SpaceX after they land their first stage?

[bigdad84]

After they finally successfully land their first stage either on land or barge (hopefully June 19th). they will do a full tear down and observation of the rocket stage to see how it did coming back to Earth. My question being, when this becomes routine, are they going to have to re-certify every engine (which plagued the Shuttle program)? Or are they hoping to just say, "let's go again, everything looks okay!".

[Kryten]

Still to be determined, by thoroughly inspecting a few returned stages.

[Rakaydos]

Well, what's the most likely problem if they skip maintanace?

"We have catastrophic failure of engine 5... shutting down engine 9 to balance load. Calculating... we can make orbit by burning longer and using the reserve fuel. Aborting stage recovery attempt and allocating the reserve fuel to reaching orbit."

[AngelLestat]

They save a lot of money in tests, because they know that all works with that stage.. Just needs some revision and check before launch which is nothing in comparison with the checks needed against something which never was tested.

[Kibble]

"We have catastrophic failure of engine 5... shutting down engine 9 to balance load. Calculating... we can make orbit by burning longer and using the reserve fuel. Aborting stage recovery attempt and allocating the reserve fuel to reaching orbit."

If an injector breaks, the fuels could burn closer to stoichiometric ratio, and bad things would happen.

ftp://ftp.hq.nasa.gov/pub/pao/reports/2000/ssme_vol1.pdf

[Rakaydos]

If an injector breaks, the fuels could burn closer to stoichiometric ratio, and bad things would happen.

ftp://ftp.hq.nasa.gov/pub/pao/reports/2000/ssme_vol1.pdf

if I'm reading the paper correctly, the effects were limited to a catostrophic failure of the turbopump, not something that would carry over to the other merlins. That would fall under my stated "catastrophic failure of an engine"

SpaceX's designs are inherently redundant- a failure on a stage recovery flight doesnt force an abort of the primary mission, only of the recovery.

Edited April 16, 2015 by Rakaydos

[Kryten]

I'm not sure you understand just how catastrophic catastrophic failure of a turbopump is. It's easily capable of peppering the entire stage with fragments moving at insane speeds; it's what took out the Antares last year.

[zhollett]

Just saw this post on youtube regarding the failure:

whichtimesarethese

lol, I like this...very very much. Toys of destruction blowing up....Make me smile...I wish failures for all their future endeavor

Then the following post was this:

God Was Bored

+whichtimesarethese? If you want to see rockets blowing up, try Kerbal Space Program, you can blow up whatever you want! As far as reality and making the human race better, try hoping for better from the individuals that are pushing for space to be a safer destination.

Thought I'd post the response, seems KSP is making its way into the world

Video:

[Nibb31]

After they finally successfully land their first stage either on land or barge (hopefully June 19th). they will do a full tear down and observation of the rocket stage to see how it did coming back to Earth. My question being, when this becomes routine, are they going to have to re-certify every engine (which plagued the Shuttle program)? Or are they hoping to just say, "let's go again, everything looks okay!".

The ultimate goal, is refuel and restack. It will be a long time before we get to that routine though.

And fast-turnaround only makes sense if there are high launch rates. When you have one launch per month and a factory that is built to churn out 400 engines per year, there is no point in fast-turnaround.

[Rus-Evo]

Its close but it seems to need wild moves right at the point of landing. Doesn't seem sustainably reliable (to the uninformed watcher)

[NFUN]

Its close but it seems to need wild moves right at the point of landing. Doesn't seem sustainably reliable (to the uninformed watcher)

That stage can't be throttled, so in order to descend it needs to waste some thrust gimbaling laterally.

[Deutherius]

That stage can't be throttled, so in order to descend it needs to waste some thrust gimbaling laterally.

It can. The Merlin 1D engine has a throttle from 70 - 100 %. It's too powerful to hover, even on a single engine, but it can be throttled.

[Bill Phil]

If only the Merlin had a total burn time capacity of 1995 seconds... then maybe reuse could be possible.

Reusing rocket engines typically involves taking them apart and putting them back together with replacements.

[AngelLestat]

Reusing rocket engines typically involves taking them apart and putting them back together with replacements.

No.. if you touch something that is working.. you have the chance to introduce a problem.

If it works.. it works. A simple review and system study it will be enoght.

