Board index FlightGear Development Aircraft

How to make an Aircraft....

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

How to make an Aircraft....

Postby HHS » Tue Sep 29, 2009 7:07 pm

...some substantial things!

You want to create your first own aircraft? Great! :D

But before you you start- some really substantial things!

1. The question of Licence
Do you want it to have completly as Open Source or more protected?

GNU GPL? GNU GPL stands for OpenSource and the licence for the whole FlightGear FlightSimulator Project- if you want to see your aircraft included in FlightGear you have to choose GNU GPL! But beware of, that it may be sold and be changed by other users, and spreaded further under the same licence!
http://en.wikipedia.org/wiki/GNU_GPL
Very important: This means that you can't use things from other aircrafts which aren't under GNU GPL!

Freeware? Fine, but this means it can't be included in FlightGear's Downloads, and you should have at least a place for your work to offer.
http://en.wikipedia.org/wiki/Freeware

Or how about Creative Common Licnence?
http://creativecommons.org/licenses/by-nc-sa/3.0/
This allows different grades of protect- from totally free to totally protected.

At least - to have it finally under GNU GPL is the one of best thing and a win for the whole project!


2. Collect informations as much as possible!
* What is this exactly for an aircraft, how and when was it used?

-> Your favourite searchengine is your friend- use it! There is also wikipedia, and tons of aircraft pages to look for.
At the end you should at least know:

    -some develpement specs of the aircraft

    -dimensions and weights, fuel specs

    -possible derivates

    -specifics

    -rough specs about velocities, landing speed, cruise levels...
And maybe flight manuals and Operating Handbooks! But beware of, that the most aren't free legal available and isn't important for the beginning....

Use the FG-Wiki: http://wiki.flightgear.org/index.php/Aircraft_Information_Resources

As an example: a 737-800 is not a 737-300 with winglets though it may look like that on the first glance...

*Good Drawings
->Your favourite searchengine is your friend- use it! There is also wikipedia, and tons of aircraft pages to look for.
Just google "aircraftname" 3 views or blue prints- you will find for sure a ot of good drawings!
And have a closer look here in the FG-Wiki: http://wiki.flightgear.org/index.php/Modeling_Resources

Often RC-Aircraft forums offers as well plenty of detailed drawings. You can also find pages there which includes very detailed drawings for a small fee.

*Lots of Photos, Photos, Photos and Images
Even the best and detailed drawing doesn't show you all! Sometimes the fuselage has shapes which can't be seen like that on the drawing!
So collect a large set of photos of Fuselage, Nose, Tail, Wings and Gears!

3. the right Flight Dynamic Model
Choose the right fdm!
We use two important but different fdm's in FGFS: YASim and JSBSim.

-YASim simulates the effect of the airflow on the different parts of an aircraft. It is qite similar to X-Plane's fdm (but no conbversion possible) It should be used if you only have the dimensions of the aircraft and some rough specs. It also provides a quite realistic helicopter fdm, so for helicopters YASim is currently most best at the moment.
This will help you with YASim: http://ltts.crlt.indiana.edu/grn/flightgear/yasim_1.html

-JSBSim is a generic, 6DoF flight dynamics model for simulating the motion of flight vehicles. This is great if you have detailed flight datas like airfoils, windtunnel and perfomance datas.
It comes with a nice tool, which helps to develope a fdm which suits quite good to real aircraft and is the base for a perfect fdm!
http://jsbsim.sourceforge.net/aeromatic2.html. And at least there is Datcom, a tool used be the US-Airforce for developement:
http://www.holycows.net/datcom/

For the beginning you could use a similar aircraft's fdm.
In the direction where you stored FGFS you will find more help about: data/Docs/....README

4. fundamental things on 3d-modelling
First: for modelling aircrafts you need some skill.

You don't have? :shock:

No problem! 8) On the web there are hundreds and more tutorials which help to learn 3d-modelling! So practice the most important shapes used like cylinders, Cubes, Quaders, Poly-by-Poly-modelling etc. before you really go on and announce your project! Otherwise you might disappoint other users ....

Some additional tips:

    -for the first make a rough model than add details

    -texture mapping should be the last thing you do after finishing the aircrafts fuselage. Only map the aircraft if you are sure you are ready and futher changes won't change the mapping. If not it may upsets Livery makers and make it hard to change all liveries made already.

