Northstar1989

I hope not with Thermal Turbojets- this is one of the few parts that realistically wouldn't have all its mass concentrated at the rear of the plane... Hybrid Turbojets do present a problem though- Thermal Rockets should have very high distance-losses to efficiency, if they accept ThermalPower over a distance at all- but Thermal Turbojets shouldn't have any problem with being built into the length of a plane without suffering much if any distance-losses, as it's the airflow and compressor that are built forward (a compressor is far heavier than just an air-intake, and is the biggest source of weight in jet engines), not the heat-exchangers... (probably only on the order of 1-2% total losses should occur for most Thermal Turbojet using designs under 20 meters in length) Regards, Northstar

Hi guys, so I decided it was about time to stop wasting my time debating rocket science (and racking up infractions) in the Science Labs, and put as many of my ideas into practice as possible in a semi-realistic Mission Reports playthrough- occasionally putting my knack for storytelling into action in the process. This is Kerbal, so don't expect full realism or seriousness- but some of the general ideas still hold, and I am playing with a large assortment of realism-mods... The Premise: Kerbal-kind had abandoned manned space exploration beyond Low Earth Orbit after a series of manned Mun missions (sound familiar?) for more than 40 years of mucking around with space stations and ground-science, and after a period of time let go of the capabilities to do even that. Knowledge and capabilities in rocketry slowly decayed since that time, but Kerbal ground-based physics, chemistry, and astronomy continued to advance... Finally, after more than 70 years since traveling to the Mun for the first time (yeah, this is supposed to be set a bit in the future) Kerbals have decided, under the leadership of a charismatic politician- Northstar Kerman- to return to space. Some critics level charges of it being a waste of resources better spent on "other pursuits" at the renewed space program- but this has only energized engineers to seek ways to save on costs through new technology and reusability... Plans have already been drawn up for In Situ Resource Utilization (including Propulsive Fluid Accumulators) to be made use of wherever possible to save on long-term costs and the chemistry has been extensively validated on the ground, Microwave Beamed Power is undergoing intensive finalizing research and development and is hoped will be available within 2 years, primitive Mass Drivers are currently undergoing extensive testing for a highly-reusable alternative to Solid Rocket Boosters for the initial boost off the Launchpad, and some engineers even whisper of something called a "Cycler Ship" as cheaper way to get Kerbals to Duna with plenty of onboard living-space available... Although much knowledge has been lost (current capabilities barely exceed 1970's standards, aka. rocket tech level 5 in RealFuels+Stockalike) it is hoped that by the end of the decade Kerbals will have set foot on Duna and by paving the way for a brilliant new sustainable future in space. Here is an except from Northstar Kerman's groundbreaking speech: "In the words of one of my great predecessors, we strive to do these things not because they are easy, but because they are hard. We must push forth, cross new expanses and explore new lands not because of today, but because of the future. If we do these things, our children's children's children's children will look to the stars some day, and see not Duna in the night-sky but Kerbin. They will remember these days as being when Kerbal-kind first set forth and explored new worlds on their own feet. When adolescents were inspired to become engineers, and adults were inspired to become writers and poets dreaming of the stars. We will leave a legacy for future generations