Author Topic: Cargo BFS with Dragon crew.  (Read 10542 times)

Offline KelvinZero

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Cargo BFS with Dragon crew.
« on: 09/30/2017 09:29 AM »
I have twice been tempted to post this throwaway idea, on two different threads.
It could solve two popular issues:

LAS is a popular topic, though it has been established it is not part of the crewed BFS. (and was fairly clear long before the recent presentation)

I really like the idea of five 20-person escapable capsules, one on each tanker flight.

Will NASA let that monster near the ISS anyway? One solution is to dock with a Dragon 2 that is already certified.

While the bit with the ISS isn't exactly Mars-centric, it now leads me to wonder how they'll handle airlocks and docking.

They don't need airlocks. But docking the BFR with the ISS is going to put a lot of mechanical stress on the IDS.

The bigger issue is getting NASA to certify BFR for ISS operations, and SpaceX implementing any changes, before ISS is retired. I don't see that ever happening.

Im thinking along the lines of a special option for the cargo variant, just as the legs were optional on F9R, that lets you include a Dragon 2. The Dragon 2 should be both a LAS and also be able to leave and redock with the Cargo BFS.

I like the absurd levels of redundant safety this allows. You would have a choice of two heat shields. You have two landing rockets on the BFS, plus the SuperDracos&parachute, or if a fault is discovered in orbit, the option of landing via Dragon alone, Parachute with backup of SuperDracos.

This would make the Cargo BFS everything the Shuttle was meant to be and more. 7 crew is plenty for most missions.

Im unsure of a convenient configuration though. I think probably the Dragon would be entirely within the fairing, which opens like jaws. For LAS you would perhaps need some explosive way of removing the fairing? Anyone got better ideas?

Offline su27k

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Re: Cargo BFS with Dragon crew.
« Reply #1 on: 09/30/2017 11:55 AM »
I don't see a way to do this, is there ever a LAS design that involves blowing away the fairing?

Offline Nibb31

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Re: Cargo BFS with Dragon crew.
« Reply #2 on: 09/30/2017 12:02 PM »
I don't see a way to do this, is there ever a LAS design that involves blowing away the fairing?

Soyuz. Also Apollo and Orion.

Offline nacnud

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Re: Cargo BFS with Dragon crew.
« Reply #3 on: 09/30/2017 12:05 PM »
I think Vostok and Gemini used ejection seats that blew away a cover which you might refer to as a fairing.

Offline tonya

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Re: Cargo BFS with Dragon crew.
« Reply #4 on: 09/30/2017 12:15 PM »
For a time, the first shuttle test flights were planned to carry an Apollo capsule in the payload bay. Not for launch abort, but for return in the event the vehicle had to be abandoned in orbit.

I think the Dragon will still be with us for sometime. NASA may approve BFS for use at the ISS, but I think it will be SpaceX who object when they ask them to leave it there for six months at a time! I can't see risk averse NASA relaxing its lifeboat provision.

Online douglas100

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Re: Cargo BFS with Dragon crew.
« Reply #5 on: 09/30/2017 12:35 PM »
I think Vostok and Gemini used ejection seats that blew away a cover which you might refer to as a fairing.

On Gemini there was no fairing of course. The hatches were opened/jettisoned (can't remember which) and the crew ejected. On Vostok there was an actual fairing which wasn't jettisoned. There was a cut out on the side of the fairing which allowed the capsule hatch to be jettisoned followed by ejection.
Douglas Clark

Offline guckyfan

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Re: Cargo BFS with Dragon crew.
« Reply #6 on: 09/30/2017 01:17 PM »
If they do it I see them putting Dragon on the nose of a cargo or tanker BFS. So outside the cargo pod and free to use its abort engines.

Online douglas100

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Re: Cargo BFS with Dragon crew.
« Reply #7 on: 09/30/2017 01:22 PM »
Yeah, makes more sense. Whether such a thing would be tried depends on lots of unknowns, the main ones being how long ISS will be maintained and how long it will take to get BFS operational.
Douglas Clark

Offline KelvinZero

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Re: Cargo BFS with Dragon crew.
« Reply #8 on: 09/30/2017 10:40 PM »
If they do it I see them putting Dragon on the nose of a cargo or tanker BFS. So outside the cargo pod and free to use its abort engines.
You mean on top, outside the frame of the BFS, just like it sits on top of the F9 ? I think this is the simplest to implement but then I think you would HAVE to separate the dragon 2 to land. So you wouldn't get the double redundancy. (Double redundancy is cool because it changes LOC from hopefully much better than 1:100 to something hopefully better than 1:10,000)

How about we extensively modify just the door of the Cargo BFS? The goal being that the Dragon 2 is still outside of the BFS, but usually returns to earth protected by the BFS heat shield. (Of course the door cannot support the mass of the Dragon, there must be some unspecified way to distribute the weight of the Dragon on the door to the rest of the vehicle, not just the door hinges)

This isn't purely for ISS. In the short term Cargo probably has the most uses. Then there are a subset of cases where some crew are useful, ie shuttle-like missions.

