Aegolius13
-
Posts
1,059 -
Joined
-
Last visited
Content Type
Profiles
Forums
Developer Articles
KSP2 Release Notes
Bug Reports
Posts posted by Aegolius13
-
-
When the Kerbal returns to a pod, you should be able to right-click the pod and select "review stored data." Then you can transmit it, delete it, etc.
-
I'm a little confused about the mission profile - does it land on the Mun and just go back to Mun orbit to refuel? Or does it come back to Kerbin?
If you're only going down from Mun orbit and back, you don't need a lot of range so convenience may play a role as well as efficiency. For an ordinary-sized lander, the Terrier is usually a good all-round choice. As mentioned above, they're short so you don't need a ton of landing leg and can stay close to the ground. If one doesn't provide enough thrust, you can always cluster several. Sparks can serve a similar purpose the same thing for smaller landers, and again you can use more than one if you want a little more thrust. Poodles are good for larger craft or higher gravity, but are probably overkill on the Mun for anything short of mining ship.
If you have Making History, the Cub is a nice lander engine. Best thrust and ISP of any of the radials. Only catch is they only gimbal in one axis each, but reaction wheels usually suffice for attitude control.
Nuclear engines can be useful for big mining rigs and the like, but for a typical lander, I think it'd be more trouble than it's worth to accommodate their height.
-
17 hours ago, bewing said:
Generally, it's whether you have communication back to Kerbin or not, and whether you have a pilot onboard.
I've never really understood the purpose of this restriction. I get not being able to create a new node. But deleting an existing one doesn't really give you an advantage; it's just nice to reduce the clutter.
-
On 9/7/2019 at 10:07 AM, amateur astronaut said:
I'm planning building one with mk4 parts to hold 16 kerbals in it, but all I know is you need rapier engines that can get you to LKO, and then just nuclear engines to the rest of your flight... though should i calculate the delta-V with that little community map? or just test if the rapiers work, and then just off we go? I really would like to know if I would need to make any calculations with the nuclear engines...
First step is making sure your SSTO can make it to orbit at all. Once you've accomplished that, make sure you've disabled your Rapiers. If the nuclear engines are the only ones active, the delta-v readouts from either stock or KER should take into account the ISP of the nukes in calculating your available delta-v.
If you want the maximum range possible, it will likely mean a plane that just barely has enough thrust on nuclear propulsion to make orbit, so as @bewing says it can be a very fussy process. When I was building a single-stage-to-laythe and back, I did this kind of iterative test over and over and over. Make a tweak to plane (fuel, engines, aerodynamics, etc.). See if it can make it to orbit. If it can't, tweak again to address the problem. If it can, note available delta-v in orbit. Then make more tweaks for possible range improvements (more LF, less oxidizer, fewer engines, etc.), and lather, rinse, repeat.
Note, however, that if you want to land somewhere and return, you may need to use additional engines to get the necessary thrust. Rapiers in jet mode work great on Laythe; but anywhere else of course you'd have to rely on some form of rocket power. So that may add add a complication to getting a simple available delta-v number. I used some cheaty hyperedit testing to figure out approximately what my plane would consume landing on Laythe and getting back to orbit.
-
I don't think what you're looking for is possible without mods.
One option would be to use HyperEdit, which lets you land a craft at a specified latitutde/longitude. If you plunk down your launchpad at an exact coordinate, and then plunk down your rocket on top of that (setting a bit higher altitude for setdown), that might put the rocket in the right place. Or it might all blow up. Amusing either way in my book.
There's a mod for extraplanetary launchpads called... Extraplanetary Launchpads. I haven't used it so not familiar with it; dunno if it lets you add pads on Kerbin as well.
Sounds like KSP2 will have something closer to this feature with the colony system.
-
On 9/6/2019 at 12:52 AM, Space boy said:
when I try using swivels and relliants, the TWR becomes too high, as the people above said you want the TWR to be around 1.4 or something like that. So i dont understand this.
