Author Topic: SpaceX Dragon XL  (Read 219055 times)

Offline TheRadicalModerate

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Re: SpaceX Dragon XL
« Reply #280 on: 04/01/2020 06:18 am »
Separate topic: Dragon XL (without the pressure vessel, with some body-mounted panels and stretched tanks) would make a good recoverable third stage for Starship.

Would allow Starship to do single-launch fully recoverable launches to direct GSO.

The Dragon XL with the payload on top would stage at GTO out of Starship, do the burn into GSO, separate payload, then go back to GTO (phasing may take time?), and dock with Starship/Chomper and come back to Earth. Full reuse, single-launch direct to GSO. Could probably do escape missions this way, too.

Likewise, this is how Dragon XL could be launched and recovered from Starship for Gateway missions. Those folding solar panels (necessary for independent power on Gateway—body panels aren’t enough) will need to be either foldable or expended.

I think you're massively overestimating the delta-v capabilities of the DXL.  Just to do the GTO-to-GEO portion of the trip, you'd need 1800 m/s of delta-v, and then another 1800 m/s to return to GTO empty.  In contrast, the NASA requirements don't require any more than about 700 m/s, and that's pretty generous.  SpaceX isn't going to size the tankage on the DXL for 3600 m/s mission.

BTW, I did a quick back-of-napkin on what you could do with an Isp=300 system if Starship can take 21 t to GTO, assuming a 3 t dry mass for DXL.  To do GTO-GEO-GTO, your max payload is 5.8 t, and you need 9.6 t of prop. 

In contrast, the same 5.8 t payload with the same 3 t dry mass can go loaded to NRHO (430 m/s) and dispose of itself (270 m/s), for 1.4 t of prop.
But propellant is cheap and few payloads would need more than 5.8 tons direct to GSO. Delta IV Heavy can do 6.75to direct GSO. Also, GTO is really high for Starship as Starship has super high dry mass, so staging earlier might work.

As well as an extended bell for Dracos to improve Isp.

OK, I think you've sorta-kinda convinced me.  I don't think an off-the-shelf DXL does the trick but a DXL-like bus with significantly stretched tankage does fill a nice niche.  See next post for why.

Offline TheRadicalModerate

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Re: SpaceX Dragon XL
« Reply #281 on: 04/01/2020 06:19 am »
A third stage would increase the single-launch versatility, but I think direct GSO is a bad application.  It turns out that every single geosynchronous satellite needs station-keeping engines in order to be geostationary;  all they need is a little more fuel, and they can do their own apogee burn for little extra cost.  Solar-electric propulsion makes this even more attractive.  Commercial companies all understand this.  The fact that the Air Force is still asking for GSO missions is a sign of bureaucratic in inefficiency.

The use of super heavy (exploration class) vehicles for launching light cargo means more ride-sharing.  For payloads needing escape trajectories, that implies they should be designed with a kick motor, so they can be dropped off in GTO with everybody else (e.g. the Nusantara/Beresheet mission).  In fact, we may see payloads being designed to be dropped off mid-way between LEO and GTO, as this boosts the payload capacity to escape orbits substantially.

To be fair, it's not just a little extra prop to get from GTO to GEO; 1800 m/s of delta-v on a big satellite is a lot of extra prop.  There's a good case to be made for a Starship-deployed tug, even if I don't think that DXL--at least as-is--is that tug.  As robotbeat said, maybe you could do an all-trunk stretched version.

As for SEP, it's fine--if you have the time to get on station.  But the reason that the DoD has direct-to-GEO profiles in NSSL now is that sometimes you need stuff to be on station fast, and that simply doesn't happen with SEP.  Satellite operators often feel the same way, because a couple of months of their asset not generating revenue can be pretty ugly in terms of debt service.  It's a tradeoff they'll make if they have to, but if they can use their existing buses and get on-station two months earlier, that's tens of millions more dollars in their pocket.

So there's a compelling case for a for a tug for Starship, especially if it wants to compete for NSSL biz.  Consider that the other option for direct-to-GEO would be to refuel 3-4 times in LEO before doing GTO and then GEO.  A dumb tug with enough prop to get there and back is the fastest way to get on-station.

