Do y'all think the Space-X Super heavy/Star ship would work out?

[DDE]

17 minutes ago, Rakaydos said:

At a million dollars per launch and 100 tons of mixed cargo, the transport costs are $10 per kg. That's probably the upper bound of when point to point cargo starts making sense.

An optimistic estimate, and it’s still not enough.

Quote

The demand for air freight is limited by cost, typically priced 4–5 times that of road transport and 12–16 times that of sea transport. Air freight rates generally range from $1.50–$4.50 per kilogram, while the value of air cargo typically exceeds $4.00 per kilogram. Commodities shipped by air thus have high values per unit or are very time-sensitive, such as documents, pharmaceuticals, fashion garments, production samples, electronics consumer goods, and perishable agricultural and seafood products. They also include some inputs to meet just-in-time production and emergency shipments of spare parts.

Demand for air freight exports has been limited from landlocked developing countries because most enterprises ship small volumes of low value goods. The main exports shipped by air from developing countries are cut flowers, electronic parts, and fresh fruits and vegetables. Imports by air typically include high value consumer goods. However, without a significant outbound flow, the inbound air freight rates are higher — reducing the types and quantities of goods transported by air.

http://www.worldbank.org/en/topic/transport/publication/air-freight-study

The later bit showcases another nice aspect: the Grounded Starship would have to seek stable two-way traffic, or face a doubling of the price per kg.

[tater]

P2P cargo is not a thing. In a dream world where they manage P2P human transport, then they might as well take cargo as well, but the regulatory hurdles of P2P make the whole idea pretty kooky, frankly. The offshore idea seems OK until you realize that they will have the same go/no-go criteria as other rockets, and people have things like pleasure boats that will delay flights should they get too close, etc (where too close is defined pretty broadly at this point, it's any craft in a vast area downrange).

[kerbiloid]

3 hours ago, Rakaydos said:

At a million dollars per launch and 100 tons of mixed cargo, the transport costs are $10 per kg. That's probably the upper bound of when point to point cargo starts making sense.

If there are one or two BFR per city, you'll wait for a year in queue to pay $10 because there will be a million more such customers.
Or pay $10 000 to get closer to the queue head.

If there is a hundred BFR, you'll pay $10 for delivery itself and $10 000 more for their parking and environmental taxes.
(Imagine their fuel storage)

P.S.
Btw how much fuel contains BFR if count in railway cysterns?

P.P.S.
Not sure if in US they bring the fuel by railway, though. So, maybe in trucks.

Edited February 8, 2019 by kerbiloid

[tater]

LNG is piped right into people's houses in the US. My house if off the gas lines, so I have a propane tank, but 99%+ of my city has LNG lines into every house. Obviously pure methane is transported in railcars/trucks, but perhaps it's possible to clean LNG at the target, and only haul away "not methane".

[DDE]

4 hours ago, kerbiloid said:

Imagine their fuel storage

Imagine the fuel storage that can cope with the oft-touted scenario of emergency delivery. 

4 hours ago, kerbiloid said:

P.S.
Btw how much fuel contains BFR if count in railway cysterns?

Standard Soviet hydrocarbon tankers would fit 45 m3 or so.

An 8G513 tanker used at Baikonur fits 36 tons of lOx.

Edited February 8, 2019 by DDE

[sevenperforce]

So here's a question. Let's say that the Starship absolutely positively does need an LES.

What's the safest, cleanest, lowest-mass way of doing it?

[DDE]

9 minutes ago, sevenperforce said:

So here's a question. Let's say that the Starship absolutely positively does need an LES.

What's the safest, cleanest, lowest-mass way of doing it?

Define "Starship". The payload section doesn't seem to exist even as a napkin study.

[tater]

6 minutes ago, sevenperforce said:

So here's a question. Let's say that the Starship absolutely positively does need an LES.

What's the safest, cleanest, lowest-mass way of doing it?

First they'd need to decide on a useful crew for it as a test vehicle. I'm not saying Starship as a class needs LES, I'm saying that for early human rating, it would be sensible. A test crew might be 2-8 people? Even if that ended up adding the total loaded mass of a Crew Dragon to the vehicle, it barely scratches the capability since I don't see the crew vehicle as also used for cargo (to space, clearly different if you land it on the Moon, etc).

