Author Topic: Storable Propellant Earth Departure Stages  (Read 71433 times)

Offline QuantumG

  • Senior Member
  • *****
  • Posts: 9238
  • Australia
  • Liked: 4477
  • Likes Given: 1108
Storable Propellant Earth Departure Stages
« on: 08/29/2013 01:49 am »
According to this article, which has it's own thread, NASA wants a 43 ton lunar lander.. for some reason.. and they say the only way to get a payload that big into lunar orbit is with the SLS.

I don't get it. What's wrong with just using a storable propellant Earth departure stage? Let's be conservative and say it only has an isp of about 312s, and a propellant mass fraction of 90%, how big would it be?

According to my math, please check me, I figure it would be about 10,458 kg dry and 104,579 kg when full. This would provide the 3107 m/s of delta-v to get through TLI, with the lunar insertion to be done by the lander (as in the NASA architecture).

I know 105 tons sounds like a lot, but it's only two Falcon Heavy launches, and because we're using storable propellant there's no time pressure. If you really wanted to you could do it with Falcon 9 v1.1.


   

« Last Edit: 08/29/2013 01:52 am by QuantumG »
Human spaceflight is basically just LARPing now.

Offline Warren Platts

Re: Storable Propellant Earth Departure Stages
« Reply #1 on: 08/29/2013 02:39 am »
It only has an isp of about 312 s?
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline QuantumG

  • Senior Member
  • *****
  • Posts: 9238
  • Australia
  • Liked: 4477
  • Likes Given: 1108
Re: Storable Propellant Earth Departure Stages
« Reply #2 on: 08/29/2013 02:54 am »
It only has an isp of about 312 s?

For the sake of argument.

Human spaceflight is basically just LARPing now.

Offline RocketmanUS

  • Senior Member
  • *****
  • Posts: 2226
  • USA
  • Liked: 71
  • Likes Given: 31
Re: Storable Propellant Earth Departure Stages
« Reply #3 on: 08/29/2013 03:16 am »
That could work.
First FH launches EDS part filled.
Second FH launches tanker to complete filling of EDS.
Need to figure out the mass of the tanker too.
Also the altitude would be higher than 185 km x 185 km so less mass to that higher orbit.

So if you want to get a 43 mt lander through TLI you would need another tanker launch ( three FH's ). Or use a smaller lander with less payload.

What is the dry mass of the lander?
What is the max payload mass?

I assume it would use a version of the Super Draco.

So a FH would be used to launch the 43 mt lander into LEO.
Would the FH 2nd stage have enough performance to get the lander to the needed altitude and dock with the EDS? ( FH top expected performance 53 mt and lander is 43 mt assuming it would fit a stander fairing and not need a larger more mass sized fairing. )

For crew, Orion would be launched on FH to meet up with the EDS.

For the lander four FH's are needed. $135M x 4 = $540M
For the Orion three FH's are needed. $135M x 3 = $405M
Possible savings.

Could work for commercial if they had a commercial Lunar capsule.

Offline QuantumG

  • Senior Member
  • *****
  • Posts: 9238
  • Australia
  • Liked: 4477
  • Likes Given: 1108
Re: Storable Propellant Earth Departure Stages
« Reply #4 on: 08/29/2013 03:22 am »
Heck, throw ten Falcon Heavy launches at it if you want, you might start to approach the cost of an SLS launch :)
Human spaceflight is basically just LARPing now.

Offline RocketmanUS

  • Senior Member
  • *****
  • Posts: 2226
  • USA
  • Liked: 71
  • Likes Given: 31
Re: Storable Propellant Earth Departure Stages
« Reply #5 on: 08/29/2013 03:34 am »
And if the lander used storable propellant too, mass was 43 mt and did the LLO insertion burn it would get something around 8 mt?

