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Grob 103 sailplane available for test flying!

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Grob 103 sailplane available for test flying!

Postby gliderace » Mon Nov 26, 2007 7:01 pm

I am working on a Grob 103 sailplane, and have a ZIP available for download at http://www.coldwaterdesign.com/simaircraft/grob103.zip.

If anyone is interested, and has the time, I would appreciate feedback.

I am a Grob 103 pilot, and have had one modeled for X-Plane for quite some time now; this is my first foray into FG, however, and much of what I created for X-Plane is ported over to this system.

I have three areas of interest that I would appreciate any help with:

1) Visually, I am still working on it...it is getting there, but the 'right' side seems to have some unusual shading (I tried making surfaces two-sided via Blender in UVFaceSelect, and still have some strangeness). This is best seen from the cockpit, looking to the right wing and then craning around to look at the left wing. The cockpit is 3D, and with minimal instrumentation for now.

2) The flight model uses JSBsim...I would like to use YASIM, and tried that at first and never got any forward motion...literally. The sailplane just would not respond. Does YASIM not allow sailplanes? I find that hard to believe and think it was my own ineptitude with the YASIM xml. Does anyone prefer YASIM over JSBsim? With JSB, I can use the correct Eppler 603 airfoil Cl data per degree, it seems, which is nice...

3) Does anyone have a variometer for sailplanes? Note that I do not have one, here. The ASI utilizes a photo from the Grob that I fly, and I believe I have the speed ranges worked out on its unique nautilus dial. Any help with a vario is appreciated.

Thank you all in advance,

Sonny
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Postby ajm » Mon Nov 26, 2007 8:32 pm

Hi Sonny, very nice to see some more interest in gliding and FlightGear :-) (You've seen the the earlier thread on here about gliding - with some nice add-on scenery including a gliding club?)

I had a quick flight with your glider, and can see that you've managed to get over a lot of the initial difficulties already (making 3d instruments and placing them in the cockpit, for example...)

I presume, from what you've said, that you're using FG 0.9.10. In that release, YASim didn't really support glider models, but the excellent news is that in the imminent release (0.9.11) it not only supports gliders, but winch launches and aerotows (including aerotows over the Internet!)

Unfortunately JSBSim doesn't yet support these capabilities, and though support is "planned" YASim is probably the glider FDM of choice for now. There's nothing to prevent you having both a yasim and jsbsim version of your glider anyway, and if you have good numbers for the JSBSim config then it would be a nice additional option for in-air starts.

There are also two new gliders since 0.9.10, the Ask21 and the Bocian/SZD-9. They both have a simple audio variometer, but I'm certain we can do much better with input from someone who has more gliding experience (I only have a few Bocian flights to my name). The Bocian flight model also needs a good bit of tuning, but the instrumentation is quite complete, even if the rest of the cockpit and the exterior requires a bit of work still.

Some quick screenshots are here:

Aerotow with Bocian pilot in the UK and cub in Germany...
http://www.adeptopensource.co.uk/person ... d_tow2.jpg

The still slightly rough Bocian exterior and the Supacat winch...
http://www.adeptopensource.co.uk/person ... upacat.jpg

Bocian front cockpit
http://www.adeptopensource.co.uk/person ... 071126.jpg

You can get the bocian / supacat and ask21 from CVS, though you'd ideally need fgfs-0.9.11-pre2 to fly them.

Though my limited spare time is currently being spent on the Buccaneer, I'm happy to help with any problems you need assistance with. Having access to the real aircraft is always a great boon for modelling, and I'm sure we can help you model pretty much any aspect of the Grob you want in FG.

Cheers,

AJ
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Postby gliderace » Mon Nov 26, 2007 8:53 pm

AJ,
Thank you indeed for the quick reply. I am also heartened to see soaring pilots, here! Darin Meyers happens to fly at my airport (Caddo Mills 7F3) and sent out a notice to us pilots to try FG. I have been a modeler for X-Plane for years and getting into FG is quite new, but very interesting!

I do believe that YASIM would be a better engine, but didn't know where I was going wrong...good to know it is my version (I am using the regular release version of 0.9.10).

In that event, I cannot wait for 0.9.11...! I want to get a good YASIM model up for the Grob and like the fact that YASIM can support tows. I have been wanting to re-create the Piper Pawnee that we use as a tug at our airport and I think that would be a wonderful addition to our soaring efforts.

Again, thanks for the reply and I will look forward to 0.9.11 (unless, that is, I can get my hands on it somehow?). I will also download the Bocian and see what I can use from there. Good points!

