SpaceX And/Or Rocketry In General

robl
robl
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RE: This picture ?

Quote:

This picture ?

.... I think they are all static fired b/4 launch still, hence the dirty look of the bottom end.

Cheers, Mike.


Yes that is the picture I was referring to. It reminds me of the scene from one of the Star Trek films where Kirk, Scotty, etc were approaching the "Enterprise" in "dry dock". The camera pans to show the new Enterprise. It looked, how should I say it, too clean, too sterile.

I do notice the "dirt" on the lower portion, but I do not recall any "chrome" on any of the rockets I have watched during launch. I suppose I'll have to pay more attention. I still think it is "pretty".

David S
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http://www.msn.com/en-us/news

archae86
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The NASASpaceflight.com

The NASASpaceflight.com current thread on SpaceX barge landing matters has had a large number of rather detailed posts on repair operations being carried out with apparent speed on the damaged barge.

Unless you are deeply interested in details of welders, ship inspection rules, construction details, and so on, you may not care to spend the time to winnow out what is interesting from the abundant chaff in that thread.

But the message for us here seems to be that SpaceX appears to be seriously preparing the barge landing alternative for another trial on the SES-9 launch. The required repairs are extensive, suggesting that the damage was greater than some optimists supposed.

In deference to the distinction Mike Hewson drew to the difference between a landing failure and a landing gear failure after landing, I'll call this an attempt to get their second successful landing. By the old pilot saying that a good landing is one from which the occupants can walk away, and a great landing is one after which one can reuse the airplane, I'll call this their opportunity for their first great barge landing.

robl
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I am beginning to believe

I am beginning to believe that SpaceX's mission parameters are going to force more launches into a water recovery scenario then a land based scenario. So far we have only witnessed one successful land based recovery and multiple attempts at barge recovery. My initial impression was that land based recoveries would be the norm but with the emphasis being placed on barge recoveries that seems to not be true. No facts to support my position other then SpaceXs past performance. As has been stated and observed, oceanic water recoveries really complicate the recovery effort. Land based recoveries always made sense. If you could return to a point near the launch site then refurbishment costs would be greatly reduced. But barge recoveries, if they can be proven to be successful, will add to the costs of recovery. Not much different then the solids on the shuttle from a cost perspective. And for the most part were intact upon recovery.

mikey
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RE: I am beginning to

Quote:
I am beginning to believe that SpaceX's mission parameters are going to force more launches into a water recovery scenario then a land based scenario. So far we have only witnessed one successful land based recovery and multiple attempts at barge recovery. My initial impression was that land based recoveries would be the norm but with the emphasis being placed on barge recoveries that seems to not be true. No facts to support my position other then SpaceXs past performance. As has been stated and observed, oceanic water recoveries really complicate the recovery effort. Land based recoveries always made sense. If you could return to a point near the launch site then refurbishment costs would be greatly reduced. But barge recoveries, if they can be proven to be successful, will add to the costs of recovery. Not much different then the solids on the shuttle from a cost perspective. And for the most part were intact upon recovery.

I always thought that too! Seems there are LOTS of problems with a barge recovery, whereas a set of LARGE parachutes, and maybe even some air bags, could bring the thing down with little to no irreparable damage. Even aircraft carriers bob and weave on the water like Mohamed Ali doing the rope a dope, and they are fricking HUGE!!! Haven't the Russians been reusing their landing shuttles for many years? They land on land and have for a very long time.

robl
robl
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RE: RE: I am beginning

Quote:
Quote:
I am beginning to believe that SpaceX's mission parameters are going to force more launches into a water recovery scenario then a land based scenario. So far we have only witnessed one successful land based recovery and multiple attempts at barge recovery. My initial impression was that land based recoveries would be the norm but with the emphasis being placed on barge recoveries that seems to not be true. No facts to support my position other then SpaceXs past performance. As has been stated and observed, oceanic water recoveries really complicate the recovery effort. Land based recoveries always made sense. If you could return to a point near the launch site then refurbishment costs would be greatly reduced. But barge recoveries, if they can be proven to be successful, will add to the costs of recovery. Not much different then the solids on the shuttle from a cost perspective. And for the most part were intact upon recovery.

