Elon Musk confirms Falcon 9 first stage single-stage-to-orbit (SSTO) capable.

[Steel]

1 hour ago, Exoscientist said:

My opinion, SpaceX will not be able land the F9 first stage reliably and
consistently until they give it hovering ability. The argument has been made
that giving the F9 hovering capability would reduce its payload. However,
some simple and low cost modifications using existing technology, no
advanced tech required, would allow hovering and actually increase the
payload:

Hovering capability for the reusable Falcon 9, page 3: hovering ability can
increase the payload of a RLV.
http://exoscientist.blogspot.com/2015/12/hovering-capability-for-reusable-falcon.html

  Bob Clark
 

While this would be great, the issue they have is without a complete engine re-design, the thrust-to weight ratio of the landing stage is always more than 1, meaning hovering cannot be achieved with the current hardware.

 

Your suggestions in your blog are interesting, however I'm unsure of the feasibility.

1. Pressure fed/ idle mode for the engines - This, while technically feasible, is not what the engines have been designed for and thus may require quite extensive redesign. Also just because it was proved to be technically feasible on the J-2 or the LE-5 does not mean it could definitely be done with the Merlins while they're travelling in the wrong direction. Also, as you mentioned, a single Merlin in this mode would not produce enough thrust to get a TWR of 1 - thus meaning SpaceX having to rework their landing sequence to use more than 1 engine (which provides more redundancy, however means there are 9 times as many points of engine failure in an already complex event)

I've just run some numbers, working with the 3% thrust quoted, TWR would be <1 even will all 9 engines running, the engines would need to provide 4-6% to get TWR of 1. Also with this method is throttling possible?

2. Flexible nozzle extensions - the technical difficulties of getting these to work would almost certainly rule these out as a viable option. Firstly you have the issue of getting them to work reliably in a predictable way (could they be relied on to restrict thrust in a controlled and - more importantly - controllable way?). Secondly, can something like this be designed realistically without affecting the performance of the Merlins, while also capable for withstanding both the heat when the engines are firing and also the stress if an aerodynamic reentry?

 

I would imagine that if it transpires that their current method cannot be done reliably, they will can the idea until they come up with Falcon 9 v2 with engines designed to facilitate hover

Edited December 15, 2015 by Steel

[wumpus]

1 hour ago, Exoscientist said:

My opinion, SpaceX will not be able land the F9 first stage reliably and
consistently until they give it hovering ability. The argument has been made
that giving the F9 hovering capability would reduce its payload. However,
some simple and low cost modifications using existing technology, no
advanced tech required, would allow hovering and actually increase the
payload:

Hovering capability for the reusable Falcon 9, page 3: hovering ability can
increase the payload of a RLV.
http://exoscientist.blogspot.com/2015/12/hovering-capability-for-reusable-falcon.html
Paste
  Bob Clark

Not bad ideas, but I suspect that the "retractable nozzle" would get cooked without LOX flowing through it and would add too much complexity with said LOX (or perhaps boiling kerosene, not sure which SpaceX uses).  Mucking with turbopumps seems like another big issue.  If I wanted pressure fed rockets, I'd probably strap some (hybrid* based) RCS thrusters around the rocket (possibly near the top, not sure how the math works for the pendulum fallacy with non-accelerating rockets).

I'd also mention that there are two issues here.  Landing on land and landing at sea.  It appears that SpaceX is well on track to reliably land in a <10m area and keep the rocket vertical.  It isn't remotely clear that the Falcon rocket could even stay vertical if it successfully landed on Feb 11, 2015 (13-20' waves.  Reminds me of some 'impossible' (read lots and lots of reloads) Mun landings with foolishly tall rockets).  Even with calmer seas, barge landings may well require hovering.  And as far as I know, SpaceX only has one landing port on land.  Falcon Heavy needs 3 landing ports.

* hybrid meaning pressure fed NO2 into a rubberish fuel.  Used by SpaceShip1/2 and a host of high end amatures.  Should be a fairly good RCS rocket if you don't need to worry about multiple ignitions.  If the initial ignition is a big issue, they you need hypergolics.  I suspect that using hypergolics would make it harder to get permission to land on Cape Canaveral (I'm not a fan of them myself.  The stuff is condensed liquid evil).

