Ivan's Workshop - AF99 Tutorial - C205 Veltro

Exhaust Stacks

Aircraft Factory 99 at times appears to be an unfinished application. There are some really strange behaviours and we are about to describe one of them.

The Exhausts on the Veltro can be easily built with AF99 Structures. In fact, it is one of the few things for which using a Structure isn't a great compromise in the object's shape.

As you can see from the First Screenshot, Precise locations aren't terribly important to start on any Part you are building. I generally start with a freehand outline that has the same general shape and number of points.

Refine the Part's shape and location with the Point Editor. The dimensions are scaled from the reference drawing. The finished Side Template is shown in the Second Screenshot.

Note that for Left / Right Pairs of Structures, you really don't need but one Side Template on the CenterLine of your model. When using Structures for the Main Wheels, I put a Side Template WITHIN each Wheel because when referencing a Structure, the Side and Top Templates will also show. A Wheel outline at the center of the aircraft would be distracting.

The Top Template should be located within the Side Template. Again, this is to avoid distracting Templates floating well away from the part. There is no reason not to do this as there might be for the Side Template where one will serve both sides.

In the Third Screenshot, The inboard edge of this part is set to be slightly inboard of its contact points with the Cowl. The outboard edge's location is determine by dimensions from the reference drawing. When this part is finished and saved, Rework / Mirror it to create the Right Top Template.

The Fourth Screenshot shows the Cross Section selected for these parts: A Rectangle.

The Last Screenshot shows the result from the Structures Shop. The same needs to be done for the Right Side Exhausts.

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A Drop of Glue for the Exhausts

We know the inboard edge of the Exhaust Structures follow the Cowl / Nose outline pretty well. Use them as a reference to create the Exhaust Glue Parts. Again, when done with the Left Exhaust Glue, Mirror it for the Right Exhaust.

In the Assembly Sequence, Select BOTH Bulkheads.

Now HERE is the strange issue:

The Colour selected for a Regular Structure such as the Spinner will be the actual colour of the Spinner in the Simulator. When Bulkheads are selected, The Colour selected for the Piece will be that of the Bulkheads themselves. The Colour of the Piece in the Simulator will be the GROUP Colour....

Think about that for a bit. In our case it won't make much of a difference because this piece will be textured, but still this is strange behaviour.

- Ivan.
 
The Spinning Propeller

My Aeroplanes typically represent a spinning propeller with a transparent triangle shaped "Blur" that is intended to look like the spinning propeller blades one sees in photographs. Creating such a "Blur" is relatively easy.

The First Screenshot shows the beginning part that is an import from the Storehouse. A 24 section circle works well for either a 3 blade or a 4 blade propeller.

Rotate this 90 degrees to face it the same direction as the Propeller. Center this at the same location as the Propeller's Center and then resize down to the same diameter as the Propeller.

Next, in each "Space" section, put one point at the center (0.70 Up) and delete the other points that are not needed.

The Second Screenshot shows the result.

- Ivan.
 
Canopy Frame Detail

These two screenshots show some detail that I should have included earlier. There are 3 Canopy Frame Component that are currently in use.

The Front one is obvious. It is Bright Green and can be seen in contrast to the rest of the Parts.

The Left and Right sides each have their own Components. As an example, the CanopyFrameL Component contains ALL of the Left Side Parts PLUS two rows of Parts from the other side. Thus there is an overlap of Right and Left Side Parts at the top of the canopy.

The Glue Part is connected to the Cockpit Sill on that side and extends one row over to the other side on top. I tried moving the front Glue point inboard, but while it improved the bleed from the front, it did not entirely eliminate it. Instead it caused parts of the Canopy Frame to disappear when viewed from the rear and slightly off to the side.

- Ivan.
 
Horizontal Stabiliser Part 1

Every once in a while, the dimensions listed in a drawing appear to be impossible to realise in a 3D Model. This is one of those cases.

