Northstar1989

OK, so just a quick check: The "&" symbol was replaced with the "," symbol in all configs for the next release, right? (which I hope is coming out soon!) Also, were the rest of the changes FreeThinker mentioned here and later said he submitted a Pull request for, accepted? Regards, Northstar

If the planet's rotation speed is slower, the planet's gravity has to be weaker in order to create the same surface gravity value (1.00 g). Otherwise, you will have a higher surface-gravity value than before... IF the planet's gravity well suddenly becomes weaker, than any satellite in a circular orbit will suddenly be flying too fast for a circular orbit at that altitude/speed, and will fly off further from the planet! And any craft on an escape-trajectory will suddenly veer off-course from wherever it was headed! Not that it really matters- I just got a save-breaking bug that deleted all my existing craft anyways... I HOPE you've actually re-balanced 6.4x Kerbin's gravity so as to maintain the same surface-gravity as stock Kerbin or Earth (at least at the 12 hour rotation speed), Paul? Regards, Northstar

Molecular Mass of a given propellant is constant- it never changes. Therefore, the math for it is not something you figure out in-game, but rather out-of-game, and program in for any time a given propellant is used... The "Propellant ISP modifier" is accurately based on the relative Molecular Mass of each propellant. The only problem is that it doesn't interact with the ISP-cap the right way. So, currently, Hydrogen and Methane both have an ISP cap of 3000. The relationship of Specific Impulses as defined by the "Propellant ISP modifier" just needs to be applied to the ISP-cap. That's all. Regards, Northstar - - - Updated - - - It doesn't necessarily make sense to put different size radiators (or reactors for that matter) at different tech levels. It isn't like a rocket engine, where there are technical and engineering challenges to scaling it up based on the fluid dynamics involved. Once you know how to build a small deployable radiator, you know how to build a deployable radiator of ANY size... This is one of those things that Fractal_UK grasped and used to design the KSP-Interstellar tech tree. Putting larger radiators and reactors at higher tech levels is not only unrealistic- it's also just too much complexity from a game design standpoint. This is why I am a fan of the original KSP-Interstellar tech tree, and do NOT see the Community Tech Tree (which was designed by other people than Fractal_UK with different ideas about realism and game design) as a step forward... KSP-Interstellar is the only mod I use that re-designs the tech tree. I see no need to add any more complexity than Fractal_UK originally designed into the mod... Regards, Northstar

Do you know the formula for converting ISP between different propellants at the same temperature? V2 = SqRt(M2/M1) * V1 V1 = Exhaust Velocity of first propellant (directly proportional to Vac ISP, can can replace velocity terms with Vac ISP) V2 = Exhaust Velocity of second propellant (same relation to Vac ISP) M1 = Molecular Mass of first propellant M2 = Molecular Mass of second propellant So, at a given temperature, the Vacuum ISP of Methane should be the Vacuum ISP of Hydrogen divided by the square-root of 8 (the ratio of Molecular Masses: 16/2 = 8) Since the ISP-cap represents the maximum operating temperature of a Thermal Rocket nozzle, this equation holds true for the ratios of Vacuum ISP values: where Hydrogen/LiquidFuel should have an ISP of 3000, and all other fuels should be less in proportion with this value. Note that combustible fuel-mixes (such as Hydro/LOX and Meth/LOX) get additional Thrust for the same Fuel Consumption- in essence they get higher ISP than you would expect for their Molecular Mass due to the combustion reaction- but Fractal_UK handles these fuels with a unique Thrust multiplier if I remember correctly... Regards, Northstar

That's not a glitch chuckstabler. What you're describing is the way the ISP-cap is currently implemented: all fuels cap out at an ISP of 3000, due to the limitations of how high a temperature a Thermal Rocket could safely be built to without magnetic confinement... I was talking to Fractal_UK before he left, and he agree that the ISP cap should not be the same for all fuels- Hydrogen at a given temperature should/would give a higher ISP than Methane at the same temperature, for instance- but he didn't get around to implementing it. It's one of those fixes that I was hoping to eventually get around to in the Extension Config (FreeThinker, are you cool with us eventually working with me on fixing that?) Keep in mind that heavier (by Molecular Mass) fuel mixes such as Hydrolox (LFO) vs pure Hydrogen (LiquidFuel) *SHOULD* and *DO* give more Thrust for the same reactor. The trade-off for this supposed to be that they have lower ISP... Regards, Northstar

