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rcp27

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About rcp27

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    Spacecraft Engineer

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  1. A major challenge for designing low cost staged launchers is the cost of staging itself. You might think that a Reliant and FL-T800 fuel tank makes an efficient lower stage for a small launcher, and in mass/fuel efficiency terms, it is. If you add in the cost of decoupling it, though, the balance goes in a funny direction. A Reliant and a dry FL-T800 tank combined weigh 1.75 T. A TR-18A stack decoupler, while only weighing 0.05 T, seems a convenient way to stage it off to allow a lighter, more efficient upper stage. That coupler, though, costs 400. If you look at the kind of cost-to-orbi
  2. Fuel for the plane (not counting the orbiter's tank) is 270. While getting confused about some odd cost numbers, I have now noticed that it appears the fairing itself, not just the "base" has a cost associated with it. For example a Hammer costs 400, a fairing base 300 and a tiny decoupler 300, so you would expect the cost of the rocket in my earlier post to go down by 1000 if I remove those (those being the "lifer costs". In fact it goes down by 1038 because that's the cost of the fairing itself. So call the cost-of-launch (assuming I can figure out how to recover the plane) about 310 (it
  3. Same old Ant. I have a suspicion that the Ant may have its physics modelled as if it did have a fairing even if one doesn't show. For the sake of completeness, I thought I'd see if I could do any better in the SPH. I knocked together this little spaceplane That thing in the middle is a diverterless intake that also holds liquid fuel for the whiplash, and there are a pair of Sparks each with 3 Oscar Bs on the sides. The payload, at the front, is the same orbiter as before, still with its ant and single oscar B. I couldn't get the plane to orbit, but I achieved a suborbital
  4. My understanding is the radial battery, like the thermometer, just adds its mass to the part it's attached to, so doesn't unbalance the craft. It's inside the fairing (just), so doesn't have any aerodynamic issues. And it contains enough charge to transmit the all important science even on the night side of Kerbin. I've had a bit of a play around, and I think the key issue is the step from 0.625 m parts to the 1.25 m Hammer. I just launched a satellite using the 1.25 to 0.625 m structural part and a 0.625 m nose cone instead of a fairing. While the radial battery is OK from a mass dis
  5. By the time the fins burned off the craft was flying in a straight line anyway, and as they were attached to the discarded booster, they aren't really that important. Right, just built a HECS, 1 Oscar B, 1 Ant, 1 Z-100 Battery, 1 Communotron 16 and 2 OS-Stat solar panels craft and put it on a Hammer under a fairing with a TR-2V decoupler and achieved orbit. Mine only cost 3298. The experienced KSP players will be shouting at their computers "fix your staging!" around about now. So the question is why did this work when my earlier
  6. The problem with this analysis is it doesn't consider actually getting out of the atmosphere. If you go with a single SRB as a launch stage, you have to accept it's sub-optimal burn profile (constant thrust until the fuel is gone) and the need to get out of the thermally and aerodynamically challenging part of the atmosphere. I haven't chosen the Thumper for either it's thrust or it's dV, but for the fact that it can get out of the lower atmosphere. I've just had a go at a basic test: I put a HECS probe core on a Hammer, nothing else. That was a total failure: it's aerodynamically unstable
  7. I'm home from work now and have re-created this launcher and flown a test flight. There is so much wrong with this particular launcher that it is borderline un-flyable. Anything approaching an efficient flight profile is just not happening. The first issue is that, while the Thumper can get this load out of the atmosphere, you don't have enough margin to do a very effective gravity turn. In the event, though, that's not much a problem. The real problem comes from the Ant. It gives a new definition to "feeble". The burn time required to get any kind of useful dV is insane. If you
  8. I haven't done any detailed study, but for small payloads to LKO my feeling is that for minimizing cost with a disposable launch system, a system based on an SRB is the way to go. I've made serious money on LKO career contracts using a QBE core, a couple of solar panels, a communotron 16, 0.975 inline battery and reaction wheel as the payload, with an ant and 3 oscar Bs as an orbital engine on a 0.975 m decoupled, on top of a 1.25 m fairing, Thumper SRB with three basic fins and a launch clamp. For that king of payload, the cost to orbit isn't that far off the fuel burn alone for an SSTO capab
  9. One of the features I have always found a little frustrating is the lack of science from space. There are tons of biomes on planets, and a few biome specific experiments in low orbit, but mostly we just have space low and space high. I find there's a bit of a science drought between getting to Kerbin orbit and landing on Mun, after which science comes in huge quantities. Given that satellite contracts are offered differentiating things like equatorial, retrograde, polar, tundra and Molnya orbits, it seems to me there might be an interesting way of making actual space flight worthwhile beyond b
  10. I have my fair share of "Commsat" variants, as well as usually having a KSS. The other name I frequently use is "Moho" for my first ship to orbit as a nod to the Mercury program.
  11. Presumably if you turn cross feed off and use fuel lines you can do asparagus the old fashioned way? I prefer to eat my words with fava beans and a nice chianti
  12. Yeah, but that is such a massive improvement, I don't think it counts as a "little thing". I have years of muscle memory to unlearn now. When I launch my fingers just automatically hit T-Z-M. It'll take many launches before I can unlearn the M.
  13. We've all read about the "big news" features in 1.2, things like communications net and balanced fuel flow. How about the little things? What new features have you found that you have noticed that make life a little easier? for me it's "When a Kerbal plants a flag, credit is given to all landed/splashed Kerbals in physics range. Prevents the need to have flag-planting parties with large crews."
  14. A good suggestion. I've also found problems with planes being uncontrollable on the ground when the undercarriage is not strong enough for the weight of the plane.
  15. I've encountered this problem when the wheels aren't quite straight. In the SPH, select the rotate tool, set rotation to absolute and make sure angle snap is on. Give them a wiggle and make sure they're set so the wheels are vertical and aligned axially with the plane. Most times that fixes the problem.
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