From Drawings, the vertical location of the Stabiliser is at 1.50 Feet Up. This means that the fixed portion of the Stab intersects with two Polygons on the TailCone Component. Because I know I will be looking at these Parts over and over again, I put these two Polygons along with the reference Parts all into a single Component.

Dimensional drawings show the thickness of the Fixed portion of the Stabilser to be 120 mm which works out to 0.394 Feet. The thickness of the Elevator is listed as 72 mm which translates to 0.236 Feet. Several attempts to create an Airfoil shape with these dimensions failed to produce anything reasonable. There were always concave sections. The Airfoil shape shown here is a bit more involved than most with the 120 mm thickness retained but pretty much ignoring the 72 mm value.

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Horizontal Stabiliser Part 2

Part StabLT02 is the most critical Part because it determines many other dimensions in the rest of the Component. Just about all the other parts are related to this one, so we will create it first.

The First Screenshot shows a Top View of the first Stabiliser Part as connected to the reference Parts.

The thickness of the outboard section of the Stabiliser is not specified, so we just pick something that looks reasonable. The Second Screenshot shows the section of maximum thickness being adjusted.

The Third Screenshot shows the outboard edge of this Part being adjusted to line up with the inboard edge. There is generally a bit less angle on the outboard edge because the sections tend to be thinner. In this case, the front and back of this edge only differ by 0.01 feet whis is the least we can do.

The Fourth Screenshot shows Part StabLT01 being created. From front to rear, this part is level.

The Fifth Screenshot shows the forward edge of this Part adjusted to correspond to the Leading Edge of the Stabiliser Outline. When this is done, there is a pretty good chance that when viewed from the front, the front edge of this Part won't be a straight line anymore and it wasn't. The Point Editor should be used to adjust the points vertically to align with the back edge of this part. A screenshot here would be pretty much meaningless because in order to show the detail described, it has to be zoomed in so much that it doesn't make much sense.

The Sixth Screenshot shows the Inboard Edge of Part StabLT02 being adjusted to meet the TailCone. Note that from a side view, the top edge of the Stabiliser is roughly 2/3 of the way up on the TailCone polygon, thus the edge is 2/3 of the way between the sides of this same polygon when seen from the top. When adjusting the front edge, try to maintain the sweep of the part by moving the inboard point slightly forward.

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Horizontal Stabiliser Part 3

The Leading and Trailing Edge Parts of the Stabiliser are trivial to create. They connect the two central parts and the outline of the Stabiliser. Note that there is a small step between the Elevator and Fixed Stabiliser. This was a concession to the difference in thicknesses.

After doing just the TOP Parts, I decided to check the contours and built a component made up of only Top Parts. The result was not quite what was expected. Note that the side of a polygon which displays is the one that faces outward from the center of a Component. The is not a great concern yet.

The center parts for the underside of the Stabiliser are created from the corresponding upper parts with a point editor. The Centerline is at 1.50 Up, so we just calculate how far up the point goes and then make it the same distance below the centerline. Thus if a point is at 1.64 Up, it is 0.14 Up, so we move it to 0.14 DOWN and get 1.36. Note that because the thickness is 0.39 Feet, Parts may extend to 0.20 above the centerline but only 0.19 below the centerline.

As expected, using both the upper and lower Stabiliser Parts results in a reasonable looking Component.

A Glue Part is needed for each Stabiliser to connect it to the Tail Cone. This is done by referencing the inboard side of the Stabiliser. When the Glue is created for one side, Mirror it for the other side.

Time to get ready for work.
- Ivan.
 
Status Update 20110705

This is the current status of the Veltro. There are a few pieces that have been built that do not appear here yet, but that is because I am currently working on the nose section. The current Component count is 14 which still leaves a bit of room for editing.

As might be expected, there is a bleed of the Aft Fuselage through the bottom of the Radiator, but the solution to that depends on how much is left over for resources after the essentials are done. Some things MUST be done with Components and those should be done before the things that are easiest to solve with Components.

Also, Please remember that although this is the current status, some pieces probably won't look exactly like this by the time everything is finished.