Yemo, You still haven't explained what the BENEFIT is of CTT. I never had any trouble using multiple mods like B9 Aerospace and NearFuture Technologies with KSP-Interstellar before. They simply got kicked to the "Experimental" nodes (the ones that cost 1000 Science and come after the stock tree). KSP-Interstellar is my primary mod that changes the tech tree- why would I *NEED* a more complex tech tree just to accommodate the tastes of other mod authors who think their mod is sufficiently advanced to warrant extra tech nodes? (a qualification that only really applies to KSP-Interstellar in my opinion: I don't want to be unlocking Antimatter Reactors or Alcubierre Drives at Experimental Electrics, but see no reason why a NearFuture Solar Blanket would need its own tech node when it's based on experimental technology almost ready today...) Anyways, regardless of whether myself or other players eventually switch over to Community Tech Tree (a project I am skeptical will last in the long run- every attempt to create a communal tech tree or resource base in KSP inevitably falls on differing philosophies and people breaking off to do their own thing), I feel FreeThinker has just gotten carried away with breaking up the reactors into too many new "families" of reactor... Fractal_UK created a relatively small number of reactor types for a reason- any more wouldn't really be a sufficient distinction to be worth the extra memory and part catalog clutter it would create. I *HIGHLY* doubt Fractal will be accepting of creating that many different varieties of just fission reactors alone, and honestly I'm not really either- I don't feel the costs (memory usage, etc.) are worth the (very marginal) benefits... Already I'm worried Fractal_UK will be difficult to convince to integrate the Propulsive Fluid Accumulators and new fuel types, even though he talked about adding some of these before himself- simply because he didn't create them, and is worried about scope over-reach in his mod. I don't want to do ANYTHING more to jeopardize the existing work finding its rightful place in the final mod... Regards, Northstar

That's essentially how I thought you coded it. So it seems recoil is not working as designed much of the time... (it's occurring in the wrong direction or not at all) Regards, Northstar

FreeThinker, with all due respect, not all players USE the Community Tech Tree. I don't, for one. I'm perfectly comfortable using TechManager to use the old KSP-I tech tree- why would I switch over to a new one I'm less familiar with? What would be the benefit? You really can't go around balancing what is hoped will eventually become a main part of a mod (when Fractal_UK gets back) against an alternative tech tree most people won't want to use. I say this out of concern for seeing your great work make it into the final mod- PLEASE, stick with balancing vs. the original KSP-Interstellar tech tree. I've poured some effort into this Extension Config as well (and will be trying to write up some more code for it soon). I don't want to see this work fall by the wayside when Fractal_UK gets back just because we started balancing against an alternative tech tree not designed by Fractal_UK. Regards, Northstar

I'm afraid you don't fully-understand optimal ascents Regex. The most fuel-efficient ascent is generally at Terminal Velocity, and with the new aerodynamics model (and the possibility to streamlined your designs and take advantage of the Square-Cube Law if they do it right...) your ideal launchpad TWR will go *UP*, not down. Think of it this way- your rocket weighs just as much as ever, so you still have an incentive to get to orbit FASTER (so you experience fewer gravity-losses), but a proper streamlined design will experience less drag than before for a given velocity- meaning it is to your advantage to ascend to orbit faster than before. In a theoretical, infinitely-tall atmosphere that had no Scale Height, a rocket with TWR = 2 (where the TWR never changed) would still eventually even out at its Terminal Velocity (which will now finally vary across designs and headings rather than being the same for a flat, low-density disk and a long, dense, streamlined cylinder!) but this is NOT the case on a real planet. The larger/taller and more streamlined your rocket, the higher its Terminal Velocity (and Ballistic Coefficient) and (in the case of larger, but not taller, rockets) the more safely it can quickly pitch over after launch without this leading to the atmosphere hugely destabilizing its flight path... (leading to a crash) The gap between you initial velocity of 0 and Terminal Velocity will be larger the bigger/more streamlined your rocket, and your ideal TWR on the launchpad will go up further so as to close that gap more quickly... Higher TWR will also mean you can get out of the thicker atmosphere (which reduces your engine's thrust) and get into the thinner atmosphere where your Thrust is higher (and your Fuel Flow unchanged) more quickly... Anyways, long story short- your ideal TWR (from a Delta-V perspective) on the pad will go UP, not DOWN, with the improved aerodynamics (although the ISP/Thrust fix will mean it's desirable to start with a lower TWR to maintain a controllable TWR later in the flight...) Regards, Northstar

No, you don't understand the Wikipedia article. ALL, I repeat *ALL* engine nozzles have the highest ISP in vacuum. The diagram you posted relates the shape of the exhaust jet to ambient pressure- which is always zero in vacuum. Therefore ALL exhaust streams are under-expanded in vacuum. That figure is about matching exhaust pressure to ambient pressure- which means expanding it as much as possible in vacuum. Regards, Northstar

OK, so great work so far FreeThinker! What do you need help with before you'll be ready to release the next version of the Extension Config? (by the way, I'm all up-to-date since you encouraged me to do so before, and will make a greater effort to stay updated while we work on developing this...) Also, let me know when you're ready for some code for CO2 tanks and Thermal Rockets... (I see Nitrogen, but not CO2, show up as a possible Thermal Rocket fuel- so I assume you haven't added it yet...) I can probably write it up myself, using your previous code as a blueprint... EDIT: I see that CO2 is showing up in the VAB now. It didn't show up until the very latest version (when you released that bugfix for the .DLL). Weird. Are you making changes not in the Changelog between updates? Regards, Northstar

