Streetwind

That may have been because you chose a symmetric second layout. And in that layout, despite the fact that the reaction wheels are far away from the center of mass, the center of torque is still exactly congruent with the center of mass. Both setups are basically identical, and as such, it's no surprise that the results are identical. Try again with: - both reaction wheels where the above screenshot shows one, and none elsewhere - both reaction wheels at the far end of a single tank, and none elsewhere This will contrast a case where the center of torque is close to the center of mass with a case where it is well away from the center of mass. This should result in a very noticable difference - unless placement truly does not matter.

I was worried about that at first as well. However, I found that if a part blocks fuel flow, it generally states so in its stats window (true for all stock parts, your mod experience may vary) in easy to see orange text. See a decoupler for reference. My main workhorse rocket has used a quadcoupler with engines for a long time now, works quite beautifully. Not as much thrust as a mainsail, but the fuel efficiency is much better.

Why not simply go for the quadcoupler or quad adapter? Should be under structural parts. Will give you 4 mid-sized mounting points below a large-sized one. If you play Career you need to research them first. The quadcoupler is somewhere in the middle of the tech tree, and the quad adapter near the end.

Maybe the term was applied loosely, but the point was to illustrate the difference between hovering and being in an orbit. In the latter case you are being helped by the celestial body's gravity because it maintains your trajectory for you indefinitely, for free. Thus by burning for escape out of an orbit, you can apply the full power of your engines to that goal, while the directly ascending vessel can only apply that portion which isn't spent on hovering. The result is exactly the same as a gravity assist: you performed a maneuver wherein you save fuel by taking advantage of a celestial body's gravity and/or motion. Which is the wikipedia definition, and consistent with what turns up if I google across NASA pages. Maybe a studied aerospace engineer has it defined a bit more strictly, I wouldn't know...

Did I say I was going to paint a picture? Yes, that means exactly what you think it means. Behold!

Being in orbit is in essence just one big, neverending gravity assist. Specifically, you gain exactly as much acceleration from the slingshot maneuver as it costs to counteract the downwards acceleration from gravity. That is why your vehicle is always weightless in orbit, no matter how much gravity the orbited object might have and how close you are. By performing a direct ascent towards a destination, you do not get any gravity assist. You must pay extra fuel for what you usually get for free, namely counteracting the acceleration towards the local center of gravity. Therefore, burning for escape velocity out of an orbit is cheaper than a direct ascent, even if you were starting from the same height. This makes me want to paint a picture. BRB. in addition, the Oberth effect comes into play because you are moving faster during a horizontal takeoff than you would during a vertical one. After all, if you have a finite amount of acceleration from your engines, then the less you must subtract to account for gravity, the more is left to actually put you into motion. Therefore, after 5 seconds of accelerating horizontally, you are moving faster than after 5 seconds of accelerating vertically. This is especially true directly at liftoff, when your vehicle is chock full of fuel and you are deepest in the gravity well. The horizontal takeoff thus builds a strong early lead and benefits sooner and in larger amounts from the Oberth effect while simultaneously increasing it, which is quickly snowballing into more and more free acceleration. As it turns out, the combined effect of the gravity slingshot and the Oberth effect is so large that it is still cheaper to build a fully circularized orbit and take a roundtrip around the entirety of the celestial body rather than burning directly upwards. I personally thought the effect was not as strong, and there would be a point where the effort of building the orbit would be more costly. But maccollo handily proved me wrong. EDIT: Wow, massively ninja'd.

This is true for now, but it might be worth a reconsideration when .24 rolls around. Career mode launches will require funding, and funding will likely be tight unless you actively invest effort (through optional missions) to earn yourself a bonus. At this point it is pure speculation still, but we might be seeing a future in which regularly launching heavy lifters just to refuel orbital depots might not be feasible from a cost/benefit standpoint... at least, not unless you invest effort into paying for it. Then suddenly, the prospect of a "launch once" fuel-processing operation based on kethane could start making a lot of sense.

1. Take crew report 2. EVA Kerbal 3. Take all data from crew capsule 4. Put all data back into crew capsule 5. Board capsule with Kerbal Your crew report is now no longer stored as a crew report, but rather as experiment data instead (much like EVA reports are). Therefore you can now take another crew report without overwriting the old one. Which can be transformed into stored data in exactly the same manner.

I got it for free. ...No really, it was a christmas gift I do not know how much the gift-giver paid then.

The 48-7S only works so well on Eve because a.) it's broken beyond belief and b.) KSP neglects to actually continue scaling Isp beyond 1 atmosphere worth of pressure. If it wasn't clamped to that, we would likely see sub-100 Isp on the 48-7S on Eve's surface, while the aerospike would still be around 380. Honestly this should be implemented, because the aerospike could really use that niche. I'm probably going to use a mod to make it happen if I ever get around to visit Eve...

Very nice challenge, I see now the error of my ways. Had great fun using one of the linear RCS ports to keep the craft from dropping back to surface while burning in a completely flat trajectory Managed to get my Kerbin periapsis to disappear into the planet on the first try with fuel left that way, while with direct ascent I couldn't get it into the atmosphere.

Right. I have no seen people claim on these forums that: - Reaction wheels are best as far away from the center of mass as possible - Reaction wheels are best exactly on the center of mass - Reaction wheels don't care where they are in relation to center of mass Clearly there is a very large uncertainty in the community as to this topic, and most people are just guessing blindly or repeating what they have seen somewhere else. We need a proper test for this.

Excellent! Now I can confirm for myself if I was wrong. (...once I get home...)

Good to hear. The question is now... how much got broken and how much is left that can still be useful.

Well, it's a workable approximation. Looks like I wasn't too far off in eyeballing the average of the 350-400 engine at 390 I'm going to mark this as answered for now, since we're probably not going to get much more detail than this.