There is a lot that can't be seen with just a simple screenshot. If anyone is very curious, email or PM and I can send a copy of the MDL file as it currently stands.

- Ivan.
 
Supercharger Intake Part 1

The Supercharger Intake on the Veltro is a fairly complicated assembly. It is flat on the top and bottom. It somewhat follows the contour of the cowling panels. It is extremely long.

From the dimensional drawings, its outboard edge extends to 625 mm (2.05 Feet) from the centerline of the aircraft. From measurements from the drawings, its radius is 0.32 feet at its greatest.

The First Screenshot shows a simple profile of the part as measured from the side view of the aircraft. The actual piece on the aircraft does not follow a consistent line from front to rear, so it has been modified slightly so that it does. The height of the center line in the drawing is from 1.10 Up to 1.13 Up. I chose to make it consistent at 1.11 Up.

The Second Screenshot shows the first try at creating cross sections. I used the 10 point circle imported from the storehouse. This was rejected.

1. I had intended the texturing to be Left-Right but in looking over photographs of the actual aeroplane, I realised this probably would not work well. The top and bottom of this intake are flat and there are distinct textures on the top that cannot be done unless texturing is Top-Bottom.

2. The extreme outline of a "Round" piece is best determined by a peak / point at that location rather than a flat. Thus if the side view were to look good, the top and bottom of this Component should have sharp edges.

3. Because the top and bottom of this piece is flat, to show a gradual curve, one should have a peak at the top center rather than a flat. The extension of a peak at the centerline to the Cowl looks better if it starts at the mid point.

4. The Top-Bottom texturing is best done with an edge dividing top from bottom.

5. A single line at the centerline when viewed from the top and the side allow us to align the cross sections better.

With these requirements, the choices were to either use a 8 sided circle or a 12 sided circle for cross sections. The 8 sided circle just looked a bit too crude to use. Perhaps we will be back here to scrounge polygons if run out of resources.

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Supercharger Intake Part 2

The creation of the cross sections is extremely easy:

Import a 12 sided circle from the Storehouse.
Rotate it 90 degrees Yaw
Magnify (Reduce) it by 0.1 which makes the Part have a 1 foot radius.
Store this template part which I called X1.
(It is discarded after the cross sections are completed.)

For each cross section, start with X1 and Magnify (Reduce) it to the radius needed. (The largest radius is 0.32 feet.)
Locate the Part in its correct longitudinal location. Don't worry about vertical and horizontal alignment here. Just get it close.

Create two reference lines that hit the corresponding vertices from the top and side. As you can see, these lines are not quite smooth to start. The selected point on the top view is the location of the widest cross section. If the radius here (0.32 Feet) is added to the center location, it should equal 2.05 Feet which is the furthest outboard dimension.

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Supercharger Intake Part 3

The First and Second Screenshot show the finished locations of the reference lines.

Once those are resonable, each cross section is relocated by opening the part and using Control-Click to move its center after putting the cursor on the centerline....

The Third Screenshot shows all of the relocated cross sections.

The Fourth Screenshot shows just one row of Parts created. The location of the flat parts on top and bottom of each section is TEDIOUS. That took me around 1.5 hours to do.

When doing the assembly in the Component Shop, consider the display order. There are nine rows of Parts. I chose the following order: 5-3-6-7-8-9-1-2-4. There are no bleeds that I can see as a result.

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Supercharger Intake Part 4

The screenshots here show how the piece looks in the simulator attached to the Nose / Cowl section.

Good Day.
- Ivan.
 
Putting It All Together

With all the Pieces we now have, Here is what it looks like assembled.

The first two screenshots show that the assembly looks pretty much as intended.... From THIS angle. The intention was to put the back part of the Intake into the Fuselage section which would remove the largest bleed here.

As the next two screenshots show, there are a couple serious bleeds. The majority of what is showing is actually quite easy to fix by cutting off the back end of the Supercharger Intake and putting it into the Body,Main group. The BIG problem which is barely noticeable here is that the group glue between Body,Main and Nose is at the origin (0,0,0) and being even slightly forward of that shows the Nose pieces.

