Board index FlightGear Development Spaceflight

Space Shuttle

Discussion about development and usage of spacecraft

Re: Space Shuttle

Postby Hooray » Tue Mar 31, 2015 2:07 pm

but don't ever again lecture anyone else from the moral high ground how your repository respects aircraft maintainers, because we just have established that it really does not care.

you are giving a whole lot of weight to this repository by stating so - in fact, it isn't unlikely that others also commit "useful patches" to similar respositories, without meaning to violate any "etiquette". In fact, I have myself committed useful patches posted by folks like AndersG and ThorstenB to "public" topic branches on gitorious, and I didn't see anybody else make a fuss about that. Equally, I don't mind my own snippets posted on the forum/wiki to be committed/used by others - like you say, they shouldn't expect "support" from my side usually - but otherwise, I think it is only fair to work with the assumption that this is a GPL'ed project, and that there really is only a single "official" repository. And quite frankly, whenever people don't follow the rules of the official repository, they're weakening the status of their own repository - because, we as the community expect our work/contributions to be honored - which is why I think that the official repo(s) are actually being empowered by such actions
Please don't send support requests by PM, instead post your questions on the forum so that all users can contribute and benefit
Thanks & all the best,
Hooray
Help write next month's newsletter !
pui2canvas | MapStructure | Canvas Development | Programming resources
Hooray
 
Posts: 11782
Joined: Tue Mar 25, 2008 8:40 am

Re: Space Shuttle

Postby Johan G » Tue Mar 31, 2015 2:36 pm

@IAHM-COL: There seems to have been a misunderstanding here, and I would have to agree with Buckaroo:
Thorsten wrote in Mon Mar 30, 2015 5:28 pm:If you're asking whether you can put it onto a repo, I can't prevent you from doing it, but there's a reason I have not done it, and it's not lack of commit rights. What ends up on a repo should basically work for a number of use cases and be somewhat tested whereas this is not yet at this stage and I don't want to deal with 'X didn't work' reports at this point, I'm well aware of what doesn't work.

IAHM-COL wrote in Mon Mar 30, 2015 5:36 pm:I will mount it in FGMEMBERs so our FGDATA next users can fetch, and enjoy.
I Will leave a note there that you are not currently willing to receive issues and reports, so they won't be bothering you.

Buckaroo wrote in Tue Mar 31, 2015 3:06 am:...Thorsten's remarks appear to indicate that he believes the work is not yet ready to be shared in a public repository... I believe a little patience would have done more to honor his efforts.

I guess communication misses will happen from time to time when English might not be everyones first (or second) language... :roll: :wink:

While I understand that you want to share this, I can really understand Thorstens frustration. I have had similar experiences on the wiki with stuff on a subpage to my own page that was moved by someone else long before it was ready. I still am not sure if it even is possible to do what I intended to do with that stuff... :roll:
Low-level flying — It's all fun and games till someone looses an engine. (Paraphrased from a YouTube video)
Improving the Dassault Mirage F1 (Wiki, Forum, GitLab. Work in slow progress)
Johan G
Moderator
 
Posts: 5712
Joined: Fri Aug 06, 2010 5:33 pm
Location: Sweden
Callsign: SE-JG
IRC name: Johan_G
Version: 3.0.0
OS: Windows 7, 32 bit

Re: Space Shuttle

Postby IAHM-COL » Tue Mar 31, 2015 3:37 pm

Thanks for your comments (@ALL)

I am still trying to understand each of your points.

@thorsten:
I do not think you should be of bigger concern that a lot of issues or comments will be generated by the FGMEMBERs repository. I hardly believe any at all. The fact that your pre-release is available as a zip (on the first of these thread), and a repo (in FGMEMBERS) does not alter any responsibility or property you feel entitled to the SpaceShuttle.
I am re-reading your comments again to see what are your particular points about moral ground and legal ground on the issue.

