Author Topic: SpaceX First and Second Stage Re-usability (THREAD 1)  (Read 829920 times)

Offline telomerase99

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Given that in both attempts now with the Falcon 1 and Falcon 9 the first stages have either broken up on re-entry or "gotten cooked."

How realistic is it that the company will have success with first and second stage re-usability? Is it likely that inflatable kevlar heatsheilds will be necessary? Does anyone have any more information as to the environments that the First and Second stages will have to overcome in order to survive re-entry?
« Last Edit: 05/18/2013 03:39 pm by Chris Bergin »

Offline edkyle99

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Re: SpaceX First and Second Stage Re-usability
« Reply #1 on: 06/09/2010 02:41 am »
Does anyone have any more information as to the environments that the First and Second stages will have to overcome in order to survive re-entry?

I don't know the details, but I suspect that one way to simulate the forces of reentry here on the ground would be to set you car on fire, point it toward a concrete wall, and floor the accelerator.  Or something like that.

 - Ed Kyle
« Last Edit: 06/09/2010 02:42 am by edkyle99 »

Offline mr. mark

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Re: SpaceX First and Second Stage Re-usability
« Reply #2 on: 06/09/2010 02:55 am »
I think Spacex should give up on reusing stages. Falcon 1 works well now  after 2 successes and Falcon 9 is on the way to doing good things as well. There is enough margin in price where they can stay competitive without stage recovery.   

Offline SpacexULA

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Re: SpaceX First and Second Stage Re-usability
« Reply #3 on: 06/09/2010 02:59 am »
I think Spacex should give up on reusing stages. Falcon 1 works well now  after 2 successes and Falcon 9 is on the way to doing good things as well. There is enough margin in price where they can stay competitive without stage recovery.

SpaceX is booked for the next 3 years, and as far as I know they don't have a single payload that approaches their max lift for the vehicles.

If you are going to have 15-20% margin, why not do some research with it?  More is learned from trying and failing than would be learned by following your advice.
No Bucks no Buck Rogers, but at least Flexible path gets you Twiki.

Offline beancounter

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Re: SpaceX First and Second Stage Re-usability
« Reply #4 on: 06/09/2010 03:07 am »
I doubt SpaceX will give up on reusability.  Elon mentioned that they have always had it as part of the plan to reduce costs and get to the 10x less cost per kg into orbit so although it may have been delayed, it won't be eliminated.  Just 'cause it's hard, doesn't mean it's impossible.

It's quite likely that the 2nd stages reentered in an uncontrolled manner so that the aerodynamic forces inflicted on the stage exceeded the structural integrity of the units.  SpaceX will have to work on finding a method that aligns the stage that minimises aerodynamic forces - maybe a small heavy drogue or some such.  But they're smart so I believe that they'll ultimately arrive at a cost-effective solution.
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Offline jhoblik

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Re: SpaceX First and Second Stage Re-usability
« Reply #5 on: 06/09/2010 03:57 am »
I think it will be possible to save  first stage. Space shuttle SRBs are regularly parachute back to Earth.

I am guessing two possible scenario of failing:
1/Time between separation and second stage ignition was aprox. 7 second. Second stage was at that time not farer then length of first stage, aprox. 30 meter (100 feet, max  150 feet). As I remember parachute are in interstage on the side. I am worry at that time exhaustion of second stage heat it to hundreds C.
2/First stage failed and broke during slowing down, probably because unstable, tumbling fall.

Why SRB is easier to save:
- it fall from lower altitude and lower speed
- SRB separate and still fly far from space shuttle before parachute are exposed.

Solution:
I could see solution as Kevlar balloon in the interstage. During separation will inflate and shield inner parts of interstage.
During slowing down, could stabilize and slow faster before hitting thicker parts of atmosphere.

We have to understand this is brand new problem(inline rocket and reusing first stage, expose to plume of the second stage), that nobody so far  try to solve.

