Author Topic: SpaceX Falcon 9 First Landing Discussion--Historic!  (Read 68681 times)

Offline Kabloona

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #220 on: 12/25/2015 09:15 AM »
Plus, what we saw on the F9-21 first stage was not evidence of the stage being on fire, but of combustion products depositing themselves on the outside of the stage.  So the body of the stage could have been at a very reasonable temperature on the way down.
No.  It was on fire.  Flames were visible after engine shut down that lasted for a half-minute at least.  Eyewitnesses also saw flickering flames during the coast phase that followed the reentry burn and preceded the landing burn.  They are visible, barely, in some of the YouTube videos.  The fire was in the vicinity of propulsion section, so was likely engine/propellant related.  Maybe not a big deal, but still something to inspect and possibly repair.

 - Ed Kyle
I wondered if the fire might be from hydraulic fluid used for the grid fins.  Instead of just pumping it out maybe they are burning it off instead, which would explain the fire seen after the re-entry burn and after the landing.  Does any one know how they dispose of the hydraulic fluid?

Spaceflight101 says it is dumped overboard, but it would be dumped at the top end of the rocket, not the bottom. And no rocket I know of intentionally burns off waste hydraulic fluid. At least one rocket has failed because its hydraulic fluid dump stream accidentally caught fire, but I can't remember which rocket it was.
« Last Edit: 12/25/2015 09:27 AM by Kabloona »

Online Coastal Ron

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #221 on: 12/25/2015 06:24 PM »
Plus, what we saw on the F9-21 first stage was not evidence of the stage being on fire, but of combustion products depositing themselves on the outside of the stage.  So the body of the stage could have been at a very reasonable temperature on the way down.
No.  It was on fire.  Flames were visible after engine shut down that lasted for a half-minute at least.

After landing there was a small flame coming from the side of an engine.  I would not characterize that as the entire stage being on fire - it was a small issue in the area of the stage where fire is expected for normal operation.

Quote
The fire was in the vicinity of propulsion section, so was likely engine/propellant related.  Maybe not a big deal, but still something to inspect and possibly repair.

SpaceX does know what the source of the flame was, and it was something that does need to be addressed.  But if you look at the stage it was not the source of the soot and discoloring on the stage (which was even around the circumference, not just on the side with the small flame), and the "stage" was not "on fire".
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Offline cambrianera

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #222 on: 12/25/2015 06:51 PM »
Falcon stages have to have some type of thermal protection on their bases, for engine heating if nothing else
Bolted panels are the thermal protection of the first stage core.
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Online acsawdey

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #223 on: 12/25/2015 07:39 PM »

Plus, what we saw on the F9-21 first stage was not evidence of the stage being on fire, but of combustion products depositing themselves on the outside of the stage.  So the body of the stage could have been at a very reasonable temperature on the way down.
No.  It was on fire.  Flames were visible after engine shut down that lasted for a half-minute at least.

After landing there was a small flame coming from the side of an engine.  I would not characterize that as the entire stage being on fire - it was a small issue in the area of the stage where fire is expected for normal operation.

This is a key difference. If the problem was a leaky fuel valve upstream of the turbo pump, then all this combustion  is occurring in areas that are normally expected to have combustion or exhaust in them. If the fuel path had been compromised somehow, allowing fuel to escape into the Falcon's "engineering spaces", then that would've likely resulted in damage to the stage and possibly loss of the stage.

We don't know which of these occurred. But Elon's assertion that they could put it on the pad and test fire it again right away suggests that it wasn't the latter.

Offline HVM

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #224 on: 12/25/2015 07:47 PM »
To me it's seems to be some of the drains...

Offline Lars-J

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #225 on: 12/25/2015 08:09 PM »
Yep, very likely.

Offline hrissan

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #226 on: 12/25/2015 08:20 PM »
Video analysis of the landing...

I synchronised videos by the "double-flash" at engine shutdown, to a precision of 2 frames.

"Falcon 9 First Stage Landing | From Helicopter": I used the stage height as a normalizing factor.
"SpaceX Falcon 9 Rocket Landing Cape Canaveral Video": I used the altitude of the stage known from the fist video as a normalising factor.
"SpaceX Falcon 9 Launch & Landing HISTORIC EVENT!!!": Time between entrance burn and landing burn is clearly visible - 47 seconds and according to audio of people reaction the entrance burn is about 18 seconds.

Observations: there is definitely 2 regions of deceleration. First ten seconds, and then last 15.

First ten seconds of landing burn deceleration is about 4 m/sec/sec
Last 15 seconds of landing burn deceleration is about 7.5 m/sec/sec. Wow!

Terminal velocity before landing burn is about 150 m/sec.