Whether you agree with me or with Ludovic about what's proper or improper respecting Other aircraft maintainer code in a subversion repository is a matter of deep importance. But I quite don't get if you agree or disagree with me. Keeping in mind, that one thing is the subversion repository, other different topic is "yet another git" repository.

On the essential of this difference is that I so persistently deffended my proposal to dev-cores, probably a little too much.

@Buck
Thanks for the comments too. But remember that it has been established and decided so by the core developers that the official repository for FG aircraft, as Hooray point out, is FGAddon. More importantly, no efforts of synchronization are taken place. Althought, I do rebase all commits and new aircraft, etc in FGMEMBERs, the order that changes need to occur in FGAddon first, is not a guarantee. Not that every commit in FGMEMBERS also exist officially

An aircraft in very crude/early development, and or in unsupported or unwarranted state can exist in FGMEMBERs and can be initialized or deinitialized per user. The FGAddon repository is to my understanding a collection of very mature, tested and "approved" aircraft, with a warranty by official maintainers. That makes quite a difference into when the SpaceShuttle can be integrated, and thus I understand that is what @Thorsten reffers too, when he says that his Shuttle is still not up to a repository.

When Thorsten details his work and commits to SVN, no major change but an upstream redirection occurs for the FGMEMBERs area (plus off course new updates being pushed in).
In the mean time, users of FGMEMBERS and FGDATAnext with submodules can test, enjoy, fork and develop Thorsten work concomitantly with the pre-release and any other future pre-release he makes: Unless these are not covered under a GPL clause.

@Hooray
I am not sure what your point is, but sounds reasonable all together.

@JohanG
Yes, I think communication is an art lost here. But I do not quite know yet if its an English issue all together.

Again,
Thanks all for your comments, and more specially, at Thorsten for bringing us the "space age" back to FG.

Best Regards,
IHCOL
If we gave everybody in the World free software today, but we failed to teach them about the four freedoms, five years from now, would they still have it? Probably not, because if they don’t recognise their freedoms, they’ll let their freedoms fall
User avatar
IAHM-COL
Retired
 
Posts: 4064
Joined: Wed Aug 08, 2012 5:40 pm
Location: Homey, NV (KXTA) - U.S.A
Callsign: HK-424D or ICAO4243
Version: 3.7-git
OS: Linux

Re: Flightgear space program

Postby jarl.arntzen » Wed Apr 01, 2015 1:43 pm

Thorsten wrote in Wed Mar 25, 2015 10:00 am:

Image

SRB separation and switch to EarthView as rendering engine - we're at about 650.000 ft, on the long race towards orbital velocity. The vessel is still completely maneuverable by thrust vectoring.


This looks completely fantastic in my very humble opinion. Both shuttle and scenery is far above and beyond what I'd thought would be realistically achievable in FG.

I've often thought it's interesting to watch the launch of any rocket as you can literally see the effects of atmospheric pressure on the shape, size and colouring of exhaust plume as the vessel ascends into thinner atmosphere as can be seen in this footage of an Atlas V launch in 2010. The physical presence of the atmosphere is evident. It's not some invisible void but actual, heavy medium that shapes the roaring column of fire at the start into a narrow focused beam and then later in flight eases off the pressure to allow the exhaust to escape in a wider fan.




https://www.youtube.com/watch?v=gtrB9bELGSY
  1. @Launch +0:54 "We're approaching Mach 1"
    Image

  2. @Launch +1:57 "We're 12 miles in altitude 11 miles down range, travelling at 2300 mph"
    Image
  3. @Launch +2:15 Control@ 2:25 "We're at 50% of lift-off weight, continues to operate at 95% thrust"
    Image
  4. @Launch +2:30 Exhaust plume is almost invisible and appears 4-5x wider than the vessel.
    Image

  5. @Launch +3:15 Control says "38 miles in altitude, 83 miles down range, travelling at 6600 mph. Vehicle now weights 25% of its lift-off weight "