Stock Aerodynamics or FAR? If it's stock, I really can't help you. The current stock (placeholder) system is so broken and unrealistic that there's really no telling WHAT it will do in a given circumstance (which is why they're replacing it in the next update). If it's FAR, some screenshots would help- nobody can tell what's going on just from your saying the plane is shaking, we need to see the design to see what might be wrong with it... Regards, Northstar

Most people don't heat their homes in the winter using electricity. They do it using oil or natural gas. We can actually manufacture any hydrocarbon as a long-term storage medium for the surplus energy during the warmer times of year. It's not hard to imagine large plants on the coasts extracting CO2 from seawater and using it to produce petroleum and natural gas with wind+solar+tidal energy. Then, come winter, people purchase that oil/gas just like they have always been doing, and use it to heat their homes... Perfectly-efficient? No. But if the cost comes down for Wind in particular far enough, it more than justifies the extra expense. Especially when you consider that the next-cheapest alternative, Coal (in some areas Wind is already cheaper than Coal) produces a MASSIVE environmental impact, and those economic externalities are MUCH more expensive than the cost of the kind of system I just described. Enough to justify heavy subsidies for Wind, in fact. Of course, in America, we don't seem to care much about that Coal-based pollution. Why? Because we typically build the Coal Power Plants upwind of poor or ethnic/racial minority communities, and politicians + rich people honestly don't care much what happens to "those people", just so long as it doesn't happen to them and they don't riot. This whole topic relates to "Social/Economic Justice" which is a HUGE issue in America- we dump all our economic externalities on the poor and oppressed, and then laugh when they get cancer and can't afford healthcare because lobbyists OWN Congress and refuse to allow any halfway-decent healthcare law through (and the Affordable Care Act does NOT count- it was in many ways garbage WRITTEN by healthcare industry lobbyists...) So, the NET costs of Wind are much lower than Coal, when you take the pollution into account (which by many estimates *TRIPLES* that *Actual Cost* of Coal compared to what you pay for the electricity- thanks to all the costs like pollution you DON'T pay for...) Wind/Solar in some areas, Hydroelectric, and yes even Nuclear (if you don't drive up the costs with over-regulation, which is a HUGE problem- we need Nuclear to be safe, but also not add to much to the cost with too much regulation- a balance we are finding hard to maintain...) *ALL* beat Coal on a REAL cost-basis... Natural Gas is much less environmentally-offensive than Coal, though (which is either dirty+cheap, or expensive+clean with lots of filtering), and in many ways currently comprises the cheapest form of electrical power in real costs. Wind is coming down, though, and like the study showed, will eventually solidly beat even Natural Gas in 10-12 years for sure... Longer for baseload-competitiveness, though, as the storage costs exponentially increase the higher a fraction of your electricity you get from renewables... Regards, Northstar - - - Updated - - - I love your optimism, AngelLestat, but there's a BIG piece of the puzzle you're missing... While yes, it is true, Wind power *WILL* continue to come down in costs, and ALREADY is cheaper per kwH than other power sources in many areas (don't let anyone tell you otherwise, they are ignorant or stubborn and just trying to BS you), the STORAGE costs of an intermittent power-source like Wind go up EXPONENTIALLY the higher a fraction it takes up of current grid generation... There's a reason Denmark is 30% wind, rather than 70 or 100% wind, and that's mainly it. The more variability you add to the grid, the more expensive it becomes to buffer the grid and store that excess energy during times of surplus generation for when it's needed during generation-shortfalls... Yes, Wind will EVENTUALLY become cheap enough as to encompass a larger and larger market-share, as its low costs are able to compensate for higher and higher storage costs. But by that time, we might actually have cleaner+safer Nuclear power like Molten Salt Reactors burning Thorium, and be safely reprocessing most of our existing nuclear waste to boot (CANDU Reactors are great in this aspect, for instance). Don't get me wrong- Nuclear is tricky, challenging to engineer, and in the wrong hands (lax operators or rogue nations) it can be highly dangerous. With current technology, it's just plain stupid to rely on it any more heavily than we already do (Solid Fuel Rod-based technology is very inefficient, produces a lot of waste, is harder to operate safely, etc.) and we're actually already starting to run out of easily-accessible Uranium reserves (which we need to keep for Space Programs and Nuclear Submarines, which have no viable replacement for some of the possibilities nuclear power enables!) at current consumption rates... But Molten Salt Reactors (and several other next-generation reactor technologies) are great, and will enable us to not only utilize our existing Uranium (and Uranium-based waste) *MUCH* more efficiently, it will also allow us to switch to Thorium- which is MANY times more abundant than Uranium, poses much less of a nuclear-proliferation risk, and is *NOT* going to run out anytime in the next couple centuries- unlike our Uranium supplies... Regards, Northstar

