Author Topic: SpaceX Falcon 9 : Hispasat 30W-6 (1F) : March 6, 2018 - DISCUSSION (Read 164927 times)

Flying Beaver · « **Reply #60 on:** 02/21/2018 04:26 am »

Quote from: cppetrie on 02/21/2018 02:05 am

The radio silence on the static fire combined with no video coverage of the pad by the usual sources is kind of unnerving. The window closes in a little less than 2 hours. $:-\$

I guess we can just hope for a SpaceX tweet within the next hour if they fired at the end of the window. That's of course if their twitter is manned right now, seeing they could be off before getting on-shift for the launch in 15hrs.

Tomness · « **Reply #61 on:** 02/21/2018 04:55 am »

Quote from: FutureSpaceTourist on 02/21/2018 04:47 am

Quote
Static fire test of Falcon 9 complete—targeting February 25 launch of Hispasat 30W-6 from Pad 40 in Florida.

https://twitter.com/spacex/status/966187350740127744

LC-1 this LC-2, SF complete, you are a go.

input~2 · « **Reply #62 on:** 02/21/2018 04:05 pm »

WESTERN NORTH ATLANTIC.
FLORIDA.
1. HAZARDOUS OPERATIONS 250530Z TO 250830Z FEB,
ALTERNATE 260530Z TO 260830Z FEB
IN AREAS BOUND BY:
A. 28-36N 080-38W, 28-38N 080-36W,
28-38N 080-00W, 28-35N 079-30W,
28-33N 079-30W, 28-30N 080-00W,
28-31N 080-36W.
B. 28-27N 075-01W, 28-30N 074-16W,
28-37N 072-06W, 28-17N 071-56W,
27-46N 072-08W, 27-50N 073-10W,
28-21N 074-58W.
2. CANCEL THIS MSG 260930Z FEB 18.//

Authority: EASTERN RANGE 141923Z FEB 18.

Date: 201028Z FEB 18
Cancel: 26093000 Feb 18

RocketLover0119 · « **Reply #63 on:** 02/21/2018 08:48 pm »

um.........so....... Ocisly is leaving port right now. Maybe Govsats crazy return boosted confidence to go for this? It also is a Block IV core so.......

Nehkara · « **Reply #64 on:** 02/21/2018 09:23 pm »

WOW!

This is exciting!

Can't wait to watch this webcast.

GeneBelcher · « **Reply #65 on:** 02/21/2018 09:35 pm »

Since this seems like an experimental landing attempt, I think this is a good candidate for a game of bingo!

lrk · « **Reply #66 on:** 02/21/2018 10:32 pm »

Quote from: RocketLover0119 on 02/21/2018 08:48 pm

um.........so....... Ocisly is leaving port right now. Maybe Govsats crazy return boosted confidence to go for this? It also is a Block IV core so.......

Yeah, I was kinda surprised they would be using titanium grid fins on a core they planned to splash. Makes sense if this is a hot recovery attempt.

sevenperforce · « **Reply #67 on:** 02/21/2018 10:35 pm »

Quote from: lrk on 02/21/2018 10:32 pm

Quote from: RocketLover0119 on 02/21/2018 08:48 pm
um.........so....... Ocisly is leaving port right now. Maybe Govsats crazy return boosted confidence to go for this? It also is a Block IV core so.......

Yeah, I was kinda surprised they would be using titanium grid fins on a core they planned to splash. Makes sense if this is a hot recovery attempt.

Do we have confirmation of Ti fins? I didn't think we had eyes on the booster yet.

Lar · « **Reply #68 on:** 02/21/2018 10:50 pm »

We have reports but not pics

Michael Baylor · « **Reply #69 on:** 02/21/2018 11:03 pm »

Quote from: GeneBelcher on 02/21/2018 09:35 pm

Since this seems like an experimental landing attempt, I think this is a good candidate for a game of bingo!

Hopefully it doesn't turn into NSF Battleship.

LouScheffer · « **Reply #70 on:** 02/21/2018 11:59 pm »

If they can land this thing with a 6.1t payload I'll be really impressed.

The best previous recovery was 5.3t. Upping the payload to 6.1t will cost the second stage about 250 m/s. Since the 5.3t launches staged at 2300 m/s, Hispasat would need to stage as 2550 m/s or so. This is less than the Falcon Heavy core, but more than any other recovery.

Where could this extra 250 m/s come from? An aggressive 3 engine burn could save 9-engine seconds, enough for 1 second more thrust. So about 50 m/s of that. Also they could go into a just-barely-GTO orbit, and save 50 m/s more.

Where could the other 150 m/s come from? It's a new core, and could feature higher thrust and reduced gravity losses. Alternatively, could they cut 9 seconds off the re-entry burn? SES-11 has a 20 second re-entry burn, as did FH. Could they cut it down to 11 seconds and let drag do the rest? Seems like a stretch. Or they could go to a sub-sync orbit...

So my guess is this new core has the higher thrust engines, and the remaining extra speed comes from reduced gravity loss, and maybe slightly higher ISP from the higher chamber pressure. We'll know if has a shorter burn time, since higher thrust means faster consumption.

