Northstar1989

Please, please, please *stop* making that Straw Man argument. Comparing KSP to Orbiter, with *or without* increased realism, is complete nonsense, and I do think you know better than that. Orbiter is a game that has silly-stupid limits on what players can build and design, and THAT is what makes it a terrible game- not the high levels of realism. KSP is a sandbox game with very free-form play, and THAT is what makes KSP a great game- not the low levels of realism. Don't take this personally, but I think most likely the (real) reason you're resisting increased realism is because you've become accustomed to the unrealistic features of the status-quo, and you don't want them to change because that would make you feel like a newbie again. Honestly consider, did you ever expect the current aerodynamics system to work as poorly and unrealistically as it does when you first started playing the game? Didn't you have any previous knowledge of how flight actually works, that was completely contradicted by the broken placeholder system in KSP? And a placeholder it is- the devs have been *very* clear about this from the beginning. Some of the same principles can easily be applied to something like fuel mixtures. If you just picked up KSP today, as a new player, you wouldn't expect every type of rocket to magically work off one miracle-fuel with all the density and boil-off advantages of hypergolics and all the ISP of Methane or Kersosene, rolled into one. The first time you try to build a Space Shuttle, you *quickly* realize that the fuels in KSP are *far* too dense, but have much too low of an ISP compared to the LH2/LOX in the Shuttle's External Tank. The first time you try to build a suborbital rocket, and it has enough fuel to take you all the way to orbit, you realize there's something off with the fuel balance (or with the size of the planet and thus the Delta-V it takes to get to orbit in the first place- although it took me quite a few months to realize just how far off KSP's scale was from the real world when I first started playing, I must admit...) KSP isn't more fun or intuitive for its unrealistic, over-simplified, often placeholder systems. It's a game about rocket science- so we EXPECT it to be extremely challenging. I was actually rather disappointed when I first started playing KSP, and found it didn't quite push me nearly as hard as I had come to expect from sayings like "it's not like it's rocket science" and such... Don't get me wrong, KSP is an awesome game with lots of cool moments- but the unrealistic features detract from that immersion, if anything. Back to the point- if the devs added 3 meter command pods, I would want 5 meter or larger fuel tanks and engines to stick under them (or a stock Procedural Fuel Tanks system *gasp*). And if I had 5 meter fuel tanks, I would want to be able to fill them with low-density, high-ISP fuels like Liquid Hydrogen + Liquid Oxygen (especially with the upcoming weight-limits on your rockets until you upgrade the launchpad: I might want to use these fuels to bring down rocket mass for earlier in the game. This would add more flexibility and strategy to early rocket design...) If you give a mouse a cookie... Regards, Northstar

The math doesn't work out quite that simply. For starters, Squad uses real-world masses for half-sized payloads (the 1-man capsule is a Mercury capsule analogue, and has the correct mass for one- but has a fraction of the volume, making it much denser...) Beyond that, a larger diameter rocket can safely be built to a taller height (and thus contain more Delta-V) without wobble. Also, if you start applying realistic aerodynamics (like FAR and NEAR already have, and stock may someday have soon- as the devs have announced aerodynamics will be getting an overhaul) then a larger rocket has a better ballistic coefficient due to the Square-Cube Law, and thus experiences relatively less aerodynamic drag. If you add fairings, then you can enclose exponentially more volume relative to fairing mass the larger the rocket the fairing sits atop (a 5 meter diameter fairing in a conical shape 5 meters high encloses 8 times the volume of a 2.5 meter fairing 2.5 meters high, for around 3 times the fairing mass...) All in all, when it comes to rockets, bigger is better. Between the reduced-scale of parts in KSP, the use of real-world payload masses (and thus unrealistically high density- the 1 man capsule might as well be made of lead), the unrealistically low ISP limits (Hydrolox can achieve ISP's of over 480 seconds, stock KSP never hits 400 seconds with the best engines), and the unrealistically high fuel-densities for the ISP you *do* have; KSP's balanced is totally messed up. The unrealistic features actually make for a *HARDER* game, not an easier one- and the effects of these errors will only become more pronounced with aerodynamics and re-entry heat. Regards, Northstar

Hi Raptor, Fixed that bug, only to update to the 8.2 release and get this one: Notice the ISP on the Meth/LOX engine? (293 sl - 357 vac) It's not what it was re-balanced to. In fact, it's lower than in unaltered KSP-Interstellar... Regards, Northstar

