Patched conics is when you switch between central bodies as you move between spheres of influence, but that's not how porkchop plots are typically generated. Do you mean "conic sections?"EasyPork does its (admittedly rough) convergence in three iterations, but other algorithms typically take 8-15 iterations to achieve machine level precision. Let me see if I can dig up some citations.Fun fact, but all Lambert Solvers are 2D! The 3D ones just flatten the three points (origin/Sun/destination) onto a 2D plane first.

The way I understand things, generally a porkchop plotter is used to generate a "Ten Thousand Foot" overview of transit windows, and then for the actual planning you'll use a more accurate numerical orbit propagation and optimization tool like GMAT. So essentially the plotter only need to get you within a couple days of the optimal window, at which point other software tools take over from there.I'm having a bit of trouble understanding fully, but if you care to PM your code I'd be happy to give up any hints or pointers I can muster (in strict confidence of course).Dug up some citations, as mentioned earlier.https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=27636d0fcdd957b13d2c566ef111aa34a5b3d81bhttps://indico.esa.int/event/111/contributions/321/attachments/579/624/Lambert_ICATT.pdfhttps://arxiv.org/abs/1403.2705

// radii[] are a list of radiuses, typically fixed delta but don't need to be const tangential = oldTangentialVelocity * oldRadius / radii[\i] const magnitudeSquared = oldC3 + 2 * mu / radii[\i] const radialSquared = magnitudeSquared - Math.pow(tangential,2) radial = Math.sqrt(radial) const elapsedTime = Math.abs((oldRadius - radii[\i]) / ((oldRadialVelocity + radial) / 2 ))

Quote from: Twark_Main on 05/22/2024 06:38 amThe way I understand things, generally a porkchop plotter is used to generate a "Ten Thousand Foot" overview of transit windows, and then for the actual planning you'll use a more accurate numerical orbit propagation and optimization tool like GMAT. So essentially the plotter only need to get you within a couple days of the optimal window, at which point other software tools take over from there.I'm having a bit of trouble understanding fully, but if you care to PM your code I'd be happy to give up any hints or pointers I can muster (in strict confidence of course).Dug up some citations, as mentioned earlier.https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=27636d0fcdd957b13d2c566ef111aa34a5b3d81bhttps://indico.esa.int/event/111/contributions/321/attachments/579/624/Lambert_ICATT.pdfhttps://arxiv.org/abs/1403.2705It is really hard to find a good description of Lambert's problem out there as actually used in orbital rendezvous.My impression is that most are trying to solve the Lambert Targeting Problem (LTP). i.e. given a fixed start time, a fixed end time, the angle between a start and end between two orbital bodies is known by their fixed orbits, the transfer time is fixed (because start/end are fixed) so calculate the deltaV required to make a rendezvous happen.

As I work through the problem I'm finding that if I completely stay in polar coordinates the targeting problem becomes trivial math.

I might be confused by the LTP math, but it appears that they didn't stay in polar coordinates which IMHO makes things far more complicated.

(That, and having the deltaV be the dependent variable instead of the independent variable).

@RadicalModerate helped me out with figuring out that all deltaV should be tangential is horribly incorrect for hyperbolic trajectories. Something else a simple Pork Chop plot can't do right.

The real answer for minimizing transit times while minimizing deltaV is...

Quote from: InterestedEngineer on 05/28/2024 03:38 am@RadicalModerate helped me out with figuring out that all deltaV should be tangential is horribly incorrect for hyperbolic trajectories. Something else a simple Pork Chop plot can't do right.I'm not aware of a Porkchop Plotter which makes that (surprising to me) assumption? Easy Porkchop certainly doesn't.Quote from: InterestedEngineer on 05/28/2024 03:38 amThe real answer for minimizing transit times while minimizing deltaV is......is to plot transit time vs delta-v (eg using a conventional plotter), and then feed that tradeoff curve forward into your mission architecture planning.There won't be just one universal solution that simultaneously minimizes both time and delta-v, because to reach a unique solution you effectively need some sort of "conversion ratio" between time and delta-v, and that tradeoff is going to be mission-specific.

The use cases I have are so bad for a pork chop plotter

1. I have 7km/sec of deltaV. Tell me how fast I can get to Mars. ...2. I want to get to Mars in 30 days. How much deltaV do I need?

3. I want to run a SEP craft with a certain mass flow rate and thrust to Mars. How long will it take? Pork chop plotters can't do continuous acceleration.

I don't want a pork chop plotter. I want a... mission planning tool that's almost a pork chop plotter?

Quote from: InterestedEngineer on 06/01/2024 12:27 am1. I have 7km/sec of deltaV. Tell me how fast I can get to Mars. ...2. I want to get to Mars in 30 days. How much deltaV do I need? Both of these seem solvable like I described earlier: a simple line graph with a single curve plotting delta-v vs transit time.However, for a dumb computer, you will still need to tell it the approximate start date and travel time of your journey, so it knows which conjunction (or even multi-revolution solution) you want to analyze. The easiest way to do that would be.... show the user a Porkchop Plot, and have them click on a point.Otherwise the computer will be "clever" and spit out the perfectly correct answer...... that's only valid for the 2177 Earth-Mars conjunction.

Quote from: InterestedEngineer on 06/01/2024 12:27 am3. I want to run a SEP craft with a certain mass flow rate and thrust to Mars. How long will it take? Pork chop plotters can't do continuous acceleration.Totally different bag of worms. Quote from: InterestedEngineer on 06/01/2024 12:27 amI don't want a pork chop plotter. I want a... mission planning tool that's almost a pork chop plotter?For the first two, would the graph like I described help?For the last one you'll need GMAT. More importantly, you need the custom non-public scripts that are used with GMAT for low-thrust optimization.

Quote from: Twark_Main on 06/01/2024 12:48 amQuote from: InterestedEngineer on 06/01/2024 12:27 am1. I have 7km/sec of deltaV. Tell me how fast I can get to Mars. ...2. I want to get to Mars in 30 days. How much deltaV do I need? Both of these seem solvable like I described earlier: a simple line graph with a single curve plotting delta-v vs transit time.However, for a dumb computer, you will still need to tell it the approximate start date and travel time of your journey, so it knows which conjunction (or even multi-revolution solution) you want to analyze. The easiest way to do that would be.... show the user a Porkchop Plot, and have them click on a point.Otherwise the computer will be "clever" and spit out the perfectly correct answer...... that's only valid for the 2177 Earth-Mars conjunction. Idealized is good enough. It is irrelevant whether it's +/- a couple of days or a 0.5 km/sec.

And Porkchops are terrible at hyperbolic trajectories. I've never seen one do one correctly.

They also don't spit out the vector for the deltaV. I can't even tell if they've optimized tangential and radial components.

Yes, but making the graph is the problem. At this point I'm far enough along I'll just make my own graphs.

Multi-variate optimization might be a bit of a hassle but it's doable, it's what neural net learning does all day long.

[...] I want a... mission planning tool [...]