MaxL_1023

Is it possible to change the time warp constraints for Phobos and Deimos? The low orbital speeds make it take forever to orbit them at the distances required for near-space science and landing maneuvers.

So you're telling me that those three clown astronauts have already been to the Mun and back and have the temerity to make me start off the KSP with trashcans?!

Why do people hate ISRUs? It actually makes it harder to do most single body return missions (except for Duna/Eve/Laythe/Tylo) since the weight/cost of the ISRU + Drill + Extra electric generation makes it require a much larger rocket to actually get you off Kerbin, often in the 1000+ ton range. A Lander can + 5 FTL-800 + 5 Terriers (asparagus or radially staged) will get you basically anywhere and back (except Tylo and maybe Laythe) with a Mainsail + Kickbacks then Skipper lifting it into orbit - you often don't need 3.75m parts at all.

Your payload fraction there is about 5% if you include the solar panels and potential science gear. I would personally just stick the small ISRU and a mining drill on a lander - it cuts your delta-v requirement in half and lets you hop from moon to moon.

I am using 1:beta-06-3 from the CKAN library with KSP 1.05. My craft float fine on Kerbin, so I don't think this is the issue. I had a heatshield still attached to the top of the probe - when I hit Laythe's ocean I "bounced" off the surface with the splashdown sound repeating. When I decoupled it, I sunk as if I was in free fall. This occurred with a full ore tank attached, an empty ore tank attached and a naked octo core (octo I, not octo II).

Yes, I am using Cryoengines. Thank you.

Hello, I am using the New Horizons mod, and sent a mission to Laythe's oceans. Laythe appears to be the same body in stock, just moved to its own orbit and with a moon added. Either way, my probe with one full small ore tank, an Octo core and some science instruments sank at over 100m/s, which I did not think was possible in water for something with realistic density. Even with the ore tank empty, it sunk at similar speeds. What is the density of Laythe's oceans? Are they modeled as water or air? If their density is something like 0.2g/cm^3 than I could understand the dynamics (liquid hydrocarbons?) but if it is supposed to be water then something is off. Maybe the New Horizons mod changes it around? Thanks, Max

I might have found a bug with the "Penguin" Vacuum engine. It seems to use BOTH thrust configurations at once as default, meaning you get 1200KN of thrust instead of the expected 600. I could deactivate either or both engines at the same time, leading to getting back the original 600KN at 400 ISP (which my design used). It is supposed to work that way, or is something glitched on my end?

Those are called "patched conics." Basically, the blue orbit is your current orbit, orange is your orbit after one SOI change, purple is your orbit after two SOI changes. When your orbit encounters a planet/moon (Mun, Mimus, the Sun, etc.) by passing close enough (or far enough from Kerbin) the game will change which body is applying gravity to your ship. Assume your orbit has you pass within about 1000km of Minmus. You are then close enough for Minmus' gravity to dominate your path. KSP tells your ship to feel gravity from Minmus as opposed to Kerbin (you only get gravity from one source at a time). Your velocity and position causes a new orbit (usually a flyby, or an open orbit) which is labelled in orange, as you are not on that orbit yet, but will be soon. When the orange orbit leaves Minmus gravity field, you go back to a Kerbin orbit labelled in purple, as it is two orbits away. Notice that it is different from your blue orbit, as Minmus' gravity changed your velocity. The closer you get to Minmus, the greater the change would be. The orange path will only appear if you are going to have an encounter on your current orbit. Watch out if your orbit passes close to the orbits of the Mun or Minmus, as you may eventually encounter them on future orbits. If you don't want this to happen, you need to make sure your orbit passes nowhere near their paths. You might lose your ship - it is quite possible to encounter the Mun in such a way as to hit it. Minmus is less likely, but also possible. An encounter with either of them could also throw your craft hard enough to escape Kerbin entirely, and end up orbiting the sun.

A rough rule of thumb: 1. Straight up until you reach 100m/s 2. Turn ~15 degrees eastwards 3. Keep your nose pointed prograde (in the direction of rocket motion) 4. If you are below 45 degrees at 350m/s, turn up, If you are above ~60 degrees, turn down. Anything else shouldn't cause too much trouble. 5. If you get below 15 degrees before 30km, pitch up a bit until you get to 40km. 5. Once you pass ~40km, turn horizontal until your AP gets to where you want it. Basically, you don't want to need too much fuel to circularize (the 60 degree rule) but also don't want to have to plow through air below 40km when your velocity approaches orbital (rule 5). The 15 degree turn and prograde alignment is a gravity turn - it basically makes your rocket turn itself into orbit.

