SpaceX: General Falcon and Dragon discussion (Thread 8)

[Jcc]

I mean rapidly reusable launch vehicles.. sorry for the sloppy terminology.

If it doesn't consistently come back to the launch site hundreds of times, then it's probably not worth it.

It seems to me that reusing each first stage just a few times would be worth it, depends on the effort needed to prepare it for launch. This is relative too. You could look at the cost of developing reusability and say Spacex would come out ahead by just doing expendables cheaper than anyone else, but a lot of the effort that goes into reusability also makes them more reliable (that may be debatable).

Any way, you do have to assume a lot of launches to make any low cost launcher viable. The vehicles will be produced in volume, but if you can reuse them 3 or more times, you save a lot of manufacturing cost. 10 or 100 times will truly be a new era in space exploration.

[WHAP]

You mean, expendable rockets fail too often.

What other types of rockets don't fail as often as expendable ones?

Theoretically, reusable ones.. otherwise they're not very reusable.

So you criticize expendable rockets for failing too often, but have no actual alternative, just a theoretical one?  Please enlighten us as to how a reusable rocket that doesn't exist and is based on the same technology as existing expendable rockets is more reliable.  Or were you thinking of something other than F9R?  Feel free to move this to a more appropriate thread; just provide the link.

[AncientU]

Assuming that overflight restrictions are based on avoiding large chunks of whatever falling from the sky and making the nightly news because of where they landed as the functional equivalent of "failure," then expendable rockets will always require overflight restrictions. Reusable rockets are fundamentally different. If every car (or plane) that traveled the road (or took off) jettisoned its passengers and crashed into the next available immovable object... but they don't because they are reasonably reliable and reusable.

[dcporter]

QG's position is being slowly morphed into a misrepresentation... Correct me if I'm wrong, but the only thing I believe he was suggesting was that if rockets become more reliable (a presumed result of reusability), then the overflight restrictions may be eased; see for reference: airports. He wasn't criticizing anybody.

[AncientU]

Even a perfectly reliable expendible comes with a 100% guarantee that debris will be falling from the sky. Not so with a reusable -- QG's point, I think.

[meekGee]

You mean, expendable rockets fail too often.

What other types of rockets don't fail as often as expendable ones?

Theoretically, reusable ones.. otherwise they're not very reusable.

So you criticize expendable rockets for failing too often, but have no actual alternative, just a theoretical one?  Please enlighten us as to how a reusable rocket that doesn't exist and is based on the same technology as existing expendable rockets is more reliable.  Or were you thinking of something other than F9R?  Feel free to move this to a more appropriate thread; just provide the link.

I'll explain for QG.

Rockets operate with very low margins, and almost any issue, trivial as can be, results in LOV.  Therefore, pedantic and unparalleled care must be taken when manufacturing them.  Even so, every launch is a game of roulette - was something done wrong?

Look at accidents. Almost always there is a single cause that could have been prevented.

In terms of the famous reliability "bath tub" curve, rockets always fail on the "too young" zone, not on the "too old" zone.

Reusables will take you out of there.  Once a rocket flies, you know that there's very likely nothing assembled wrong, and if you keep monitoring things after each flight, you know that there very likely nothing deteriorating faster than expected.

Therefore reliability will increase.

[hrissan]

You mean, expendable rockets fail too often.

What other types of rockets don't fail as often as expendable ones?

Theoretically, reusable ones.. otherwise they're not very reusable.

So you criticize expendable rockets for failing too often, but have no actual alternative, just a theoretical one?  Please enlighten us as to how a reusable rocket that doesn't exist and is based on the same technology as existing expendable rockets is more reliable.  Or were you thinking of something other than F9R?  Feel free to move this to a more appropriate thread; just provide the link.

I'll explain for QG.

Rockets operate with very low margins, and almost any issue, trivial as can be, results in LOV.  Therefore, pedantic and unparalleled care must be taken when manufacturing them.  Even so, every launch is a game of roulette - was something done wrong?

Look at accidents. Almost always there is a single cause that could have been prevented.

In terms of the famous reliability "bath tub" curve, rockets always fail on the "too young" zone, not on the "too old" zone.

Reusables will take you out of there.  Once a rocket flies, you know that there's very likely nothing assembled wrong, and if you keep monitoring things after each flight, you know that there very likely nothing deteriorating faster than expected.

Therefore reliability will increase.

Exactly! I do not know how many sensors are in the stage, hundreds or even thousands? They even have strain gauges.

So you test-flight it and get data, if they are nominal - very good chance it will work again. Add an engine-out capability, and the future of rocket flight seems much brighter.

To work this way, it should require no "refurbishment" of any kind - otherwise you could break something during refurb.

[simonbp]

If SpaceX makes it through the next couple years without any failed launches, would they be able to launch from New Mexico Spaceport?   That would give them lots of room to land the Falcon Heavy first stages down range.   

That is an extremely good point. There is no technical reason why not, it would mostly be matter of getting permission from the FAA. Exploring the flight envelop with Grasshopper 2 at Spaceport America, hand-in-hand with the FAA, will help enormously.

As far as location, WSMR is about 25 miles due east of SPA, so they'd either have to come to an agreement with the Air Force or fly a dog-leg.

As to why you would bother, the weather out there is rather hard to beat. The only time it really rains is the summer monsoons (July & August), and that's only in the afternoon.

[Robotbeat]

Before you starting thinking that they just need to increase production rates by a factor of 5, go back and look at the number of Falcon 9 launches per year.

