SpaceX F9 : SES-10 with reuse of CRS-8 Booster SN/1021 : 2017-03-30 : DISCUSSION

[Lars-J]

Comparing press kits...

Echostar-23 MECO @ 2:43
SES-10 MECO @ 2:38

 

No wonder SpaceX said they would give SES some pieces of this booster.... 

We already knew that they were going to attempt recovery/landing of this booster (again), so the earlier MECO time should not be a surprise. Some F9 flights have had MECO as early as ~2:30 (RTLS missions).

[Toast]

Comparing press kits...

Echostar-23 MECO @ 2:43
SES-10 MECO @ 2:38

 

No wonder SpaceX said they would give SES some pieces of this booster.... 

We already knew that they were going to attempt recovery/landing of this booster (again), so the earlier MECO time should not be a surprise. Some F9 flights have had MECO as early as ~2:30 (RTLS missions).

Since Echostar-23 was an expendable launch, I think the implication was that MECO time was late, not early. Unless the throttle profile is different, five seconds is a really tight margin.

[Req]

Water tower on the left, RSS on the right. Couldn't see a stage with that method anyway as it would be blocked by the RSS. See here: https://gfycat.com/HoarseFriendlyArcticwolf

This stack even without it's payload was well-lit and clearly visible the morning before the static fire.  I was watching the stream so I saw it, and Flying Beaver posted a screengrab from his phone, which I have attached, in the updates thread here:

https://forum.nasaspaceflight.com/index.php?topic=42544.msg1658921#msg1658921

Edit: I also remember seeing what looked like rotating emergency/caution/etc lights on a vehicle for quite a while before it went upright.

[Lars-J]

Since Echostar-23 was an expendable launch, I think the implication was that MECO time was late, not early. Unless the throttle profile is different, five seconds is a really tight margin.

I see... But 9 engines burning for 5 seconds at full thrust is a LOT of propellant. Enough for a 45 second landing burn at full thrust.

[stcks]

Since Echostar-23 was an expendable launch, I think the implication was that MECO time was late, not early. Unless the throttle profile is different, five seconds is a really tight margin.

I see... But 9 engines burning for 5 seconds at full thrust is a LOT of propellant. Enough for a 45 second landing burn at full thrust.

Where's your re-entry burn then? Need a 3 engine re-entry burn and a landing burn. Its going to be tight, not saying they can't do it, but its coming in hot.

[Lars-J]

Since Echostar-23 was an expendable launch, I think the implication was that MECO time was late, not early. Unless the throttle profile is different, five seconds is a really tight margin.

I see... But 9 engines burning for 5 seconds at full thrust is a LOT of propellant. Enough for a 45 second landing burn at full thrust.

Where's your re-entry burn then? Need a 3 engine re-entry burn and a landing burn. Its going to be tight, not saying they can't do it, but its coming in hot.

That was just an example to illustrate how much longer the propellant can last for one engine instead of nine. Here is what the burn durations were for the last droneship landing:
 - braking burn: 15 seconds (3 engines)
 - landing burn: 30 seconds (1 engine)

Assuming those burns where at full thrust, that is ~8.3 seconds worth of propellant for all nine engines. Not a lot.

[stcks]

Since Echostar-23 was an expendable launch, I think the implication was that MECO time was late, not early. Unless the throttle profile is different, five seconds is a really tight margin.

I see... But 9 engines burning for 5 seconds at full thrust is a LOT of propellant. Enough for a 45 second landing burn at full thrust.

Where's your re-entry burn then? Need a 3 engine re-entry burn and a landing burn. Its going to be tight, not saying they can't do it, but its coming in hot.

That was just an example to illustrate how much longer the propellant can last for one engine instead of nine. Here is what the burn durations were for the last droneship landing:
 - braking burn: 15 seconds (3 engines)
 - landing burn: 30 seconds (1 engine)

Assuming those burns where at full thrust, that is ~8.3 seconds worth of propellant for all nine engines. Not a lot.

