# Cunjo Carl

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## About Cunjo Carl

• Rank
Rocket Fancier

## Profile Information

• Interests Science. All of it!

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1. ## Guess Who Will Reply Next?

@tseitsei89 'Sup! Still around, just checking for mentions for now. My family saved up for a Switch, which we've been playing, and I'm programming a video game. I'll be back to KSP full on again soon enough. I don't think I'll ever escape . Good to hear from you, by the way! I'm gonna try for @Ultimate Steve!!
2. ## Orbital calculation headaches

I'm in! My free time is pretty sparse, sadly. Do you have availability tonight 9-10pm PDT (4-5am GMT)? If not, I can try to swing a time this weekend. Just like anything, it's tricky stuff when you first get going, but gets easier as you play with it. Hopefully I can get you started! What language program, btw?
3. ## Orbital calculation headaches

I think I finally have it boiled down to the base concepts. It seems like @Maltman is already set, so I'm a little hesitant to post it here, but without kicking a new thread (and where would it go?), I'm not sure where else to put it! Well, here we go: Orbits for those finally tired of going round in circles r(θ) = p/(1+e*cos(θ-α)) This equation tells you the entire shape of your orbit in terms of 3 constants, which you can calculate from any point in your orbit. Those constants determine shape, size and direction: e "eccentricity" which defines the shape p"semilatus rectum" which defines the size α "longitude of periapsis" which defines the direction the short end points. Tasty elements of orbit like apoapsis and semimajor axis can all be found as simple relationships to these 3 constants, and in the next few paragraphs we'll see how these terms arise from from the fundamental concepts of an orbit. For a refresher: Orbits work by having you spin 'round a planet, and your centrifugal force holds you up even though gravity pulls you down. If these two forces happen to balance eachother your orbit will be a pleasant circle, but if they're out of balance, you'll bounce back and forth between them like a mass on a spring. At periapsis, extra centrifugal force becomes upwards momentum and you rise, then at apoapsis the higher relative gravity becomes downwards momentum and you fall. Then the cycle repeats, and because it happens the same way every time your craft orbits in the same shape every time. So the shape of the orbit must be based on the forces that make it happen. Let's see how. Cheat Sheet: 1. Eccentricity: The Shape e = sqrt[ (ω*PUp/FG)2 + (FC/FG - 1)2 ] The eccentricity measures the ovalness of an orbit, and to rephrase the picture painted in the intro, it captures this cycle: FC >FG ... we go up ... FC <FG ... we go down... [repeat]. So, our constant 'e' needs to be able to catch the essence of this at any point in time. It handles this by adding these two squared terms: (ω*PUp/FG) , which is the upwards momentum relative to the force of gravity (then multiplied by the rate your angle is changing to make the units work out right... <waves hands>). Any amount of upwards/downwards momentum causes imbalance, but the amount is relative to the gravity it'll be pushing against. (FC/FG - 1) When centrifugal force and gravity are equal to eachother, FC/FG becomes 1, and the term falls to 0. As either becomes greater than the other the term gets a greater and greater magnitude. Since these two things are 'added in quadrature' (a2 + b2 = c2 hypotenuse style), it doesn't matter if the terms are positive or negative, it only matters how big they are. And with this, all possibilities for imbalance are captured and brought together, and can be measured anywhere in the orbit! 2. Semilatus Rectum: The Size p = r*FC/FG The semilatus rectum measures the size of an orbit. It tells us the radius your orbit will have in that single moment of the cycle when gravity and centrifugal force balance. We can measure what this magic radius should be from anywhere in the orbit by taking our current radius and multiplying it by a fudge factor: FC/FG . Why? By serendipity, FC/FG happens to be proportional to 1/r, so whenever our radius increases, the fudge factor decreases by exactly the same amount. The product is the same as our radius when FC/FG = 1, or in other words, when the forces balance. In this way we can measure this special radius from any point in our orbit. 3. Longitude of Periapsis: The Direction α = θ - arctan( (ω*PUp/FG) / (FC/FG - 1) ) The Argument of Periapsis measures the direction (angle) of our orbit's periapsis relative to some pre-chosen galactic standard. Notice the (ω*PUp/FG) and (FC/FG - 1) terms are just the measurements from before for how far out of balance we are through either up/down momentum or imbalanced forces. Their ratio tells us where we are in the cycle, and the arctan turns that information into an angle. That whole piece tells us where the periapsis is relative to us, so when we add it to θ (which is where we are relative to the standard) we get the longitude of periapsis: the angle our periapsis points relative to the standard. Because it's always relative to where we are, we can figure out the direction of the orbit from anywhere along it. And that's it! Now we know the shape, size and direction of our orbit we can plot it or gather other information through simple relationships. I hope it's brought some insight to the nature of these seemingly ineffable constants!
4. ## Sinking in the ocean?