Offline meekGee

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #227 on: 12/25/2015 08:27 PM »
Video analysis of the landing...


More graphs to come, yes?  The velocity on the second one has a larger deviation.

t/w = 1.7 is nice.  I wonder how much further they can/will push it.
Especially with the initial slow deceleration, they seem to have taken it easy this time.
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Offline macpacheco

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #228 on: 12/25/2015 10:14 PM »
I'm flabergasted by the performance loss due to RTLS.
1st stage can throw S2 at 8000 Km/h with ASDS landing
1st stage can throw S2 at 5000 Km/h with RTLS landing
So it probably could throw S2 at least some 9000 Km/h without any reuse ?

Taking just speed squared as a relative comparison for kinectic energy (assuming same S2+payload weight).
9000Km/h = relative 81 units of kinectic energy
8000Km/h = relative 64 units of kinectic energy
5000Km/h = relative 25 units of kinectic energy

Conclusion is quite simple, it will take a much more efficient rocket to be fully reusable. And a bigger one. Falcon Heavy has a lot of brute force, but too low ISP to make much logic to go for a reusable 2nd stage.

So I'm forgetting about S2 reuse until we have 100% liquid methane rocket. Something like 9 raptor first stage and a single raptor second stage.

But this does show how efficient the total F9R solution is. Even the 1.1 version.

I have to say I'm an even bigger fan of SpaceX as I ever was. Full Thrust F9R, looking good !



Do you think that NASA will learn from SpaceX's example and follow?
Keep in mind that SX has done in 5 years what NASA couldn't do in 50 (not a knock on NASA).
And might it be extrapolated to even bigger launch vehicles?

I hope NASA is put permanently out of the business of designing rockets.
Moving forward SLS should be cancelled.
All launch jobs are contracted in CRS like fashion. NASA certify designs (when very expensive payloads are launched), instead of doing it themselves.
Reuse will allow for newly designed rockets to undergo many reusable test launches, demonstrating reliability before expensive payloads are put at risk, but without wasting a whole rocket just to prove it works.
This concept changes everything.

The other coin of reusable transport aircraft is safety. The fact a B787 or A350 can be flown thousands of times (and are built by the thousands) allows the first one to be test flown and certified with real world data instead of paper certification.

Imagine USAF easy certification criteria of 14 flights becoming the only certification criteria...

Moving forward even space probes and other speciality missions should be designed by the private sector. But that will perhaps take a decade or more to become common practice.

The biggest barrier for that happening will be US congress.


SpaceX got a mass number of 21200 kg to 27 degrees GTO orbit on their Falcon Heavy web page. However they only list pricing for 6.4 metric ton to GTO orbit. Guessing there are no payloads greater than 6.5 metric to GTO in the foreseeable future according to SpaceX marketing people.
21.2 tonnes is for a fully expended Falcon Heavy.  6.4 tonnes is for full booster and core recovery.

 - Ed Kyle

That is based on FH using F9R 1.1 techniques and RTLS for all three sticks.
FHR using regular side boosters and full thrust center core (as Ms Shotwell alluded will be done) and the side boosters RTLS + center first stage ASDS landing we're talking at least 10 ton GEO payload easily.
The massive problem is the center stage ends up with a lot of energy for FH, and the full boostback needs a lot of energy.
More than half of F9R S1 energy is expended with a full boostback (5000 Km/h staging) vs ASDS landing (8000 Km/h staging).

Having a 10 ton GEO capability is more than the market needs today. And RTLS both side boosters and expending the center stage should result in very interesting DeltaV for deep space launches (until Raptor rockets are available), at a price way cheaper than the most powerful Delta IV Heavy configuration.
« Last Edit: 12/26/2015 03:17 AM by macpacheco »
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Offline John Alan

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #229 on: 12/25/2015 10:35 PM »
RTLS will be a rare event only used when payload is light enough to make it doable...  for F9FT...
My guess is the next stage we will see land on LZ-1 will be a side booster off a FH...
Drone ship is gonna get a workout the next 12 months...  ;)

Offline Dante80

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #230 on: 12/25/2015 10:47 PM »
RTLS will be a rare event only used when payload is light enough to make it doable...  for F9FT...
My guess is the next stage we will see land on LZ-1 will be a side booster off a FH...
Drone ship is gonna get a workout the next 12 months...  ;)

I'm wondering if the FT is capable of RTLS in CRS missions.

Offline Mader Levap

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #231 on: 12/26/2015 12:35 AM »
RTLS will be a rare event only used when payload is light enough to make it doable.
I had impression that it is opposite: that launches requestiong barge will be exception than rule (for example, middle core of FH).

