iontom

Yeah, I think there's a few mass ratios here. To start with, here are the ones that directly are measured when building a ship in the VAB: MH_reaction/MAH (MH_reaction + MAH + MH_ReactionMass)/MDry_Ship_Mass Now, I guess it turns out the actual ratios are much more complicated. Firstly, some of the hydrogen you're carrying doesn't react, it just gets superheated an ejected at relativistic speeds. There is a ratio of hydrogen/antihydrogen that gives you the amount used for fuel and the amount that just gets blasted out at relativistic speeds. Then you add stuff like relativistic mass, and it gets WAY crazier: I think here's the same EQN from wikipedia: This looks scare but might not be super hard to calculate since its just numeric, plug and go. It just changes with your speed so your TimeWarp mod may have issues. Then Page 14 and 15 have some a breakdown of nominal mass ratios. And Jesus it's complicated. Depending on your acceleration profile, your trip time can be halved, but your fuel mass cost goes up by factors of 10 or more. Now, this source is for a purely antimatter driven ship. Using a magnetic sail for braking probably cuts down the nominal wet mass by a lot. Probably more than half depending on how much hydrogen you acquire from your magscoop. You probably could also accelerate with a magsail out of a solar system if you had an ionized beam source propelling it. Or even a microwave laser would probably reflect off the sail if you set it up correctly. I wonder if you could have trapped ions in a much larger sail shape than the wire mesh... Def needs more research. It might be worth putting our questions together and emailing Robert Frisbee. Then there's the issue of scaling - hitting such massive velocities looks like it may require gigantic ships. The only viable option I've seen for this is Part Welding and changing TweakScale to allow massive ships, like that guy who made the Star Wars Destroyers. Using tools like that would need to scale correctly with the IE Mod's reactors, engines and timewarp acceleration. Navigation in these missions is really hard in KSP already too (or was when I tried it on Monday). At least, knowing when to start decelerating or using your magsail is really hard to do by yourself. An interstellar co-pilot / planner tool would really help. So many challenges! Cheers

I finally had time to test this yesterday. Been a busy few months, plus I had to figure out some issues that Kopernicus and CommNet were causing for me. I loved the new Anti-Hydrogen tanks. I'll try to think more about those too. I could ONLY reach about 0.15c, but I still was playing around w/ antimatter to matter to dry mass ratios. I mostly just threw things together to test. I'd love to see your craft designs for those! In regards to reviewing the braking force, I'll review some eqns tomorrow. The braking range sounds about right though. I wasn't able to find if you had a special tank designed to capture interstellar medium. It is mostly molecular and atomic hydrogen though, but you'd still need some mechanisms to cool and prepare it. There's some helium and dust. https://en.wikipedia.org/wiki/Interstellar_medium The harder part will be determining deceleration to mass inflow rate - so how quickly you brake vs how much ISM/hydrogen you can fill into your tanks. I think you must have this modelled a little bit already but it seems to be mostly with your special bussard engine? Theoretically you could use that hydrogen w/ any engine, but would it really be enough is the question. Also - it'd be exciting to apply a similar force mechanic to a photon sail. You've got a lot of the pieces in place for it to work. I also saw this today - looks like they might be modelling project Starshot or trying to. Keep up the awesome work!

Holy guacamole! That's absolutely incredible! It's funny that I was just checking out the forums after months MIA. (Finally built a new PC a few weeks ago) Does it include a breaking force during time warp? Cheers!

Sorry for pulling a disappearing act. Been very busy with work and some other projects. I did get a group started called OpenSpaceProgram which you should follow and put some input into when you have the chance. In another two weeks or so, I will probably get more involved in doing more quantitative modelling for this. I've been learning Python Juptyer notebooks which are really useful for this sort of work. Just let me know any hangups you want me to look into. I do like that point on temp/accel resistance. 76 km tank in KSP. Scary stuff!