Having a high TWR at the start is not necessarily a bad thing in and of itself. For the first few seconds after liftoff, when you're going too slow for aerodynamics to matter and you're losing a large portion of your thrust to fighting gravity, you want all the TWR you can get. Things can get out of hand later in the launch, but if you start to accelerate way too fast, that can be solved by throttling down.
The reason people advise something in the 1.4ish range is more about efficiency. If you're familiar with the Rocket Equation, it tells you that rockets get delta-v (and hence range) but having a lot of fuel mass and very little mass of anything else, including engine mass. If you have a very high TWR, it means (1) you're missing out on the opportunity to add fuel, and extend that stage's range, without hurting your performance, and/or (2) you're using a bigger engine than necessary, and thus carrying more dry mass than you really need.
Thus it's generally not advisable to switch engines just to get a low TWR. If a less powerful engine fits the profile better, then by all means switch. But if the alternative engine is worse for the task at hand, no need to switch just to lower your TWR.
The Swivel and Reliant are interesting case studies . The Reliant has more thrust, less weight, and higher sea-level ISP. The Swivel's advantages are gimbal and better vacuum ISP. If you have another means of attitude control, like fins, I find the Reliant is better suited for boosters due to its sheer thrust, while the Swivel can make more sense for a core stage. But the ideal layout can vary from mission to mission.
Which is a really, really long way of saying that if you want to maximize range, using Reliants and adding fuel until TWR falls into the sweet spot is probably the better call. But if your rocket has enough range with Swivels, that's perfectly fine too.
-
13 hours ago, Space boy said:
What should I do if I want to send two kerbals at the same time. All i have for a two seater pod is the pea pod, which unfortunately, leads to aerodynamic havoc.
Been said above, but putting everything from the Ants in a fairing should solve your aero worries. This will also let you lose the nosecone, and not have to worry about blowing up science instruments or anything.
I actually like the Soviet capsules for certain things. Since they come with a built-in decoupler and heatshield, it's a decent tradeoff for the needed reaction wheel. Plus, for some reason, the abator burns off incredibly slowly, so you can cut down the amount to save some more weight. And, OP mentioned, they're nice for cramming many Kerbals into a small volume. And I often use a fairing even with the conical capsules anyway, if I have a draggy spacecraft, low-temp-tolerance instruments, etc.
-
Not aware of a direct way to do this, but you can always use the cheat menu (alt-f12) to complete the contract.
-
2 hours ago, sevenperforce said:
Hmm. I'm still not sure what you're intimating.
There is no "mixing" with "hot preburner exhaust" because hot preburner exhaust is the only thing that enters the combustion chamber.
I mean that the "hot preburner exhaust" is itself a mixture of the CO2 / H20 formed by preburner combustion, and the remainder of the 90% of the methane/oxygen flowing through each respective pump. The "mixing" (probably a poor choice of words by me) occurs at the point of combustion in the preburner - I didn't mean a separate stream of propellant was being added later.
What I was trying to say was that in full-flow staged combustion, the propellant entering the combustion chamber would presumably be cooler than whichever propellant was being routed through the turbo in a single-turbo staged combustion engine, since in FFSC all of the propellant is available to absorb some of the preburner heat. (Hence the similar exhaust temperatures you cite). Whereas in an SSME for example, the fuel-rich gas entering the combustion chamber would be pretty hot, and the oxygen would be pretty cold.
But anyway, your numbers on exhaust temperature were what I was looking for.
-
2 hours ago, sevenperforce said:
There's no extra fuel/oxidizer; that's why it's a Full Flow Staged Combustion cycle. Something like 90% of the LOX and 10% of the CH4 runs into the oxidizer preburner; something like 10% of the LOX and 90% of the CH4 runs into the fuel preburner. Then 100% of both exhaust flows is routed into the combustion chamber, so you have a purely gas-gas reaction in the chamber, leading to very high efficiency. All of the propellant goes through either one preburner or the other.
