By the way, I started this thread because I didn't see one about Raptor,
I realize that SpaceX still has not released any details regarding the potential Raptor Upper Stage they seem to be developing (other than specifying LH2 and LOX as propellant) but it seems like it will probably be comparable to the Centaur US (possibly boosting F9's performance to ~30,000 lbs). My guess is that they'll try and use the simplest hydrolox engine design they can get away with. I expect to see something similar in performance to the RL-10B-2 (~24,000 lbs thrust, used on Delta IV second stage). I think the reliability and high efficiency of a closed-loop expander cycle would make sense.
Quote from: Horace Grumpford on 08/28/2010 09:40 pmI realize that SpaceX still has not released any details regarding the potential Raptor Upper Stage they seem to be developing (other than specifying LH2 and LOX as propellant) but it seems like it will probably be comparable to the Centaur US (possibly boosting F9's performance to ~30,000 lbs). My guess is that they'll try and use the simplest hydrolox engine design they can get away with. I expect to see something similar in performance to the RL-10B-2 (~24,000 lbs thrust, used on Delta IV second stage). I think the reliability and high efficiency of a closed-loop expander cycle would make sense.From the information SpaceX has released, it appears the Raptor engine will be a staged combustion design quite a lot more powerful than the RL10, with an Isp of 470 seconds--a very advanced design.
Who's existing tooling? Boeing is not likely to be building the upper stage for SpaceX.
I looked on the forums mentined above and 150,000 lbs of thrust seems like it might be just a tetch enormous. It would pretty much make Falcon 9 the only rocket in the world (I think) to put the least powerful stage in the middle of the stack.
Though, I would not be surprised if SpaceX decided to push the envelope and went with a common bulkhead design... That would look more "Centaur" like.
Quote from: kevin-rf on 08/30/2010 02:24 pmThough, I would not be surprised if SpaceX decided to push the envelope and went with a common bulkhead design... That would look more "Centaur" like.My understanding is that all SpaceX tanks so far have been common bulkhead. The more demanding thermal characteristics of LH2 may make the common bulkhead more challenging (MSFC would not attempt it for the Ares upper stages), but SpaceX already has the kerolox common bulkhead worked out.
That makes so much more sense. I thought it was going to be a third stage. And what do you mean by Merlin-1e? Is that simply the name for the vacuum Merlin, or a soon-to-be Merlin-1c replacement?
Merlin-1e is the vacuum version of the Merlin (it has some differences to the core stage version). The new core version of Merlin is known as Merlin-1d.
There seems to be different categories of projects:Category 1) There is the official trumpeted stuff (come buy expendable launches (F9 or FH) from the Cape or Vandenberg). Catergory 2) There is the quieter stuff but still out there (dragonlab, larger PLF available*, propulsive landing)Category 3) Then there is the stuff that seems to be in the weeds (Merlin 2, raptor stage, Texas launch site, Superheavy lift, reusability, making life multi-planetary) but might come to the limelight soon. Do you think that the Category 3 type stuff will be announced one at a time, or mostly at the same time? Will it be before the IPO, during the IPO process, or after the IPO?Any predictions for when the raptor stage is officially on the list of available choices?