Designing
Aircraft for FS2004
There's
an adage in aviation which runs "If it looks nice it'll fly nice".
Nothing could be further from the truth with FS2004 and it's earlier editions.
In fact, building an FS aircraft is not an easy process and it gets harder
with each new release.
Almost
anyone can design presentable scenery for FS - they only have to download
a scenery designer and the rest is just a matter of accurate research,
time and effort. When it comes to aircraft design you need more than a
capable design package, you must also learn the basics of aerodynamics
or else a beautiful looking aircraft can end up with all the flying qualities
of a drunken pig.
Many
people start to design an aircraft without any real idea of what is involved.
The usual routine is to begin with the visual model as it's the most exciting
bit and it can be very satisfying seeing your creation slowly grow. Once
this hurdle is out of the way it can come as a surprise that there are
quite a few more stages yet to be tackled - and it is here that enthusiasm
must be maintained, or at least replaced by dogged determination.
On
this page I am not going to run through the whole creation process in
exacting detail - it would take a small booklet to do that - but I would
like to show what is involved so that potential designers see the workload
ahead.
The
Grand Design
If
you are serious about building an aircraft let's look at the stages in
its construction. There are five altogether.
Design
Stage
|
Description
|
Tools
required
|
Visual
Model
|
This
is the physical aircraft design as made in GMax or FSDS. The process
of building the aircraft may also involve a need to animate parts
and to design a Virtual Cockpit.
|
GMax
or FSDS.
Research.
Accurate aircraft plans/good photo's
|
Panel
|
Most
good aircraft now have custom panels. This process may also involve
a need to design custom gauges.
|
Panel
Builder.
Gauge Maker
|
Textures
|
Textures
are applied to the finished model to create surface colours and
detail.
|
A
good paint program like PSP.
ImageTool.
BMP2000 or DXTBmp
|
Sound
|
Engine
sounds for minimal realism. Additional cockpit sounds for added
effect.
|
No
known tool.
|
Performance
|
This
stage creates the files that produce the flying model for the aircraft.
|
FSEdit.
AirEd.
Flight Dynamics Editor (FDE)
|
In
designing your own aircraft some of these stages may be omitted. It is
an easy matter to "borrow" items in your FS inventory, especially
sounds and panels, but there is no escaping the fact that you will have
to create a visual model, its textures and a decent performance file.
The
Visual Model
If
you are going to do any aircraft justice then you have to start off by
knowing as much as you can about the aircraft. Specifications, photo's,
books and plans are all essential before you even think about opening
up GMax of FSDS.
Aircraft
plans are absolutely essential and the larger the scale the better. If
your plans are small scale -1/72 or thereabouts - you will probably have
to enlarge them for this work but this compounds drawing errors. It's
much better to get plans you need to reduce to fit in GMax as these
will give maximum accuracy and detail.
For
my Tiger Moth I was using plans scaled at 1/36 and these were big enough
to show cowling fastenings, fuel lines, control hinges and other fine
detail that is essential when making the model. I am not saying that all
these parts have to be built, but knowing where they are helps you to
understand more about the real aircraft.
At
an absolute minimum you will need top, side and front elevation views
of your chosen aircraft. These will not give you all the detail you need
(the engine on a DH2 is obscured in all these views) and additional plan
detail like rear and bottom views, cross sections, cutaway drawings and
enlarged detail are all worth their weight in gold. You can also use photographs
to supplement the missing detail but be very careful if you make any parts
from photographic sources - it is very hard to estimate correct shape
and size.
For
my Tiger Moth design the plans were extremely good. As well as standard
front, side and top elevations they provided separate drawings for each
major component - tailplane, rudder, top and bottom wings, struts, fuselage
and propeller. As a result it was easy to make these items without having
to interpolate detail form the normal views. For example, the wings on
normal 3 view drawings are already set with dihedral, incidence and sweepback
and it can be very difficult to work out their true shape from this. It
is far easier to build the wing from a "flat" projection and
then add dihedral, incidence and sweepback in GMax.
Having
collected all your data the production of aircraft parts can begin. Plans
can be displayed and correctly scaled in GMax - making life a lot
easier - leaving you to concentrate on obtaining accurate shapes of objects.