The Crew BFS I think only becomes useful a fair bit later when you have more confidence: Moon, where your small crew need more room, LEO Tourism and Mars, where the goal is 50-100 people crammed in like sardines. This approach lets you delay the Crew version while also providing huge safety while the BFS is young.

Offline Ludus

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Re: Cargo BFS with Dragon crew.
« Reply #9 on: 10/01/2017 02:35 AM »
So far, it seems to me like the Tanker is the same as the Cargo version and thereís very little practical reason for a long time for SpaceX to build anything but this single type of simpler ship. For Mars or the Moon human transport put a hab in the cargo hold. This has the major advantage that it lets you leave the hab where itís more useful while returning the ship. Your idea of finding a way to carry a Dragon2 for passenger launches fits with this. Iím assuming just the Dragon2 not the Trunk.

If you reoriented the couches? you could mount the Dragon2 in the hold sideways, pointed out the hatch. In an abort the hatch blows off and the D2 fires itís super Dracoís. In an approach to the ISS the hatch opens normally and itís slowly pushed out and uses its Dracoís to dock. Thereís no exterior mod to the BFR, just D2 mounting hardware wherever most appropriate in the hold. D2 can operate like an emergency abort pod or do normal docking with ISS. It just canít operate in orbit on its own for long without the trunk.
« Last Edit: 10/01/2017 02:43 AM by Ludus »

Online envy887

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Re: Cargo BFS with Dragon crew.
« Reply #10 on: 10/01/2017 02:47 AM »
So far, it seems to me like the Tanker is the same as the Cargo version and thereís very little practical reason for a long time for SpaceX to build anything but this single type of simpler ship. For Mars or the Moon human transport put a hab in the cargo hold. This has the major advantage that it lets you leave the hab where itís more useful while returning the ship. Your idea of finding a way to carry a Dragon2 for passenger launches fits with this. Iím assuming just the Dragon2 not the Trunk.

If you reoriented the couches? you could mount the Dragon2 in the hold sideways, pointed out the hatch. In an abort the hatch blows off and the D2 fires itís super Dracoís. In an approach to the ISS the hatch opens normally and itís slowly pushed out and uses its Dracoís to dock. Thereís no exterior mod to the BFR, just D2 mounting hardware wherever most appropriate in the hold. D2 can operate like an emergency abort pod or do normal docking with ISS. It just canít operate in orbit on its own for long without the trunk.

Dragon 2 can't do an atmospheric abort without the trunk, it needs it for stabilization. I don't know about flying D2 in the cargo bay... It just seems really likely to hit something during an abort.

Offline KelvinZero

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Re: Cargo BFS with Dragon crew.
« Reply #11 on: 10/01/2017 03:09 AM »
I was wondering about the trunk, (including the possible relevance to abort).

If the dragon is not exposed on lift off and only reenters by itself in emergencies then there are some options to move things around a bit that we could speculate on.

Another thing I wanted to add. Many people advocate that a problem with space is that we do not accept enough risk. There may be some truth here, but I also think that "absurd safety" can be transformative. With enough flights, the BFR may become the 747 of space, but we don't have markets or destinations for 100s of people yet. The dragon-variant might leapfrog us to 747-safety while being sufficient for current numbers almost immediately. It could give the population a whole decade more time to get used to space being just as safe as an overseas holiday.


Offline John Alan

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Re: Cargo BFS with Dragon crew.
« Reply #12 on: 10/01/2017 03:39 AM »
Early on (2022 - 2030)
The safest solution would be construct a crew transfer space station in orbit...
Once built and in use...
A crew type yet unmanned BFcrew launches first to the transfer station... side docks via the hatch...
A Dragon 2 with it's F9 S2 still attached (but vented and inert ed) brings up 7 crew safely and in a proven system.
It docks via nose hatch... crew goes aboard station...
A station robot arm grapples the D2/S2 assy and swings it over into an empty BFpacman cargo equipped to secure and haul it back down in one piece...
It then returns the D2/S2 set cleanly and nearly ready to be put on a used F9 S1 and relaunched...
Repeat till BFCrew is manned to required staffing...

I think a pair of D2/S2's will fit side by side in a BFpacman cargo...  not 100% sure on that...

Just saying... NASA or anyone would have a hard time saying no to this idea for early crew missions...  ;)
Once BFR system has demonstrated it to be safe and reliable... repurpose the transfer station
« Last Edit: 10/01/2017 04:01 AM by John Alan »

Offline Norm38

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Re: Cargo BFS with Dragon crew.
« Reply #13 on: 10/01/2017 03:47 AM »
If they do it I see them putting Dragon on the nose of a cargo or tanker BFS. So outside the cargo pod and free to use its abort engines.

If Dragon goes in the nose, how does the BFS renter?  There's a lot of heating and pressure on the nose. Can that structure coexist with Dragon?

Offline biosehnsucht

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Re: Cargo BFS with Dragon crew.
« Reply #14 on: 10/01/2017 05:17 AM »
If you want a crew transfer station, why not the BFS itself? It's pretty much the volume of ISS, in a much more convenient layout. Just fly the Dragon to the BFS and dock directly to it.