I think we're saying the same thing, me not very artfully. "Extra" was supposed to mean the majority of the fuel / oxidizer that passes through but doesn't get burned in the respective preburner. Which, presumably, would mix with the hot preburner exhaust such that the mixture is not very hot by the time it reaches the combustion chamber.
-
13 hours ago, sh1pman said:
Raptor engine has 3 igniters, one for each preburner and one for the main combustion chamber. Every igniter is also double-redundant. I’m not sure about the order, but it makes sense to first ignite the preburners, and then the combustion chamber.
Thanks. Makes sense they'd have to also light the preburners. Guess this is one of the (probably many) reasons FFSC is tricky enough no one's flown one before.
Not that this is probably ever going to happen, but the Hopper success makes me wonder -- if, hypothetically, SpaceX decided to make an expendable version of SH and a simplified Raptor-based second stage, how much more time / money would that take? Seems like we more or less know Raptor works, assuming (1) that orange flame was not a major problem, (2) the interaction of multiple of Raptors won't pose new problems, N-1 style, and (3) they can air-start the upper stage. Making structures and tanks out of steel seems almost trivial based on what's happened to date. The big challenges remaining with the official program seem like propulsive landing and heat shielding, but those wouldn't apply to a hypothetical expendable system.
As far as cost, I think Everyday Astronaut estimated that Raptors cost $2 million each, with the price hopefully coming down due to mass manufacture. The steel stuff is very cheap per Elon. The fuel is very cheap. So even if you threw the whole thing away, a simplified version of the whole thing should cost, maybe, one or two hundred million dollars?
The nub of my question is, as you might expect, how much more would SpaceX have to do to have a working rocket that matches or beats SLS in performance at a far lower cost? (Putting aside political issues, of course).
Final thought - in the spirit of Bridenstein Kerballing Orion on top of Falcon Heavy, if you were able to put an RL10 or BE-3 powered third stage on top of this hypothetical rocket, that seems like an awful lot of delta-v for something like Europa Clipper.
-
The ignition issue with Starhopper on Monday got me wondering - how does ignition on a preburner vs. combustion chamber work? Do they separately ignite them both? In a certain order? I would have thought that in a closed-cycle engine, if the preburner was going, the hot exhaust might be able to light the main chamber without a separate ignition source. Though perhaps not in a FFSC design where the exhausts are getting mixed in with all the extra fuel/oxidizer, and presumably getting cooled substantially.
-
14 hours ago, VoidSquid said:
Actually it says the rocket has 50 parts, and the maximal allowed number would be 255, VAB expansion level 2.
Whoops. So it does. Was thinking that was some kind of stage/ total thing.
-
The engineer's report says your rocket has 255 parts. That seems like some kind of glitch. You might want to try removing parts and putting them back on until you see that number normalize. I've had quite a bit of trouble with the symmetry on those bi/tri-couplers, where it stacks multiple instances of the same part in each of the nodes. So I'd suspect that first and foremost.
Otherwise, I agree with everything @5thHorseman said, though I tend to like my initial TWR more in the 1.4 to 1.6 range. But since SRBs increase more than LF engines in TWR as they burn out, starting a bit lower with an SRB stage might be prudent.
Another thing to consider is using Swivels on the second stage. As mentioned, you have more than enough TWR, so the hit from the Swivels isn't much. And they would likely provide better overall specific impulse - their sea level ISP is lower, but by the time the SRBs burn out, they may have closed the gap, and will continue to do so as you climb. Plus, the engine gimbal should help with your roll issue (two or more gimbal engines can control roll).
If you downsize to 2-way symmetry and need to add back some rocket, it looks like you could add some more fuel to that second stage.
-
I like to stack multiple satellites per level, as shown below (those are smaller sats of course, but the same concept applies). You can do the same on upper levels using cubic octagonal struts to create extra nodes). But I find it makes sense to put fewer sats on the top, so the fairing can taper around them.