It would be interesting to see effects on the exhaust plume as a function of local atmospheric pressure. I'm pretty sure it hasn't been done before, anywhere. :)
Frequent Flyer. Occasional Lander.
jarl.arntzen
 
Posts: 106
Joined: Thu Jan 03, 2013 9:43 pm
IRC name: Jarl Arntzen
Version: 2017.1.1
OS: Ubuntu 14.04

Re: Space Shuttle

Postby Thorsten » Thu Apr 02, 2015 1:35 pm

I struck gold for the aerodynamical phase modeling - I found a full, well-tested 2d parametrization of wind-tunnel data, giving C_L and C_D in the range from Mach 0.6 to Mach 8 for all alpha - I think that's way better than most planes do :-)

I've been testing it doing TAEM approaches and comparing with the published numbers.
Thorsten
 
Posts: 11604
Joined: Mon Nov 02, 2009 8:33 am

Re: Space Shuttle

Postby Johan G » Thu Apr 02, 2015 2:43 pm

Thorsten wrote in Thu Apr 02, 2015 1:35 pm:I struck gold for the aerodynamical phase modeling...

Wonderful! :D
Low-level flying — It's all fun and games till someone looses an engine. (Paraphrased from a YouTube video)
Improving the Dassault Mirage F1 (Wiki, Forum, GitLab. Work in slow progress)
Johan G
Moderator
 
Posts: 5712
Joined: Fri Aug 06, 2010 5:33 pm
Location: Sweden
Callsign: SE-JG
IRC name: Johan_G
Version: 3.0.0
OS: Windows 7, 32 bit

Re: Space Shuttle

Postby Thorsten » Fri Apr 03, 2015 7:52 am

I'm actually quite happy with the aerodynamics. I have a diagram of position, altitude and velocity of Columbia coming in after her first flight, and I can basically reproduce the pattern. So - here's a Terminal Area Energy Management (TAEM) stage flown into Kona - Hawaii (this has a nice 11.000 ft runway).

TAEM starts at 82.000 ft with about Mach 2.5 - we're pointed straight into Kona and will overfly it before turning around.

Image

On the first stretch, the task is to bleed off the remaining energy - the 60 miles to Kona we spend on a shallow glideslope (about 5 deg), going subsonic at about 49.000 ft just about overflying the landing site.

Image

Internal view of the same scene - still pretty high, huh? But the whole experience doesn't last very long, the descent rate from this point on is something like 10.000 ft/min

Image

Turning into the heading alignment cylinder - basically we corcscrew down the surface of an imaginary cylinder to emerge at the desired landing heading - all the while dropping with the 10.000 ft/sec:

Image

Coming out of the turn, we are considerably lower (cylinder is entered above 32.000 ft, we come out at a good 10.000) and we go directly into final approach.

Image

In the event, I came in low, but the whole approach is designed to offer lots of safety reserves, so no problem. Steep descent (should be 15-17 deg glideslope, but I came in low) into Kona, doing last corrections.

Image

Wheels down, speedbrake and drag chute deployed, braking hard:

Image

Wheels stop - an unusual visitor to Kona airport:

Image

(any 3d modeler wants to fix the issues - I basically can't do any 3d modeling - we need a gear and thruster pods for the external - and of course a 3d cockpit for the internal views... :-) )
Last edited by Thorsten on Fri Apr 03, 2015 7:58 am, edited 1 time in total.
Thorsten
 
Posts: 11604
Joined: Mon Nov 02, 2009 8:33 am

Re: Space Shuttle

Postby Thorsten » Fri Apr 03, 2015 7:53 am

It would be interesting to see effects on the exhaust plume as a function of local atmospheric pressure. I'm pretty sure it hasn't been done before, anywhere


Comceptually this would be trivial, just a setting for the particle system. The problem is that the system goes astray at high velocities, the numerical issues are just too great (which is why the RCS thrusters don't use particles in orbit - they ended up all over the place). Needs to be tried.
Thorsten
 