[Nibb31]

I don't think that not being able to hover is a big issue. There is no reason hoverslam can't be made to work. You know your thrust, you know your altitude, and you know your weight. It's just a matter of plugging those 3 parameters into a calculator and you get your burn parameters.

Previous failures were mostly due to landing on a small platform in the sea. I'm pretty sure that they can get it work on land with only some minor tweaking.

[Rakaydos]

50 minutes ago, Nibb31 said:

I don't think that not being able to hover is a big issue. There is no reason hoverslam can't be made to work. You know your thrust, you know your altitude, and you know your weight. It's just a matter of plugging those 3 parameters into a calculator and you get your burn parameters.

Previous failures were mostly due to landing on a small platform in the sea. I'm pretty sure that they can get it work on land with only some minor tweaking.

Who are you and what have you done with Nibb?

[wumpus]

3 hours ago, Nibb31 said:

...

Previous failures were mostly due to landing on a small platform in the sea. I'm pretty sure that they can get it work on land with only some minor tweaking.

This doesn't bode well for the Falcon Heavy then.  On the other hand, I'm not sure what type of cargo SpaceX has contracted to lift with the Heavy: I suspect they don't have nearly the launch schedule.  They might be launching in Houston and landing in Florida by the time Falcon Heavy really *needs* three landing pads (which just might be when Elon Musk says "that's it.  Gas up a few Falcon Heavys, I'm going to Mars.").

[Nibb31]

Hehe... I haven't had much doubts that they will finally get the technical details of recovering rocket stages ironed out. 

It's the economical viability of reusable stages that I'm doubtful about, and the actual ability to cut launch prices by an order of magnitude based on that capability. And all the Mars colony stuff...

[fredinno]

On 12/1/2015, 12:34:07, Apexazimuth said:

I can't believe New Shepard is even being compared to Falcon 9.  One's an orbital launch vehicle, the other is an expensive toy.   The way the press are toting around that high mach number as if it's some kind of achievement is hilarious.  You don't see SpaceX talking mach numbers because their rockets work in ORBITAL velocities.   It's like comparing an unpowered glider to a supersonic jet...

Space Tourism is not an expensive toy.

Edited December 15, 2015 by fredinno

[fredinno]

On 12/2/2015, 1:53:49, Rune said:

SpaceX fanboys aside, what irks me is that insistence on using the word "first". Plenty of reusable rocket vehicles out there. If anything this is the first H2/LOX reusable rocket vehicle. Wait, DC-X. Nope, no firsts on this flight. And I don't think that is the right propellant combination to build a reusable rocket vehicle anyway.

 

Rune. IIRC, the truly first one was the Me-163 Komet, circa 1941.

H2 O2 is easier for engine maintenance,

 

On 12/1/2015, 2:18:12, Kryten said:

It's weird to see all the SpaceX fanboys go from 'reusability is going to make space stupidly cheap' to 'reusibility is meaningless if it isn't going fast enough'. Weren't these the people gushing over grasshopper not too long ago? Do they not realise this is going to be the first opportunity to really work out the economics of reuse?

Fanboyism at work, folks.

[fredinno]

5 hours ago, wumpus said:

Not bad ideas, but I suspect that the "retractable nozzle" would get cooked without LOX flowing through it and would add too much complexity with said LOX (or perhaps boiling kerosene, not sure which SpaceX uses).  Mucking with turbopumps seems like another big issue.  If I wanted pressure fed rockets, I'd probably strap some (hybrid* based) RCS thrusters around the rocket (possibly near the top, not sure how the math works for the pendulum fallacy with non-accelerating rockets).

I'd also mention that there are two issues here.  Landing on land and landing at sea.  It appears that SpaceX is well on track to reliably land in a <10m area and keep the rocket vertical.  It isn't remotely clear that the Falcon rocket could even stay vertical if it successfully landed on Feb 11, 2015 (13-20' waves.  Reminds me of some 'impossible' (read lots and lots of reloads) Mun landings with foolishly tall rockets).  Even with calmer seas, barge landings may well require hovering.  And as far as I know, SpaceX only has one landing port on land.  Falcon Heavy needs 3 landing ports.

