NASA Human Landing System

[Terwin]

On 4/28/2021 at 12:32 PM, YNM said:

I do have one worry however. Funding in a lot of cases, even with partial funding, means that you have the obligation to it. In this case, NASA is only owed half the obligation of what developing Starship for HLS capability is. The rest goes to SpaceX itself, where HLS capability merely represent a subset of what Starship could achieve in their own milestone. My real question is where will they cut the line on calling it "ready for HLS" ? I'm mostly worried by the fact they put out "half or less" - ie. there's chance that they'd be developing something additional and it'll affect HLS deployment even if it's not actually needed in HLS. Now yes flying a vehicle that's closer to perfection is always better - you want every doubts to be down in the mud, if possible - but this could represent one risk that the timescales might slip.

I believe that funding is milestone dependant.

'You successfully demonstrated X, so here is your money'

where X includes things like  'getting your rocket to orbit'. 'demonstrating LEO fuel transfer', 'getting your rocket onto a lunar return trajectory', 'Landing an un-manned rocket on the moon', and 'landing a rocket on the moon with our designated payload and astronauts' 

If they do other things (like 'you landed your booster' or 'you landed your second stage') that would not have a negative impact on funding.

[YNM]

14 minutes ago, Terwin said:

I believe that funding is milestone-dependent.

Ah, right.

Will see I guess how Starship HLS development rolls out.

45 minutes ago, kerbiloid said:

So, is LOP-G  now obsolete?

Not really as ISS partners need somewhere else to settle in. Wouldn't surprise me that if Axiom gets their modules together then it might be more acceptable to either deorbit the ISS or they'd be sold to a private venture completely.

That being said, this is the HLS thread, not the Artemis/Gateway thread.

[Guest]

59 minutes ago, SpaceFace545 said:

not really, NASA just couldn't afford a real solution.

Exactly, SpaceX was the cheapest! 

[SpaceFace545]

38 minutes ago, YNM said:

Not really as ISS partners need somewhere else to settle in. Wouldn't surprise me that if Axiom gets their modules together then it might be more acceptable to either deorbit the ISS or they'd be sold to a private venture completely.

That being said, this is the HLS thread, not the Artemis/Gateway thread.

I'm not sure but I think Axiom is a scam. It's just some art project between two graphic designers. 

[YNM]

8 minutes ago, SpaceFace545 said:

It's just some art project between two graphic designers. 

Most large construction started as either a graph and a sketch, or a concept drawing. Even at the end someone has got to draw it before it could be built - building anything without any plans, if anything, is much worse.

In any case, they are in the time to prove themselves now.

 

That being said, this is the HLS thread, not the ISS thread.

Edited April 30, 2021 by YNM

[RCgothic]

NASA suspends work on HLS due to protests by Dynetics and NT until GAO sorts them out.

Don't think this is going to have any bearing on SpaceX's progress though TBH.

 

 

[tater]

Changes nothing. SpaceX will do it regardless.

[sevenperforce]

22 hours ago, tater said:

I wonder if Be-4 can burn hydrogen. It's 2400kN vs 1860kN for RS-25, so even losing thrust, it should still exceed RS-25 capacity. I say this because we know they are cheap (Tory Bruno rocket cost math places them at under $7M each).

Next are the ridiculously overprices SRBs. As long as the thrust is the same, the core should be able to deal with any drop-in replacement. You'd need something akin to NG S1, 6 Be-4 (burning LNG) (a NG S1 is 3.5m longer than a 5 seg SRB)

Answering my own question...

 

[tater]

Be-3U is ~4xRL-10 in thrust, and close I_sp I think (430-something?). Also cheaper.

16 minutes ago, sevenperforce said:

Answering my own question...

I still wonder if Be-4 could be converted to burn hydrogen, and if so, what would the thrust and I_sp be.

[sevenperforce]

20 hours ago, tater said:

Be-3U is ~4xRL-10 in thrust, and close I_sp I think (430-something?). Also cheaper.

The RL-10 has awe-inspiring specific impulse (up to 470 seconds in some designs) and its T/W ratio is not terrible but its thrust is SO low for its nozzle area that it's pretty useless for a second stage.

The Japanese LE-5A and LE-5B are open expander cycle hydrolox and sport 447-452 seconds so I'm not sure why the BE-3U would be as low as 430 seconds.

Expander cycle engines generally are not very powerful for their size. The RD-146D (upper-stage engine for Angara) comes in at 470 seconds as well but it only delivers 67 kN with a 1.9-meter bell diameter. 

20 hours ago, tater said:

I still wonder if Be-4 could be converted to burn hydrogen, and if so, what would the thrust and I_sp be.

