Board index FlightGear Development Aircraft

Sailboats

Questions and discussion about creating aircraft. Flight dynamics, 3d models, cockpits, systems, animation, textures.

Sailboats

Postby saturn5 » Fri Aug 15, 2008 1:55 am

Anyone have thoughts on the feasibility of a FG sailboat, or if they have worked on (or known of) such as concept.

Some thoughts:
If a FDM could be adapted to calculate the forces on a the sail (sort of like half a wing), then the forces of the water on the boat would need to be factored in (perhaps this is easier with the 1.0 or CVS updates). I was thinking it is the same forces that would effect any seaplane sitting on the water when it is windy, it is just that a sailboat can make use of it differently. However, I am ignorant of the coding expertise needed to understand how feasible this is in practice in FG.
saturn5
 
Posts: 102
Joined: Fri Jan 04, 2008 9:32 pm

Re: Sailboats

Postby erik » Fri Aug 15, 2008 7:54 am

To be honnest I wouldn't be surpriced to see a properly designed sailboat (with one vertical wing) in YASim would work quite reasonable already. I know it already handles different ground surfaces differently but am not sure whether viscosity of water is implemented.

Erik
erik
 
Posts: 505
Joined: Thu Nov 01, 2007 1:41 pm

Re: Sailboats

Postby saturn5 » Fri Aug 15, 2008 2:20 pm

I am curious how the flight data models, could be adapted to model water interaction. On one hand perhaps its possible to adjust density and other variables to water, however the equations for modeling air might not be the most efficient for modeling hull to water interactions. I mean water is nearly incompressible in this case, but then there is things like cavitation and two-phase flow to worry about.

Just thinking about this, I think what is needed for a sailboat, and for that mater also for boats and seaplanes in general is a more advanced water dynamics model for FG. If we can find someone who understands how to model water to hull interactions, then we would know what technical data is needed water part. Maybe there is open source water dynamics model floating around out there somewhere!

As for the sails, modeling the sails with an existing FDM seems logical to me also, but I don't know enough. I mean, modeling sails would be tricky because the wind can effect there shape which would in turn effect the forces on the boat and in turn effect the apparent wind speed and direction. Although, perhaps this taking too complicated approach- I just don't know.
saturn5
 
Posts: 102
Joined: Fri Jan 04, 2008 9:32 pm

Re: Sailboats

Postby revilo » Wed Aug 27, 2008 8:50 pm

The profile of a sail is depending on wind speed, approach angle, etc. Unlike the wing of a plane it is extremely flexible.
Thus, the YASIM configuration for "stall aoa", "with" and "peak" will lead to anything but realistic sailing.
On the other hand the "gear" function in YASIM works quite well for boats in water.

revilo
revilo
 
Posts: 14
Joined: Fri Feb 16, 2007 10:10 pm

Re: Sailboats

Postby DFaber » Thu Aug 28, 2008 5:36 am

revilo wrote:Thus, the YASIM configuration for "stall aoa", "with" and "peak" will lead to anything but realistic sailing.
On the other hand the "gear" function in YASIM works quite well for boats in water.


Your perfectly right here, I've already tried it.

But I'm thinking of a different approach. One can use Nasal, to calculate the resulting force and orientation of a sail based upon windspeed and use thrusters to emulate the forces on the Mast. Thrusters don't use fuel and need no engine.

I tried some first ships here:

http://www.sol2500.net/flightgear/ships.zip

This is Rons excellent Oscar Sette Model modified to be steerable and a steerable SAR ship that I created as AI Model (hence the poor detail level).

As I am not a sailor, maybe someone with maritime knowledge can comment on it.

I'll happily try a sailboat, but I don't have a Model yet.

Greetings
Detlef Faber
FlightGear Development:
http://flightgear-de.net

German FlightGear Forum
http://forum.flightgear-de.net
DFaber
 
Posts: 577
Joined: Fri Dec 01, 2006 7:51 pm
Location: Aachen, Germany
Version: GIT
OS: Linux

Re: Sailboats

Postby glazmax » Thu Aug 28, 2008 9:46 am

But I'm thinking of a different approach. One can use Nasal, to calculate the resulting force and orientation of a sail based upon windspeed and use thrusters to emulate the forces on the Mast. Thrusters don't use fuel and need no engine.


Nice idea!

What about waves and the looks of the water surfaces we have. In my opinion these also need remodeling, but what method to use:
- different textures (for different wind speeds and depths)
- make models for small and medium waves and animate them

Hmm, I like the look of water from silent hunter III, does anyone know which technology they use?