* hybrid meaning pressure fed NO2 into a rubberish fuel.  Used by SpaceShip1/2 and a host of high end amatures.  Should be a fairly good RCS rocket if you don't need to worry about multiple ignitions.  If the initial ignition is a big issue, they you need hypergolics.  I suspect that using hypergolics would make it harder to get permission to land on Cape Canaveral (I'm not a fan of them myself.  The stuff is condensed liquid evil).

SpaceX's landing ports have 5 pads.

Also, you can use pressurized O2 as a landing gas, similar to what DC-X did, or just use verniers/ dedicated landing engines attached to that rocket. Both will likely need quite a few modifications.

Edited December 15, 2015 by fredinno

[Apexazimuth]

19 minutes ago, fredinno said:

Space Tourism is not an expensive toy.

I have to disagree.  Space Tourism is a leisure market, as any tourism is.  I'm not judging it by calling it a toy, because leisure and play are critical to the enjoyment of life.

If space tourism is a means to fund advancement in rocketry and space travel infrastructure, then I applaud it.

[Nibb31]

I don't think that space tourism is such a huge market.

Suborbital 5-minute joyrides will be for the Jet Set, which will earn bragging points for the first couple of people who do it. But in the Jet Set, nobody want's to be the second best, so it will wear off once all of the Kardashians have done it. I don't think that's a sustainable business model. Beyond that, who wants to sell their house for a 5 minute joyride ?

As for orbital hotels, they are even less sustainable. People like rich businessmen aren't usually interested in taking long vacations (otherwise they wouldn't be rich), unless they can combine them with business trips. Space isn't the best place to conduct business, and unless they are real space geeks (most of them aren't) they will still prefer touring the Bahamas or the French Riviera on a super-yacht and partying with super-models. Floating in zero-g and looking at the Earth out of a porthole probably gets old after a few days if you have nothing else to do.

 

 

Edited December 16, 2015 by Nibb31

[Rakaydos]

6 hours ago, Nibb31 said:

I don't think that space tourism is such a huge market.

Suborbital 5-minute joyrides will be for the Jet Set, which will earn bragging points for the first couple of people who do it. But in the Jet Set, nobody want's to be the second best, so it will wear off once all of the Kardashians have done it. I don't think that's a sustainable business model. Beyond that, who wants to sell their house for a 5 minute joyride ?

As for orbital hotels, they are even less sustainable. People like rich businessmen aren't usually interested in taking long vacations (otherwise they wouldn't be rich), unless they can combine them with business trips. Space isn't the best place to conduct business, and unless they are real space geeks (most of them aren't) they will still prefer touring the Bahamas or the French Riviera on a super-yacht and partying with super-models. Floating in zero-g and looking at the Earth out of a porthole probably gets old after a few days if you have nothing else to do.

 

 

Il'l point out that Low Earth Orbit gets a decent network connection. A buisnessman at the ISS can conduct the same buisness there that he can in the middle of the Caribbean.

[Nibb31]

12 minutes ago, Rakaydos said:

Il'l point out that Low Earth Orbit gets a decent network connection. A buisnessman at the ISS can conduct the same buisness there that he can in the middle of the Caribbean.

No it doesn't. You actually need a dedicated satellite network like NASA's TRDS or ground stations sprinkled around the globe, but those are not available for commercial usage. TRDS doesn't provide anything like high-speed broadband (it's around 3Mbps with a very high latency). You can't skype from the ISS, but you can transfer files.

[wumpus]

7 hours ago, Nibb31 said:

I don't think that space tourism is such a huge market.

Suborbital 5-minute joyrides will be for the Jet Set, which will earn bragging points for the first couple of people who do it. But in the Jet Set, nobody want's to be the second best, so it will wear off once all of the Kardashians have done it. I don't think that's a sustainable business model. Beyond that, who wants to sell their house for a 5 minute joyride ?

As for orbital hotels, they are even less sustainable. People like rich businessmen aren't usually interested in taking long vacations (otherwise they wouldn't be rich), unless they can combine them with business trips. Space isn't the best place to conduct business, and unless they are real space geeks (most of them aren't) they will still prefer touring the Bahamas or the French Riviera on a super-yacht and partying with super-models. Floating in zero-g and looking at the Earth out of a porthole probably gets old after a few days if you have nothing else to do.

