SpaceX Falcon 9 - Inmarsat 5 F4 - May 15, 2017 - DISCUSSION

[LouScheffer]

That does not seem like enough.  6100-2437 = 3663 kg.  So burning all propellant at an ISP of 320 implies a total delta-V of 320*9.8*ln(6100/3663) = 1600 m/s.   Assuming the same F9 performance as EchoStar, that's not enough to get into GEO (the lighter Echostar 23 had more than this to go to reach GEO),  much less do any stationkeeping.

So either this is a more powerful F9, or they will need to do final orbit raising electrically.

Well if they are doing a Super-Synchronous GTO and or reducing inclination they could possibly get it down to 1600, right? Also I think the total mass is actually more like 6070kg.

To get to a GEO-1600 orbit from the cape, you need about +350 m/s over a minimal transfer orbit.  The EchoStar 23, about 500 kg lighter, only made it to +200 m/s over minimal GTO.  Raising the mass to 6070 kg would only leave about +20 m/s over minimal GTO.

On the other hand, one of the advantages of the SSTO, compared to inclination reduction, is that it lends itself to minimum residual shutdown.  This is because for SSTO you just blast as much as you can in the direction of the orbit, whereas inclination reduction wants a burn of specific direction and delta-V.  This can be a big deal since the last bit of propellant gives a lot of delta-V.  If we assume the residual fuel is on the order of 1%, or about 1,150 kg, and the stage 4500 kg, and the satellite 6070 kg, then this last percent of fuel would give about 348*9.8*ln((1150+4500+6070)/(4500+6070)) or about 350 m/s more - just about what is needed.

So that's my new prediction - a super-synchronous transfer orbit, with a minimum residual shutdown, and a final deficit of 1600 m/s.  So an inclination of 25-28 degrees, and an apogee of at least 65000 km.

Edit: add apogee and inclination predictions.

[BabaORileyUSA]

That does not seem like enough.  6100-2437 = 3663 kg.  So burning all propellant at an ISP of 320 implies a total delta-V of 320*9.8*ln(6100/3663) = 1600 m/s.   Assuming the same F9 performance as EchoStar, that's not enough to get into GEO (the lighter Echostar 23 had more than this to go to reach GEO),  much less do any stationkeeping.

So either this is a more powerful F9, or they will need to do final orbit raising electrically.

Well if they are doing a Super-Synchronous GTO and or reducing inclination they could possibly get it down to 1600, right? Also I think the total mass is actually more like 6070kg.

To get to a GEO-1600 orbit from the cape, you need about +350 m/s over a minimal transfer orbit.  The EchoStar 23, about 500 kg lighter, only made it to +200 m/s over minimal GTO.  Raising the mass to 6070 kg would only leave about +20 m/s over minimal GTO.

On the other hand, one of the advantages of the SSTO, compared to inclination reduction, is that it lends itself to minimum residual shutdown.  This is because for SSTO you just blast as much as you can in the direction of the orbit, whereas inclination reduction wants a burn of specific direction and delta-V.  This can be a big deal since the last bit of propellant gives a lot of delta-V.  If we assume the residual fuel is on the order of 1%, or about 1,150 kg, and the stage 4500 kg, and the satellite 6070 kg, then this last percent of fuel would give about 348*9.8*ln((1150+4500+6070)/(4500+6070)) or about 350 m/s more - just about what is needed.

So that's my new prediction - a super-synchronous transfer orbit, with a minimum residual shutdown, and a final deficit of 1600 m/s.  So an inclination of 25-28 degrees, and an apogee of at least 65000 km.

Edit: add apogee and inclination predictions.

Apogee Height:  63,520 km; Inclination = 24.6 degrees.

That's not a guess, and not a calculation (that *I* did, anyways!)

Kudos to LouSheffer - you Devil, you!

[abaddon]

I had guessed it would be a burn-to-depletion scenario... but wow, well done @LouScheffer!

[FutureSpaceTourist]

Article for the firing and forward manifest, by Chris Gebhardt:
https://www.nasaspaceflight.com/2017/05/falcon-9-static-fire-1-inmarsat5f4/

Great article as always, thank you.

One possible omission? SpaceX did a 14 day turnaround at LC-40 in Sep 2014 (AsiaSat 6 on the 7th and CRS-4 on the 21st).

[Chris Bergin]

Article for the firing and forward manifest, by Chris Gebhardt:
https://www.nasaspaceflight.com/2017/05/falcon-9-static-fire-1-inmarsat5f4/

Great article as always, thank you.

One possible omission? SpaceX did a 14 day turnaround at LC-40 in Sep 2014 (AsiaSat 6 on the 7th and CRS-4 on the 21st).

I just pictured you typing that with one hand whilst holding a very long spreadsheet printout was in the other hand. (as a compliment). Let me see if I can add that without messing up his article

[ChrisGebhardt]

Article for the firing and forward manifest, by Chris Gebhardt:
https://www.nasaspaceflight.com/2017/05/falcon-9-static-fire-1-inmarsat5f4/

Great article as always, thank you.

One possible omission? SpaceX did a 14 day turnaround at LC-40 in Sep 2014 (AsiaSat 6 on the 7th and CRS-4 on the 21st).

Oh, totally forgot about that!  Thanks for catching that.

[getitdoneinspace]

STATIC FIRE! SpaceX Falcon 9 (Inmarsat 5 F4) has fired up at 39A. Wait for SpaceX tweet (after test data review).