This belongs more to scenery I know, but I am just curios from the modeling approach.

Sail on,
glazmax
XXX pilot of the caribbean - bones and porters XXX
User avatar
glazmax
 
Posts: 454
Joined: Sat Jan 27, 2007 10:38 am
Location: Austria
Callsign: jettoo/OE-JTO
Version: cvs

Re: Sailboats

Postby DFaber » Thu Aug 28, 2008 10:09 am

Hi glazmax,

glazmax wrote:- make models for small and medium waves and animate them


... I tried this with quick modelled static 3d waves and the Ships. It gives a quite satisfying bumpy ride :-) . Nothing for weak stomachs. However the waves appear as solid ground, so I had to make the "water" gears to "land gear" again.

If we could assign specific ground properties to 3d Models it would be perfect. The waves could be scaled along z-axis to simulate wave height and rotated to fit to the wind direction. The waves could be placed as random objects and controlled either by a global nasal script or a Wave controller placed somewhere in the scenery.

Just a bunch of ideas ...
Detlef Faber
FlightGear Development:
http://flightgear-de.net

German FlightGear Forum
http://forum.flightgear-de.net
DFaber
 
Posts: 577
Joined: Fri Dec 01, 2006 7:51 pm
Location: Aachen, Germany
Version: GIT
OS: Linux

Re: Sailboats

Postby glazmax » Thu Aug 28, 2008 10:30 am

Good ideas!

If we could assign specific ground properties to 3d Models it would be perfect. The waves could be scaled along z-axis to simulate wave height and rotated to fit to the wind direction. The waves could be placed as random objects and controlled either by a global nasal script or a Wave controller placed somewhere in the scenery.


I think we can do that, we have the scale animation:
Code: Select all
<animation>
  <type>scale</type>
  <object-name>ShadowMap</object-name>
  <property>position/altitude-agl-ft</property>
  <x-factor>0.05</x-factor>
  <x-offset>1.0</x-offset>
  <y-factor>0.05</y-factor>
  <y-offset>1.0</y-offset>
  <z-factor>0.0</z-factor>
  <z-offset>1.0</z-offset>
  <center>
   <x-m>0.05</x-m>
   <y-m>0.05</y-m>
   <z-m>0.0</z-m>
  </center>
 </animation>


the rotation should also be no problem :)

but should the waves move (according to wind speed x factor) or stay fixed?
XXX pilot of the caribbean - bones and porters XXX
User avatar
glazmax
 
Posts: 454
Joined: Sat Jan 27, 2007 10:38 am
Location: Austria
Callsign: jettoo/OE-JTO
Version: cvs

Re: Sailboats

Postby erik » Thu Aug 28, 2008 10:32 am

The 'bumpiness' factor in materials.xml of the base package should be sufficient for simulating waves I think, maybe it should be adjusted a bit.

Erik
erik
 
Posts: 505
Joined: Thu Nov 01, 2007 1:41 pm

Re: Sailboats

Postby glazmax » Thu Aug 28, 2008 10:42 am

erik wrote:The 'bumpiness' factor in materials.xml of the base package should be sufficient for simulating waves I think, maybe it should be adjusted a bit.

Erik


But as far as I know we cannot assign a material to a 3d model yet, or has this barrier fallen?
XXX pilot of the caribbean - bones and porters XXX
User avatar
glazmax
 
Posts: 454
Joined: Sat Jan 27, 2007 10:38 am
Location: Austria
Callsign: jettoo/OE-JTO
Version: cvs

Re: Sailboats

Postby DFaber » Thu Aug 28, 2008 12:46 pm

erik wrote:The 'bumpiness' factor in materials.xml of the base package should be sufficient for simulating waves I think, maybe it should be adjusted a bit.
Erik


I tried that already. For larger ships there is no effect if the bumpiness is increased. A small Seaplane may feel a difference though.

Assigning ground properties to 3d Models offers some more advantages than on the water. Driving with the jeep over bridges is currently a bumpy experience.
It would enable us to model usable streets or rivers and lakes in 3d, to land a seaplane on. The Courcheval Airport wouild profit too.
Detlef Faber
FlightGear Development:
http://flightgear-de.net

German FlightGear Forum
http://forum.flightgear-de.net
DFaber
 
Posts: 577
Joined: Fri Dec 01, 2006 7:51 pm
Location: Aachen, Germany
Version: GIT
OS: Linux

Re: Sailboats

Postby HHS » Thu Aug 28, 2008 1:48 pm

glazmax wrote:Nice idea!