The final price is MUCH higher when you include other services. I believe it comes out to around $8 or $9 million/ton with Space-X? The figure of $10 million/ton *was* indeed based off Atlas/Delta rockets from everything I could find, though. The cost-estimate of $6 million/ton for Microwave Thermal Rockets already includes all those additional services, on the other hand. So it's still a bit cheaper in its most basic form. And with Microwave Thermal Spaceplanes, you can bring that cost a *lot* further down due to reusability and increased payload capacity, perhaps by as much as an order of magnitude (true spaceplanes, as opposed to shuttle-type designs, theoretically have much higher maximum payload capacity per kN of thrust in their engines: which is the major cost-determining factor for Microwave Thermal propulsion, as determined by available MW/GW of beamed-power from the ground...) In its most basic form (disposable SSTO rockets) it's a superior but not massively game-changing option for a launch system. However, Microwave Beamed-Power truly shines when it's used in Microwave Electric propulsion schemes (for the orbital stages of rockets), drastically reducing the total payload requirement to reach GEO or beyond with a certain satellite/spacecraft design, or with Microwave Thermal Spaceplanes: which can reach orbit with between 1/2 and 1/3rd the amount of beamed power, and *drastically* bring down costs due to their easy reusability. Even if you simply scale-up the Microwave Thermal Rockets, you should achieve economies of scale. Remember, the cost-estimate of $6000/kg assumes *absolutely no economies of scale*. It's based on the current Gyrotron market-price of $2 million/MW. If you were purchasing a thousand or more of these units (1000 units is necessary just to get 1 ton of payload to LEO per rocket-launch, and is part of the basis of the $6000/kg cost-estimate), you could almost certainly get a bulk-discount on the Gyrotrons, due to being able to cut down profit margins a bit (Gyrotrons are currently a type of highly-specialized equipment sold under a high-profit sales model) and mass-produce the Gyrotrons instead of manufacturing a small number of units in specialized workshops (currently maybe only a few dozen 1 MW units are made/sold worldwide each year...) The small scale of a 1 ton-to-LEO rocket is also what drives the SSTO launch profile. Staging is a cost that does not scale the same way as rocket size (it becomes *relatively* cheaper with larger rockets)- it would actually *increase* costs to try and stage a 1-ton payload-capacity rocket, but it would *reduce* costs to stage a 10-ton payload-capacity Microwave Thermal rocket... Finally, Microwave Electric propulsion is just an *amazing* orbital propulsion system. Currently, electric engines are designed under the assumption that the most power one might possibly have available is 200-250 kW (and probably a lot less). However, the cost and mass-per-kg of many types of electric thruster comes *drastically* down when scaled to higher power-levels (this is especially true of Magentoplasmodynamic designs). Consider that, and then consider that the smallest economical Microwave Beamed Power system would provide nearly an entire Gigawatt of available electricity (and for a *fraction* of the onboard mass of a 250 kW solar array). That's a huge (4000-fold!) increase in the amount of available power to play around with in electric engine designs, and for a *reduction* in the [onboard] mass vs. even a much weaker solar array... Regards, Northstar P.S. NASA is already designing Mars missions around a theoretical 250 MW nuclear reactor and scaled-up VASIMR propulsion system (which has *much* lower ISP than many other types of electric thruster, but much higher thust-per-kiloWatt...) and an onboard nuclear reactor (which might never happen, for political reasons). So I hardly imagine they would reject a much less expensive (and politically safer) mission proposal that relied on accelerating to Mars with 1 GW of Microwave Beamed Power from an Earth-based array already utilized to launch rockets/spaceplanes. And, if you used a Cycler Ship instead of a "traditional" mission architecture, you could drastically reduce crew times in orbit- as the 250 MW Vasimr design assumes *over a month* or acceleration-time at each end of the journey (which could be performed on a previous, unmanned initial cycle with a Cycler Ship). A Cycler trajectory also only takes 5 months on each manned leg of the journey (you use a different Cycler ship to get back, with a 5-month return-leg), whereas the 250 MW Vasimr proposals rely on crew spending nearly twice as much time off-planet (thanks to the long acceleration times, but a shorter surface-stay on Mars)...