Good enough for government work. Seriously, though, in some ways using a lower Reactor Temperature actually even makes some realism sense, as if the nozzle were large enough it would still be possible to achieve the desired Vacuum Thrust and ISP with that temperature (although at the expense of VERY LOW sea-level ISP for a nozzle that large: which I guess we already have as it currently stands...) A lower-temperature reactor could also reasonably be expected to have better endurance- whereas the Timberwind reactors were only built for a relatively short period of high-performance during launch... Now, onwards to the Thrust: Atmospheric ISP relationship. We already have (thanks to Fractal_UK) a formula where Thrust, rather than Fuel Flow, varies with Specific Impulse- but we DON'T have a formula where Atmospheric Specific Impulse is calculated correctly in the first place based on changes in Vacuum Thrust (i.e. Throttle, total MW of Thermal Power available, and fuel Molecular Mass...) Could we remove the silly "ispratio" term from the current thrust calculation, and subtract (Exit Area * Background Pressure) instead. It should look something like this: Thrust = Math.Max (equation) - (Exit Area) * (Background Pressure) Notice that (Exit Area * Background Pressure) is located OUTSIDE of the rest of the equation? That's an important point about the format you need to keep aware of... You are basically adding a parallel term to the (Math.Max) function that only kicks in when inside an atmosphere (where Background Pressure =/= 0) The key thing that creates the proper relationship with Mass Flow Rate, etc. is that (Exit Area * Background Pressure) is a CONSTANT term for a given engine at a given altitude, whereas Vacuum Thrust (the rest of the equation) will vary based on available ThermalPower (particularly variable with a Microwave Thermal Rocket), Vacuum ISP (varies by core temperature, which can vary with a Pebble Bed Reactor like the Sethlans), vessel throttle-setting (throttling down should *REDUCE* Atmospheric ISP as well as Fuel Flow), etc. Regards, Northstar

Glad to have you aboard paoul! Since the stock aerodynamics revision is coming out relatively soon, and it will make for more realistic aerodynamics, I *STRONGLY* advise trying out the Ferram Aerospace Research mod now, to get in the habit of building more realistic planes/rockets... The Kerbal Engineer Redux or MechJeb2 (which includes KER functionality) mods are also nice, and will get you in the habit of designing with Delta-V in mind, which will FINALLY be a figure we can see in the stock SPH/VAB, with the new Engineer's Report feature coming out (Maxmaps said "Engineers will be learning something that rhymes with Schmelta-Vee in the next update.") Regards, Northstar

Michaelhester07, Do you have any insight into the recoil-problem? I was under the impression that the Mass Drivers simulated recoil (although I could be wrong), yet they DON'T seem to be working that way anymore. Making using orbital debris as reaction-mass, recycling momentum from returning capsules, and things like that ENTIRELY unfeasible (or unrealistic- since the Mass Drivers sometimes seem to get pulled in the SAME direction as their payload, rather than pushed the opposite way) as it currently stands... Regards, Northstar

Actually, they *DO* have equipment. And patents. And blueprints. Have you even bothered to explore around their website a little bit? They are the holders of several exclusive patents that prevent competitors from getting involved in Microwave Thermal Rockets right now. They have early blueprints for both transmitters and thrusters (and are working to refine both), and just successfully built a 100 kW Microwave Transmitter with Side Lobs Suppression (meaning it prevents any microwave power from going anywhere but towards the target- reducing costs and improving safety for ground-crews at the future transmitter-array site... Microwave Thermal Thrusters aren't particularly hard to build either- in fact one scientist built a simple experimental unit with a gyrotron built for laser-research and surplus GARDENING supplies in his lab that nearly beat the Space Shuttle Main Engines on an ISP-basis (which isn't surprising, as the exhaust gas is pure Hydrogen, and can achieve *MUCH* higher Exhaust Velocity at the same temperature...) I'll have to get you the article for that one- because that story is particularly amusing... The main obstacle for them is getting enough money to build a large-scale Microwave Transmitter array, rather than just a few 100 kW demonstration units... The conversion of power:thrust is better than 1 MW: 1 kN on the receiving end (using the Timberwind Nuclear Thermal engine designs as an example, which would have gotten 735.5 kN of thrust for 750 MW of Thermal Power with the 2-meter model, at *SIGNIFICANTLY* higher Exhaust Temperatures...), which means with just a couple dozen 100 kW demonstration units they might have enough power to lift a tiny demonstration-unit (that only carries its own mass- no payload) on a one-way trip to orbit (or at least a suborbital trajectory) to demonstrate the concept works... (keep in mind the ISP of a properly-built Hydrogen-propelled Microwave Thermal Thruster not made out of gardening supplies is greater than 800 seconds vacuum...) Regards, Northstar

I think that sums up why they weren't attempting a soft-landing pretty well. Regards, Northstar

