CFYL

whoa that's your new page. -39

-39 whatsoever

Jeb's friends. Built two other unkerballed ships, which has jets that can work underwater, one to crash into the rock hard and destroy it, another to save Jeb. This ship is categorized by KSP as an aeroplane and it is piloted by Jeb as a submarine.

-79. This is 250 meters below the ground. There is no way down but there is a nuke button in front of you. It says "launch a nuke that will explode right above this position." You decided to ignore it and use it to poke a hole on the wall and found stairs to the next level.

Floor 2931: Somehow there is a computer with vanilla KSP 1.12.3 installed and you complete a career mode playthrough.

-40

2010

-42

ahhh -44

This refers to the famous “twin paradox”. I'm giving a brief explanation here. A pair of twins are both astronauts. One(elder) stays on the Earth as control group, while the other(younger) goes on a spaceship to travel at 0.6c. Earth frame(pretend it's inertial lol) For the elder twin, the younger travels for 50 years at 0.6c to 30lys away, and then back at the same speed. The younger returns. For the elder 100 years have passed since the younger left. For the younger it's just 2×50×sqrt(1-0.62)=80 years. So the younger is now 20 years younger then the elder.(really) Moving frame For the younger, the travel length is 30×sqrt(1-0.62)=24ly. Total travel time is 2×24÷0.6=80 years. The elder experiences a total time of 80×sqrt(1-0.6^2)=64 years.(In the frame of the younger, the elder moves at 0.6c so time gets slower for the elder) The younger returns, and the younger is now 16 years older than the elder(emm... try to understand what i mean lol) So will the younger be 20 years younger than the elder or 16 years older than the elder? The answer is: 20 years younger. So what's wrong with our theory with the moving frame? Actually,it is true that, in the moving frame, the younger sees that time gets slower for the elder. But special relativity only applies to inertial frame. The younger has to, somehow, change the trajectory, from (0.6c leaving the Earth) to (0.6c approaching the Earth). Suppose that this is completed in a tiny "moment" in the moving frame. The younger will see a sum of 100-64=36 years passing on the elder (and the Earth) in that "moment" which is used to deccelerate and then accelerate again. So IF special relativity will be applied... the playerbase may find it hard to adjust to it, not to mention the difficulty to "find a way" to code it into the game. (Oh come on, I learned this when preparing for (China's) National Physics Olympiad)