Sonny
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Postby HHS » Mon Nov 26, 2007 9:06 pm

Hi,

Great to hear about another great glider, and very nice to hear that it is converted from X-Plane to Flightgear!

I'm not sure about, but I remember having had a flight in a G103 at my local glider place EDSL as a young boy.

I did the ASK21 and like AJ said before, with the new coming release it is no problem with YASim and gliding.

1) Visually, I am still working on it...it is getting there, but the 'right' side seems to have some unusual shading (I tried making surfaces two-sided via Blender in UVFaceSelect, and still have some strangeness). This is best seen from the cockpit, looking to the right wing and then craning around to look at the left wing. The cockpit is 3D, and with minimal instrumentation for now.


Your problem is the "normals" - are you using Blender? If you use blender - try "shift-N" - it should solve the problem.

Still having my own projects like LSZH, EC135, Boeing 737-300, Tornado I have little time to help you with the yasim-model.

Are you using Mircosoft? Then it is no problem to get an actual CVS-Version and the pre-release of 0.9.11!

Regards
HHS

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Postby gliderace » Mon Nov 26, 2007 9:26 pm

Hi HHS!
My, but that ASK is a beauty! I sure am envious. You certainly set the bar high and I am aiming for it. Great sailplane!

I am using MS, and I think I'll just drill down and get the pre-release of FG at the 0.9.11 version. With that in mind, I am going to re-do my JSBSim file to make a YASIM approximation. I do like the fact that JSBSim allows me to use good polar values for CL, etc. for an airfoil, but I like YASIM in that it 'seems' to pay attention to aerosurface placement and is a little easier to read, haha!

Thanks for the input on normals. I'll wrestle with those again and let you all know how it goes.

Cheers,
Sonny
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Postby HeliFlyer » Tue Nov 27, 2007 1:05 pm

Hi gliderace,

first, I like the idea very much that there might be some more interest on soaring with FlightGear.

I tested you nice aircraft and have some remarks

1. Make it compatible with PLIB
Your both main *.ac files link to *.png graphics but the attached files use *.rgb (what really is the FG format). This works with FG/OSG CVS as a lot of graphic formats are supported and the link to *.png is passed on *.rgb.
But it does not work with the FG/PLIB version, your aircraft is without paint from the outside.
So I changed all *.ac files (*.png -> *.rgb) and it works fine on both FG versions.

2. Make the *.rgb small
I loaded your *.rgb files into GIMP and saved it with "aggressive" compression. That is the best for FG handling.

3. Your glider uses the JSB flightmodel. That is fine for the very basic thermal system which we already have ("Dave Culp").
At the moment there are some ugly features by design, ie. you have to put this to every single glider so that the "thermals" (ok, only some dark clouds ...) are displayed.
<!-- set clouds to match thermal scenario -->
<environment>
<clouds>
<status>true</status>
<layer n="0">
<coverage>scattered</coverage>
<elevation-ft>6000</elevation-ft>
<thickness-ft>600</thickness-ft>
<transition-ft>150</transition-ft>
<span-m>40000</span-m>
</layer>
<layer n="1">
<coverage>clear</coverage>
<span-m>40000</span-m>
</layer>
<layer n="2">
<coverage>clear</coverage>
<span-m>40000</span-m>
</layer>
<layer n="3">
<coverage>clear</coverage>
<span-m>40000</span-m>
</layer>
<layer n="5">
<coverage>clear</coverage>
<span-m>40000</span-m>
</layer>
</clouds>
</environment>



4.This is what the author writes about the thermals
AI thermals have some limitations, i.e. they don't lean
downwind, they are only cylindrical in shape, they don't
interact with the terrain or weather, and AFAIK they only
work with the JSBSim FDM. Try using the sgs233 model
for a good demonstration.

Dave Culp


5. Long ago, I created a glider scene with a lot of thermals, which works very nice with your (modified) plane:

http://home.arcor.de/vollnhals-bremen/Arnsberg/

(I did not modell downwinds ("negative thermals", only different thermal strength).

6. To make things easy for you, I put the modified plane here for download:

http://home.arcor.de/vollnhals-bremen/A ... 103.tar.gz

Please inform me after downloading so that I can delete it as it is your work in development and I won't spread it without your permission.
It is important that you follow the instructions of this package, please read them. Otherwise it won't work.