-
22 hours ago, MPDerksen said:
Great answers. Thanks.
Follow up clarification: When building a rocket, how do I evaluate it’s ISP and TWR? Specific example, I’m prepping for my first mission with a rover under a lander. I want to construct a lifter to get it into LKO. Some of my designs take off and I get heat build up, others seem to accelerate VERY slowly and I burn for a VERY long time before getting up to orbit.
It would just be nice to have some guidelines for basic construction. Getting there.
The mod Kerbal Engineer Redux is great for seeing stats these stats, both in the VAB and in flight. The newish stock Delta-V tools button is helpful too in the VAB, and lets you check ISP at any given altitude, but I tend to still use KER.
In flight, you can right click an engine and see its ISP at that particular moment.
When you take off, you can also get a rough idea of your TWR by looking at your g-meter. A rocket with a TWR of exactly 1 would hover, and show 1g. A rocket with 1.5 TWR would show 1.5g, and so on.
-
2 hours ago, tcdonald said:
For space maneuver: ISP>TWR
Engines: Terrier, Ant, Poodle, Rhino, Nerv. Their thrust increase in vacuum as well
I'd add the Spark to the list of good vacuum engines, though it can be good in both roles. While its ISP is not top-tier, it's great for smaller payloads. And in relatively TWR-intensive vac applications like lander, a cluster of Sparks might beat out a Terrier.
Making History engines: Cheetah and Wolfhound are vacuum engines. Kodiak, Bobcat, Mastodon are launch engines. The Skiff is a bit of a tweener; kind of a beefed-up Swivel. The Cub is usable in both roles if you want a radial engine.
-
I'm having a little trouble picturing this, especially what you mean by "falling" ; can you post a screenshot or video?
First order of business might be to verify you don't have any extraneous commands in your action groups, or staging sequence.
You could also try setting separate action groups for your subsequent events, rather than using the regular staging sequence.
-
1 hour ago, MPDerksen said:
I've asked this before, but cannot find the reply. Sorry for that.
Thus far I mostly build my rockets based on dV goals. But I also seem to burn much more to attain orbit than published (yes, my gravity turns are within margins). I don't know how to select the right engine/fuel for a particular goal. I don't know when to use SRBs vs. some asparagus-staged LF engines. Stuff like that. While this is mostly true for launching off Kerbin, I think the same issue is true for my landers that need to escape Mun, or Duna etc.
Without becoming a huge math lesson, could someone break this down for me?
Michael
So you're saying you're measuring delta-v as shown on your craft, before vs. after launching, against what the chart says? The ISP of your engines will not affect "efficiency" by that metric, because it's already baked into the delta-v numbers. High TWR will, however, generally lower the delta-v taken to get to orbit, by reducing gravity losses.
The (slightly oversimplified) way I like to think about it is: your delta-v supply is based on how you build the rocket, and your delta-v consumption is based on how you maneuver.
Does that mean TWR is better than ISP? Well, no (or at least not for that reason), because "delta-v to orbit" is not a terribly useful metric. You could build a rocket with atrociously low ISP (all SRBs and Puffs, let's say), which might have a typical delta-v to orbit figure, but it would probably still be a lousy rocket because you'd have to build it huge due to all the fuel you're burning.
Perhaps a more direct way to look at it is to figure out what you need to accomplish your intended mission (delta-v, parts, thrust, etc), figure out what the appropriate rocket would look like in orbit, and then build to suit. If you're on a career game, it might make sense to optimize by cost, which often means low-tech parts like SRBs and Reliants. If money is no object and you want to build a small, sleek rocket, you might end up with expensive parts like Vectors.There's no categorical best answer, since after all, it's an open-ended game.