I think it's a matter of comparing forces. The drag you'd experience would be related to the momentum transfer with the particles, which depends on their velocity relative to your mag scoop (relativistic momentum). ISM is both slow velocity and high velocity stuff, but all will have a relative velocity compared to your ship. Somewhere out there is probably a statistical particle dispersion we can look up - but it we would probably have to find a way to derive a function: F(ship_vel, array[nearest_stars, star_luminosity, star_gravity]) - if you're within the range of a star, you'd experience solar wind particles (more complex for binaries too). Once you hit termination shock you'd have the ISM instead, and could use the interstellar medium dispersion eqs to determine the drag force. There's also conceivably an element of randomness to this - so it's hard to plan for it directly when making fuel use plans. For the force from acceleration from fuel to thrust, I guess it depends on the rate of inflowing particles, and the rate at which you're using the newly acquired matter in the antimatter reaction versus just pushing it into the exhaust to increase the reaction mass. My gut feeling is that there's probably a velocity range sweet spot where you could conceivably have net gain from keeping the ramjet turned on. However, the faster you go, the more particles you hit, and the more relativistic mass/momentum is going to be a significant factor. Also, as are starting to find out, antimatter storage density is the bigger problem than the regular matter. For more dependable flight plans, it would probably make sense to keep the scoop off until you wanted to decelerate, and then just fill up your tanks again - but KSP is all about experimentation and we won't know until we do the math (or find somebody even smarter to help us review our math) Cheers!

Maybe in the game, but not in reality. NERVs have a pretty low ISP (5000 s). The highest ISP engines ever imagined is beamed core antimatter reactors with magnetic nozzles - and those are effectively 10,000,000 s. In reality, once you get above 0.1c you're going to experience more drag from your ramscoop than the thrust from your engines. Which makes ramscoops a great tool for deceleration, but not much else.

Cool - glad to know that the Daedalus has an effective ISP calc. Regarding antimatter storage - I still need to find some time to review and finalize tank mass calcs from the microtrap array numbers I had. I didn't have any knowledge of the trap mass. But I'd like to compare them against the numbers you are using right now. I think the issue though is that with the scaling you present - there's only an exponential trend while increasing the tank size. Once you start adding multiple tanks, the ratio of fuel to dry mass no longer scales, not even linearly. Your antimatter payload and your dry mass will just continue to keep the same ratio, since the ratio for 2 tanks or N tanks is the same as just 1 tank. Unless you are doing a calculation somewhere that I don't see. Basically - to hit the the desired cruise speed of 0.3c, you'd need mass parity if 1:1. So maybe something like if you have 8x or 10x the 40m fuel tanks, you would be able to hit 1:1 needed. Unless I'm missing something. BUT - I still need to calculate out fuel/dry ratio for microtraps and overall storage for neutral molecule positron binding, or even CNT/Buckyball containment. One of those might be a little more efficient. Still - I think this scaling ratio is always going to be the problem. BTW - somebody just posted this mod for a Bussard scoop. I like that its a functional scoop with code, but don't think it does decelleration though, and I like the model by @SasquatchM better.

Actually, I am quite okay with using it for deceleration. I really want a combination of mods that would let me have: Acceleration out of the Kerbol system using a photon sail that can be pushed by multiple lasers - possibly up to 0.2 or 0.3c Secondary propulsion using onboard antimatter reactor to add another ~0.4c in velocity to hit 0.6 or 0.7c Using the bussard-scoop for breaking against the ISM, which actually is more efficient at higher velocities - and could drop you from any speed down to below 0.1c Using the fuel picked up from the ramscoop - either use a fusion engine or the antimatter reactor to break down to the ~25,000 km/s speed Use some higher-trust fusion drives for arrival-system maneuvering, keeping a fuel budget for around 50km/s delta-V so that you can drop off deliveries to multiple planets in the new system. Using interplanetary launchpads and packing a bunch of MaterialKits + Specialized Parts, build a resource harvesting base in the new system Repeat with as many interstellar spacecraft as needed until you have a fully self-sufficient exoplanet colony that can build new things on site I really need a better computer with higher ram to handle it though. Anyway - check out Interstellar Extended by @FreeThinker - and we could totally use some help on the proper antimatter storage ratios for anybody who is interested.

