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About DBowman

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    Sr. Spacecraft Engineer
  1. awesome @Vaga thanks very much. Re the tech tree - I'd seat of the pantsed the tech levels looking referring what I thought were 'comparable' parts, also I think closed life support is going to be 'hard to get right'. Given what you say and the 'game nature' of the tech tree I'll review that aspect of things when I do an update. Thanks again.
  2. Oh wow I knew I'd been 'doing other things' but I've missed a few TACLS releases - if @Vaga or anyone else has / gets positive or negative testing info let me know and I'll update spacedoc and/or fix it. thanks !
  3. @theJesuit hey thanks for the inputs. The photon computation sounds good - does it handle planetary occultation? For sure taking Kerbalism green house 'module' section then scaling it and adding to gigantor would get you a big green array that worked with Kerbalism. If you wanted to make it more Solylent-ish you could then get the helfire part consuming some of the resources that feed Kerbalism green house and modify the new Kerbalism Green Gigantor module to remove some inputs and replace with slurry. @Waxing_Kibbous I think you probably want do MODULE:NEEDS[ProfileSimplified]:FOR[Kerbalism] rather than put it on the @PART. I guess you have Soylent installed and are not trying to 'pull out the bits you want'? The SoylentResources.cfg is needed to define the resources - bad things happen if it's not there. The SoylentConfig.cfg holds some ratios that get used by newer parts - look at DarkGreenL.cfg to see how - depending how fully you wanted to Kerbalize Soylent you might want to put Kerbalism ratios on the Config object and reference them from parts. I guess it's possible that Kerbalisms 'Greenhouse' module has some resource hardcodings, maybe insolation just effects some 'rate' multiplier inside it. If I was doing it I'd start by just adding a straight copy of the Greenhouse module to big green and see it works. Then add a Soylent output resource (even starter) and see that the result will produce starter into a starter tank. Then make helfire box consume Kerbalism resouces and produce slurry. Then Modify big green to use slurry. Do it in little steps so you know what went wrong as soon as it goes wrong.
  4. [1.2] Proton-M / Breeze-M

