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arq

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Everything posted by arq

  1. Design TWR to start around 1.7, as fuel burns it will increase. You actually want a TWR of ~2 (not much higher or lower) for the first 10km, and 1.7 usually will split that relatively well. After that, it matters less (often times my last 1000m/s to orbit happen with TWR<1), but higher is slightly better.
  2. Gravity assists can be used to move around the system on fumes. I haven't done much between planets, but I've gone all over the Jool system (planets work the same, it's just a bigger scale) using them. Also, a few times my Munlanders didn't quite have enough dV to get back to Kerbin so I burned to escape Mun's SOI, then with a few assists off of Mun I was able to get my peri back into Kerbin's atmo.
  3. Ion engines have terrible TWR (especially once you count solar panels), so burns take forever. I sent a probe to mess around in the Jool system for awhile. It was fun grav-assisting between moons on tiny bits of fuel, but then I decided to head for Eeloo and then back home and that took forever. Ions are nice when ships are too small for LV-Ns, but I can usually get plenty of dV for such small probes out of some tiny tanks and an LV-1 or a 48-7s, with abundant thrust. I mean, once you break into interplanetary space, do you really need 14km/s of dV? I prefer the chemical rockets because I don't have any form of autopilot installed and it makes burns much more bearable.
  4. The turbojets can technically go up to nearly 2400m/s, though thrust starts falling rapidly above 2000m/s (but at this point it hardly matters because your throttle is so low because of the thin air). But this is nearly impossible to do below about 45km. Your plane is rather big. It would be easier for you if you started with something smaller. Also, I think you have more fuel than you really need.
  5. Max speed is based on intake/mass ratio, assuming that you can get up high enough to hit flameout. More intakes means flying higher, which means less drag and flying faster. Reading the 'intake air' stat is imprecise for the entire vessel and especially so for individual intakes. As others have suggested, the ram intakes are the best option. People like to clip them together in long lines of alternating intakes and cubic struts.
  6. Two-body physics with the large-mass approximation (your craft is considered massless with respect to the celestial bodies) are modeled in KSP.
  7. This item commemorates the victory of struts over physics in Autumn 162. You could look into Ferram's Kerbal Joint Re-enforcement if you wanted to go bigger with less struts. But I'm sure it would kill the sport...
  8. I just did an experiment. I placed a ship in 75x75km LKO with 3837m/s of dV in the tank (57s at max thrust). I waited for MM:SS MET, put the nose 10deg below the horizon, locked SAS, and burned at XX% thrust until empty. I picked the times and angles so that I would be exiting Kerbin almost exactly retrograde (and verified this after the burn). I then recorded the Kerbol periapsis after the burn. Here are the results of my two trials: 17:00 start @ 20% power - Kerbol peri 1.363Gm 18:00 start @ 100% power - Kerbol peri 1.194Gm Placing a maneuver node shortly after the fast burn, it required about 180m/s to slow down to match the peri of the slow burn. So a TWR difference of a factor of 5 (a huge difference) made a difference of ~4.5% on the net dV. This experiment was imprecise, but should give ballpark results showing that TWR does have a small effect on net dV.
  9. TWR does have a small effect on transfer range because of the Oberth effect. It is a 'force multiplier' for burning close to periapsis (and some other places, but relating to TWR this is the most relevant). So a craft with a TWR of 2 can make better use of the Oberth effect than a craft with a TWR of 1, which means that if both have 5000m/s of dV then the higher TWR one can go slightly further. This effect can be somewhat mitigated by 'periapsis kicks,' but Jool is 1900m/s from LKO and by the time you burn half of that you're on escape which obviously prevents any additional kicks, meaning you must finish the burn no matter how long it takes. Still, excepting extreme cases the effect of low TWR is very small (tens of m/s, likely) and the bigger consideration is your sanity. But high TWRs do make landing and ascending from surfaces more efficient. So remember that if you plan on landing somewhere, dV isn't the only concern.
  10. Scott Manley did a guide recently (watch the earlier segments if necessary, this is part 3)
  11. To go faster with jets, you must go higher to thin the air. If you can't fly higher without flaming out and have pretty much capped in speed, you should switch to rockets. If that's too low/slow, you need more intakes. As soon as you need to start throttling back the engines, you are in the AIR-LIMITED regime. At this point, your max thrust is proportional to air intake, not the number of engines (in fact, more engines hurt because they add mass which adds drag). Of course, at some point you enter the realm of 'air hogging', which many players consider to be 'cheating' (enough intakes makes getting to orbit trivial), so do what you find 'fun'.
  12. You could add a tail plane behind the craft. Some stabilizers further back from the CoM would help to keep it flying forward. Your near-complete lack of vertical stabilizers is doing you no favors on this plane.
  13. You could place one set in 2x symmetry (or whatever you want), then use <alt> to copy the parts and paste them as many other places as you wish. It's slightly less elegant than what you want, but I believe it is the best solution the game currently offers.
  14. In stock, I usually just keep adding stages to keep the TWR ~1.7 (except for the last 1000m/s I can go lower) until I hit the necessary dV. I haven't played with asparagus in FAR enough to have a good sense for doing it there - the lower dV to orbit has prevented me from really needing it yet.
  15. Eve would be good for some preliminary assists, but it has a higher orbit so you would want to do the later assists off Moho. Also, for the first pass by Eve, aerobraking (but do *not* capture) could also help.
  16. Mun won't be of much help in an assist to LSO. It is generally worth less than 100m/s. Your biggest asset here will be Moho. By repeatedly getting gravity assists from Moho, you can get down into a orbit that goes between Moho and LSO. From there, you must burn at LSO to circularize.
  17. As the others are suggesting, the total dV (and even fuel) cost will be the same, assuming you use the same TWR on each stage. If you put the two together but only add engines for one, it will actually be cheaper because of the lower engine mass (though equivalent to if you had only used half the engines on each payload). dV is agnostic to scale, it depends only on fuel fraction and ISP.
  18. I'm sure that when money is added to the game as a significant gameplay element, there will be something to deal with this situation. For now, since it makes no difference in-game, just imagine that the SRB's are recovered successfully after they go down with chutes.
  19. Also, 2.2 is too high in atmo. It's true that you need roughly 2.2 to maintain terminal velocity all the way up, but remember that TWR increases as you burn fuel. 1.7-1.8 is plenty high for the beginning of stages, typically when I build for that I get around 2.3 by the end of each stage.
  20. If the info readouts are all you want, try Kerbal Engineer Redux instead. It doesn't have autopilot functionality.
  21. e^x = sum_{n=0}^<infinity> (x^n)/n! so e = 1/0! + 1/1! + 1/2! + 1/3! + 1/4!... = 1 + 1 + 1/2 + 1/6 + 1/24... = 2.71828 Anything more than a 4-function calculator will have this function (and the natural logarithm) built in. For KSP, the logarithm (which is the inverse function of the exponential) is much more important exp(log(x)) = x Some calculators use log() for the natural logarithm and some use ln(). If log() is not the natural logarithm, it is the 'common' logarithm (base 10 instead of base e).
  22. These are silly threads. Even the devs won't be certain they won't need to break saves until well into the QA phase.
  23. As the others are suggesting, burn so that your apo is out around Minmus. Make sure that your apoapsis is at/near the ascending/descending node of your target. At the AN/DN out near Minmus, change your orbit to whatever inclination you want, then drop your periapsis down into the atmo a little (maybe 35km? i dont remember) so that it will bring your apo back down.
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