Well IMO special relativity isn't only about differences in the coordinates of time&space... For example, in the static frame (say, Kerbol frame), the ΔV generated will differ from the ΔV generated by the same amount of fuel in a moving frame (say, ship frame). For the sake of Physics... KSP1 (and possibly real space missions) depends "immensely" on Tsiolkovsky rocket equation, ΔV=μln(m0/mk), where μ is the speed that the engine pushes exhaust fume backwards relative to the spacecraft (a.k.a. specific impulse, Isp), mo is the mass at start and mk is the mass at end. (If Isp is in "seconds", then it means "how long can the engine provide thrust equal to the gravity of something which weighs 1kg, while using only 1kg of fuel". So Isp in seconds and μ in m/s can be related by μ/g=Isp) In the classic model, this is correct. If you have an upper stage which moves in space without gravity and accelerates in a straight line, its engine Isp is 380s, it has 3t fuel and 1t dry mass, let g=9.8m/s2, then its ΔV=380×9.8×ln(4/1)=5162.56m/s. However in the case where special relativity is taken into concern, Tsiolkovsky rocket equation needs some "correction" to be Physically correct. I'll leave the process behind, but with Lorentz transformation, conservation of momentum and some calculus, you get: m0/mk=[(1+ΔV/c)/(1-ΔV/c)]c/2μ=exp{ln[(1+ΔV/c)/(1-ΔV/c)]×c/2μ} as a correct result. (This equation is correct given that μ<<c, which appears to be true for most modern thrusters) (Aclé equation, but I don't know whether that's the correct spelling or not. Also the ship has to start the acceleration from a static position, so for acceleration from a moving position, some Lorentz transformation for speed may be useful.) Taylor expansion of "ln[...]" and we get: m0/mk=exp(ΔV/μ)×{1+[(ΔV/μ)×(ΔV/c)2]1×(1/3)+[(ΔV/μ)×(ΔV/c)2]2×[(1/18)+(μ/5ΔV)]+[(ΔV/μ)×(ΔV/c)2]3×[(1/162)+(μ/15ΔV)+(μ2/7ΔV2)]+...} If we do some math and extract m0/mk out of the Tsiolkovsky rocket equation, we get: m0/mk=exp(ΔV/μ) So yes, when ΔV<<c that {...}≈1, nice and neat. But when ΔV gets closer to c, it will take some more fuel to achieve each little amount of acceleration as m0/mk increases. When ΔV reaches some 0.1c, special relativity kicks into action and makes a small difference. When ΔV reaches "interstellar worthy" speeds of some 0.5c or 0.8c, special relativity makes a HUGE difference. When ΔV goes really close to c, special relativity makes an ABSURD difference, not only about being "slower" in time and "shorter" in length, but also an ABSURD amount of fuel is required to go to that speed. (Interstellar travel can be seen as moving on a straight line without much interation with gravity, when you reach 0.x times the speed of LIGHT) Let's calculate the fuel needed to propell 1t payload to 0.8c (AND to slow it down to 0c or it will fly forever!) with different engines. Chemical: Isp=450s, a somehow ideal engine already. slowing down from 0.8c to 0 requires [1.8/0.2]299792458/(2×450×9.8)= exceeds the memory of my poor little CASIO-991. That's far more than 10100t fuel required for braking. Which means faaaaar more than 10200t for acceleration. Tip: the mass of our Milkyway galaxy is somewhere around 1.7×1042kg. Completely impossible. Nuclear: Isp=1.5×107m/s, which is the theoretical upper limit of a 6D --> 2He(7.1MeV) + 2protons(17.1MeV) + 2neutrons(16.55MeV) + 1.8MeV engine. Slowing down from 0.8c to 0 requires [1.8/0.2]299792458/(2×1.5E7)=3.4342×109t, or 3.4342 billion tons. To accelerate such a mass to 0.8c requires a 1.1794×1019t ship on a parking orbit. Don't bother to think how to get that thing into orbit from ground though... Photon/Antimatter: a concept that I had discussed in a topic earlier. It uses a different equation. Braking to 0 from 0.8c requires (5/3)t mass (1.6667t), and to get that mass from 0 to 0.8c requires (25/9)t mass (2.7778t). It may seem possible but it needs 100% efficient photon engines (putting matter and antimatter together, convert 100% of energy released to photons and shoot them exactly backwards). I don't know if KSP2 will have that. All data about mass refer to static mass, measured from a inertial frame where the object is static. Also, When the we enter the flying mode, we are in the "ship" frame. Keep in mind that special relativity tells you that "all inertial frames of reference are equal by nature". The ship moves at 0.8c. A clock on the ship ticks 5 times. But we see the clock at base only ticks 3 times in the meanwhile. (say, we are smart enough to correct deviations caused by the limited speed of light and the Doppler Effect). When we switch on our magical engine, we experience acceleration in ship frame, where acceleration a=TWR×g In the ship inertial frame(which moves at 0.8c, reaches the same place at the same time as the ship, but not accelerating), the ship experiences another acceleration a1, a1=aγ3=a×(5/3)3=125a/27≈4.630a. In the static frame(Kerbol frame), the ship experiences yet another acceleration a2, a2=a/γ3=a÷(5/3)3=27a/125=0.216a. Special relativity just makes it too complex to code&play, I suppose... To achieve a speed where special relativity is worthy of concern, we need either very advanced engines, or use entire celestial bodies to send a small probe/spaceship. (Pluto weighs 1.303E19t, and all of that has to be fuel to put into the reaction chamber...). Advanced engines may work well, and special relativity needs to be taken into consideration in that case. But with conventional propulsion methods there seems to be little need for simple relativity bucause the ship never reaches 0.xc (0.01c is great for conventional engines...). Given that KSP2 HAS Antimatter, I suppose it is possible to implement special relativity, but I don't see a very high probability.