RIGHT ON TIME. I like that. Hopefully a consistent trend while progressing through the increasing launch cadence.

[MattMason]

With all this successful work on 39A, you'd wonder when they'll find time to get the RSS dismantled and CC work applied. I'm sure the answer involves getting SLC 40 online by August, but their flight schedule's pretty aggressive with two active pads.

[mme]

With all this successful work on 39A, you'd wonder when they'll find time to get the RSS dismantled and CC work applied. I'm sure the answer involves getting SLC 40 online by August, but their flight schedule's pretty aggressive with two active pads.

My understanding is that there is no rush to dismantle RSS and it does not interfere with CC work nor even CC missions.

I think they said they are going to mount the CC access arm while making the FH modifications later this year. But I could be misremembering and I'm not sure they even need the access arm for the first CC demo mission.

[rockets4life97]

What I am most impressed by is the schedule fidelity. It seems like SpaceX is coming in on time. They really need to do this regularly to get through the manifest.

[macpacheco]

What I am most impressed by is the schedule fidelity. It seems like SpaceX is coming in on time. They really need to do this regularly to get through the manifest.

Nah, my reading is a launch every two weeks is already less than they can accomplish, time to move to a launch every 10 days (when the range allows for it) and see them always be a day or two behind schedule but beating the a launch every 2 weeks current plan.
But, just perhaps, that will create problems with the range that needs to be prepared for their plans.
It will be interesting anyhow.
Maybe increase the tempo by 24 hrs at a time until they find their sustainable limits.

Or maybe this looked easy because they prepared this booster in parallel with NROL-76 during the 2 week delay.

AKA I really don't know but I would love to know the answer !

[John Alan]

The RSS (I admit) is an ugly eyesore and reminder for what once was... 

BUT...

I seems it's not in the way and for all practical purposes could be left as is... if need be... 

[Dante80]

According to this, the payload adapter that Falcon 9 has is made by RUAG. This is talking about the actual PAF, or a separate adapter?

[Flying Beaver]

According to this, the payload adapter that Falcon 9 has is made by RUAG. This is talking about the actual PAF, or a separate adapter?

Referencing this component i'm sure.

[Dante80]

That was my thought too. Here is the satellite, sitting on the heavy SpaceX PAF variant (the one that is good for ten tons).

[AncientU]

What I am most impressed by is the schedule fidelity. It seems like SpaceX is coming in on time. They really need to do this regularly to get through the manifest.

Nah, my reading is a launch every two weeks is already less than they can accomplish, time to move to a launch every 10 days (when the range allows for it) and see them always be a day or two behind schedule but beating the a launch every 2 weeks current plan.
But, just perhaps, that will create problems with the range that needs to be prepared for their plans.
It will be interesting anyhow.
Maybe increase the tempo by 24 hrs at a time until they find their sustainable limits.

Or maybe this looked easy because they prepared this booster in parallel with NROL-76 during the 2 week delay.

AKA I really don't know but I would love to know the answer !

This bi-weekly tempo from one (relatively new) pad seems to be an achievement of the new TEL design with throwback feature.  Good news is that a similar system is coming on line at LC-40 soon.  TEL hardware of this design is probably also planned for Boca Chica and Vandenberg as schedule allows.  Four pads with quick turn-around capability removes a key constraint on launch cadence.  Likewise, reusable boosters with shorter and shorter refurb times removes the factory throughput constraint.  Finally, SpaceX will remove the static fire requirement at some point which will make weekly launches from a given pad possible.

When launching the constellation in 2019-2020, they'll need 50-100 launches a year just for internal payloads... plus another 25-50 for USG plus commercial customers.  Doesn't seem so impossible any more.

[AncientU]

That was my thought too. Here is the satellite, sitting on the heavy SpaceX PAF variant.

Is the payload adaptor carbon composite, too? 
Does anyone else do that?

[deruch]

This bi-weekly tempo from one (relatively new) pad seems to be an achievement of the new TEL design with throwback feature.  Good news is that a similar system is coming on line at LC-40 soon.  TEL hardware of this design is probably also planned for Boca Chica and Vandenberg as schedule allows.  Four pads with quick turn-around capability removes a key constraint on launch cadence.  Likewise, reusable boosters with shorter and shorter refurb times removes the factory throughput constraint.  Finally, SpaceX will remove the static fire requirement at some point which will make weekly launches from a given pad possible.

Don't forget that they also now have a hangar (at 39A) that allows them to process multiple vehicles at a time.  Unfortunately, that won't translate to SLC-40 when it is back online.

[AncientU]

This bi-weekly tempo from one (relatively new) pad seems to be an achievement of the new TEL design with throwback feature.  Good news is that a similar system is coming on line at LC-40 soon.  TEL hardware of this design is probably also planned for Boca Chica and Vandenberg as schedule allows.  Four pads with quick turn-around capability removes a key constraint on launch cadence.  Likewise, reusable boosters with shorter and shorter refurb times removes the factory throughput constraint.  Finally, SpaceX will remove the static fire requirement at some point which will make weekly launches from a given pad possible.

Don't forget that they also now have a hangar (at 39A) that allows them to process multiple vehicles at a time.  Unfortunately, that won't translate to SLC-40 when it is back online.

Right.
There is the new refurb facility coming on line at the Port, though, which should help with the bigger rework tasks.

[spacenut]

Is this launch going to be webcast?  If so, when?