A Thermal Turbojet isn't *necessarily* expensive, unless you pre-cool it. Pre-cooling *does* allow you to operate the TTJ up to much higher speeds, and add a LH2/Atmosphere stage in between the Atmosphere-only and LH2-only stages, like I suggested. But it's not strictly necessary. As for the Cryogenic fuel-production facility, that cost isn't exactly new. We already have plenty of capacity in those already built up. Since Microwave Thermal Rokcetry actually reduces the amount of propellant mass necessary to get each ton to LEO (although it shifts mass from LOX to LH2, resulting in a net increase in LH2 demand), it shouldn't require a whole lot of new capacity to be built... The cost of getting a chemical rocket to orbit isn't fuel. It's in engineering and construction of space-grade chemical rocket engines, mostly- and Microwave Thermal Rocket Engines are comparatively cheaper (at space-grade engineering levels- the cost is relatively flat at lower engineering standards). Fuel costs only add 0.1% of the cost to a rocket launch, according to Elon Musk (the CEO of Space-X). The Microwave Thermal Rocketry cost of $6000/kg (vs. $10,000/kg for conventional rockets) accounts for the cost of Microwave Transmitters. It accounts for the cost of electricity generation. It accounts for ground facilities and operational costs. It's based on a total-costs estimate by experts that includes everything and the kitchen sink. Regards, Northstar

@OP IT is for precisely the reasons you described that I NEVER use the NCS adapter. Its mass is completely nuts. Not to mention that none of the adapters should be empty in the first place- they should all be capable of holding a moderate amount of fuel (adapters have slightly increased structural mass in real life compared to a cylindrical aerodynamic shell, but most are either hollow and *very* lightweight, or still contain some amount of fuel...) Regards, Northstar

Squad listens to the forums now and then, so it's not necessarily a bad idea to discuss things here, hoping they'll pay attention... Realistic aerodynamics ARE intuitive. Many KSP players come in with an accurate understanding of physics. Some even with pilot training or experience with flight-simulators. Whereas orbital dynamics are more esoteric, and fewer players accurately know what to expect (I was the rare exception to this- since I knew about how orbit actually works, and already had a basic grasp on the Rocket Equation I performed a gravity-turn and made orbit on my first successful launch...) a lot of players come in knowing what to expect when flying in the atmosphere. Thus, the current aerodynamics system is a pain in the a$$, and LESS intuitive to rookies than a realistic system. If the devs implement realistic rules about how airflow behaves, and the effects of Mach (speed), then ALL the other quirks of aerodynamics (from ballistic coefficients to types of instability) naturally flow from those rules. A sufficiently intelligent player should be able to reason their way through those- especially if the devs improve the tutorials available to new players to mention aerodynamics, maybe even provide some "Advanced Tutorials" that teach players actual principles of aerodynamic design in detail... Regards, Northstar

Patents Licensing is a very underpowered strategy, but your suggestions for Outsourced R&D are *DRASTICALLY* out of wack. Just using your own example, almost 20k funds is a HUGE amount of money to give up for less than 6 Science. The current strategy is actually close to reasonably balanced- it shouldn't be adjusted by much more than 50% down (250 Science for 20,000 funds is a fair deal.) Regards, Northstar

I agree a 3.75 meter crew pod would be nice (particularly for recovering crew from a doomed 3-man mission while still launching 3 fresh crew of your own). But there would need to be an even larger (5 or 6.25 meter) line of parts to go underneath it... Not that I have a problem with that- the Saturn V was 10 meters in diameter, and SLS has a 8.4 meter core (and SRB's strapped to the side of that!) But if we're going that big, the devs also need to reform the fuel system to be more realistic- the current stock combination of fuel density and ISP is impossible. The ISP for many engines is at about the level that would require Methane/LOX, but the fuel-density is similar to hypergolics (and like with hypergolics, there is no boil-off). Bigger rockets become capable of being safely built to increasingly tall heights (especially if the devs added a size 4 node to go with a larger size line) and have better ballistic coefficients (important when the devs reform the aerodynamics system), and can be cost-effectively staged to a larger degree: thus they can achieve greater payload fractions. So, what I'm saying is, for balance reasons the devs need to make the game harder in other ways if they add a 5+ meter line (just making 5 meter parts expensive wouldn't cut it- and with the fuel tanks would be especially unrealistic, as larger fuel tanks become CHEAPER per litre of fuel in real-life due to the Square-Cube Law... Larger fuel tanks have relatively less surface area, and *proportionally* thicker walls as they are pressure vessels, for the same overall mass ratios- but it's much cheaper to build a 1 cm thick wall to within 0.1% accuracy than a 200 mm wall...) Bringing fuel-density and ISP in line with real life (probably adding all the fuel mixtures below for advanced players to play around with- newbies could just stick with the defaults for an engine, and fuel tanks would be tweakable to different mixes and try to auto-default the correct mix for the engines attached...) and possibly adding boil-off (*GASP*) would make for a much more difficult/balanced experience if larger parts were added, and a much more realistic system when ISRU is implemented. With a toggle on boil-off under difficulty options, and electricity-hungry parts (active-cooling thermal fins) to allow players to mitigate it for longer missions, of course! By the way, for reference, here is a list of major real-life chemical-rocketry fuels in order of increasing ISP, decreasing fuel-density, and increasing boil-off (all 3 follow the *exact* same pattern/order) Hypergolics (MMH/UDMH/Aerozine + N2O4) [iSP rarely exceeds 340 seconds in vacuum, no boil-off] Kerosene + Liquid Oxygen [iSP rarely exceeds 360 seconds in vacuum, moderate boil-off of LOX component] Liquid Methane + Liquid Oxygen [iSP rarely exceeds 380 seconds in vacuum, moderate boil-off of *both* components] Liquid Hydrogen + Liquid Oxygen [iSP rarely exceeds 480 seconds in vacuum, HEAVY boiloff of LH2, moderate boil-off of LOX] It's also worth noting that Nuclear Thermal Rockets (such as NERVA) can use the following propellants instead (they can also use Meth/LOX or LH2/LOX, via an "afterburner" effect for improved thrust but reduced ISP- but never Kero/LOX or hypergolics...) listed, as before, by decreasing density: Liquid Ammonia [iSP around 420-480 seconds, NO SIGNIFICANT BOIL-OFF IN SPACE] Liquid Methane [iSP around 520-580 seconds, moderate boil-off] Liquid Hydrogen [iSP of 840-1000 seconds, HEAVY boil-off] It's worth noting that if Squad ever wanted to include a Microwave Thermal Rocket system (doubtful, but I really wish they would- as the technology is *just* around the corner in real life, and it would draw more attention/support to it), it would work off the same fuels as NERVA, with slightly lower ISP, but none of the heavy mass of an onboard reactor... (a Microwave Thermal Receiver would be much lighter than even a chemical rocket engine) Regards, Northstar