    -to few vertices and polygens? Hey, aircrafts has usually soft edges and round fuselages - and even older computers can manage a lot of polygens so do not save with! As many vertices as needed- not more or less!

    -regards the normals- the most 3d-modelling-programs shows the directions of the normals. If you disregard this, don't wonder why some surfaces are unvisible!

    -use setsmooth or anything similar in your 3d-modelling program to have smooth curves and surfaces.

5. Animations and configuring
No, there aren't great programming skills needed. All the aircrafts mostly shares the same code snippets!
So first take a look on other aircrafts and at the Model-How-To, which is included in yor FlightGear-Program in data/Docs/Model-How-To.

You want some fancy animations like pushback, lights, weapons etc.? Befor you do that- be sure you have understand how all the animations works and the basic ones on your aircraft works correct.
These are:
-Rudder
-Aileron
-Elevator
-Trim surfaces
-Gear

And be sure that the modell is good positioned- no "hovering" above the ground, or wrong contactpoints.

6. converting from other sims
Some other sims use similar model-formats. Or some can be easily converted to FGFS's format. So it is possible and maybe the easist way to get a new aircraft.

But:
-you can't convert the fdm- it has to be written completly new like animations etc!

-ask the original-author! Without his permission you aren't allowed to convert his work. Include your request and his answer in an extra text-file, so everybody can be sure that you didn't infringed copyrights!

-Be polite when requesting permission and respect when he says no!

Finally- how the get my aircraft on FlightGear.org and available for all?

Public or private spaces like unitedfreeworld, avsim etc. are good place to share for the community while developing and for a first release.
But the best place is still GIT, the developement system of FlightGear Project!
The place for all developement -aircrafts, programmings, graphics...- is the mailing-list and the IRC-Chat!
So if your Aircraft is really GNU GPL ask on the devel-list or in the forum if someone might take quick look at it and upload it! So whenever the next release comes-it will be available for all and easy then!
https://lists.sourceforge.net/lists/listinfo/flightgear-devel
irc.flightgear.org, channel = #flightgear

At least
A good aircraft needs time!
Maybe the fuselage is done in some hours or days. But tuning fdm, programming systems etc. needs a lot more. And making the cockpit needs about 10x more time then the exterior model! So be yourself patience!

You are stucked some where?
Don't hesitate to ask! But give some detailled description where and why it is stucked. Otherwise there won't be much help! And the most developers are already quite good recognizing if you really want help or just want them to make your work! :wink: :lol:

Happy developing!

Edit: adding set smooth hint
Edit2: added suggestions by GRTux
Edit3: added suggestions by MOJO
Last edited by HHS on Fri Dec 17, 2010 5:18 pm, edited 8 times in total.
Up, up and away
User avatar
HHS
Retired
 
Posts: 3624
Joined: Thu Jul 19, 2007 8:09 am
Version: GIT

Re: How to make an Aircraft....

Postby Gijs » Tue Sep 29, 2009 7:14 pm

Awesome article Heiko! I'm very sure this will attract some more developers, or atleast give those that want to start developing a nice help!
I would be very honored if you could add (parts of) it to the wiki: http://wiki.flightgear.org/index.php/Ho ... n_aircraft

Thanks!
Gijs
Airports: EHAM, EHLE, KSFO
Aircraft: 747-400
User avatar
Gijs
Moderator
 
Posts: 9304
Joined: Tue Jul 03, 2007 2:55 pm
Location: Amsterdam/Delft, the Netherlands
Callsign: PH-GYS
Version: Git
OS: Windows 10

Re: How to make an Aircraft....

Postby HHS » Tue Sep 29, 2009 7:18 pm

Gijs wrote:Awesome article Heiko! I'm very sure this will attract some more developers, or atleast give those that want to start developing a nice help!
I would be very honored if you could add (parts of) it to the wiki: http://wiki.flightgear.org/index.php/Ho ... n_aircraft

Thanks!
Gijs

As the most people look first in the forum, it might be better to be sticky! The wiki has the additional infos you need
Last edited by HHS on Wed Sep 30, 2009 11:26 am, edited 1 time in total.
Up, up and away
User avatar
HHS
Retired
 
Posts: 3624
Joined: Thu Jul 19, 2007 8:09 am
Version: GIT

Re: How to make an Aircraft....

