Author Topic: General Falcon and Dragon discussion (Thread 13)  (Read 215483 times)

Offline Lars-J

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #20 on: 01/02/2016 12:43 AM »

They are definitely going to need more robust coatings for short turnarounds.

Matthew
Why? Do you have any solid evidence that the coating as-is right now make flight impossible for that stage?

No, but having a rougher surface does impact the performance slightly (increased air friction) in the first part of the flight. The top paint layer also protects the stage against the elements while waiting to be launched (corrosion and more). So at some point it will need to be re-applied, and it would be in their interest to have a top layer paint that requires less maintenance.

Offline matthewkantar

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #21 on: 01/02/2016 01:04 AM »
I didn't say anything about possible or impossible. If that much paint is bubbled, missing or pitted on one flight, I'd guess that another flight would result in much greater losses. The coatings on the vehicle are there for a variety of reasons, having them endure more than one flight is important if the goal is to refly in a couple of days.


Matthew

Offline cscott

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #22 on: 01/02/2016 01:12 AM »
It's a good day when rocket reusability has come down to a matter of painting the rocket better.

Offline AncientU

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #23 on: 01/02/2016 01:28 AM »
'Ready to be fired' means tanks have integrity(which was also demo'd by propulsive landing), and valves, pumps, engines all survived in working order -- which is amazing if it is taken at face value.  I'm curious how the wiring, sensors, and electronics fared... especially in the octoweb area.

Multi-use paint probably wasn't on the top ten list of critical systems, but it may be now.
« Last Edit: 01/02/2016 01:28 AM by AncientU »
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Offline AncientU

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #24 on: 01/02/2016 01:37 AM »
The top defect on the interstage looks like paint bubbling off of plain old rust.  Surely that can't be right.  Maybe some flexing?  Aero forces?

The overall impression is of a vehicle that has endured hard use in a brutal flight regime.  We saw what it did to Shuttle and the SRBs but this is the first time anyone has had the opportunity to examine a used, intact first stage booster.

The interstage is composite material, so no rust (hopefully).
I'm not sure what you see that indicates hard use in a brutal flight regime
Looks mostly like soot to me... let's call it post-flight patina.
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Online oiorionsbelt

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #25 on: 01/02/2016 02:18 AM »
There's a lot of rocket that isn't in the picture, wonder how it looks?

Offline clongton

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #26 on: 01/02/2016 11:12 AM »
The top defect on the interstage looks like paint bubbling off of plain old rust.  Surely that can't be right.  Maybe some flexing?  Aero forces?

The overall impression is of a vehicle that has endured hard use in a brutal flight regime.  We saw what it did to Shuttle and the SRBs but this is the first time anyone has had the opportunity to examine a used, intact first stage booster.

The interstage is composite material, so no rust (hopefully).
I'm not sure what you see that indicates hard use in a brutal flight regime
Looks mostly like soot to me... let's call it post-flight patina.

It's a pretty good day when post flight examination turns up nothing more exciting than soot coatings.
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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #27 on: 01/02/2016 11:54 AM »
....

The fact they said there was no damage was a bit astonishing. Could they have done such a thorough analysis of all the structures and internal parts in just under two weeks?

Well, they did say it is OK to be "fired" again. Not "launched". I can see them checking the parts of the engines subject to wear in two weeks since they are so familiar with them and have fired and tested engines many times.
However readiness for flight is quite different and not mentioned yet. Full structural testing and/or disassembly should be needed which we all doubt can be done in such short time.

The whole and entire point of the SpaceX Falcon architecture is to be able to launch these rockets over and over again without requiring a full teardown of the stage and its engines.  "Gas and go" is the goal for this architecture.

It's long been recognized that the need to do such a teardown of the RS-25's after each Shuttle flight guaranteed that STS would never be a low-cost reusable system.  Musk took that as a Lesson Learned.  This system is not designed to require the kind of disassembly you suggest.

We are all well aware of the "gas and go" end goal.

What I meant was that disassembly will be needed (initially) in order to fully understand how the structure of the rocket fared a launch-landing cycle.

Multiple engine firing could be and was tested on the ground many times, so I guess they have pretty good idea what to expect from the engines after 20 or even 40 firings..

What they had no way of knowing is how the structure/materials will bare a reentry and landing. So to check for slacks and cracks they will need disassembly, but they did not yet had time to do it.

Hence I made the suggestion that the mere 10 days they've had so far are quite enough to make sure they can fire, but launching is quite a different animal.. 