As I said to robotbeat, I get a pretty small payload (5.8 tonnes) to GEO if you want to recover the tug, which itself has a step mass of 15.2 t.  You could do better with an expendable tug:  it'll handle a payload of 8.4 t.  An FHE will actually take more payload to GEO than Starship will, tug or no tug, but an FHE costs $150M and a Starship without any refueling will likely start at about a third of that, and then get even cheaper over time.  But the mission complexity with refueling is too high for the Space Force (still weird to type that) to risk the kinds of assets that they'd likely want to put in GEO.  The same argument applies for a bunch of GEO commsat operators.  The tug is a nice, simple solution.

Offline Twark_Main

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Re: SpaceX Dragon XL
« Reply #282 on: 04/01/2020 08:42 am »
... So the requirement for the DXL is that it be able to generate at least 430 m/s of delta-v when fully loaded, plus another couple of hundred m/s for disposal.  (No clue on what they'll do there; I'm betting on a graveyard orbit of some kind.)  Call it 700 m/s of delta-v total. ...

... Solar orbits are fine for disposal. If we have to start recollecting them for some reason, we will also have to collect trillions of asteroids.

Woods170 (who has sources inside SpaceX) has already confirmed that DXL will be disposed of by reentering in Earth's atmosphere. https://forum.nasaspaceflight.com/index.php?topic=50467.msg2062786#msg2062786
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Offline woods170

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Re: SpaceX Dragon XL
« Reply #283 on: 04/01/2020 09:04 am »
... So the requirement for the DXL is that it be able to generate at least 430 m/s of delta-v when fully loaded, plus another couple of hundred m/s for disposal.  (No clue on what they'll do there; I'm betting on a graveyard orbit of some kind.)  Call it 700 m/s of delta-v total. ...

... Solar orbits are fine for disposal. If we have to start recollecting them for some reason, we will also have to collect trillions of asteroids.

Woods170 (who has sources inside SpaceX) has already confirmed that DXL will be disposed of by reentering in Earth's atmosphere. https://forum.nasaspaceflight.com/index.php?topic=50467.msg2062786#msg2062786

That is indeed an option seriously considered by SpaceX. However, I should point out that disposal into Earth's atmosphere (via destructive reentry) is not explicitly required by NASA.
The NASA requirements in the RPF say this:

Quote from: Attachment_03,_GLS-RQMT-001_Gateway_Logistics_Services_Requirements
L3-GLS-1008 Disposal Transportation

The Logistics services provider shall transport the Logistics Module to a governmentapproved safe and stable end-of-mission disposal orbit or other government-approved disposal location.

Rationale: Because multiple delivery missions are required for assembly and to support crew missions, the Logistics Module needs to be separated and disposed of before the Gateway end of life and disposal. Disposal orbit must comply with the NASA requirements for minimizing orbital debris around the moon and in the vicinity of Earth-moon Lagrange Points. If a Logistics Module will have a secondary mission, beyond the scope of the Logistics Module mission (for NASA or for commercial purposes) the contractor and NASA will determine the approved orbital disposal location that will effectively complete the Logistics Module mission.

So, that is ambiguous. Dragon XL could be sent into solar orbit for disposal. It also could be sent on an intercept orbit to Earth. Or even into an intercept orbit to the Moon.

But, there have been discussions at SpaceX that impacting multiple trash-filled Dragon XL vehicles all over the lunar surface - and thus spreading human trash over the lunar surface in multiple locations - would be a repeat of the mistakes made by mankind on Earth. It also would not fit with the concept of sustainable waste management. Which is why disposal into Earth's atmosphere, via destructive reenty in which both the vehicle and the trash will fully burn up, is considered.


However, I personally think that in the end disposal will take place primarily by sending Dragon XL into solar orbit.
« Last Edit: 04/01/2020 09:17 am by woods170 »

Offline whitelancer64

Re: SpaceX Dragon XL
« Reply #284 on: 04/01/2020 02:58 pm »
... So the requirement for the DXL is that it be able to generate at least 430 m/s of delta-v when fully loaded, plus another couple of hundred m/s for disposal.  (No clue on what they'll do there; I'm betting on a graveyard orbit of some kind.)  Call it 700 m/s of delta-v total. ...