Honestly, the "Era" KSP takes place in is more your opinion than anything else. It would make just as much sense for KSP to be taking place in a modern developing nation that doesn't (yet) have an advanced space program as for it to be taking place in the 1960's-1980's. And, of course, it's about little green aliens, not humans- so there are no exact parallels. Honestly, I'm not a fan of any attempt to re-create the Apollo Era in KSP. I don't want to REPEAT history- I want to make it. I think KSP needs to look more to the cutting (bleeding) edge of modern rocketry and even to technologies that are *just around the corner* (like Microwave Beamed Power- PM me if you want to learn more, but it really is a technology that is only 10-20 years away, with a subscale demonstration planned by a NASA lab in 2018), rather than to the so-called "glorious past." It's human nature to romanticize the past, but honestly, I don't want to play it. Even Apollo wasn't all that popular in its era, with only just over half the US population supporting the program before the first Moon landing (and even less afterwards- when most people foolishly thought we had "won" the Space Race). I want to plan a Mars (Duna) mission, or a glorious mission to Jool/Jupiter, using some of the new technologies that make this possible, not putz around the Moon and low orbit for 30+ years... And I want to do it realistically/believably enough that I feel like I'm really envisioning/planning/executing missions that would be possible in real life. I *LOVED* it when Squad added the RAPIER engine (a reasonable analog of the real-life LH2/LOX SABRE engine, and I think there was even a more similar Kero/LOX "RAPIER" engine planned as well in real life...) I went bananas when they announced they will eventually include some form of ISRU (although it remains to be seen how realistic/believable/fun their system will be- personally I think it's easiest to create a fun system working off real ISRU systems, as it leaves you free to figure out other things than the chemistry- which is already known...) And I will be ecstatic if they follow through with their hints that they will finally start reforming the aerodynamics system to make it more realistic (they have, at least, indicated the current system will be going out the window). I *DON'T* want to see KSP become any more technologically primitive or unrealistic. The laptop is just one indication of a futuristic lean, which I like, in my opinion. Regards, Northstar

Welcome aboard JackDraak! We're glad to have you with us! Feel free to head over to the Tutorials section with any burning questions you've developed about KSP over all this time. Or pop into the Science Labs, and discuss real-life spaceflight, science, and rocketry... Regards, Northstar