If
new to GMax you will spend as much time in the initial stages fathoming
out how the program works as in making aircraft parts. For this reason
it is better to start on less complicated structures like the rudder or
tailplane than the more ambitious fuselage, wings or landing gear. I say
this because you will learn new techniques as work progresses and will
realise that existing parts can be made much better. I rebuilt the Tiger
fuselage three times during construction and I still see ways I could
have improved it.
The
Aircraft Panel
Making
a panel involves two arts - creating a panel bitmap and filling this with
gauges.
For
those of us with limited graphic skills the bitmap can be a nightmare.
If you have a photograph of the panel it helps in producing an accurate
layout but don't think you can use the photo direct in FS2004 - it can
take a lot of work to make it look right. Some of the best FS2004 panels
look extremely lifelike (like the Dreamfleet Warrior) but they are mostly
graphic design work in which the artist has used photos to create the
correct ambience of light and shadow.
For the Tiger Moth I had no option but to use a full screen bitmap for
the panel because the wings had to be included in the view. In monoplanes
you see hardly anything of the aircraft looking forward and the panel
bitmap can be much smaller - maybe just half the screen height.
The
bitmap should be designed with care. It is very easy to get carried away
and end up with a huge panel and very little outside view - some of the
default FS panels are edging towards this - but a small panel is equally
bad in that it increases the area that the outside view has to cover -
which has a direct hit on frame rates. For this reason I slightly "modified"
the Tiger panel and raised the cockpit sides (they are a good few inches
lower on the real aircraft) but in doing so the outside view window only
needed to cover three quarters of the screen rather than the whole area.
Having
made your bitmap you only have to do two things. First you check that
pure black is only used in those areas the outside view is required -
if you accidentally use it on the panel itself you will get a hole through
which the scenery will show through! Next you work out what gauges you
need.
Gauges
Most
people take the easy options and use standard FS gauges - or get permission
to use a gauge built by another designer. It is quite easy to fit any
gauge in your FS Gauges folder on your panel - you can either use a panel
maker program for this or copy and edit an existing panel.cfg file. I
will not cover this in further detail as many other guides are available
for making panels, but the ASI in the Tiger panel.cfg file looks like
this:
gauge01=DHasi_kts,
200,508,123,123
The
line shows the gauge number (these MUST be sequential in the panel.cfg
file), the name of the gauge file, the horizontal offset on the bitmap,
the vertical offset and the width and height of the gauge. In this case
the ASI is 200 pixels left and 508 pixels down and it is 123 pixels square.
The ability to size the gauge is a very handy feature in FS. If the line
above was placed in the panel.cfg file of any other FS aircraft the gauge
would display.
If
you don't find a gauge to suit your requirements then you are going into
deeper waters. Designing gauges prior to FS2004 required a knowledge of
C++ but the old GAU files are now a thing of the past and from FS2004
onwards gauges are XML coded.
A
gauge comprises of a set of bitmaps for the gauge dial, needles, flags
or whatever plus the XML code to position these and control their operation.
The bitmaps and XML files are usually then placed in a CAB file although
this isn't mandatory - but it looks tidier than hundreds of bitmaps and
XML files in the Gauges folder..
For
the ASI gauge above only two bitmaps were used, one being for the dial
face and one for the ASI needle. More complex instruments (like an HSI)
require a lot of bitmaps and rather more complex coding.
Aircraft
Textures
More painting!
The
good news here is that texturing the aircraft isn't as hard as designing
the panel. You don't need to consider shading when creating aircraft textures
- all you need to do is concentrate on detail. The texture is applied
to the aircraft during construction in GMax which is good because it leaves
you free to work on the bitmap without constraints at the initial stage.
There is just one limitation - the bitmap must be square and it's size
must be 256 x256, 512 x 512, 1024 x 1024 or 2048 x 2048.
Try
to cram as much data as you can onto your bitmaps - in fact, have a look
at the bitmaps for the Corsair in FS2002 as they are excellent both in
quality and compactness of detail. Bitmaps are responsible for the huge
size of most aircraft downloads in FS2002 and a little thought in the
design process can cut these down considerably. A single 1024 x 1024 bitmap
in 24 bit colour is over 3Mb..