... Solar orbits are fine for disposal. If we have to start recollecting them for some reason, we will also have to collect trillions of asteroids.

Woods170 (who has sources inside SpaceX) has already confirmed that DXL will be disposed of by reentering in Earth's atmosphere. https://forum.nasaspaceflight.com/index.php?topic=50467.msg2062786#msg2062786

That is indeed an option seriously considered by SpaceX. However, I should point out that disposal into Earth's atmosphere (via destructive reentry) is not explicitly required by NASA.
The NASA requirements in the RPF say this:

Quote from: Attachment_03,_GLS-RQMT-001_Gateway_Logistics_Services_Requirements
L3-GLS-1008 Disposal Transportation

The Logistics services provider shall transport the Logistics Module to a governmentapproved safe and stable end-of-mission disposal orbit or other government-approved disposal location.

Rationale: Because multiple delivery missions are required for assembly and to support crew missions, the Logistics Module needs to be separated and disposed of before the Gateway end of life and disposal. Disposal orbit must comply with the NASA requirements for minimizing orbital debris around the moon and in the vicinity of Earth-moon Lagrange Points. If a Logistics Module will have a secondary mission, beyond the scope of the Logistics Module mission (for NASA or for commercial purposes) the contractor and NASA will determine the approved orbital disposal location that will effectively complete the Logistics Module mission.

So, that is ambiguous. Dragon XL could be sent into solar orbit for disposal. It also could be sent on an intercept orbit to Earth. Or even into an intercept orbit to the Moon.

But, there have been discussions at SpaceX that impacting multiple trash-filled Dragon XL vehicles all over the lunar surface - and thus spreading human trash over the lunar surface in multiple locations - would be a repeat of the mistakes made by mankind on Earth. It also would not fit with the concept of sustainable waste management. Which is why disposal into Earth's atmosphere, via destructive reenty in which both the vehicle and the trash will fully burn up, is considered.


However, I personally think that in the end disposal will take place primarily by sending Dragon XL into solar orbit.

Quote
"or other government-approved disposal location."

Makes me think that NASA would designate a specific location for lunar surface impact, not just anywhere randomly on the surface. Probably into the side of a mountain like the GRAIL probes.
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Offline Nathan2go

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Re: SpaceX Dragon XL
« Reply #285 on: 04/02/2020 05:10 am »
...
So there's a compelling case for a for a tug for Starship, especially if it wants to compete for NSSL biz.  Consider that the other option for direct-to-GEO would be to refuel 3-4 times in LEO before doing GTO and then GEO.  A dumb tug with enough prop to get there and back is the fastest way to get on-station.
Agreed.  Tug, third stage, call it what you wish.

Quote from: TheRadicalModerate
As I said to robotbeat, I get a pretty small payload (5.8 tonnes) to GEO if you want to recover the tug, which itself has a step mass of 15.2 t.  You could do better with an expendable tug:  it'll handle a payload of 8.4 t.  An FHE will actually take more payload to GEO than Starship will, tug or no tug, ...
If Starship with your tug is outperformed by FHE, that just means you've undersized the tug.  In the limiting case, Starship has twice the lift capacity of FHE, therefore Starship with a 3rd stage could be optimized to beat FHE.

For re-usability to be practical, the launch rate must be high, and the value of the thing you're reusing must also be high.  I'd expect a clever producer to be able to make expendable 3rd stages so cheap that you can't afford to make them reusable.  In fact, I think these 3rd stages (a.k.a. apogee motors) for boosting payloads from GTO to GSE will continue to mostly be attached to the satellites.  If the DoD wants them to be separate, then people will build that too (but not because it is the economical choice).

However, I think a better case can be made for re-using something like a lunar ascent stage.  When you put NASA crew inside, things get real expensive quickly.  Not that I think SpaceX should build something like that.  NASA will force them to split the flights with another vendor.  So they might as well let Blue Moon handle the people and small stuff, and use Starship (or an expendable variant) for delivering the heavy stuff.

