Author Topic: SpaceX Falcon 9 : Hispasat 30W-6 (1F) : March 6, 2018 - DISCUSSION (Read 164925 times)

LouScheffer · « **Reply #240 on:** 03/05/2018 06:44 pm »

Compared to Inmarsat 5, a satellite of similar mass with a non-recovery launch, the second stage is burning 10 seconds less (2:35 as opposed to 2:45).

Either they are still reserving fuel for a recovery attempt, or these are new higher thrust engines that can chew through the same amount of fuel in less time.

The time is 94% of the previous mission, so about a 6% thrust uprating if that's the cause. On the other hand, 10 seconds is just a little more than they typically reserve for recovery (20 seconds x 3 engines for re-entry, 30 seconds one engine for landing). An aggressive 3 engine landing burn might save 9 engine-seconds, and reduce the total deficit to 9 seconds of boost. So my guess is still uprated engines, and 2:35 burns to depletion.

gongora · « **Reply #241 on:** 03/05/2018 06:50 pm »

I don't know if they'd bother changing the flight profile when the mission is changed from recovery to expendable. The customer paid for a certain level of performance that was agreed to ahead of time. The don't really need to provide higher performance. (This shift in getting customers to accept not necessarily using the full performance of the rocket is just as big a part of reuse as getting the customers to accept that the reused boosters won't blow up.)

Barrie · « **Reply #242 on:** 03/05/2018 06:55 pm »

The Ti fins had been interpreted as a sign of confidence that this recovery had a good chance of success; maybe it always was a long-shot, push-the-envelope test after all.

LouScheffer · « **Reply #243 on:** 03/05/2018 07:06 pm »

Quote from: jpo234 on 03/05/2018 06:55 pm

https://twitter.com/elonmusk/status/970747812311740416?s=20

Quote
Falcon 9 flight 50 launches tonight, carrying Hispasat for Spain. At 6 metric tons and almost the size of a city bus, it will be the largest geostationary satellite we’ve ever flown.

Wasn't Intelsat 6.7 metric tons, and went to GTO? Maybe he means largest in physical size, though that would be odd.

matthewkantar · « **Reply #244 on:** 03/05/2018 07:21 pm »

I think SpaceX now knows how to land a booster in the water so that it stays intact, or at least has a good chance of doing so. Getting the grid fins off of a stage in a rough sea safely? Not trivial for sure.

Matthew

sevenperforce · « **Reply #245 on:** 03/05/2018 07:26 pm »

Quote from: LouScheffer on 03/05/2018 07:06 pm

Wasn't Intelsat 6.7 metric tons, and went to GTO? Maybe he means largest in physical size, though that would be odd.

IIRC Intelsat was 6 tonnes even.

Elthiryel · « **Reply #246 on:** 03/05/2018 07:30 pm »

Gunter's page says Intelsat 35e was 6761 kg, so definitely heavier than Hispasat. Elon either meant a physical size or simply got it wrong.

http://space.skyrocket.de/doc_sdat/intelsat-35e.htm

rsdavis9 · « **Reply #247 on:** 03/05/2018 07:38 pm »

Or he meant 6 tonnes GTO which could have been reusable.

EDIT: heaviest sat to GTO with recovery is SES-10 at 5300kg.

https://en.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_Heavy_launches#2017

Nomadd · « **Reply #248 on:** 03/05/2018 08:06 pm »

If the weather is too much for a tug, it's going to be way too much for a barge landing. You'd probably still lose the booster and might put the barge out of commision.
Having exactly as many barges as they require has always seemed a little risky to me. If they get where they want with the Block 5s, losing one for lack of an ASDS is going is going to hurt.

sevenperforce · « **Reply #249 on:** 03/05/2018 08:16 pm »

What is worth more to them, an ASDS or a Block V booster?

The ASDS is obviously easier to reuse, but....

Roy_H · « **Reply #250 on:** 03/05/2018 08:55 pm »

Quote from: sevenperforce on 03/05/2018 08:16 pm

What is worth more to them, an ASDS or a Block V booster?

The ASDS is obviously easier to reuse, but....