Whatever that number is determines the size. The vehicle is so overbuilt that the mass doesn't matter much, honestly. I'd make the flight deck at the nose a capsule that can separate in an emergency (same mold line as Starship). Solids are likely the safest, else hypergolics like Dragon 2.

We have to remember that the crew vehicle is built as a sort of "colonial transport" notionally, but in the real world, nothing even close to the theoretical number of passengers will ever be on it (forget P2P for now, think of it as a moon/mars vehicle (the latter even less likely any time soon)). So if it can hold 100 people and 100 tonnes of their cargo, and bring that with refilling to the Moon (and just the people back), then what is the capability with say 6 people, and just a few tonnes of cargo?

[sevenperforce]

19 minutes ago, tater said:

First they'd need to decide on a useful crew for it as a test vehicle. I'm not saying Starship as a class needs LES, I'm saying that for early human rating, it would be sensible. A test crew might be 2-8 people? Even if that ended up adding the total loaded mass of a Crew Dragon to the vehicle, it barely scratches the capability since I don't see the crew vehicle as also used for cargo (to space, clearly different if you land it on the Moon, etc).

Whatever that number is determines the size. The vehicle is so overbuilt that the mass doesn't matter much, honestly. I'd make the flight deck at the nose a capsule that can separate in an emergency (same mold line as Starship). Solids are likely the safest, else hypergolics like Dragon 2.

I don't think we will see a crew of 100 on it any time soon, but LES capacity for up to 20 crew is probably a safe bet. You don't want to be limited to only 7-10 people when you have that kind of mass budget.

Do you embed a Dragon analogue inside the larger cabin and use detcord to shred the Starship's outer mold line in an abort, or do you integrate the escape capsule into the outer mold line? Does the escape pod have an internal heat shield or does the external heat shield have a shear point?  How do you keep the escape vehicle aerodynamically stable during a pad or Max-Q abort? 

One thing learned from Challenger is that a hardened cabin is surprisingly good at keeping crew safe in an RUD as long as it doesn't take a direct breaching hit from a structural member. Kind of hard to rig chutes that would deploy successfully in that kind of situation.

[tater]

Yeah, I remember watching the crew cabin on Challenger tumble down. Once we realized what we were seeing (minutes after it happened, watching the replays, live), we were horrified.

I would keep the same mold line, it would be in effect a stage 3 that never gets used (hopefully). Seems like some sort of pop-out fins (gridfins?) at the back might do the trick.

It would be a PITA, and it would be expensive to test, no question. What's the alternative, though? How many flights would they have to complete successfully before people would consider it safe? At least 130-something?

[sevenperforce]

9 minutes ago, tater said:

Yeah, I remember watching the crew cabin on Challenger tumble down. Once we realized what we were seeing (minutes after it happened, watching the replays, live), we were horrified.

I am kicking around the idea of combining ejection seats with what would in essence be a solid, pressurized roll cage. Titanium or hardened steel with external crumple zones and passive, single-use TPS. Ejection seats for landing mishap or a pad abort; in any other envelope you depend on the armored cabin to protect you from vehicle breakup and then you eject at a safe altitude a la Vostok 1.

9 minutes ago, tater said:

I would keep the same mold line, it would be in effect a stage 3 that never gets used (hopefully). Seems like some sort of pop-out fins (gridfins?) at the back might do the trick.

You run into mold line issues with respect to TPS. The Starship's active heat shield is part of the outer mold line and so cannot easily make the crew capsule a serially-mounted stage.

It would be neat if you could find a way to utilize the upper canards. I don't know, though. Too complex, and you end up with a module that could very well need its own LES.

9 minutes ago, tater said:

It would be a PITA, and it would be expensive to test, no question. What's the alternative, though? How many flights would they have to complete successfully before people would consider it safe? At least 130-something?

Well, 130 is not as many as we might think when flying full-reuse, but I'm thinking seriously about what alternative LES options might be out there.

[tater]

There was a sketch up the thread of a sort of "pop out the top" pod (where the big window is). I suppose something like that is not impossible, it's just that the shape ideally needs to be passively stable, even if used at MaxQ. Seats seem like a non-starter to me, I'd still think pods (b-58). Also there is the problem of direction. If a fighter plane pilot was to eject on the runway, he's ejected up. On BFR, you'd be ejected sideways. No room for chute deployment (for a pad abort situation).

BTW, for full-fledged BFR, Musk explicitly stated that it would have to be airliner level safety or no one would buy a ticket. That seems... impossible to demonstrate.