What about waves and the looks of the water surfaces we have. In my opinion these also need remodeling, but what method to use:
- different textures (for different wind speeds and depths)
- make models for small and medium waves and animate them

Hmm, I like the look of water from silent hunter III, does anyone know which technology they use?

This belongs more to scenery I know, but I am just curios from the modeling approach.

Sail on,
glazmax


Hi,

The idea of using 3d-models for waves is imho very bad and not uptodate in game/ simulation graphics!
There is a lot of space for developement in graphic: missing shadows, landinglights, the sky (not the astrosystem!), terrain ( we can't render the whole earth from very heights) and last but not least, water.

Su much as I know in OSG is an example of rendering water with moving waves and reflections. Another game using OSG has something like that implemented: http://www.openscenegraph.org/projects/osg/wiki/Screenshots/Pirates.
And X-Plane, another simd using OpenGl has water with moving waves implemented- and the framerates semms not very bad.

Realistic acting and working sailboats would be very nice and would show how realistic FlightGear can act.
But it would be great if we could assigning ground properties to 3D-models. Modelling an airport with a forest inside would be much easier and more framerate-friendly as an another example.

Cheers
HHS
Up, up and away
User avatar
HHS
Retired
 
Posts: 3624
Joined: Thu Jul 19, 2007 8:09 am
Version: GIT

Re: Sailboats

Postby DFaber » Thu Aug 28, 2008 3:03 pm

HHS wrote:The idea of using 3d-models for waves is imho very bad and not uptodate in game/ simulation graphics!
There is a lot of space for developement in graphic: missing shadows, landinglights, the sky (not the astrosystem!), terrain ( we can't render the whole earth from very heights) and last but not least, water.


Well, it is the easiest approach to create waves the current vehicles can drive/slide up and down. I agree it would be better to do waves in the scenegraph, but I am no programmer to implement this :-(

Greetings
Detlef Faber
FlightGear Development:
http://flightgear-de.net

German FlightGear Forum
http://forum.flightgear-de.net
DFaber
 
Posts: 577
Joined: Fri Dec 01, 2006 7:51 pm
Location: Aachen, Germany
Version: GIT
OS: Linux

Re: Sailboats

Postby HHS » Thu Aug 28, 2008 5:03 pm

DFaber wrote:
HHS wrote:The idea of using 3d-models for waves is imho very bad and not uptodate in game/ simulation graphics!
There is a lot of space for developement in graphic: missing shadows, landinglights, the sky (not the astrosystem!), terrain ( we can't render the whole earth from very heights) and last but not least, water.


Well, it is the easiest approach to create waves the current vehicles can drive/slide up and down. I agree it would be better to do waves in the scenegraph, but I am no programmer to implement this :-(

Greetings


Yeah- I know this issue to well.... :(
I'm no programmer too, and should be better quite, but I hope that maybe there will be some person who read this and contribute....

Regarding waves- so much as I know, waves are implemented on the ocean and even depending on the weather. But so much as I know, not the height of the waves, directions etc.....
Up, up and away
User avatar
HHS
Retired
 
Posts: 3624
Joined: Thu Jul 19, 2007 8:09 am
Version: GIT

Re: Sailboats

Postby glazmax » Thu Aug 28, 2008 11:07 pm

I'm no programmer too, and should be better quite, but I hope that maybe there will be some person who read this and contribute....


Forget it, what I have learned out of the process of 3d modeling is to try an attempt, if then people get curious and want to help: fine, but don't rely on imagination.

Currrently people try to implement shaders, which means in detail landing lights and shadows, but waves(ocean) are more sophisticated to model in my opinion. Why? Because you need a 3d model and a simulation model seaplanes, boats have to respond to and those 2 models have to be in sync to be authentic. So to model 3d waves that are present optical and for a model is not a bad idea for me. Sure, for the appearence of water, there can be different approaches to look believable, and effects can be added, but basically you have to see and feel a wave.
So I think detlefs idea is quite good, it just needs the finishing touches in my opinion :)

Fly on,
glazmax
XXX pilot of the caribbean - bones and porters XXX
User avatar
glazmax
 
Posts: 454
Joined: Sat Jan 27, 2007 10:38 am
Location: Austria
Callsign: jettoo/OE-JTO
Version: cvs

Next

Return to Aircraft

Who is online

Users browsing this forum: No registered users and 7 guests