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About DBowman

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    Sr. Spacecraft Engineer

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  1. I've had some reasonable success with LDV (achieved orbit, and able to improve excess prop via optimizing), but my method is a bit "brittle", and I really want to find a global maxima, not the local one I was near. Could you advise me on a more flexible way to get it done? My current method is to have a few "pitch segments" which I setup by hand (intending to let the optimizer tweak them later), the last one has -ve pitch and terminates when Ap alt reaches 250 km. The optimizer then controls pitch and duration for the circularization burn at Ap. If I (or the optimizer) tweaks one of the p
  2. I have no problem with that! (well it's a bit tedious when you consider all the shiny math deriving the plot itself, maybe the data tip should have the UT seconds also? but I can do the KSPTOT date to UT seconds conversion no problems) With 365 days the KSPTOT year matches the UT seconds of the other tool. So that is excellent. Can I ask what the porkchop does re the inclination of E & C? I'd assumed, and am really hoping it respects the inclinations and isn't simplifying to coplanar.
  3. Hi, sweet work with the textures. I have a hand crafted MAV trajectory that I can tweak within limits and see on the order of 5% prop use efficiency, the optimizer only sets the "get Ap pitch" and final circularization pitch and duration. if I push it too far the termination conditions don't happen at the right time and I have to rejig it manually. It's okay for now. I treid again with linear tangent, it cheerfully gives me a burn at 89 degrees all the way, I cannot figure how to tune the parameters so it's close. But the pitch program version is okay for now. Topic shift to Ceres.
  4. Ah! awesome! now I see that I am launching due North man... (assuming planet blue arrow out the top is N) during the big coast to Ap roll and yaw angle both seem to flip between 0 and 360 randomly, I guess that doesn't really matter, but at the Ap burn they are both somehow set to 180, which I guess explains the "retrograde burn", I'm upside down and going backwards for some reason. Setting roll to constant 90 in initial steering model and having "continuity" checked only seems to effect the first event duration. After that I see roll = 90 in the graph but the trajectory starts heading N
  5. NASAs POST2 - I guess giving away hypersonic trajectory simulators is not the done thing. Thanks for the RSS bodies.ini and your inputs. I managed to put together a .mat that gets into a 250x250 LMO with aero effects. I put some graphs and the .mat here (https://drive.google.com/file/d/1qaKIbTivOiqO-_CpD4lk8BKI5d9s9SGt/view?usp=sharing) Good things: 700 kg dry + 2-ton prop gets up with 47 kg prop left over. maxQ 170 Pa. Without the first event 10 km vertical it's 250-ish so aero acts like I'd expect. My bads: you can see after attaining Ap=205 km it decays a few km, the A
  6. I just want to get a sanity check on the ascent + aero-effects, I thought RSS might not be as sensitive to some parameters are LVD. NASA papers always reference a "protected" sw package that only gov employees "with a good reason" can get access to. One of those cases where you have an idea and keep following the loose ends.
  7. I recall, since I need Mars you are thinking RSS or Copernicus data will be okay? I've no idea how suitable their temp & sun mult data is. I have Mars (alt,temp) data, but not yet sun mult
  8. okay thanks, do you know what these represent? some googling => "something to do with scattering" (from Kerbin) atmoTempSunMultAlts = 0.00000000000,8.81521972656,16.05038867188,25.72923437500,37.87944140625,57.44012500000,63.90271875000,70.00000000000 atmoTempSunMults = 1.00000000000,0.30000001192,0.00000000000,0.00000000000,0.20000000298,0.20000000298,1.00000000000,1.20000004768 https://github.com/KSP-RO/RealSolarSystem/blob/master/GameData/RealSolarSystem/RSSKopernicus/Mars/Mars.cfg has some data for Mars, do you have a better source?
  9. I coded a pitch program by hand. Pitch hard, Pitch gently till Ap hits 250, coast till at Ap alt, optimize pitch and time for circularizing burn constrained by semi major axis. That gets a 700 kg vehicle up with 740 kg of leftover prop from 4-ton initial, so I figure it's putting into orbit double the mass it needs to, so probably 2-ton of initial prop is enough. Maybe even better if/when I figure out how to optimize the pitch segments. Seems like one advantage of the linear tangent stuff is a smaller number of optimization params, and that they are more naturally linked by partial derivatives
  10. So many problems! Thanks for looking at it for me. re #4 rocket equation and references for LMO mean thrust and prop should be okay or close, but that's why I want to simulate with gravity and aero. I've been playing around with the .mat you provided. I cannot get it to not push Ap out to 450 km before driving it back down again, which tells me it's way off optimal, the pitch control seems to vary only slowly at first, but my gut says pitch over hard early and ease back the rate of change. The graph of Dynamic pressure doesn't start till t=270, which is about where it get out
  11. Okay I loaded a SolarSytem bodies and tried to recreate your Mun LDV, but for Mars. I have shared them here https://drive.google.com/file/d/1ae2BXL5JWITsOJX5t4bo2M37uDKTSQ8z/view?usp=sharing well it seems to kind of end up somewhere... but I cannot figure out what is going on Could you please take a look and see if you can help me out? I'm shooting for a 250x250 LMO
  12. Ah, that is kind of what I was afraid of. In my case it's not too bad, the mission is a few actions/events and my vehicle is simple, but it would be hard on someone doing something complex and finding a trivial error in the bodies file. I guess the "hack" you suggest would cover simple point errors. Thanks for your help. I'll start one from scratch in RealSolarSystemBodies.ini. Do you want to take contributions to fleshing out the real solar system? Mars pressure heights? Are the atmos temperatures likely to be significant? Mars is pretty thin? I just want to see an SSTO get u
  13. Thanks 2: yep I'd figured that out 1: parentID missing for Jupiter out, so I fixed those. Start KSPTOT: SolarSystem in porkchop plotter, open LVD: SolarSystem in vehicle initial state set frame options, Load your Mun .mat: KerbalSolarSystem in vehicle initial state set frame options. Um so how does one replace the solar system in an existing mission design? Do I need to start from scratch, replicating your mission .mat but in RealSolarSystem? Does that mean that if one is in the middle of designing a complex mission and discovers a small error in bodies (e.g. some pressure height err
  14. Well, learning about what's wrong and how to see what's wrong, but still stuck... I added a "Drag" sequential even to turn it on, I didn't see where you had turned it off. Using the graphs I can see that the vehicle starts at 0 and sinks from there. The pitch angle is a constant 85 degrees, which seems "okay for now". I looked at throttle and it's set constant at around 22%, so the TWR starts at 0.265 and increases as prop is burnt. 3 t m0 so for Mars 11,133 kN required for TWR 1, throttle 0.22*35kN = 7,700 kN should be higher than 0.26 TWR. hmm Atmospheric pressure is 101 kPa.
  15. Cool! I started it up. I guess it has bodies.ini built in? loaded the mun.mat fine, what is the orange plume? failed steering optimization attempts? At first graphical analysis plots of altitude seemed to show nothing, but after running optimize mission the plots all had data. hmm it wanted network access, said something about starting parallel workers, firewall popped, and it seemed to run anyway before I'd decided what to do. I copied your mun.mat, closed LDV, loaded my bodies.ini which has Kerbin replaced by Mars data, opened LDV, loaded munCopy.mat, edited vehicle initial
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