Two words: Cycler Ships. The cost of reaching Mars goes DRASTICALLY down when you can re-use the same ship to get there over and over. And, when you have the massive fuel-savings of only needing to accelerate your habitat for the duration of the transfer to a Mars intercept once (a Cycler Ship takes the same Delta-V as a 5 month Mars transfer, and can be reached over the course of *years* with ion engines before you ever place a crew aboard the ship). And when that allows you to make repeated use of heavy equipment that saves on mass in the long run with enough use- like bioregenerative life support (aka. Greenhouses/Aeroponics), heavily-insulated actively-cooled Hydrogen tanks for the Cycler Ship (you still have to transfer the fuel back over to a more lightly insulated orbiter vehicle that will separate from the Cycler when you reach Mars, though), and an onboard comms-relay on the Cycler Ship so you don't have to orbit as heavy communication equipment around Mars... (as the outbound Cycler Ship won't get too far from Mars before the return Cycler starts closing in, this can reduce the maximum distance to the nearest comms relay...) I even started a thread specifically on Cycler Ships if you're interested: http://forum.kerbalspaceprogram.com/threads/102410-Cycler-Ships Regards, Northstar

Absolutely no boil-off is technically impossible, but it CAN be reduced to completely negligible levels. Like most thermodynamic processes, boil-off occurs MUCH more quickly at higher temperatures. The only reason boil-off is a real problem for rockets is because the fuels start to heat up from the moment they are placed in the tank. Insulating the fuel tanks can slow this process, but the only real way to STOP or even reverse the rise in temperature is to actively cool the fuel tanks. If you keep the fuel tanks cold enough, boil-off becomes a non-issue. Regards, Northstar

That's not the purpose of Microwave Transmitters. The Microwaves don't act as propellant, they act as an energy source. You can get a much better ISP (more than double) and TWR than with chemical rocketry- and you should know from playing KSP what that means... Hahaha, you made me chuckle. You DON'T use GW-class Microwave Transmitters to beam a few GW of power. That would be an *extremely* silly way of doing it. Instead, you use literally thousands of MW-class Microwave Transmitters, all of which focus on the same target. It's MUCH more cost-effective, and the array still works fine if a handful of transmitters fail (allowing year-round operation without down-time for maintenance, since you can individually power down and fix broken transmitters while everything else still works). MW-class transmitters are already available off-the-shelf at a reasonable price ($2 million/MW). Purchase 1000 of them (for approx. $2 billion, maybe less if you get a discount for buying in bulk) and you can launch 100+ 1-ton payload SSTO rockets (or 2-3 ton payload spaceplanes) a year for almost no marginal cost (electricity is, comparatively, dirt-cheap). It costs over $10 million to launch a metric ton of cargo to orbit using chemical rockets, by contrast. The official cost-estimate is that using disposable SSTO *rockets* (not reusables, or spaceplanes, which are even more cost-effective) you can get $6 million/ton to LEO. Additional cost-savings (via higher payload capacity per-MW, and thus reduced need for beamed power for the same payload demand) might be possible if you use the atmosphere for propulsion in the lower atmosphere (via microwave-powered Thermal Turbojets: which require ZERO internal fuel to operate) instead of relying solely on internal propellant stores. As the rocket/spaceplane climbs and the air becomes thinner, it would eventually switch over to thermal-rocket propulsion... (ideally through "Hybrid Thermal Turbojets" which would simply switch from external air to internal propellant, or even a design with a "conventional" LH2 + Intake Air stage in between) All of this (minus the Thermal Turbojet part) is the official plan for how to (theoretically) implement Microwave Beamed Power by NASA and Escape Dynamics, by the way. It's not just my own ideas talking. Regards, Northstar P.S. Thermal Turbojets/ Hybrid Thermal Turbojets are really just designs to take in gas and superheat it with a nuclear reactor or Microwave Receiver before spitting it out the rear end for thrust from thermal expansion. It's completely oblivious to whether it utilizes external atmosphere or internal propellant, and you could probably mix the two if you wanted when the air became too thin to run the TTJ purely off atmosphere. You could pass through a stage where there was combustion of the internal propellant with external air that would start to occur with a fuel mix- similar to in a conventional turbojet, but with a lot of added heat from the reactor/receiver... So, the *ideal* pattern would be: Intake Air only --> Intake Air + LH2 --> LH2-only or LH2 + LOX. Every one of these stages has been individually tested in either Thermal Turbojets tests back in the 1960's (Intake Air- only mode), SABRE jets (Intake Air + LH2), Thermal Rocket tests (LH2 only), or in conventional rockets (LH2 + LOX). The tricky part is integrating all these fuel-modes into a single engine, that operates with added heat from a reactor or Microwave Receiver...