FAR (Ferram Aerospace Research) will tell you your L/D ratio in real time, but as it also changes aerodynamics around your values would probably be (at least slightly) different in stock.

The problem is gravity losses. With a starting TWR near 1.0, you pick up a considerable amount of vertical velocity in the time it takes to cancel your orbital speed. Then, you need to cancel this vertical speed by the moment of impact. This forces additional gravity losses proportional to 1-TWR. If your TWR is high enough to make an efficient landing (think 5-6g suicide burn at least) then you will tend to have a lot of lander weight tied up in engines. You want to do a reverse gravity turn type situation, where you have a PE near the surface and you burn progressively more normal as you cancel orbital velocity, just enough to keep you from hitting the ground. The higher your starting TWR, the sharper this turn is and the closer you get to the ideal "instant suicide burn at a PE of 1m cancelling all orbital velocity." It might be possible to do this with a single stage and return to orbit, but I suspect your payload fraction would be close to zero.

You can also get this when turning - if you try and pitch too quickly you can briefly get negative acceleration at the engine and get vapor problems. If your engine shuts down with 3/4 fuel and no vapor message, you are probably using an incorrect propellant mix. For example, your engine might want 65/35 of something while you have it reversed, meaning you run out of one propellant type quickly and leave a large amount of the second remaining. Double check that your engine requirements are met by your fuel tanks, and no non-crossfeed parts are blocking fuel flow (the A4 guidance unit is bad for this).

Ok, thanks for clearing that up. I must have had a PE a bit higher than I remember.

I am not sure honestly, but something is odd with the way craft on rails behave. They seem to survive atmospheric passes (20km PE ) unaffected when hyperbolic but AFAIK they would be killed when put into (for example) a 100kmx20km Kerbin orbit.

I think it might stem from the rails system - a craft on an escape trajectory will usually survive an upper-atmospheric passage afaik (when not loaded by physics) while something in a closed orbit would be be auto-destroyed simulating re-entry. I have had situations where I lost a craft on a hyperbolic re-entry (underestimated the heat loads compared to orbital speed) but some pieces with command pods (those mechjeb modules are nearly indestructible) were still intact when I went to space center. Even though the pieces should logically have either landed,crashed or burnt up (nothing makes it back into orbit from a 20km Kerbin PE) they ended up staying on their escape trajectory with no atmospheric effects applied when out of physics load range.

Your plane will explode long before you get to 6000 m/s anywhere within 60km of Kerbin. If you want to do it with rockets, just stick an Octo core on top of a Rockomax XT-32 and put a poodle on the back. You will get to 6000m/s assuming you stick a booster on the bottom to get it above most of the atmosphere.

Atmospheric flight is any travel within a planetary atmosphere except for escape trajectories. Basically, you must have a closed orbit at some point within the atmosphere. If you were not captured by Eve and just flew past into a solar orbit you will not receive credit for the mission. Thankfully, it only takes a couple hundred m/s of delta-v to get from a very high elliptical orbit back to Kerbin, so try burning a bit at perapsis to close an orbit. If you have a heatshield, you could lower your Perapsis to 75km or so and probably aerobrake into orbit. Your AP can be anywhere, as long as it is within the SOI of the planet (non-hyperbolic). I usually get the achievement when aerobraking or re-entering Serran or Laythe (using the New Horizons mod).

Squad: "KSP has undergone a rapid unplanned disassembly."

The Vector is hilarious when using tweakscale - the 1.25m base size makes a 3.75m vector several times more powerful than a Mammoth. Besides that, nothing is really wrong with it performance wise besides the weirdness resulting from sticking one on a 1.25m stack and getting insane TWR. I think it should be a 2.5m part with the same model (add a plate attachment or something) but that is not a major issue.

I strongly recommend using the contract configurator mod - it lets you remove the "test part" contracts from the generation algorithm. They are automatically replaced with contracts from some other area. You can then select which contract types you like to see. I usually delete tourism, satellite, rescue (once I have enough kerbals) and testpart contracts by clicking one button each, and go to town on exploration, plant flag and science from body contracts. You will get situations where you can explore a body, leave a probe on it and collect money periodically as a science from X pops up. No more "test a mammoth on a suborbital trajectory over eeloo" contracts = fun all around.