Posts: 11604
Joined: Mon Nov 02, 2009 8:33 am

Re: Space Shuttle

Postby Pakistan-1 » Fri Apr 03, 2015 10:32 am

Are there any re-entry effects in FG?
User avatar
Pakistan-1
 
Posts: 499
Joined: Tue Jun 18, 2013 2:49 am
Location: Hong Kong
Callsign: DocDMG,PK1,MIA2020
Version: 3.7
OS: Windows 10

Re: Space Shuttle

Postby Thorsten » Fri Apr 03, 2015 12:00 pm

Like what? Plasma, heat shield glow or so you have to put in, nose and wing edge temperature you have to compute.

But it does the entry trajectory like a charm - you can control deceleration /sinkrate and steer a course pretty okay. On the first go, I had just too little elevator action, and I'm trying to find out why precisely.
Thorsten
 
Posts: 11604
Joined: Mon Nov 02, 2009 8:33 am

Re: Space Shuttle

Postby Johan G » Fri Apr 03, 2015 3:55 pm

That looks really promising. :)
Low-level flying — It's all fun and games till someone looses an engine. (Paraphrased from a YouTube video)
Improving the Dassault Mirage F1 (Wiki, Forum, GitLab. Work in slow progress)
Johan G
Moderator
 
Posts: 5712
Joined: Fri Aug 06, 2010 5:33 pm
Location: Sweden
Callsign: SE-JG
IRC name: Johan_G
Version: 3.0.0
OS: Windows 7, 32 bit

Re: Space Shuttle

Postby wlbragg » Fri Apr 03, 2015 7:25 pm

We need to get a crew together and start on all the model animations and effects! :)
Kansas(2-27-15)/Ohio/Midwest scenery development.
KEQA (2-27-15), 3AU, KRCP Airport Layout
Intel i5 3570K AMDRX480
User avatar
wlbragg
 
Posts: 5525
Joined: Sat Aug 25, 2012 11:31 pm
Location: Kansas (Tornado Alley), USA
Callsign: WC2020
Version: next
OS: Win10/Linux/AMDRX480

Re: Space Shuttle

Postby Thorsten » Sat Apr 04, 2015 11:25 am

After a few tries, I *think* I got the re-entry dynamics under control - now I've got the irreversible 40 deg pitch angle in, and I can nicely manage my trajectory by high-bank angle S-turns - just the handover from thrusters to airfoils needs to be written automatically...
Thorsten
 
Posts: 11604
Joined: Mon Nov 02, 2009 8:33 am

Re: Space Shuttle

Postby Thorsten » Mon Apr 06, 2015 6:36 am

Enjoy the latest version from FGAddon.

* now uses the more realistic SRB definitions from the JSBSim repo
* a full RCS translation mode
* realistic handover of controls from RCS to aero during the initial entry phase
* (rough) modeling of thermal load on the nose cone during ascent and entry
* phase-specific HUD information
* tested for ascent, orbital maneuvering, de-orbit, entry and approach, compares reasonably with NASA-published procedures
Thorsten
 
Posts: 11604
Joined: Mon Nov 02, 2009 8:33 am

Re: Space Shuttle

Postby IAHM-COL » Mon Apr 06, 2015 3:24 pm

@Thorsten

Thanks :D

Now FGMEMBERs rebased and sat the repo downstreams of SVN FGAddon

Great Work :)

Best,
IH-COL
If we gave everybody in the World free software today, but we failed to teach them about the four freedoms, five years from now, would they still have it? Probably not, because if they don’t recognise their freedoms, they’ll let their freedoms fall
User avatar
IAHM-COL
Retired
 
Posts: 4064
Joined: Wed Aug 08, 2012 5:40 pm
Location: Homey, NV (KXTA) - U.S.A
Callsign: HK-424D or ICAO4243
Version: 3.7-git
OS: Linux

PreviousNext

Return to Spaceflight

Who is online

Users browsing this forum: Vinny002 and 2 guests