not of cowardice, but of bravery. Not of stagnation, but of progress. In my training as a biologist, I learned one thing- grow or die. That is the way of life. That must be the way of our species. By consigning our fates to this small planet we sign our death-warrants. By reaching for the stars, we birth our future. Here are screenshots of the first set of launches, of Munar-1: the first attempted Kerbal Mun-landing in more than 70 years. Wanting to set a bold example, Gene Kerman (the new administrator of the KSC) has decided to place not two but FOUR Kerbals on the Munar surface for this initial landing... The first launch consisted of a science-package for the Mun Lander and a refueler. Due to limitations of the Vehicle Assembly Building construction-capabilities and the launchpad (30 parts, 36 meters of height, and 140 tons of dry-mass), a rocket that could lift both the necessary scientific equipment and fuel for the 5-Kerbal lander, as well as the lander itself, was deemed impossible until improvements to the facilities could be made. Instead, to save on costs and work withing existing limitations, a series of rocket pushing the very limits of these facilities (and making use of on-launchpad refueling to increase the maximum rocket weight beyond what could be moved to the launchpad by the crawler) were designed. Each, highly-similar to the last, but with slight but significant modifications- for instance replacing one off-the-shelf rocket engine-cluster (R&D purchases are enabled in this save, but the engines ultimately selected were already purchased for earlier missions) with another more powerful upper-stage engine for the first launch, or attaching 3 radial boosters to the sustainer-stage of the Command/Service Module (which was the heaviest payload of the 3 launches) This is not a game-bug with the recovery of the Lander Launch Vehicle's sustainer-stage. The crash-tolerance of the engine was 60 m/s, whereas its terminal-velocity was only 54 m/s. Engineers remained uncertain as to whether the empty balloon-tanks could manage to survive this impact- until somebody pointed out that they no longer had the mass of a 20+ metric-ton fully-fueled 5-man Mun lander or more than 70 tons of upper-stage hypergolic rocket fuels onboard to support, and that the g-forces experienced by the lithobraking would thus be well within their capabilities. Minor repairs to the equipment were still deemed necessary afterwards... (OOC: Consider these repairs part of the cost-recovery factor, which honestly is excessively low for just loading an empty rocket stage onto a barge and shipping it across the ocean... IIRC real-life Sea Dragon launch-stage was, not coincidentally, designed for splashdown and recovery at exactly the same Terminal Velocity of 54 m/s... In some ways, splashdown is actually harder on the equipment when you have a vertical touchdown trajectory, as the pressure on the sides of the rocket becomes comparatively large due to fluid pressure- this horizontal pressure is actually why the Falcon 9 launch-stage that ruptured after splashdown in real life did so, not because of the vertical component of the forces of the soft-landing...) The Lander and the Command/Service Module docked and rendezvoused in orbit before proceeding to the Mun together. Unfortunately, I missed out on taking screenshots of some of the rather spectacular scenes that resulted from the docking+transfer due to not deciding to start this Mission Report until after I realized I still really wanted to do one of these a day later. Rest-assured though, I'll try and grab at least a few more screenshots along the way (I won't be taking screenshots *quite* as obsessively as in some of my previous Mission Reports, where reporting became a chore, however- so don't be disappointed if you only see fragmentary records of the key moments of missions for long stretches at a time...) Regards, Northstar

