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Everything posted by mhoram
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Ways to add more Delta V?
mhoram replied to Andrew Ridgely's topic in KSP1 Gameplay Questions and Tutorials
And here are examples of ships with a lot of Delta-V: http://forum.kerbalspaceprogram.com/index.php?/topic/54529-022-0230-delta-v-maximization-challenge/ They might give you ideas of how to extend your design. -
Deorbit too fast, airdrag not working?
mhoram replied to Taki1980's topic in KSP1 Gameplay Questions and Tutorials
This seems to be the problem. I don't use Deadly Reentry or FAR, but I have the feeling that you are way to slow. Usually I decelerate so that my Periapsis is around 30km altitude above ground when entering the atmosphere, which gives good results for me (probably differs for FAR and Deadly Reentry). I suggest that you try out different entry velocities. The reason is that the slower you are, the faster you hit the ground (Yes, this seems to be counterintuitive). That way you don't stay long enough in atmosphere to slow down. -
Have a look at your Navball. You can see on the edge between the blue and the orange hemisphere numbers (0, 45, 90, 135, ...). They indicate the direction you are facing with your rocket. If you want to make your orbit after take-off as equatorial as possible, then point your rocket in the "90" direction. The reason is that the numbers represent the compass points (North = 0/360, East = 90, South = 180, West = 270). (Note: launching in the West direction also makes your orbit equatorial, but I would not recommend this since you have to counter the planetary rotation, which means that you need more fuel to get into orbit) As you have noticed, the latitude of your landing site has also an impact on the orbit after launch. The farer you land away from the equator, the less your orbit gets equatorial after launch. If the orbit before landing is equatorial, then your landing site will also be near the equator, so this should help to get you into an equatorial orbit after launch.
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Regarding your first question head over to http://alexmoon.github.io/ksp/. This Webapp helps you with planning the needed Delta-V. Regarding your second question there are two options: 1. reduce the mass of your payload 2. increase your fuel/engines or add additional stages Here is a thread containing inspirations for creating Rockets with large amounts of Delta-V: http://forum.kerbalspaceprogram.com/index.php?/topic/54529-022-0230-delta-v-maximization-challenge/ Also you can get advice on which engine to use in which situation in the following thread: http://forum.kerbalspaceprogram.com/index.php?/topic/114995-web-111-optimal-engine-charts-interactive-webapp/
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I made some tests with the different parachutes in the following setting: - Mass of the vessel: 6.64 ton - The number of parachutes is chosen so that 0.6 ton of mass is reached for each parachute type - Deployment of the parachutes at a higher altitude so that at 500m altitude an equilibrium for the velocity is reached And the results are: Parachute # of Parachutes Velocity at 500m altitude Mk16-XL 2 (300kg) 8.4 m/s Mk2-R 6 (100kg) 4.0 m/s Mk25 3 (200kg) 50.2 m/s Mk12-R 8 (75kg) 27.0 m/s Mk16 6 (100kg) 6.5 m/s It looks like the radially mounted parachutes perform much better (masswise) than the others. Imgur Album
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Escape Velocites and Orbital Heights
mhoram replied to shadragon's topic in KSP1 Gameplay Questions and Tutorials
Cool, I was not aware that the escape velocity could be used for this. My approach for the escape-burn-DV calculation was to apply the Vis-Viva formula twice without using the escape velocity. (first to calculate the semi-major axis of the hyperbolic Kerbin-escape orbit and second to calculate the velocity at the periapsis) -
Escape Velocites and Orbital Heights
mhoram replied to shadragon's topic in KSP1 Gameplay Questions and Tutorials
A few comments on your post: Now that I think about it, Escape velocities do not provide essential information for mission planning: The most commonly used method for going interplanetary to a different planet is to burn in low Kerbin orbit in order to get an intercept with another planet (There are a few alternatives but lets keep this for this argumentation simple). In order to calculate this ejection burn, your table does not provide substantial information besides that the ejecteion burn is larger than "escape velocity - orbital velocity". Your table offers information about the Delta-V needed in order to leave Kerbins SOI (from a circular orbit at altitude 0). Such a maneuver brings you into a Solar orbit very near to Kerbins orbit. This target destination is only useful in very few occasions, so please don't be disappointed, if your table receives less feedback than you expected. Kudos for diving into the calculations! Also you might want to switch to a different file hoster: See here If you were to compile such a table, then I would recommend to look at the values you find in the Community Delta-V Map. These should provide you with information about important aspects of mission planning. -
Infos about Parachutes can be found at the Parachute wiki page. The best mass/braking force ratio can be attributed to the MK-16, MK16-XL and MK2-R. (EDIT: I stand corrected by RIC) The other two so called "Drogue" parachutes have a worse ratio while fully deployed, but they can be used at much higher velocities (400-500 m/s) to slow down your craft. Don't know, but maybe A.I.R.B.R.A.K.E.S is something, you would take into consideration.
