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Re: Space Shuttle

Postby Thorsten » Mon Dec 21, 2015 10:41 am

That's neat - combined with switching off what we don't need (I guess we need to run most AP tags only when FCS is actually in AUTO mode) we should be able to slim it down quite a bit.
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Re: Space Shuttle

Postby Hooray » Mon Dec 21, 2015 7:58 pm

Thorsten wrote in Mon Dec 21, 2015 6:23 am:Though we do have several advantages - first, JSBSim and large aero databases from NASA combine into realistic flight and orbital dynamics quickly. Second, the way canvas allows screens by compositing elements means rapid advancement - I don't have all common elements to all screens going for instance, but it's a piece of cake just adding something to the common section.

Well, at the end of the day, we have a really large toolkit to get things done - JSBSim tags, property rules, Nasal, configurable effects and shaders,... so lots of things can be done rapdily without the need to learn how to code it in detail.


That is true, there are a number of highly configurable systems in place, which would otherwise require tons of C++ code to be written, especially the MFD stuff would require quite a bit of OSG/OpenGL knowledge if it wasn't Canvas based, i.e. using underlying primitives in the form of osgText, OpenVG paths and raster images - looking at the fate of other hard-coded ODGauge instruments in FlightGear, it really seems that Canvas is a huge technology enabler in comparison to the more traditional route.

The degree of Nasal used/needed to implement some features may admittedly be a little unfortunate for those wanting to run such systems in standalone mode.

Anyway, looking at the 6-year timespan, and the fact that the spaceshuttle simulator is a commercial project, it is pretty fascinating to see how much progress has been made over the course of ~6 months by a handful of volunteers in their spare time.
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Re: Space Shuttle

Postby Thorsten » Tue Dec 22, 2015 6:09 pm

Look - it's an Aurora Borealis display outside:

Image

(I've been reading up some on what actually makes the different colors and at what altitudes you're expected to see it, and compared with actual photographs from the Shuttle, and it's fairly authentic now... I guess I now need to write an aurora manager in property rules to make it all scale with the solar wind etc...)

In other matters:

@wlbragg: Do you think you could model some sort of 'shell' around the cockpit? We could make it transparent normally (or use <select> to make it vanish) and render the flames of re-entry onto it when the Shuttle gets hot - I'm afraid we're never going to see the particle system from the windows, but the effect of the plasma actually is very visible in reality, so we ought to model it.
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Re: Space Shuttle

Postby wlbragg » Tue Dec 22, 2015 7:56 pm

Can you point me to something or explain to get an idea of the basic shape we need?
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Re: Space Shuttle

Postby Thorsten » Wed Dec 23, 2015 6:14 am

Doesn't really matter, it should just be something transparent that must be seen when looking through the windows regardless of angle. I just need a continuous surface a shader can project onto which shouldn't have clipping artifacts with other surfaces and shouldn't be too far away.

Think of it as if we'd want to install a screen in a simulator to project onto - we have the cockpit, now we need the projected reality :-)
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Re: Space Shuttle

Postby wlbragg » Wed Dec 23, 2015 7:08 am

OK I get it, it's for a visual from inside the shuttle looking out the windows.

It may be after Christmas before I can get to it, My wife took my computer away until I do my chores. :lol:
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Re: Space Shuttle

Postby wlbragg » Wed Dec 23, 2015 8:32 pm

OK, I found a moment to make the "Plasma_Screen" object, I misnamed it in the commit message. Let me know if you need any modifications to it.
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Re: Space Shuttle

Postby Thorsten » Mon Jan 11, 2016 4:25 pm

I'm currently flight-testing the Shuttle and will tag a milestone as soon as it checks out, which Richard has agreed to push to FGAddon then.

I've successfully flown an orbital insertion and an entry interface to touchdown with recovery from a low energy condition, so the basic flight dynamics checks out and the guidance works fine. What struck me is that one had to change OPS to 305 at TAEM interface manually, but I think that's realistic. In any case, the FCS holds the Shuttle nice and smooth even if you let go of controls, so that's not an issue.

I'll proceed to test some orbital functionality tomorrow and then do the tag. If you're aware of any critical issues that prevent operations otherwise, please let me know basically now.
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Re: Space Shuttle

Postby legoboyvdlp » Mon Jan 11, 2016 6:15 pm

Excellent, Thorsten. I'm very happy to hear that.
(Well, obviously, I don't know how you'd recover from a low energy condition, since there are no 'entry' engines.)
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Re: Space Shuttle

Postby Thorsten » Mon Jan 11, 2016 6:22 pm

You optimize the glidepath - you don't do high bank maneuvers and roll reversals and select a straight-in TAEM pattern and leave the speedbrake in. There's ample of margin to recover from being below the nominal entry trajectory.
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Re: Space Shuttle

Postby Thorsten » Tue Jan 12, 2016 8:23 am

A milestone-5 is now tagged in which I have tested a lot of operations and ironed out some four bugs.
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Re: Space Shuttle

Postby bugman » Tue Jan 12, 2016 11:39 am

I just noticed that James' work on improving time warping in FlightGear has had a noticeable effect on the shuttle. If you drop the external tank in orbit then accelerate time, there are no longer any strange effects of the tank shooting off like a ballistic missile. Both the shuttle and external tank are affected by warped time in the same way.

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Re: Space Shuttle

Postby Thorsten » Tue Jan 12, 2016 12:42 pm

I suspect it might rather be because I adapted the code to take the acceleration factor into account, but one never knows :-)
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Re: Space Shuttle

Postby bugman » Tue Jan 12, 2016 12:53 pm

Oh, I must have missed it. Maybe it would be good when pushing a huge pile of squashed commits as one to FGAddon, such as r789, to include the "git log --oneline" output in the body of the svn commit message? As well as maybe a link to the upstream repository branch. It would really help for following the developments.

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Re: Space Shuttle

Postby Thorsten » Fri Feb 05, 2016 5:55 pm

Been testing an AP addition for automatic launch. I get halfway already - Mach 10 at 140 km altitude, vertical velocity captured, inclination acquired and locked. It's a nice problem, because there's quite many layers between the engine gimbal angles and the altitude error. Basically there needs to be lots of advance planning till you actually get into a situation in which you can really control altitude, because in the initial ballistic phase it takes a minute till any gimbal angle really influences anything.

But it turns out to be all more or less doable, so in the future you might be able to use the pushbuttons on the panel during launch.

I also need to write a computer for the launch course as a function of desired inclination...
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