Forgot to add in the cost of the tankers for the EDS.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25225
  • Likes Given: 12114
Re: Storable Propellant Earth Departure Stages
« Reply #6 on: 08/29/2013 04:04 am »
Put a 40kW electric tug on it (could be built using essentially a modified off-the-shelf commsat bus with a bigger or a couple extra solar arrays and some extra Xenon tanks... big commsats now do about 20kW), and you could put a Apollo-or-larger lander (up to maybe 20mT) in LLO with just an RS-68A Delta IV Heavy. A much bigger one if you used the cheaper Falcon Heavy. It'd take a few years to get all the way there (less if you used a Falcon Heavy and could tolerate a lower Isp, or if you could use a 100kW modified commsat or something it'd take proportionally less time), but so what? A lander in LLO with a single launch of an EELV Heavy. Or a really big lander in LLO with a Falcon Heavy. Have to use storable propellants with the lander, but that's not a huge deal.

Might even be cheaper than developing a hypergolic Earth Departure Stage that is refuelable.

Or heck, if you had a 18mT reusable single-stage hypergolic lander (probably needed to equal the performance of a 14mT two-stager), you launch a big tank of hypergolic propellant on a single Falcon Heavy along with a 100kW modified-commsat-tug, and you could refuel like 3 times per Falcon Heavy launch (alternately, between 6 and 9 refuelings per SLS launch, depending on which version of SLS... but you'd need a bigger tug or you'd need to launch multiple tankers per flight...).

A yet more efficient architecture would use a hydrolox un-crasher stage and a near-zero-boiloff depot fed by fully reusable tugs and a future fully reusable launch vehicle like the envisioned F9R with reusable upper stage.
« Last Edit: 08/29/2013 04:19 am by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline kkattula

  • Member
  • Senior Member
  • *****
  • Posts: 3008
  • Melbourne, Australia
  • Liked: 656
  • Likes Given: 116
Re: Storable Propellant Earth Departure Stages
« Reply #7 on: 08/29/2013 04:18 am »
Why bother with refueling and a tanker?  Just use 2 x FH-payload-sized storable EDS.

One starts the TLI then stages, and the other completes it. With a smaller lander, the second EDS could also do LOI.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25225
  • Likes Given: 12114
Re: Storable Propellant Earth Departure Stages
« Reply #8 on: 08/29/2013 04:28 am »
Continuing my idea of an architecture based off of SEP tug delivery of hypergolic propellant and reusable F9R, reusable single-stage lander in LLO:

If you had a version of Dragon which was refuelable and had at least 800m/s delta-v, you could launch to EML1/2, refuel with a tanker there, then fly to LLO, and take a lander to the surface and back, refuel both lander and Dragon, fly Dragon back to EML1/2 to refuel and then finally back to Earth... could be totally reusable, assuming you could give a capsule enough propellant to do 800m/s... The fueled lander with its huge delta-v capability could be a sort of dispatchable lifeboat if the Dragon got stranded.

...Um, that sounds too complex. Makes more sense to just leave the Dragon or whatever at EML1/2 and take the lander to get between EML1/2 and LLO and back, with refueling at LLO (and EML1/2, though that's not strictly required, it'd be more efficient).

Anyway, MY POINT IS: If you're just sending a lander (without crew) to lunar-orbit rendezvous and aren't in a huge hurry, makes more sense to send it via slow-boat SEP, now that the technology is mature. A single launch of DIVH or especially a Falcon Heavy should be enough to put at very least an Apollo-sized lander in LLO if you leverage electric propulsion as a sort of uber-EDS. Xenon (and Argon, for that matter) is, after all, storable.
« Last Edit: 08/29/2013 04:29 am by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline RocketmanUS

  • Senior Member
  • *****
  • Posts: 2226
  • USA
  • Liked: 71
  • Likes Given: 31
Re: Storable Propellant Earth Departure Stages
« Reply #9 on: 08/29/2013 04:32 am »
Put a 40kW electric tug on it (could be built using essentially a modified off-the-shelf commsat bus with a bigger or a couple extra solar arrays and some extra Xenon tanks... big commsats now do about 20kW), and you could put a Apollo-or-larger lander (up to maybe 20mT) in LLO with just an RS-68A Delta IV Heavy. A much bigger one if you used the cheaper Falcon Heavy. It'd take a few years to get all the way there (less if you used a Falcon Heavy and could tolerate a lower Isp, or if you could use a 100kW modified commsat or something it'd take proportionally less time), but so what? A lander in LLO with a single launch of an EELV Heavy. Or a really big lander in LLO with a Falcon Heavy. Have to use storable propellants with the lander, but that's not a huge deal.