 

 

How long was "air tourism" sustainable during the barnstorming era?  On the other hand, I think the planes were paid for (WWI surplus).  I'm also pretty sure that safety above all else wasn't the watchword of the time.  But those barnstormers always made time for paid flights (of a few minutes a pop).

[Nibb31]

Barnstorming was never a big contribution to air travel. It didn't really boost design and mass production of barnstorming planes, nor did it evolve into a large industry. 

The reason why analogies with air travel fall flat is that there was huge demand for fast transportation from point A to point B before the airplane was even invented, or before rail or ships. People have always needed to travel to real destinations where people live and work, so that they could meet friends and relatives, conduct business, exchange goods, or just visit.

Space is not a destination, it's litterally the middle of nowhere, and people have no reason to go there. Air travel was a solution to a problem. Space travel is a solution to a non-existing problem. With no existing demand, building a mass transport infrastructure to orbit is like building a bridge to nowhere.

[fredinno]

9 hours ago, Nibb31 said:

I don't think that space tourism is such a huge market.

Suborbital 5-minute joyrides will be for the Jet Set, which will earn bragging points for the first couple of people who do it. But in the Jet Set, nobody want's to be the second best, so it will wear off once all of the Kardashians have done it. I don't think that's a sustainable business model. Beyond that, who wants to sell their house for a 5 minute joyride ?

As for orbital hotels, they are even less sustainable. People like rich businessmen aren't usually interested in taking long vacations (otherwise they wouldn't be rich), unless they can combine them with business trips. Space isn't the best place to conduct business, and unless they are real space geeks (most of them aren't) they will still prefer touring the Bahamas or the French Riviera on a super-yacht and partying with super-models. Floating in zero-g and looking at the Earth out of a porthole probably gets old after a few days if you have nothing else to do.

 

 

The  rich elite would ride it, and it would really be more like a very intense roller coaster ride, with the ability to float in space and view stunning view afterwards. In many cases, such a ride would be like another one of their Luxury vacations. Not to mention those people would likely want a new, exciting destination to visit. Why not out of the world, then?

 

Orbital Hotels can also be used for film making, as was proposed for MirCorp, and the Enterprise ISS module. This could generate a little bit extra income for an Orbital Hotel. Also, nobody really said tourist would stay on a long-term trip. They probably would only stay maybe a week to a month. One can also do guided spacewalks, and there is also the experience of extended zero-G. The ultra-rich has already shown themselves to be interested for doing these kinds of trips.

I think the limiter for Orbital Tourism now has to do more with cost, rather than will or need.

1 hour ago, Nibb31 said:

Barnstorming was never a big contribution to air travel. It didn't really boost design and mass production of barnstorming planes, nor did it evolve into a large industry. 

The reason why analogies with air travel fall flat is that there was huge demand for fast transportation from point A to point B before the airplane was even invented, or before rail or ships. People have always needed to travel to real destinations where people live and work, so that they could meet friends and relatives, conduct business, exchange goods, or just visit.

Space is not a destination, it's litterally the middle of nowhere, and people have no reason to go there. Air travel was a solution to a problem. Space travel is a solution to a non-existing problem. With no existing demand, building a mass transport infrastructure to orbit is like building a bridge to nowhere.

One can use suborbital for obscenely fast travel, at the expense of high cost. Which is why costs would likely have to decline quite a bit for that to happen.

[Elukka]

On 12/15/2015 at 6:38 PM, Nibb31 said:

Previous failures were mostly due to landing on a small platform in the sea. I'm pretty sure that they can get it work on land with only some minor tweaking.

That's not right, they were failures with the rocket. The first attempt failed due to an insufficient amount of hydraulic fluid for the grid fins. The second failed due to oscillation caused by laggy control response due to sticky throttle valves. Landing on land is certainly more forgiving, but since those issues have been fixed they should be able to land on a barge just as well.

[magnemoe]

On 15.12.2015 at 8:50 PM, wumpus said:

This doesn't bode well for the Falcon Heavy then.  On the other hand, I'm not sure what type of cargo SpaceX has contracted to lift with the Heavy: I suspect they don't have nearly the launch schedule.  They might be launching in Houston and landing in Florida by the time Falcon Heavy really *needs* three landing pads (which just might be when Elon Musk says "that's it.  Gas up a few Falcon Heavys, I'm going to Mars.").