Offline Asteroza

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Re: SpaceX Dragon XL
« Reply #286 on: 04/02/2020 06:03 am »
For re-usability to be practical, the launch rate must be high, and the value of the thing you're reusing must also be high.  I'd expect a clever producer to be able to make expendable 3rd stages so cheap that you can't afford to make them reusable.  In fact, I think these 3rd stages (a.k.a. apogee motors) for boosting payloads from GTO to GSE will continue to mostly be attached to the satellites.  If the DoD wants them to be separate, then people will build that too (but not because it is the economical choice).

With the recent MEV demo for GEO servicing, an argument can be made that future GEO sats being delivered fast actually would want the 3rd stage to separate, to open up a proper servicing/docking port, rather than expecting a servicing craft to latch to an unseparated dead apogee motor nozzle. Notably here I are conflating OTV/servicing vehicle with third stage and apogee kick motor. Whether that means the initial third stage self disposes into GEO graveyard orbit, or comes back for refueling/next payload pickup as an OTV would be irrelevant to the customer, as they simply want the port to be unoccupied after delivery.

Offline envy887

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Re: SpaceX Dragon XL
« Reply #287 on: 04/02/2020 02:19 pm »
However, I personally think that in the end disposal will take place primarily by sending Dragon XL into solar orbit.

Which is fine.

Sending a single spacecraft to a near-Earth solar orbit is somewhat like taking a single grain of sand, breaking it up into a million pieces, and throwing just a single 1 of those millionths of a grain of sand into the middle of the Pacific. We could probably dispose in solar orbit 100 million times per year for the rest of the life of the solar system without noticeably changing the inner solar system background MMOD flux.

Leaving stuff in lunar orbit is roughly a trillion times more of an issue than solar disposal, because it's 10 billion times smaller than near-Earth heliocentric space and the revisit rates are 100 times higher.

LEO is another 10,000 times smaller than lunar orbit, and revisit rates are again another 100 times higher, so trash there is roughly another million times more dangerous than in lunar orbit and a quadrillion times worse than solar disposal. So we really, really don't want to leave stuff in LEO.

Lunar surface disposal sounds likely to kick off debris into lunar orbit, so in the longer term I think that is not a good idea at all.

Offline jedsmd

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Re: SpaceX Dragon XL
« Reply #288 on: 04/02/2020 04:25 pm »
Some thoughts about late load.  Under the contract it is an optional capability (to me it seems like it actually should be a requirement).

When Dragon XL and Stage 2 are assembled together, S2 blocks the main hatch so that cannot be used.  So possibly a hatch through the side of Dragon's pressure vessel?   Would they also put a hatch through the fairing?  Could they access from the crew arm?

Or since late load is not an actual requirement would they keep things simple and not do it?

Offline abaddon

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Re: SpaceX Dragon XL
« Reply #289 on: 04/02/2020 04:28 pm »
Lunar surface disposal sounds likely to kick off debris into lunar orbit, so in the longer term I think that is not a good idea at all.
Given that the moon is pummeled all the time and has (as far as I know?) nothing in orbit, is this a valid concern?

Offline woods170

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Re: SpaceX Dragon XL
« Reply #290 on: 04/02/2020 07:24 pm »
Some thoughts about late load.  Under the contract it is an optional capability (to me it seems like it actually should be a requirement).

When Dragon XL and Stage 2 are assembled together, S2 blocks the main hatch so that cannot be used.  So possibly a hatch through the side of Dragon's pressure vessel?   Would they also put a hatch through the fairing?  Could they access from the crew arm?

Or since late load is not an actual requirement would they keep things simple and not do it?


Late load, if any (I'll explain later), would be done while F9 is still horizontal. Similar to Dragon 1 late load. Don't need crew acces arm. A simple hatch in the payload fairing is enough. Hatches in payload fairings is very common in the commercial spaceflight industry. No big deal.
However, would probably affect the possibility of recovery for such a mission. But, given that NASA pays top dollar, it is likely that SpaceX would not really be upset about losing a fairing set under such a scenario.