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How to land rover on another planet?
mhoram replied to ARS's topic in KSP1 Gameplay Questions and Tutorials
Every part in KSP has an impact tolerance, which is mentioned in the VAB if you look at the details of that part. If you land your craft while your speed is above that tolerance, then the part will break. Wheels are a bit special, since they have an additional mechanic that causes them to break, but I have not learned yet, how this mechanic works. It does not matter, if you are "slowing my descent on full thrust", the important aspect is the velocity at the time of touchdown. Usually I try to land with a velocity of at most 5m/s during touchdown. What is your touchdown-velocity? If you touchdown at a much higher velocity, then it can be expected that some parts break. If so, then you should try to adjust your Mun-descent in a way that allows you to slow down more before touchdown. Here are a few links explaining different landing methods: http://forum.kerbalspaceprogram.com/index.php?/topic/94318-reverse-gravity-turn-landing-technique-for-airless-bodies/ http://forum.kerbalspaceprogram.com/index.php?/topic/36648-landing-and-takeoff-delta-v-vs-twr-and-specific-impulse/ http://forum.kerbalspaceprogram.com/index.php?/topic/134273-suicide-burns-on-the-fly/ Another consideration is the placement of the engines. Here is a thread with inspirations on building skycranes: http://forum.kerbalspaceprogram.com/index.php?/topic/55180-bsc-challenge-rover-skycrane-yet-another-winner/ -
Escape Velocites and Orbital Heights
mhoram replied to shadragon's topic in KSP1 Gameplay Questions and Tutorials
For mission planning Delta-V charts can help a lot: There are many Delta-V Maps available. They help you to estimate the Delta-V you need to get from Kerbin to the other planetary bodies (and back). For planning missions between other bodies, these two webapplications can help: - http://alexmoon.github.io/ksp/ - http://ksp.olex.biz/ Also there is a mod for this. I have never seen a chart of escape velocities, but it is quite easy to compile one by yourself by using the formula found on Wikipedia and inserting the mass of the planet. -
A psuedo Candarm/drone for stock?
mhoram replied to Jestersage's topic in KSP1 Gameplay Questions and Tutorials
It is a bit difficult to give a suggestion for TWR, because it depends on several factors like the mass of the drone and the mass of the object you want to transport. The larger the mass of the object you want to transport, the lower the resulting TWR will get. Regarding fuel you should have enough for performing your operations and you can refuel the drone after an operation, so keep a supply of fuel on your main station. Also keep in mind that grabbling another object means that you add mass to your ship which reduces the Delta-V you can expend. Another consideration you should take into account is torque. If your drone has too little torque, it will get tedious for you to transport and aim other objects. (In some cases I attached more than one Tuggy's (see below) to the object I was transporting in order to get a better handling) Lamps (together with batteries and solar panels) are (at least for me) essential: sooner or later it can happen that during the docking maneuver you move into the planets shadow where docking without light is quite problematic. Personally I find that the claw is unpleasant to handle, since it is difficult to attach it near the center of mass of the intended target, which makes precision maneuvering quite problematic, so I keep mostly to docking ports. Also there are two approaches for the craft, which have different implications: puller or pusher designs. - Puller designs with the claw are more stable than pusher designs, but can make docking the transported object difficult. - Pusher designs are easier do create, since you don't need to take care that the exhaust of the engines reaches the object you transport. All in all I would recommend, that you try out a design and change the details that don't work out for you. The solution I use for my space stations is the transport tug "Tuggy", a small RCS-fueled craft with large docking ports. It took about 5 design iterations of more or less viable crafts until I came to this design that fulfills most of my needs. And the cool part is, that it is stackable, because it has on both ends large docking ports. -
How much dV do you lose with a higher LKO really?
mhoram replied to dire's topic in KSP1 Gameplay Questions and Tutorials
After reading his latest posts, I came to the same conclusion. Everything about the Oberth effect has already been said in more detail and from more perspectives than I have ever seen in a single thread on this forum, and still it seems to be futile to try to convince him. Will bookmark this thread for future reference. -
How much dV do you lose with a higher LKO really?