Might even be cheaper than developing a hypergolic Earth Departure Stage that is refuelable.

Or heck, if you had a 18mT reusable single-stage hypergolic lander (probably needed to equal the performance of a 14mT two-stager), you launch a big tank of hypergolic propellant on a single Falcon Heavy along with a 100kW modified-commsat-tug, and you could refuel like 3 times per Falcon Heavy launch (alternately, between 6 and 9 refuelings per SLS launch, depending on which version of SLS... but you'd need a bigger tug or you'd need to launch multiple tankers per flight...).

A yet more efficient architecture would use a hydrolox un-crasher stage and a near-zero-boiloff depot fed by fully reusable tugs and a future fully reusable launch vehicle like the envisioned F9R with reusable upper stage.
Or check this thread out. Crew or cargo and could start with the cargo version.
http://forum.nasaspaceflight.com/index.php?topic=32669.msg1088701#msg1088701

Offline QuantumG

  • Senior Member
  • *****
  • Posts: 9238
  • Australia
  • Liked: 4477
  • Likes Given: 1108
Re: Storable Propellant Earth Departure Stages
« Reply #10 on: 08/29/2013 04:35 am »
...Um, that sounds too complex.

Exactly. Better is the enemy of good enough. The point is that trivial solutions like a storable propellant earth departure stage is cheaper than SLS.
Human spaceflight is basically just LARPing now.

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 39270
  • Minnesota
  • Liked: 25225
  • Likes Given: 12114
Re: Storable Propellant Earth Departure Stages
« Reply #11 on: 08/29/2013 05:13 am »
...Um, that sounds too complex.

Exactly. Better is the enemy of good enough. The point is that trivial solutions like a storable propellant earth departure stage is cheaper than SLS.

If you do EML1/2 instead, you could do dual-launch Falcon Heavy for the entire mission:
1) FH Dragon to EML1/2
2) FH with a 23mT lunar lander (equivalent in performance to the 15mT Apollo lander, but capable of staging to and from EML1/2), launched using a modified commsat acting as an electric tug (probably would want at least 100kW of power if you launch it a year in advance, though 50kW is fine if you can wait two years).

Just two FH launches, just two dockings (like Apollo), no refueling required, just a modification of an existing platform (the comm-sat) acting as your electric EDS for the lander.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline QuantumG

  • Senior Member
  • *****
  • Posts: 9238
  • Australia
  • Liked: 4477
  • Likes Given: 1108
Re: Storable Propellant Earth Departure Stages
« Reply #12 on: 08/29/2013 05:18 am »
Now you're just cheating.. for whatever reason, the assignment was to put a 43 ton lander into lunar orbit. The SLS advocates claim they have the only system that can do that. It's trivial to show they don't. QED.
Human spaceflight is basically just LARPing now.

Offline Downix

  • Senior Member
  • *****
  • Posts: 7082
  • Liked: 22
  • Likes Given: 1
Re: Storable Propellant Earth Departure Stages
« Reply #13 on: 08/29/2013 05:30 am »
From my calculations you will need 158 metric tons of storable propellant to make this work from LEO.

With the Falcon Heavy, with its on-record payload capability of 53 metric tons, you would need 3 launches *just to get the propellant into position* This is not counting the stage nor lander itself, which brings the total launches to 5 (assuming you launch the stage partially-filled). 5 launches will cost *more* than an SLS launch for the same performance, costing you $540 million vs the SLS at ~$500 million, just for the launch vehicle. The Falcon Heavy would also require the cost of the DUUS-alternative, while the SLS cost would include it.

