SpaceX long-term stage processing goal = 48 hour turnaround

[macpacheco]

Could SpaceX remove redundancy as well as redesign over-engineered parts as more stages are returned and studied?

Could you eventually take significant weight off of the Falcon given reusability?

Its more likely SpaceX will add redundancy structural/thermals/wear margins to allow for more reuses.

[Rocket Science]

How are there STILL people who think that it might be impossible for a Falcon 9 booster to be reused (i.e. even after tweaks to the design)?

The "Anti-rocket-reusability Law of the Universe" hypothesis. I just don't get this.

I can only speak for myself Chris, but first he has to actually recover, re-fly it on multiple occasions and then demonstrate the economics of doing so. My opinion of Elon has always been is “don’t tell me, show me…” and when he does I will always commend he for doing so. Even more, is that he "is not" doing it for the most part at the taxpayer expense as with other X programs. He has earned "a well done and carry on" in my book.

[guckyfan]

Could SpaceX remove redundancy as well as redesign over-engineered parts as more stages are returned and studied?

Could you eventually take significant weight off of the Falcon given reusability?

Its more likely SpaceX will add redundancy structural/thermals/wear margins to allow for more reuses.

You are making a big assumption here. The assumption that they have not added margines to cover those contingencies. I assume they did add margins and may find they may need to increase those margins on some points and may be able to shed margins on other points. I make this assumption because they were building the stage for reuse. After all we do know that the second stage shed margin after they decided not to reuse it.

[woods170]

Why? Just being about to inspect engines that have flown is worth a lot.

That can be done on a test stand.

You have to recover the engines first.  Also, inspection of just about everything else on the stage after flight is an opportunity that they haven't had before.

don't even need to fly the engines.  Just run them on the test stand.    That will provide the data needed.

I beg to differ. There are quite a few variations in conditions that an engine does not see on a teststand. First flight of Ariane 5 ECA  is just one example that can testify to that.

[JasonAW3]

Why? Just being about to inspect engines that have flown is worth a lot.

That can be done on a test stand.

You have to recover the engines first.  Also, inspection of just about everything else on the stage after flight is an opportunity that they haven't had before.

don't even need to fly the engines.  Just run them on the test stand.    That will provide the data needed.

I beg to differ. There are quite a few variations in conditions that an engine does not see on a teststand. First flight of Ariane 5 ECA  is just one example that can testify to that.

Look, Engineering is a science, but that doesn't mean that there isn't an element of both art and luck to it.

No matter how well you plan for a situation in spaceflight, sooner or later something is going to happen that was both inobvious and sneaky that will totally ruin your day.  The Falcon 9 explosion from last year for an example.

From the visual info that I got from the pictures of how the Helium tank was set up in the LOX tank, it looks like there was plenty of redundancy that should have allowed the loss of a couple of struts on the flight.  This was obviously not the case, in retrospect.  This has since been corrected.

Whether or not the first stage can handle multiple launches is yet to be seen.  Like I said in another thread.  We're effectively in the Barnstorming stage of developement of reusable launch vehicles.  The Shuttle was the first, mostly reusable craft.  The Falcon 9 is the next.

[Jim]

I beg to differ. There are quite a few variations in conditions that an engine does not see on a teststand. First flight of Ariane 5 ECA  is just one example that can testify to that.

We are talking about engine reusability.  All that can be learned from the test stand.

[meekGee]

Why? Just being about to inspect engines that have flown is worth a lot.

That can be done on a test stand.

You have to recover the engines first.  Also, inspection of just about everything else on the stage after flight is an opportunity that they haven't had before.

don't even need to fly the engines.  Just run them on the test stand.    That will provide the data needed.

I beg to differ. There are quite a few variations in conditions that an engine does not see on a teststand. First flight of Ariane 5 ECA  is just one example that can testify to that.

Look, Engineering is a science, but that doesn't mean that there isn't an element of both art and luck to it.

No matter how well you plan for a situation in spaceflight, sooner or later something is going to happen that was both inobvious and sneaky that will totally ruin your day.  The Falcon 9 explosion from last year for an example.

From the visual info that I got from the pictures of how the Helium tank was set up in the LOX tank, it looks like there was plenty of redundancy that should have allowed the loss of a couple of struts on the flight.  This was obviously not the case, in retrospect.  This has since been corrected.