Falcon heavy will have no problems doing boost back on the two boosters, core stage will require an barge. 

Main problem with an barge landing is that you also have to land on an very small spot 

[wumpus]

1 hour ago, magnemoe said:

Falcon heavy will have no problems doing boost back on the two boosters, core stage will require an barge. 

Main problem with an barge landing is that you also have to land on an very small spot 

After thinking about it some more, I'd guess that the cost in $/kg-to-LEO it would be cheaper to launch a Falcon Heavy, retrieve 2/3s of the boosters (landing the easy ones on land, watching the tough one smack into a barge tilted by waves and fall over).  If a falcon9 launch cost is 60-70% booster, then I'd expect that a falcon heavy has three times the booster costs, but similar costs for everything else.  You could eat the cost of the booster and still come out ahead due to the much heavier payload (assuming you could find a customer), than even a falcon9 with all (1) booster recovered (and reused).

That 30-40% "everything else" cost adds up, and brings most of the euphoria of the landing back to Earth.  My guess is that merlin/falcon 1.2 and 1.3 are going to try to chip away at those numbers, now that they are starting to become the high poles in the tent.  There was never any reason to take them seriously until now.

[fredinno]

2 hours ago, wumpus said:

After thinking about it some more, I'd guess that the cost in $/kg-to-LEO it would be cheaper to launch a Falcon Heavy, retrieve 2/3s of the boosters (landing the easy ones on land, watching the tough one smack into a barge tilted by waves and fall over).  If a falcon9 launch cost is 60-70% booster, then I'd expect that a falcon heavy has three times the booster costs, but similar costs for everything else.  You could eat the cost of the booster and still come out ahead due to the much heavier payload (assuming you could find a customer), than even a falcon9 with all (1) booster recovered (and reused).

That 30-40% "everything else" cost adds up, and brings most of the euphoria of the landing back to Earth.  My guess is that merlin/falcon 1.2 and 1.3 are going to try to chip away at those numbers, now that they are starting to become the high poles in the tent.  There was never any reason to take them seriously until now.

...except that most of the cost of a rocket is labour, something that is not reduced by reusability- there are still maintenance and inspection crews required, replacing the ones building the rockets.

 

Yes, 2nd stage reusability will likely be what Elon is starting to look towards. I'd think he would develop a new, H2Lox or CH4Lox 2nd stage for this, since Falcon 9 is already about as long as it can get- and any wider would likely require barge transportation- something that Elon apparently wanted to avoid, making sure Falcon 9 was the maximum possible diameter for road transport. However, SpaceX is not working towards this at all.

 

Of course, a Raptor-fueled 1st stage is a possibility- but CH4 takes up more space than RP-1, needing greater volume tanks.

 

In conclusion, Elon needs a boat, and probably new tank equipment to reuse 2nd stages. It's safe to assume it'll take a while- after the 1st stage is reused 50 or so times.

[Kerbart]

On 12/16/2015 at 10:36 AM, Rakaydos said:

Il'l point out that Low Earth Orbit gets a decent network connection. A buisnessman at the ISS can conduct the same buisness there that he can in the middle of the Caribbean.

You'd be shocked how import face-to-face meetings still are in modern day business. A vacation can always be combined to meet a few customers or vendors. Unless said customers/vendors decide to join you in the space station... Not so much.

[Bill Phil]

1 hour ago, Kerbart said:

You'd be shocked how import face-to-face meetings still are in modern day business. A vacation can always be combined to meet a few customers or vendors. Unless said customers/vendors decide to join you in the space station... Not so much.

Yeah. The connection of face to face  meetings is much more important.

But telepresence could supplement that, eventually. FaceTime is already a thing, and so is Skype. They're not perfect substitutes, but they do a decent job. Maybe future versions will be even better? After all, Hololens could show a standing person that simulates a meeting. I have no idea, though.

Of course you need a good internet connection. 

Edited January 8, 2016 by Bill Phil

[wumpus]

58 minutes ago, fredinno said:

...except that most of the cost of a rocket is labour, something that is not reduced by reusability- there are still maintenance and inspection crews required, replacing the ones building the rockets.

