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Do we have any explanation for why they're bringing it down in the Indian Ocean rather than near Barking Sands missile test range like they'd planned for IFT-2? The test objectives for IFT-3 seem to be less ambitious than before? (i.e. Re-entry over the Indian Ocean suggests a suborbital, Space Shuttle main tank style,  trajectory rather than actually reaching the true orbital speed necessary to reach Hawaii?)

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22 minutes ago, PakledHostage said:

Do we have any explanation for why they're bringing it down in the Indian Ocean rather than near Barking Sands missile test range like they'd planned for IFT-2? The test objectives for IFT-3 seem to be less ambitious than before? (i.e. Re-entry over the Indian Ocean suggests a suborbital, Space Shuttle main tank style,  trajectory rather than actually reaching the true orbital speed necessary to reach Hawaii?)

This is mostly speculative, but it's possible that they will be putting it into the original trajectory from IFT-2, then executing a radial-in burn to ditch in the Indian Ocean instead. Alternatively they may do an acceleration burn just before re-entry.

The second stage failure in IFT-2 was the result of the LOX dump that took place at the end of the burn. Because IFT-2 wasn't a true orbit, they didn't need quite as much propellant in the second stage as  they would have otherwise needed. HOWEVER, they still wanted it to be as close as possible to an ordinary flight for T/W ratio reasons, so while they carried only as much CH4 as they needed, they carried significantly more LOX. Slosh of this LOX would have interfered with center-of-mass balance during re-entry, though, so they dumped the LOX out the back end just as they were approaching orbital velocity. This somehow caused an explosion (possibly due to some sort of leak of fuel-rich turbopump exhaust or fuel-rich pressurant). Presumably they didn't want to dump the LOX after reaching orbital velocity because they didn't want to risk the dump causing a propulsive effect that shifted the impact zone.

For this test, it seems like the plan is to carry a full propellant load (both LOX and CH4) but never dump propellant. Instead they will cut off early, perform the tests (prop transfer and payload door operation) during ballistic coast, then relight the engines to both (a) burn off the remaining propellant and (b) alter their trajectory. This could be a radial burn at apogee that alters their impact point from Hawaii to the Indian Ocean, or it could be a prograde burn that increases their velocity just before re-entry in order to better simulate re-entry speeds. 

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2 hours ago, sevenperforce said:

Presumably they didn't want to dump the LOX after reaching orbital velocity because they didn't want to risk the dump causing a propulsive effect

I’m guessing they need thrust for ullage to dump the LOX, especially at any reasonable flow rate. 

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17 hours ago, sevenperforce said:

This is mostly speculative, but it's possible that they will be putting it into the original trajectory from IFT-2, then executing a radial-in burn to ditch in the Indian Ocean instead. Alternatively they may do an acceleration burn just before re-entry.

I’m thinking not, since there’s no precautionary TFRs in the Pacific, at least not yet. My impression is they’re staying well suborbital, then burning normal/antinormal, prograde dive, etc, in such a way not to move the entry corridor much, specifically because they don’t want it coming down over Australia or such if the engine burn fails for any reason. First light of a Raptor in space & all.

Now I’m wondering if that engine burn might be what actually moves the fuel transfer, too. 

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Wait, abort! I can't believe I fell for that. :blush: Fake FAA account.

I can take some solace that NSF fell for it too (their tweet was quickly deleted).

 

Edited by Spaceception
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24 minutes ago, Ultimate Steve said:

Anyone have a picture of the fake tweet? All I've seen are people referencing it and not what it actually is.

It looked official, and a lot of other people ran with it before realizing what it was, but it was spread fairly far across space twitter in a short amount of time, so there was some delay in people getting excited, and then realizing it was fake (I, and a lot of people got carried away).

I think this is the best I've got (click to expand), they retweeted their own post, but below that was a link to, I think, the license announcement for IFT-2. But they were just suspended.

 

Edited by Spaceception
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3 hours ago, Spaceception said:

Wait, abort! I can't believe I fell for that. :blush: Fake FAA account.

I can take some solace that NSF fell for it too (their tweet was quickly deleted).

 

What are you talking about?

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8 minutes ago, JoeSchmuckatelli said:

Speaking of getting trolled... I don't know if this is new or not - but the video is 16 hours old.

 

I found it on Space.com and yet its on DailyMotion, so...

Edit - and apparently not loading?

Nothing coming through here either.  What was the topic?

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On 3/8/2024 at 9:03 AM, CatastrophicFailure said:

I’m thinking not, since there’s no precautionary TFRs in the Pacific, at least not yet. My impression is they’re staying well suborbital, then burning normal/antinormal, prograde dive, etc, in such a way not to move the entry corridor much, specifically because they don’t want it coming down over Australia or such if the engine burn fails for any reason. First light of a Raptor in space & all.

Now I’m wondering if that engine burn might be what actually moves the fuel transfer, too. 

It sounds a bit weird, they have to burn second stage for quite some time anyway and dV difference between west of Australia to west of Hawaii is not very large, they also have to overfly Africa anyway. 
Now Australia indicates an more southern trajectory than Hawaii, It might be that they don't want to dump oxygen and simply terminate mission on reentry. 
My guess mission is to test second stage ignition, separation, and first stage return burn. It quite some time to they can recover second stage but they want to start reusing first stages soon. 

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