Author Topic: SpaceX Falcon 9 : Hispasat 30W-6 (1F) : March 6, 2018 - DISCUSSION  (Read 161148 times)

Offline envy887

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... At MECO, the apogee is already at orbital altitude.  So the second stage can just thrust horizontally while it coasts up to LEO, and does not need to fight gravity.

At MECO, S2 is flying at best at one third of orbital velocity. To maintain its apogee at orbital altitude, while accelerating at only around 1g, it needs to fly with a substantial AoA, and hence cosine losses. You can see this for yourself in the webcasts. It can only fly horizontally and maintain altitude once it has reached orbital velocity.
Higher thrust reduces the AoA required to maintain altitude, thus reducing cosine losses.

Or they could loft the booster trajectory, giving the upper stage enough vertical velocity to thrust only horizontally and reach orbital speed before falling back into the atmosphere. Then higher upper stage thrust reduces the required lofting.

Either way, higher upper stage thrust reduces gravity losses.

Offline rpapo

It doesn't - density is about 4.5 g/cm3. The three metals with densities less than water are lithium, potassium, and sodium, but building floating structures out of those would be, shall we say, problematic.
Yeah.  They burn.  Violently.
Following the space program since before Apollo 8.

Offline cscott

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It's also possible that the Ti fins were precious only (or primarily) because they were on the critical path for FH demo.  Now that's done, there is perhaps a bit more lead time to acquire a replacement if necessary.

In fact, my belief is that the milled Ti fins were in fact just prototypes. Now that FH has been successful, they may be moving on to the "production" Ti fins, which would be forged ("largest Ti forging" as Elon once promised).  So this flight could be a bit more careless about potentially expending the development prototype fins, which are EOL anyway.

Offline LouScheffer

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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.
Here is why I think this is a model 4.5 booster.   It's way out of family for any other GTO mission.  (Data from stcks F9 to GTO page.

[... chart deleted ...]
More evidence for a block 4.5 .  If you draw a line through the latest expendable launches, and extrapolate to to GEO-1800, you get about 7300 kg to GTO with an expendable block 4.   Add in the improvement we see in this mission, you get 8.1t to GTO.   SpaceX claims 8.3t to GTO with block 5, so we are seeing almost all the improvement there is in block 5.

Or conversely, a full block 5, according to SpaceX, could loft 8.3t to GTO, expendable.  Derate that for recovery, at the observed rates, and a full block 5 could loft 6.3t expendable recoverable.   This one is 6.1t, so if it's a stock GTO orbit, we're seeing very close to full block 5 performance.

EDIT:  Fix error shown by strikethrough.
« Last Edit: 02/26/2018 03:24 pm by LouScheffer »

Offline OneSpeed

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More evidence for a block 4.5 .  If you draw a line through the latest expendable launches, and extrapolate to to GEO-1800, you get about 7300 kg to GTO with an expendable block 4.   Add in the improvement we see in this mission, you get 8.1t to GTO.   SpaceX claims 8.3t to GTO with block 5, so we are seeing almost all the improvement there is in block 5.

Or conversely, a full block 5, according to SpaceX, could loft 8.3t to GTO, expendable.  Derate that for recovery, at the observed rates, and a full block 5 could loft 6.3t expendable.   This one is 6.1t, so if it's a stock GTO orbit, we're seeing very close to full block 5 performance.

Perhaps Block 5 engines at less than 100% thrust?. Either way, it will be fascinating to see the actual launch numbers.

Offline Johnnyhinbos

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With the stage looking like it has titanium fins, per https://forum.nasaspaceflight.com/index.php?topic=44695.msg1791981#msg1791981,  may be worth doing salvage if they lose the stage.
anyone know the cost of those fins?
jb

It's not really their cost but more the time and labor needed to make them (So yes, cost is also a problem with those when you add in all the prices of the labor and machinery).

Titanium doesn't float on water AFAIK, so if they lose the stage there's a really good chance they lose the fins too. If the fins land fairly intact on the deck of OCISLY they may be salvageable, but most of the past landing failures have involved a large portion of the vehicle falling off the ship.

Can’t contribute much to this conversation other to say my rebreather is made out of titanium and it _definitely_ doesn’t float . (That would be contrary to the desired activity of sinking...)

John Hanzl. Author, action / adventure www.johnhanzl.com

Offline smh

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Or conversely, a full block 5, according to SpaceX, could loft 8.3t to GTO, expendable.  Derate that for recovery, at the observed rates, and a full block 5 could loft 6.3t expendable.   This one is 6.1t, so if it's a stock GTO orbit, we're seeing very close to full block 5 performance.
You mean 6.3t recoverable?

Offline lrk

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Could it simply just be a block 5 upper stage flying on a standard block 4 booster?  Similarly to how a couple of block 4 upper stages flew on block 3 boosters before the first flight of a block 4 booster? 

Offline Bubbinski

The launch has been delayed past this weekend, they’re doing some additional testing on the fairing’s pressurization system. I thought the fairing issues were over with, the ZUMA launch had been delayed due to fairing issues. Is this related to fairing 2.0 or some other thing like a factory problem?
« Last Edit: 02/24/2018 04:53 am by Bubbinski »
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

Offline IanThePineapple

The launch has been delayed past this weekend, they’re doing some additional testing on the fairing’s pressurization system. I thought the fairing issues were over with, the ZUMA launch had been delayed due to this. Is this related to fairing 2.0 or some other thing like a factory problem?

