Long term thoughts on hot staging and hot staging ring integration into booster.Right now Starship has 3 vacuum Raptors, but that is eventually going to be 6. With three vacuum Raptors things don't balance out nicely for exhaust during staging separation. All must be fired, and exhaust from one or two will blow hard on the grid fin hardware and of its protection. With 6, 2 could be initially fired for hot staging and have lots of space for exhaust to escape. The grid fin hardware can stay above the dome. Putting it inside the tank is a PITA. For this I'm aligning the two that are fired 90 degrees to the vertical plane through the catch pins. This centers them in the area between the grid fin hardware. They now have plenty of space for exhaust to escape.
Exhaust vents will be as much as possible all the way around. For aesthetics reasons I don't expect to see a triangulated tube system, or we'd already have it.
That image seems to show the grid fin motors moving into the upper tank - at the very least, they're mounted significantly lower than on the current boosters.And it shows the upper dome sticking ABOVE the walls of the booster.
Long term thoughts on hot staging and hot staging ring integration into booster.Right now Starship has 3 vacuum Raptors, but that is eventually going to be 6. With three vacuum Raptors things don't balance out nicely for exhaust during staging separation. All must be fired, and exhaust from one or two will blow hard on the grid fin hardware and of its protection. With 6, 2 could be initially fired for hot staging and have lots of space for exhaust to escape. The grid fin hardware can stay above the dome. Putting it inside the tank is a PITA. For this I'm aligning the two that are fired 90 degrees to the vertical plane through the catch pins. This centers them in the area between the grid fin hardware. They now have plenty of space for exhaust to escape.Exhaust vents will be as much as possible all the way around. For aesthetics reasons I don't expect to see a triangulated tube system, or we'd already have it.I suspect COPVs, guidance computers and other hardware tucked in at the top of the tank will be moved to the tops of the chines. Less vibrations during hot staging. Some could be tucked under the grid fin hardware, but that space is at a premium for grid fin actuator hardware and supports. It may also require grid fin hardware removal for its maintenance.Even for 3 vacuum raptor Starships, I expect the hot staging top for the booster will migrate to what I described above. The grid fin hardware protection shields must be able to handle 3+ engine hot staging fires if there is failure to light either of the two initially fired engines.
Quote from: Eka on 11/14/2024 08:14 amLong term thoughts on hot staging and hot staging ring integration into booster.Right now Starship has 3 vacuum Raptors, but that is eventually going to be 6. With three vacuum Raptors things don't balance out nicely for exhaust during staging separation. All must be fired, and exhaust from one or two will blow hard on the grid fin hardware and of its protection. With 6, 2 could be initially fired for hot staging and have lots of space for exhaust to escape. The grid fin hardware can stay above the dome. Putting it inside the tank is a PITA. For this I'm aligning the two that are fired 90 degrees to the vertical plane through the catch pins. This centers them in the area between the grid fin hardware. They now have plenty of space for exhaust to escape.Exhaust vents will be as much as possible all the way around. For aesthetics reasons I don't expect to see a triangulated tube system, or we'd already have it.I suspect COPVs, guidance computers and other hardware tucked in at the top of the tank will be moved to the tops of the chines. Less vibrations during hot staging. Some could be tucked under the grid fin hardware, but that space is at a premium for grid fin actuator hardware and supports. It may also require grid fin hardware removal for its maintenance.Even for 3 vacuum raptor Starships, I expect the hot staging top for the booster will migrate to what I described above. The grid fin hardware protection shields must be able to handle 3+ engine hot staging fires if there is failure to light either of the two initially fired engines.Are two engines sufficient to pull a fully tanked Starship away from a mostly depleted Superheavy with engines running?
Quote from: KilroySmith on 11/14/2024 03:39 pmThat image seems to show the grid fin motors moving into the upper tank - at the very least, they're mounted significantly lower than on the current boosters.And it shows the upper dome sticking ABOVE the walls of the booster. Pointing out mistakes (if any) is just a distraction from the fact that the graphics designer was definitely instructed to replace the existing hot staging ring with a tube truss design. Unless your theory is that their pen slipped? Or they were told to just make up the entire thing willy-nilly with zero instructions given?For aesthetic and functional reasons I expect to see a triangulated tube system (plus, otherwise the illustration wouldn't have it).Physics says it's better. Manufacturability says it's better. Cost says it's better. Mass says it's better. And SpaceX has tipped their hand that this is their ultimate plan. On the counter-argument side, all we have is... what again? One guy doesn't like the look?
To analyze Starship�s hot staging maneuver, researchers in the Fluid Dynamics Branch at NASA�s Marshall Space Flight Center performed computational fluid dynamics (CFD) simulations using the Loci/CHEM flow solver. These simulations included steady-state simulations as well as sophisticated time-accurate moving body simulations on a variety of iterations of the Starship geometry. Due to the scale of the problem, meshes of approximately 500 million cells were required. The team simulated various engine startup sequences and analyzed the resulting aerodynamic loads. Flight data from Starship�s second Integrated Flight Test (IFT2) compared favorably to the CFD results. These simulations supported SpaceX in designing a successful hot-staging separation.