Did you happen to not use the chute the first times? I'm pretty sure the chute loses its mass after disappearing when you land. So if you landed it with mods the first times, it might make sense that it sank then and not now. Best of luck!
5. ## Orbital calculation headaches

@xendelaar Thanks! In retrospect, the whole derivation from base principals may have been a little overkill ... Hopefully it makes for some nice food-for-thought! Thanks for checking through, by the way. I did go back and finally solve for the standard orbital parameters (like the positions of apoapsis, periapsis) in terms of initial conditions, and just editted it in after the original derrivation of the orbital equation. Though I call it "a bit spaghetti" in the post, I'm actually surprised how clean the equations wound up now that I've started going back to look over other people's derivations (like wiki). Eccentricity is a fairly complicated little convenience variable, so an equation that can catch it from conditions on any point of the orbit will necessarily be a bit complicated. In the end it was all pretty fun! Please let me know if there's any questions, and I understand if it was a bit... beyond what's directly useful . Cheers! Oh, @bewing, I'm burning with curiosity now. Do you happen to know how KSP goes from position/velocity to the orbit?
6. ## Excitement About Dots

My favorite quirk from the migration is when you occasionally see people coming back after a while with, like, a thousand posts and 20 rep. It holds a nigh-mystical status for me. In contrast it seems like you were a rep grand gate crasher . . Also, it's too bad there's a 5-dot hardcap, or you and @Red Iron Crown would definitely be up to 6! Yeah, right? I'm pretty sure I'll won't be seeing that 5th dot 'till 2020, so figured I should throw a little party now while I had the chance! Your new avatar is much more.... uhh .... evocative to your alias . You're getting close on the 5% returns run- Best of luck finishing it out! That'll be a heck of a thing to make a fourth dot out of.
7. ## Orbital calculation headaches

Hmmm.... This is a thing I've wanted to do for ages! My goal is to provide the math for @Maltman's request with high school level math/physics concepts (the kind I work best with). It'll be long, but hopefully intuitive and informative.
8. ## My craft keeps spinning...

I'm pretty sure it's intended. Alteast, I've been using this for ages to keep my craft upright when landing a rocket on sloped ground. Often you'll land on a slope, then you want to hop out to say plant a flag, but SAS will turn off if you do and your craft will tip off balance due to gravity, and the whole thing goes pear shaped. So, you turn off SAS and set trim to hold your craft upright. Then your Kerbal can safely hop out and do their mission while the manuevering jets / reaction wheels keep the craft standing tall. You just need to be careful to not mix this with active SAS, or you'll get a funny thing I call the simon says glitch, where the craft mimics your motions, but that's another story. Yep! One thing you may not have tried yet was the content from my answer (atleast it's not clear from your posts). Did you try turning off SAS before holding alt+x to clear trim while the kerbal is still in the craft? In the present version, you can set trim with SAS on, but you can't clear it. I believe this is a new bug since v1.0.5, but it's easy enough to work around for now. If this doesn't happen to work for you, feel free to send one of your save files, and I'll give it a try on my pure-vanilla ksp and see if it reproduces on this end! I haven't been able to reproduce trouble otherwise, save the one HvP cured for me. Hopefully we'll get you going too by hook or by crook. EDIT: Trim will tend to build up on your craft if you're maneuvering while phys-time-warping. The phys-timewarp involves alt+> , and maneuvering is WASD. Together, they make alt+WASD, which sets trim. This can also happen to me a lot if I'm using rails time warp to halt rotation while doing similar silly things *cough* I mean, purely dignified things! You then need to go and clear that trim before hopping out of the craft. It's not ideal, but it's a funny result of the way the controls got laid out. Perhaps this happened for you?
9. ## Excitement About Dots