Now back to late load:

Late load exists mainly to load time-sensitive cargo aboard the vehicle. Usually life animals, refrigerated goods or perishable goods.
Given that Dragon XL will take a slow route to Gateway (a default mission takes between 12 to 20 weeks to arrive at Gateway) it is out of the question that life animals or perishable goods will be loaded on board.
So, late load probably not required any time soon. Which explains why it is an optional capability, which is listed under the mission unique requirements.
Those requirements may, at some time, be added to the contract and may require new hardware to be developed or existing hardware to be modified, etc.
As such: don't expect the initial Dragon XL to be capable of late load. Unless NASA changes its mind long before Dragon XL is set to perform its first mission.

Offline TheRadicalModerate

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Re: SpaceX Dragon XL
« Reply #291 on: 04/02/2020 09:09 pm »
Agreed.  Tug, third stage, call it what you wish.

I always think of a stage as something with a real interstage, while a tug is something mounted on a PAF.

Quote
If Starship with your tug is outperformed by FHE, that just means you've undersized the tug.  In the limiting case, Starship has twice the lift capacity of FHE, therefore Starship with a 3rd stage could be optimized to beat FHE.

My methodology was to start with the Starship PUG number of 21 t to GTO, figure a 3 t dry mass tug (which is probably a bit heavy, but not by much), and then figure out how much payload you can get to 1800 m/s with Isp=300 and still have the launch mass just under 21 t.  That came out to 8.4 t for an expendable tug, and 5.8 t for a reusable tug that returns to GTO for retrieval.

This is in no way an argument that an FHE (or FH2R, for that matter) is in general a better platform for direct GEO missions.  However, if you need more than 8.4 t to GEO and if you're not willing to incur refueling risk, FH is probably your platform of choice over Starship.  I can think of exactly one customer that would have those requirements, but it's a pretty important one.

Update:  I didn't try a 100 t MMH/NTO tug from LEO.  Assuming a 5 t dry mass (more tankage!), I get 20.2 t for an expendable tug, but only 1.7 t for a retrievable one.

If you go with methalox inside the fairing, you could do better on both the LEO and GTO variants.  But cyrogenics inside a fairing requires some interesting venting if you don't want things to get kinda explode-y.  You need a genuine third stage (per my definition above) unless you bite off the venting problem, and the architecture doesn't really support that--at least not with a reusable Starship.

Update to the Update:  5 t dry mass is probably too low.  If you're sticking with Dracos or even SuperDracos, your helium tanks are gonna be big, and you likely need more mass than that to deal with the MMH and NTO tanks.  At 9 t dry mass, you get 14.2 t to GEO expendably, and reusable is impossible.
« Last Edit: 04/02/2020 09:26 pm by TheRadicalModerate »

Offline gemmy0I

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Re: SpaceX Dragon XL
« Reply #292 on: 04/02/2020 09:29 pm »
My methodology was to start with the Starship PUG number of 21 t to GTO, figure a 3 t dry mass tug (which is probably a bit heavy, but not by much), and then figure out how much payload you can get to 1800 m/s with Isp=300 and still have the launch mass just under 21 t.  That came out to 8.4 t for an expendable tug, and 5.8 t for a reusable tug that returns to GTO for retrieval.

This is in no way an argument that an FHE (or FH2R, for that matter) is in general a better platform for direct GEO missions.  However, if you need more than 8.4 t to GEO and if you're not willing to incur refueling risk, FH is probably your platform of choice over Starship.  I can think of exactly one customer that would have those requirements, but it's a pretty important one.
Out of curiosity, have you tried running the numbers for staging the tug at a subsynchronous GTO, e.g. >1800 m/s to go?

Starship (and F9/FH too, for that matter - we're seeing recent comsats on F9 optimized for subsynchronous deployments for exactly this reason) is so LEO-optimized that I would imagine you could stage quite a bit lower and come out ahead. Every additional m/s you have to haul Starship's dead weight beyond LEO has to be paid for quite dearly.

I'd be quite curious where the break-even point is (although I imagine the calculation is far from trivial, as the bigger the tug gets, the more complicated its design gets and the more of its own dry mass it incurs), particularly for a reusable tug that returns to the Starship for retrieval.

I would imagine that even if SpaceX itself doesn't feel a strong need to build such a thing (due to the demand for GEO launches decreasing or at least having a ceiling far below the expected demand for other orbits), it would be right up the alley of someone like ULA (e.g. a reusable Centaur riding on Starship - they wouldn't even need ACES for this) to offer as a third-party service if they wanted to capitalize on their strongest assets to stay alive in a post-Starship world.

