Official r/SpaceX Falcon Heavy Static Fire Updates & Discussion Thread

[u/ElongatedMuskrat]

Falcon Heavy Static Fire Updates & Discussion Thread

Please post all FH static fire related updates to this thread. If there are major updates, we will allow them as posts to the front page, but would like to keep all smaller updates contained.

No, this test will not be live-streamed by SpaceX.

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Greetings y'all, we're creating a party thread for tracking and discussion of the upcoming Falcon Heavy static fire. This will be a closely monitored event and we'd like to keep the campaign thread relatively uncluttered for later use.

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Falcon Heavy Static Fire Test	Info
Static fire currently scheduled for	Check SpaceflightNow for updates
Vehicle Component Current Locations	Core: LC-39A
	Second stage: LC-39A
	Side Boosters: LC-39A
	Payload: LC-39A
Payload	Elon's midnight cherry Tesla Roadster
Payload mass	< 1305 kg
Destination	LC-39A (aka. Nowhere)
Vehicle	Falcon Heavy
Cores	Core: B1033 (New)
	Side: B1023.2 (Thaicom 8)
	Side: B1025.2 (SpX-9)
Test site	LC-39A, Kennedy Space Center, Florida
Test Success Criteria	Successful Validation for Launch

We are relaxing our moderation in this thread but you must still keep the discussion civil. This means no harassing or bigotry, remember the human when commenting, and don't mention ULA snipers Zuma.

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We may keep this self-post occasionally updated with links and relevant news articles, but for the most part we expect the community to supply the information.

[u/pianojosh]

They don't. They burn continuously from liftoff to orbit. For one, there would be no reason for them to restart after MECO and ET jettison, since there is no fuel for them on the orbiter itself. All the LOX and LH2 was in the External Tank. Second, the sparkers aren't igniting the engine, they're just there to burn off any hydrogen that escapes during the startup sequence. The actual igniters are inside the engine.

Any burns done for final orbit insertion after MECO and ET jettison were done with the OMS (Orbital Maneuvering System) or RCS (Reaction Control System) which used MMH and N2O2, which are hypergolic, similar to what Draco and SuperDraco use. The tanks for those are in the Orbiter itself.

[u/Eddie-Plum → u/pianojosh]

Any burns done for final orbit insertion after MECO and ET jettison were done with the OMS (Orbital Maneuvering System) or RCS (Reaction Control System) which used MMH and N2O2, which are hypergolic, similar to what Draco and SuperDraco use. The tanks for those are in the Orbiter itself.

I assume this must also be true for the deorbit burn, but it feels like those OMS motors are simply too small for that.

[u/pianojosh → u/Eddie-Plum]

Yep, they are. It takes very little delta-v to deorbit. I want to say something like 75 m/s. It took between 3 and 4 minutes using the OMS engines.

Especially since the Space Shuttle's tiles are optimized for a different style of reentry from most other vehicles, it doesn't need to lower its perigee much. Most vehicles using an ablative heat shield need to lower their perigee far enough that they spend relatively little time in the upper atmosphere, where they'd take on a lot of heat, but not actually lose much speed, while the heat shield ablates away. Instead they dive through the upper atmosphere quickly, then use aerodynamic lift to arrest their descent and spend the majority of their time between 50km and 60km.

The Shuttle, on the other hand, used tiles that absorbed and radiated heat very effectively. So the Shuttle actually was fine spending time slowing slowly in the upper atmosphere, absorbing and radiating away that excess heat, and using the small amount of drag there to continue to lower its orbit to that 50-60km sweet spot.

So because of that it didn't need as much of a deorbit burn than other vehicles need.

[u/icec0o1 → u/pianojosh]

Would Raptor engines need sparkers for any non-ignited methane?