Postby NiTuS » Tue Sep 29, 2009 9:06 pm

I feel comfortable at XML programming, but 3D modelling is just annoying for me... :D
Good Topic, Heiko!
NiTuS
 
Posts: 113
Joined: Sun Jul 29, 2007 3:04 pm
Callsign: EC-NIT
Version: 2017.3.1
OS: Windows 7 64bit

Re: How to make an Aircraft....

Postby jonbourg » Wed Sep 30, 2009 2:40 am

Good article! I also agree this should be a sticky!
jonbourg
 
Posts: 329
Joined: Tue Mar 11, 2008 12:43 am
Location: Omaha, NE
Callsign: BU2B
OS: Windows8

Re: How to make an Aircraft....

Postby Fahim Dalvi » Wed Sep 30, 2009 8:03 am

Nice one Heiko! This should Definetly be a sticky!
Fahim Imaduddin Dalvi
Tracker, Flight Gallery
User avatar
Fahim Dalvi
 
Posts: 1286
Joined: Sun Oct 14, 2007 1:08 pm
Location: Qatar
Callsign: Fahim
Version: 2018.2.2
OS: MacOS

Re: How to make an Aircraft....

Postby grtux » Wed Sep 30, 2009 9:08 pm

HHS wrote:...some substantial things!

You want to create your first own aircraft? Great! :D

But before you you start- some really substantial things!

1. The question of Licence
Do you want it to have completly as Open Source or more protected?

GNU GPL? GNU GPL stands for OpenSource and the licence for the whole FlightGear FlightSimulator Project- if you want to see your aircraft included in FlightGear you have to choose GNU GPL! But beware of, that it may be sold and be changed by other users, and spreaded further under the same licence!
http://en.wikipedia.org/wiki/GNU_GPL
Very important: This means that you can't use things from other aircrafts which aren't under GNU GPL!

Freeware? Fine, but this means it can't be included in FlightGear's Downloads, and you should have at least a place for your work to offer.
http://en.wikipedia.org/wiki/Freeware

................................................................

-JSBSim is a generic, 6DoF flight dynamics model for simulating the motion of flight vehicles. This is great if you have detailed flight datas like airfoils, windtunnel and perfomance datas.

...........................................................
Happy developing!

Edit: adding set smooth hint



Great Article

May i add two remarks ( i hope useful )

==>Regarding the choice of Licence in the "Freeware" category there is an other one,

http://creativecommons.org/licenses/by-nc-sa/3.0/

==>Regarding the JSBSim FDM you may use it even if you don't have the datas like airfoils, windtunnel and perfomance datas ( these informations could come later on )
First you only have to use the perfect tool Aeromatic

http://jsbsim.sourceforge.net/aeromatic2.html

with it, it does take only 5 minutes to generate the FDM files, which will suit to your Aircraft.
You only have to answer to the questions , area, wingspan, lenght, engine power .... etc

Trust me it is Very easy to use.

Cheers
g.robin
LFMO
User avatar
grtux
 
Posts: 432
Joined: Thu Dec 14, 2006 4:19 pm
Location: Provence France

Re: How to make an Aircraft....

Postby HHS » Thu Oct 01, 2009 12:18 am

grtux wrote:[
Great Article

May i add two remarks ( i hope useful )

==>Regarding the choice of Licence in the "Freeware" category there is an other one,

http://creativecommons.org/licenses/by-nc-sa/3.0/

==>Regarding the JSBSim FDM you may use it even if you don't have the datas like airfoils, windtunnel and perfomance datas ( these informations could come later on )
First you only have to use the perfect tool Aeromatic

http://jsbsim.sourceforge.net/aeromatic2.html

with it, it does take only 5 minutes to generate the FDM files, which will suit to your Aircraft.
You only have to answer to the questions , area, wingspan, lenght, engine power .... etc

Trust me it is Very easy to use.

Cheers


Thanks for your inputs!

I added the Creative Common Licence and and added your suggestions to JSBsim. Though I'm pretty sure that Aeromatic is not so good like using windtunnel datas and aother things, but you are right, it is the perfect base for that! :D

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

Re: How to make an Aircraft....

Postby grtux » Thu Oct 01, 2009 11:00 am

HHS wrote:Thanks for your inputs!

