Jimbodiah Posted February 2, 2016 Share Posted February 2, 2016 Looking good!!! That first one has is the Atlas V right? It should have a wide flat top, not a single point like traditional SRBs. It's impossible to say though from just the profile. Quote Link to comment Share on other sites More sharing options...
Shadowmage Posted February 2, 2016 Author Share Posted February 2, 2016 4 minutes ago, Jimbodiah said: Looking good!!! That first one has is the Atlas V right? It should have a wide flat top, not a single point like traditional SRBs. It's impossible to say though from just the profile. I'm going to need cross-sectional diagrams then (a series of cross section profiles at regular height intervals), as I cannot infer or derive this information from the images provided. If you cannot find these, then it will likely end up being a regular pointed nosecone like the rest (or just not done at all). Quote Link to comment Share on other sites More sharing options...
Jimbodiah Posted February 2, 2016 Share Posted February 2, 2016 No such thing exists unless I get CAD files for the actual SRBs. Ah well, RealScale Boosters has them in their mod, I can just use those together with tweakscale as I am doing now. Quote Link to comment Share on other sites More sharing options...
Jimbodiah Posted February 2, 2016 Share Posted February 2, 2016 PS, they also use CoPOffset and CoMOffset, I think to keep boosters from flailing around upon separation. When boosters are released, they stay straight and give a nice clean separation. Quote Link to comment Share on other sites More sharing options...
Shadowmage Posted February 2, 2016 Author Share Posted February 2, 2016 (edited) 17 minutes ago, Jimbodiah said: No such thing exists unless I get CAD files for the actual SRBs. Ah well, RealScale Boosters has them in their mod, I can just use those together with tweakscale as I am doing now. Aye, I was unable to find any such information either; generally that kind of detailed information doesn't exist in the public-domain for... well, anything. If it could be used to re-create it (whatever -it- is), the information is generally locked up pretty tight. I've done a 'best guess' based on a few side-view images... but... without proper information, this is about as close as I can get: (I -really- dislike guessing about geometry.... yes I know, I'm terrible at modeling without engineering-level diagrams and schematics to work from). Based on: What I was looking for was an MRI-like layer-by-layer diagram of the cross-sections; it is the only way to accurately reproduce complex 3-dimensional shapes from 2-dimensional drawings -- as you said, it is impossible to tell a cross section from a 2-d image; even multiple 2d images, you can tell how wide the widest point is, but you cannot tell how far from the camera it is. Edited February 2, 2016 by Shadowmage Quote Link to comment Share on other sites More sharing options...
Jimbodiah Posted February 2, 2016 Share Posted February 2, 2016 Looks great to me!!! I don´t think anyone will demand a 100% replica. Quote Link to comment Share on other sites More sharing options...
Shadowmage Posted February 2, 2016 Author Share Posted February 2, 2016 Okay, so apparently Near-Future / Cryo-engines tanks are intentionally double-filled with fuel: However, being a physic-based game, I feel this is wrong. A major part of the difficulty and balance of LH2 is that it is so light. Doubling the density only makes the fuel far too powerful, and results in rockets half the size that they should be. Rockets in KSP are already short enough, they don't need any help being shorter. In short -- I will -not- be using double-density/0.5 liter units for LqdHydrogen. If you are okay with cheating at physics, feel free to use other mods' LH2 tanks. But 32 cubic meters is 32 cubic meters, and can only hold 32k liters, regardless of what matter those liters consist of; that is physics. However, I will state that this is entirely configurable through the SSTU fuel type definitions. So you could patch this behavior in if you would like -- but I will not provide those patches, nor offer any support for installs using them. Quote Link to comment Share on other sites More sharing options...
Shadowmage Posted February 2, 2016 Author Share Posted February 2, 2016 (edited) (Updated with Jarvis nosecone) Semi-final nosecone geometry and selection: Left to right -- Atlas HLV, Shuttle/Delta, Jarvis, Arianne, Atlas-Pointed, Atlas-Wide. Will likely move on to working on the basic re-usable segment geometry next -- nozzles and upper-skirt (parachute/avionics) segments. After that will be working on the main segments for each type of SRB setup. Edited February 2, 2016 by Shadowmage Quote Link to comment Share on other sites More sharing options...