*Not exactly replying to this challenge but..* In the summer of 1983 some F-15 fighter jets of the Isreal air force was doing routine training, when two of them CRASHED together in the air. Pilots of one plane ejected immediately. The other plane made it to an airport 16km away. They almost lose control several times on their way, but they maintained stability by... simply switching on the afterburner When the pilots walked out of the cockpit they found out that they had lost one of their main wings (They could't see the wings cuz it was blocked by the fuel mist) Imagine you are a ground staff and you see this approching your airport at twice the standard landing speed And witness this crap plane land successfully The manufacturer (McDonnell Douglas) studied this miracle accident and they concluded that, the F-15 had a very "fat" body and it can fly without wings, if fast enough This plane was later fixed and even shot down a fighter jet of another country several years later(I hope this won't be so political...) OK this may go to some asymmetrical airplane thread but the conclusion given by McDonnell Douglas was just... I think this spoiler isn't political... (The miracle did happen in real life in 1983; the spoiler is just a fiction)

I guess @ColdJ will be back

You get your juice but you don't know it was made of 5 apples all with worms inside. I wish I can go on a 1-minute round trip to Proxima b.

No. They get specific answers. What is the temperature of your oven when you make grilled chicken?

All hills are mine as long as they are still on the Earth, and therefore my profile picture. My mighty hill. (OK, take it)

Flag gets burned in the Earth's forest fires. How can you beat the Earth? I am expecting a star or black hole now.

One of China's major aerospace institutes (CAST, others include CASC, CNSA, etc.) released a feature video ~3 days ago. I've got some interesting pictures about potential future missions from the video. (most of it is about what it has done) All these are just from the video itself and may or may not be carried out in recent years due to reasons discussed above. This one is the CSS. (OK old thing, but its construction will certainly be finished in a few years using LM-5.) This is China's next-gen lunar exploration vehicle? (said to be 4th gen in the vid. It seems to contain a lander and a permanent orbiter, but it is unknown where the (promised) sample returen module is. In the video the smallest cubesat in prograde direction of the ship is decoupled in moon orbit and extends its solar panel after separation, so it can't be sample return.) This may be the future moon base at the south pole that China plans to build with Russia. Although this is an official video, it may have been made by people who are better at graphics than aerospace so a rocket with spaceplane&fairing&SRBs appeared in the back of the scene. (It looks exactly like the Americal space shuttle lol.) The buildings exposed to space and therefore potential micro-meteorolites are probably not part of the actual plan. The glass cage shown is presumably China's second moon rover Yutu-2, which currently operates in South Pole-Aitken basin. In the video it is "caught" back as an artifact in a micro-museum. The facilities between the rover and the lauchpad are possibly related to fuel or energy production. I see no solar panels so it may be a mining scene extracting water or Helium3? (This part is only video with no information-rich audio or even a subtitle.) This part also has no subtitle. It is evident that the vehicle contains a nuclear reactor and (high-power?) hall thrusters, so it may be used in manned deep-space missions since there appears to be windows on the last 2 modules. Planet Saturn. Mars (and Jupiter, not included in this picture) are shown in the background. This is the vid link if you would like to see it https://www.bilibili.com/video/BV1pq4y1M7N1

Just had a meal. Maybe @Souptime now?

news link text in Chinese (from a somehow official platform) news link text in English (from a slightly less official platform) After 92 Earth days the rover has moved 889m and transmitted 10GB of data back to ground stations. This is said to be the end of planned mission and the rover will still carry out other scientific tasks as everything on it still works fine.

I just pop in randomly. @Stormpilot

I believe this scoring rule is useful but has a loophole. If I somehow use an ion engine (i.e. RTG-powered low TWR ion thruster(s)) to slow down from an absurdly high orbit to low Tylo orbit, and then do a landing with a few stages all with appropriate TWR, this will get a heck lot of points out of the scoring rule, but will also spoil the fun. The solution may be "Everyone just do the challenge as what it was supposed to be and do not exploit anything."

Oh yeah KSP2 has antimatter.Almost forgot that. I may include this in my mod. Mankind(not Kerbalkind) now HAS sent probes(JAXA?ESA?) using solar sail, but to inner solar system (Mercury) where high DV is required and an abundance of solar power is present. And I remember watching a Scott Manley video about reaction wheels. He mentioned that a probe sent to deep space mission by NASA (voyager?) uses small panels that reflect solar light to hold altitude. Those engineers were, just too smart. I believe this is agreed with by Stephen Hawking? The exact problem I found out when writing configs. I actually mean the ship can somehow generate low-frequency photons on the way, which poses no threat the ship or whatever is in its trail.

@HyperDraco My second post in this thread! Will there be a third? Who knows?

Actually if you looked at the configs of the converter, you will find out that there is no "fauxmass"--in Newtonian point of view. But I will accept this as the official name of the fuel. Much better than Fotons. All right. I admit it.