TimothyC

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  1. This is correct behavior. The BDB dll has basic cryogenic functionality integrated independent of Nertea's work.
  2. I would note that while launched in May of 1973, S-II-513 (the second stage of the rocket that launched the station) was on orbit until 11 January 1975. This does mean that the S-II stage was in orbit for nearly 11 months after the last crew came home. Because the S-II was lighter (probably around 40 tons following the stage being inerted) than Skylab, and had a more consistent cross section for drag to act on. Skylab was maintained in a solar-inertial (so that the solar arrays always pointed toward the sun) mode while in operation, left to switch into a gravity gradient (one end of the station always pointing toward the earth, meaning the solar panels would act as a drag break in the upper atmosphere) mode after the last crew, flown in an end-on velocity vector (IE, to present the smallest possible cross section for drag, the station was turned so that the long axis would remain parallel to the orbit at the cost of using the gyros and limited rcs prop*) when they thought they might be able to reuse the station with the shuttle, and finally back to the gravity gradient mode to accelerate and control de-orbiting when it was obvious that the Shuttle would not be able to get up in time to reboost the station. *Skylab RCS prop was GN₂ an was designed to allow the possibility of on-orbit refill, even though the station was designed with a rather short orbital life.
  3. Non-hydrogen propellants for nuclear thermal engines were considered in the 1960s as a way of retaining long-term storability on deep space missions (mostly things like Ammonia). The idea died out as the NTR programs did. However, CO₂ as a propellant for nuclear thermal engines came back under consideration starting in the early 1990s with Zubrin's work Nuclear thermal rockets using indigenous extraterrestrial propellants. This work mostly focused on Mars and Titan, but included data for all kinds of liquid fuels in NTRs. The paper does also note that a nuclear engine using a propellant that is an oxidizer at high temperatures (water, carbon dioxide, ect) would have different fuel cladding needs that one that used a hydrogen based propellant (hydrogen, methane, ammonia), limiting single-engine utility for mars applications.
  4. Hello Dr. Jet. I was one of the people who brought forward to Jade data on NIMF (Nuclear rocket using Indigenous Martian Fuels). While you may be broadly correct that there are limited reasons for using Liquid CO₂ on Earth/Kerbin, the resource here is used as both a stepping stone in chemical processes, and as a fuel for nuclear engines. When using it for nuclear engines, you are going to want it as a liquid anyway, so it makes sense to simply compress it down and and store it as such, rather than freeze it, and then compress the gas that comes off when you need fuel. Furthermore, your temperatures are slightly off. Liquid CO₂ can exist between 217K and 304K while under pressure, which is not the same as maintaining it at 303K as you imply. I'd also note that as far as density goes, Liquid CO₂ is only about 30% less dense than dry ice, which makes it still workable for a lot of rocket applications (in game, the only other application is the production of methalox meaning that the difficulties in storing it are minimal relative to the added complexity of storing it as dry ice and then liquefying it on demand.
  5. Five meter-ish stages (ACES, Delta IV, Atlas Phase II, 5m DCSS, Vulcan, Ariane V core, ect) end up being ~3.125.
  6. Nope, that's Atlas. Atlas went from III to V because of the functional merging of the Atlas and Titan lines.
  7. Congrads to @CobaltWolf for being the first Rep 20k regular user [20004 as I type this] (the squad account is around 23k, but that doesn't count).
  8. I'm a bit confused here. BDB, reDIRECT, and CryoEngines/Tanks use Ox in place of LOx. Also, in the real world, non densified LOx has a specific gravity of about 1.1 (water being about 1). Liquid Hydrogen on the other hand has a specific density of 0.07. Now, you need about 5-6 times the mass of LOx that you do of LH2, but that means the LH2 tanks are still a major driving factor in the density of the entire tank system. In average rockets the specific gravity of the total prop (fuel and oxidizer) is about 0.99 for Kerolox, 0.8 for Methalox (Less dense fuel, but more Oxygen), and 0.35 for Hydrolox.
  9. The S-II and S-IC stages have the same diameter, and Cobalt desired to retain the same relative lengths between them, which precludes downsizing them. Cobalt also didn't want to mess with relative volumes (you know how the various size 1 tanks don't have a 1:1 capacity vs length relationship with each other? Cobalt/JSO wanted to avoid that). BDB (really, JSO did a lot of the balancing work) is based on using a combination of real world ISPs and thrusts based on either 25% of real world values (lifter/sea level engines), 50% of real world values (vac engines so that the upper stage burns don't last forever), or 37.5% of real world values (the J-2, because it comes in both sea level and vac versions, and it didn't make any sense for the vac version to have a higher surface thrust than the sea level one).
  10. In the beginning Cobalt said let there be a mod to fill the gap of Atlas, and lo, it was good. And Cobalt said let there be Titan and no Saturn, and lo, it was good. And the people lamented, and their cries were for Saturn. And Cobalt heard their cries, and was moved by them, and began Sarnus. And lo, when developing Sarnus, Cobalt cried out, for the game did not have hydrolox fuel support, and Cobalt was covetous of his mod, and desired not to have a dependency. And after much discussion, the decision was made to under-scale the Sarnus parts so that the Mighty F-1 engines would not need 90% of the thrust of the real engine to lift the stack. And Cobalt beheld this, and decided it was not good, and added hydrolox tankage to appease the masses, and they rejoiced for their rockets, and were grateful, until they went back to asking for Delta IV and X-20. - A Theatrical History of BDB
  11. Because it's a video by Stratzenblitz75, not Bradley Whistance.
  12. J-2S. It was the planned upgrade with slightly better performance, lower weight improved ease of manufacture, and it replaced the pressurized starting tank for the turbopump with a series of solid start cartridges (the yellow things).