The engine design is to stand like 15 (I dont remember) launches without remplacement.

This is not a F1 car where the engine only last 1 race.

Also you can test all systems combined just 1 time... in the launch.

[Bill Phil]

No.. if you touch something that is working.. you have the chance to introduce a problem.

If it works.. it works. A simple review and system study it will be enoght.

The engine design is to stand like 15 (I dont remember) launches without remplacement.

This is not a F1 car where the engine only last 1 race.

Also you can test all systems combined just 1 time... in the launch.

The engine needs to be checked. The past shows that engines don't like reusability.

If it works, then it works, yes. But you have to prove and make sure it works.

If so, it needs to be able to handle thousands of seconds of burning. Unless they replace some parts.

Testing at launch will be looked down upon. Engines, when reused, have to be basically rebuilt. That's not efficient. (that's why I doubt SpaceX will be the "savior" of rocketry...)

[Rakaydos]

The engine needs to be checked. The past shows that engines don't like reusability.

Engines like the SSME that wernt designed for reusability dont like reusability- they take a lot of money and manpower to recertify. Which suited porkbarrel congressmen just fine.

The merlin is DESIGNED for reusability. The first stage fires 3 times every launch/recovery cycle with no in-flight checking whatsoever, and it is also designed to be cheap to service. Which suits a moneygrubbing corporation just fine.

[Bill Phil]

Engines like the SSME that wernt designed for reusability dont like reusability- they take a lot of money and manpower to recertify. Which suited porkbarrel congressmen just fine.

The merlin is DESIGNED for reusability. The first stage fires 3 times every launch/recovery cycle with no in-flight checking whatsoever, and it is also designed to be cheap to service. Which suits a moneygrubbing corporation just fine.

Engines in general don't like reusability.

The SSME was built because the Shuttle needed an LH2 engine. I would think they would want a resuably-designed engine for that. If not, then NASA isn't very smart. Or was, anyway.

The Orbiter was designed for reusability,too. It wasn't an engine, and had to survive full on orbital reentry, but it was designed for reusability. It took months to refurbish.

Reusability isn't very viable with current rocket technology. It's just not. Some parts are reusable, sure. But you can't just grab your engine and launch it again. You have to re-certify it. On a per flight basis. Not doing that is an idiotic thing to do.

Plus, restarting =/= reusability. The J-2 could be restarted. The RL-10 can restart. But that doesn't add to their reusability.

[Rakaydos]

Engines in general don't like reusability.

The SSME was built because the Shuttle needed an LH2 engine. I would think they would want a resuably-designed engine for that. If not, then NASA isn't very smart. Or was, anyway.

The Orbiter was designed for reusability,too. It wasn't an engine, and had to survive full on orbital reentry, but it was designed for reusability. It took months to refurbish.

Oh, nasa was plenty smart. They had an awesome reusable titanium orbiter with supply bids and everything. Then a certian congressman basically told them. "go back to the drawing board, you have half the budget per orbiter you want, and we're only buying 4 orbiters instead of 10"

Plus, restarting =/= reusability. The J-2 could be restarted. The RL-10 can restart. But that doesn't add to their reusability.

Please elaborate on what you think the difference is. What makes a restartable enging NOT reusable, barring a bad landing? (such as salt water submersion or impact at parachute speeds)

[AngelLestat]

Take like example something so complex as an airplane. They fly all the time, they get 1 check every 1 month approximately, full check without disarm engine and without change parts if they dont need to.

When I take my car to the mechanic, after I leave there is always a big chance that something did not work as assumed.

Sometimes they forget something or they dont adjust all pieces fine. So it may lost some oil, or water, or it may gain a new noise, etc.

The best test that something can have is carry out with is duty. As Rakaydos said, if had a soft landing, not salt water, not reentry heat do it to retro-propulsion; then you just need to check if all connections looks ok, electrical and hoses... Some structural check and thats it.

It will be more reliable to launch a rocket already used without check, than a new rocket with months of checks.

That is why they can save so much money if they accomplish this.

[kerbiloid]

When chemical engines will be replaced with nuke reactor + thermal nozzles, any ship will be reusable SSTO by default - because of its enourmous delta-V budget.

It will need no refurbish at all - because it will just fly slowly and gorgeously to the sky at 100 m/s speed, and then starting a full throttle where the air drag is negligible.