I assume it would need a complete turbopump redesign.

[tater]

27 minutes ago, sevenperforce said:

The RL-10 has awe-inspiring specific impulse (up to 470 seconds in some designs) and its T/W ratio is not terrible but its thrust is SO low for its nozzle area that it's pretty useless for a second stage.

Yeah, I know—but it's crazy expensive.

[sevenperforce]

59 minutes ago, tater said:

Yeah, I know—but it's crazy expensive.

I'm not so worried about cost -- if we're paying for something pricey but the performance is good enough then I'm fine with it -- I'm worried about thrust per area and cooling scheme.

How is the EUS even going to handle mounting four RL-10C-3 engines? It has a regeneratively-cooled nozzle AND a fixed radiatively-cooled nozzle extension AND an extensible radiatively-cooled nozzle extension. Like, that's a LOT. If Ares V ran into problems with mounting non-regeneratively-cooled RS-68s too close to each other, how is the EUS going to manage?

The highest-performing RL-10 that could be clustered ad nauseum, with regenerative cooling handling everything, would have been the RL-10A-4-2 without the nozzle extension that flew on Centaur D-5 for the Atlas V, at 446.4 seconds and 97.9  kN in a 1-meter bell.

But if that's the best you can do, why not just bite the bullet and figure out how to air-start an RS-25?

At 2.4 meters, an air-started RS-25 takes up the same area as four clustered RL-10A-4-2 engines but produces 475% as much thrust. It's T/W ratio is almost exactly the same (0.42% higher, actually!!) and it has a 1.32% advantage in specific impulse.

 

[sevenperforce]

Here's a thought (hear me out).......

Space Shuttle external tank with three SSMEs mounted underneath it and a Centaur V on top.

Two Delta CBC strapped onto the sides cross-feeding to two of the three SSMEs.

Alternately, move the core tank bulkhead and use two Pyrios boosters crossfeeding LOX only to two of the three SSMEs.

[tater]

7 minutes ago, sevenperforce said:

But if that's the best you can do, why not just bite the bullet and figure out how to air-start an RS-25?

That's probably at least as much work as reworking Be-4, and "simplified" RS-25s are already $100,000,000 each (neglecting all dev costs). It's reasonable to assume AJR would happily air start them for a few billion, amiright?

The more crazy the redesign the less likely (even as a thought experiment). Swapping the SRBs with NG boosted gets TLI throw to 48. That implies a payload to LEO of ~120t, right?

Looks like Be-3U at 432 for the 4 RL-10s would get 45t to TLI. It's not like the 3t is the difference between a useful mission and not—since we know with Orion on top we need more like 70t.

This is I suppose the wrong thread for SLS alternatives, but in the scope of human lunar ops, the best thing for SLS would be to make it less expensive, AND up the cadence.  Making a huge cargo capacity doesn't matter if it's still too expensive. If you can get 120t to LEO and therefor 48 to the Moon, I assume your 70t to TLI variant at the bottom gets like 175t to LEO?

If stock cargo SS gets ~150t to LEO, it seems like a stripped, expended version can probably get about the same to LEO. Then the payload is a Centaur of some kind (4xRL-10) and you get the same 70t to TLI

 

[kerbiloid]

On 4/30/2021 at 9:38 PM, SpaceFace545 said:

I'm not sure but I think Axiom is a scam. It's just some art project between two graphic designers. 

According to wiki/ru, it consists of 60+ former NASA employees.

Can't declare that, but it looks like NASA wants its protege SpaceX and its daughter Axiom to let NASA be a NASA Corp.

Isn't that some kind of insiding?

Edited May 2, 2021 by kerbiloid

[tater]

19 minutes ago, kerbiloid said:

According to wiki/ru, it consists of 60+ former NASA employees.

He's being a troll. Axiom is actually building new modules for ISS that will fly free eventually. Maybe NASA likes talking to them since one of the former NASA employees is Charlie Bolden (former Administrator of NASA under Obama)?

Thales Alenia Space is building the pressure vessels (which they would not be doing without being paid). Axiom is hardly fly-by-night.

19 minutes ago, kerbiloid said:

Can't declare that, but it looks like NASA wants its protege SpaceX and its daughter Axiom to let NASA be a NASA Corp.

Isn't that some kind of insiding?

Bigelow didn't submit anything I think. The contract to start was only 100-something million (chump change).

 

 

[SpaceFace545]

42 minutes ago, kerbiloid said:

According to wiki/ru, it consists of 60+ former NASA employees.

Can't declare that, but it looks like NASA wants its protege SpaceX and its daughter Axiom to let NASA be a NASA Corp.