Image
(Only one thermal, but there are a lot of them in the scenery)

Image
(Menden-Barge gliderfield, you start here)
Last edited by HeliFlyer on Tue Nov 27, 2007 10:35 pm, edited 1 time in total.
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Postby HHS » Tue Nov 27, 2007 2:54 pm

Hi,

just a note:

With yasim is thermal possible too!
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Postby gliderace » Tue Nov 27, 2007 9:34 pm

Heliflyer,
Thank you so very much! Wonderful work.
I just d/l your modifications and am going to crack it open to see what has been done. Yes, I did have PNG references in there...I thought I changed all of that, but with juggling between this and X-Plane, I must've gotten lost. Thanks , again.
Great work, that you've done. I really like the collaboration, here!
More updates to follow...
Sonny
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Postby HeliFlyer » Tue Nov 27, 2007 11:09 pm

Hi gliderace,

So I changed all *.ac files (*.png -> *.rgb) and it works fine on both FG versions.


This is the corrected part of my post. I think, you understood it the way it was meant - I changed all texture-names within the *.ac files from *.png to *.rgb.

The upcoming (December???) new FlightGear version 0.9.11 still uses the PLIB display system, the new OSG display system which we already have for the CVS development branch is planned to replace PLIB for further official FlightGear versions.

If you have some time left, try my Menden-Barge (=Arnsberg) thermals scenario. I am especially interested to hear if I should make them stronger and/or change the diameter.

Dave Culp is the author of the code but you or I can config every single thermal, it is clear text (*.xml file in data/AI, "MendenThermal3.xml").
There are also thermals around KSFO, created by Dave. The sample is named "thermal_demo.xml".
I hope that there might be some further development on this part of FlightGear from the coder-side in the future if there is an increasing interest. Thermals should be a dynamical system, come and go like in real life. But as I cannot do this work, we could use the existing ones and make them more realistic (strengh, diameter, using "negative" thermal zones). And there might be a chance to switch them on/off accidentally with some Nasal code, just an idea.

The ReadMe.txt within my glider-package shows you how to enable these AI-files within the "preferences.xml" file. It does not hurt to enable both AI-files at the same time as they influence different parts of the world.

Don't follow the example of the SGS232 set-file to activate an AI-scenerio within the aircraft-file. This was good at the time we had only ONE thermal-AI-file but prevents the use of other thermal-files with such an aircraft. I deleted that part from my SGS232 set-file to be able to use this glider with different thermal-files I have created for my fun.

Enough for now, just ask if there are questions left :-)

Georg
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Postby tbones » Thu Dec 27, 2007 12:08 am

Great work! Thank you!

Might be a little OT but is any touring motor glider developed so far? If not, the Scheibe SF25 would be a good start or, if one wants to stay with Grob, the G109.
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Postby technobill » Fri Dec 28, 2007 8:14 am

Hello,


The whole thing really boggles my mind (I'm a self-proclaimed computer retard) but I do know that there's a new version of Flight Gear (v1.0)


Meanwhile, the pictures are nice.



(That last sentence really epitomes my ignorance of all things computer)
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Postby tbones » Tue Jan 08, 2008 5:07 pm

Is it very hard to define a touring motor glider that reacts like the original in both domains?
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Postby HHS » Tue Jan 08, 2008 8:52 pm

Depends on the datas you have ...But should be no problem.
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Postby tbones » Wed Jan 09, 2008 12:06 am

I see you´re from Germany. The SF 25 Falke is quite common there. What kind of data is needed?

A more international and modern solution could be the HK 36 Super Dimona. I recently saw TMGs with CVFR instruments, but that´s too much for a start with this aircraft category :D
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Postby HHS » Wed Jan 09, 2008 3:47 pm

Hi,

with JSBSim it would be good to have some windtunnel datas, but only the airfoil alone could be enough too. With a little help by Datcom you should get a quite realistic flightmodel ( like the SenecaII)

with YASim you need some perfomance datas - that means a lot of tweaking. Should be no problem if you fly these one in real life.

The Falke is very common here - most of the glider clubs use this nice aircraft.

There is an ASK 21 for download at www.flightgear.org - Schleicher did a motor version of this sailplane:
http://www.alexander-schleicher.de/index_e.htm
->ASK 21 Mi

I wanted add these aircraft, but because of some private projects ( new job, loooking for a new appartement) I don't have the time now.

It should be easy to make it: add the motor, fake air drag of the motor with the gear-property.....

But a real tourig-motorglider like you mentioned would be great!

Regards
HHS
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