Does the collector cause any drag? Bussard collectors would case decelleration for any speed above 4000km/s. Also - there was an older mod that made a ramscoop - but instead of an antenna dish they modelled a transparent magnetic field thing. It's pretty cool looking and the modder just posted the files saying anyone could use it. Cheers

Wow, yeah, it seems counter-intuitive that you need more antimatter than matter. I guess the numbers there are pretty close. I'd think you'd want 1:1 but maybe there are losses during the annihilation? (165k tons of antimatter and 160k hydrogen.) I think the tricky thing to understand here is that the mass ratio actually changes as you move faster and use up more fuel. http://www.wikiwand.com/en/Antimatter_rocket Eq.III can be integrated and the integral evaluated for and , and initial and final velocities ( and ). The resulting relativistic Rocket Equation with loss of propellant is[2][20] Of note: variable a is the original mass ratio of dry/wet. You're solving for the actual total trip mass ratio with this monster. What bother me is that they are just assuming the Isp to be the desired final velocity of 0.69c, which is m/s, instead of just determining seconds. However, since Isp is always shown here as a relation to c, it always cancels out - with the exception where you have Isp*Delta-V. But for an interstellar trip where you plan to use all of your fuel - those values would be the same. However, that's not a safe assumption to make for kerbal, because you might use a secondary propulsion method to deccelerate (IE magsails and a small fusion drive so you can dump the huge antimatter tanks). The thing to do would be to probably calculate out the max delta V for a particular stage given the amount of onboard fuel and applying an energy conversion. Now, I wish I had mathemetica right now to evaluate that monster. It might be easier to write a small program to handle it. Ultimately the "a" value and the max delta-V will be variable based on how much fuel you have to convert to energy and what the efficiency is. I'm not sure how this is moddable into Kerbal though, since from what I understand, KSP only cares about determining thrust based on Isp values. We might have to solve for the trip duration mass ratio (M_0/M_1), and use the standard 0.69 for the I_sp value, and then plug it all in, and then reverse solve for the "classical" I_sp that KSP uses. https://wikimedia.org/api/rest_v1/media/math/render/svg/41bae943b77f591d8b298ee431cc3b8736b58589 But I don't think that ALL that is needed to get the storage density and engine working properly in the game - I think it's just important for trip planning. You would have to feed in your target delta-V, and then it would spit out the final fuel ratio you should be using. And depending on how you choose to accelerate/decelerate your fuel use will be different. So if you use a laser sail or beamed energy to reach 0.1c, then antimatter to go from 0.1c to 0.5c, then magsail to brake down to 5000 km/s and fusion to decelerate the last stretch - you'd only need to calculate the fuel ratio for the antimatter portion which was 0.4c delta-V. And of course I think the Fusion Reactors have a similar Fuel Ratio calculation problem too. Any Build Assistants are going to have to be a lot more complicated. For now, I think boosting the ISP of the magnetic nozzle and determining empirically the antimatter storage capacity per cubic meter is probably the best bet for getting it to work with tweakscale. You might also at some point make multiple types of antimatter storage - since they will have different effective dry masses. A magnetic nozzle vs a microtrap vs bound neutral molecules will all have varying support mass within the fuel tank itself. Another funny thing is that the size of the magnetic nozzle isn't studied super closely in any of those studies, but maybe when calculating the thrust, have some sort of formula check the size and apply a simple modifier. You likely would want your magnozzle size to match your reactor size. Phew this stuff is tricky!