I always thought that too! Seems there are LOTS of problems with a barge recovery, whereas a set of LARGE parachutes, and maybe even some air bags, could bring the thing down with little to no irreparable damage. Even aircraft carriers bob and weave on the water like Mohamed Ali doing the rope a dope, and they are fricking HUGE!!! Haven't the Russians been reusing their landing shuttles for many years? They land on land and have for a very long time.

I was at sea in a fairly nasty storm. The destroyer escort was more like a submarine and the carrier's desk was more like a bow plane on a nuke. It was hard to believe how the ocean owned that carrier. As for SpaceX their mission parameters determine if they can return to a land based recovery vs a barge recovery. They may not be able to return and if they can might not have enough fuel for land based. Its all very complicated. I am now wondering about Blue Origin. They too are proposing launches from the Atlantic Cape, but I have not heard anything about them considering a barge recovery. Maybe its too early. Oh well. I want to experience another land based recovery. It was great!

Mike Hewson
Mike Hewson
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As of this point in time I

As of this point in time I reckon ( or if you like if I was Elon, which I'm not ) the strategy is to launch payloads first and foremost. Always with best effort for the client eg. longest throws if GTO. They have to maintain confidence from the market to deliver that, not forgetting their rather long manifest presently awaiting and one very well publicised payload loss. This places 'experimental engineering', which I define here as any first stage activity beyond stage separation, as optional or as best can effort with whatever thunder remains in the tank to spend.

At a glance I would say that the last effort ( no loop back manouevre ) if feasible was barely so. What the loop back gives you is nulling of downrange momentum ( which is most of it ), while still being able to bleed ( via the hypersonic vanes ) any extra gravitational potential acquired during the course of said loop back. It's a perverse requirement.

[ BTW : The reason it goes up during the loop back is to gain a greater advantage in fuel spent by travelling in higher and thus thinner air ie. you spend less fuel to null that downrange momentum, leaving more for the terminal burn ( compared with going back along the launch track at the same altitude ). This assumes pretty rugged usage of those vanes. ]

You see SpaceX is currently loss leading ie. buying into the market via discount. Little if any profit is currently made per launch when amortized over the entire company history to date. It is quite likely that their manifest is filled with customers who know that it is cheaper than true value. The two key questions going onwards are :

(A) what is the break even point for launch costs including whatever optimisations apply like recover and refurbish etc, and

(B) when do you achieve A ?

if A is rather greater than actual present charge to client ( because you are tossing hardware ) and/or B is more than about five years then someone will go broke trying. Remember that Elon has quite a gaggle of, well, eclectic investors but no dopes among them. Google demonstrated that you could buy a seat on the board, relatively cheaply, and retain enough to later leverage some of the good old vertical integration later on eg. Google's very own satellites ? So Google will reap shareholder return like any other but also have special/private capability probably worth rather more than that in the future. There's got to be an investor discount for launches right ? Not to mention whatever value is in NOT launching a competitor's hardware, or milking them to the point of mercy if you do ?

In any event it is a business which will require some patient and deep pockets. To my mind a key figure is what fraction of launches to come are to GTO ? Getting high payloads to GTO precludes land return. The client will always want max achievable KE at payload separation ( takes less time to get their gagdet to geostationary by whatever secondary thrust they employ ) and that binds to either no recovery or downrange barge recovery. That then decides whether you toss an entire first stage - the most expensive bit by the way - or recoup that manufacturing cost via re-use for another client. Or put another way, a first stage doesn't begin to repay SpaceX beyond its construction costs at least until it is re-launched with another revenue gaining payload. And yes, you must factor in all the turn-around fuddling.

Now it may well prove to be true that return to barge is too chancy, keeping in mind that you can lose the barge as well with a really bad one. As already mentioned there is value in minimising loss by deliberately bunting a crappy terminal profile away from the barge, rather than damage the barge in addition to a then inevitable first stage wreck. If so then the most obvious ploy is to lengthen ( again ) the first stage barrel. Having done that to some spec then (i) inform clients of their maximum available KE at some height so then (ii) you can always bring your first stage back to ground. But we are still stuck with that 200GJ swing b/w barge to land return, and that 200GJ is in turn the difference b/w an LEO vs GTO insertion.