Yup- I've done that before. In fact, see the recovery of my sustainer-stage in my latest pictures: the stage simply lands on its engine as its Terminal Velocity (54 m/s) was lower than the engine's impact tolerance (60 m/s). I actually found that one out by accident- I thought I would be watching my sustainer burn up in the atmosphere with Dealy-ReEntry (nope, the angle was so shallow that re-entry heating never got high enough to be a real problem), the thing land on its side and explode (turns out engine-first was the most stable aerodynamic profile with no fuel left), or a glorious explosive crash-landing/explosion into the ground- not a free recovery of one of my stages. It can be done in real life too- the Terminal Velocity of the launch-stage of the Sea Dragon was only supposed to be about 54 m/s with a drag-skirt around the top (sort of like a very weak parachute) and it was projected to be able to survive splashdown in the ocean at up to 60 m/s (it was a pressure-fed Kero/LOX stage built to Big Dumb Booster levels of precision to save on costs- so no major issues were expected with getting saltwater inside the engine...)

Since I went through all the effort of taking these screenshots (which I also sent to the wonderful team of the Kerbal Podcast- I hope they'll share them on their website next week if they discuss them at all) I thought I'd also share them with you guys... These are the launches of my 3-part Munar-1 mission: my first mission to the Mun in my current Career game in Real Solar System 6.4x (I had a save-breaking error before that forced me to lose my last save, so I started off with a lot of free Science using the Custom difficulty setting, nor wanting to grind back up the tech tree...) The first launch was my Scientific Package (launched separately due to the 30-part limit on the level-1 VAB) and refueler for the lander (most of its initial fuel-load is used for the Munar transfer). The second was my Munar lander (two-stage, and launched ahead of the Command/Service Module due to its minimal use of cryogenic fuels- I am also playing with RealFuels installed) The third launch was my Command/Service Module (which was launched last due to its heavy reliance on HydroLox propulsion, so as to minimize boil-off) The Lander and Command/Service Module rendezvoused+docked in Low Kerbin Orbit before heading off the the Mun together (this allowed the lander to use its lower-ISP hypergolic engine for the initial part of the transfer-burn, whereas the Command/Service Module finished the burn with its HydroLOX engine- mainly on the next peripasis-kick around Kerbin...) I wish I had taken some screenshots of that as well, because it made for some rather spectacular imagery of their docking and making their two-part transfer-burn to Munar intercept... (where the CSM will perform the capture with its HydroLOX engine) Regards, Northstar P.S. For those wondering, using your lower ISP-fuels first is a way to minimize propellant requirements for any mission. This also works in stock KSP: for instance using chemical rockets before ion engines, or a lower-ISP chemical stage before one based on LV-N engines... Docking my Lander and CSM together allowed me to thus save some of the Lander's fuel (and reduce the size of the refueling-tanker), even though the Lander had enough fuel to get to the Mun on its own: as I was able to use the lower-ISP hypergolics for the initial part of the Munar transfer, and HydroLOX propulsion for the remainder (due to the relatively much higher mass of the CSM, the Lander was not able to complete the transfer-burn on its own with the Command/Service Module attached...)

KSP-Interstellar (in all its iterations) uses the IntakeAtm resource for Thermal Turbojets- which work in atmospheres without oxygen (because no combustion is involved in the propulsion system: Thermal Turbojets only require a heat-source in the form of a nuclear reactor or microwave receiver and an atmosphere of any possible composition...) This is important to propulsion on places like Duna and Eve- in fact I've designed SSTO craft for Eve that use Nuclear Thermal Turbojets for launch-stages (and Nuclear Thermal Rocket propulsion to reach orbit) before, and actually have flown Nuclear Thermal Turbojet aircraft on Duna as part of the Flying Duna challenge... It's important that IntakeAtm be maintained as a separate resource from IntakeAir because it can be found in places IntakAir can't (specifically, Eve, Duna, Jool, and some of the mod-introduced moons with atmospheres). Without it, we have no way to make Thermal Turbojets work on these planets where normal jet engines shouldn't- it was introduced as a separate resource as a matter of necessity, and the need for it has not grown any less with time. Regards, Northstar

It's only the density I'm concerned about. And while the final say goes to FreeThinker, I think as one of the co-creators of the KSP-I Extension Config (who has contributed large amounts of research and significant amounts of code to the project, and been there since rather early in its development) I can safely speak for him when I say it's a concern for the mod whether we use 1200 kg/m3, which is the current density in KSP-I Extended, or 770 kg/m3, which is the density currently found in the working-document. Also, RealFuels doesn't use LiquidCO2 at all (now to be LqdCO2- I don't think such a small name-change is really much of a sacrifice for consistency for anyone here...) it's a resource purely used by KSP-Interstellar Extension Config (it's not even found in base KSP-I as created by Fractal_UK, who is absent) for Thermal and Electric rockets... Regards, Northstar

RIP Nemoy. He touched us all. Maybe the devs could memorialize him with some kind of Easter Egg... Regards, Northstar

Also, the density of LiquidCO2 in the working document is currently listed as 770 kg/m3. The density used by KSP-Interstellar is currently 1200 kg/m3, based on real-world density data (a bit denser than LOX, which it should be, considering its 37.5% higher Molecular Weight...) Regards, Northstar