Note that if we cut the Supercharger Intake straight out from the Cowl area, part of the section associated with the Nose would still show from this angle. We cannot cut it diagonally because the part that would show would vary depending on how far away from the aeroplane we were viewing from. The bleed isn't very large, but there is no real solution either.

- Ivan.
 
Inner Wing

Here is an attempt to move the Intake and Exhaust pieces to the Inner Wing, Left group. The result looks much worse at the moment but mainly because the process isn't complete.

Now folks might be wondering why not just throw all these pieces into the Body,Main group? The reason for that does not show up in these screenshots yet but will very shortly:

Remember that there was a very complicated assembly process starting with the Pilot. The Intake needs a similar though less complicated process as soon as the Intake opening and fairing areas are added to the front. Adding those is much more difficult if they are all in Body,Main. Note also that although the Oil Coolers are not added here, they may also influence things.

There is also a bit of an issue in that I need some pieces in the Nose group to address a goofy feature with AF99 models flown by AI.

The Second Screenshot here shows the change with the Nose Component moved to Body,Main. Note that I have also added a Template Part to separate Fuselage to Left Wing. This is a special part which I will explain later. There is no point in showing it here yet because I am still adjusting it. Note that the Nose blocks the Right Exhaust even though it should not in a real aeroplane.

- Ivan.
 
Wing Construction Part 1

Wings are very easy to make in AF99....

A very peculiar feature of the Macchi C.205 Veltro (and also the C.200, and C.202) is that the Left Wing is 200 mm (Just under 8 inches) LONGER than the Right Wing.

The dimensional drawings I am using are very useful in some areas but in others, they do not label fairly critical dimensions.

Dihedral is not labeled but it can be infered from the location of the Wing Tip in a side view (assuming the side view is correct). (Typical Dihedral for single engine fighters of this era is 5-6 degrees.)

The angle of incidence at the Wing Root can also be estimated from a side view. Estimating the angle of incidence at the Wing Tip by this method is too imprecise.

The First Screenshot shows the boundaries of the wing outline. The drawings specify the Wing Tip Chord as projected to the end of the Wing Tip as 1160 mm (3.80577 Feet so we use 3.81 Feet). The actual Wing Tip Chord is really specified at the last parallel section of the wing tip without the rounded end. The Wing Tip Thickness is specified as 77 mm (0.25262 Feet). What is also shown here is a Wing Tip Outline which is our approximation of the wing tip shape. We will revisit the Wing Tip later.

Problems:
Although the Taper of the Wing is specified in great detail, the SWEEP of the wing is not. It was approximated from a Top View. The problem though is that the Taper of the Wing in the Top View does not quite agree with the dimensional drawing though it isn't off by much. Also, the Thickness and Chord of the Left Wing is given but not of the Right Wing.

The Second Screenshot shows the Right Wing Template viewed from the front to show the dihedral angle. The Left Wing Template is also shown. My assumption is that the dihedral angle is the same which means the Wing Tips are not at the same height.

We already built a Wing Root Template (Wing Root Station) some time back. Here we will use it to build the Wing Tip Station. Compare the Chord at the Wing Root and Wing Tip. In this case, the Wing Tip is just over 65% of the Wing Root. Magnify / Reduce the Wing Root Template by a touch less than this. I used 0.64.

Move this new template out to the wing tip. You will likely notice as I did that the the angle of incidence of this new Part is too high. The reason for a slightly greater reduction than the numbers call for is to allow a little room to adjust the points of the leading and trailing edge to match the wing outline. A greater taper at the wing tip than the wing root looks better and takes care of potential rounding errors in the Magnify / Reduce step.

The Wing Tip Station probably has way too much thickness. Adjust each point Up or Down ONLY to correct this. The Fore-Aft location should remain the same because it keeps the alignment of the actual wing parts on a constant taper from root to tip. On the Veltro, the Wing Root is about 18% while the Wing Tip is only around 7%.