Offline zaitcev

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Re: SpaceX First and Second Stage Re-usability
« Reply #6 on: 06/09/2010 04:00 am »
I am sure that Ares SRB was given a rotation post separation for a reason, and I speculate that the reason was to make it stable during the re-entry (meaning not letting it re-enter either end first, but sideways). Speculating further, this rotation and orientation makes it shed more of the velocity higher up in the atmosphere and thus make the peak load smaller. Something for folks tasked with reusability of F-9 to consider, perhaps.

Offline SpacexULA

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Re: SpaceX First and Second Stage Re-usability
« Reply #7 on: 06/09/2010 04:02 am »
Why SRB is easier to save:
- it fall from lower altitude and lower speed
- SRB separate and still fly far from space shuttle before parachute are exposed.

I think you might want to add that the SRB walls are practically armor.

IF the reason that the Falcon 1st stages are falling apart on reentry is lack of rigidity, that's going to be a challenge to correct.
No Bucks no Buck Rogers, but at least Flexible path gets you Twiki.

Offline savuporo

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Re: SpaceX First and Second Stage Re-usability
« Reply #8 on: 06/09/2010 05:28 am »
We have to understand this is brand new problem(inline rocket and reusing first stage, expose to plume of the second stage), that nobody so far  try to solve.
Yeah, so far SpaceX has been going with the tried and true, technology wise .. Now where is that NACA when you need it ?
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Offline Oberon_Command

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Re: SpaceX First and Second Stage Re-usability
« Reply #9 on: 06/09/2010 05:52 am »
I am sure that Ares SRB was given a rotation post separation for a reason, and I speculate that the reason was to make it stable during the re-entry (meaning not letting it re-enter either end first, but sideways). Speculating further, this rotation and orientation makes it shed more of the velocity higher up in the atmosphere and thus make the peak load smaller. Something for folks tasked with reusability of F-9 to consider, perhaps.

Would that help keep the parachutes from getting cooked by the second stage, too?

Online ugordan

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Re: SpaceX First and Second Stage Re-usability
« Reply #10 on: 06/09/2010 06:57 am »
If you are going to have 15-20% margin, why not do some research with it?  More is learned from trying and failing than would be learned by following your advice.

Exactly. Especially since they already have plenty of recovery-related hardware so don't need to reinvent the wheel, but can incrementally tweak their approach to find out what works and what doesn't.

I wonder if any how many cork tiles fell off during the launch and if that had any effect on the stage breaking apart.
« Last Edit: 06/09/2010 07:17 am by ugordan »

Offline telomerase99

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Re: SpaceX First and Second Stage Re-usability
« Reply #11 on: 06/09/2010 07:10 am »
I was hoping that NASA would allow SpaceX to work with the technology developed for landing larger vehicles on Mars which was tested in 2009 in the IRVE.
(NASA Website)

The Inflatable Re-entry Vehicle Experiment, or IRVE, looks like a giant mushroom when it's inflated. The inflatable heat shield is a silicon-coated Kevlar aeroshell is vacuum-packed inside a 16-inch (40.6 cm) diameter cylinder, but once it unfurls and is pumped full of nitrogen it is almost 10 feet (3 m) wide.

If this were inflated just below the 9 engines it seems like it could protect the engines and provide for optimal trajectory. Worth a shot no?

Offline Garrett

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Re: SpaceX First and Second Stage Re-usability
« Reply #12 on: 06/09/2010 07:35 am »
A lot of speculating so far on this thread imo.

The first stage parachutes failed to open and that is the principal explanation SpaceX has given for why the first stage was destroyed on re-entry. The engineers will have data and may even recover some of the first stage for analysis. I would presume that they will continue with their current approach until it executes according to plan, i.e. the parachutes actually open as designed. Then, and only if necessary, will they consider other options/improvement. I don't think I'm speculating too much here.

For this discussion it would be nice to have some figures, which I can't seem to find right now: What was the altitude of Falcon 9 at first stage separation? And what velocities would the first stage have attained as it re-entered? 

I wasn't aware that SpaceX hoped to eventually recover the second stage. I thought it was only the first stage?