Edit: Looks like you've addressed a lot of these questions in your edits. :) I'll respond to them separately below.
« Last Edit: 04/02/2020 09:41 pm by gemmy0I »

Offline gemmy0I

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Re: SpaceX Dragon XL
« Reply #293 on: 04/02/2020 09:40 pm »
Update:  I didn't try a 100 t MMH/NTO tug from LEO.  Assuming a 5 t dry mass (more tankage!), I get 20.2 t for an expendable tug, but only 1.7 t for a retrievable one.

If you go with methalox inside the fairing, you could do better on both the LEO and GTO variants.  But cyrogenics inside a fairing requires some interesting venting if you don't want things to get kinda explode-y.  You need a genuine third stage (per my definition above) unless you bite off the venting problem, and the architecture doesn't really support that--at least not with a reusable Starship.

Update to the Update:  5 t dry mass is probably too low.  If you're sticking with Dracos or even SuperDracos, your helium tanks are gonna be big, and you likely need more mass than that to deal with the MMH and NTO tanks.  At 9 t dry mass, you get 14.2 t to GEO expendably, and reusable is impossible.
Interesting. So it sounds like the break-even point is definitely somewhere in between LEO and GTO (at least for a hypergolic tug).

Probably the best sort of tug for staging from LEO would be something like Vigoride's water/plasma-based (or something like that, I'm not familiar with the details) electric propulsion tugs. They can apparently scale up quite well (much better than traditional xenon/krypton ion propulsion) and, IIRC, have better thrust (at the expense of some Isp, which isn't terribly bad since it's still quite high). Venting wouldn't be an issue since the propellant is simple water. It still wouldn't be an especially fast ride to GEO, however.

I do wonder if the hydrolox venting problem is really as hard as it seems. Shouldn't it just be a matter of having a detachable/re-attachable umbilical within the fairing, connecting the tug's vent output to a vent on the leeward fairing clamshell? That shouldn't compromise reusability at all. Enabling the umbilical to re-connect autonomously in space when the tug re-docks with Starship would be the key challenge, but it seems like something that can be solved with some relatively simple robotics. As one of SpaceX's Starship engineers put it during a recent talk, "mass covers a multitude of sins" and Starship has so much mass-to-orbit to spare that a nice (and completely reusable, so per-unit costs aren't a big deal) robotic arm would likely barely make a dent in the end-to-end payload (since it'd only be going to LEO and not staying with the tug).

Offline TheRadicalModerate

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Re: SpaceX Dragon XL
« Reply #294 on: 04/03/2020 12:17 am »
Interesting. So it sounds like the break-even point is definitely somewhere in between LEO and GTO (at least for a hypergolic tug).

Probably the best sort of tug for staging from LEO would be something like Vigoride's water/plasma-based (or something like that, I'm not familiar with the details) electric propulsion tugs. They can apparently scale up quite well (much better than traditional xenon/krypton ion propulsion) and, IIRC, have better thrust (at the expense of some Isp, which isn't terribly bad since it's still quite high). Venting wouldn't be an issue since the propellant is simple water. It still wouldn't be an especially fast ride to GEO, however.

I do wonder if the hydrolox venting problem is really as hard as it seems. Shouldn't it just be a matter of having a detachable/re-attachable umbilical within the fairing, connecting the tug's vent output to a vent on the leeward fairing clamshell? That shouldn't compromise reusability at all. Enabling the umbilical to re-connect autonomously in space when the tug re-docks with Starship would be the key challenge, but it seems like something that can be solved with some relatively simple robotics. As one of SpaceX's Starship engineers put it during a recent talk, "mass covers a multitude of sins" and Starship has so much mass-to-orbit to spare that a nice (and completely reusable, so per-unit costs aren't a big deal) robotic arm would likely barely make a dent in the end-to-end payload (since it'd only be going to LEO and not staying with the tug).