[sevenperforce]

47 minutes ago, tater said:

There was a sketch up the thread of a sort of "pop out the top" pod (where the big window is). I suppose something like that is not impossible, it's just that the shape ideally needs to be passively stable, even if used at MaxQ. Seats seem like a non-starter to me, I'd still think pods (b-58). Also there is the problem of direction. If a fighter plane pilot was to eject on the runway, he's ejected up. On BFR, you'd be ejected sideways. No room for chute deployment (for a pad abort situation).

The biconic entry is what really makes an escape capsule a challenging thing. In a way, it's the same problem the Shuttle had. Every launch vehicle with capsule LES has had the crew cabin ensconced neatly atop the launch vehicle, with clean separation baked right into the design. You can't do that quite so easily with a biconic-entry vehicle, because you are no longer following an otherwise-nominal separation; rather, you have to cut a plane across the heat shield. The only other option is to have your escape capsule buried inside the outer mold line of the vehicle nose, requiring purposed explosives to shred the vehicle skin in order to achieve clean separation. 

Of course, the former option--putting a seam in the heat shield--is nothing new; the Shuttle and Buran did it neatly with landing gear, as did at least few different capsules that had hatches passing through the shield. It's just not a good option for an actively-cooled heat shield like the one proposed for Starship. You'd need to use detcord to clean-cut circumferentially around the ventral mold line, and then you're dealing with a LOT of excess weight, so you'd be better off going with the "blow the nose to shreds and blast off" approach. 

I wonder if the placement of the forward actuating fins can be adjusted back so that the forward section of the cabin could separate straight up, taking the fins with them to provide passive aerodynamic stability. Locate some head-pressure tanks inside the cabin area (used in nominal missions to pump the mains) and connect them to hot-gas thrusters for separation boost. Then glide to a landing on skids, or something. That's an option that allows ejection on predetermined seam lines without any additional explosives.

Ejection at a diagonal is a possibility, of course. It's just harder from the standpoint of passive aerodynamic stability, and you REALLY have to shred the entire outer skin.

[StrandedonEarth]

11 hours ago, tater said:

LNG is piped right into people's houses in the US. ... 99%+ of my city has LNG lines into every house. 

LNG? Liquified Natural Gas? Around here the natural gas pipes are full of gas, not liquid. Those must be some high-pressure pipes.... 

(just bustin your chops like you busted mine over P2P. I have seen the error of my ways lol)

[tater]

43 minutes ago, StrandedonEarth said:

LNG? Liquified Natural Gas? Around here the natural gas pipes are full of gas, not liquid. Those must be some high-pressure pipes.... 

(just bustin your chops like you busted mine over P2P. I have seen the error of my ways lol)

You are correct. NG, not LNG. Mine is propane, and the tank is indeed filled with liquid (in the tank, not the pipes), so I tend to think of NG as the same.

[kerbiloid]

They are talking about the crew of 20, of 100, etc...
Forcing all my imagination I can't imagine how to use such crowd at one place.

All I can imagine for any base in the foreseeable future, are 8 humans.
2 pilots, 2 engineers, 2 geologists, (so, 2 field squads of 3), 1 moonshiner fuel plant engineer, 1 medic (to issue the medical leaves when somebody is feeling lazy).

Or crew of 6 for an high-orbital military pad (commander-in-chief aka pilot _{of the escape pod}, medic, 4 engineers (3 shifts + 1 backup)).
Ok, + 1 political commissar and + 1 chief of staff, so also 8.

A scientific orbital station unlikely needs more than 8.

And even they should be being replaced by four, to keep the secret stashes and patches known for somebody.

So, imho, a crew of comfortable 4 or cramped 8 is absolutely the top, until they start flying in tesla gliders remotely powered with fusion plant _{(Like we can do right now in KSP).}
So, no sense in a crewed BFS at all, it'd be a pure cargo delivering system.

More sense in a small reusable taxi spaceplane like a Dreamweaver or so.

(Unless they are planning to revive the Project Horizon with infantry squads on the Moon)

Edited February 9, 2019 by kerbiloid

[tater]

51 minutes ago, kerbiloid said:

Forcing all my imagination I can't imagine how to use such crowd at one place.

Yeah, exactly.Nothing for anyone to do.