All that said, as a very general rule, ISP is relatively less important in earlier stages of a rocket, and more important in later stages. You can get away with an inefficient, heavy booster at launch because you don't need to consume fuel moving it around the solar system. But in an upper stage, every bit of weight matters a lot. You also inherently need a higher TWR at launch than when you're near or in orbit, since you have to fight gravity losses and want to quickly get high and fast. So people often prioritize thrust in lower stages. This is all true in the real world as well, which is why we tend to see lower ISP, high thrust engines at launch (think shuttle SRBs or the Saturn V first stage), and more efficient engines on later stages (e.g., hydrogen-burning J-2 or RL10).
-
10 hours ago, Space Nerd said:
When doing a gravity turn, the faring base just 'snips' off.
How sharp is your turn? Are you doing a degree or two pitchover at the start, or shifting 90 degrees in one go?
What size decoupler are you using? If it's a tiny one, it might be getting overwhelmed.
How is the clearance between the payload and the fairing? If something collides into the fairing, bad stuff can happen, though I wouldn't expect the fairing base to fall off.
You might want to try autostruts. E.g., autostrut the fairing base to the heaviest part (which will probably be something in the booster), and autostrut something in the booster to the root part (which should be in the plane).
A screenshot would also help diagnose the issue.
-
Further further to the comms issue, I think on the hardest settings, there's a gap between groundstations during the standard ascent. This can be dealt with by building a set of relays around Kerbin. But if you never get signal at all, it's probably not this.
Alternate idea - you could make sure you're not running out of electricity for some strange reason. I believe dead probe cores show lack of signal. This seems quite unlikely with batteries and an engine alternator going, but could be a bug or something.
Just now, k00b said:i am guessing OP forgot to put an antenna on it OR not appropriate satelites in orbit.
otherwise running out of electricity because of all the probe cores... (are there solar arrays in shroud and are you deploying them when in orbit?)
(guessing because i have experienced both problems....)
The pods/cores come with a built-in lousy 5k antenna. It's not good for much, but it should have no problem picking up a signal right at KSC.
-
Hi, and welcome aboard!
Do you mean the Hitchhiker module? It should have usable hatches. If you aren't close enough to the target (2km I think), you're not even able to focus on the craft, but it sounds like you're past that point. You could try both clicking on the portrait, and left-clicking on a hatch, and see if one works for an EVA.
I can't think of any part on a Kerbal rescue contract that isn't supposed to let you EVA the Kerbal. Sometimes on missions where you have to recover the craft as well, you need to use the Klaw to grab the other ship. You shouldn't need that here, but I suppose you could try it as a workaround.
-
4 hours ago, Spaceten said:
Also, are you refunded for debris that safely lands on the ground - is there any point in sticking parachutes on boosters for instance? Since the debris just disappears without me having to recover it from the Tracking station or Space center it is hard to tell if you get any funds back.
You only get refunds for stuff you manually recover. And as noted, parts generally disappear when left unsupervised in atmosphere. So in stock / typical gameplay,* there's no reason other than roleplaying for putting parachutes on boosters.
However, you might be interested in the "Stage Recovery" mod. I haven't used it myself, but I believe it does exactly what you're referring to -- provides funds for decoupled but "survivable" stages.
*In some cases, you can do some fairly convoluted switching between craft to get stuff to survive, but it doesn't happen during a typical launch with focus on the main craft.
-
If your station has enough fuel, another way to do this would be:
1) Before separating, do a retrograde burn, just enough so that the entire craft is on a deorbit trajectory. Might as well use the thruster module's engine/fuel for this.
2) Rotate so that the station module is facing the prograde/forward direction.
3) Decouple the thruster module.
4) Use the station's propulsion to burn prograde and put it back into the desired orbit. I can't see if you have a full engine on the station, but even the RCS blocks shoud be able to do this in plenty of time.
something wrong with relays
in KSP1 Gameplay Questions and Tutorials
Posted
Side note - you COULD operate the lander as desired if you have one of the command pods with the "remote control" ability, and the requisite pilot count, in the "carrier" vessel. That lets you bypass the need to get the signal back to Kerbin.
https://wiki.kerbalspaceprogram.com/wiki/Probe_Control_Point