FYI: It is, much cheaper and faster to develop than alternatives, uses existing knowledge-bases and infrastructure, weight is minimal, drag is reduced and it looks goooood (something engineers often forget is important).
Quote from: Propylox on 08/02/2017 06:26 pm FYI: It is, much cheaper and faster to develop than alternatives, uses existing knowledge-bases and infrastructure, weight is minimal, drag is reduced and it looks goooood (something engineers often forget is important).not one of those is true. And it certainly does not looks good.
I know it doesn't appear on the Delta IV and it don't think it flies with a Delta without any SRMs, so only the M+,
A. There is no changing the 68 just for SLS. It negates the benefit of sharing the same production line and flight history.b. Obviously, you didn't know that the boat tail didn't work on Delta IV so how do you know it is viable for this kludge. c. There still is radiant effect from boat tail to nozzled. The large mass this huge boat tail is another strike against the "benefits" of the RS.e. and there is the fore mentioned ISP issue that makes the core tanks too big.
a- No significant changes to 68's and certainly not any to effect their immaculate record. As mentioned the primary alterations are lengthening the GG exhaust and piping the purge lines to outside the boattail - so it doesn't explode upon ignition. A possibility is to remove, rather than simply disable roll control, and added ablative on the bottom few inches of the nozzle just in case.b- DIV never shielded the nozzle and never introduced airflow inside the boattail as I've done. As mentioned the boattail extends below the nozzle with enough room for articulation. The space between the boattail and nozzle immediately develops a vacuum which is filled by the inlets beside the thrust structure, creating airflow.d- Define "large". It's more than zero and adds to an already heavy engine, but that's irrelevant when compared to alternatives (PoR) it actually increases performance of the rocket, its safety, reliability, while reducing cost and development. Forest from the trees.e- Love the pic and your experience actually building rockets, but a designer you're not. F. Reducing the core mass, G.I'd appreciate your input on Michoud's minor modifications necessary to build an H. actually functional SHLV.i. 6barrel core+68s+J-2X
I have nothing to do with Michoud or SLS design/production
Exactly, Forest from the trees. This design is irrelevant. POR is what it is.
The program of record - SLS with it's design and mission decisions - is the tree.
If something better comes along,
Quote from: mike robel on 08/08/2017 06:50 pmI know it doesn't appear on the Delta IV and it don't think it flies with a Delta without any SRMs, so only the M+,But it doesn't appear on most M+ launches, it seems (see image with 4 SRBs), so that's why I'm wondering if it is a something that was only used for the first few launches.(The only launch images that show the skirt/boattail appear to be from the GOES-N launch, although it could be present in some others - difficult to see in the glare of the SRBs)
It'd be interesting to know more about this skirt and the reasons for its original inclusion and eventual deletion, but thats moving kind of off-topic for this thread.
Quote from: Lars-J on 08/08/2017 06:59 pmQuote from: mike robel on 08/08/2017 06:50 pmI know it doesn't appear on the Delta IV and it don't think it flies with a Delta without any SRMs, so only the M+,But it doesn't appear on most M+ launches, it seems (see image with 4 SRBs), so that's why I'm wondering if it is a something that was only used for the first few launches.(The only launch images that show the skirt/boattail appear to be from the GOES-N launch, although it could be present in some others - difficult to see in the glare of the SRBs)I actually noticed this a bit ago while building the CG Delta IV, and asked Tory Bruno on twitter who referred me to ULA's official account. Apparently it was an aero skirt that was only flown three times:https://twitter.com/ulalaunch/status/811049041534603265It'd be interesting to know more about this skirt and the reasons for its original inclusion and eventual deletion, but thats moving kind of off-topic for this thread.
Propylox, I would appreciate it if you would stop beating a dead horse.It is as Jim states, RS-25 or bust for SLS and RL-10 for US. If you want to discuss this further, please create a dedicated thread for that hypothetical as it has nothing to do with the POR.
The only "dead horse" here is the assertion that the PoR is infallible, the best, set in stone, and unquestionable!
The only "dead horse" here is the assertion that the PoR is infallible, the best, set in stone, and unquestionable! without addressing why it's so bad, why better options aren't being pursued, what those better options are, and why asking these valid questions in the dedicated thread is riling feathers without providing valid answers.(Plus the contrary, grumpy assertion that SLS and any alternative will be cancelled, so don't talk about them).
"There isn't going to be any SLS alternative."I disagree, depending on your definition of alternative.