Jimbodiah Posted February 2, 2016 Share Posted February 2, 2016 (edited) No problem with the current setup, I use a lot of LH engines in my stages. Just wondering why they had twice the units inside (or sstu only half), seeing as LH2 is quite new to this mod I thought it may have been an oversight. I saw a ton of calculations and spreadsheets come by when NF were balancing their engines and new tanks. Guess "balance" was not in terms of realistic volumes. [edit] Kind of makes you wonder why they were adamant about a 15:1 ratio then??? Edited February 2, 2016 by Jimbodiah Quote Link to comment Share on other sites More sharing options...
Shadowmage Posted February 2, 2016 Author Share Posted February 2, 2016 9 minutes ago, Jimbodiah said: No problem with the current setup, I use a lot of LH engines in my stages. Just wondering why they had twice the units inside (or sstu only half), seeing as LH2 is quite new to this mod I thought it may have been an oversight. I saw a ton of calculations and spreadsheets come by when NF were balancing their engines and new tanks. Guess "balance" was not in terms of realistic volumes. [edit] Kind of makes you wonder why they were adamant about a 15:1 ratio then??? Well, the ratio and the density effect the performance of the rocket differently; though through similar mechanics (tankage mass for a given volume of fuel), but in opposite directions. More dense LH2 = heavier fuel per volume unit = smaller tanks for a given mass of fuel = lighter tanks from structural mass. More LH2 for each O for the ratio = lighter fuel mixture per volume unit = larger tanks for a given mass of fuel = heavier tanks from structural mass. It really is beginning to boggle my mind -- and these are perfect examples of why I didn't really want to get into the LH2 stuff to begin with.... with it not being a stock managed resource, people decide to 'do their own thing' and throw physics out the window... and now I can either adjust my balance to conform (not happening), deal with complaints of unbalanced parts (maybe), or remove the LH2 patch entirely (seeming more likely with the recent revelations). Sad, as I was just getting to the point where I was ready to swap the LH2 configs over to be the default and start balancing thrust/etc for it. Now I've got to rethink some pretty major portions of the balance. Quote Link to comment Share on other sites More sharing options...
Jimbodiah Posted February 2, 2016 Share Posted February 2, 2016 5 minutes ago, Shadowmage said: More LH2 for each O for the ratio = lighter fuel mixture per volume unit = larger tanks for a given mass of fuel = heavier tanks from structural mass. Yeah, I pointed this out to them as tanks grew about 50% in size because of the switch but I had higher dV because of the lighter mixture, despite them being larger to hold the same dV. I brought up the point in the SSTU thread once when you were thinking of adding LH, but I didn't look into it further then thinking I may have just been "seeing things". This kind of is a downer for me, that "balance" after all those calculations etc in their thread was anything but realistic. Also hard to phathom why they wanted boil-off etc to make it more realistic as a "balancing" factor vs stock fuels with lower ISPs. Just weird... I still think LH is a good thing, as it shows you that tanks need to be bigger when using LH2 vs when using Kersone (LF). LF is smaller but heavier and engines are less efficient. LH is lighter and thus larger, but engines are more efficient and optionally you have boil-off. Sort of like "real-fuels light". You could always go back to 10:1 and just do your own thing. Quote Link to comment Share on other sites More sharing options...
Jimbodiah Posted February 2, 2016 Share Posted February 2, 2016 (edited) I just did a comparisson to see the differences. Each setup was chosen to give ±4200 dV at around the same thrust. Left to Right: LF/O (46t), LH2 CryoTanks 2:1 (36.3t), LH2 Stock 1:1 (65.5t), LH2 SSTU (30.4t) The stock setup needs more fuel due to extra tank dry-weight which compounds when you add more of them. SSTU has the lowest dry-weight which makes it more efficient than with stock tanks, requiring less fuel. I can see why CryoTanks changed to the 2x ratio, as it would not be playable with stock tanks otherwise in the sense that I can imagine people not using the mod due to all the extra tanks and weight when being constrained to using other stock parts. Yes, using 3.75m tanks does make it a bit more favorable in terms of height, but weight is still comparable. Edited February 2, 2016 by Jimbodiah Quote Link to comment Share on other sites More sharing options...
Shadowmage Posted February 2, 2016 Author Share Posted February 2, 2016 If that 2nd tank on the right is the Cryo-tanks LH2/O setup (orange+short gray tank) -- I would say that it is -far- smaller than it should be (though, to be fair, it -does- look Kerbal...). Initial pass at SRB nozzles (Left-to-Right: Atlas, Shuttle, Arianne): Thinking of making a vacuum variant on the nozzles, but at this point I mostly just weighting the pros/cons of it (would require additional special support to change the ISP/curve depending upon the mount selected; potentially introducing difficult-to-patch stuff for RO). Quote Link to comment Share on other sites More sharing options...
