Ed, why do none of your concepts incorporate a common bulkhead for the stage tanks? These F1 based concepts would not be using shuttle tanks (no need for SRB support beam), and the upper stages would be new anyway?Is common bulkhead such an advanced concept, even though it was used as far back as Saturn V?
Here are a couple of the core-only concepts I like. These use only two engine types and no strap on boosters. - Ed Kyle
As for RP/LOX, no stage of the HLLV diameter category has ever used common bulkheads to my knowledge.
Quote from: edkyle99 on 10/05/2013 04:17 amAs for RP/LOX, no stage of the HLLV diameter category has ever used common bulkheads to my knowledge. Maybe not HLLV, but doesn't Falcon 9 have a common bulkhead? Or was that only Falcon 1?
Quote from: edkyle99 on 10/06/2013 10:26 pmHere are a couple of the core-only concepts I like. These use only two engine types and no strap on boosters. - Ed KyleThose look pretty neat. I do wonder, how much would performance change if you would swap the RL-10s and upper RS-68 by one and three J2X, respectively?
I think the problem with scrapping the SLS core and going with F-1A core(s) is that you inevitably have to replace it with a second stage that needs 3-5 J-2X. So we're back to a Saturn-like family except perhaps with multi-core configurations.We have these two hydrolox gas-generators. One is smaller than we'd prefer for a super-heavy rocket, and the other has rather disappointing specific impulse. It's enough for me to conclude: screw it, let's stick with the RS-25. Nobody else is going to use this stage anyway.
And I keep going to Atlas V, Delta IV, and Falcon 9. All three are two stage LV's that can put payload through escape to to GTO. They aren't 3 stage. And F9 uses a GG kerolox booster -and- GG kerolox 2nd stage to do it. And somehow, if SpaceX's info is to be believed. That 2-stage low-isp GG kerolox F9v1.1 can still get right about the same payload to GTO as the high ISP Atlas V or Delta IV. So they're doing -something- there. I'm just trying to pull on that thread a little here.
There's a Boeing AIAA paper out as of about a month ago."The Space Launch System Capabilities with a New Large Upper Stage"I can't post it as it was shared with be with the instructions not to post it.But, I did list some performances above (I'm hoping that is ok. :-) )It lists performance for Block 1, and the three Block 1B configurations, four RL-10's, two MB-60's, and one J2X.I notice your numbers for Block 1, and Block 1B with four RL-10's to LEO and escape in your drawing.Per the Boeing paper?LEO: Block 1: LEO: 70mt TLI: 24mtBlock 1B (with four RL-10's) LEO: 93.1mtTLI: 39.1mtThose are a little less than you are showing for Block 1 and 1B to LEO and Escape. I think Escape is usually less mass than TLI?Just just thought I'd mention that. Are your numbers for Block 1 and 1B a little high? (I have no idea myself)Not sure, but I'm guessing that Block 1 will actually be closer to 70mt, despite what the ESAS report was saying for that same LV. Probably due to the core being several mt heavier than ESAS was assuming?And I think the 5-seg SRB's in the ESAS LV 26/27 were assumed to have HTPB rather than PBAN (ESAS page 426).SLS vs. LV 26/27 will have less energetic PBAN and have a heavier core. Thus I think it'll be closer to 70mt, than the 90-100mt that LV 26/27 were to have.And I'm assuming the ICPS would do little or no ascent on a Block 1 SLS, and basically be a payload. Just do the circ burn. Where with Block 1B, I think the DUUS does some of the ascent. (with propellant offload if the payload is only going to LEO, and to BLEO. For optimal LEO performance).
I'm starting to doubt the "SLS is at least 90 metric tons" claim too. I tried the numbers for SLS from the Boeing alternative SLS Architecture document on L2 on the Schilling calculator. I got a payload barely over 70 tons with a 7000 kg LAS jettisoned after 330 seconds. However, on an L2 thread one of the SLS engineers (I think he was, anyway) claimed that the empty mass without residuals was actually closer to 102 tons rather than the 115 tons claimed in the Boeing paper; using that value kicks up the LEO payload to almost 90 tons again. He also claimed that 115 tons was closer to the Block II core, with an extra RS-25 and support core Advanced Boosters. So I'd say there are three possibilities: 1. The 115 ton figure is for a strengthened version of the core that can support advanced boosters and an extra engine and the real Block 1 can actually lift 90 tons.2. The guy was completely wrong and Boeing is right, and real payload is just a meager 70 tons.3. Boeing is in some kind of political conspiracy to prevent the real payload from leaking out so they added 13 tons to the dry mass to give a 70 ton payload for anyone trying to check it. It's probably number 1, at least I hope so.
Also, could you maybe give us the payloads for the other two variants?
I think a J-130 core would not have been able to support an upper stage big enough to reach the 130 ton mandate.
The Block 1 core in it's current form probably can't either, but the heavier core designs that result in 70 ton payload estimates can.
They are designed to take much more stress from advanced boosters, a fifth RS-25 and a large J-2X upper stage and/or a DUUS with a 130 metric ton payload. The initial Block 1 core isn't adapted to these things, only for a DUUS, and could still lift about 90 tons to LEO.
The later Blocks would have a much heavier core stage though, and any "Block 1" that will fly after this core design has been taken into service will likely use the much heavier Block 2 core for increased commonality, reducing payloads with standard boosters to 70 tons.At least, that makes sense to me. I think.