That was my point, which you completely mis-read. 30-40 years isn't all that long a time when it takes 10-20 years just to get something like SLS, Falcon Heavy, or Elon Musk's Mars Colonial Transport Vehicle up and ready even when we have all the requisite technology thoroughly-prepared. Microwave Thermal Rockets are indeed currently at a low tech-readiness level (to the point were Escape Dynamics' first project is trying to determine how to cheaply mass-produce 100 kW transmitters so they can affordably build an array large enough to get a spaceplane to orbit, which will take at least 30 or 40 MW- apparently the decided to abandon 1 MW gyrotrons which are the current state-of-the-art...), but there are no major scientific barriers that have to be overcome, no laws of physics (or economics) that have to broken. It's just a simple matter of putting in the 20-30 years of hard work to make it a mature, TRL8-9 technology, like chemical rockets already are... Keep in mind that Microwave Thermal Rockets *ARE* a subset of rocket, though- and they still do benefit from a lot of the work already put into chemical rockets like turbopump, materials, and engine-nozzle design... It's just an introduction. The point was to whet your appetite to learn more. I can easily provide you with more links with more detailed information on Microwave Thermal Rockets. Despite your (arrogant) assumptions, lightcraft are actually much LESS practical experiments than Microwave Thermal Thrusters... Whereas a Microwave Thermal Rockets is really just an extension of the chemical rocket concept, and re-uses a LOT of the same technology (the only new components are the Heat Exchanger and the ground-based transmitters, actually), a Lightcraft is an ENTIRELY different class of vessel that is MUCH further from application than Microwave Thermal Rockets... Don't confuse early results with long-term practicality... You clearly didn't read the articles or OP carefully enough (although I might not have done a good enough job explaining it). It's PRECISELY for the reason that the transmitters are the most expensive component that you want to use a spaceplane. A spaceplane can get off the ground with a lot LESS Thrust thanks to its wings (optimal rocket TWR is >2, optimal spaceplane runway TWR is between 0.8 and 0.4), and can rely on Microwave Thermal Turbojets for a large part of its ascent- which get a *MUCH* better Thrust:MW of beamed-power ratio than Microwave Thermal Rockets, due to their much higher working-mass and lower Exhaust Velocity... If you do a spaceplane-ascent right, you don't ever even need a TWR much higher than 1 (if ever)- and you can use Methane instead of Hydrogen as a short "kicker" for a large amount of Thrust at a better Thrust:MW ratio (but a lower ISP) to get out of the atmosphere as quickly as possible once the L/D ratio declines to the point where atmospheric flight is no longer profitable... (you can also deploy a rocket on a suborbital-trajectory once you have kicked your spaceplane out of the atmosphere, if you want, and use most of the beamed-power to circularize that smaller and lighter craft, while the spaceplane glides back down to the surface using its wings and Thermal Turbojets to perform a descent with very little engine-power...) The aerodynamic challenges aren't easy, and are by far the most involved part of the process- but it's not like we haven't solved for them before. The STS proposal that led to the Shuttle saw the proposal of a large number of saceplanes, some of them capable of relatively good hypersonic performance (even if they didn't make it to space that way- but instead mostly relied on drop-tanks of external tanks and a vertical ascent like the Shuttle...) The secret is, you DON'T need a spaceplane that flies well at "subsonic, supersonic, hypersonic, and exoatmospheric" conditions- you just need something that is capable of getting off the runway... You design for optimal-performance in hypersonic conditions, and as long as the plane is capable of ascending to the necessary speed+altitude at all, it really doesn't matter how long it takes or how efficiently it gets there. This is because you can use Microwave Thermal Turbojets (which should be designed with optimal hypersonic performance in mind) for your initial propulsion, and the time it takes you to get to the hypersonic regime comes at essentially no mass-penalty because the ATMOSPHERE is your propellant up through this point, and you don't have to carry extra fuel if your plane requires a slower initial ascent due to having highly-swept wings and a high wing-load... As for the heat exchanger (you don't need, or use, rectenna devices, unless you want a small one for auxiliary electrical power- even though usable aircraft rectennas have been around since the 1960's, where their first demonstrated use was to fly around a toy Microwave-Powered RC helicopter more than 50 years ago...), it's not a particularly difficult engineering-challenge: a scientist was able to build one in his lab using surplus components, a small gyrotron built for laser research, and surplus *GARDENING* equipment from the local hardware store that had an ISP that nearly matched the Space Shuttle Main Engines- which actually isn't particularly good performance for a propulsion system than can achieve 800+ second ISP's (the story of this was in the CNET article I linked, I believe- although if it wasn't I'll definitely have to get you the correct article, as it's quite amusing...) Microwave Thermal Thrusters aren't particularly challenging- it's the Microwave Transmitters that present the real technological hurdle... They're hoping to have a sub scale-demonstration out in 20 years, that can fly around in the atmosphere, and maybe fly itself to orbit (without any payload) without any help. Re-entry and reusability isn't something that they plan to demonstrate with the early model, though- just getting something like this to orbit should be enough to convince people that it's viable... Reusability is trivially-easy for the Microwave Thermal thruster component of such a spaceplane, though- there are virtually no moving parts outside of the tubopump, and the operating temperatures are MUCH lower than comparable chemical rockets (it relies on the low Molecular Mass of Hydrogen for its high Cacuum Specific Impulse). The turbopump is the only real barrier to reusability- but it's not like that's something Space-X and others aren't already working on... I'm not going to post a 12-pge PDF on the thread, obviously. But what I *CAN* do is get you some additional links to the articles so you can read them yourself. If you can't be bothered to click on a simple URL address and read what's on the other side, you probably can't be bothered to have a serious discussion about this anyways... A toy helicopter- which weighed at least a couple kg, was flown around via Microwave Transmitter and rectenna back in the 1960's when this technology was first presented (although it wasn't nearly viable back then like it is today). Microwave Beamed Power has a MUCH longer history in aerospace science/engineering than most people are aware of... Konstantin Tsiolkovsky himself was the first to propose beamed-power as a way to fly spacecraft to orbit- although at the time much of the necessary physics of photons wasn't adequately understood to make this a serious proposal. It's not exactly something new under the sun by ANY stretch of the imagination, it's just that for the first time in world history, we've reached a point where Gyrotron and semiconductor technology is well-developed enough to make a cost-effective proposal for a Microwave Thermal Rocket/Spaceplane a reality... Some of the articles are fairly involved. I thought it would be a good start to give you guys some low-level stuff to digest. I'll post some incrementally more challenging stuff in a second, although I'm going to save some of the really heavyweight stuff until a little later in the discussion... (I could link you to some other forum threads where some of it has been brought up, though- for instance a particularly interesting article on long-distance atmospheric transmission of Microwaves by the Navy- which was looking at using this stuff as a weapon against small speedboats trying to suicide-bomb battleships...) I'm open to criticism- but you need to do your homework. I've had some very high-level discussions about this topic before- but those threads focused mainly on rockets. I started this thread to transfer the discussion over more to the advantages of spaceplanes as a better usage of Microwave Power on a MW-for-kN basis... Regards, Northstar - - - Updated - - - I'll start off by answering this question, because I have to go AFK for a bit, and the CNET article doesn't do a very good job of explaining it... Microwave Thermal Rocketry benefits from Moore's Law because the technology is inherently one of semiconductor-based electronics. Both the gyrotron/magnetron used to generate the microwaves, and the Microwave Thermal Receiver/ Heat Exchanger itself, are built out of semiconductors. The Thermal Receiver utilizes semiconductors because, when built to the right layer-thicknesses, they have some of the best pound-for-pound Microwave-absorptivity of any known material. The gytotrons or magnetrons, on the other hand, include a large number of semiconductor components that are necessary to make the transmitter work in the first place. Both are expected (predicted?) to follow Moore's Law with regards to their cost-over-time as the technology needed for manufacturing them matures... It's roughly-equivalent to saying solar panel technology should follow Moore's Law, because solar panels are also built out of semiconductors. So it's not a perfect assertation, but there is *SOME* evidence to support what he's saying... Regards, Northstar