Shadowmage Posted February 2, 2016 Author Share Posted February 2, 2016 23 minutes ago, Jimbodiah said: I just did a comparisson to see the differences. Each setup was chosen to give ±4200 dV at around the same thrust. Left to Right: LF/O (46t), LH2 CryoTanks 2:1 (36.3t), LH2 Stock 1:1 (65.5t), LH2 SSTU (30.4t) The stock setup needs more fuel due to extra tank dry-weight which compounds when you add more of them. SSTU has the lowest dry-weight which makes it more efficient than with stock tanks, requiring less fuel. I can see why CryoTanks changed to the 2x ratio, as it would not be playable with stock tanks otherwise in the sense that I can imagine people not using the mod due to all the extra tanks and weight when being constrained to using other stock parts. Yes, using 3.75m tanks does make it a bit more favorable in terms of height, but weight is still comparable. The 2:1 compression almost makes a bit more sense if they were balancing things vs. the stock-tanks dry-masses (which are listed in the configs). But that is still the (IMO) wrong way to do things -- the right way would be to change the tank dry masses to make it appropriate for LH2 (at the plugin/module level). Not 'compress' an incompressible fluid to make it fit vs the dry weight of the tank... that is just silly. Yes, an LH2/O tank of the same size will weigh less than a KLOX tank; it has less mass of fuel to support. However for the same mass of fuel the LH2 tank should have a slightly worse -mass fraction- compared to KLOX when comparing purely on a fuel-mass-to-dry-mass basis. Quote Link to comment Share on other sites More sharing options...
Jimbodiah Posted February 3, 2016 Share Posted February 3, 2016 Judging by the picture, I think you have a good compromise in terms of size vs capacity. It's exactly in between CryoTanks' kerbalist balance and the inflated stock parts stack. Maybe increase dry-weight a bit to balance it out (needing a bit more size/fuel to compensate), but the main difference is from having to use four stock tanks vs just one SSTU. Quote Link to comment Share on other sites More sharing options...
JoseEduardo Posted February 3, 2016 Share Posted February 3, 2016 do you have plans for UA 1205 and 1207 or the fact that they were angled puts them out? they would fit well with the, already in, Saturn parts (Saturn MLV projects), and could be used for Titan if you ever make the LR-87 and LR-91, of course Quote Link to comment Share on other sites More sharing options...
Jimbodiah Posted February 3, 2016 Share Posted February 3, 2016 The Delta II boosters are all angled as well. Angling should not be a problem for a single part, but might indeed be a challenge for a modular part? Quote Link to comment Share on other sites More sharing options...
VenomousRequiem Posted February 3, 2016 Share Posted February 3, 2016 18 minutes ago, JoseEduardo said: do you have plans for UA 1205 and 1207 or the fact that they were angled puts them out? they would fit well with the, already in, Saturn parts (Saturn MLV projects), and could be used for Titan if you ever make the LR-87 and LR-91, of course Some shameless advertising here, BDB has most of the variants of the Titan boosters, as well as Titan itself in all variants except 3, but 3 can be made. Quote Link to comment Share on other sites More sharing options...
JoseEduardo Posted February 3, 2016 Share Posted February 3, 2016 10 minutes ago, VenomousRequiem said: Some shameless advertising here, BDB has most of the variants of the Titan boosters, as well as Titan itself in all variants except 3, but 3 can be made. just checked there, the Titan main rocket looks sweet, but I couldn't help noticing that there is no pic of the UA 1205 or 1207 SRBs, are they included? Quote Link to comment Share on other sites More sharing options...
01010101lzy Posted February 3, 2016 Share Posted February 3, 2016 Do you have plans making an X-2200 Aerospike Engine? It may be convenient in making a shuttle or so. Quote Link to comment Share on other sites More sharing options...
VenomousRequiem Posted February 3, 2016 Share Posted February 3, 2016 36 minutes ago, JoseEduardo said: just checked there, the Titan main rocket looks sweet, but I couldn't help noticing that there is no pic of the UA 1205 or 1207 SRBs, are they included? If it's a Titan SRB, I'm going to go ahead and say yes. There's 2 segment, 5 segment, 7 segment, and the 7 segment USRMs. Quote Link to comment Share on other sites More sharing options...
01010101lzy Posted February 3, 2016 Share Posted February 3, 2016 57 minutes ago, Jimbodiah said: The Delta II boosters are all angled as well. Angling should not be a problem for a single part, but might indeed be a challenge for a modular part? Maybe adding a angling slide-bar could help... But I'll just wait for the release. Quote Link to comment Share on other sites More sharing options...