Hello! I'm working with @FreeThinker of the Interstellar Extended mod to try and get his antimatter engine spacecrafts to be more accurate. Primarily, we want to make sure we have the correct exhaust ISP and reactor output for an antimatter reactor. We're looking at beam-core specifically, but while we are at it, looking ant anti-matter catalyzed fusion or being open to even more efficient alternatives would be great. Here is the mod forum link (you can find the mod itself on CKAN) Now, there are a few designs out there in existence which we can reference as-is. However, many of these have specific mission parameters in place at the get go. They also include a surplus of mass for use as shielding against gamma rays generated from the use of the antimatter. That goes way beyond what is necessary in Kerbal, modelling shielding from gamma rays would be a a lot of work. Also, depending on the configuration of the reactor, that shielding might already be in place. Different Physics than Tsiolkovsky The first and most important thing to realize is that the traditional rocket equation no longer holds. Some of your mass wet mass is literally annihilated and converted into energy. This means that you can reach substantially higher delta-V than simply calculated from your Isp. You can read more detail from this source, but here are the basic eqs. The problem for KSP is that once you take the derivative of this to model the fuel loss, you can't solve it symbolically for the total Isp. Ship Designs There are a few different designs out there, some in the VERY early stages of NASA Tech Readiness Level, others are far ahead in fiction alone. Here's a list from Orion's Arm which I summarize below as well, and add ACF. Antimatter Catalyzed Fusion Uses antimatter reaction to trigger D-D or D-T fusion ICAN-II: A study by Penn State Picture by my friend Seth Pulsed Explosions AIMStar Solid Core - (ISP = 1000 s) high energy conversion efficiency, but very high thrust and low ISP - little thermal decay Gas Core (ISP = 2000 s) Plasma Core (ISP = 10^5 s) Beam Core (ISP = 10^7 s) Project Valkerie Project Frisbee Gamma Ray Photon Rocket Right now the mod is focused on Beam Core, Gamma Ray photon rockets are well beyond the scope of any serious study right now. Here's two charts which show the propellent/dry mass and antimatter/dry mass ratios. Beam Core is the best, hands down. For every 1 mT of dry mass, to reach 33% light-speed, you'd only need roughly 2 mT of fuel, or 4 mT for acceleration and decelleration. For Anti-Matter, for 1000 kg dry mass reaching 33%, you'd roughly hit parity. You'd want an amount of antimatter nearly equal to your dry mass. Or twice that if you need to decelerate too. Or seen this way at just direct mass 10^6 g is 1 mT Antimatter Storage Density and Energy Requirements So first, we should look at mechanisms for storing antimatter - it needs to be tight. Generating antimatter is important as well, but the mods that @FreeThinker has does a great job at that. We actually do have antimatter stuck in the Van Allen Belt, and so does Jupiter. It can be harvested. And it's already used, it occurs naturally in lightnight strikes, and PET Scans used in hospitals are actually generating positrons from isotope decay to track gamma rays being generated inside your body. Insane right? Antimatter is NOT for energy production, it's for energy transport. It is the most efficient fuel known to physics. Antimatter can be stored in a number of ways, but here are the most prominent. Antimatter can be an anti-proton, a positron, or anti-hydrogen. Conceivably you could have heavier anti-particles, or exotic anti-particles, but those are for another time. Some of those particles though, pions, are created and destroyed during the annhilation process of larger particles. Positrons might end up being easier to store, but they have much less mass-energy than an anti-proton. Positrons are 0.5 MeV, Anti-Protons are 938 MeV. Ultimately, a LOT of your dry mass will end up being just the components necessary to house the stored anti-matter. Penning Traps - generally pretty large and energy demanding, but can hold large amounts of either anti-protons or positrons. These get a lot better with superconductors. These could potentially scale up into larger electromagnetic holding cells - but it's still pretty risky to keep it all in one place. Micro-Trap Arrays (source)- "Atom chips are now being proposed for trapping antiprotons, positrons and antihydrogen." - Source Intended for positrons at the moment, but microtrap arrays are also used in Quantum Computing and a lot of solid matter physics experiments. You can trap heavy ions in these things, it happens all the time, and these microarrays are far safer. If one fails, you might have an explosion, but not necessarily a chain reaction. A microtrap array would probably be much heavier than a large penning trap, but it could still remain relatively small since you can arrange the traps in 3 dimmensions. It's hard to get a good estimate on possibly storage limits, because most of the time these traps are used in QC where you are trying to have only one atom per trap, not several. But - if you include "cooling lasers" to the mix, it might be possible to scale things up pretty large. There are no listed numbers available for max storage capacity for Microtraps in a serious large scale use - however - "It was computationally shown that each microtrap with 50 µm radius stored positrons with a density (1.6 × 10^11 cm−3 ) even higher than that in conventional Penning-Malmberg traps (≈ 10^11 cm−3 ) while the confinement voltage was only 10 V" Source Since microtraps are basically tiny coils on a wafer, once can see how these could easily scale up. Taking the mass of a positron at 9.1e-31 kg, and the number of positrons at 10V, which is 10^8, you get 1.45e-20 kg/trap. Each trap takes up 50 micron radius, which gets you to a number of 1.47e-9 kg per square meter. So the surface area required to reach 1mT of antimatter is... 6.76e11 m^2 So that's still a lot, and mostly because positrons are so tiny, but you could fold a lot of surface area into a tiny volume if you wanted to. If you stacked all of those traps linearly, you would be 41,000 km long, but only 50 nm wide. Now... I think I did my math right, but I wouldn't mind being checked. You could possibly fold that 41,000 km into thin sheets that were 100m x 100m - assuming that EVERY microtrap has a spacing of 50 nm, I calculated that you could fit the entire aparatus into a box which is 100m x 100m x 164m, or roughly a box that is 117m^3 - again, that's for 1 mT of Antimatter Bump that up to 120m^3 for posterity, and you get a figure that says you have 5.7e-4 kg/m^3 of antimatter, or 0.57 g/m^3 Now, let's say that you bump up the potential from that 5-10 V to something more like 100 V, you now would have 12 KG/m^3, because storage scales logarthimically AND folded arrays scale cubic. You also could possibly shrink the trap size but retain a similar positron count. Realistically, you probably will want more space between the cells - but you'll run things at a somewhat higher voltage because otherwise you can't store enough. The "dry weight" here would probably be comparable to an average data center, but I'll have to calc that out when I have more time. Buckyball, CNT, Physical Binding- more coming soon. Neutral Molecular Binding - look up positron dynamics, this is a very promising technique too, definately a hell of lot easier to create en-masse than a 3D circuit of microtraps that is ~100m in diameter. Here is the chart @FreeThinker put together for his storage estimates on his antimatter tanks. - I will review tomorrow - but I think splitting tank types might be a good idea, since tech level will determine storage capacity. Diameter 0.625m 1.25 m 2.5 m 5.0 m 10 m 20 m Antimatter (mg) 1695 13192,25 105538 844304 6754432 54035456 432283648 Antimatter (kg) 0,013 0,1 0,84 6,75 54 432 Tank Mass (kg) 25 50 100 200 400 800 1600 Tank Mass (ton) 0,025 0,05 0,1 0,2 0,4 0,8 1,6 Antimatter Beam Core Reactor Energy More to come on this soon - will try to derive from the charts above. Help appreciated. Magnetic Nozzle Exhaust Velocities I will expand on this soon. Basically though, it's variable based on what reactor you use, but enough sources out there claim an upper limit of about 10,000,000 ISP, while some only predict 100,000. ISP, Exhause Velocity and Delta V are again related, but not via the traditional ratios of the rocket equations. See above. ALRIGHT - this is my first draft - I'll update this first post with relevant information as we revise things. Also - I'll probably post another thread for the MagScoop Sail too - since that can handle the bulk of deceleration (interstellar 'wind' drag) andthus cut your fuel needs down by nearly half.