Yemo, I value your opinion- only I think you miss the point for which the Particle Bed Reactor was made. Particle Bed Reactors like Timberwind were designed (in real life) SPECIFICALLY for high TWR and the ability to be used as launch-engines. They ALREADY have a 1:4 Thrust scaling and a 1:4 TWR nerf (so, they have 1/4th the Thrust and 4 times the mass for the Thrust as in real life) with the stats I've been aiming for, and are thus nigh-worthless as launch-engines (and only useful as upper stage and orbital engines). Nerfing the TWR again will further restrict their function to only acting as orbital engines. You have to look at the function an engine's stats make it useful for when balancing parts, rather than simply looking at numbers. In the case of the Particle Bed Reactors, they were already quite marginal as launch-stage engines in real life (real chemical rockets produce more than 4x the thrust for a comparable diameter, and have 4x the TWR) to begin with- and the nerfs I'm already OK with (keeping the mass high and only imitating real-world Thrust) really limit them to only being useful as upper stages- where a stage TWR of 0.5 might be acceptable, for instance. Nerfing them further will make them only useful once you're already in orbit... Regards, Northstar - - - Updated - - - FreeThinker, I think you're used to playing spoiled for Science Points. For myself, and most new or more passive/careful players (I mostly hang around in LEO and make an occasional Mun landing for a great deal of the game), just unlocking Nuclear Engines at all is a MAJOR achievement. The fact that in CTT it requires an *ADDITIONAL* tech-node after that is a MAJOR obstacle. It shouldn't be necessary to nerf the performance because of when the part becomes available- by the time players get to a Particle Bed Reactor (and in the case of a new player, figure out how to manage their WasteHeat) they will already be hungry for higher-performing engines than the stock NERVA- especially if they are playing with any realism mods. And when the stock aero gets revised, radially-mounted NERVA engines will become *MUCH* more difficult to get to orbit than they are now- due to the destabilizing effects of having a lot of drag on the payload stage of your rocket... Players will be eager to replace a pair of radial NERVA engines with a single stack-mounted Particle Bed Reactor, which with my more *REALISTIC* stats (still 1/4th the TWR of real life, but not 1/8th like you seem to be considering) will only produce about 50% more thrust than a radially-mounted pair of NERVA's... If I'm not mistaken (it's been a while since I upgraded any reactors), researching a tech node still doesn't upgrade reactors out in the field- only the ones you place on your NEW rockets in the SPH/VAB. So, none of this should be an issue. And the tech-progression of having Timberwind-like performance come 1 tech node after NERVA's *IS* logical. I don't think you get how long that tech node will really take most average players to unlock... It's also accurate to real life- the Timberwind Reactors only came 20 years (basically, one generation as far as rocketry goes) after the NERVA- 1992 vs 1972. That's *NOT* a huge gap in time. If anything, the NERVA engines were early/experimental Nuclear Thermal Rockets, whereas Timberwind and SNTP-like engines represent more mature nuclear propulsion... All of that sounds unnecessary to me. Currently, the Particle Bed Reactors don't unlock until fairly late in the game to begin with, and at a point where being starved for Science Points and adventure will more or less be FORCING most players to start heading to other planets... NERVA should be available for players who want to send an early manned mission out to somewhere like Duna, but Timberwind/SNTP-like performance should be available to players who wait until their space program is more technologically-mature and they are better-prepared for the challenges that actually imposes... Regards, Northstar P.S. I think a LOT of this boils down to a matter of perspective on space programs. Most people, including from my perspective yourself, seem to believe that because we HAVEN'T sent manned missions to places like Mars yet in real life, we haven't been technologically-ready for it yet... In reality, while I would say that something like a manned Mars mission in 1980 would have been a little premature, there's no reason we couldn't have carried one out in the mid-90's after we developed technologies like Timberwind/SNTP nuclear space-capable reactors, and computer-technology started to really mature... It's more a matter of budgets and political willingness in real life than technology- even I, who am an avid fan of things like Mass Drivers (have you tried my Mass Driver mod yet, by the way? It's linked in my signature...) and Microwave Beamed Power (leave those heavy nuclear reactors on the ground! This is also part of why I think it's CRITICAL we get the right relationship between Megawatts of available power, and available Thrust- because it's rather hard to build even large ground-deployed Microwave Transmitter stations in KSP Career Mode...) strongly believe that the only reason we NEED these technologies is because Congress/politicians aren't willing to fund NASA (or Europeans the ESA) to the point where a manned Mars mission would be thinkable without the cost-savings these technologies enable. Please don't nerf my Particle Bed Reactors- they're the only thing keeping my hope alive that humans in real life will someday ALSO make it beyond Low Earth Orbit...