Hey guys, So I figured out the bugs I was experiencing with Realfuels (turns out, I didn't install the .DLL when I updated ), and got back to playing. And without further adieu, I present my next vehicle... That's right! You're looking at a Spaceplane! I know I haven't exactly been the biggest fan of spaceplanes lately, since they take so much time to fine-tune the designs of and carry so little cargo; but I got a contract to test a Hydrolox-only Aerospike engine, and I couldn't resist the opportunity to design a spaceplane around it- the purpose for which the engine was clearly best-suited... Anyways, the ascent didn't exactly go smoothly (the spaceplane kept spinning out of control at around 26 km if it acquired even a small sideslip), but eventually I did manage (with lots of F5/F9) to get it to orbit... Then I deployed the payload: a small canister of hypergolic fuels destined for my Munar Orbital Science Station: I intend to launch an ion-powered tug soon to tow that to the Munar Orbital Science Station. My only remaining orbital tug is currently en-route to Minmus (where I will use it to retrieve the orbiting used science module and bring it to the Mun for cleaning. I'll probably also transfer over the fuel- after all, it is a fuel tanker. After that, I'm toying with using it as an interplanetary drive section or some other purpose- I haven't decided yet...) You'll note that there is only a docking port on one end of the cansiter- that's because the tug will be equipped with a "Klaw" so it can also move around asteroids and debris... (the tug will grab onto the flat end of the canister) Then came the most difficult part of the entire mission: re-entry... The first attempt didn't go a planned (the spaceplane was coming down too far from the KSC and I was having issues with keeping it stable), so I aborted the re-entry attempt and tried again later... The second time was the charm, and the spaceplane safely made it back to the KSC runway (although still with quite a few F5/F9 attempts...) Success was owed, in no small part, to FAR and pragmatic use of S-turns. You can see me performing a few in the album- where the spaceplane turns at an angle into the wind to increase drag and path-length towards the KSC... Anyways, spaceplanes are HARD. That's why I mostly stick to rockets... Regards, Northstar

Actually, a *proper* nuclear reactor (as opposed to, say, a Stirling Engine nuclear reactor or an RTG) has much higher power-density than any solar panel except thin-film panels (which can only be coated onto existing hard surfaces- such as the entire sun-facing side of a Cycler Ship...) Meaning, you get more electric power per kg of weight with the nukes. Of course the BEST option from a mass-efficiency standpoint is just to *beam* the power at the Cycler Ship via microwaves, and receive it with a rectenna (which is extremely lightweight). That same infrastructure is *also* really useful for launching rockets or spaceplanes from the surface of the Earth in the first place (using Microwave Thermal Rocketry), and could provide the kind of baseline power-demand on the Microwave Transmitters that would allow them to *quickly* pay for themselves without having to launch 100+ rockets a year... (and at times where there are no active Mars missions, those same Microwave Transmitters could be utilized to launch rockets/spaceplanes from Earth...) Regards, Northstar P.S. Microwave Transmitters are *already* economically viable for rocket and spaceplane-launches without needing to power a Cycler Ship. The ISS consumes up to 80 metric tons in consumables (includes life-support, fresh clothes, etc.) a year- so that demand alone is capable of supporting a 1000 MW array of Microwave Transmitters (which could launch 1 metric ton of payload to LEO per launch using rockets, or significantly heavier payloads using spaceplanes- would cost about $2 billion if transmitter costs remained fixed at $2 million/MW-capacity, and would last about 10 years before starting to wear out... Current launch costs are about $10,000/kg, so the system would need to launch at least 20 rockets/year to pay for itself...) P.P.S. Just IMAGINE what electric thrusters could do with 1 GW of electric power, and only the weight of a small rectenna (1 GW is enough to power a Dual-Stage 4-Grid Ion Thruster with a thrust of 10 kN and ISP of 19,300 seconds, to give a rather absurd example... And with electric thrusters, the lower your ISP, the higher your thrust.) Now you're starting to see why Microwave Electric is the highest-performance option for a Cycler Ship...