I added the Creative Common Licence and and added your suggestions to JSBsim. Though I'm pretty sure that Aeromatic is not so good like using windtunnel datas and aother things, but you are right, it is the perfect base for that! :D

Thanks!



Yes, when we have windtunnel datas and other things, the FDM would be the best, the simulation accuracy can be very , very high.

But, one, can know that it is NOT =>so difficult to use JSBSim<= ( i heard it very often ) , even if we are missing these accurate data.

I don't know for anybody else , but to me, that Aeromatic tool was/is very useful to start a new model since , i get quickly ( very quickly, 5 minutes) a flying model.

If necessary, with these resulting files i can do everything i want => to include tunnel data, => to include some specific behaviour under condition, or => more simple, to modify some drag and lift values. The flexibility with is great,

This could look like an advertising :) :
"With Aeromatic, JSBSim can be used by any non expert people"

Cheers
g.robin
LFMO
User avatar
grtux
 
Posts: 432
Joined: Thu Dec 14, 2006 4:19 pm
Location: Provence France

Re: How to make an Aircraft....

Postby 2011futuremarine » Thu Oct 01, 2009 1:54 pm

Thanks for this, HHS! :D
Aircraft: primarily military
User avatar
2011futuremarine
 
Posts: 972
Joined: Thu Jun 05, 2008 8:19 pm
Location: USA
Callsign: Dodger4

Warm Toasty Bagels

Postby Mobius1 » Tue Oct 20, 2009 12:34 am

Thanks! This encourages me to build an aircraft, but no promises!!!



:D
I'm back!

Anxious to start MPing again!
Mobius1
 
Posts: 72
Joined: Mon Sep 07, 2009 9:56 pm
Location: Chester, SC (KDCM)

Re: How to make an Aircraft....

Postby Andrew » Tue Nov 10, 2009 12:31 am

How do you do the engine rpm?
Andrew
 
Posts: 2
Joined: Mon Nov 09, 2009 1:11 am

Re: How to make an Aircraft....

Postby MOJO » Tue Nov 17, 2009 3:29 pm

Hi,

I'm thinking about entering the unknown and trying t make my first aircraft which will be the C-17 Globemaster but before I start on this could someone answer me a couple of hings first;

1) When modelling, do things like doors, landing gear doors, spinning engines and stuff have to be seperate objects as they are going to be animated?
2) I've seen peoples models in blender and they seem to have aircraft blue prints on the screen, does this make it easier to model an aircraft?

If I think of anything else to ask I'll post again.

Thanks

MOJO
F-18 Hornets by Mandate - F-14 Tomcats by Choice
User avatar
MOJO
 
Posts: 718
Joined: Fri Jun 26, 2009 11:41 am
Location: Sheffield, UK
Callsign: MOJO
Version: 2
OS: Windows Seven

Re: How to make an Aircraft....

Postby Gijs » Tue Nov 17, 2009 3:56 pm

Hi MOJO,

we already have a C-17 Globemaster, though it has not been released yet. So you might pick another aircraft before doing already-done-work...

1) Yes, if you want to animate anything, it always have to be a seperate object. However, you can cut these things out later on, after you finished the fuselage/wings.
2) Blue Prints make it much easier (you could use photographs aswell, but make sure they were taken in a 90 degrees angle to the plane (side, front). Obtaining top view photographs might be hard though). Using blue prints (which often also have a couple of measurements written down) you are able to create a 1:1 scale model of the aircraft.

Regards,
Gijs
Airports: EHAM, EHLE, KSFO
Aircraft: 747-400
User avatar
Gijs
Moderator
 
Posts: 9304
Joined: Tue Jul 03, 2007 2:55 pm
Location: Amsterdam/Delft, the Netherlands
Callsign: PH-GYS
Version: Git
OS: Windows 10

Re: How to make an Aircraft....

Postby MOJO » Tue Nov 17, 2009 11:27 pm

Cheers for that Gijs, saved me from doing alot of work lol, I'll find a new craft to to try out.

Regards
F-18 Hornets by Mandate - F-14 Tomcats by Choice
User avatar
MOJO
 
Posts: 718
Joined: Fri Jun 26, 2009 11:41 am
Location: Sheffield, UK
Callsign: MOJO
Version: 2
OS: Windows Seven

Next

Return to Aircraft

Who is online

Users browsing this forum: Bing [Bot] and 14 guests