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

[Ben the Space Brit]

I'm sure that the legs alter the stage's performance, up and down. Maybe they want tracking data that is applicable to flights leading to the recovery of the booster?

[gongora]

Also, interesting fairing design. Doesn't even mention SES.

The satellite is owned by a joint venture of SES and the government of Luxembourg.  When they first ordered it they were calling it SES-16/GovSat, but later the branding seems to have changed to just GovSat-1, even on the SES web site.

[Lar]

Either the expended booster came on such short notice so they left the legs on for more testing, or they want to burn the old legs in advance of block V along with the fins.

In the latter case, why not just sell them for scrap?

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

1 - made up name.

[ChrisGebhardt]

Either the expended booster came on such short notice so they left the legs on for more testing, or they want to burn the old legs in advance of block V along with the fins.

In the latter case, why not just sell them for scrap?

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.

[MechE31]

Either the expended booster came on such short notice so they left the legs on for more testing, or they want to burn the old legs in advance of block V along with the fins.

In the latter case, why not just sell them for scrap?

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

[AncientU]

Either the expended booster came on such short notice so they left the legs on for more testing, or they want to burn the old legs in advance of block V along with the fins.

In the latter case, why not just sell them for scrap?

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.

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.

[intrepidpursuit]

Either the expended booster came on such short notice so they left the legs on for more testing, or they want to burn the old legs in advance of block V along with the fins.

In the latter case, why not just sell them for scrap?

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.

They did a launch on the west coast with fins and no legs. I wonder if it showed enough variance in behavior (likely on the way down) that they decided they get better data with the legs. It may also be true that they already have plenty of block 3/4 legs and so they lose very little by dumping them in the water, any any gain in data quality is worth it.

[Surfdaddy]

Either the expended booster came on such short notice so they left the legs on for more testing, or they want to burn the old legs in advance of block V along with the fins.

In the latter case, why not just sell them for scrap?

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.

They did a launch on the west coast with fins and no legs. I wonder if it showed enough variance in behavior (likely on the way down) that they decided they get better data with the legs. It may also be true that they already have plenty of block 3/4 legs and so they lose very little by dumping them in the water, any any gain in data quality is worth it.

One thing they are clearly very good at is maximizing the value of all assets. They get information, push envelope, etc. on nearly all flights. They are undoubtedly maximizing their data return even with this expendable launch and reentry.

[JonathanD]

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.

It is notable that they have not done this on other expendable launches.  It would be interesting to know why they chose this one and if there is something in particular they are looking for.  It's not like they have a shortage of data from booster landings.

[Elthiryel]

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.

It is notable that they have not done this on other expendable launches.  It would be interesting to know why they chose this one and if there is something in particular they are looking for.  It's not like they have a shortage of data from booster landings.

The other expendable launches were expendable because the satellite was too heavy, so the booster would not have enough fuel to land after stage separation anyway. Since the booster landings became more or less routine, the only exception to date has been the last Iridium flight, when the booster was equipped with grid fins, but not with legs.

[Stefan.Christoff.19]

Maybe they want to find out exactly how much performance is left if they fly in the normal re-use configuration.

[ChrisGebhardt]

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.

It is notable that they have not done this on other expendable launches.  It would be interesting to know why they chose this one and if there is something in particular they are looking for.  It's not like they have a shortage of data from booster landings.

Two flights ago, Iridium NEXT-4 was expended in just this manner (minus the landing legs) with a soft landing in the ocean.

[pb2000]

Either the expended booster came on such short notice so they left the legs on for more testing, or they want to burn the old legs in advance of block V along with the fins.

In the latter case, why not just sell them for scrap?

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.

They did a launch on the west coast with fins and no legs. I wonder if it showed enough variance in behavior (likely on the way down) that they decided they get better data with the legs. It may also be true that they already have plenty of block 3/4 legs and so they lose very little by dumping them in the water, any any gain in data quality is worth it.

If they filled the RP-1 tank to the max and had just enough LOX to get down, would the F9 be bottom heavy enough to be stable in the water or at least tip over slowly enough so as to not RUD? Add an interstage towing adapter and haul'er back into be scrapped. [party thread] Bonus points if Elon rides the rocket back into port wearing a pirate costume or Captain's uniform [/party thread]

[JonathanD]

It may also be true that they already have plenty of block 3/4 legs and so they lose very little by dumping them in the water

How funny is it that only now this seems wasteful because we have become so accustomed to SpaceX reusing boosters and agonizing over things like fairing recovery, when throughout the history of rocketry dumping crap in the ocean was totally normal (and still is, unless you're Chinese, in which case flaming hunks of rocket fall in your garden).

[RDoc]

It may also be true that they already have plenty of block 3/4 legs and so they lose very little by dumping them in the water

How funny is it that only now this seems wasteful because we have become so accustomed to SpaceX reusing boosters and agonizing over things like fairing recovery, when throughout the history of rocketry dumping crap in the ocean was totally normal (and still is, unless you're Chinese, in which case flaming hunks of rocket fall in your garden).

Actually if you live in parts of Russia, they and their fuel fall into the forests and fields around you.

[Jim]

If they filled the RP-1 tank to the max and had just enough LOX to get down,s uniform [/party thread]

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

[Jim]

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

[Space Ghost 1962]

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?

[oiorionsbelt]

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

I believe ChrisG was responding to the 'but it has legs, why?' comments.

[Jim]

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.