So I was thinking about modding your magnetic nozzle when it's attached to the beam core reactor. According to Atomic Rockets the Isp is supposed to be 10,193,680 s but you currently have it as 100,000 s (source) Can you just update the part config file? Or is there a more involved process because of tweakscale or knowing what it's attached to? Also - is there a maximum ISP limited by the game itself? https://github.com/sswelm/KSP-Interstellar-Extended/blob/master/GameData/WarpPlugin/Parts/Engines/MagneticNozzle3/MagneticNozzle3.cfg atmosphereCurve { key = 0 100000 key = 0.99 0 key = 1 0 }

Wow! You're really knocking it out of the park today! Thanks for solving that radiator problem. Will test tonight.

I'm got this issue with every time I load a ship from the tracking station, all my radiators explode. Not just some, but all of them. I'll have to find a way to unit test later this week with other mods - but since all the radiators are from this one I thought I'd just bring it up and see if anybody else has encountered this. Also, something seems to have happened to the magnetic nozzle in 1.13.3, it doesn't apply any force anymore, in warp mode or otherwise. Did you ever bump up the ISP on that or are there preset limits on that?

Cool! You might want to slap down an MIT license since those are pretty robust. https://opensource.org/licenses/MIT The crewmen of the KSV Goliath thank you for your service! This is just the arrival stage (D-T Vista and 16 plasma thrusters with ~50k dV) - the interstellar beamcore-magnozzle stage (The Kolossus) is even larger - mostly fuel, and I'm still testing it (it is super low thrust, high ISP, and hopefully has a dV high enough to get to at least 10% c). A bussard magscoop would help almost halve the total fuel needed since it should assist in most deceleration (as a magbreak) and then provide fuel for a final course correction and decell burn when entering into Valentine's SOI. Cheers!