If this impression is right, CRS launches should be eligible for RTLS.
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Offline okan170

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #232 on: 12/26/2015 01:50 AM »
RTLS will be a rare event only used when payload is light enough to make it doable.
I had impression that it is opposite: that launches requestiong barge will be exception than rule (for example, middle core of FH).

If this impression is right, CRS launches should be eligible for RTLS.

Last I read, the FT upgrade was to be instrumental in allowing more flights to do the full RTLS.  Especially since Dragon flights aren't the heaviest F9 can lift, it seems that there are pretty good odds that the CRS missions can do RTLS.

Offline OxCartMark

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #233 on: 12/26/2015 02:27 AM »
I'm flabergasted by the performance loss due to RTLS

Good post.  I agree with most of what you say.  The performance loss is large and was expected due to the tasks being performed being right on the edge of what's possible (both launching a decent payload to orbital velocity and reversing direction so greatly).  But it goes back to one of those key points that Elon keeps repeating - the fuel to do this costs somewhere around $200,000 so if the price is that you double the fuel consumption for a given load that's trivial compared to the cost of having an accident and losing your first stage.  And similarly, his strategy is that if reuse works then its more economical to use a FH-r to launch a load than to use a F9 if the load is at the upper end of the F9s range and would cause the F9 to be irretrievably lost.

Offline John Alan

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #234 on: 12/26/2015 04:52 AM »
My opinion...  ;)
OB-2 was a light load going to a medium LEO...
SX promised to put 11 more up to finish the contract... job done...  8)
Just so happened it was perfect opportunity to "break in" LZ-1 with a RTLS...

A CRS mission with RTLS... no way... Dragon weighs too much...  ???
Looking at the manifest... next year out...
Name one other mission that S2 can push to target orbit from 5000 km/h...  :o
I don't see one... most are sized to use the obsolete 1.1's available payload and target specs...

F9FT update only 'bought' enough performance to turn most missions into drone ship landings...  ???
If anything on CRS... it bought more margin for engine out, higher payloads, Dragon2...
I'll bet Dragon2 is a heavy SOB once it flies...  :P

As the numbers up above and elsewhere point out...
It does not take that much RP1/LOX to get to the drone ship...
That boost back burn takes a lot of energy to 'turn this ship around'...  :P

I also think... they really needed to show they could hit the target on a RTLS...
From day 1... The plans of LZ-1 with 5 pads only mean't one thing to me...
The exact thing they have shown in the FH YouTube video...
Put 2 or 3 cores down there at the same time...  8)
It was silly that the Gov said "one core, no more"...  >:(


Like I said before... The drone ships will get a workout during the next year...  8)

« Last Edit: 12/26/2015 05:17 AM by John Alan »

Offline macpacheco

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #235 on: 12/26/2015 05:15 AM »
My opinion...  ;)
OB-2 was a light load going to a medium LEO...
SX promised to put 11 more up to finish the contract... job done...  8)
Just so happened it was perfect opportunity to "break in" LZ-1 with a RTLS...

A CRS mission with RTLS... no way... Dragon weighs too much...  ???
Looking at the manifest... next year out...
Name one other mission that S2 can push to target orbit from 5000 km/h...  :o
I don't see one... most are sized to use the obsolete 1.1's available payload and target specs...

F9FT update only 'bought' enough performance to turn most missions into drone ship landings...  ???

As the numbers up above and elsewhere point out...
It does not take that much RP1/LOX to get to the drone ship...
That boost back burn takes a lot of energy to 'turn this ship around'...  :P

I also think... they really needed to show they could hit the target on a RTLS...
From day 1... The plans of LZ-1 with 5 pads only mean't one thing to me...
The exact thing they have shown in the FH YouTube video...
Put 2 or 3 cores down there at the same time...  8)
It was silly that the Gov said "one core, no more"...  >:(


Like I said before... The drone ships will get a workout during the next year...  8)

F9R was quoted to handle a 13.1 ton payload to LEO in expendable mode.
Assuming full thrust has 33% more performance, that would be 17 tons to LEO. Of course the target Dragon insertion orbit is slightly higher than a bare bones LEO orbit, but very slightly so.
A fully loaded dragon is 7.5 tons (from wikipedia 4.2 dry + 3.3 payload).
That's just 44% of estimated expendable payload capacity.
Plus in most missions dragon is volume limited. Let's assume 1 ton of cargo less than capacity, or 6.5 tons.
In that scenario we're talking 38% of expendable performance.

A fully loaded dragon is certainly borderline to the limit of RTLS, but I think it can be done. But in most typical Dragon to ISS missions, I think will be done with some margins.

