wb99999999

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About wb99999999

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    Bottle Rocketeer
  1. I see. Still, it is how inoptimised the whole thing is that made me scratch my head.. I mean there're just so many compromises in the design, I'm not even sure the cost reduction and technological readiness is enough to justfy it... This thing is just so counter-intuitive, with a longer burning stage actually having lower Isp but higher fuel fraction and non-separating booster and massive dead weight... the "cost per performance" seems very grim...
  2. Your point exactly. If I'm not getting something horribly wrong, the empty mass of a solid fuel booster would exceed a similarly-sized liquid rocket assembly for quite a bit. A liquid rocket's tank is just a thin layer of usually aluminium or stainless steel, while a solid's casing have to be a lot thicker and heavier to withstand the combustion pressure, acting effectively as the combustion chamber of a liquid fuel engine. I probably played way too much RO and became alien to the idea of Moar Booster, but it is a valid point. ISRO is apparently a tightly budgeted agency...
  3. Hi everyone! I've been reading about the curiously designed ISRO vehicles lately, and here's something that deeply confuse me about the GSLV launchers: The GSLV is a 4 staged rocket (of a sort). It has 3 stages stacked in tandem and 4 strap-on boosters acting as stage 0. The thing that confuses me a great deal is how the 2 starting stages are arranged. It uses a solid S139 booster as the core which does 4.7 MN with 269s Isp, and the four strap-ons are liquid boosters which does 760 kN each with 262s Isp. So far so good for me, even the usage of a solid as the core is a bit odd, but I totally understand the design choice since it has a higher Isp and is adopted directly from PSLV along with the second stage (which justifies using the S139 as the core stage given that they don't need to develop a new interface to mate with the second stage.). However, it is the burn time and staging order that gives me trouble: not only the liquid strap-on boosters DOES NOT separate from the core (still okay for me, the Russian Angara had considered a similar staging choice), it has a whole minute longer burn time than the core. It doesn't make any sense to me. From my understanding, the last bit of fuel in a stage is the "best" fuel, since the fuel are only pushing the higher stage and payload, without pushing on a lot of yet unused fuel. But for this vehicle, the last 60 second of the boosters' fuel is literally pushing an empty, heavy solid rocket casing. If one consider the liquid boosters probably have a higher fuel fraction than the solid core, it comes out even worse. An analog that came to my mind is an Ariane 5 that does not throw away the solid booster after they has burnt out... The point is, judging from the numbers, it seems to me that it is so OVERWHELMINGLY beneficial to at least jettison at least something for the first stage, even at the cost of complexity and some perhaps costly redesign. In my opinion, at this point the staging has gone beyond sub-optimal and entering the realm of counter productivity: the performance that the vehicle will gain from a better staging would be very large and this is exactly what they did for GSLV Mk3. The Mk3 uses a Titan style staging by the way, where strap-on boosters are ignited on the ground, and the core stage is only ignited after the booster separation. So it follows that there has to be some reason that forced ISRO to opt for such a design. Could any of you friendly folks give me some insight on this?
  4. Unfortunately these were not included in the default RO config to start with. Otherwise it would be very easy to copy and paste, even for a dumb person like me...
  5. Would it be possible to get configs for HG-3 or J-2 Sea Level? I know one can always make a config for himself, but I feel like leaving this to the pros especially since these are non-production models and the parameter are to be researched.
  6. Thanks for the advises! In fact, this was exactly what I've been doing with the config: I changed only the type of the plume and nothing else. However, both of my attempt resulted in malfunction, with the first one resulting the two exhaust ports having no plume nor flare whatsoever, and the second one resulting both main nozzle and the exhaust ports having no plume and flare. simply changing the plume type seems to mess with the setup somehow... Also, my point of using Kerolox plume is largely based on the fact that real life RS-68 has an ablative nozzle, which produces a yellowish-red "dirty" plume with carbon and other heavier molecule, instead of a clean, blue water vapor often seen in SSME and the likes. It kinda looks like the Soyuz's plume if you look carefully...