2013: 1
2012: 2
2011: 1
2010: 1

That's 5 flights TOTAL over 4 years. What is their real production rate ?
Cores built for engineering tests don't count.

Let's be a little smart, and consider they didn't build 100 Merlin 1D engines without making sure the first one works. There can't be a huge stockpile of these just sitting around.

Expanding the current production by a factor of 4 or 5 only gets you up to around 6 completed Falcon 9s per year.

And check me if I'm incorrect but that's pretty much what they need this year according to what Gwynn and Elon stated at IIRC their last presser.

yep, everything must go perfect this year.

You know, everyone seems to make big predictions of either complete failure or epic success. I predict 3 launches this year, which is neither of those.

[LouScheffer]

In terms of the famous reliability "bath tub" curve, rockets always fail on the "too young" zone, not on the "too old" zone.

Although I agree with your point in general, didn't the last Merlin engine failure on the Falcon-1 happen on an engine with lots of testing, and that was noted as a possible cause in the failure report?  This is the first time I've seen this cause mentioned in a failure report, though.  More often it's a manufacturing defect that slipped through, as you say. 

It would be interesting to look at RL-10 engines, which are commonly used in multi-burn missions.  Over the years, a number have failed on first ignition due to manufacturing flaws, but I can't recall one that failed on the second burn for that reason.  (Maybe someone with better historical knowledge could speak about this.)

[meekGee]

In terms of classic reliability, it was still infant mortality, caused by a manufacturing defect.  "Lots of testing" was I believe less than 3 full mission durations.

And yes, you could still have issues even with a reusable rocket, but the 9 engine design can handle a lost engine, so you have another factor working for you on top of reusability.

[ArbitraryConstant]

Although I agree with your point in general, didn't the last Merlin engine failure on the Falcon-1 happen on an engine with lots of testing, and that was noted as a possible cause in the failure report?

Sure. But on a reusable you can get the engines back and actually know.

Even in the event of an engine out that costs too much gravity losses for boostback it could abort to ocean and you'd still be able to recover the engines.

[Lar]

So you test-flight it and get data, if they are nominal - very good chance it will work again. Add an engine-out capability, and the future of rocket flight seems much brighter.

To work this way, it should require no "refurbishment" of any kind - otherwise you could break something during refurb.

I think there's a slight "matter of degree" to this, in that you have to AT LEAST refuel.

Drawing an analogy with my car (a poor analogy to be sure)... there is a very slight, but non zero, chance I will somehow damage something during the refueling process.Maybe I put a tiny dent in the fuel filler neck that is completely inconsequential.  Maybe I drove over a nail on the way to the gas pump. Maybe I sparked something and the car blew up.

Also my car has some wear elements that do need to be replaced periodically. I change the oil every 3000 miles. I change air filters.  The process of replacing these things may cause damage as well (I had to get a new oil pan once because some mechanic overtorqued the oil drain plug)

My point is that there is no such thing as "NO" refurbishment. But it's a minor point and I agree with your general thrust, the fewer things to monkey with each time, the better. The Shuttle is our canonical example of too many things to monkey with.

Monkeying impacts cost AND reliability.

[meekGee]

Aviation week is carrying this today:
http://www.aviationweek.com/Article.aspx?id=/article-xml/asd_05_13_2013_p01-01-577898.xml

Has anyone been following this process and can add any information?

[Lar]

Aviation week is carrying this today:
http://www.aviationweek.com/Article.aspx?id=/article-xml/asd_05_13_2013_p01-01-577898.xml

Has anyone been following this process and can add any information?

I think this got its own thread. I can't find it right now but I'll edit it in if I can.

[docmordrid]

Aviation week is carrying this today:
http://www.aviationweek.com/Article.aspx?id=/article-xml/asd_05_13_2013_p01-01-577898.xml

Has anyone been following this process and can add any information?

I think this got its own thread. I can't find it right now but I'll edit it in if I can.

I started it earlier, but now it seems AWOL. Someone move it?

[Lar]

Aviation week is carrying this today:
http://www.aviationweek.com/Article.aspx?id=/article-xml/asd_05_13_2013_p01-01-577898.xml

Has anyone been following this process and can add any information?

I think this got its own thread. I can't find it right now but I'll edit it in if I can.

I started it earlier, but now it seems AWOL. Someone move it?

Chris has been editing/moving/moderating/closing/shuffling/trimming a lot of SpaceX threads, it may have been the baby that went out with the bathwater.... PM him?

[GBpatsfan]

While discussing the Falcon 9 with a reusable 1st stage:

this could take a 2.3 tonne spacecraft to geostationary orbit, or a 5 tonne satellite to low-earth orbit, for $40m

http://www.arabianaerospace.aero/article.php?section=space&article=gssf2013-sstl-boeing-and-spacex-show-that-small-can-be-beautiful&utm_source=dlvr.it&utm_medium=twitter

Also these tweets from Arabian Aerospace:
‏

@ArabianAeroNews
#GSSF Spacex $40m Falcon 9 reusable launch will also take a 5 tonne satellite to low earth orbit - available in 2016.

@ArabianAeroNews
#GSSF Spacex hope to introduce recoverable first stage "Grasshopper" rocket in 2016, promising $40m launches, up to 2.3t to geo orbit.

https://twitter.com/ArabianAeroNews/status/332035431845736448
https://twitter.com/ArabianAeroNews/status/332034959965556737

[Spugpow]

40 million per launch seems high for a Falcon that's mostly reusable. Is the second stage that expensive?

[QuantumG]

40 million per launch seems high for a rocket that's mostly reusable. Is the second stage that expensive?

What makes you think costs have anything to do with prices?