You mean block IV, don't you? I don't think that is an either/or option. Most likely in that rough sea condition they would loose both.

What I don't understand is why not remove grid fins and legs? Significant cost savings even though performance increase is not required and it would have the benefit of increased performance margin.

Truncate · « **Reply #251 on:** 03/05/2018 09:02 pm »

Quote from: Barrie on 03/05/2018 06:55 pm

The Ti fins had been interpreted as a sign of confidence that this recovery had a good chance of success; maybe it always was a long-shot, push-the-envelope test after all.

Out of curiosity, does anyone have an idea of how much those Ti grin fins cost? I seem to recall Elon mentioning that they were really really expensive.

Lar · « **Reply #252 on:** 03/05/2018 09:14 pm »

Quote from: Rebel44 on 03/05/2018 04:08 pm

Quote from: jpo234 on 03/05/2018 03:49 pm
Quote from: TorenAltair on 03/05/2018 03:45 pm
They could just try to water-land it and perhaps salvage the fins then. How fast could a tug be there without pulling a barge?

I don't think they can intentionally do this. The F9 is ITAR controlled. Leaving it intentionally salvageable in international waters even for a short time is almost certainly an ITAR violation.

Wrong

Water landings (before SpaceX started attempts to land on ASDS) tried to do exactly that.

Salvage only applies to something that has been abandoned, so if the stage was landed with intention of being retrieved, it's not ever abandoned. So salvage rights are not available, if I understand it correctly. (IANAL, especially not a marine lawyer)

TorenAltair · « **Reply #253 on:** 03/05/2018 09:39 pm »

Very, very rough guesstimate: fins are about 1.59 x 1.23 x 0.2 m gives about 0.39 cubic meters
Ti is about $20/kg
Density 4500 kg/m^3
“Holes“ inside the fins perhaps 90% before shaping into flight form.. so 4 fins x 0.04 m^3 x 4500 kg/m^3 is about 720 kg if I entered numbers correctly on the tablet. So material cost not that much... $14400. Add a lot of energy and labour time.

Small tools with a few dozen grams cost about $500-1000. Let's take the 400 kg finished fins after shaping and $500/100g makes $2 millions.

jpo234 · « **Reply #254 on:** 03/05/2018 09:41 pm »

Quote from: Roy_H on 03/05/2018 08:55 pm

Quote from: sevenperforce on 03/05/2018 08:16 pm
What is worth more to them, an ASDS or a Block V booster?

The ASDS is obviously easier to reuse, but....

You mean block IV, don't you? I don't think that is an either/or option. Most likely in that rough sea condition they would loose both.

What I don't understand is why not remove grid fins and legs? Significant cost savings even though performance increase is not required and it would have the benefit of increased performance margin.

The legs are probably worthless if Block 5 uses a new design. But I am really perplexed about the fins.

kdhilliard · « **Reply #255 on:** 03/05/2018 09:47 pm »

Quote from: FutureSpaceTourist on 03/05/2018 03:41 pm

Press kit attached.

Edit: patch added

Anyone else think it strange the patch shows the Falcon 9 with all engines firing, but cut off at the top of the interstage?

cppetrie · « **Reply #256 on:** 03/05/2018 10:03 pm »

Quote from: kdhilliard on 03/05/2018 09:47 pm

Quote from: FutureSpaceTourist on 03/05/2018 03:41 pm
Press kit attached.

Edit: patch added

Anyone else think it strange the patch shows the Falcon 9 with all engines firing, but cut off at the top of the interstage?

Landing or entry burn?

RocketLover0119 · « **Reply #257 on:** 03/05/2018 10:10 pm »

When are the remote camerists going for remote camera set ups?

Mader Levap · « **Reply #258 on:** 03/05/2018 10:27 pm »

Quote from: kdhilliard on 03/05/2018 09:47 pm

Anyone else think it strange the patch shows the Falcon 9 with all engines firing, but cut off at the top of the interstage?

There is something called "artistic license".

gongora · « **Reply #259 on:** 03/05/2018 10:34 pm »

Looks like this flight is using the older fairing design.