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#26 2019-06-10 17:39:02

Void
Member
Registered: 2011-12-29
Posts: 3,011

Re: Kbd512's Space BFR variants

Will your permission(s), I will post.  I will leave if that desire is indicated.  I believe your words as true, G.W.  And I would take them as law.  But I do see "Potential" loopholes should it indeed work out just as you say.

You used the phrase "Various Prototypes".  From your instruction, I am inclined to believe that some "Starships" will have to be upgraded per field rugged and ready.  And I expect along the lines of what you have said that there will be penalties to pay as far as shipping achievement potentials.

But, Elon Musk and I presume SpaceX, aspire to "Hope" that the cost of a Starship could eventually be less than that of a Falcon 9.  If that proves true or nearly true, then some liberties are present.

I think it is already expected that freighters will be different than propellant carriers, and I expect that if there are any tourist and LEO type editions they will be different yet again.  And for a Mars bound addition, I think rugged is the best idea.  That means less delivered mass I would guess, just as you have suggested.

We have witnessed that a crippled Falcon 9 can ditch at sea, without the total loss of it's value.

So, while I think that many Starships will have to be prepared to land in rugged and soft terrain, there could be room for a type that specializes in bringing mass up, but is lighter, and must land on a good landing pad or ditch at sea.  I would expect that that one may need to be isolated from danger to populations from a potential crash on land, just as much as airliners are so directed.  This could be particularly true, if indeed a Starship of that sort is less than the cost of a Falcon 9.

So, you would get the benefit of the previously advertised performance, but on occasion you might ditch one at sea, or actually have a crash or a topple if it cannot reach a well made landing site.

For the purpose of this argument, I will suppose the method to reach Mars will be Hohmann Transfer, Aero-Burn, and Hover Slam.  I will exclude any further reference to Ballistic Capture notions.

From previous conversations, I think it makes sense to both of us that to top off the propellants on a Starship it would be preferred to do a complete fill from an LEO depot, rather than repeatedly joining ships to top off the propellant.  If you are doing that, I would think that loading a little more cargo when in orbit is not necessarily a show stopper.  I guess if just a small crew, then you could do "Load and go".  However for passengers, I am going to speculate that a different Starship would dock and transfer passengers after loading, and preliminary check-outs.  But certainly I could be wrong on that.

And then there could be LEO booster options.  Either another Starship nudging the Mars bound Starship to a higher orbit to start from, or perhaps even attaching a few Falcon 9 2nd stage boosters which would be expendable.  Complications of course.

I guess I am just looking for possible options for flexibility, to make the trip to Mars with hardware desired and propellants needed more plausible.

It would be different if the staging point was on the surface of the Earth, but it is to be in LEO, or just possibly in high Earth orbit, or slightly higher Earth orbit.  So, more options are open.

I hope you don't mind me posting like this.

Done.

Last edited by Void (2019-06-10 17:59:06)


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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#27 2019-06-10 19:02:41

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 16,181

Re: Kbd512's Space BFR variants

posted some images in the Starship is go topic...

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#28 2019-06-13 18:08:40

kbd512
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Registered: 2015-01-02
Posts: 2,962

Re: Kbd512's Space BFR variants

A CNT-enhanced TSTO variant of Starship should come in well under 85t.  It would be a special purpose military vehicle intended to launch military satellites or to defend against enemy military satellites.  The first stage would be a reusable solid rocket motor.  The second stage would be a military variant of Starship.  The primary advantages would be the ability to launch faster using smaller quantities of liquid propellants and a small stockpile of solid rocket motors, perhaps a dozen or so, and a very large payload bay capable of accommodating hit-to-kill anti-satellite weapons with larger collision nets that do not require an exercise in satellite origami to deploy.

Secondary capabilities would include orbital rescue missions for retrieval of crippled spacecraft or satellites or space junk.  If a soft dock with the spacecraft for transfer to a small pressurized cabin was not possible, then the payload bay would literally swallow the target and affix the much smaller object in place using a series of CNT webbing / straps / tie-downs threaded through the mouth / nose of the payload bay.  Think of it as an impact-absorbing satellite Venus Fly Trap.  Basically, the cargo bay contains additional hardware to hoover up spacecraft / satellites / space junk using flexible tentacles or grippers, negating the need for specialized capture hardware.  It would look pretty much like the artist's rendition of the cargo variant of Starship, with its giant payload bay, apart from having additional payload capture hardware inside and being constructed of lighter materials.

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#29 2019-06-13 18:48:15

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 16,181

Re: Kbd512's Space BFR variants

I got looking through the old VentureStar is it possible now and Delta IV Heavy and Beyond in which we did start to talk materials and technology to make better ships.

Much depends on the goals and not just the materials, fuels and engines its more about the total plan.

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