You mirrored my thoughts exactly. Except, embarrassingly, I didn't think of the zero-boiloff tanks for cryogenic fuels (such as Liquid Hydrogen) part. Boil-off of cryogenic fuels is one of the BIGGEST problems facing Mars mission plans today. A rocket using LH2/LOX has to carry extremely heavy insulation and active cooling equipment to keep its fuel from boiling off. If you use Kerosene/LOX instead, you have problems withe the Kerosene coking onto the engines with repeated engine use. If you use hypergolics, there are issues with toxicity and low ISP. Methane/LOX is probably the best option, but there are no space-grade engines designed specifically to burn that mixture yet... (a couple are in development, and several have been retro-fitted to work with Methane, though) Carrying the heavy insulation and cooling equipment on the Cycler Ship lets you use LH2/LOX (Hydrolox) without needing nearly as much insulation (and no cooling equipment) on the vessels that will actually be having to make a capture-burn at Mars. It also lets you use Hydrolox on the lander- although you might be better off using a Methane/LOX engine there for a more compact form, and the greater ease of refueling the Methane via ISRU (you *can* find Hydrogen on Mars- but you're going to have to dig down and melt water-ice in the soil to get it), unless you can design a dual-use engine that can burn both Meth/LOX and Hydrolox on a single mission. Hydrogen can also be used as feedstock for the Sabatier Reaction and ISRU on Mars... Finally, if you switch to Microwave Thermal Rocketry, pure Hydrogen is the highest-ISP propellant for that (and is even harder to store than Hydrolox- as Oxygen is far less cryogenic than Hydrogen). If you carry a nuclear reactor on the Cycler Ship and beam the power to the Mars capture vehicle and lander (or even just emplace a Microwave Relay on the Cycler to re-focus microwaves beamed from Earth), then having access to Hydrogen without needing heavy insulation on the capture vehicle and lander is a great boon for efficiency... So, having the ability to carry Hydrogen out to Mars without having to accelerate heavy insulation and cooling equipment there over and over is a HUGE advantage of using a Cycler Ship... (which probably already has impressive electricity-generation capabilities anyways: to power electric thrusters and life-support) Regards, Northstar

I'm sure you saw my post on the RealFuels thread, but I just wanted to make sure you knew- I solved my bugs. It turned out the issue was that I didn't have the RealFuels .DLL installed. Not sure why that affected some fuel tanks, but not others, though. The ones that were worst bugged seemed to be the ones that were updated most recently- so maybe it was a difference in the way they were coded that made them more dependent on the DLL to hold the correct fuels... Now I'm just trying to get the Thermal Strake part Rabada sent me working properly (I re-balanced it myself and fixed a few odds-and-ends wrong with it, but couldn't get it to work as a heat pump...) And ZZZ should also be sending me a Thermal Fin part soon enough (this one with BLACK color and a triangular shape- so basically better than the one Rabada sent that re-uses a white-colored, long rectangular Novapunch Strake part...) that I will need to get working as well/instead... Oh well, idle hands do the Kraken's work. Regards, Northstar

Oh. I didn't think to try Action Groups... It was on a newly-designed craft using the .DLL that was posted before (*not* the 8.2 release .DLL, but the 8.2 pre-release) in response to my bugs due to not having the .DLL at all, the other files that were posted on Github as of December 9th, and with the R&D entry for the part freshly-purchased (the Thermal Strake, unlike the Thermal Fin, has an entry cost to make it more balanced). So then I have no idea what might be causing the Strake not to work, if it is neither of these things. I suggest going and downloading the Strake yourself (I posted a Dropbox link to it here a couple posts ago) and seeing if you can figure out how to get it working, or seeing if it works for you... Regards, Northstar

I didn't forget- but it still only takes two trips to break even. The fuel-savings from using a more than 40x more efficient engine (19300 s vs 480 s) more than pay for the tiny cost of fuel of accelerating the "tender" ships. The size of the Cycler ship would easily dwarf the "tender" ships, so it only takes 2 missions to break even. (to be precise, I think the cycler has to be about 3x as massive as the "tender" ship in order for the break-even point to be 2 missions or less) Cyclers are actually great for exploratory missions as well. The single greatest strength of a Cycler Ship is that you can accelerate it to its cycle orbit with low-thrust, high-ISP electric engines (or solar sails) over the course of *several* years. There's no need to get to the cycle orbit quickly, because there are no crew onboard yet during the initial acceleration to the cycle orbit. This advantage holds just as well for a pair of just two exploratory missions as it does for regularly-scheduled "shuttle" service between planets (and in fact is MORE advantageous for exploratory missions, as by the time you have regularly-scheduled "shuttle" service you should have the capability to refuel craft in Mars orbit, and send them off from Earth with things like magnetic tethers...) Regards, Northstar