I get 11.8 t to GEO on an FHE, and 10.7 t on an FH2R (I think my model's a little optimistic on reserves for recovery, though).  So a 100 t expendable tug+payload in Starship, even if it only supports a 14 t payload (if I'm more conservative with the dry mass), will handily outperform both of them.

This is really going to come down to how big the market is for extremely heavy payloads that have to be on-station immediately with low risk.  I can't think of anything other than military stuff that fills the bill there, so the decision to build a heavy tug pretty much depends on how far they want to push the envelope.  On the other hand, there's a more diverse market for getting commsats on station quickly, and a fairly modest DXL variant could do that very simply with the 21 t to GTO.  Yeah, there are sub-sync variants, but my guess is that GTO version covers almost all of the market that isn't military.

Hydrolox (and by extension methalox) venting in the fairing has been solved on Atlas V 5xx (where the Centaur is inside the fairing); that's what that weird spigot that sticks out of the fairing.  I guess you could do that on the leeward side of a Starship.  But it's an all-the-way-to-orbit problem, not just a pre-launch one.

Offline omelet1978

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Re: SpaceX Dragon XL
« Reply #295 on: 04/05/2020 02:48 am »
I was just wondering from the various discussions on here if there was an answer as to how Falcon Heavy would get the Dragon XL to the Gateway?

As in fully expendable, center core expended with side boosters recovered, etc...my bet would be the second option with the side boosters potentially doing a sea landing on the drone ships. I know there is lots of talk about the Starship but I'm just wanting Falcon Heavy to be used as much as possible until more powerful rockets come online and are flight proven over time.

Offline Coastal Ron

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Re: SpaceX Dragon XL
« Reply #296 on: 04/05/2020 03:06 am »
I was just wondering from the various discussions on here if there was an answer as to how Falcon Heavy would get the Dragon XL to the Gateway?

All NASA said in their press release was that it was a Falcon Heavy.

Quote
As in fully expendable, center core expended with side boosters recovered, etc...my bet would be the second option with the side boosters potentially doing a sea landing on the drone ships.

I'm sure there are NSF members that can do the math, but SpaceX would not have hesitated to bid a fully expendable Falcon Heavy is that was what was needed.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline russianhalo117

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Re: SpaceX Dragon XL
« Reply #297 on: 04/05/2020 03:09 am »
I was just wondering from the various discussions on here if there was an answer as to how Falcon Heavy would get the Dragon XL to the Gateway?

As in fully expendable, center core expended with side boosters recovered, etc...my bet would be the second option with the side boosters potentially doing a sea landing on the drone ships. I know there is lots of talk about the Starship but I'm just wanting Falcon Heavy to be used as much as possible until more powerful rockets come online and are flight proven over time.
It has yet to be publicly stated by SpaceX or NASA. We only know the PCM's max volumetric cargo mass and lack the PCM and SM dry and wet masses respectively with and without cargo. We also don't have the propulsion info as the only graphic shown was an early render via artistic license.

Offline TheRadicalModerate

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Re: SpaceX Dragon XL
« Reply #298 on: 04/05/2020 07:20 am »
I was just wondering from the various discussions on here if there was an answer as to how Falcon Heavy would get the Dragon XL to the Gateway?

As in fully expendable, center core expended with side boosters recovered, etc...my bet would be the second option with the side boosters potentially doing a sea landing on the drone ships. I know there is lots of talk about the Starship but I'm just wanting Falcon Heavy to be used as much as possible until more powerful rockets come online and are flight proven over time.

I'm about 99% sure that the FH will take the DXL to TLI, and then the DXL will be responsible for inserting itself into NRHO and later disposing of itself.  A DXL with 700 m/s of delta-v is more than adequate.

Whether you need an FH3R, an FH2R, or an FHE to go to TLI will likely be a function of the exact launch mass of the DXL.  I'd guess it will vary mission-by-mission.  I doubt that many of them will be light enough to use an FH3R.
« Last Edit: 04/05/2020 07:21 am by TheRadicalModerate »

Offline MATTBLAK

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Re: SpaceX Dragon XL
« Reply #299 on: 04/05/2020 07:32 am »
Slightly out of left-field question: could a Dragon XL derivative be used as a transfer stage for a 3-stage lunar lander? (Artemis)
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