Yeah and a different trajectory and/or throttle profile is likely the difference. 45 total engine seconds is probably not enough to make it down in one piece, but around 75 or so should be doable.

[king1999]

Comparing press kits...

Echostar-23 MECO @ 2:43
SES-10 MECO @ 2:38

 

No wonder SpaceX said they would give SES some pieces of this booster.... 

We already knew that they were going to attempt recovery/landing of this booster (again), so the earlier MECO time should not be a surprise. Some F9 flights have had MECO as early as ~2:30 (RTLS missions).

Since Echostar-23 was an expendable launch, I think the implication was that MECO time was late, not early. Unless the throttle profile is different, five seconds is a really tight margin.

Echostar-23 MECO @ 2:43 doesn't mean it used up all fuel at that moment. It must have some margin to recover from one or two engine failure. Thus the margin for SES-10 should be more than 5 seconds.

[Lars-J]

That was just an example to illustrate how much longer the propellant can last for one engine instead of nine. Here is what the burn durations were for the last droneship landing:
 - braking burn: 15 seconds (3 engines)
 - landing burn: 30 seconds (1 engine)

Assuming those burns where at full thrust, that is ~8.3 seconds worth of propellant for all nine engines. Not a lot.

Yeah and a different trajectory and/or throttle profile is likely the difference. 45 total engine seconds is probably not enough to make it down in one piece, but around 75 or so should be doable.

Do you have any numbers to back that '75 seconds' up? A whole 30 seconds more??? And different compared to what - do you expect this to be radically different than previous downrange landings. If so, show some data from earlier flights.

 I don't think most realize how much difference just a few seconds of thrust makes when the stage is nearly empty.

[stcks]

That was just an example to illustrate how much longer the propellant can last for one engine instead of nine. Here is what the burn durations were for the last droneship landing:
 - braking burn: 15 seconds (3 engines)
 - landing burn: 30 seconds (1 engine)

Assuming those burns where at full thrust, that is ~8.3 seconds worth of propellant for all nine engines. Not a lot.

Yeah and a different trajectory and/or throttle profile is likely the difference. 45 total engine seconds is probably not enough to make it down in one piece, but around 75 or so should be doable.

Do you have any numbers to back that '75 seconds' up? A whole 30 seconds more??? And different compared to what - do you expect this to be radically different than previous downrange landings. If so, show some data from earlier flights.

 I don't think most realize how much difference just a few seconds of thrust makes when the stage is nearly empty.

I'm not sure how you are misunderstanding me, but yes I fully understand this. Please go back and read what I have written.

Lets go through this again, using YOUR example:

15 second 3 engine braking burn == 45 engine seconds
30 second 1 engine landing burn == 30 engine seconds
45+30 = 75 engine seconds

[manoweb]

You cannot take single engine performance and just multiply - that does not take gravity losses into account!

[shooter6947]

Won't there be one o' them 3-engine landing burns if the bird is coming in hot on bingo fuel?

And probably a shorter entry burn, too,  accepting a higher heating load from greater aero-deceleration.

[stcks]

Won't there be one o' them 3-engine landing burns if the bird is coming in hot on bingo fuel?

And probably a shorter entry burn, too,  accepting a higher heating load from greater aero-deceleration.

That was really the entire reason that I pointed out that there is only a 5 second difference in first stage burn time between SES-10 and Echostar-23. Then the conversation got a bit derailed  .

To stick this landing, they are very likely going to have a shorter than usual entry burn and some form of 3-engine landing burn (be that 1-3-1 or purely 3). This is a MECO time only matched by the JCSAT-14 mission. All the others (not counting the expendable Echostar-23 obviously) were shorter by at least 2 seconds.

[Kaputnik]

Comparing press kits...

Echostar-23 MECO @ 2:43
SES-10 MECO @ 2:38

 

No wonder SpaceX said they would give SES some pieces of this booster.... 

We already knew that they were going to attempt recovery/landing of this booster (again), so the earlier MECO time should not be a surprise. Some F9 flights have had MECO as early as ~2:30 (RTLS missions).