 

Yes, 2nd stage reusability will likely be what Elon is starting to look towards. I'd think he would develop a new, H2Lox or CH4Lox 2nd stage for this, since Falcon 9 is already about as long as it can get- and any wider would likely require barge transportation- something that Elon apparently wanted to avoid, making sure Falcon 9 was the maximum possible diameter for road transport. However, SpaceX is not working towards this at all.

It wasn't that long ago that SpaceX pretty much admitted that they were never going to return/reuse the Falcon9 (at least for any Falcon <=1.2).  I've never really believed that it was a possibility, and thought that the genius of the Falcon was to reuse the 90% of stuff that only barely scraped space and was moving less than half of orbital velocity.   Also note that the merlin engine is specifically designed for roughly 10 flights.  If you place an engine in the second stage after 9 flights in the booster, there is really no reason to try to recover it (at the painful costs of orbital recovery, not "touching space, yea!" recovery).

Building a CH4Lox stage would make tons of sense if they wanted to start small for the BFR engine.  My guess is that they would/have developed it but aren't/haven't even considered sticking it into the proven Falcon stack.  Sure, that might be a "waste" of engineering.  But the costs of making an engine that works on the bench are nothing compared to building an engine and integrating it into a rocket while being reliable enough to bet $60M rockets & satellites and endanger any manned ratings. If by "not working towards this at all" you mean "not considering mucking with the proven Falcon design" I'd agree this makes sense.

"here are still maintenance and inspection crews required" The official word is that the Falcon is meant to be gas & go, with the assumption that an actual ride into space proves the thing far better than any inspection routine and that maintenance isn't needed.  My guess is that they are finding out if this is true this out as I write this, but we'll see.  One thing to remember is that the ISS supply contract is pretty unique: NASA (+ESA and whoever else wants to pay the bills) appears to pay top dollar for cargo that is easily replaceable.  Typically such contracts include satellites that are as expensive as the launch.  I have no idea if the contractors get multiple tries (Orbital might have wanted to, but I doubt they can afford to blow up another launch site.  SpaceX is unique in having an "extra" booster), but it certainly is an ideal contract for sending up reused boosters.

[Kerbart]

32 minutes ago, wumpus said:

(...) here are still maintenance and inspection crews required" The official word is that the Falcon is meant to be gas & go, with the assumption that an actual ride into space proves the thing far better than any inspection routine and that maintenance isn't needed.  My guess is that they are finding out if this is true this out as I write this, but we'll see.  One thing to remember is that the ISS supply contract is pretty unique: NASA (+ESA and whoever else wants to pay the bills) appears to pay top dollar for cargo that is easily replaceable.  (...)

I doubt “She did fine last week, and we just gassed her up” will count as man–rating and I know you didn’t mean that either.  On the other hand, not every launch needs to be man–rated and Musk has been very adamant that while NASA is a big customer, it is not SpaceX's only customer. The obvious business model for individual Falcon 9 boosters will likely be something along these lines

1. man—rated launches
2. top—dollar unmanned launches (large communications satellites, etc)
3. ISS supply runs
4. lower grade unmanned launches (irridum, gps, etc)
5. cubesat launches
6. college-sponsored satellites
7. cubesat sponsored by a forum of wannabe-space-agency simulator nerds
8. fuel depot for Elon's Mars mission

For each subsequent launch the going rate for the booster will drop (as it wears out and the chances of failure increase) but it will also allow launches to parties that couldn't afford them in the past. Surely you'd be insane to use a booster on it's fifth flight for a crew replacement flight to the ISS (not until there are dozens of such launches proving that there's no risk, at least). But with a booster that's been paid for many times over you can offer launches at extremely competitive rates to parties who are more than happy to run the risk of a failure at that point.

[AngelLestat]

Let me add some to the list:

NovaWurks:  https://www.youtube.com/watch?v=X6BNRX2t2m4
Private rental of satellites services.

SpacePharma: https://www.youtube.com/watch?v=xRX6MT_EWXs

Deorbit reusable costellations: https://www.youtube.com/watch?v=bDgkRsmcSqM

Axelspace: https://www.youtube.com/watch?v=C_T9GKGA7B4
Making and launching your own personal satellite at the cost of an helicopter.