[Xd the great]

50 minutes ago, kerbiloid said:

They are talking about the crew of 20, of 100, etc...
Forcing all my imagination I can't imagine how to use such crowd at one place.

All I can imagine for any base in the foreseeable future, are 8 humans.
2 pilots, 2 engineers, 2 geologists, (so, 2 field squads of 3), 1 moonshiner fuel plant engineer, 1 medic (to issue the medical leaves when somebody is feeling lazy).

Or crew of 6 for an high-orbital military pad (commander-in-chief aka pilot _{of the escape pod}, medic, 4 engineers (3 shifts + 1 backup)).
Ok, + 1 political commissar and + 1 chief of staff, so also 8.

A scientific orbital station unlikely needs more than 8.

And even they should be being replaced by four, to keep the secret stashes and patches known for somebody.

So, imho, a crew of comfortable 4 or cramped 8 is absolutely the top, until they start flying in tesla gliders remotely powered with fusion plant _{(Like we can do right now in KSP).}
So, no sense in a crewed BFS at all, it'd be a pure cargo delivering system.

More sense in a small reusable taxi spaceplane like a Dreamweaver or so.

(Unless they are planning to revive the Project Horizon with infantry squads on the Moon)

Next second, someone finds oil aka organic burnable matter on the asteroids, and the US Army leases Starships to "search for potential weapons"

! second after that, they divert an asteroid onto Mars, aka nuking it.

[magnemoe]

17 hours ago, tater said:

First they'd need to decide on a useful crew for it as a test vehicle. I'm not saying Starship as a class needs LES, I'm saying that for early human rating, it would be sensible. A test crew might be 2-8 people? Even if that ended up adding the total loaded mass of a Crew Dragon to the vehicle, it barely scratches the capability since I don't see the crew vehicle as also used for cargo (to space, clearly different if you land it on the Moon, etc).

Whatever that number is determines the size. The vehicle is so overbuilt that the mass doesn't matter much, honestly. I'd make the flight deck at the nose a capsule that can separate in an emergency (same mold line as Starship). Solids are likely the safest, else hypergolics like Dragon 2.

We have to remember that the crew vehicle is built as a sort of "colonial transport" notionally, but in the real world, nothing even close to the theoretical number of passengers will ever be on it (forget P2P for now, think of it as a moon/mars vehicle (the latter even less likely any time soon)). So if it can hold 100 people and 100 tonnes of their cargo, and bring that with refilling to the Moon (and just the people back), then what is the capability with say 6 people, and just a few tonnes of cargo?

An dragon would not work well since you have no way enter the lower part. Something more like the new Shepard pod would work just as well. You would loose the ability to deorbit independently. 

[DDE]

1 hour ago, magnemoe said:

An dragon would not work well since you have no way enter the lower part.

That requires a minor modification previously done on a flown Gemini capsule.

[tater]

1 hour ago, magnemoe said:

An dragon would not work well since you have no way enter the lower part. Something more like the new Shepard pod would work just as well. You would loose the ability to deorbit independently. 

I was thinking of a system for failure during launch, or after reentry. With no abort system, a failure at any point is fatal, with a system that covers pad to orbit, and post reentry to landing seems to be the most bang for the buck.

[Mad Rocket Scientist]

10 hours ago, Xd the great said:

Next second, someone finds oil aka organic burnable matter on the asteroids, and the US Army leases Starships to "search for potential weapons"

! second after that, they divert an asteroid onto Mars, aka nuking it.

The real WMDs were the friends we made along the way.

[magnemoe]

18 hours ago, tater said:

I was thinking of a system for failure during launch, or after reentry. With no abort system, a failure at any point is fatal, with a system that covers pad to orbit, and post reentry to landing seems to be the most bang for the buck.

My thought to, it vastly simplify stuff. 

19 hours ago, DDE said:

That requires a minor modification previously done on a flown Gemini capsule.

It worked for Gemini as it only had the heat shield in back. Dragon has an integrated service module in lower part.  Now add that the side of starship and the escape pod not the bottom will be heated during normal reentry. 

[DDE]

53 minutes ago, magnemoe said:

Dragon has an integrated service module in lower part.  Now add that the side of starship and the escape pod not the bottom will be heated during normal reentry. 

Well, in this design it's an option. But so is creating a tunnel through the equipment at the bottom of the pod.

[Xd the great]

Is someone suggesting to add a fully functional dragon v2 into a cargo starship?