SpaceX makes rocket science look easy: Falcon 9 passes tests

@Dave Re: How many times?

So, I get 6 down votes for saying the tech is neat and its a good start, but questioning how many times could it be reused ???

;-)

To your point, yes sitting on top of a rocket is still a risky endeavor. I get that and while I'd do it, my wife would kill me for even thinking about it.

However my point was that even if they could constantly land it... we have a strengths and materials problem where components will eventually fail after so many uses.

How could they test this? I mean, depending on the payload, even insured, there's going to be a cost for Space X and that has to be balanced out against the manufacturing costs and the savings from reuse.

That's not rocket science but strictly bean counting and risk assessment. One would have to have a bunch of these being reused, and even after examining them for stress fractures and failures... extrapolate their life and then divide by 2 for a safety factor. (e.g. if its safe to use up to 10 times, limit its reuse to 5 and then melt it for scrap...)

You bring up another issue.

While I don't know you... but you do realize that you could get the shot in the arm or anywhere. Most likely the flight attendant will be male so if you want to pull your shorts off and get a long needle in the buttox... who am I to judge? ;-)

Personally, I'd skip breakfast and travel on an empty stomach.

Re: How many times?

Note the Dragon capsule survived the accident, but was not programmed to deal with failure and simply followed a ballistic trajectory hitting the Atlantic at 600 MPH or so. Another RUD.

With no doubt Space X engineers spent thousands of hours going over this rocket. X raying parts, sending probes into the combustion chamber, fuel tanks, turbo pumps and so on. Every bolt and screw tested as well. They know where weak point, and strong points are, and will adjust manufacture of ongoing F-9's accordingly.

I'd keep this one, and fire the next one landed, and checked out for 200 seconds, full on. See if something breaks. If not its power systems are proven robust enough for another run. Tanks and structure another question. You can only test this with another go. This is just a step. I figure ten recoveries, and half a dozen flight tests will have to occur before trying to commercially sell a used rocket flight. First using a Dragon programmed to save itself in case of an accident. The second stage will be brand new. In addition I would not try and recover the first re-use flight. Just put up a payload made up of experiments put forward by college and university engineering students. See what they can cook up. For one I'd love to put my much dreamed about satellite that incorporates a magnetic propulsion system on board. Hall thrusters to orientate. A small 400 pound thing that can be built in the garage. I bet there are thousands of students who'd jump at this chance. Paying for it? The students pony up fuel and range costs though university, grant, and crowd funding. Space X the second stage and its staff. Just a Doc Brown moment.

This was a big deal. Blue Origin doing it proves landing is more than possible. When the next F-9 lands it will be a ULA and ESA shattering moment...

Re: How many times?

> "...since no one has ever tried to design a big engine specifically to be reused a lot."

Well, except for the shuttle engines. Oops.

Re: How many times?

I hope we are all familiar with the failure bell curve.

The idea that there is a bell curve in the failurerate/launchcount graph (for any given subset of devices) is an unwarranted assumption. Time will tell - if SpaceX takes off.

Re: How many times?

It's worth mentioning that even if a Merlin engine fails it doesn't really matter. The Falcon 9 is designed to be able to continue with eight engines if one does conk out. (Presumably that would mean the Falcon Heavy could cope with up to three engine failures?)

We've already seen this happen: on one earlier launch an engine conked out mid-flight, and the Falcon 9 continued and successfully put the primary payload in the correct orbit. Extra fuel was used which meant the chances of getting the secondary payload to its correct orbit dropped from 99% to 95%. NASA decided that 95% wasn't good enough and refused permission for SpaceX to continue with the secondary payload... I still count that as a solid success for the Falcon 9's ability to handle an engine failure.

Re: Needs a name

Sausage-fest?

Bukkake?

Re: Needs a name

Lets hope they don't suffer from dysfunction or there will be some unsatisfied astronauts...

Re: Needs a name

"Given the obvious, phallic shape of the things, the only sensible thing to call them would be an erection of boosters."

Naughty boy. But this is about the going-down-phase, that's like the opposite of erection...

Re: Cost

Replying a week later but at least I'll be able to find it next time...

Actually, if that 16 million is for the first stage rather than the whole F9 it does fit with advertised rates. A standard launch is being priced at 60 million, a Heavy launch 90. It has been suggested that the first stage makes up two thirds of the hardware cost so with a fixed cost per launch (y) plus a hardware unit cost (x) we have F9R as 3x + y = 60 and F9H as 7x + y = 90. Solving that gives x = 7.5 making each first stage 15 million, 22.5 million (15 + 7.5) for a complete F9R and 52.5 million (3 * 15 + 7.5) for the F9H. It also means there's an overhead of 37.5 million for each launch going into range payments, pad rent, payload integration and company profits.

Re: Pretty soon....

Pineapple on pizza is just wrong; see the instructional video:

Futurama - Pineapple pizza

I use my second hand rocket all the time.

OK I admit, more than second.

Re: Second-hand Rockets

That was my first thought too, why not re-launch this rocket empty or with a nominal payload to see how it performs?

Re: Second-hand Rockets

"Seems a shame to put this one in a museum. " ...

One of the great things about the Space X approach to this is that the ongoing commercial launches will supply them with a wealth of used first stages to experiment with.

Re: Why ar they so sooty and what is that hairy stuff?

They also run rich because leaving significant diatomic hydrogen and carbon monoxide in the exhaust stream is more beneficial for efficiency than burning all the way to water and carbon dioxide. Running rich also allows you to control the combustion chamber temperature, which in the case of reusable engines is also beneficial.

According to this information, LOX/RP-1 engines run an oxidiser:fuel ratio of ~2.3:1 by mass. Based on the average molecular formula given, ~3.4 kg of O₂ will completely burn 1 kg of RP-1 to H₂O and CO₂, so assuming I haven't made a mess of the calculations, almost a third of the fuel is incompletely combusted, leading to lots of H₂, CO and a bit of free carbon in the exhaust.

Re: Where did it land?

More specifically, it landed on a pad next (ish) to the one it launched from.

Re: would be thrilled to see

Side boosters land first. Fuel is cross fed to the center core. Outer two only run for 120 seconds or so. Center core fires for around 180 seconds longer. Here I suspect a modified oil platform landing makes a lot more sense. A Merlin Vacuum powers the second stage, later perhaps a Raptor variant will take up this job.

Re: would be thrilled to see

Cross feeding is also called Asparagus staging in KSP - and is a remarkably good way of getting stuff off the ground.