The break-even point for a pair of full cyclers (ones that can operate perpetually- unlike semi cyclers, which are more comparable to free return trajectories) is at just 2 manned missions. Each cycler takes about 50% more Delta-V to launch than placing the same mass on a Mars Hohmann trajectory. However neither has to make the return-burn to Earth/Mars (you place the cyclers so that one has the short leg of its cycle Earth --> Mars and the other Mars --> Earth), meaning it actually costs less Delta-V to place a single Cycler on a cycle trajectory than it does to accelerate the same mass of habitat/radiation-shielding/life-support systems to Mars, capture it there (mostly by propulsion- aerocapture is extremely difficult, although you might still set a periapsis through the edge of the atmosphere to maximize the Oberth Effect...), return it to Earth, and let it burn up in Earth's atmosphere... Since you need two cyclers for the system to work, and a single cycler is still going to take more than 50% of the propellant of a Mars round-trip on a conventional transfer vehicle, you need to perform at least 2 manned missions for the cycler to pay for itself. A cycler will basically always pay for itself after 2 cycles. You can either use it for 2 manned missions (and launch it with crew onboard and chemical engines), or launch it unmanned and spend the first cycle and several years just slowly achieving the cycle orbit with ion engines and solar sails... (it costs less mass to launch 2 cycler ships on cycle trajectories using engines with ISP over 19,000 seconds like the Dual Stage 4 Grid ion thruster being worked on in real life, than it does to launch a single transfer+return vessel on a round-trip with chemical engines that can max around 480 seconds on the outbound trip with LH2/O2 and only around 380 seconds on the return trip if you use Mars-derived Methane/LOX, so great are the propellant-costs) Regards, Northstar P.S. To launch a cycler with electric engines, you would probably want to power them with Microwave Beamed Power, as that is BY FAR the lightest way to get the necessary power to them. A nuclear reactor or solar panels will be MUCH heavier. You will also need to use a huge cluster of ion engines (probably over 20 engines) if you can't develop a multi-MW thruster with better ISP than VASIMR... (which CAN scale up to multiple MW)

You're right- there's now a toggle on the right-click menu for the original Thermal Fin part and the ZZZ radiator (there wasn't before- maybe it was bugged), and they now work great. However, for whatever reason, those parts still don't show up in Career Mode (only in Sandbox), and there is still nothing visible on the Thermal Strake- and it doesn't yet work at all. The only difference I can possibly find between the Thermal Strake and the other heat pumps is the node/surface attachment rules (I assume the heat pump module needs to recognize the fuel tan the radiator is attached to- maybe there's something wrong about how the Thermal Strake attachment rules are set up???) Other than that, it's got the same heat pump module included (but not "animation" module), so I can't figure out why it can't be toggled on/off... Regards, Northstar

Turned on? What do you mean by that? I'm not aware of any on/off switches I saw anywhere for the heat pump module... If you mean the ZZZ radiator (which still doesn't even normally show up in parts catalog in Career mode) has to be deployed- that's great, but the other heat pump parts aren't deployable. Nor can they be turned on/off by right-clicking in my save... The heat pump module code is *exactly* the same for the original Thermal Fin, the Thermal Strake, and the ZZZ radiator (except for the transfer rate, which is higher for the Strake due to its higher mass/ surface area). So I can confirm that's not the reason none are working for me yet... Regards, Northstar

Do you think you might be able to figure out how to get the heat pump parts working again? (including the Thermal Strake I just submitted) Currently, none of them do anything (not even the original Thermal Fin part)- they don't even consume electricity... EDIT: It also just occurred to me that the original Thermal Fin part needs stock aerodynamic coding (the Thermal Strake already has it) if it's going to be kept in the mod. I'm just so used to playing with FAR that I didn't think of it (FAR imposes its own aerodynamic code on ALL parts- even ones without normal physics significance- through the body lift code if nothing else if it doesn't have proper FAR wing code already included...) It's shaped like a square wing part, so it SHOULD interact with the atmosphere like one (meaning it experiences different amounts of drag depending on orientation, for instance). I suggest comparing it to the existing wing-board parts to get an idea of what the correct lift rating should be. Maybe you could add stock aerodynamic code in while you're looking into getting the heat pump parts working properly, and doing that thing you mentioned regarding animations? Regards, Northstar

Shoot- I have terrible timing! Launchpad tests of the Thermal Strake reveal it doesn't do anything yet (not even consume ElectricCharge). But then again, neither does the existing Thermal Fin at the moment, from what I've heard- and it uses exactly the same heat exchange module as the earlier Thermal Fin. HOWEVER, I did need to correct a few odds+end in order to make sure the heat pump code was entered correctly. I also updated the part description and name since I first posted the link. So, the part.cfg is now a bit different than when I posted it less than an hour ago. Here's the updated file: https://www.dropbox.com/sh/7v29geiqf8x1d1m/AADewSgV7v0Zo7PLVq1H0SAJa?dl=0 Please use this version, rather than the earlier version. At the very least, even if I didn't manage to get the heat pump working correctly (I ensured the code is that same as the existing Thermal Fin though- so it doesn't work for exactly the same reasons), I at least managed to update the description and part name, so players know it's a thermal fin and not just an aerodynamic protuberance. Regards, Northstar