  7. First I have to say that these engine models are BEAUTIFUL!!! Secondly, how does the exhaust port real plume config work on engines like RS-68? I was messing around in the file trying to get this engine run the Kerolox plume for a more realistic aesthetics, but whatever I change seems always break the whole thing and cause the main plume, the exhaust port plume, and sometimes both to malfunction and fails... I understand that there's a bit more in this multi-plume config than the usual real plume ones. Can I get some hint/tips from you guys?
  8. Not sure if RemoteTech is what you're looking for. It has everything from delays to antenna pointing. Personally I consider it being one of the most difficult and complex component in RO...
  9. It seems to me that those stretchy SRBs in PP gimbals only in one plane (the nozzle only swivel in one axis). I checked the config file, but there's nothing indicating such behavior: the config simply quotes "ModuleGimbal" and how many degrees it can gimbal. I then went to check the config for a liquid engine, and as far as I can tell it is the same ModuleGimbal with basically nothing different... how comes it only gimbals in one plane? What can I do to make it does both plane?
  10. The thing about RSS launch is that the vast majority of time was spent out of atmosphere and gaining horizontal velocity. An orbital launch from Earth takes about 9.6 km/s, and when you're at 120 km altitude where atmosphere is basically nothing, you usually only spent something like 3 to 4 km/s and are at about 2 to 3 km/s speed. The gravity turn part is mostly done at this point, and what one should do is to burn almost perpendicular to the surface for the rest of the launch, while pitch up a little according to TWR to keep vertical velocity at around 0 or slightly positive. This phase of launch takes so much more time and fuel in RSS when compared to stock...
  11. and this is exactly what happens in RSS... typically you'll end up with a lower stage that burn out at 4G and a upper stage that only do half a G or so at the start and burn for 10 minutes up.
  12. Thanks for the advises! GT sounds like a worthy alternative, but the fact it uses throttle rather than attitude to control the trajectory leave me a bit concerned: as you guys might know many engines in RO don't throttle AT ALL... and it feels rather unauthentic to throttle my engine cluster to like 5% during the launch (at least when I'm using RO or RF in RSS). Still I will try GT. Nice idea, but I found it adding a bit of dead weight, and is not very necessary when say, manually adjusting pitch angle during the final insertion could achieve an ideal apogee at 200+ km and perigee at something like 100 km (which is high enough so that the payload or upper stage will only need to burn for 40~120 m/s to circularize, but low enough so the second or third stage will fall back and burn up). This is entirely doable manually, but involves staring painfully at orbital parameters and velocity displays and carefully tapping W and A for about 3 minute. It's just a huge hassle where an automated system would do 100x better.
  13. I play a lot of RSS, both with and without RO. One thing that has been bothering me for a while is that the auto ascent trajectory used by MechJeb is rather primitive: it dumbly follows the parabola preset, and never correct for those low TWR upper stages frequently used in RSS. So would there ever be a "smart" ascent program, whether from MechJeb or not, do the leg work of fine tuning pitch trajectory for a RSS launch? For example a smart ascent would automatically adjust pitch angle to maintain a constant 1G downward thrust once it reaches a set Apogee; it would also "depresses" the final Perigee of the upper stage so that after separation of the payload, the spent stage will fall back into atmosphere. Or maybe something would do a dogleg to reach desired inclination since MJ is terrible at high latitude launches... I might be using the MJ wrong... in that case feel free to point me out and laugh at me but still, any ideas?
  14. Question: How would Heat Pumps interact with Real Heat?
  15. I just found a couple of oversights, and here's my discoveries. PS: I have to apologize in advance that since I really don't know anything at all about modding and confiscating parts, my terminology might be very wrong or stupid. What I found when fiddling around the files is that the NTRuseLF patch has a few typos and misquotes in its config resulting some engines from supported mods still using LqdHydrogen after applying the patch. Namely, the Fat Mun (NERVAB in the config file) from Lack's SXT had a typo and becomes NERVB (naturally the it doesn't work properly). In the section dedicated for Atomic Age, the config misquotes the module used for KANDL engine and LightBulb engine, quoting ModuleEngines when those engines actually should be using ModuleEnginesFX. I don't really know what to do with them other than putting it here to help those who know what they're doing...