Whether or not the first stage can handle multiple launches is yet to be seen.  Like I said in another thread.  We're effectively in the Barnstorming stage of developement of reusable launch vehicles.  The Shuttle was the first, mostly reusable craft.  The Falcon 9 is the next.

When people say "can handle reflight", it does not mean there are no issues that need to be addressed after examining this returned stage.

This stage ("1.2") is the best they could do from a design standpoint in order to make it reusable, without actually having a returned core.

It might be good enough. It might need some tweaks.  It most certainly has  extra margins (by the very definition of "margin")

My bet is that the tweaks are minor.

Between what they've learned about propulsive reentry and the about this stage though, they're in a unique position to get to rapid reusability, and given their business model, they can do it very quickly now.

[Jim]

Flight stresses can't be tested on the ground.

What "flight" stresses" wrt the engines?  The engines produced stresses greatly out weigh any produced by flight.  We are not talking about the airframe or the rest of the vehicle.  Putting a engine in a test stand and running it multiple times and for longer durations is going to provide more data on the robustness of the engine than from a few minutes on a few flights.

[Jim]

Yes, the 3 minutes of flight and the instrumentation from the many flights prevented the helium bottle from not breaking free.  Also, flight environments is not the same as vehicle loads.

The accident provided a benefit by pointing out how little data they have on the vehicle.

Why? Just being about to inspect engines that have flown is worth a lot.

That can be done on a test stand.

These two posts look very contradictory to me.

No, they aren't.
a.  I was only talking about the engines and just having the stage return just for inspection (not reuse). There is a difference between engine and airframes.   Engines can be operated on a test stand.  A launch vehicle can't.   
b.  The mods to the vehicle and flight regime of the boost back, entry and landing negate any benefits of booster return for just inspection (and not reuse).

[Senex]

I originally posted this over on the "Refurbishment" thread, but it would seem to be at least as relevant here.  And it may serve to get discussion off of airspace restrictions and back on the subject of processing boosters for re-flight.


While speculation is popular and is often justified by the absence of facts, there ARE some facts available. An earlier reference to the X-15 is highly relevant as it endured a very similar flight regime in terms of stresses (arguably greater). 

In an interesting article, space historian David Portree cites a study that looked at the refurbishment costs of the X-15 program that provides probably the most relevant real-world data we have:


"In November 1966, James Love and William Young, engineers at the NASA Flight Research Center at Edwards Air Force Base, completed a brief report in which they noted that the reusable suborbital booster for a reusable orbital spacecraft would undergo pressures, heating rates, and accelerations very similar to those the X-15 experienced."

"The average X-15 refurbishment time was 30 days, a period which had, they noted, hardly changed in four years. Even with identifiable improvements, they doubted that an X-15 could be refurbished in fewer than 20 days.

"At the same time, Love and Young argued that the X-15 program had demonstrated the benefits of reusability. They estimated that refurbishing an X-15 in 1964 had cost about $270,000 per mission.

"Love and Young cited North American Aviation estimates when they placed the cost of a new X-15 at about $9 million. They then calculated that 27 missions using expendable X-15s would have cost a total of $243 million. This meant, they wrote, that the cost of the reusable X-15 program in 1964 had amounted to just 3% of the cost of building 27 X-15s and throwing each one away after a single flight.

My bold.

http://www.wired.com/2013/05/the-x-15-rocket-plane-reusable-space-shuttle-boosters-1966/

At least two implications can be deduced from this reference:

1. There has been much talk on the forums about the effects of "fatigue" with images of much of the booster requiring rework or even replacement.  Three X-15's flew 199 flights — and average of 66 each.  Just because a Falcon 9 flies high and fast does not mean it will be structurally degraded after a few cycles.

2. The X-15 required weeks of refurbishment.  It is safe to assume that most of that related to mechanical equipment.  That was with technology that had literally just been invented.  In a vehicle designed from the beginning with operating economies in mind, using a relatively mature technology, this might be dramatically lower.

Wrong analogy.  X-15 was an aircraft and designed like one.  Aircraft are reusable.  Design standards have yet to be developed for reusable boosters for fatigues mitigation.

It's not just an analogy — it's an existence proof.  I posted the above in response to the continuing attitude on the part of some people that reusability is debatable/unlikely/impossible. 

