SpaceX Falcon 9 : GovSat-1 (SES-16) : Jan 31. 2018 - Discussion

[pb2000]

If they filled the RP-1 tank to the max and had just enough LOX to get down...

Rockets always basically filled to 100% no matter what the payload mass is

Makes sense on a normal rocket to have as much margin as possible, but do you know for sure if this applies to the F9? The second stage can obviously dump it's excess fuel after the deorbit burn, but the first stage brings it home - seems like a bad idea if things go pear shaped.

[envy887]

A few things on the configuration of B1032.2 for today's launch:

1. This was planned to be expendable for some time.
2. FH's pending need for the ASDS has nothing to do with B1032.2 being expendable.
3. It has landing legs and grid fins because, while they are expending it, they don't want to just throw a perfectly good test article away without gathering data.
4. This is being treated as a landing to continue to gather data and refine the landing algorithms the F9 computer systems use to land the boosters.

So, that is why the boats are going out.  To receive telemetry vs fairing recovery

Observe/record visual landing behavior?

not visual.  If they are doing #4, then to gather data they need a receiver near by since the Cape would be below the visual horizon to receive the telemetry.

We've seen boats come back with fairing parts, so they probably are doing both.

[lrk]

If they filled the RP-1 tank to the max and had just enough LOX to get down...

Rockets always basically filled to 100% no matter what the payload mass is

Makes sense on a normal rocket to have as much margin as possible, but do you know for sure if this applies to the F9? The second stage can obviously dump it's excess fuel after the deorbit burn, but the first stage brings it home - seems like a bad idea if things go pear shaped.

F9 S1 can always use any extra fuel for a less-efficient but more gentle entry and landing. 

[starsilk]

If they filled the RP-1 tank to the max and had just enough LOX to get down...

Rockets always basically filled to 100% no matter what the payload mass is

Makes sense on a normal rocket to have as much margin as possible, but do you know for sure if this applies to the F9? The second stage can obviously dump it's excess fuel after the deorbit burn, but the first stage brings it home - seems like a bad idea if things go pear shaped.

first stage always burns to depletion (leave enough for landing only). that gives the second stage the most margin possible in case it needs it.

[RocketLover0119]

Scrub for the day due to winds, next try tomorrow.   

[Prettz]

Hi, I'm here from China Aero Space Technology corp[1] and I want to bid on those scrap legs...

1 - made up name.

Cured carbon fiber has very limited uses and a very low scrap value.

Obviously not selling the whole legs, that would be full of IP. The legs have a quite a bit of metal on them, though (the pneumatics, for instance) that would fetch an amount more than 0.

If it wouldn't get enough to make up for the cost of tearing apart the legs, that would be a very good reason not to bother scrapping them.

But we know why they're leaving them on now, and the test data is certainly worth more than the scrap value.

[pb2000]

If they filled the RP-1 tank to the max and had just enough LOX to get down...

Rockets always basically filled to 100% no matter what the payload mass is

Makes sense on a normal rocket to have as much margin as possible, but do you know for sure if this applies to the F9? The second stage can obviously dump it's excess fuel after the deorbit burn, but the first stage brings it home - seems like a bad idea if things go pear shaped.

F9 S1 can always use any extra fuel for a less-efficient but more gentle entry and landing.

The mission I'm specifically thinking of was formosat - the payload was tiny and it landed on the drone ship downrange. I'll go back and re-watch that mission, but I don't recall any sort of excessively long post sep burns.

[Jim]

If they filled the RP-1 tank to the max and had just enough LOX to get down...

Rockets always basically filled to 100% no matter what the payload mass is

Makes sense on a normal rocket to have as much margin as possible, but do you know for sure if this applies to the F9? The second stage can obviously dump it's excess fuel after the deorbit burn, but the first stage brings it home - seems like a bad idea if things go pear shaped.

first stage always burns to depletion (leave enough for landing only). that gives the second stage the most margin possible in case it needs it.

If first stages were to be partially loaded, then many different load cases come into effect, like liftoff lighter load.  And then there is slosh at a different point in the flight.
A lot more analysis would need to be done to cover all the new cases.  And some might have design impacts.

[llanitedave]

If they filled the RP-1 tank to the max and had just enough LOX to get down...

Rockets always basically filled to 100% no matter what the payload mass is

Makes sense on a normal rocket to have as much margin as possible, but do you know for sure if this applies to the F9? The second stage can obviously dump it's excess fuel after the deorbit burn, but the first stage brings it home - seems like a bad idea if things go pear shaped.

F9 S1 can always use any extra fuel for a less-efficient but more gentle entry and landing.

The mission I'm specifically thinking of was formosat - the payload was tiny and it landed on the drone ship downrange. I'll go back and re-watch that mission, but I don't recall any sort of excessively long post sep burns.

They also need to keep extra margin on board in case of an engine out.  There are a number of engine failure scenarios that could still make orbit but would require the entire fuel margins leaving nothing left for return.

[Bubbinski]

Seeing some chatter elsewhere (Spaceflight Now, Twitter) about the scrub. Besides winds, the team apparently is replacing a sensor on the 2nd stage, rocket will go horizontal.

[Boost]

Probably both the sensor and the high altitude winds. What is the forecast about those winds for tomorrow ?

[RocketLover0119]

I believe it is 90℅ GO.

Probably both the sensor and the high altitude winds. What is the forecast about those winds for tomorrow ?

[Boost]

But these 90% exclude the high altitude winds isn't it ?

[RocketLover0119]

Oh... Forgot about that, yeah they exclude them, that GO is everything else weather related.

But these 90% exclude the high altitude winds isn't it ?

[Elthiryel]

Upper level winds tomorrow are forecasted to be at 100 knots (110 today).

But it seems that today they were monitoring ground winds, according to James Dean, and this was the main issue and the reason behind the first delay (before the sensor failure was discovered, obviously). Tomorrow thick cloud layers are predicted to be the biggest concern.

[Jim]

But these 90% exclude the high altitude winds isn't it ?

Correct.  Winds aloft is not part of weather constraints.  The vehicle contractor makes that call.

[intrepidpursuit]

Here's hoping they post high res versions of those F9 FH shots. That's an incredible milestone to see.

[mlindner]

FEATURE ARTICLE: SpaceX set to loft GovSat-1 via Falcon 9 launch -
https://www.nasaspaceflight.com/2018/01/spacex-govsat-1-falcon-9-launch/

- By William Graham

And yes, that's Zuma's F9 in the lead photo for now as we're waiting for pad photos. Will replace when we have new ones. Media pad photos delayed due to the late arrival of the Luxembourg royal family.

(Pfft, that always happens. )

>  As with December’s Iridium-NEXT launch, SpaceX will dispose of the older Block 3 booster by flying it in an expendable configuration without landing legs.

It has lending legs.

[Jet Black]

That probably adds up to a very hot reentry and three engine landing burn -- stretching the envelope for down range landings after high energy payload deliveries.

or other corner cases to test stresses on the vehicle, for example intentionally bringing it in at shallower angles to improve range and so on. Although  they are pretty good at landing rockets now, there is always new stuff to learn.

If they aren't going to use that rocket again, then information and data are more valuable than the remains of the vehicle sitting at the bottom of the sea.

[ATPTourFan]

SpaceX has been working on using more of the atmosphere to slow down Falcon 9 as that saves propellant and will be important for BFR.

Wouldn’t be surprised if they use these opportunities to test aggressive entries where a loss of booster on the way down wouldn’t be a problem.

Either way, SpaceX knows what they are doing and I trust they had many smart people develop the flight plan for this secondary phase of today’s mission. We need not worry if the truth isn’t immediately obvious.