You are throwing money away with this route.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline QuantumG

  • Senior Member
  • *****
  • Posts: 9238
  • Australia
  • Liked: 4477
  • Likes Given: 1108
Re: Storable Propellant Earth Departure Stages
« Reply #14 on: 08/29/2013 05:39 am »
From my calculations you will need 158 metric tons of storable propellant to make this work from LEO.

Please show your work.. I did.

Quote
5 launches will cost *more* than an SLS launch for the same performance, costing you $540 million vs the SLS at ~$500 million, just for the launch vehicle.

You are throwing money away with this route.

Only in pixie land is that the cost of an SLS launch.
Human spaceflight is basically just LARPing now.

Offline Downix

  • Senior Member
  • *****
  • Posts: 7082
  • Liked: 22
  • Likes Given: 1
Re: Storable Propellant Earth Departure Stages
« Reply #15 on: 08/29/2013 05:51 am »
From my calculations you will need 158 metric tons of storable propellant to make this work from LEO.

Please show your work.. I did.
I checked yours. You neglected the weight of the lander itself. To get your figures, you launched an empty stage (10.4 metric tons) but to calculate out the delta-v needed you need to add the lander weight to that, giving you 53.4 metric tons. Using two different delta-v calculators, 104 gets only ~2,050 delta-v.

To propel the stage dry-mass along with the 43 metric ton lander, you need significantly more propellant.
Quote
Quote
5 launches will cost *more* than an SLS launch for the same performance, costing you $540 million vs the SLS at ~$500 million, just for the launch vehicle.

You are throwing money away with this route.

Only in pixie land is that the cost of an SLS launch.

That's the cost on-record. Sorry to hurt your bash-SLS fest.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline QuantumG

  • Senior Member
  • *****
  • Posts: 9238
  • Australia
  • Liked: 4477
  • Likes Given: 1108
Re: Storable Propellant Earth Departure Stages
« Reply #16 on: 08/29/2013 06:01 am »
I checked yours. You neglected the weight of the lander itself.

No I didn't.

Dry mass: 10458
Payload mass: 43000
Total mass at burnout: 53458
Isp: 312
Delta-v: 3107

Apply the rocket equation, you get: 147579 in LEO.
Subtract the payload, you get: 104579
Subtract the dry mass, you get: 94121

Quote
Quote from: QuantumG
Only in pixie land is that the cost of an SLS launch.


That's the cost on-record.

Perhaps you mean that's the marginal cost that they made up, including none of the development costs, all of which could be avoided by just not building the pointless monster rocket.

Quote
Sorry to hurt your bash-SLS fest.

You didn't, if anything you helped.
« Last Edit: 08/29/2013 06:02 am by QuantumG »
Human spaceflight is basically just LARPing now.

Offline Archibald

  • Senior Member
  • *****
  • Posts: 2611
  • Liked: 499
  • Likes Given: 1096
Re: Storable Propellant Earth Departure Stages
« Reply #17 on: 08/29/2013 06:47 am »
According to this article, which has it's own thread, NASA wants a 43 ton lunar lander.. for some reason.. and they say the only way to get a payload that big into lunar orbit is with the SLS.

I don't get it. What's wrong with just using a storable propellant Earth departure stage? Let's be conservative and say it only has an isp of about 312s, and a propellant mass fraction of 90%, how big would it be?

According to my math, please check me, I figure it would be about 10,458 kg dry and 104,579 kg when full. This would provide the 3107 m/s of delta-v to get through TLI, with the lunar insertion to be done by the lander (as in the NASA architecture).

I know 105 tons sounds like a lot, but it's only two Falcon Heavy launches, and because we're using storable propellant there's no time pressure. If you really wanted to you could do it with Falcon 9 v1.1.