[GUESS] My guess is that it might be flying with fairing 2.0 or just checking/doing maintenance on a 1.0 from lessons learned from the 2.0 flight on Paz. [/GUESS]
« Last Edit: 02/24/2018 04:51 am by IanThePineapple »

Offline Paul_G

Quote
Standing down from this weekend's launch attempt to conduct additional testing on the fairing’s pressurization system. Once complete, and pending range availability, we will confirm a new targeted launch date.

Do we know how the pressurisation system works? Is it active or passive? If further tests are needed I guess this makes it more complex than the vents we see at the base of the fairing with the tear away covers on. If further tests are needed, it sounds like valves and things are involved.

Paul
« Last Edit: 02/24/2018 10:44 am by Paul_G »

Offline speedevil

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Do we know how the pressurisation system works? Is it active or passive? If further tests are needed I guess this makes it more complex than the vents we see at the base of the fairing with the tear away covers on. If further tests are needed, it sounds like valves and things are involved.

I wonder if it might be a reference to the various pressurised gas systems now in the fairing.

Offline niwax

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SpaceX Stats now lists the launch for Wednesday evening, no confirmation from SX or Musk twitter
Which booster has the most soot? SpaceX booster launch history! (discussion)

Offline Johnnyhinbos

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Quote
Standing down from this weekend's launch attempt to conduct additional testing on the fairing’s pressurization system. Once complete, and pending range availability, we will confirm a new targeted launch date.

Do we know how the pressurisation system works? Is it active or passive? If further tests are needed I guess this makes it more complex than the vents we see at the base of the fairing with the tear away covers on. If further tests are needed, it sounds like valves and things are involved.

Paul
The fairing is ambient, so the reference to pressurizing must relate to the gas systems inside - such as for separation and recovery...
John Hanzl. Author, action / adventure www.johnhanzl.com

Offline sewebster

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The don't mean fairing HVAC system used on the pad?

Offline AC in NC

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SpaceX Stats now lists the launch for Wednesday evening, no confirmation from SX or Musk twitter

That's counting down to Wednesday AM not evening.


eta:  Now updated to the very early Thursday morning 0034L T-0
« Last Edit: 02/26/2018 03:22 pm by AC in NC »

Offline LouScheffer

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Keeping score at home:  Assuming that HispaSat is 6100 kg, and they recover (or close to recover) the booster, then something must have changed.   Previous max mass (5300 kg) recoverable missions staged at  about 8450 kmhr.  Here are 4 theories that have been proposed here and how we can tell them apart, in real time while watching the webcast.

(a) Staging less than 9000 km/hr, and transfer orbit short of GTO.: Regular block 4.  Customer accepted less than full GTO, possibly in return for recoverable discount.
(b) Staging less than 9000 km/hr, and transfer orbit GTO or greater:   Second stage must have been upgraded.
(c) Staging >= 9000 km/r, entry burn is about 20 seconds:  Must be a block 4.5 booster.  4.0 could not get to this speed with 20 seconds of entry burn fuel left.
(d) Staging >= 9000 km/hr, entry burn is about 10 seconds:  Block 4, titanium fins allow more slowing by drag and less by engine.

In any case we expect a maximally downrange ASDS and an aggressive 3-engine landing burn, since this mission is clearly marginal in terms of recovery.

Or, of course, it's also possible that SpaceX surprises us and it's none of these.

EDIT:  to tell if GTO has a GEO or greater apogee, look for a second stage cutoff speed of 35,280 km/hr (9800 m/s) or more, in the SpaceX telemetry coordinate system.
« Last Edit: 02/26/2018 07:22 pm by LouScheffer »

Online mn

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March 1 Range Requested (pending Range Approval).

Isn't GOES-S launching on March 1st?

Can the range really support two launches on the same day?

(I know they want to get there, but are they there yet?)

Offline russianhalo117

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March 1 Range Requested (pending Range Approval).

Isn't GOES-S launching on March 1st?

Can the range really support two launches on the same day?

(I know they want to get there, but are they there yet?)
Yes, it is confirmed when talking about 2 F9's on the same day from Florida due to AFTS being used on both launchers. As for 2 adjacent pads with different launchers that is the unconfirmed part, but the CCAFS range plan is to make it where type of launcher doesn't matter. AFTS would be the factor at play.
« Last Edit: 02/26/2018 05:40 pm by russianhalo117 »

Online mn

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March 1 Range Requested (pending Range Approval).

Isn't GOES-S launching on March 1st?

Can the range really support two launches on the same day?

(I know they want to get there, but are they there yet?)
Yes, it is confirmed when talking about 2 F9's on the same day from Florida due to AFTS being used on both launchers. As for 2 adjacent pads with different launchers that is the unconfirmed part, but the CCAFS range plan is to make it where type of launcher doesn't matter. AFTS would be the factor at play.

I don't recall seeing anything about Atlas V having AFTS

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