Stargazer: program for inteplanetary transfer calculation

[maisvendoo]

Hello!

I want introduce the first beta-version of the program for interplanetary transfer trajectory calculation. It can:

1. Orbital position of the panet or moon for any time moment

2. Elliptic (parabolic and hyperbolic for external planets or moons) transfer trajectory between planets or two moons

3. Eject manuever from departure planet/moon from low orbit

4. Low orbit parameters (inclination, longtitude of ascending node, argument of periapsis)

Today all calculation are executed for celestial bodies with same reference body

Screenshot

You can dowload this utility here

Source code awayable at GitHub

Short manual

1. Change depature and arrival celestial bodies. Warning: both bodies must have same reference body (from Kerbin to Duna, or from Mun to Minmus, for example). Transfer from planet to it's moon is imposible now.

2. Change time interval for transfer window search.

3. Set low orbit altitude near departure body.

4. Click "Search" button.

5. Set Psi angle for reach minimal delta V. You can increment and decrement Psi by "+" and "-" buttons with custom step. You trajectory is recalculated automaticaly

Scheme of interpanetary trajectory calculation

Green plane - departure planet orbit

Yellow plane - arrival planet orbit

Red plane - transfer orbit

Lambda_err - error of ecliptic longtiture at arrival time. If transref orbit is good, Lambda_err = 0

vK - departure planet velocity veclor

vA - transfer trajectory velocity vector at departure time

v_rho - departure body SOI escape velocity

It is only beta-version for first testing. Today it is a external program, but it will be developed as mode for KSP.

P.S.: Sorry my very bad english

Edited October 15, 2015 by maisvendoo

[maisvendoo]

Today I can introduce new version of Strargazer interplanetary calculator.

Changes in version 0.1.0

1. Greek letters in user interface

2. Calculation of launch data and launch azimuth for assent to low orbit. You can set coordinates of launchpad (KSC launchpad as default)

3. Fixed some small bugs in user interface and calculation algorithm

You can download it here

Screenshot

Edited October 25, 2015 by maisvendoo

[Wcmille]

Will this tool work with any starting eccentricity and inclination, or do you need to have circular orbit, with starting inclination of 0? If not, may I ask how do you solve for that?

[skYman]

Is this hard-coded or do you pull the bodies-info off the game somehow?

i.e. would this work with modded installs?

[maisvendoo]

On 11.01.2016 at 8:01 AM, Wcmille said:

Will this tool work with any starting eccentricity and inclination, or do you need to have circular orbit, with starting inclination of 0? If not, may I ask how do you solve for that?

Which orbit you mean?

On 13.01.2016 at 6:40 AM, skYman said:

Is this hard-coded or do you pull the bodies-info off the game somehow?

i.e. would this work with modded installs?

All bodies data are in file cfg/kerbal.xml. You can change it, if you want manualy. This file is generated from game by my small plugin, because there are no config file with bodies data in game. 

[White Owl]

This looks like the ideal tool for finding transfer windows in the Harder Solar System mod.

[maisvendoo]

5 hours ago, White Owl said:

This looks like the ideal tool for finding transfer windows in the Harder Solar System mod.

This is a good idea, it'll work with Solar System, if kerbal.xml to edit. But this program work with Kerbal's calendar only: 6 hours in day and 426 days in year are hard-coded in current version. 

This code

Calendar.cs

public class KCalendar
    {
        public const int Days = 426;
        public const int Hours = 6;
        public const int Mins = 60;
        public const int Secs = 60;

        public static double  date_to_sec(int year, int day, int hour, int min, int sec)
        {
            return 9201600.0 * (year - 1) + 21600.0 * (day - 1) + 3600.0 * hour + 60.0 * min + sec;
        }

        public static void sec_to_date(double t, ref KDate date)
        {
            int sYear = Days * Hours * Mins * Secs;
            int sDay = Hours * Mins * Secs;
            int sHour = Mins * Secs;
            int sMin = Secs;

            date.year = Convert.ToInt32(Math.Truncate(t / sYear)) + 1;
            date.day = Convert.ToInt32(Math.Truncate( (t - (date.year-1)*sYear) / sDay)) + 1;
            date.hour = Convert.ToInt32(Math.Truncate((t - (date.year - 1) * sYear - (date.day - 1) * sDay) / sHour));
            date.min = Convert.ToInt32(Math.Truncate((t - (date.year - 1) * sYear - (date.day - 1) * sDay - date.hour * sHour) / sMin));
            date.sec = Convert.ToInt32(Math.Truncate(t - (date.year - 1) * sYear - (date.day - 1) * sDay - date.hour * sHour - date.min * sMin));
        }

        public static void DeltaDate(double t, ref KDate date)
        {
            int sYear = Days * Hours * Mins * Secs;
            int sDay = Hours * Mins * Secs;
            int sHour = Mins * Secs;
            int sMin = Secs;

            date.year = Convert.ToInt32(Math.Truncate(t / sYear));
            date.day = Convert.ToInt32(Math.Truncate((t - (date.year) * sYear) / sDay));
            date.hour = Convert.ToInt32(Math.Truncate((t - (date.year) * sYear - (date.day ) * sDay) / sHour));
            date.min = Convert.ToInt32(Math.Truncate((t - (date.year) * sYear - (date.day) * sDay - date.hour * sHour) / sMin));
            date.sec = Convert.ToInt32(Math.Truncate(t - (date.year) * sYear - (date.day) * sDay - date.hour * sHour - date.min * sMin));
        }
    }

must be changed to Solar system transfer calculations

Edited January 23, 2016 by maisvendoo

[White Owl]

Okay, thank you very much.