I don't think this is likely to happen though, I think Elon is going to push for just launching on BFS (after some unmanned testing of course).
« Last Edit: 10/01/2017 05:18 AM by biosehnsucht »

Offline John Alan

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Re: Cargo BFS with Dragon crew.
« Reply #15 on: 10/01/2017 05:35 AM »
Early on (2022 - 2030)
The safest solution would be construct a crew transfer space station in orbit...
Once built and in use...
A crew type yet unmanned BFcrew launches first to the transfer station... side docks via the hatch...
A Dragon 2 with it's F9 S2 still attached (but vented and inert ed) brings up 7 crew safely and in a proven system.
It docks via nose hatch... crew goes aboard station...
A station robot arm grapples the D2/S2 assy and swings it over into an empty BFpacman cargo equipped to secure and haul it back down in one piece...
It then returns the D2/S2 set cleanly and nearly ready to be put on a used F9 S1 and relaunched...
Repeat till BFCrew is manned to required staffing...

I think a pair of D2/S2's will fit side by side in a BFpacman cargo...  not 100% sure on that...

Just saying... NASA or anyone would have a hard time saying no to this idea for early crew missions...  ;)
Once BFR system has demonstrated it to be safe and reliable... repurpose the transfer station
If you want a crew transfer station, why not the BFS itself? It's pretty much the volume of ISS, in a much more convenient layout. Just fly the Dragon to the BFS and dock directly to it.

I don't think this is likely to happen though, I think Elon is going to push for just launching on BFS (after some unmanned testing of course).

I agree that Elon will push to launch Crew on BFR with no Launch abort system as shown...
And yes they could send a Dragon 2 straight to a BFcrew and offload...

But that will cost you a F9 stage 2... a trunk... (both burned up in the atmosphere)
...and you get a toasted and salt water dipped Dragon 2 back...

With what I outlined above...
You turn Dragon Crew as approved into a fully reusable system with quick turn around times...
And you only use it until everyone gets happy with BFS flying with no Launch abort system...

It was just an idea...  ;)
« Last Edit: 10/01/2017 05:38 AM by John Alan »

Offline su27k

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Re: Cargo BFS with Dragon crew.
« Reply #16 on: 10/01/2017 05:48 AM »
If they do it I see them putting Dragon on the nose of a cargo or tanker BFS. So outside the cargo pod and free to use its abort engines.

If Dragon goes in the nose, how does the BFS renter?  There's a lot of heating and pressure on the nose. Can that structure coexist with Dragon?

Dragon will need to leave BFS and re-enter by itself, the structure (adapter) will probably need to be jettisoned before BFS re-enter. So this idea is basically just using BFR as replacement for F9, the downside is they'll need to build a super high crew access tower for this, and they'll still need to refurbish Dragon.

Offline KelvinZero

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Re: Cargo BFS with Dragon crew.
« Reply #17 on: 10/01/2017 06:10 AM »
Just a reminder, What I really wanted to talk about in the OP was a Cargo BFS + Dragon 2 where

*The Dragon serves as a LAS at every point, up, down and in LEO (hopefully making 1:100~1:1000 odds of LOC into 1:10,000~1:1000,000) - so it has to be able to return inside (or at least protected by) the Cargo BFS.

*The dragon can leave the Cargo BFR and return to it while in LEO, removing any ISS issues but possibly having a bunch of other uses also.
« Last Edit: 10/01/2017 06:13 AM by KelvinZero »

Offline Nibb31

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Re: Cargo BFS with Dragon crew.
« Reply #18 on: 10/01/2017 06:17 AM »
Just a reminder, What I really wanted to talk about in the OP was a Cargo BFS + Dragon 2 where

*The Dragon serves as a LAS at every point, up, down and in LEO (hopefully making 1:100~1:1000 odds of LOC into 1:10,000~1:1000,000) - so it has to be able to return inside (or at least protected by) the Cargo BFS.

*The dragon can leave the Cargo BFR and return to it while in LEO, removing any ISS issues but possibly having a bunch of other uses also.

Your solution doesn't solve any problems.
* BFS is supposed to be reliable enough to not need a LAS.
* If BFS is carrying NASA astronauts and cargo, then NASA will want to certify it.
* There will be very little overlap, if any, between ISS and BFS, so there is no point in engineering an expensive solution for one or two flights.

Offline KelvinZero

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Re: Cargo BFS with Dragon crew.
« Reply #19 on: 10/01/2017 06:48 AM »
* It gives you a 100x safety improvement while you are working up the confidence in your vehicle.. and NASA may point blank refuse a vehicle without a LAS for a good long time.
* Surely NASA is not so bureaucratic that they cannot separate launching and docking risks.
* Probably true, but the same issue may apply to the next station we have not seen yet.

Another advantage of this is that you can start with just one variant, the Cargo variant. This also happens to be the most immediately useful and a lot cheaper than the Crew variant.

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