Shadowmage Posted February 3, 2016 Author Share Posted February 3, 2016 15 hours ago, Jimbodiah said: Judging by the picture, I think you have a good compromise in terms of size vs capacity. It's exactly in between CryoTanks' kerbalist balance and the inflated stock parts stack. Maybe increase dry-weight a bit to balance it out (needing a bit more size/fuel to compensate), but the main difference is from having to use four stock tanks vs just one SSTU. Noted; yea, the balance on the LH2 stuff is not final... or even -balanced- yet. I literally just slapped some estimates/guesses in for the mass factor (in fact it currently uses the same as stock fuels, on a mass-per-mass basis). Will know more regarding how it should be balanced after I get a few more engines / tank parts done. Though you should probably not expect it to change until post 1.1, as that is when I will be doing the full balance passes. 13 hours ago, JoseEduardo said: do you have plans for UA 1205 and 1207 or the fact that they were angled puts them out? they would fit well with the, already in, Saturn parts (Saturn MLV projects), and could be used for Titan if you ever make the LR-87 and LR-91, of course 13 hours ago, Jimbodiah said: The Delta II boosters are all angled as well. Angling should not be a problem for a single part, but might indeed be a challenge for a modular part? 12 hours ago, 01010101lzy said: Maybe adding a angling slide-bar could help... But I'll just wait for the release. I have been debating adding support for angled boosters. The main problem I run into is angled boosters are intended to be used only on a specific launch-vehicle; the angle of the nozzle is set to run through the average COM of the main core stage to impart minimal torque and maximize usable thrust. Obviously this would not work out with stock KSP mechanics and its randomly designed rockets. So, I need to decide before I go any further on the nozzle/geometry end of things if angled nozzles is something I will support. -IF- I do include angled nozzles, I will have to find a way to add an in-editor adjustment for them; there is no way around it. Supporting angled nozzles would require specially compiled nozzles models (mounts) that include a reference thrust transform, gimbal transform, and information regarding acceptable gimbal range (both in-editor adjustment and in-flight gimbal range; which can/should be different). Including the transforms is not a problem, as the models have not been built yet; but this would exclude using any 'generic' models as nozzles, or any other mods' models for nozzles, unless they included the proper gimbal and thrust transforms (though, I'm not aware of any other mods' that add SRB nozzles, so... probably not an issue). Mostly this would require, in addition to the work that I've already done on the plugin/config/etc: Plugin-level support for adjusting reference angle for the gimbal while in the editor (adjustment slider, likely only on a single axis). Plugin-level support for repositioning and re-orienting gimbal and thrust transform to match the reference transforms from the model. Model-level support -- needs to have reference transforms for gimbal and thrust. Config-level support -- need to have config data for each nozzle listing its gimbal range (editor adjust and in-flight use) versus the reference transform. And at this point if I'm going through all the work to do that stuff for the nozzles, I might as well investigate adding variable ISP/atmo curves for each nozzle as well -- would result in a decent range of performance depending upon which nozzle/etc was selected. Would need to find solid information regarding SRB performance stats for various nozzles. Would also need to find a way to disable this mechanic when RO is installed. Will be debating over this stuff a bit today while working on the rest of the SRB geometry. Will likely know in the next day or two how I'm going to proceed. What it might come down to in the end is 'how many nozzle models do I feel like making?' Honestly, even the existing/planned three is pushing my patience. I mean... its an SRB...how many variants are really needed? Only one.... Hmm... perhaps some of you guys need to learn how to model this stuff yourselves? 13 hours ago, 01010101lzy said: Do you have plans making an X-2200 Aerospike Engine? It may be convenient in making a shuttle or so. The linear aerospike engine? No, it has extremely limited application on rockets. And I have no interest in doing a generic aero parts series (unless SQUAD fixes the part-count bloat from mandating symmetry be used for wings/etc). Quote Link to comment Share on other sites More sharing options...
Jimbodiah Posted February 3, 2016 Share Posted February 3, 2016 Gheghe, we only need two engines and one tank as well No issue with just downward thrust on my end. Quote Link to comment Share on other sites More sharing options...
JoseEduardo Posted February 3, 2016 Share Posted February 3, 2016 about angled SRBs, I'm not 100% sure of that, but I remember reading that the Saturn MLV concepts, and other post-Apollo designs were going to use unchanged versions of the UA 1205 and 1207, so I don't think they were adjustables I might be wrong though.... Quote Link to comment Share on other sites More sharing options...
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