    Gratz on the dream job! Modelling and Science! If you are happy to share any details that'd be cool. Thanks for all the work you have sunk (so far...).
  5. Ah - thanks - good to know (sad cause it makes it harder not to melt off wafers). After I get the basic scheme working I can go back and turn some of the 'constants' into lookups by temperature. Also I need to work out a starting temp, but that one should be K such that sun heating + Earth heating and radiative cooling are equal.
  6. yep I'm already there. Question - heat of fusion - after the metal reaches melting point you have to put another 'heat of fusion' Joules into it for it to liquify. So can I rely on this? having the Pt solid but with contained Joules between that required to melt it and to liquify it? Once it liquifies I can just remove that wafer from the simulation and apply the reentry heating to the next remaining wafer? edit - forgot the most important part Fouriers law for thermal conduction has energy flow depending on temperature gradient - that would mean the energy flow out of the wafer would be constant as the joules contained by it increased over melting temperature - but it seems like if there are more joules there then they should flow more into the next wafer even though the temp is clamped. Is it that Fouriers law only works while its solid below melting point? or can one 'just' rewrite it as a Joule gradient rather than a temperature gradient?
  7. Any sanity checks are welcome. I couldn't find any magic formula in college/uni level thermo papers that would let me plug max flux, dimensions, and material properties and have it spit out a Kelvin over depth through a plate of material - except once it reached 'thermal equilibrium' with a temp on each side of the material. Spending a few seconds at 300 g while being blasted with 20 MW/m^2 is not equilibrium. So I went to 'first principles' and a spreadsheet. But if anyone knows a magic formula that would be great. treat the reentering slab as many wafer thin slices (1000 in 4.66cm 1kg per wafer of a 1000kg 1m2 slab) let flux W/m2 = J/(sm2) be dumped into wafer 0 every slice of time - so track the J in the wafer specific heat J/(K kg) can then compute a temperature K for the wafer chose time slice size so that temp is only a fraction of the melting temp (0.001 sec) the next time tick J will move out of wafer 0 into wafer 1 best case the J in the two wafers will equalise but could be limited by: time s * thermal conductivity J/(smK) * temp difference K / distance m = J out of wafer 0 - this seems to be 10 times the above do all the J out calcs, then apply wafer n-1 J out as wafer n J in - now we know J in for wafer 1 at time slice 1 repeat the logic for each wafer for each time the spreadsheet quickly becomes 'unwieldy'. If I didn't mess up then the slab would start melting off after 0.16 seconds of peak heat and lose around 40 kg during peak heating, probably after than radiative cooling would stabilise things. I could have messed up: I misunderstood the heat transport from wafer to wafer typo-ed the spreadsheet I've only used a few wafers so far - makes it look artificially good time slice it too big and artificially limits heat transport - maybe I have to choose dt to be where thermal conductivity is coming into play I guess I have to write a program if I'm going to slice time 10 times finer and compute all the wafers.
  8. Yeah, I just ignored that - as far as I can tell from KSP you just rip through the atmosphere but are left with a subsequent Pe in the atmosphere. I think some warhead reentry vehicles were metal. Partly it a g-force, max, total heat tradeoff, people are squishy. Also if you are bringing your heat shield it has to be light, but in my case the heat shield is the cargo. My goal is a real life conservative approximation - so it can be not too accurate as long as it's an overestimate of heat and underestimate of radiation & heat sink effect. This has some links to Mars entry craft where front face got 2 MW/m2 but back face gets only 1 or 5 kW/m2 - so I guess it's pretty safe to set my back face flux to 0.25 to 1 % of front face. I could treat front and back as independent disks and see how that goes.
  9. I know - funny. Thanks for the links I'll check em out. For many entry angles I see enough heat to more than melt the lump => it will melt and 'run off' and be lost, for some angles it wont melt it all but the remainder impacts 'very fast'. I want to achieve a 'no melt off' non destructive to the lump impact velocity. Re the foam it sounds right but: too steep an entry might pancake it => not foam any more and who knows what aero consequences - I can easy get 400g max deceleration - maybe metal foam laughs at that you'd have to worry that the heat is now impinging on a small mass of material that has to transport heat through a much smaller amount of material - so I worry it might make melt off worse if the heat is 'too high'. Modelling a foam sounds 'not simple' maybe someone has done the work and has some kind of approximation I can work with.
  10. I'm building a simple spreadsheet model of reentry and I'm looking for any hints, advice, comments, pointers, etc. I've read all over the place conflicting opinions on the question of 'can you reenter big lumps of naked metal in a safe and recoverable way'; responses range from 'no we'd have to place the material in reentry capsules' through 'sure just make a foam/fractal low density lump'. We find lumps of metal that have reentered but usually (always?) don't know what the original mass was. I thought I'd explore the question for myself. The basic reentry heating math I'm getting from this FAA (really?) doc . I can play with entry velocity and angle. So far I've used a simple scale height / exponential atmosphere density model, but I could move to on of the more accurate standard models when it was worth it. I'm playing with a 1000 kg lump, sphere for simplicity, platinum ( $$, solid is about 40 cm in diameter ) I can make it hollow with different wall thickness to play with ballistic coefficient I can kind of match the results the paper has, I plan to find some other sources to cross check later. I can compute W/m2 heat flux I'm assuming that it impinges all sides of the reentering object. The linked doc says for Earth atmosphere sub 15 km/s convection dominates heat transfer which makes me think it might be more accurate to use 'area facing the flow' to take up heat (i.e. less m2 => less total heat). what do you think? My current model cannot find a trajectory that won't melt the whole mass (and more - unless it impacts at like 7 km/s) but my heat may be incorrectly high (see above) and I need to account for radiation of heat from the hot surface heat conduction through the mass. If the total heat is not going to melt the whole ball then the question becomes can the surface transport heat fast enough to be below melting point. calcing radiation as if the surface was at melting point would get rid of a big proportion of the heat (and it would very quickly get that hot) I've found some heat transport equations. Working with hollow sphere looks 'simple enough' and if the material can transport heat away from the surface fast enough it looks like you might be able to arrange to impact a ball of hot but not melted metal. However if I should move to only receiving heat from the flow facing surface then the radiation becomes more complex, maybe: I can conservatively pretend only the flow facing surface radiates any heat I could pretend the lump is a flat disk for heat sink purposes (with some mass removed for 'back structure' for aerodynamic stability etc, patch of a sphere facing the flow and a conical back structure) Anyway doing a full finite element analysis / computational fluid dynamics style treatment is more than I want to (could) do but it seems like a conservative approximation should be doable. Maybe there is already some online tool that does this kind of thing?
  11. Can the Soyuz Still go to the moon ?