Aren't we going with 1 unit/Liter anyways, or did I miss something here? That seemed to be the general weight of opinion before... KSP-I uses LiquidCO2 at 1 unit/Liter with realistic density. Isn't this the density the CRP definition of LiquidCO2 should be based on? If so, I don't foresee any problem with KSP-I using LiquidCO2, but rather it seems it's Biomass (which, does that mod still essentially generate reaction mass out of nothing?) which would have the problem... Regards, Northstar

KSP-I Hydrogen Peroxide and RealFuels HTP are indeed the same thing. In fact, the RealFuels/KSP-Interstellar integration config (that used to be part of RealFuels until recently- when NathanKell removed it, stating that the development cycle of KSP-I Extended was too fast for him to keep up with) renames/replaces KSP-I Hydrogen Peroxide with HTP altogether. Regards, Northstar

He's assuming the molten salt is getting pumped to the Thermal Turbojet over a distance. Which honestly, I'm not completely sure about being a realistic explanation for this (I mean, you *could* do it, but I'm not sure I'd want to fly in a plane that was blithely pumping highly radioactive sale right past my cockpit...) However, there is a much better and more realistic explanation- real inline jet engines (including Thermal Turbojets) are never built with all their mass entirely at the rear like in KSP. Rather, they're built with the mass distributed out over the length of the vessel... So, it's entirely realistic to have the Thermal Turbojet's mass distributed over the length of the vessel (with most of this mass represented by the reactor, including things like the compressor and heat exchanger- the actual Thermal Turbojet nozzle is relatively light...), which is the effect allowing reactors to be located one part forward actually accomplishes... FreeThinker, I didn't know this was actually possible in KSP-Interstellar (reactor detection over distance). I know you originally implemented this as an idea for making Molten Salt Reactors more useful, but I would encourage you with Thermal Turbojets at least (I don't know about with Thermal Rockets) to allow reactor-detection over a single intervening part for ALL reactors. This should allow a more realistic mass-distribution for our Thermal Turbojet powered planes, regardless of the reactor type used... As for buffing up the Molten Salt Reactors, I would suggest implementing the ability to use them as a sort of garbage-disposal for nuclear waste that I suggested before by PM. A recap: Molten Salt Reactors would gain the ability to burn Actinides and other nuclear wastes in exchange for a somewhat reduced ThermalPower production while in this fuel-mode (the same way as using Thorium leads to an *increase* in ThermalPower production). This isn't exactly a new idea/feature for nuclear reactor even in real life- not only is it suggested/planned for some Molten Salt Reactors, it is already a feature of existing operational CANDU Heavy Water Reactors, with a development-timeline dating back to 1994... http://www.candu.com/site/media/Parent/NEI%20article%20Jan%202014pdf.pdf http://www.nuclearfaq.ca/brat_fuel.htm http://www.ccnr.org/advanced_fuel_cycles.html Regards, Northstar P.S. I'd just like to give my thanks to the forum poster who first directed me towards CANDU Reactors many months ago. It sparked my interest in reactors that could actually burn (rather than simply reprocess) nuclear waste- thus both greatly simplifying the nuclear waste problem and simultaneously alleviating problems with the limited worldwide Uranium supply only being projected to last for about 35 more years at current demand and growth until very recently (new supplies were discovered in the past few years that extended out this estimate a bit further into the future...) This was what ultimately led me to learning that Molten Salt Reactors share this capability with Heavy Water Reactors already in use- the ability to run on spent nuclear fuel. If you're reading this, hopefully you know who you are (although I will go and try to dig up that poster's name later...)