Offline Okie_Steve

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #28 on: 01/02/2016 01:38 PM »
Multiple engine firing could be and was tested on the ground many times, so I guess they have pretty good idea what to expect from the engines after 20 or even 40 firings..
One of my Engineering Professors had a saying "Some numbers are better than no numbers" It's an interesting question if a Full duration firing on the ground and an actual flight with acceleration, in flight harmonics and decreasing pressure do in fact produce the same conditions/wear on the engines. Now they can find out for sure. I'd wager that not all of those flight engines are going to stay in that stage.

Offline llanitedave

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #29 on: 01/02/2016 02:22 PM »
There's a lot of rocket that isn't in the picture, wonder how it looks?


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Offline Dante80

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #30 on: 01/02/2016 02:39 PM »
Gas 'n' go is the end goal. To reach that, a lot of returned cores are going to get a CSI:McGregor treatment in the hands of their creator.

The data obtained will serve to provide the next iterations in the Falcon architecture.

The first news coming from SX are positive. Saying that the stage looks good enough to fire statically means that they have plugged it in to check the electronics, the telemetry and the health of many components. It also means that they are confident enough with the structure and the engines to go for a static fire.

From what we understand, this stage will not be disassembled before it is fired again. It will stay at the Cape until that happens.
« Last Edit: 01/02/2016 02:39 PM by Dante80 »

Online guckyfan

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #31 on: 01/02/2016 03:38 PM »
They must be confident enough. They really don't want that much needed pad engulfed in a big fireball. Commercial crew depends on it.

Offline AncientU

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #32 on: 01/03/2016 01:56 AM »
Gas 'n' go is the end goal. To reach that, a lot of returned cores are going to get a CSI:McGregor treatment in the hands of their creator.

The data obtained will serve to provide the next iterations in the Falcon architecture.

The first news coming from SX are positive. Saying that the stage looks good enough to fire statically means that they have plugged it in to check the electronics, the telemetry and the health of many components. It also means that they are confident enough with the structure and the engines to go for a static fire.

From what we understand, this stage will not be disassembled before it is fired again. It will stay at the Cape until that happens.

I suspect that at least one core will go to McGregor for full load testing as they have done on various core/tankage upgrades.  That's a go-no go test, but I think they are confident enough to settle for it... wouldn't be taking a flown core to 39A for cryo-fueling system shakedown and static firing if they weren't fairly confident in their design. 

Could be that getting the core back on the ground without an explosion was the toughest nut to crack. 
It was no small feat.
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Offline macpacheco

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #33 on: 01/03/2016 03:55 AM »
Gas 'n' go is the end goal. To reach that, a lot of returned cores are going to get a CSI:McGregor treatment in the hands of their creator.

The data obtained will serve to provide the next iterations in the Falcon architecture.

The first news coming from SX are positive. Saying that the stage looks good enough to fire statically means that they have plugged it in to check the electronics, the telemetry and the health of many components. It also means that they are confident enough with the structure and the engines to go for a static fire.

From what we understand, this stage will not be disassembled before it is fired again. It will stay at the Cape until that happens.

Gas n' go is a long term goal, which is very unlikely to be achieved with F9R generation rockets.
Gas n' go is of very limited use without 2nd stage reuse.
There isn't much of a scenario where there are enough launches to use the 2 Florida pads even for one launch every week each. And then there's the nagging problem of monopolizing the range while ULA needs to do their launches too.
That's 12 launches in just 6 weeks.

But if you want to obsess, continue obsessing... Sorry to bring some realism to the discussion. Can't help it.

The first huge barrier is eliminating static fires at least for re launches. Actually the barrier is eliminating human review of static fire data. If everything could be computer analysed, perhaps the static fire could be done just before the launch.
« Last Edit: 01/03/2016 03:57 AM by macpacheco »
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Offline meekGee

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #34 on: 01/03/2016 05:11 AM »
Gas 'n' go is the end goal. To reach that, a lot of returned cores are going to get a CSI:McGregor treatment in the hands of their creator.

The data obtained will serve to provide the next iterations in the Falcon architecture.

The first news coming from SX are positive. Saying that the stage looks good enough to fire statically means that they have plugged it in to check the electronics, the telemetry and the health of many components. It also means that they are confident enough with the structure and the engines to go for a static fire.

From what we understand, this stage will not be disassembled before it is fired again. It will stay at the Cape until that happens.