A place for the occasional Dot Hype As you post, your account will accrue dots at infrequent but regular intervals. In a lot of ways they're not too exciting for their own sake- quality over quantity for posts! Still, they make for milestones that can stand for quite a lot. For everyone, there's a lot behind each dot~ For me, I'm in a place where I have free time for a single hobby: KSP + the forums! So that fourth little circle kinda represents my free vocations over nearly a year. That's a lot of weight! What went into it? ~40 challenges (a few of which I got to host) Math galore Offering occasional help in the gameplay questions board, with a habit of making posts way too long A couple hard-earned KSP firsts, and finally... More exclamation points than are healthy in a lifetime, let alone a single year! It was a good year. I'm looking forward to another one. And on that note, I can announce with great excitement that my post-count is on track to catch up with Sal Vager's by mid 2051. See you then! I realize this is a little conversational for the Network board, but... What's in your dots? For the old timers, was there one that stood out or felt momentous? For new comers, what kinds of things are you going to try to cram into the next dot?
10. ## Mun Problems

@Spaced Out Mun's a tricky one! There's precious little flat ground, and it's very difficult to tell from orbit how slopey your landing site will be. The good news is there's a half-dozen solutions, but none of them are magic bullets. Hopefully they'll give you a starting point for thoughts on new designs! Also, unless you have a play-style reason against, I'd say don't be afraid to test your craft ideas in a sandbox mode with cheats to get a feel for things. Making the idea-design-test-result cycle quicker can make a surprisingly big impact. No-tip lander options 1. Scout ahead. Send out comsats and rovers to scout out landing sites in advance. Finding flat-ish ground can really make all the difference 2. Broaden the leg-base of your lander. Depending on the size of your craft, you can replace taller fuel tanks with a few more stout tanks attached radially near the bottom. You can then put legs on these to make a squat, stout craft which will stay upright even on the steep slopes. These tanks will typically need aerodynamic cones for launch, but you can place your legs directly on these cones, so it's generally not a big deal during construction. 3. Increase springs on legs. If you're on a slantly slope, a higher spring constant will keep your rocket more orthogonal to the surface, rather than sagging downhill and tipping off balance. They also make you sproing off the surface like a super ball when you're trying to land, but you can't win 'em all! 4. Add tons of maneuvering. With enough reaction wheels (anywhere) or manuevering jets near your rocket top, you can just let your rocket lay flat to land and then sit up off the surface when you're ready to go. This works better on smaller, stouter craft, where the 1.25m reaction wheel really works lovely for its size, and the torque required isn't too vast. On larger craft, a couple jettisonable twitches near the top can serve a similar role. 5. Use airplane landing gear rather than legs. They naturally stick out, rather than almost straight down so it's much easier to get a broad base with them! Just make sure to account for the added weight, and pull them out of the tank like they want to be when you first place them. It looks a little silly, but it works nicely. Don't forget to apply the brakes! 6. Go to Minmus instead. *cough* It's got lots of nice flat places for easy landing, and is generally a much nicer trip. It's harder to get into its SOI, though. Reentry from Mun options 1. Multi-pass through the upper atmosphere ~35-45km. This will bleed off the speed slowly, and create less heating all at once. The downside, of course, is it'll bleed off the speed slowly. I tend to put my final pass in the 22-28km altitude ballpark. 2. Lots of empty fuel tanks can help slow you down if your trajectory isn't too steep; this works well with the multi-pass. In this case, it's best to fly 'broad side of the barn' style to catch all the wind you can to slow down. For this, make sure to bring plenty of batteries, or have a way to recharge between passes (solar panels). Especially in this case, you can use body lift from your craft to control your trajectory. Making your craft a front-slash into the wind will make it lift up. 3. Retro-boost before entering the atmosphere. By bleeding off a few hundred m/s, you can often make easy work of an otherwise tricky reentry, or save yourself a couple passes. It wastes deltaV of course! If you happen to have extra fuel in the tanks, I'd say no harm done. 3. Use heat shields. In this case, you wouldn't so-much need to use them for their ablator, but instead for their high thermal tolerance. By removing most of their ablator, you can reduce their impact on your deltaV budget. The downside of the heat shields is they're very slippy aerodynamically, so you won't get much upper-atmosphere slowing with them. This can actually turn into a downside. 4. Put your kerbal in the service bay... There, I said it! Command chairs in service bays are so effective at reentry, that many consider them cheaty. I consider it funny! To be honest, it's probably best to avoid this for your first journey, but be aware that it exists. 5. Use fins as makeshift airbrakes. While this doesn't work with basic fins, structural D wings can be used as makeshift airbrakes from Mun return velocities. It's considerably more difficult than the other options, though. 6. If you're in the lower atmosphere but lawn-darting down to Kerbin, you often have a better chance of survival out of the craft than in. Bail! This will always work over water, and works maybe half of the time over land. It's KSP, so there's of course other options for all these, too. Hopefully something sounds fun and useful for your case. Best of luck! Let us know how it goes. edit: woops, didn't notice others posted while I was typing in little bits here and there. You can post images by: 1. Press the Print Screen button (or your computer's equivalent) while looking at your craft in KSP. 2. Alt-tab out and open Paint (or your computer's equivalent). In paint, press ctrl+v to paste in the photo. 3. Save it as a jpg. 4. Go to an image hosting service (imgur is this board's favorite, but I like Postimage for its simplicity) 5. Upload your photo to this site, and it'll provide you a link. 6. Paste that link into your post, and it'll appear as a photo like magic!
11. ## Realtime Career Mode Speedrun