mhoram replied to dire's topic in KSP1 Gameplay Questions and Tutorials
If I am missing something, then please tell me what it is and provide the terms missing in my equations. Calling the Oberth Effect an Isp buff is not how I understand the Wikipedia page: "The gain in efficiency is explained by the Oberth effect, which is that the use of a rocket at high speed generates greater mechanical energy." And no: A ship, that has 100m/s vacuum Detla-V left, has exactly 100m/s left, no matter if it is moving at 10m/s or at 1000m/s in vacuum. Try the following: Bring a ship into a highly elliptical orbit - according to your agumentation the remaining-Delta-V (MJ/KER) readout of the ship should change depending on the velocity of the ship - that is something, I have never witnessed. Please consider the possibility that it is you, who does not yet understand the Oberth effect. RIC explained it way better than I was able to: The Oberth effect is an observation of a fact and not an effect by itself. This observation is, that a vessel with a higher base velocity gains more kinetic energy from the same amount of Delta-V than a vessel with a lower base velocity. And the formula and numerical examples I gave, show exactly this fact. -
For the moment you could use the mod RCS Build Aid, which provides this functionality.
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How much dV do you lose with a higher LKO really?
mhoram replied to dire's topic in KSP1 Gameplay Questions and Tutorials
I disagree with this statement. The Oberth effect comes simply from accelerating at different velocities. Take these two cases for a ship with a total mass of 1000kg before the acceleration phase, 900kg after the acceleration phase and a total (instant) acceleration of 100m/s: 1. A ship travels at 1000 m/s before the burn The kinetic energy before the burn is: E = 1/2 m*v^2 = 1/2 * 1000 kg * (1000 m/s)^2 = 500 MJ (MJ in the sense of Megajoule and not Mechjeb) The kinetic energy after the burn is: E = 1/2 m*v^2 = 1/2 * 900 kg * (1100 m/s)^2 = 544.5 MJ It gained 44.5 MJ energy from the 100 m/s acceleration 2. A ship travels at 10 m/s before the burn The kinetic energy before the burn is: E = 1/2 m*v^2 = 1/2 * 1000 kg * (10 m/s)^2 = 50 kJ The kinetic energy after the burn is: E = 1/2 m*v^2 = 1/2 * 900 kg * (110 m/s)^2 = 5.445 MJ It gained 5.395 MJ energy from the 100 m/s acceleration. So in the first case the energy gain is much higher than in the second case. There is no need to apply any Oberth-Function. -
[1.12.x] Trackingstation Ambientlight [v0.3.4, 2021-08-25]
mhoram replied to mhoram's topic in KSP1 Mod Releases
Thank you for letting me know. I corrected this and uploaded a new version to spacedock. -
First ever shared craft! pictures added!!!
mhoram replied to nascarlaser1's topic in KSP1 The Spacecraft Exchange
By not asking: "How do I increase my ships popularity?" ;-) But seriously I can think of some other answers for this question: - Create other ships that are impressive in some way - Be creative - You received already some advice from other forum members in the other thread. Incooperate that advice into the next version of your ship and publish that one: Designing a good ship is an iterative process fueled by learning from mistakes in earlier versions and the wish to improve ones creations. -
The biggest thing I've ever launched...
mhoram replied to GoSlash27's topic in KSP1 The Spacecraft Exchange
It was for the Challenge that I linked. The intention was to create a station with the highest energy output. -
The biggest thing I've ever launched...
mhoram replied to GoSlash27's topic in KSP1 The Spacecraft Exchange
Sizewise it was the "Giant Gigantor" with 262 solar panels in the old days before the aerodynamics change. The ship was a bit taller than the VAB (full album) -
[1.12.x] Trackingstation Ambientlight [v0.3.4, 2021-08-25]
mhoram replied to mhoram's topic in KSP1 Mod Releases
You are welcome. When I recently installed KSP again, I missed this feature. Sorry, but I am unable to reproduce what you are describing in stock KSP. Perhaps you already have one of the other mentioned similar mods installed? -
You can find the map you are looking for here. It is based on the assumption that you first leave Kerbins SOI before starting the Hohmann Transfer to the other planets.
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[1.12.x] Trackingstation Ambientlight [v0.3.4, 2021-08-25]
mhoram replied to mhoram's topic in KSP1 Mod Releases
Published new version for KSP 1.1.3 -
How do you add signatures
mhoram replied to Wildcat111's topic in KSP1 Gameplay Questions and Tutorials
Click on your name in the upper right of the website and "Account Settings". There you can find the signature editing form. -
For elliptical orbits, you can find a formula here: http://wiki.kerbalspaceprogram.com/wiki/Orbit_darkness_time
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- battery life requirements
- dark side transit
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Well ... you can use explosive decoupling with all available staging methods ;-)