Also, FreeThinker, just to double-check, you're going to include the code for fixing the ISRU refineries to have cryogenic RealFuels modular tanks when RealFuels is installed in one of the next updates, right? You said you'd include it in 0.8 a while ago- but since you've released several more 0.7.x updates, and I'm starting to wonder whether maybe you forgot about it after NathanKell decided he was going to pull the KSP-Interstellar tank and resource-name fixes from RealFuels as KSP-I Extended has a much more rapid development cycle... Here the code is again, with a comment I've been including when using it in my current save such as to make the code easier to find/identify (if the fix isn't already in the next update, I suggest including the comment to make it easier for other to identify the purpose of the code in the future...) //Make ISRU refinery tanks insulated and modular @PART[FNRefinery]:FOR[RealFuels] { MODULE { name = ModuleFuelTanks volume = 1750 type = Cryogenic } } @PART[FNInlineRefinery]:FOR[RealFuels] { MODULE { name = ModuleFuelTanks volume = 1750 type = Cryogenic } } @PART[FNInlineRefineryLarge]:FOR[RealFuels] { MODULE { name = ModuleFuelTanks volume = 11000 type = Cryogenic } } Regards, Northstar

+1 REP for that succinct, but accurate answer (I'm particularly grateful since my being in the moderation queue means I can't answers questions like this quickly). At the kind of ISP-increases you're talking about, the plasma core reactors will use less propellant to move payload around, despite the much higher reactor/engine mass. What they will consume more of is antimatter- which is as you noted in very limited supply. I like the idea of having two different classes of antimatter reactor (I wouldn't go all the way to three- we're already suffering part-bloat), but I'm not sure I like the idea of limiting the size-range of each. Especially given that all rockets in KSP-I are much smaller than in real life, and some players (such as myself) play with Real Solar System- where using TweakScale, Procedural Fairings (especially for the Thrust Plates), and ProceduralParts to get bigger rockets is often desirable... Also, that reminds me- FreeThinker, the cost-scaling of the reactors using TweakScale is currently very off. In respecting Fractal_UK's original balance, and realism, the larger reactors should be much cheaper/Megawatt than the smaller ones. For instance the 1.25 meter particle bed reactor costs 15K, whereas the 2.5 meter reactor only costs 45K (but produces much more than 3x the power). In TweakScale, like in real life nuclear engineering (where miniaturization is often expensive, and larger reactors are more cost-effective), we need to respect this same balance- the larger reactors should not have cost that scales at the same rate as their size or ThermalPower. Regards, Northstar

Just from a mission-planning perspective, higher Thrust means shorter burn-times. This means that lower-ISP rockets actually will consume less antimatter (but more propellant)- so you have it completely backwards as to which is preferable given the limited availability of antimatter. Regards, Northstar

Like was discussed, intermediaries may have different uses (pressurized "Nitrogen" gas can be used for RCS in RealFuels, KSP-I Extended "Liquid Nitrogen" can't and shouldn't be able to, for instance), or the conversion may take significant amounts of energy (liquifying Oxygen, for instance, is not something you're going to want to do for a life-support system on a surface base due to the high energy-cost of liquification...) Regards, Northstar