    Launch the Proton carrying a boost stage like Briz-M, lauch a regular Soyuz on a Soyuz (maybe choosing different names for launchers and space craft would be less confusing), dock Soyuz to Briz and boost to Luna. It could sure do a flyby with the OM, it probably couldn't capture. Something higher thrust than Briz might be needed to avoid Pe kick time in the van allen belts (depends trajectory details etc). Another Briz could launch into rendezvous with the free return trajectory Soyuz (three days to fiddle with the rendezvous), Soyuz swaps Briz (with fail safe free return) and now has deltaV to capture into lunar orbit and (probably) get an Earth return. Thats like 300M USD of launchers - excludes vehicle mods (luna return reentry, navigation, etc) etc. A similar scheme could get a lander there.
  12. Your parts and interiors look loverly. Nice Eve deployment in your 'promo album' - and expando hab - nice. So I guess your plan is to just add Soylent style resource processing to your algae container? All the other LS resource processing comes from whatever TAC, USI, etc style integration you have already done? My .cfgs are pretty straightforward. I guess your part is most similar to my newer 'dark' (e not light driven) parts. For them I've started using an 'inheritance hierarchy' style, making some parts a copy & modify of a parent part and just adding model and resource processing scaling (e.g. DarkRedS.cfg scales DarkRedM.cfg etc) just to move the 'magic' numbers & most of the processing definition to one place - DarkGreenL.cfg is the root of that attempt and references the actual magic numbers in SoylentConfig.cfg. I tried to make those balance with the 'host' LS and then 'backed out' human scale realistic mass & volume for the parts. You could take a similar approach and 'base' your part .cfg on one of mine (add what scaling you think appropriate) and it will get any change I make 'for free' (any mistakes also). Or you could make your .cfg a 'base' and ref my config for the magic numbers, and get any changes there 'for free'. Or just cpy paste the resource processing bits into your config. I'll give KPBS a shout out in Soylent OP when you are happy. I've skimmed Kerbalism and it looks great. I should add support, and I'll look at whats involved - but it might take a while to get to what with some irl stuff. If you have the skillz I'd be happy for you to take a look and tell me what you think is involved.
  13. Can the Soyuz Still go to the moon ?

    I bet reckon you could probably cobble together a moon mission based on existing Russian vehicles with some 'mods' ( e.g. Soyuz reentry++ ) and a new lander. I've not done the math but a Soyuz + a Proton/Briz (playing CSM) would probably get you to low lunar orbit with earth return propellant left over, use the same two launcher (Soyuz + Proton) plan to send a new lunar lander and do the LEM & CSM rendezvous in LLO. Still that's only about 60 ton in LEO so maybe not enough. This has a survey of Russian proposed Soyuz replacements.
  14. Blue Origin Thread (merged)

    one of the 'etc's? - they are not going to get to a NEO and back in 30 days - oh duh it's flyby of a captured one in cislunar space.
  15. Blue Origin Thread (merged)

    If it can get to a NEO ( as planned for EM-2, http://neo.jpl.nasa.gov/cgi-bin/nhats ) then it probably has the deltaV for a Venus Mars flyby ( assuming you can jam enough LS into it by dropping crew size etc etc etc ). This Venus Mars flyby I found using @PLAD's Flyby Finder passes Mars during Trump's ( potential ) second term and returns to Earth a couple days before the next President is sworn in.