ferrer

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About ferrer

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  1. I decided I would have a go at using the KSP Trajectory Optimization Tool to help me plan a manned Eve flyby (my first). My goals were to: Have a periapsis of under 400 km at Eve (to get the In Space Low science), ideally very close to the atmosphere so as to maximise the amount of time spent under 400 km, and to maximise the gravity assist Have a periapsis of 30 km at Kerbin (for re-entry) Have a mission time of roughly 1 Kerbal year Minimise delta-V costs Have short burn times to increase burn accuracy Bring back from low Eve space an EVA report, a crew report, a materials study, a goo observation, a pressure scan and a temperature scan The mission involved three burns in total: A trans-Eve injection burn while in low Kerbin orbit, to send Jeb on his way A burn at Eve periapsis, which, along with the gravity assist, set my Sun apoapsis outside the orbit of Kerbin. This increased my orbital period so that Kerbin could catch up with the ship A burn at Sun apoapsis, to achieve an encounter with Kerbin I ended up using a Poodle engine on a relatively small craft - this made the burns quite a lot more accurate than they would have been if I had used an engine with lower thrust. I was able to get a periapsis at Eve of 100 km, which gave me roughly 8 minutes in low space, plenty for doing experiments, performing EVAs, retrieving data and performing the periapsis burn. The theoretical total delta-V from low Kerbin orbit to re-entry was 1250 m/s (which I think is reasonably good?), and I actually achieved a few m/s below this. I was able to adhere to the mission plan very precisely, so the whole mission went very smoothly, and that's something that pleases me very much.
  2. I think it only seems like this because your camera stays on the small craft the whole time. It might seem like the large craft is being pushed away, but the reality is that the small craft is just rebounding, and the large craft's velocity isn't changed much.
  3. The way things behave in KSP is the same as the way they would behave in real life. Maybe you're subconsciously expecting a resistance force when you push something in KSP, but there isn't one since you're in a vacuum?
  4. Just had a look at this again and realised I'd forgotten something - should be ve (E exp(dV/ve) - 1) though like you said, that doesn't matter if your ve is the same. (Here are definitions for the various ratios, including structural coefficient, by the way.) Now if you're using drop tanks with equal structural coefficients, it results that using equal delta-V for each stage is optimal (as wumpus suggested earlier on). I ended up solving the problem numerically, the final result being the way a certain amount of delta-V should be distributed between a given number of stages so as to minimise the total mass of the spacecraft (interestingly, this turns out to be independent of payload mass, seeing as it's not part of the expression above). Not sure how useful all this is to you, but it's better written here than on some scrap paper at the bottom of my drawer
  5. A while ago, I derived the result that for optimal staging (i.e. highest overall payload ratio), ve (E exp(dV/ve) - 1) is the same for each stage (where ve is the stage's effective exhaust velocity, dV is its delta-V and E is its structural coefficient). I can't be 100% sure that it's correct, but it might be worth calculating it for each stage on your spreadsheet to see whether it matches up with what you expect.
  6. That's what I was referencing in my original post. It definitely is a bug, asteroids have previously always generated with different masses.
  7. Though I initially thought that it would be assigned, I did see the following lines in the config file: That might indicate that an actual calculation takes place, but I'm not an expert so I don't know how/whether that's used. It's already on the tracker (linked in the OP). My experiences match exactly those described in the bug report (all asteroids of all classes spawn with mass 150t), so I didn't have any information to add.
  8. I recently attempted my first-ever asteroid redirect, with an A-class asteroid that was approaching Kerbin. Rendezvous was successful, but once I was attached to the asteroid, I realised that its mass was 150 tonnes - far more than my expected maximum of 10 tonnes. I found that this is a bug that was already on the tracker (Bug #9392) - it seems that all asteroids are spawning with a mass of 150 tonnes regardless of physical dimensions. With little information available, I want to have a go at diagnosing the problem, and possibly at creating a mod to remedy it. My question is, how is the mass of an asteroid calculated? How is it dependent on class/size/shape, what algorithm is used to come up with it? I can see in the PotatoRoid part.cfg file that the default mass is 150 tonnes, so presumably something that used to happen on asteroid generation is no longer happening. (As a secondary question, have many people noticed this bug before? I feel like if it was a widespread problem I would have found more threads about it.)
  9. This seems like a great idea, and I'd be interested in hearing from modders whether there are any practical concerns that would make implementing it more difficult than it seems at first glance. I don't personally have much of a problem with using external tools to find launch windows and the like, but some people do, and I think it would be great to have a more naturalistic way of doing this in-game.
  10. My first manned Minmus landing since I started playing KSP again a couple of weeks ago. That's one small step for... Oh.
  11. I've come back to KSP for the first time since 0.23, playing in science mode (after a bit of reading up, career seems a bit too restrictive for me personally). So far I've performed multiple manned Mun and Minmus landings, sent an unmanned lander to Duna, and I'm about to do the same for Eve. One of the things I'm most pleased with, however, is this monolithic space station with fuel capacity: It was a great pleasure to design, launch, set up and rendezvous with, simple though it is.
  12. An inviscid fluid could still be compressed - compression has nothing to do with friction.
  13. The wiki says that the Puff engine has a thrust in vacuum of 20 kN and weighs 90 kg, whereas the most powerful RCS port has a thrust of only 2 kN and weighs 30 kg. What makes you say that the Puff is less powerful?