As for Blue Origin they have simply made many choices binding then towards another aim entirely, and can't be compared to SpaceX here. Their agenda is different and good on them for it. They need alot more work to come up to even LEO delivery ie. at minimum another 200GJ of KE available at 100km. They may well replay/rediscover the Space Shuttle design problem of using H2/LOX : you can't use that alone to achieve meaningful orbit. The energy per volume just isn't there.

Russia had ( as the USSR ) and still has the advantage of the span of a huge continent* to launch and recover across without much comeback from, shall we say, unhappy inhabitants. Indeed the ideal combo would be a SpaceX type operation on such soil. But don't ask me to live under the downrange track. Indeed in the Cold War they were routinely spraying the countryside with some pretty nasty exhaust from hypergolics.

Cheers, Mike.

* Australia comes to mind as well. But as a precondition you would have to find a cognitively lucid layer of government anywhere within, plus probably Federal, State and local simultaneously so for some given region. Best of luck there.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

archae86
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Some of this barge vs. land

Some of this barge vs. land landing vs. no landing stuff might best be thought of as part of "right-sizing" one's launcher.

With historic launchers there was a tendency to size the primary vehicle for a big piece of the market pie, and tack on extra stuff (usually but not always solid-fuel rockets attached at the sides) to handle some missions requiring more smash.

As the design tried hard for efficiency at the primary point, these "plussed-up" configurations are typically considerably less efficient than the primary one, but people figure they beat designing, qualifying, and keeping up-to-date extra models.

What seems new in the SpaceX model is the re-use considerations give them a somewhat similar opportunity to "plus-down". The limiting capability mission gets all the gusto the rocket has to offer. A somewhat less challenging one gets a deep downrange recovery attempt, with a more expensive recovery fleet operation and perhaps lower probability of success. Next step down--or maybe a continuum, is barge recovery closer and closer to the launch site, with more boostback, lower recovery fleet costs, and perhaps higher recovery probability. Lower yet and you can come all the way back to a land pad, perhaps less than a mile from your refurbishment facility. Lower yet, maybe you do without the super-chilled fuel and LOX. A simplicity-minded program manager might well choose to limit the options, banking on repetition to get things right.

However they got there, the current Falcon 9 is a rather big bird by global standards. Oddly, they don't seem to have so far talked much about the traditional form of plussing-up by adding medium size solids. Instead they plus-up by more or less adding a full pair of F9 first stages to the sides and calling it a Heavy.

I'll predict that if the recovery/refurbishment path starts not to look so good (most likely reasons would be excess recovery failures, excess refurbished vehicle failures, or excess refurbishment costs) that SpaceX may put out one or more solid add-on configuration options.

Regarding parachute recovery: bear in mind that dropping into the sea by parachute is going to give a much more thorough salt-water bath than most people thinking about the refurbishment and durability problems would like. It also takes quite large parachutes to get impact speed down to anything remotely near the touchdown rate they are intending (though perhaps matching what they really got on the most recent mission would not take especially big chutes).

Regarding Russian recovery on land and re-use: The Soviet-era shuttle (Buran) made a single un-manned test flight. It certainly was intended for re-use, but ran out of money and support before even making a second flight. Their Soyuz capsule is the sole current human-rated transport to and from the ISS. It does indeed land on land, using parachute supplemented by a last-second braking rocket set. It is not re-used. The fraction of the launch vehicle which brings the crew to earth (generally in Kazakhstan) is very small.

mikey
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RE: Regarding Russian

Quote:

Regarding Russian recovery on land and re-use: The Soviet-era shuttle (Buran) made a single un-manned test flight. It certainly was intended for re-use, but ran out of money and support before even making a second flight. Their Soyuz capsule is the sole current human-rated transport to and from the ISS. It does indeed land on land, using parachute supplemented by a last-second braking rocket set. It is not re-used. The fraction of the launch vehicle which brings the crew to earth (generally in Kazakhstan) is very small.

Hmmm I did not know that!!!

Chris S
Chris S
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Why don't people just build

Why don't people just build generation 2 of the original Space Shuttles and be done with it. All this faffing about landing vertically is a waste of time, and Richard Branson is away with the fairies.

Build on what worked before but simply became out of date and end of life.

Waiting for Godot & salvation :-)

Why do doctors have to practice?
You'd think they'd have got it right by now

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