Right

Members
  • Content Count

    185
  • Joined

  • Last visited

Community Reputation

101 Excellent

1 Follower

About Right

  • Rank
    Spacecraft Engineer

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. Nice one Nefrums, I'm using a rapier for Kerbin ascent too.
  2. [quote name='HoloYolo']What is the Delta-v for the height we are launching from? Also, how do I put in the HyperEdit coordinates.[/QUOTE] We are launching from about 1km altitude, so near sea level. I had to change it from exponential to standard form. 0.000000046143, 128.299978705477 Open up ship lander, set altitude to ~1000m, copy and paste those numbers into each of the coordinate boxes. Once the planet loads, reset your altitude to ~10m.
  3. Greetings, Fun challenge! Is ISRU acceptable? Also, re-entry heat at 100% or greater right?
  4. [quote name='Red Iron Crown'][quote name='tewpie']Also the backs of engines can be used as free attachment points for axial air intakes (rotated 180 degrees and offset forward).[/QUOTE] That is fine.[/QUOTE] Well hang on a second... I thought the rules especially prohibit engine clipping. And rightly so I think. You can reduce tail drag quite a lot by unrealistically clipping tails cones on rear engine nodes. [quote name='tewpie']Ok, but clipping reversed nose cones into the backs of engines is ok? Cause that's what Val did in his entry :)[/QUOTE] I don't believe he did. He attached the "Small Nose Cone" on the back, no clipping or rotating.
  5. Greetings! Quick Q: For the low mass sub challenge, is BetterTimeWarp an acceptable mod? It adds no vessel functionality, just gives more precise control over time warping.
  6. Congrats Val! Should be no problem recovering. Tewpie, is engine stacking the same as clipping two engines on top of eachother?
  7. [quote name='Red Iron Crown']It doesn't work with cars for the reason I mentioned earlier: Cars have fixed power and variable "thrust" when at full throttle.[/QUOTE] If you're saying that one in fact doesn't save on fuel going from one hill to another by accelerating at the troughs versus the peaks, then I'll have to take issue. By power you mean? If the Oberth effect is as you described in you're linked post, then I see no reason why it would be limited to reaction engines. It is merely a side effect of kinetic energy having a quadratic growth with speed. I can't see the source of the velocity change impacting this.
  8. [quote name='Red Iron Crown']Familiar examples are hard to come by, and aren't very intuitive. The best I've come up with is...[/QUOTE] Sorry RIC, that was meant for GoSlash in looking for examples of when burning at the periapsis was not ideal. If that was what your example was intended to be however, I would say that is in fact a counter example. I like the illustration though - While driving, I used to speed up at the top of a hill to save gas getting over the next hill, but since I found KSP I know thats backwards. I now speed up at the bottom. [quote name='GoSlash27']This is also true at Duna's end. You don't necessarily want to retroburn at the lowest periapsis for the lowest DV expended. Closing your retroburn orbit will cost 616 m/sec if you do it at 60 km, but only 584 m/sec if you do it at 500 km. Above that, it gets more expensive. Of course, it costs more to orbit your vehicle at 8Mm than you save by transferring from up there, but it illustrates the point: Gravity wells work [I]against[/I] the Oberth effect, not for it (and are certainly not the cause of it). Gravity wells are valleys you have to climb out of. The Oberth effect, OTOH, is a slingshot effect that boosts your efficiency with velocity. They counteract each other. The Oberth effect is about velocity, not gravity. best, -Slashy[/QUOTE] Hmm, I don't think that example works. In both situations you named, burning at the periapsis is still optimal. I could be taking you too literally, but you said "In fact, periapsis burns are not necessarily the most effective even with Oberth effect." Also, climbing out of gravity wells is hard, yes - but it the energy lost during the climb goes down the faster you do it. And these valleys work both ways, so if you gather a bunch of energy on the down swing, and then push out and lose less energy on the way out, you've got a net gain. I concur, Oberth effect has nothing to do with gravity, but there is a different effect that - in addition to Oberth - makes periapsis burning more efficient. This one [I]is [/I]directly related to gravity. I tried to illustrate this with my black hole scenario, but that may have been a bad explanation. What did you think of it?
  9. So the Level 1 Low-Mass Sub-Challenge is stock only, right?
  10. GoSlash, Could you give me an example? I'm having trouble thinking of one outside of a few minor things. For conceptual simplicity, I think of it this way: You're passing through a friendly black hole (practically linear hyperbolic orbit). If the singularity is stationary, and you do nothing, you emerge from its SOI at the same speed you entered. Gravitational energy gained = gravitational energy lost If you burn 10d/V at the periapsis, your exit journey is a bit faster and shorter than your entrance. You emerge from the SOI with >10d/V. Gravitation energy gained > gravitation energy lost RIC, I agree. But most of my rockets' masses change significantly while burning. If that graph was in vaccum and with infinite fuel flipped on, I'd be sold.
  11. [quote name='Red Iron Crown']Have a look at a rocket stage's speed vs. time graph:[/QUOTE] Not that it invalidates your point, but that graph would happen even if you were wrong due to decreasing fuel mass and atmospheric drag.
  12. [quote name='GoSlash27']Right, I'm with RIC on this one. the Oberth effect has nothing to do with gravity wells. It's simply the result of the exponential relationship between velocity and energy. It holds true even without gravity wells. Best, -Slashy[/QUOTE] Okay I've got my terminology confused. I'm describing powered gravity assists. Strictly speaking, the Oberth effect has nothing to do with gravity. However, isn't it fair to say that the Oberth effect is not the sole reason periapsis burns are the most effective?
  13. [quote name='Red Iron Crown']That's a poor way to explain it, because the Oberth Effect also works for retrograde burns which end up spending *more* time deeper in the gravity well.[/QUOTE] As far as I can tell, the explanation fits for retrograde burns just fine. When you slow down at the periapsis, you spend more time in the gravity well subsequently, which serves to slow you down more than otherwise. I could be mistaken, I'll check out your link.
  14. In the fewest words I know how, I will venture an explanation... Gravity is a force working over time. When you increase your velocity at the periapsis, you spend less time in the gravity well (losing speed) on your way out. As per your question about the sun: its a malformed question. You're velocity hasn't actually changed that much when you leave kerbin SOI, your point of reference changed. Insert theory of relativity.