Interesting. How did you come to these numbers, UmbralRaptor? Is that based on simple examination of time spent reaching various heights, or is there math involved?

That's not a bad idea in theory, since it's actually possible IRL to "orbit" Lagrange points because the interaction from both gravity wells with its own movement can temporarily lock a spacecraft into repeating movement patterns near the point, which is far more stable than trying to sit still in the nullzone itself. This is called a halo orbit. Technically they exist only in the mathematical three-body problem and the real world needs to make do with the far less stable Lissajous orbit that won't hold for long around L1, L2 and L3 without stationkeeping, but L4 and L5 are much more stable. As a simplification, KSP could use tiny SoI's about a kilometer across or so where the player can put a ship into a tiny, near-stationary orbit around a center of very weak gravity but no actual celestial body there. This issue is that five Lagrange points exist for any three-body problem (i.e. any two celestials orbiting a common barycenter plus your spaceship), and as such, KSP would need a very, very large number of such points. And then there's higher n-body systems - for starters, Kerbin itself is one, with its two moons. Maybe the Lagrange points for the Kerbin-Mun system and the Kerbin-Minmus system respectively end up positioned such that Minmus could move its SoI over Kerbin-Mun L2, or the Mun could move its SoI over Kerbin-Minmus L1 or L3? In such a system, these points would be practically nonexistant because the close periodic passing of a gravity well would completely obliterate it. That's where having small static SoI's breaks down in a hurry.

Yesterday I built my most complex rocket yet. 147.5 tons in 176 parts and 12 stages, it carries three identical landers inside its payload fairing*. Each lander is a completely self-sufficient manned vehicle, fitted with 10 days fo life support** and enough delta-V to b able to land on either Mun or Minmus and return all five of its scientific experiments plus crew safe to Kerbin. The number three was chosen because Minmus has 9 and the Mun has 15 biomes to visit; both numbers divisible by 3. Therefore this rocket is perfectly suited for doing science on them. By inserting into a polar orbit and decoupling landers one by one when passing over the desired biomes, all possible ground-based science can be achieved in just 3 or 5 launches, respectively. * KW Rocketry ** TAC Life Support

Eve has a much thicker atmosphere than Kerbin so you need to haul it up further than 10km. For me it was honestly more a question of "I have this SSTO rocket and I want to calculate its delta-V by hand". For this I need an Isp value that averages the entire climb from 0 to 70km. But the question can be generalized for any rocket stage across an arbitrary height band.

I doubt that circularizing an orbit at more than 600 m/s before you even start burning for escape would be cheaper than a direct ascent in this case... of course, I am open to be proven wrong How would one go about to test this with little effort? Is there a way to cheat a lander to the correct spot on the Mun (or at least nearby in space)?

KSP doesn't have Lagrange points because it uses the patched conics model for simulating gravity interactions. Only one celestial body can affect your ship with gravity at any one time. That means you're trying to balance on an infinitessimally narrow knife's edge - no matter what you do, you will fall down one side. At best, you could get a trajectory where you drop out of the Mun's SoI and then get recaptured shortly after, but this definitely won't be stable for any length of time. What you could do is try to assume an orbit perfectly identical to that of the Mun, and position yourself a few hundred meters ahead or behind the edge of the Mun's SoI. This would be functionally identical to a Lagrange point in the sense that the craft will maintain a fixed distance to both the Mun and to Kerbin forever, but it wouldn't be in between the Mun and Kerbin.

The article seems rather politically biased. SpaceX probably could develop such a rocket if they really wanted, but I highly doubt it's quite as easy as Elon Musk makes it sound. He has long been known to make enormous claims under the protective cover of "future plans" - and while his ventures have indeed produced impressive results, it's always the more realistic, down-to-earth plans that get implemented in the end. He's a very smart man, he knows not to throw money at fruitless ventures. I'm fairly sure that when Elon Musk says "we could build this rocket for 2.5 billion", what he really means is: "I've tasked an engineer with giving me a rough estimate on a super rocket because I thought the idea was cool. And he said somewhere between 2.5 and 5.0 billion. Probably. We haven't actually drawn up any plans yet, though." In the meantime, I wish SpaceX all the best luck with next week's launch, and with the Falcon Heavy project later this year.

You could download , intercept the debris and blow it to smithereens?

I see... that's unfortunate. I suppose I will just have to keep estimating. The issue with using the sea level Isp is that that may work fine for stages that only burn for 10-20 seconds; but if you have a stage that goes all the way (or almost all the way) to orbit, you would vastly overestimate the amount of fuel needed. That's an interesting equation - unfortunately not what I was after, though. I'm looking for the average Isp across the entire flighttime of a stage. The formula given shows only a snapshot of a given moment. It basically gives me the same I can see ingame by right-clicking on the engine. I suppose if I integrated this equation I would get a better result... but for that I would need the duration of atmospheric flight as well as make the assumption that the climb rate is uniform over the entire integral. Can MechJeb do something like that - hold a craft at (for example) exactly 100 m/s for a fully vertical 20km climb?

I've been wondering how I should be rating my liftoff stages in terms of dV. Obviously the Isp sits at its ASL value when the rocket is on the launchpad, but this changes very very quickly. Most engines get within 1 point of vacuum value at 10,000 meters, and all engines hit vacuum value at 20,000 meters. So for practical purposes, 80-85% of the climb is done at vacuum Isp as far as height traversed goes. But rocket velocity isn't uniform, and to top it off, there's also the gravity turn constantly changing the climb rate. Has there ever been a discussion on this topic, about how to estimate the average Isp of a rocket engine across the entire climb from launchpad to X meters, while traveling at terminal velocity and executing a normal (leveling off between 70-80km) gravity turn?