Any new launch vehicle is at least 10-20 years away from when it's begun. That's not exactly a long time... That's a very narrow definition of "best that's been done". We've already built and tested plenty of Microwave Thermal thrusters on the ground, for instance. Why are you bringing up lightcraft anyways? The thread is titled "The Microwave Thermal Spaceplane". Please don't change the subject just to beat up on completely different technologies... It's Wikipedia, what do you expect? But it's an easily-accessible introduction to the subject for many who don't know much about it... Which clearly includes you, by the way. "World's largest laser"? Did you even bother to read the recommended introduction articles? Nobody in their right mind has ever talked about a single-source beamed-power craft. Every single proposal calls for an ARRAY of a much larger number of lower-powered sources... (which is much more reliable and affordable) I'm going to stop you right there, because that's not true. Even Wikipedia is full of articles about long-distance power-beaming technology (used for everything from weapons development to beamed-power research). Read the introductory articles, and then do some research of your own. The rest of your post smacks of having not actually done anything as simple as a Google search on the subject as well. Most to all of these issues have already been thoroughly researched, and in many cases already solved. It's true, some issues remain- but based on the way you're talking about them, we wouldn't be able to have an intelligent conversation about the subject because, no offense, you haven't done your homework on the subject. Go do some reading. I've read literally dozens of articles, reports, studies, etc. on the subject... (and my brain hurts from doing so more than enough that I don't want to put up with your unwillingness to educate yourself as well...) I'm not going to put up with you continuing to troll my threads (this isn't the first, or second, or even third time you've shown up with this kind of irritating commentary on one of my threads) so you can talk negatively about things you haven't bothered to do your homework on... Regards, Northstar

I agree with that! There are a number of storage solutions that are great: Power-to-Gas, Magnetic-Bearing Vacuum-Sealed flywheels (basically you just spin up a really large metal or carbon-fiber disk with electric motors, and spin it down with electric generators when the power is needed- like Beacon Power was attempting), etc. To say that there aren't good+cheap storage solutions we can develop is just plain stupidity these days... Regards, Northstar