Since Echostar-23 was an expendable launch, I think the implication was that MECO time was late, not early. Unless the throttle profile is different, five seconds is a really tight margin.

Echostar-23 MECO @ 2:43 doesn't mean it used up all fuel at that moment. It must have some margin to recover from one or two engine failure. Thus the margin for SES-10 should be more than 5 seconds.

SOP for expendable vehicles is to burn first stage to depletion, so any margin is passed on to the second stage to maximise its margins.

[Jakusb]

other than finishing with this quote stating that if all goes well, #1021 will never fly again

Is that really what the quote says?
If the SES boardroom gets a grid fin and a leg, does that mean #1021 will (or could) never fly again?   

There could be several reasons to have core 1021 retire after this flight.
It took them months to refurbish, why take that trouble again when there are improved cores to refly?
Let's assume they just wanted to prove reflight for now. This would be the first core to fly twice, ever. Make it a museum piece.

Of course if SpaceX is confident enough they could relfy more times, but they are working hard on some improvements that should make future cores much more likely to need little to no refurbishment.
Use the data of this core to further that process and do not risk this core any further.

I really do not know what they will do, other then approach it pragmatically as they do with everything they do. They clearly know what they are doing.

Lets first see this core successfully fly again and hopefully also land again safely. That would be a major milestone and historic achievement.

[Jarnis]

I could see them reusing it one more time to fly *another* SES satellite for PR/prestige value of that "stunt" if it is in great shape.

But... unlikely, as they need to move to Block 5 soon or Dragon 2 manned flights will get pushed due to the requirement of flying X flights on a "frozen" config before manned flights.

[toruonu]

Do we know if they got the booster up and if so early enough to still make the original launch time or will there be a slip to 1.04?

[deruch]

I might add that I find it amazing that's there's been almost a deafening silence lately when it comes to the spreadsheet created by Tory Bruno (or at least touted by him) and then vigorously debated on this forum on the cost benefit of reuse.

The true significance of the success of this mission is for SX alone. Musk said that he would have considered them to have failed if LV reuse did not succeed.

Many have forgotten this. He hasn't.

If this mission succeeds, and nothing more comes of it ... SX has, as a venture, succeeded in his opinion.

I wish him and SX well in their accomplishment and reaching the goal they set for themselves.

I'm willing to agree that they see it as a big step forwards, but I don't think this limited type of reuse rises to level of "Mission Accomplished" for Musk/SX.  When Musk made those statements he was at least talking about full reuse, if not a "Fully and Rapidly Reused" LV.  That's clearly still a milestone on their pathway to Mars, it's just been postponed to the ITS architecture instead of the Falcon family (i.e. no 2nd stage reuse for F9/FH).  Booster reuse is just the (not so) low hanging fruit.  The first step.  So, while this launch will hopefully be a great success for SpaceX, no.  They haven't (capital S) Succeeded, yet. 

[Flying Beaver]

The 39A HIF pictured today:

Forground booster is defiantly for NROL-76 (gridfins, etc for LZ-1 landing). The one behind todays flight booster though looks like a landed core that's been stripped down (No dance-floor/engines. With the top of the LOX tank visible of the right). The boosters used for CRS-9 is the only one (publicly) unaccounted for cape-side. Interesting though that it is fully cleaned, and even with the leg locking pin wiring still in place.

Not the Immersat-35E booster, as it is still at McGregor, it should depart there after this evenings launch.

[Paul_G]

https://spaceflightnow.com/2017/03/30/ses-10-mission-status-center/

Next up will be a series of checkouts and software uploads on the SES 10 communications satellite

Why would you wait until the satellite is mated and vertical on the pad before uploading software? Wouldn't it be easier to do this whilst you can stand net to it on the ground, or is the satellite not turned on until the rocket went vertical?

Also, is 13 hours checkout typical for a satellite - what kind of things would be covered here, and would the checkout time be the same if the satellite had been vertically integrated and not rotated 90' plus ?

Thanks

Paul