Knowing far less than we do today, North American built a cranky, "Rube Goldberg" of a rocket-plane.  They had very little data to base it on.  It flew in a similar environment and flight regime as a first stage booster.  In some ways what they did was harder — it had to carry a pilot.  And they managed to fly 3 vehicles a total of 199 times. 

"Aircraft are reusable." because we have made them reusable!  If we hadn't gone through a generation when civil rockets were based on ICBM's (that you didn't WANT to come back!) we might have taken a different path and been in a different position today.

NOT reusing is untenable.  One day, in the not-too-distant future, we will look back and shake our heads at the idiocy of "single use rockets."

Some days I feel like I am at the 1905 Buggy Whip Convention . . .  "There's no way those auto mobiles is gonna catch on."

[Jim]

NOT reusing is untenable.  One day, in the not-too-distant future, we will look back and shake our heads at the idiocy of "single use rockets."

The issue isn't reuse.  The shuttle did it and so does X-37.  It is issue is cost effectiveness.

[LouScheffer]

I beg to differ. There are quite a few variations in conditions that an engine does not see on a teststand. First flight of Ariane 5 ECA  is just one example that can testify to that.

We are talking about engine reusability.  All that can be learned from the test stand.

A lot, yes, but not all.  Apollo 6, for example, had a vibration problem that only occurred in vacuum (since on the test stand condensation on the cold bellows provided adequate damping).   A similar problem could easily result in a fatigue lifetime that is much less in flight than it is on the test stand.

[Senex]

NOT reusing is untenable.  One day, in the not-too-distant future, we will look back and shake our heads at the idiocy of "single use rockets."

The issue isn't reuse.  The shuttle did it and so does X-37.  It is issue is cost effectiveness.

Agreed.  And I still stand by what I said.  The economics of reuse will overwhelm "disposable." 

[Jim]

It's not just an analogy — it's an existence proof.  I posted the above in response to the continuing attitude on the part of some people that reusability is debatable/unlikely/impossible. 

Knowing far less than we do today, North American built a cranky, "Rube Goldberg" of a rocket-plane.  They had very little data to base it on.  It flew in a similar environment and flight regime as a first stage booster.  In some ways what they did was harder — it had to carry a pilot.  And they managed to fly 3 vehicles a total of 199 times. 

wrong.  They had previous experience and data to base the design.  There were earlier X-planes.  They had a good grasp of the loads and environments involved.  Most of the vehicle issues were in the control systems and not the airframe.

[Jim]

The economics of reuse will overwhelm "disposable." 

Based on what data?

[Jim]

A lot, yes, but not all.  Apollo 6, for example, had a vibration problem that only occurred in vacuum (since on the test stand condensation on the cold bellows provided adequate damping).   A similar problem could easily result in a fatigue lifetime that is much less in flight than it is on the test stand.

That is an integration issue.  And something that would be not be found by returning the vehicle.

[Senex]

Wrong?  Is it wrong to say that they knew less than we know today?  60 years less?

Disposable works for kleenex vs hankies.  How can anyone defend throwing away a $60 m plus precision machine (fill in 747 analogy).

There will be issues.  Yes.  The Comet jet airliner's window openings cracked.  And they solved it and moved on.

Are you saying the problems are going to be economically unsolvable?

[LouScheffer]

A lot, yes, but not all.  Apollo 6, for example, had a vibration problem that only occurred in vacuum (since on the test stand condensation on the cold bellows provided adequate damping).   A similar problem could easily result in a fatigue lifetime that is much less in flight than it is on the test stand.

That is an integration issue.  And something that would be not be found by returning the vehicle.

Nope, it was an engine problem.  See http://heroicrelics.org/info/j-2/augmented-spark-igniter.html for details.  And you could certainly find problems like this by looking for parts on the returned engine that are stretched, bent, or otherwise deformed in ways you have not seen on the test stand.

[abaddon]

Could SpaceX remove redundancy as well as redesign over-engineered parts as more stages are returned and studied?

Could you eventually take significant weight off of the Falcon given reusability?

Its more likely SpaceX will add redundancy structural/thermals/wear margins to allow for more reuses.

It is most likely that SpaceX will do both, in different areas.

[abaddon]

I believe Jim is saying that he expects the Merlin 1D's to be fully reusable without refurbishment.  Because all that is needed is test stand testing and SpaceX has clearly done plenty of that.