Gas n' go is a long term goal, which is very unlikely to be achieved with F9R generation rockets.
Gas n' go is of very limited use without 2nd stage reuse.
There isn't much of a scenario where there are enough launches to use the 2 Florida pads even for one launch every week each. And then there's the nagging problem of monopolizing the range while ULA needs to do their launches too.
That's 12 launches in just 6 weeks.

But if you want to obsess, continue obsessing... Sorry to bring some realism to the discussion. Can't help it.

The first huge barrier is eliminating static fires at least for re launches. Actually the barrier is eliminating human review of static fire data. If everything could be computer analysed, perhaps the static fire could be done just before the launch.

I know it is against common wisdom, but I don't see the static fires going away.

Today there are two burns - acceptance at McGregor, and still another static fire on the pad.  And then there are the real-time hold-down tests.

I think the one that's going away is the acceptance burn - since it will be replaced by the previous flight that just landed.

A static fire is simple common sense, since it takes place when you know that no further events happen to the core between the test and the launch.

What I think will happen is that static fires won't happen 3 days early, but maybe a few hours: Fire, analyze, ok, launch.

You could say that the hold-down tests are good enough, but there are two issues with this:  First, you don't get to see the shut-down transients, and second, you have very little time to figure it out.    Suppose you want to take a second look at something.  If it's the hold-down scenario, then you miss the launch window.  If it's a static fire, then no problem.

So the key here is to turn-around after the static fire in a matter of hours/minutes, not days.
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Offline Dante80

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #35 on: 01/03/2016 08:34 AM »
Gas n' go is a long term goal, which is very unlikely to be achieved with F9R generation rockets.
Gas n' go is of very limited use without 2nd stage reuse.
There isn't much of a scenario where there are enough launches to use the 2 Florida pads even for one launch every week each. And then there's the nagging problem of monopolizing the range while ULA needs to do their launches too.
That's 12 launches in just 6 weeks.

But if you want to obsess, continue obsessing... Sorry to bring some realism to the discussion. Can't help it.

The first huge barrier is eliminating static fires at least for re launches. Actually the barrier is eliminating human review of static fire data. If everything could be computer analysed, perhaps the static fire could be done just before the launch.

I don't know where the "obsessing" part came from. My post was about the fact that the F9-21 core will not leave the cape for disassembly before doing a WDR/static fire. As well as that to reach the goal SpaceX has set, they will have to check a lot of cores and do iterations to the vehicle.

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #36 on: 01/03/2016 09:22 AM »
If it's the hold-down scenario, then you miss the launch window.  If it's a static fire, then no problem.

So the key here is to turn-around after the static fire in a matter of hours/minutes, not days.

If they are better than 80% confident it will launch they can chance the hold down. That would not come immediately but may well come sooner than expected. They may chose a separate static fire for interplanetary probes and flights to the ISS where a lot is involved in delays.

Offline meekGee

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #37 on: 01/03/2016 11:58 AM »
If it's the hold-down scenario, then you miss the launch window.  If it's a static fire, then no problem.

So the key here is to turn-around after the static fire in a matter of hours/minutes, not days.

If they are better than 80% confident it will launch they can chance the hold down. That would not come immediately but may well come sooner than expected. They may chose a separate static fire for interplanetary probes and flights to the ISS where a lot is involved in delays.
That was not the only consideration....

I don't see why a static fire is an impediment to fast turn around of let's say once per day.   I do see a reliability benefit.

When you get to truly land-gas-go, multiple times per day, then sure.

In the meanwhile, it is not the what's holding them back, IMO.  With a reusable rocket, it should add 15 minutes or less to the cycle time.
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Offline meekGee

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #38 on: 01/03/2016 12:15 PM »
I'll put it differently...

As long as it takes 3 days to recover from a static fire, the impediment to one day turn-around is not the existence of the static fire, but the fact that even from a lowly static fire you still need 3 days...

And conversely, if the rocket can be fully turned around in a day, then surely it can do static fires almost at will...
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Offline Dante2121

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Re: General Falcon and Dragon discussion (Thread 13)
« Reply #39 on: 01/03/2016 01:21 PM »
I'll put it differently...

As long as it takes 3 days to recover from a static fire, the impediment to one day turn-around is not the existence of the static fire, but the fact that even from a lowly static fire you still need 3 days...

And conversely, if the rocket can be fully turned around in a day, then surely it can do static fires almost at will...

You don't actually need one day stage turn around to fly once a day.   I can easily envision a scenario where spacex has a fleet of 7+ first stages and launches one per day.  This gives them a week to turn around each stage, while still maintaining a daily launch cadence. 

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