Updated and revised SpaceX Raptor 3 schematicTook a lot of feedback from the previous post and fixed several things. This should now be properly representative to all current knowledge.As always the fullres diagram is available below 🧵
Specific updates from the last diagram include;- revising the oxygen preburner and it's location- changing the colors of some fluids to be more visibly discernable- fixing the ch4 autogen flowpath- updating and fixing spec numbers- added more labels and iconography to identify smaller features- added the powerhead regen channels (as far as we know)- replaced the helium spinstart with nitrogen- cleaned up some of the intersecting flow paths between the powerhead to become more legibleThere is also a few discrepancies that are still not totally known, such as; - exactly where the ch4 autogen is coming from. it is either the outlet of the methane powerhead autogen, like depicted, traveling through the hot gas manifold, or, it is directly tapped off at the valve assembly on the transfer tube from the lower regen manifold up to the top of the lox powerhead. we do not have any legible photos of that side of the engine unfortunately so it is not able to be exactly determined- preburner ignitor type. pretty self explanatory, we don't know what exactly the ignitors for the burners are. With the way that this engine operates it is highly doubtful that it uses conventional torch ignitors anymore, however, they still need gox/ch4, via the presence of such inlets on the common umbilical- number of turbines on each powerhead. via recovered debris it seems likely that there is in-fact two turbines on both powerheads, via the size of the turboshaft coupling, but it is not confirmed. - where the ch4 powerhead regen starts. It may be directly connected to the chamber regen loop, or it may be tapped off starting at the end of the transfer tube, like depicted. The pressures/temperatures of the methane after exiting the nozzle and chamber regen is not totally known but can be roughly estimated, suggesting that it is still "cool" enough to be used in regenerative cooling. This also doubles back to the previous point of the ch4 autogen
https://twitter.com/spacex/status/1880332005084471404QuoteRaptor engines powering liftoff and landing of Super Heavy
Raptor engines powering liftoff and landing of Super Heavy
33 -> 13 -> 3It will be very difficult to get Raptor to 300 tons of thrust, but … not impossible
I wanted to note something I had never noticed before nor have I seen it mentioned. Technically probably should have put this in the Flight 7 discussion thread but that thread is currently a mess and full of ignorance. Anyways, the last photo showing the three center engines lit during the catch you can see how they move the center ring of gimballing raptors out towards the outer ring of engines. Maybe for greater gimbal capabilities of the center three without risk of bell contact?
Quote from: dabomb6608 on 01/17/2025 09:46 pmI wanted to note something I had never noticed before nor have I seen it mentioned. Technically probably should have put this in the Flight 7 discussion thread but that thread is currently a mess and full of ignorance. Anyways, the last photo showing the three center engines lit during the catch you can see how they move the center ring of gimballing raptors out towards the outer ring of engines. Maybe for greater gimbal capabilities of the center three without risk of bell contact?Don't worry, we got you covered.https://forum.nasaspaceflight.com/index.php?topic=61945.msg2657450#msg2657450
Got a couple of questions about this new updated Raptor Diagram....1. I have always assumed that raptor uses Torch Igniters...in the post its stated that now its "highly unlikely"....got me confused...are there any specific types of igniters that use Gox\GCH4 and are better suited for raptor operation? 2. As i remember it was always assumed that Fuel preburner has two zones (Combustion\Fuel remixing), this diagram coincides with those assumptions. What preburner type is used on the oxygen side? (In the diagram it looks like a single zone one, why? Wouldn't it lead to some combustion instabilities or ignition difficulties?) [Oxygen powerpack is surely the most confusing part of this engine...]3. What type of injectors for the preburners? (For fuel one i assume its either coaxial swirl of shear ones with oxidizer going through the annular gap and fuel going through the center....but what for oxidizer preburner? I Highly doubt its any type of coaxial cause there is just no room for them there....or i am terrible at imagining things in my head))Thanks for any answers...
Quote from: DProp25 on 02/16/2025 11:03 amGot a couple of questions about this new updated Raptor Diagram....1. I have always assumed that raptor uses Torch Igniters...in the post its stated that now its "highly unlikely"....got me confused...are there any specific types of igniters that use Gox\GCH4 and are better suited for raptor operation? 2. As i remember it was always assumed that Fuel preburner has two zones (Combustion\Fuel remixing), this diagram coincides with those assumptions. What preburner type is used on the oxygen side? (In the diagram it looks like a single zone one, why? Wouldn't it lead to some combustion instabilities or ignition difficulties?) [Oxygen powerpack is surely the most confusing part of this engine...]3. What type of injectors for the preburners? (For fuel one i assume its either coaxial swirl of shear ones with oxidizer going through the annular gap and fuel going through the center....but what for oxidizer preburner? I Highly doubt its any type of coaxial cause there is just no room for them there....or i am terrible at imagining things in my head))Thanks for any answers...I'm not your best source but I'll take a stab at #1.Rap1 had main combustion chamber igniters. Rap2 does not. AIUI the propellant mix auto ignites at the temp & pressure of the MCC. The preburners probably have igniters of some type but that is conjecture on my part. Maybe someone else will chime in.
