/sec of delta-v. 10 km/sec minus 2.2 km/sec is 7.8 km/sec, which around what is needed to get into orbit.
I would guess stages before second stage starts have a delta-v of about 7 km/sec and have gravity loss of around 2 km/sec, resulting actual velocity of 5 km/sec and second stageadds about 3 km/sec.
I was talking about LEO payloads (25 tons), you are quoting GTO numbers for ~10 ton payloads.When going to LEO, the second stage burns only once, using practically all of it's fuel to reach orbit.So your own numbers just confirms second stage burned for 1083 seconds for that mission, which is quite close to my 1125s number.
A lot of that second stage gravity loss is actually won by the FIRST stage which puts the spacecraft onto "lofted trajectory" so that the rocket does not fall down during the second stage burn, FIRST stage burn quite a lot of extra in vertical dimension to make the rocket stay in the air long enough.
Actually the second stage CANNOT fight it's gravity losses alone, due it's terrible thrust to weight ratio, even if it would start burning vertically from 5 km/s velocity using all of it's energy to fight gravity (loss), it would just fall down. (effective gravity at 5km/s is about 0.33*9.81 m/s^2 = 3.2m/s, 3.2m/s^2 * (25t + 30t) = 176 kN, thrust of DCSS is 110 kN.So the second stage might actually go maybe something like from 4.8 km/s to 7.5 km/s , burning 2.7 km/s horizontally and something like 1.3 m/s vertically(3km/s total by pythagoras), and first stage burning 0.9km/s extra vertically to keep the second stage in air long enough.
The attached image is from an old Boeing chart. Of course the details are superseded by newer information, but what's interesting is the implied conversion (for Delta IV) between payload masses sent to LEO and payload masses sent to Earth-escape (C3=0).
An upgraded Delta IV Heavy with ACES and GEMs could lift 45 tons to LEO, that could probably get a BLEO modified CST-100 on TLI in a single launch.
Quote from: PahTo on 02/19/2014 08:04 pmWait a sec--we should question one of the premises of this thread, placing SRMs on a D-IVH. AIUI, the cores for the D--IV family are all unique, with each of the three cores of the heavy specifically farbicated, and the core for the D-IV M yet another unique core. And it's taken years and effort to reduce the number of unique cores to this point. ...ULA has the SRMs on Delta IV Heavy as a growth option in their literature. It's not just fan-wanked.
Wait a sec--we should question one of the premises of this thread, placing SRMs on a D-IVH. AIUI, the cores for the D--IV family are all unique, with each of the three cores of the heavy specifically farbicated, and the core for the D-IV M yet another unique core. And it's taken years and effort to reduce the number of unique cores to this point. ...
is DIV-H growth just pie in the sky?
That said I love Delta and think there is a way to get a Delta Growth option back into the running. In the medium term it involves consolidating both SLS and Delta on an expendable RS-25E....
Is any of this remotely plausible without direction or funding given to NASA? Would that help, or is DIV-H growth just pie in the sky?
1) We don't need a larger DIV-H to go to the moon, though a larger upper stage could still be useful, and that would give you EELV Phase 1, which is a larger launcher.2) But the launcher isn't the bottleneck, the lack of a lander is.
Quote from: sdsds on 03/09/2014 10:28 pmThat said I love Delta and think there is a way to get a Delta Growth option back into the running. In the medium term it involves consolidating both SLS and Delta on an expendable RS-25E....That reasoning is quite absurd.
From the report p.19:QuoteFor example, the EELV Should Cost Review indicatesprices for the RS-68 engine, the main engine used on Delta IV launchvehicles, are expected to increase four-fold, but is unable to attribute therise in prices to specific and identifiable cost increases. Air Force officialsrequested a cost breakdown on the RS-68 from the same subcontractorwho provided cost data on the RL-10, but the subcontractor has not yetprovided adequate data, according to Air Force officials.Is it known, whether this anticipated price increase happened? By now (Report is from Sep 2011) a RS-68 might be more expensive than a new ssme? What could be reasons for such an increase?
For example, the EELV Should Cost Review indicatesprices for the RS-68 engine, the main engine used on Delta IV launchvehicles, are expected to increase four-fold, but is unable to attribute therise in prices to specific and identifiable cost increases. Air Force officialsrequested a cost breakdown on the RS-68 from the same subcontractorwho provided cost data on the RL-10, but the subcontractor has not yetprovided adequate data, according to Air Force officials.
Re1) Depends on what you mean by "a larger DIV-H" and what you plan to do at the Moon. sdsds pointed out "the implied conversion (for Delta IV) between payload masses sent to LEO and payload masses sent to Earth-escape (C3=0)" but at 26t to 38t w/GEMs to LEO, DeltaIV-H doesn't cut it and needs a new upper.
Re2) I don't consider "the lack of a lander" to be "the bottleneck", but the lack of any agenda or mission that would dictate the lander, staging and supplies.
... I remain profoundly annoyed that this (uprated DIV-H) wasn't even considered for nakedly political reasons.... It was time to talk about what could be done within the next two Presidential terms, not something that was a decade or more away even in the best case scenario.
M129K has put a 45t cap using ACES.
... basing your architecture on the DIV payload system gives you multiple decision-point flexibility. You are not locked into developing either the MHLV (Phase-I), HLV (Phase-II) or SHLV (something like Atlas-V Phase-3B) versions from the outset of the program. You can assess on an on-going basis if you need to upgrade your launchers whilst focussing on payloads and mission development.It's not a panacea by any standards but I have the feeling that NASA would now be a lot closer to fielding Orion and having something useful to do with it if it had gone down this path.
@rusty, ...
I'm also attaching an image of the heavy upgrade option, with 6 SRBs, dual RL-10 upper stage, and a 6.5m diameter fairing. (Anything bigger would require significant pad mods) This version should be able to put 40-45 tons in LEO.