Also at that moments all spaceplane projects will disappear at once.

Until that moment all reusable projects will stay a sandbox game.

[Airlock]

It can. The Merlin 1D engine has a throttle from 70 - 100 %. It's too powerful to hover, even on a single engine, but it can be throttled.

Actually, it can throttle to 40% (down by 40% or down to 40% - not really sure). At least according to a tweet from last year. http://www.reddit.com/r/spacex/comments/24j5dk/merlin_1d_can_throttle_down_to_40_elon_musk/?sort=confidence

[Ralathon]

When chemical engines will be replaced with nuke reactor + thermal nozzles, any ship will be reusable SSTO by default - because of its enourmous delta-V budget.

It will need no refurbish at all - because it will just fly slowly and gorgeously to the sky at 100 m/s speed, and then starting a full throttle where the air drag is negligible.

Also at that moments all spaceplane projects will disappear at once.

Until that moment all reusable projects will stay a sandbox game.

I get the feeling you don't understand much about nuclear thermal rocketry. Also, what does this have to do with falcon 9 reusability?

[kerbiloid]

I get the feeling you don't understand much about nuclear thermal rocketry. Also, what does this have to do with falcon 9 reusability?

When space shuttle was in blueprints, they assumed that it will fly once per two weeks without rebuilding. Dynamic stress and temperatures made to restore it after every flight, spending months for it.

Also, experiments with wings/chutes/engines to save at least the first stage were many times done from 1960-s - with no visible effect yet.

SpaceX - in the best case - will save the first stage and a command capsule of the ship. The second stage will be lost anyway.

To reuse the first stage with human crew somebody must officially confirm that the stage systems feel perfect, it's safe to launch people with it. Without detailed investigation of the stage (taking it to pieces then assembling back) probably no sane manager will confirm this on his own risk.

So, until the flight stresses of a spaceship/launcher will not exceed a regular plane stress, all "reusable" systems stay "restorable" ones.

Edited April 17, 2015 by kerbiloid

[Streetwind]

The engine needs to be checked. The past shows that engines don't like reusability.

If it works, then it works, yes. But you have to prove and make sure it works.

If so, it needs to be able to handle thousands of seconds of burning. Unless they replace some parts.

Testing at launch will be looked down upon. Engines, when reused, have to be basically rebuilt. That's not efficient. (that's why I doubt SpaceX will be the "savior" of rocketry...)

What makes you think that SpaceX will blindly rely on "the past"?

They have their own engine assembly line and their own engine test facility. It would not be farfetched to assume that at this point in their R&D cycle, dozens of Merlin engines have successfully burned for dozens of consecutive mission-length firings, possibly even in full clusters of nine. And if that requires replacing parts, then they know precisely which parts are prone to degradation, what must be done to refurbish after each mission-length firing, and what can wait for a once-per-10-firings general maintenance.

Seriously. This is like, the most basic, most obvious form of homework that SpaceX should be doing And I cannot possibly imagine them not doing it. Heck, their Grasshopper anf F9R-Dev1 test vehicles never swapped engines, they always used the same (set). There are additional stresses involved with returning from actual flights, yes; but those will be examined in the context of knowing exactly how the engines are supposed to behave over their lifecycle. As such, these additional stresses will be much easier to spot, assess, and address.

They have also gone through four major iterations of their engine, with another small tweak coming up this summer. Reflying engines was the goal from the outset. These engines are intentionally designed with many, many firings in mind and have gone through many revisions to ensure that this goal can be reached.

SpaceX is not going to just randomly start thinking about reflying engines after recovering a stage. That process already started over a decade ago. If after all this time they're still advertising the capability to refly engines cheaply, the chance is very good that they will be reflying engines cheaply. Not guaranteed, but very very good.

[Frozen_Heart]

Reusability isn't very viable with current rocket technology. It's just not. Some parts are reusable, sure. But you can't just grab your engine and launch it again. You have to re-certify it. On a per flight basis. Not doing that is an idiotic thing to do.

Merlin engines are already fired twice before they launch. Once individually and once as the full cluster. By your logic they shouldn't then work when they finally come to launch the 'new' stage.

And giving up on something because it is currently not feasible is not they way to advance technology. People need to just keep trying until they find something that works.