[WEB] Atmospheric Entry & Aerobraking Timing calculator.

[cfe316]

Atmospheric Entry & Aerobraking Timing Calculator

If you are heading toward a planet and will intersect the atmosphere, it's important to know what will happen. Will you hit the atmosphere low enough to (crash) land or just do aerobraking? If aerobraking, will you be captured into an elliptical orbit or still be on a hyperbolic orbit? How long will you be in the atmosphere for, or (approximately) when will landing occur? This calculator can help.

http://cfe316.github.io/ksp_atm_entry/

This calculator is primarily meant for use with mods like RemoteTech where craft cannot be controlled instantly; rather, burns and actions must be pre-programmed, so timing is important.

Given an initial altitude, periapsis, and velocity (and body that you're orbiting), it will compute the outcome.

This calculator is a descendent of Alterbaron's Aerobraking Calculator http://alterbaron.github.io/ksp_aerocalc/ and borrows the interface and integrator, but is somewhat different. Alterbaron's calculator solves for an aerobraking periapsis for a desired apoapsis and tells you how to burn. This calculator only predicts what will happen, and handles landing and escaping rather than only aerobraking.

While the Trajectories mod displays landing or aerobraking trajectories, I don't believe it offers this sort of timing information. (I don't have it installed so please correct me...)

For Best Results

Don't enter the values when you're right at apoapsis; the maths (and your velocities) have limited precision there. Best wait till a few degrees afterward.

To use this calculator when your ship is headed up toward apoapsis, add twice your 'time to apoapsis' from the in-game orbit display to the results.

(Edit April 23rd: I've fixed the code and prograde vs retrograde orbits now work correctly: previously, they had been switched.)

The 'time to (and altitude at) 250m/s' are currently using the orbital velocity, not the surface velocity. Since the planet's surface is moving in the orbital frame, you should actually be going slower than 250m/s at the stated time. Since Jool's 'surface' moves faster than that, it gives nonsense answers, but also trying to land on Jool is a bad idea. I'm planning to fix this to track the surface velocity instead (as one would expect).

Remember that terrain height can be non-negligible. The 'Time to 0m' assumes no terrain.

Remember not to extend solar panels until after you're sure the chutes have deployed fully, else they can break off.

Edited April 23, 2015 by cfe316