42 - Spacecraft Simulation | Hacker News Reader

42 - Spacecraft Simulation

github.com

81 pointsStevvo10 comments

For my novel, I was struggling to find rocket simulators that allowed setting an initial velocity for the rocket. Most of them presume a starting velocity of 0. So, tangentially related, here is my calculator that allows users to provide an initial speed for the rocket before burning its onboard fuel:

https://autonoma.ca/calculators/rocket/payload/

Source file containing most of the delta-v calculations:

https://autonoma.ca/calculators/rocket/payload/Rocket.js

Being able to see all the TeX equations rendered with KaTeX on a single page is quite convenient.

Can I see it in action?

Would love to see it model the optimal suicide burn from Lunar Lander http://moonlander.seb.ly/

https://www.youtube.com/watch?v=Xg5cevIOnHk

The graphics are surprisingly good; maybe better than stock KSP.

A lot of 42's usage comes from it's proximity to NASA Goddard's cFS, the most widely used (and in my opinion, best) open-source flight software framework out there. However, many space companies move towards using their own simulation stack, especially when it comes to using the models for driving hardware-in-the-loop (HITL/HIL) simulations with things like fault injection for mission operations drills.

Other open-source solutions for this include:

* Nyx - https://github.com/nyx-space/nyx

* Basilisk - https://github.com/AVSLab/basilisk

This is really cool, does anyone know how it compares to NASA Trick? https://github.com/nasa/trick

It’s somehow a shame that this has have a core written in C, but there really isn’t an alternative. It’s a really neat project! It looks like its designed to be used from Matlab or Julia, which is a fascinating pairing.

It’s somehow a shame that this has have a core written in C

can you elaborate? why would that be a shame?

I suppose because Matlab is a language designed for math, compared to C which is designed as a low level systems language. Julia would be more or less an open source equivalent of Matlab.

It seems that the code was translated from Fortan to C, however which makes sort of explains it since it would be fairly trivial to translate from Fortran to C.

Code written in C with a lot of math in it would become quite convoluted and tedious to work with in comparison. Apart from that you probably have a lot of useful tooling with Julia and Matlab.

So if anyone wants to start working on rocket science using computer programming, Matlab or Julia would be worth looking into.

Fairly often, I find myself writing in C when I would rather be writing Julia, because Julia just isn’t quite there yet. I figured that the author was probably in a similar conundrum, judging by the mix of languages in the repository. I suspect I did not communicate this sentiment clearly haha

The models it runs were originally written in FORTRAN. They were ported to C for convenience.

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