OHM SolarSailEx

Wishbone

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Digging at NTRS (NASA Technical reports).
Looked up the formulae for guidance (the code was written in Fortran in 1977, uses RK4 to get to the point), attitude control laws, and sail thermal constraints. Some of the formulas will be available in the source as soon as I upload Precession MFD to O-H. It already has instant killrot (cheating!), now I want to forego the difficulties of attitude control/stabilization and implement (via MFD) instant selection of cone and clock angles. Would be nice to organize a small Earth-to-the-Moon challenge...
 

Wishbone

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Solar bug

Here's the screenie of the NaN bug I mentioned earlier. The file was quicksaved when all rotation was nulled via Scenario editor.
 

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BrianJ

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Digging at NTRS (NASA Technical reports).
Looked up the formulae for guidance (the code was written in Fortran in 1977, uses RK4 to get to the point), attitude control laws, and sail thermal constraints. Some of the formulas will be available in the source as soon as I upload Precession MFD to O-H. It already has instant killrot (cheating!), now I want to forego the difficulties of attitude control/stabilization and implement (via MFD) instant selection of cone and clock angles. Would be nice to organize a small Earth-to-the-Moon challenge...
Sounds cool. I'll have to take a look at your "PrecessionMFD" :)

Here's the screenie of the NaN bug I mentioned earlier. The file was quicksaved when all rotation was nulled via Scenario editor.

Thanks, I'll see if I can figure where the bug is!
 

BrianJ

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Hmmm, I can't reproduce the "NaN" bug - anyone else having the same problem?
 

Aldrasio

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This is so fun to fly! If there were any attitude autopilots, this would be perfect.
 

Wishbone

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Shameless plug: (work in progress, but you can use RShift numpad keys to "cheat" with attitude control) - [ame="http://www.orbithangar.com/searchid.php?ID=4889"]Precession MFD[/ame]
 

BrianJ

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This is so fun to fly! If there were any attitude autopilots, this would be perfect.
With the help of Wishbone's "PrecessionMFD", I am working on some auto-attitude functions - although the sail attitude is set mathematically (doesn't use the "paddles") - so that might be considered cheating! ;)
But at least they work at high-time accelerations.

(At the moment I'm more interested in possible trajectories, rather than realistic attitude control.)


So far I've implemented:
Max. Thrust along Prograde Vector
Max. Thrust along Retrograde Vector
Sail +Z axis along Prograde Vector
Sail +Z axis normal to Solar Flux vector (no thrust)
Escape Strategy (combination of above modes + sun angle offsets)
- for boosting orbit from low-planet-orbit while maintaining Perigee alt.

I'm going to see if I can make a "Capture Strategy" mode (for orbit insertion) and fix a few other things, then I'll upload the next version :)

Cheers,
Brian
 

BrianJ

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Hi,
just a little update, now available on OrbitHangar.

Includes auto-attitude modes (set mathematically by the sail module):
max-prograde accel, max-retrograde accel, hold flux-relative attitude, hold velocity-relative attitude, "escape" strategy.

Also, parameters such as sail area, sail albedo, paddle area, etc. can be set in the .cfg file.

See Doc for more details.

*******************

The "Escape Strategy" mode works OK, but certainly not optimal.

I never could figure out a "Capture Strategy" mode - it all depends how you are approaching the planet.

I managed to get to Mars from Earth in about 1 year, then spent 1.5 years chasing it around trying to get into a lower orbit(not so easy) ;-)

Max. velocity after 0.2 AU pass of the Sun, 130km/s !

Cheers,
Brian
 

Wishbone

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Brian, you're way too modest. Would you please re-set the date of your brilliant add-on to Jan 21, 2011, so that more people could see it in the right sidebar at OHM?
 

BrianJ

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Ah, you are too kind, sir ;-) 'Tis done.
 

Wishbone

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Notes from actual runs: looks fine under acceleration. But. The sail is too dim, and doesn't at all look a shining mirror. Maybe I'm using default settings... BTW, does it use the values of reflectivity etc. from the config for actual visual representation?
 

BrianJ

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Notes from actual runs: looks fine under acceleration. But. The sail is too dim, and doesn't at all look a shining mirror. Maybe I'm using default settings... BTW, does it use the values of reflectivity etc. from the config for actual visual representation?
Thanks for the report. The values in the config file only affect the force/thrust calculations for the sail/paddles - they don't affect the visuals. I really haven't paid much attention to the original visuals/mesh. Might be a nice idea for a future update.

I'll have to have a look at your "Equilibrium Temperature" code in PrecessionMFD, too, as a constraint on getting to close too the Sun...."Mission Failed: You Have Vapourised!" kind of thing.

I'm hoping someone will be tempted into making some kind of navigation MFD for solar sailing - otherwise I'll have to try to make one, which will be quite a challenge for my limited programming skills!! Any takers??

All the best,
Brian
 

BrianJ

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Now updated for Orbiter2016, v.200611 on OrbitHangar.
 

asbjos

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Just a tip: the controls (numpad) doesn't work for people without a numeric keypad (like me). I've used keymap.cfg to reconfigure them to other keys, but you are specifically checking the numpad keys, which I'm then unable to control.

I would recommend instead creating dummy RCS thrusters (thrusters with zero thrust and zero ISP, must be connected to some propellant source, but will not draw any propellant), map those to the default thruster groups (CreateThrusterGroup), and instead monitor the thruster level on those, and map that level to the paddle deflections (GetThrusterGroupLevel).

This also goes for your Starship Mk.1 addon, by the way. :)
 

BrianJ

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Just a tip: the controls (numpad) doesn't work for people without a numeric keypad (like me). I've used keymap.cfg to reconfigure them to other keys, but you are specifically checking the numpad keys, which I'm then unable to control.

I would recommend instead creating dummy RCS thrusters (thrusters with zero thrust and zero ISP, must be connected to some propellant source, but will not draw any propellant), map those to the default thruster groups (CreateThrusterGroup), and instead monitor the thruster level on those, and map that level to the paddle deflections (GetThrusterGroupLevel).

This also goes for your Starship Mk.1 addon, by the way. :)
I just recompiled this for compatibility with Orbiter2016, by special request ;-) Not really planning on doing much else with it. People are free to adapt the code as needed. I guess on Starship you could use a joystick.
Cheers,
Brian
 

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I just recompiled this for compatibility with Orbiter2016, by special request ;-) Not really planning on doing much else with it. People are free to adapt the code as needed. I guess on Starship you could use a joystick.
Cheers,
Brian

I have an Toshiba laptop with Windows 7 on it! I use a Logitech 101-Key Keyboard plugged into my USB port! At $10.00 at Walmart an excellent buy! Real men do land airplanes with a keyboard! :thumbup: I'm downloading a copy of Solar Sail EX ASAP!

Thanks, Brian!

Christopher Tarana
 
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