Cheers,
« Last Edit: 06/09/2010 07:39 am by Garrett »
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Online ugordan

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Re: SpaceX First and Second Stage Re-usability
« Reply #13 on: 06/09/2010 07:49 am »
The first stage parachutes failed to open and that is the principal explanation SpaceX has given for why the first stage was destroyed on re-entry.

No, the principal explanation given by SpaceX was that the stage broke up during reentry which means the parachutes didn't even get the chance to fail.

Offline Garrett

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Re: SpaceX First and Second Stage Re-usability
« Reply #14 on: 06/09/2010 11:52 am »
The first stage parachutes failed to open and that is the principal explanation SpaceX has given for why the first stage was destroyed on re-entry.

No, the principal explanation given by SpaceX was that the stage broke up during reentry which means the parachutes didn't even get the chance to fail.
I've been reading conflicting reports. Did SpaceX receive telemetry which indicated that the stage broke up?
Some recent articles have reported an "incomplete parachute deployment and resulting impact damage to the first stage":
Four Companies to Watch in the Brave New Commercial Space Mission Era
Falcon 9 Nails Orbit - First Stage Slams Hard into Atlantic
« Last Edit: 06/09/2010 11:56 am by Garrett »
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Offline jhoblik

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Re: SpaceX First and Second Stage Re-usability
« Reply #15 on: 06/09/2010 06:49 pm »
Thank you for your info, I didn't know it.
After your comment I remember when ARES 1 fall it was rotating I thought it because error.

I am sure that Ares SRB was given a rotation post separation for a reason, and I speculate that the reason was to make it stable during the re-entry (meaning not letting it re-enter either end first, but sideways). Speculating further, this rotation and orientation makes it shed more of the velocity higher up in the atmosphere and thus make the peak load smaller. Something for folks tasked with reusability of F-9 to consider, perhaps.

Offline Robotbeat

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Re: SpaceX First and Second Stage Re-usability
« Reply #16 on: 06/09/2010 07:43 pm »
The first stage parachutes failed to open and that is the principal explanation SpaceX has given for why the first stage was destroyed on re-entry.

No, the principal explanation given by SpaceX was that the stage broke up during reentry which means the parachutes didn't even get the chance to fail.
I've been reading conflicting reports. Did SpaceX receive telemetry which indicated that the stage broke up?
Some recent articles have reported an "incomplete parachute deployment and resulting impact damage to the first stage":
Four Companies to Watch in the Brave New Commercial Space Mission Era
Falcon 9 Nails Orbit - First Stage Slams Hard into Atlantic
hmmm... Similar recovery failure to the Ares Ix SRB, if some of your sources are correct.

Another possibility: part of the cork flew off, exposing the tank to heating which caused the Al-Li alloy to weaken and blow-out from internal pressure. Lack of internal pressure caused the whole thing to buckle from aerodynamic forces. It's possible the parachutes still opened, though incompletely.

EDIT: and if the first stage isn't already in a couple pieces by the time the parachutes deploy, the forces from the parachutes would probably rip the whole thing in half as the thrust structure and nine Merlins plummet to the ocean and then to the ocean floor. (How deep is it there, btw?)
« Last Edit: 06/09/2010 07:51 pm by Robotbeat »
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Online ugordan

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Re: SpaceX First and Second Stage Re-usability
« Reply #17 on: 06/09/2010 07:49 pm »
It's possible the parachutes still opened, though incompletely.

No parachutes were reported visible in the debris field.

Offline kevin-rf

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Re: SpaceX First and Second Stage Re-usability
« Reply #18 on: 06/09/2010 08:14 pm »

No parachutes were reported visible in the debris field.

Source?
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Offline FinalFrontier

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Re: SpaceX First and Second Stage Re-usability
« Reply #19 on: 06/09/2010 08:19 pm »
The first stage parachutes failed to open and that is the principal explanation SpaceX has given for why the first stage was destroyed on re-entry.

No, the principal explanation given by SpaceX was that the stage broke up during reentry which means the parachutes didn't even get the chance to fail.
Protective cork or 'stage alignment' failure it sounds like to me. ACS failed to properly align 1st stage for rentry perhaps?
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