Depends on how the devs re-balance the engine Thrust and ISP ratings... It means your engines will gain Thrust as you ascend. Which technically, in many ways will make the game easier. It will allow the devs to give orbital engines better Thrust in vacuum without having to worry about players using them for launch-stages, for instance (as their low sea-level ISP will make them EVEN MORE worthless for this than they are now...) Although that would be contingent on stock KSP having any real orbital engines besides the NERVA... It will make anything that gives you a boost in starting altitude- like landing on a mountain rather than in a valley on Eve- more useful. And, when multiplayer comes around, I can imagine players cooperating for some sweet air-launched rocket missions (which you can already do with the mod Flight Manager for Reusable Stages installed, by the way) with one player flying the plane back down to the ground while another flies the rocket to orbit. It will make Space-X style missions (if you have the guts to try and pull them off in stock- it requires circularizing your upper stage before your launch stage disappears by going too deep into the atmosphere while on rails- and then switching back to the launch stage and landing it...) much more useful, as these missions generally rely on more vertical initial-ascent profiles anyways (so the launch stage doesn't have to boost-back as much to return to the Launchpad) and thus spend less time inside the atmosphere. In general, if the devs balance the engines right, it has the potential to just make the game easier and more fun (AND more realistic) overall, Regards, Northstar

One last thing... All is not right down in Whoville: I know I wanted to ensure we got enough Thrust/MW for the electric engines, but... *INFINITE* Thrust/MW??? Regards, Northstar

*Chokes quietly* I play with Real Solar System 64K and RealFuels+Stockalike (which means, the solar system is 58% of real-world scale- even though most parts in KSP are only between 40 and 50% the diameter of real life, and my rocket engines only produce approximately 1/2the the thrust per square-meter of cross-sectional area as in real life). I'm not looking for performance that is nerfed against reality... Ignoring that issue for a second, and looking at the bigger picture, the reactors are already 4x heavier than they should be (the "Sethlans" is less than 1/4th the size of the 2.5 ton "Timberwind 75", yet weight 88% as much). Isn't *THAT* already enough of a nerf against real-life performance... The Timberwind engines (includes a reactor AND nozzle) had the following Thrust and mass values: Timberwind 45 Vac Thrust: 441.3 kN Mass: 1.5 metric tons Timberwind 75 Vac Thrust: 735.5 kN Mass: 2.5 metric tons Timberwind 250 Vac Thrust: 2451.6 kN Mass: 8.3 metric tons You're already talking only 28.4% the Thrust-Weight Ratio (8.52) if you scale down the Thrust 1:4 but keep the excessively-high mass (2.2 tons for a Sethlans + Thermal Rocket Nozzle, and that's not even counting the weight of the reactor fuel!) Now you want to cut the Thrust down to 1:8 instead? These reactors were built for LAUNCH STAGES- but pretty soon you're going to be getting into NERVA-like territory: engines that can barely lift their own weight... The KSP-Interstellar NTR's are based on technology from 20 years ago (Timberwind/ Particle Bed Reactors) to the near-future (Molten Salt Reactors- which are STILL 10-20 years off), NERVA are 1970's technology. There *SHOULD* be a large gap in performance between the two. And, as I stated previously, Thrust/MW ratio is based on real-world physics. If you break that, you've got nothing to go by or balance against... I *STRONGLY* recommend we stick with the correct Thrust:Megawatt ratios for the reactor temperatures and Vacuum ISP (Thrust:MW ratio targets are currently 15% higher than Timberwind because our nozzle is much larger and gives a 15% higher Vacuum Thrust/ISP...) If you *REALLY want a 1:8 Thrust scaling, then we should cut down on the ThermalPower production instead. Don't forget that Thermal Rocket Nozzles can also be powered by microwaves from Solar Power Satellites in close orbits around the Sun. If you nerf the MW:Thrust relationship to only produce half the Thrust-per-MW that it should realistically provide, then you make those a *LOT* less relatively useful... In fact, the Thermal Rocket Nozzle is used for every single reactor in the game- so if we don't fix the Thrust/MW ratio (which Fractal_UK had set *FAR* too low compared to real life), then you nerf *every single one* of those as well, and make the entire mod much less useful compared to what it should be... Regards, Northstar - - - Updated - - - To clarify: currently, the Thermal Rocket Nozzle produces 0.5648 kN/MW with a 3000 K exhaust-stream. In real life, a Thermal Rocket can *EASILY* obtain more than 1 kN/MW with a vacuum-optimized nozzle at 3000 K: the Timberwind reactors all produces around 0.98 kN/MW, and they all had small nozzles optimized for sea-level performance... (larger nozzle --> more kN/MW in vacuum) It all boils down to this, though: half the Thrust-Weiight-Ratio is *NOT* half as good. An engine with a TWR of 8 can *barely* function as a decent upper-stage (and FORGET about using it as a launch engine) after you add in fuel mass, payload, and thrust-loss to atmosphere. An engine with TWR of 4 can barely serve as an orbital engine. And just to add a little perspective... A rocket with a TWR of 1.8 on the launchpad can make it to orbit. A rocket with a TWR of 0.9? Not going anywhere soon... We've already cut the TWR to roughly 1/4th that of Timberwind (such that the reactors can no longer serve as launch-stage engines, after losing 60% of their thrust at sea-level, as the sea-level TWR of the engine itself is now only 3.4- not enough even to lift a launch stage on their own: despite their being modeled around nuclear launch-stage engines with a sea-level TWR of 26.7!) Cutting it to 1/8th (sea-level TWR of 1.7 for *just the engine*) is *NOT* going to sit well with me... Regards, Northstar