Hey! So I've actually been running this challenge again for a while now. I didn't want to spam the challenge board with updates while I'm the only entrant, so I've been making my incremental updates off in Mission Reports. That said, I've recently hit some major milestones in progress, so I'm bringing along the highlights. 1. How do you earn enough science to make a Mun launcher in 8 minutes? A: Be very picky about which science you collect. Take only the juiciest bits and rocket on! 2. How do you get 1.5M funds for your interplanetary extravaganza with a single flight? A: Figure out the World's Firsts contract system. 3. How do you gather 3000 science in 20 minutes when you only started the game 20 minutes ago? Make a very fast biome hopper (pictures link to lander video) Also, if you fly like me, crash once or twice! 4. All together now! 5. What are the limits of practical low-part/low-cost launchers and low-mass aerobraking return craft? A: Clusters of kickbacks and twinboars work a treat, and nearly-ablatorless-heatshields make for some wonderfully efficient returns. (pictures link to craft video) 6. Where to go next? The whole solar system's our oyster. I've routed it so each craft can visit 3 bodies on a trip (eg. Laythe, Bop, Eeloo), so the speedrun can be finished out by 4 of them plus a special one for Eve. Of course there's a lot of work left! The next big question is how to setup interplanetary transfers quickly? Time spent twiddling maneuver nodes adds up fast... Welp, thanks for reading. See you in a couple more months!
12. ## Do something nobody has done before

@Overland Will a seafloor elcano train be next up? @Kergarin I'm always dang impressed with your work. Especially the stuff on Eve! Also, I dig the new emblem. I think at the moment that this is stock KSP's fastest manned non-space-plane. But in any case, I'm the first to achieve level aerodynamic flight traveling beyond escape velocity on Kerbin. Just to put the cherry on top, I did it going West! While the shots in the slide reel show a large SAS wheel, it was replaced in later versions with a 2.5m service bay for cargo. The idea was to release probes to interplanatary space right from the comfort of Kerbin! ... but ... The probes kinda explode as soon as they're released. Yeah I shoulda predicted that. Still, the plane's neat! It features: An inflatable nose cone Pretilted wings, designed to hold the plane down 100% reuseablility Gentle aesthetic clipping A beautiful view (of fire) Slide Reel Because the upwards centrifugal force and downwards wing 'lift' both increase with speed, the plane has a lovely broad velocity range where it operates smoothly. The maneuverability also rises with speed, so the plane can be crept higher and higher (into thinner atmosphere) as it speeds up to prevent firework impersonation. Its primary limit right now is fuel!
13. ## Duna Mission: What's it take?