At the same time, F9R missions showed a crescendo of performance. From the fairly easy MDA Corp mission, CRS missions, and increasingly higher GEO missions, SpaceX pushed F9R higher and higher, but with full thrust the next stop is SES-9 with a substantial 5.3 ton launch to GTO, that should demand a very high % of the full performance of the vehicle. So it looks like by the time the first CRS mission comes around, the next step will be 100% performance.
« Last Edit: 12/26/2015 05:24 AM by macpacheco »
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Offline John Alan

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #236 on: 12/26/2015 05:27 AM »
My opinion...  ;)
OB-2 was a light load going to a medium LEO...
SX promised to put 11 more up to finish the contract... job done...  8)
Just so happened it was perfect opportunity to "break in" LZ-1 with a RTLS...

A CRS mission with RTLS... no way... Dragon weighs too much...  ???
Looking at the manifest... next year out...
Name one other mission that S2 can push to target orbit from 5000 km/h...  :o
I don't see one... most are sized to use the obsolete 1.1's available payload and target specs...

F9FT update only 'bought' enough performance to turn most missions into drone ship landings...  ???

As the numbers up above and elsewhere point out...
It does not take that much RP1/LOX to get to the drone ship...
That boost back burn takes a lot of energy to 'turn this ship around'...  :P

I also think... they really needed to show they could hit the target on a RTLS...
From day 1... The plans of LZ-1 with 5 pads only mean't one thing to me...
The exact thing they have shown in the FH YouTube video...
Put 2 or 3 cores down there at the same time...  8)
It was silly that the Gov said "one core, no more"...  >:(


Like I said before... The drone ships will get a workout during the next year...  8)

F9R was quoted to handle a 13.1 ton payload to LEO in expendable mode.
Assuming full thrust has 33% more performance, that would be 17 tons to LEO. Of course the target Dragon insertion orbit is slightly higher than a bare bones LEO orbit, but very slightly so.
A fully loaded dragon is 7.5 tons (from wikipedia 4.2 dry + 3.3 payload).
That's just 44% of estimated expendable payload capacity.
Plus in most missions dragon is volume limited. Let's assume 1 ton of cargo less than capacity, or 6.5 tons.
In that scenario we're talking 38% of expendable performance.

A fully loaded dragon is certainly borderline to the limit of RTLS, but I think it can be done. But in most typical Dragon to ISS missions, I think will be done with some margins.

What about Dragon 2... the unit SpaceX have indicated they will have both cargo and crew versions down the road...
We don't know yet what it weighs dry... do we...  :-\
But SpaceX does...
Would not surprise me if dry it's 6+tons and full load 10+tons fuel and payload...
No way S2 can put that to ISS from 5000km/h... in my opinion...  ;)
« Last Edit: 12/26/2015 05:44 AM by John Alan »

Offline macpacheco

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #237 on: 12/26/2015 05:49 AM »
What about Dragon 2... the unit SpaceX have indicated they will have both cargo and crew versions down the road...
We don't know yet what it weighs dry... do we...  :-\
But SpaceX does...
Would not surprise me if dry it's 7+tons and full load 12+tons fuel and payload...
No way S2 can put that to ISS from 5000km/h... in my opinion...  ;)
Dragon 2 empty weight will be heavier than Dragon 1, but the payloads are likely to be much lighter (NASA is planning on 3 or 4 people launches, with their luggage only as cargo, I assume equivalent to current Soyuz missions), so it might end up being equivalent to a fully loaded Dragon 1. Time will tell. That's two years into the future, so it shouldn't take too long until Raptor rockets are available, then the whole ballgame changes, by then it will make more sense to have a much larger combined people+cargo vehicle with the same capabilities to typical shuttle to ISS missions.

I also think recovering first stages will show quite a few over engineered aspects that can be slimmed down on the first stage.
Those that assume SpaceX will find under engineered aspects for reuse are assuming SpaceX isn't as competent as they have demonstrated over the years.
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Offline SVBarnard

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #238 on: 12/26/2015 05:55 AM »
Hey guys the BA 330 weighs 43,000 lb would it be possible to launch this to LEO as this is where BA wants to put it no? And still recover all three boosters? Or would the core have to be expended? Gosh I hope the answer is yes...

Offline John Alan

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Re: SpaceX Falcon 9 First Landing Discussion--Historic!
« Reply #239 on: 12/26/2015 06:06 AM »
Hey guys the BA 330 weighs 43,000 lb would it be possible to launch this to LEO as this is where BA wants to put it no? And still recover all three boosters? Or would the core have to be expended? Gosh I hope the answer is yes...

As best as I can tell... Boosters to LZ-1 and Core to a Drone ship well downrange should put 43000 lbs to LEO on a FH...
I may be in error on that however...  ;)

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