There
are two ways round this. You can either stay with the 8 bit palette and
limit yourself to 256 colours - in which case each 512 x 512 bitmap is
just 256K (approx). If you want the extra detail offered by FS2004 move
up to 24 bit colours and work with 1024 x 1024 images. Each image will
be 3072K - but if you then open the image in ImageTool and reformat it
as a DXT1 file the size shrinks to just 683K! You may have noticed some
DXT1 files already because if you open them in a paint program all you
see is a garbled image diffused with vertical black banding. Don't touch
DXT files with anything other than ImageTool or DXTbmp.
The
easiest way of painting your aircraft is to scan your drawings into PSP
and, quite literally, colour them in. Each separate image can then be
reduced, copied and pasted into a blank 1024 bitmap and other images added
until this is full. Individual items can be rotated if this improves the
"fit" - as you can see in the bitmap below.
As
you can see the scale of individual parts is not an issue and I haven't
utilised the bitmap to full potential! On the other hand I used some parts
of each bitmap for several aircraft items - part of the yellow wing area
was used for some of the struts and the fuselage colouring (not shown
on this bitmap) was raided several times for small items like pitot tube
and cabane struts.
Sounds
This
will be a very short section!
For
the Tiger Moth I "borrowed" some sound files from an FS98 version
but these behaved strangely to say the least. A look at the sound.cfg
file showed that the format in FS2004 is much more complex than for FS98
and this was confirmed by a look at the SDK. I'll admit that I got lost
very quickly, although fade in time, fade out time, transition and other
effects might be easily understood by those of you who have worked with
sound files before.
I
opted out and emailed Mike Hambly in the hope that he might take pity
on yet another designer who has stepped in a puddle only to find it a
flooded mineshaft.. Mike not only responded but provided a new Gipsy Major
sound set for FS2004 by return of post. A wonderful gesture from a real
gentleman considering I'd never spoken to him before..
Aircraft
Performance
The
aircraft performance file is the most important part of an aircraft design.
It is the ONLY file that "tells" the aircraft how to behave
in flight (or even to fly at all) and an aircraft that flies badly is
a great disappointment to any FS user - no matter how nice it looks.
There
is no interaction between the visual model and the performance file at
all. You can make a simple box in GMax - or a boat, cat (tricky), broomstick
or pair of boots - and put the MDL into any aircraft folder. Load the
aircraft in FS and it's the same old panel that pops up and the aircraft
will take off and fly just as it used to - but look at it from the outside
and it's a cat or pair of boots that you'll see sailing through the air.
You
need two files to create aircraft performance and you may find it confusing
because there are some changes in FS2004. As a result it is a hybrid development
and you will find some duplication and redundancy. In all previous versions
of FS the performance was controlled by values in the .AIR file. In FS2004
many of these values have been moved into the aircraft.cfg file. Unfortunately
the .AIR file has not been restructured from FS98 and the same values
are still present - but they are redundant.
The
.AIR file has to be copied from another aircraft folder because you cannot
create one from scratch. It may then be edited with a suitable program
like Flight Dynamics Editor or Aired It can be utterly baffling if you've
never looked at an AIR file before - and it plunges you right into aerodynamic
theory. It is one reason why designers opt out and "borrow"
the air file from an aircraft with similar performance. In my case I copied
the Sopwith file over to use on the Tiger Moth and modified it as necessary.
I only found out later that most of this work was redundant and that FS2004
only utilises a few of the aerodynamic formulae in the AIR file these
days.
Most
of the data that affects flight dynamics is now contained in the aircraft.cfg
file. This is a sensible move and will probably lead to a few new aircraft
performance programs emerging. To some extent FSEdit already does this
but it's output has been questioned a few times on the design forums.
It is certainly good for a "quick" rebuild of any FS98/FS2000
aircraft you port into FS2004. These will still have the minimal aircraft.cfg
file required by those programs but if you open this in FSEdit and then
save again the additional details are automatically included in the new
file.
Again
I will not dwell on the aircraft.cfg file too much. If you are serious
about creating an aircraft you will find all you need to know in the FSEdit
SDK - one of the many now available from Microsoft. It is not light reading.
|