@grafdog1138 What does it typically look like? It's funny, everyone here does things a little different, but we all get there in the end! As for how my trips look... A much-more-massive-than-necessary rocket does a vertical launch at sunrise... any 'ol sunrise! Clusters of kickbacks and drop tanks peal off the thing as it screams straight up to interplanetary space. For a Duna trip, the core rocket would be composed of a skipper followed by a set of 3 terriers, the outer two staged on radial decouplers (everything tuned to TWR ~1.5). The top can just be a standard pointy pod. The craft would push just out into interplanetary space, and then I'd make a maneuver node (in solar orbit) with just enough prograde to put the craft onto Duna's orbit. By sliding the maneuver node around, you can find the time when the burn will put you into Duna's SOI (you can find your window). Make the burn, and a couple weeks away from Duna, make a 'correction burn' manuever node to put you on course to whatever part of Duna you'd like to visit. For a first visit, I'd recommend having the periapsis at ~10km off Duna's surface. You know, the poles are nice to visit... bleak, all be. I'd normally aerobrake using body lift from the rocket to maintain a ~7km altitude, but for a first trip I'd recommend just using the Skipper stage to bleed off extra speed in the upper atmosphere (down to 1000-2000m/s), and then use it to control a pleasant descent, finally dumping the thing a little ways off the ground. The 3 terrier craft will be much more pleasant to land! My personal recommendation is to use the small landing gear over the medium landing legs, but that's just me. In any case, the outer two terriers can be put on 1.25m tanks topped with the big blue parachutes. Make sure to set them to open as high as possible in as low pressure as possible! While these parachutes won't slow you down enough on their own, a little kick from the engines just before landing will ensure you don't turn your trip into an extended impact test. Some extra reaction wheels really help at this stage. Just make sure to bring some extra batteries for them- best of luck and remember there's no shame in alt+F9 'till you can stick the landing! You can jet pack on Duna, but only barely. Pop on out, enjoy the fresh rarefied air! Plant some flags, sing some songs... sure maybe do some science. For the trip back, I am once again a fan of the vertical launch. If you just nip yourself outside Duna's SOI, you don't need to worry about what direction you're flying. Just use the same make a node and move it technique from before. For the trip back in to Kerbin... everyone has their own tricks for reentry. I'm a fan of heat shields with their ablator removed, but you'll find all sorts of ways. And that's about that! So. Brass tacks, what's it take? Traveling to Duna becomes "easily" possible once you get access to the science nodes that cost 45-science as well as the following 90-science nodes: kickback+skipper (heavy rocketry), fuel cross feed (fuel systems), the mini solar panel (electrics), and the big parachutes + medium legs (landing). I put easily in quotes because no matter what, everything is harrowing the first time you do it in KSP.... That's the fun! The mission will be easier if you have the next tech level higher in each of these, but I wouldn't consider it a necessity. For facilities, I consider the following to be a good point: Launchpad level 3, VAB level 2, Tracking station level 2 and Mission control level 2. It's totally possible with lower upgrades, but this is the point where you won't be fighting the system. I hope that's enough to get your brain tinkering! If you happen to want more specific information, it'd be handy if you let us know what kinda tech level you're at, and send us a snap shot of one of your ships. so we can get a feel for your building style. Best of luck, and let us know how it goes!
14. ## My craft keeps spinning...

@HvP Nice! Well sussed, you got it for me. It was ladder drive! Between this and the "turn off SAS before holding alt+x" advice hopefully this will get it for our OP as well.
15. ## Multiple Flag Designs?

@Npreadr You can also add your own flags by adding a .png picture file to the following folder: Kerbal Space Program / Game Data / Squad / Flags / The preferred size is 256x160 pixels, but it'll stretch things to fit. Also, you need to reload ksp for them to appear. Now you can spread NyanCat to the cosmos! Or, whatever other picture may be near and dear to your heart. Have fun!