Was able to *partially* reproduce your results GreeningGalaxy: 145.4 kN of Thrust at 191.7 seconds ISP and 138 MW of ThermalPower! It looks like there is an issue with how Thrust is being calculated with the Thermal Turbojets with reactors that can very their ThermalPower based on WasteHeat accumulation (namely the Particle Bed and Dusty Plasma reactors). With WasteHeat= 0 these reactors still produce the same excessively-low Thrust/MW levels I was observing before... Or rather, the issue seems to be that these reactors are not actually dropping their ThermalPower production when WasteHeat accumulates to levels as low as displayed... The Thermal Turbojet I tested above got roughly the same Thrust as my plane from before, which was operating at 0 WasteHeat and thus had over 849 MW of ThermalPower available: 145.4 kN of Thrust at 190-ish seconds is reasonable for a 850 MW reactor (in fact, it's too low- hence why I stated a 47% increase to the Thrust modifier for Thermal Turbojets is in order), but is *NOT* reasonable for a 138 MW reactor. FreeThinker, it seems we have a bit of a bug with the displayed ThermalPower levels not actually matching what is going on under-the-hood with some reactors. This needs to be sorted out before we can get any reliable data on what is actually going on with the Thermal Turbojets... OK, one more thing. GreeningGalaxy, I examined your one screenshot a little more closely, trying to figure out why your Thrust/MW is so far out-of-line with anything I'm getting, and I think I might have an idea (although, once again, you really, really, really need to post a lot more screenshots to confirm there is even an issue. At the very least, you should show the reactor's context menu in one screenie and the Thrust/ISP of the ThermalTurbojet in the very next one...) You are using a "Hybrid Turbojet" whereas I am using a standard "Thermal Turbojet". The Hybrid Turbojet is supposed to be an upgrade of the Thermal Turbojet that can also operate in rocket-mode, but Fractal_UK may have also given it a higher Thrust/MW than the basic Thermal Turbojet at the same ISP. If that should be the case, then *BOTH* our results are correct- the Thermal Turbojet really does under-perform real life Thermal Rockets like the NERVA (and needs a 47% increase to its Thrust) and the Hybrid Turbojet really is so efficient it's essentially pulling power out of nowhere... In that case, what needs to be done is the two parts need to be buffed/nerfed until they have more realistic performance. There's no reason the Thermal Turbojet should produce so little Thrust/MW, but there's also no justification for a Hybrid Turbojet pulling Thrust out of thin air... If the Thrust/MW turns out to be the same for the standard and Hybrid Thermal Turbojets (I'm going to test now to see if this is the case), then I don't know what to tell you- your data simply doesn't match anything I'm getting, and as a mod-developer I'm more inclined to go with my own data if no one else can reproduce your results... Regards, Northstar

The effects of atmospheric density are only due to how that effects the internal airspeed and temperature within the jet engine. With a precooler (a part that is available in KSP-Interstellar) these effects become *much* less significant up until you reach much higher compression factors... Viewed from a scientific perspective, there is no difference between a jet engine and a rocket (which is actually technically a sub-class of jet engine) except the internal airspeeds and temperatures. There is nothing magical about flying at high altitude that automatically makes a jet engine less productive- if you cool the intake airflow to the same speeds+temepratures as at lower altitude, the performance will actually be *better* (due to reduced atmospheric compression of the exhaust-stream, although a very minor effect with the high Exhaust Pressure of most jet engines...) Regards, Northstar Your numbers are way off for the power of reactors. The reactor that Thermal Turbojet is attached to produces over 800 MW of ThermalPower. Are you running the latest version of KSP-Interstellar Extension Config? The fission reactors received a MAJOR buff to their ThermalPower production to bring them in line with real-world values for reactors of that size/volume (based on data from Timberwind, SNTP, NERVA, etc.) Fission Fragment Rockets don't heat propellant- they expel the ChargedParticles (which are at temperatures of millions of degrees before hitting any other atoms/molecules) directly. Regards, Northstar - - - Updated - - - Also, the equation you're referring to is: Power = 1/2 * Thrust * Exhaust Velocity it is originally derived from the following equations: E = 1/2 m * v2 Thrust = Mass Flow Rate * Exhaust Velocity Notice the division by 2? Your calculations are all off because you forget to divide by 2. The Thermal Turbojet (connected to an antimatter reactor, I assume, based off the ISP?) is not getting more than 100% conversion efficiency. The ThermalPower of the reactor would back-calculate to 3 GW based on the proper implementation of the equation (in which you must divide by 2). Regards, Northstar GreeningGalaxy, as I point out in my other post, your math is incorrect. You forgot to divide by a factor of two- so you overestimate the Thrust Power of the engines you look at. Regarding the behavior of thermal engines, they are governed by a simple conversion of thermal energy into Thrust via "E = 1/2 m v2", which is the equation that has been at the base of our mass all along. After correcting for some inefficiency in the conversion, you get the performance we currently have for our thermal engines. I respectfully suggest you look at how I went about calculating the expected behavior of the thermal engines (it is well documented earlier in this thread and in the KSP-I 0.90 port maintenance thread) instead of assuming I made a mistake in my calculations. Regards, Northstar