Lar · « **Reply #71 on:** 02/22/2018 12:39 am »

We have seen block 4 before so unless this is a 4.5 or something I don't see the higher thrust part as all that likely. I also can't see them fudging the orbit much.

My theory for the bulk of the shortfall is increased drag from flying a higher angle of attack, which is enabled by the bigger, sturdier grid fins, and thus a far shorter reentry burn.

IanThePineapple · « **Reply #72 on:** 02/22/2018 12:42 am »

Quote from: Michael Baylor on 02/21/2018 11:03 pm

Quote from: GeneBelcher on 02/21/2018 09:35 pm
Since this seems like an experimental landing attempt, I think this is a good candidate for a game of bingo!
Hopefully it doesn't turn into NSF Battleship.

You sunk my drone ship!

LouScheffer · « **Reply #73 on:** 02/22/2018 01:43 am »

Quote from: Lar on 02/22/2018 12:39 am

We have seen block 4 before so unless this is a 4.5 or something I don't see the higher thrust part as all that likely.

I see no reason they need to switch the engines and the rest of the booster at the same time. If I were SpaceX, I'd start making only the uprated engines as soon as they were qualified. If that's before the rest of the block 5 is ready, no big deal. Just stick them on the model 4 core and enjoy the benefits. Exactly like they did with the titanium fins.

What's the alternative in this case? Deliberately build less-useful engines?

So my vote is a model 4.5 core.

Lar · « **Reply #74 on:** 02/22/2018 02:54 am »

That presumes that whatever tweaks happened in the business end (plumbing, shielding, actuators, whatever) don't preclude that.

In automotive often a small change to one side of an interface requires a corresponding change to the other side so both have to change in step (which makes MRP harder, you have to make the right amount of the old parts)

I hope you're right and i have no reason to believe you're not. But a higher angle of attack would be cool too.

OneSpeed · « **Reply #75 on:** 02/22/2018 07:32 am »

Quote from: LouScheffer on 02/21/2018 11:59 pm

If they can land this thing with a 6.1t payload I'll be really impressed.

So will I.

Quote from: LouScheffer on 02/21/2018 11:59 pm

The best previous recovery was 5.3t. Upping the payload to 6.1t will cost the second stage about 250 m/s. Since the 5.3t launches staged at 2300 m/s, Hispasat would need to stage as 2550 m/s or so. This is less than the Falcon Heavy core, but more than any other recovery.

Where could this extra 250 m/s come from? An aggressive 3 engine burn could save 9-engine seconds, enough for 1 second more thrust. So about 50 m/s of that. Also they could go into a just-barely-GTO orbit, and save 50 m/s more.

Where could the other 150 m/s come from? It's a new core, and could feature higher thrust and reduced gravity losses. Alternatively, could they cut 9 seconds off the re-entry burn? SES-11 has a 20 second re-entry burn, as did FH. Could they cut it down to 11 seconds and let drag do the rest? Seems like a stretch. Or they could go to a sub-sync orbit...

Perhaps some ∆V could also be found from the second stage? If the webcast velocities are correct, we've occasionally seen S2 thrust at about 107% of the published figures. They've usually only maintained these levels for the first minute or so of the burn before throttling back to 94% or so. But if they did run harder for longer, they could reduce S2 gravity losses by quite a bit.

Jet Black · « **Reply #76 on:** 02/22/2018 09:06 am »

Quote from: Lar on 02/22/2018 02:54 am

That presumes that whatever tweaks happened in the business end (plumbing, shielding, actuators, whatever) don't preclude that.

On that, do we know whether the TEA-TEB tanks will be easy to modify given that they ran out in the FH, or will require similar adjustment of multiple parts?

Ugger55 · « **Reply #77 on:** 02/22/2018 10:30 am »

Does anyone remember where the payload weights to re-entry success curve chart is? I've been looking for it for an hour (google-fu is lacking)

Even for an "experimental" landing, there must still be high confidence for the Ti fins. I think it'll be further refinement of existing burns rather than hardware changes and their being confident of the exact limits they can push a booster too

Thanks

Quote from: LouScheffer on 02/21/2018 11:59 pm

If they can land this thing with a 6.1t payload I'll be really impressed.

The best previous recovery was 5.3t. Upping the payload to 6.1t will cost the second stage about 250 m/s. Since the 5.3t launches staged at 2300 m/s, Hispasat would need to stage as 2550 m/s or so. This is less than the Falcon Heavy core, but more than any other recovery.

tvg98 · « **Reply #78 on:** 02/22/2018 12:17 pm »

https://twitter.com/SpaceflightNow/status/966662404770852866

It looks like B1044 does have Ti fins after all. Not really a surprise given that they'll attempt to recover it, but still worth noting.

sevenperforce · « **Reply #79 on:** 02/22/2018 12:20 pm »

Quote from: OneSpeed on 02/22/2018 07:32 am

Perhaps some ∆V could also be found from the second stage? If the webcast velocities are correct, we've occasionally seen S2 thrust at about 107% of the published figures. They've usually only maintained these levels for the first minute or so of the burn before throttling back to 94% or so. But if they did run harder for longer, they could reduce S2 gravity losses by quite a bit.

I don't think gravity losses on S2 are enough to make much of a difference.