Isn't that some kind of insiding?

I’m just kinda freaked out how axiom has zero info about what they do and it’s also another section of nasa being given away to some corporate dude.

[tater]

24 minutes ago, SpaceFace545 said:

I’m just kinda freaked out how axiom has zero info about what they do and it’s also another section of nasa being given away to some corporate dude.

It's a firm, fixed price contract for $140M.

They get paid after they accomplish it. There was a selection process, but no one else entered—they still would have lost without technical merit.

NASA doesn't build anything. They hire "corporate dudes" to do it for them. They might solicit designs, then pick one. They might build an entire mission around parts from different contractors—North American Aviation, Grumman Aircraft Company, Lockheed Propulsion Company, Boeing, Douglas Aircraft Company, Rocketdyne, etc. (that was just Apollo).

The only difference recently are the existence of firm, fixed price contracts, and a specific requirement that the companies have some plan for commercial use. NASA sees itself in this area as encouraging a space economy that can later make their own exploration goals less expensive, and more achievable. COTS did this, Commercial Crew did this, and the HLS selection is doing this. They want industry to fly on their own dime.

 

[tater]

 

[tater]

Not sure what this does for the HLS losers.

National Team's HLS proposal was for a 2 person flags and footprints mission, and completely ignore "sustainability," and said they'd design a bigger lander for that. Which they have to design  At some point. Not sure what it gets launched with, and not sure how they can make it substantially less expensive than a smaller lander for $6B (if they could have made a bigger one for less, maybe that should have been the first bid?).

Dynetics? This seems like the ideal role for their concept... if it could actually land (making a new crater doesn't count). maybe they could hack the crew compartment back to be a taxi, no excess capacity or space, since the crew would exist, and then climb aboard a lunar Starship left as the habitat?

[Spaceman.Spiff]

On 5/1/2021 at 5:16 PM, sevenperforce said:

The RL-10 has awe-inspiring specific impulse (up to 470 seconds in some designs) and its T/W ratio is not terrible but its thrust is SO low for its nozzle area that it's pretty useless for a second stage.

What about Centaur?

[sevenperforce]

2 hours ago, Spaceman.Spiff said:

What about Centaur?

Centaur SEC uses an RL-10 as well, the RL-10A-4-2. At 451 s it's actually got a poorer specific impulse than the RS-25. Its advantage is its extremely low mass -- just 168 kg -- which is just barely over half the specific impulse mass of the RL10C-2-1 on the Delta IV's upper stage. That, combined with Centaur's extraordinarily lightweight tank design, makes Centaur's mass fraction excellent and makes it extremely good for high-energy orbits. 

But like all other RL-10s it has very low thrust for its nozzle area. Basically, it takes up too much space. TLI is not terribly high energy; you need good thrust for your final push to orbit or you burn too much of your propellant in a lofted trajectory. That's why the J-2X would have made such a good Earth Departure Stage engine despite its lower specific impulse (448 seconds).

Edited May 3, 2021 by sevenperforce
that was dumb

[tater]

5 minutes ago, sevenperforce said:

But like all other RL-10s it has very low thrust for its nozzle area. Basically, it takes up too much space. TLI is not terribly high energy; you need good thrust for your final push to orbit or you burn too much of your propellant in a lofted trajectory. That's why the J-2X would have made such a good Earth Departure Stage engine despite its lower specific impulse (448 seconds).

For crew missions they really should not be stuck with the awful series of Oberth burns ICPS is forced to do. 2 ICPS (RL-10) burns, then another small burn with the OMS engine on Orion.

[Spaceman.Spiff]

14 minutes ago, sevenperforce said:

Centaur SEC uses an RL-10 as well, the RL-10A-4-2. At 451 s it's actually got a poorer specific impulse than the RS-25. Its advantage is its extremely low mass -- just 168 kg -- which is just barely over half the specific impulse of the RL10C-2-1 on the Delta IV's upper stage. That, combined with Centaur's extraordinarily lightweight tank design, makes Centaur's mass fraction excellent and makes it extremely good for high-energy orbits. 

But like all other RL-10s it has very low thrust for its nozzle area. Basically, it takes up too much space. TLI is not terribly high energy; you need good thrust for your final push to orbit or you burn too much of your propellant in a lofted trajectory. That's why the J-2X would have made such a good Earth Departure Stage engine despite its lower specific impulse (448 seconds).

Thank you for explaining. 

[sevenperforce]

1 hour ago, Spaceman.Spiff said:

Thank you for explaining. 

I said specific impulse above when I meant to say mass but otherwise it was a decent explanation