OK, so in-flight tests proved invaluable... First of all, here the Thermal Turbojet is at low altitude: And here it is at optimal altitude (after this height, the TTJ started to lose Thrust and ISP...) Thrust *DID* increase with ISP, and fuel-flow remained fixed, as I expected/hoped- but ISP did not climb *nearly* as high as I was expecting... At about optimal altitude (which was higher than I expected), less than 20% of Thrust was being lost to velocity at this altitude (at 400 m/s 20% of Thrust is lost to the velocity-curve). I estimate the correction-factor for airspeed as about 1.2 (corresponding to 1/6th Thrust-loss). Thus, optimal Thermal Turbojet performance is approximately: ISP: 195.5 seconds * 1.2 = 234.6 seconds Thrust: 136.0 kN * 1.2 = 163.2 kN What was the EXPECTED result based on the sea-level performance? (note the correction-factor for 1/3rd throttle) ISP: 134 * 3.125 = 418.75 seconds Thrust: 320.4 kN * 3.125 / 3 = 333.75 kN And finally, most importantly, what would be the REALISTIC Thrust based on the optimal ISP of 234.6 seconds? Realistic Thrust at 234.6 seconds: (850/234.6) * 0.3 kn/MW * (849.8416 / 3) MW = 307.91 kN It appears that the way the velocity and altitude-curves are currently being implemented, the Thermal Turbojets are actually currently under-performing real life... Thrust/MW is only (163.2 / 307.91) * 100 = 53% of what we would expect based on the 0.3 kN/MW performance of the NERVA engine in real life... Thus, a 47% increase in Thrust/MW appears to be in order... Final Conclusions: Flight-testing reveals that only a 47% increase in the Thrust/MW of the Thermal Turbojet is in order... Regards, Northstar

Yes, but for reasons that don't affect our Thermal Turbojets. The main reasons the stock jets are OP'd compared to real life are as follows: (1) There is a MAJOR issue in the way their ISP is calculated. In real life, chemical jet ISP is calculated based on the consumption of liquid fuel (Kerosene, Hydrogen, etc.) not based on the total airflow/ exhaust-velocity. That means if a Turbojet has an ISP of 2500, but only 1/10th of its mass-flow is in liquid fuel, its actual Exhaust Velocity corresponds to an ISP of 250 seconds, not 2500 seconds- the reduced fuel flow is due to the use of atmosphere as propellant. However, our Thermal Turbojets rely *ENTIRELY* on the atmosphere for propulsion-mass, which means the rates ISP is what you get for exhaust velocity, and there is no possibility for a mix-up like this. A sea-level Exhaust Velocity of 1278.787 m/s (130.4 seconds ISP) is actually quite *low* for a real-life jet engine... (2) The atmospheric and velocity-curves of the stock jet engines are quite generous compared to real-life engines. KSP-Interstellar Thermal Turbojets have their own, much more balanced curves, however- so this is also not an issue. Thus, there is nothing overpowered about our current Thermal Turbojets, except that their engine mass may be a bit low (which is hard to realistically implement in KSP since jet engines hang entirely on the tail of a plane, instead of being built through the length of a fuselage. IF we gave the engines realistic masses, all planes built with them would become far too tail-heavy, and aerodynamically unstable as a result...) Regards, Northstar

Hold off on that adjustment- because if I am wrong about the relationship between altitude and Thrust (that is, maximum Thrust is observed on the runway, not at optimal speed/altitude) then the adjustment will actually need to be in the opposite direction (a 50% INCREASE in Thrust/MW). Regards, Northstar