A very good idea, kind of "cheap and dirty" lunar architecture. I see your point - Falcon Heavy is cheap, storable propellants are straightforward technology, they don't boiloff with time. I have no doubts this would work pretty well.
So what's wrong, do you ask ?
Simple...
NASA obsession with LOX/LH2. Never, ever, would they consider something else for the TLI. That paradigm also apply to SSTO, btw. It is a little annoying, because issues with liquid hydrogen have long been obvious...  ::)
« Last Edit: 08/29/2013 06:48 am by Archibald »
Han shot first and Gwynne Shotwell !

Offline RocketmanUS

  • Senior Member
  • *****
  • Posts: 2226
  • USA
  • Liked: 71
  • Likes Given: 31
Re: Storable Propellant Earth Departure Stages
« Reply #18 on: 08/29/2013 06:55 am »
I used this calculator, it must be broken  ;D.
http://www.quantumg.net/rocketeq.html

With storable propellants I got 15,848 kg on the Lunar surface.
That is with the 43 mt lander doing the LLO insertion burn and landing burn.

There was little margin for unused propellants and pressurant gas. A little increase would take care of this. 

According to this article, which has it's own thread, NASA wants a 43 ton lunar lander.. for some reason.. and they say the only way to get a payload that big into lunar orbit is with the SLS.

I don't get it. What's wrong with just using a storable propellant Earth departure stage? Let's be conservative and say it only has an isp of about 312s, and a propellant mass fraction of 90%, how big would it be?

According to my math, please check me, I figure it would be about 10,458 kg dry and 104,579 kg when full. This would provide the 3107 m/s of delta-v to get through TLI, with the lunar insertion to be done by the lander (as in the NASA architecture).

I know 105 tons sounds like a lot, but it's only two Falcon Heavy launches, and because we're using storable propellant there's no time pressure. If you really wanted to you could do it with Falcon 9 v1.1.


A very good idea, kind of "cheap and dirty" lunar architecture. I see your point - Falcon Heavy is cheap, storable propellants are straightforward technology, they don't boiloff with time. I have no doubts this would work pretty well.
So what's wrong, do you ask ?
Simple...
NASA obsession with LOX/LH2. Never, ever, would they consider something else for the TLI. That paradigm also apply to SSTO, btw. It is a little annoying, because issues with liquid hydrogen have long been obvious...  ::)

Reason they would not used such a system is they don't want to go to the moon or any crewed BLEO program. That has been the real reason we have been strung along. They had the option with Atlas V and DIV for Lunar before investing in the HLV.

Offline mmeijeri

  • Senior Member
  • *****
  • Posts: 7772
  • Martijn Meijering
  • NL
  • Liked: 397
  • Likes Given: 822
Re: Storable Propellant Earth Departure Stages
« Reply #19 on: 08/29/2013 09:26 am »
Exactly. Better is the enemy of good enough. The point is that trivial solutions like a storable propellant earth departure stage is cheaper than SLS.

You don't even need a storable departure stage if you launch the crew first and have them await a second launch that brings them their EDS inside the ISS. The lander is going to be the heaviest component, but only if it's fueled. If the lander is launched mostly dry, you can move it all the way to L1/L2 before finally loading it with storable propellant.

I think the simplest near term architecture is as follows:

- Separately launched Centaur / DCSS based EDS edit: or F9US
- Crew staging point at ISS
- Dragon
- Hypergolic horizontal lander that isn't loaded with propellant until it gets to L1/L2

The lander could be reusable, but doesn't have to be. Just a reusable ascent stage with an (obviously expendable) crasher stage would be nice already.

And why bother with refueling? Because given the required amounts of propellant it would create a large and fiercely competitive market for launch services, which could drive down launch prices by an order of magnitude or more over the course of a decade. If that were to happen, fully commercial spaceflight would likely be a reality.
« Last Edit: 08/29/2013 01:28 pm by mmeijeri »
Pro-tip: you don't have to be a jerk if someone doesn't agree with your theories

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0