There are a couple shortcuts that could be used to make something like this work: 1. Assume sun-tracking panels have a sun exposure of 90% or 100% (or some other number, removes orientation checks in deep space) 2. Assume static panels have a sun exposure of 50% (same as above, removes a wrap exploit). 3. Assume power is routed to the ion drive last, after all other rail-monitored sinks 4. Ion thrust is applied through the CoM regardless of actual engine location (no real exploits, since you can get the same effect by orienting the craft in 1x) 5. Assume the craft velocity vector and orientation is constant within a timestep. This way, the ion engine will serve to thrust the craft along the instantaneous rail direction. If you split this into timesteps you can get the following operation: 1. Using initial conditions (power generation plus location/velocity) you calculate the instant available power to the ion drive. Throttle it automatically to obtain the thrust vector. Calculate fuel consumption. If the craft has insufficient fuel, throttle down the engine further until consumption = remaining, with the excess charge being discarded. 2. Calculate the ion-resultant displacement change as: 0.5 * (thrust vector)/mass * timestep length ^2. Also calculate the final velocity vector. 3. Superimpose this change on the current rail by moving the point at t + timestep accordingly. 4. Starting from t + timestep, calculate a new rail using the updated position and velocity. 5. Repeat The timesteps could be about 1 second long, with the rails in this mode replaced by small linear segments. A warp of 10x or 100x should be doable using this model. The original rail could be linearized using the trapezoidal rule with the original expected t + timestep location, with the thrust vector used to basically slightly lengthen the segment. The rail calculation update would only require a few timesteps worth of rail (at most) to be calculated, with the normal full rail being reestablished when the mode is exited, or every set number of timesteps. This should allow a craft to thrust under ion power, with the low thrust/changes relative to the timestep length minimizing linearization errors. If enough computing power is available, a simplified physics model could be used instead (only one force due to the engine and one vector for gravity, all others (intracraft) deleted) to get a more accurate model.

That works (although it looks a bit strange) however it can give you trouble on ascent if you are not careful, especially if you are early game without some AV-R8 fins or swivels on your first stage. Also, if your payload is too far back or even slightly larger than your pod you will get re-entry heating on it. You also can't do a lifting entry with that (lifting re-entries are often used in RSS/RO to reduce g-loads, not so much in stock though) since even a slight offset from retrograde will put full heat on those extra components. Honestly, I would recommend just doing an EVA and taking the data out, then throwing away the science pods before re-entry. A pod-alone entry is easier to control and is more forgiving, especially if you have a heatshield on it.

You need a heatshield to survive a re-entry in 1.05 unless you have a single pod with nothing heavy attached anywhere. The Mk. 1 by itself can survive (but it is close) if you use a good trajectory, but a materials bay will be destroyed. An engine can survive, but you need to jettison it before you hit 10km to slow enough to deploy chutes in most cases. If you have good control authority (reaction wheels, just a pod or RCS) try a lifting re-entry. It makes your re-entry angle get shallower as you hit thicker air and gives you more time to slow down. Basically, pitch your pod up 20 or 30 degrees (assuming nothing overheats like a chute or goo container) and you should slow down more easily. Once the air gets thick enough to force you retrograde you should be slow enough to make it to chute speed at 5-7km.

No ablator is perfect. Besides heat flux to the rest of the craft, you need to consider the mechanical durability of the shield itself. At those temperatures, extreme ablation will burn through in some areas and break the shield apart in others - the act of sublimation itself adds local forces to the heatshield body. The Apollo missions needed special heatshields rated for Lunar returns (10-11 km/s as opposed to 7.5 km/s), lifting re-entries (very hard to do manually in KSP but possible) to reduce the aerodynamic loads and still had a re-entry window which I heard described as hitting a bump on a basketball. Basically, you are asking too much of your heatshield. It already takes a badly-aimed ballistic re-entry from an interplanetary trajectory to burn one out on Kerbin - they are fine for Eve orbit entries or even aerocapture passes if you keep your angle of approach reasonable. You also might just have too much weight behind your shield - if your mass/drag ratio favors mass you will maintain speed further into the atmosphere and end up with higher heat loads. Try making your craft wider (2.5m shield on a 1.25m stack can work with an adapter) and you won't have as much trouble.