Welcome to the forums Owen! Glad to have you aboard! Regards, Northstar

Glad to have you aboard Jethro420! Maximus97, that's not quite what people are talking about when they discuss the 32-bit memory limit. You may have a great graphics card and processor, and be able to play at full-graphics and with huge vessels without lag, but you will *NEVER* be able to exceed the 32-bit limit on RAM usage (even if you had 2 *trillion* GB of RAM) no matter how good your rig. You only hit this memory-limit with mods, but some mods are quite memory-intensive. ScanSat takes 1 GB alone, for instance- and IIRC, RemoteTech isn't much better for RAM usage... KSP-Interstellar (which is a great mode I use, help develop an Extension Config for, and highly recommend) also can get quite memory-intensive if you have a large Microwave Beamed Power network in place as it basically performs some of the same calculations as RemoteTech for Microwave Beamed Power... Linus 64-bit is the way to go if you really get mod-hungry! Way to go the extra mile for Kerbal Jethro! Regards, Northstar

OK, so I'm glad I decided to actually re-test with the new ThermalPower and Thrust/MW figures for the Thermal Turbojet... For 849.8416 MW of ThermalPower at 2750 K, the ThermalTurbojet "only" gets 320.4 kN of Thrust at 130.4 seconds ISP... That equates to: 0.377 kn/MW at 130.4 seconds For reference, the NERVA for 0.3 kN/MW of Thrust at 850 seconds Vacuum ISP... Using the equation (Power = 1/2 * Thrust * Exhaust Velocity) we can get an expected Thrust at this level of ThermalPower, but first we need to find the Thrust/MW at optimal ISP for the Thermal Turbojet so we are comparing apples to apples... Once again, the optimal ISP for a Thermal Turbojet is (2500/800) = 3.125 times as high as at sea-level... In KSP, jet engines already have a correct relationship between Thrust and ISP- fuel flow remains fixed, and Thrust increases/decreases with ISP. Here is a graph from some excellent analysis of this on Reddit: http://imgur.com/INHzu9P So, at optimal ISP: CURRENT/EXPECTED Thrust Production: 320.4 * 3.125 = 1001.25 kN CORRECT Thrust Production: 0.3 kN/MW * 849.8416 MW * 850/(130.4 * 3.125) = 531.8 kN Surprisingly, if I'm correct in extrapolating the behavior of stock jet engines to that of the Thermal Turbojet, the Thrust/Mw is actually nearly *twice* what it SHOULD be at sea-level... So, never mind that bit about increasing Thrust 20-25%? Sometimes the numbers REALLY surprise you when you actually do them out... Conclusion: A 46.9% REDUCTION in Thrust/MW for the Thermal Turbojet seems to be in order... Regards, Northstar

OK, so FreeThinker- a couple of questions about dependencies: (1) I notice that Community Resource Pack is currently a dependency, but you were concerned about them going with a 1 unit = 5 liters convention and possibly messing up the Extension Config in doing so... What do we actually rely on CRP for besides the CarbonDioxide (but *not* LiquidCO2) resource? (2) I noticed Regolithi is currently a dependency. I thought that was for the Propulsive Fluid Accumulator code, but one thing we learned from RoverDude's earlier posts was that it was not. What do we currently use Regolith for? Also, I've gotten quite confused about exactly where the Thermal Turbojet performance is now. It got buffed, then nerfed, and I want to make sure I'm running my numbers correctly. So, I'm going to test the parts again in the latest version, and report the changes that need to be made to the Thrust/MW based on the current, actual numbers. A 20-25% buff might not be the correct number: so hold off on implementing it if you haven't already... Regards, Northstar

Nice! Robert Zubrin is quite a character! Do you think you could tell us a little more about what the interview focuses on in the OP, though? Regards, Northstar