Quote from: OTV Booster on 02/24/2025 10:57 pmQuote from: DProp25 on 02/16/2025 11:03 amGot a couple of questions about this new updated Raptor Diagram....1. I have always assumed that raptor uses Torch Igniters...in the post its stated that now its "highly unlikely"....got me confused...are there any specific types of igniters that use Gox\GCH4 and are better suited for raptor operation? 2. As i remember it was always assumed that Fuel preburner has two zones (Combustion\Fuel remixing), this diagram coincides with those assumptions. What preburner type is used on the oxygen side? (In the diagram it looks like a single zone one, why? Wouldn't it lead to some combustion instabilities or ignition difficulties?) [Oxygen powerpack is surely the most confusing part of this engine...]3. What type of injectors for the preburners? (For fuel one i assume its either coaxial swirl of shear ones with oxidizer going through the annular gap and fuel going through the center....but what for oxidizer preburner? I Highly doubt its any type of coaxial cause there is just no room for them there....or i am terrible at imagining things in my head))Thanks for any answers...I'm not your best source but I'll take a stab at #1.Rap1 had main combustion chamber igniters. Rap2 does not. AIUI the propellant mix auto ignites at the temp & pressure of the MCC. The preburners probably have igniters of some type but that is conjecture on my part. Maybe someone else will chime in.Correct according to the discussions on this thread. The preburners def. have an igniter.
R2 has torch igniters on the preburners; you can see them on the side. The spots on the chamber that used to have them no longer do. I have no idea what R3 is doing, but whatever it is is going to be weird based on hints I have heard.On #2/3, I know there were some test prints for a weird fractal tree spray nozzle thing that I am pretty sure was for a fuel preburner injector. I doubt something like that would work on the ox side though, so who knows what they use there. That test print was also old and pulled out of a dumpster, so who knows how accurate it was/is.
Quote from: Gliderflyer on 02/24/2025 11:58 pmR2 has torch igniters on the preburners; you can see them on the side. The spots on the chamber that used to have them no longer do. I have no idea what R3 is doing, but whatever it is is going to be weird based on hints I have heard.On #2/3, I know there were some test prints for a weird fractal tree spray nozzle thing that I am pretty sure was for a fuel preburner injector. I doubt something like that would work on the ox side though, so who knows what they use there. That test print was also old and pulled out of a dumpster, so who knows how accurate it was/is.Am I reading this right? Someone is dumpster diving SpaceX?
Quote from: OTV Booster on 02/25/2025 09:19 pmQuote from: Gliderflyer on 02/24/2025 11:58 pmR2 has torch igniters on the preburners; you can see them on the side. The spots on the chamber that used to have them no longer do. I have no idea what R3 is doing, but whatever it is is going to be weird based on hints I have heard.On #2/3, I know there were some test prints for a weird fractal tree spray nozzle thing that I am pretty sure was for a fuel preburner injector. I doubt something like that would work on the ox side though, so who knows what they use there. That test print was also old and pulled out of a dumpster, so who knows how accurate it was/is.Am I reading this right? Someone is dumpster diving SpaceX? There are some real weirdos in the business.
With a FFSC cycle is there a failure mode where combustion in one preburner stops while it continues in the other?
With a FFSC cycle is there a failure mode where combustion in one preburner stops while it continues in the other? Does that make for a non-combustible mixture in the main chamber so the engine ends up sending one of the propellants out the nozzle unburnt —essentially a pumped venting of one of the tanks?
Quote from: sdsds on 03/07/2025 08:34 amWith a FFSC cycle is there a failure mode where combustion in one preburner stops while it continues in the other?Yes, FFSC requires ignition start and be maintained in at least three separate locations: the fuel-side preburner, the oxidizer-side preburner, and the main combustion chamber. If pretty much anything goes wrong with that it's a serious problem. Orderly venting is unlikely. If the system is modern and well designed, the situation will be recognized, valves will rapidly close and the whole thing will shut down. If it is not well designed, fires and explosions are likely.FFSC has a lot of nice compensatory factors to weigh against that, but its complexity is a downside.