The Third Screenshot shows the resulting Wing Tip Station.

The Fourth Screenshot shows what can be done as far as introducing Wash-Out / Wash-In by pitching the Tip Station down (This picture shows 5 degrees). This is just an illustration for demonstration purposes. I intend NOT to make this adjustment.

Typically Washout on a wing is used so that the Tip / Aileron area stalls last on the wing. The stall at the root would cause turbulence to warn the pilot of impending stall but the unstalled tip lets the pilot keep lateral control as long as possible. The Japanese A6M Zero has noticeable washout when the wing is observed from the tip.

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Wing Construction Part 2

Now that we have all the reference parts we need, it is just a matter of connecting the dots to create the actual Parts to be used in the aircraft, but sometimes a few adjustments are needed along the way.

The First Screenshot shows the leading edge wing top Part. The problem with this Part is that it isn't even close to Planar. That means that it will tend to disappear when viewed at shallow angles. This Part needs to be triangulated with the highlighted vertex removed.

The Second Screenshot shows all of the Right Wing panels created in a similar manner. Note that some sections needed triangulating and some did not. Note also that I moved one of the points on the Wing Tip Station from 0.09 Aft to 0.10 Aft to match the Wing Root Station. It isn't necessary to have different pieces line up like this, but it makes checking things easier.

Looking at the resulting parts shows that some of the contours are not quite as expected. I want each of the 7 sections of the wing to be distinct and some of the angles are too steep to work that way. Thus a couple points at the upper leading edge of the Wing Tip Template were raised slightly as shown in the Third Screenshot.

Looking over the sections again I see a minor contour problem around the highlighted point. This point was raised yet again as shown in the Fourth Screenshot.

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Wing Construction Part 3

Attached are screenshots showing the result in the simulator. The wing looks a bit short in this view, but the dimensions are correct as far as I can tell.

- Ivan.
 
Wing Tips Part 1

We have seen the Wing Tip outline before. The First Screenshot shows a Part that is used to align the points of that outline. The idea is that we have a line from the Leading Edge of the Wing Tip Station to the extreme tip and another from the tip to the Trailing edge of the Wing Top Station. Each point on the Leading Edge of the outline must align as closely as possible to one line and each point on the Trailing Edge of the outline must align with the other reference line.

We can also use this method to create other Wing Tip Shapes. The F4U Corsair has a noticeable flat section on the underside of its wing tip slanting upward as it goes outboard. The Second Screenshot shows the results of this same method as used on a Corsair model.

There are a lot of things that can be done here using different kinds of reference lines. The Macchi C.205 seems to have a relatively simple Wing Tip that is in line with the Wing.

The Parts for the Wing Tip are trivial to create and add to the existing Wing Right Component.

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Wing Tips Part 2

The First Screenshot shows the entire Right Wing including the Tip in the simulator. Note that there is a slight sparkly line at the outboard trailing edge. Seems like there is a problem.

The Second Screenshot shows the misalignment of Parts that caused the bleed.
This was caused by changing the Wing Trailing Edge to align with the Wing Tip outline and then neglecting to change the Template Parts to match everything else. When the old Template Parts are used for reference, we get this. Note that the misalignment was only 0.01 Foot.

Fixing this was trivial and the appearance wasn't noticeably changed other than the absence of the bleed.

- Ivan.
 
Left Wing

I don't know if the wing tips on the Veltro are really mirror images of each other, but in our case, they will be. The extra length on the Left Wing is gained by moving the Wing Tip up 0.05 Foot and Outboard by 0.65 Foot. This works out to a fraction over 198 mm, but if it is 0.66 Foot, it would be equivalent to a bit over 201 mm. Either way, the dimension will be around 1.5 mm off.

None of the Parts from Left to Right are true mirror images because the Wing Tip Parts will all be moved and the Wing panels are all extended by 200 mm. The Dihedral angle will be maintained so that Landing Gear, Cannon, and such will mount in about hte same place.

After Mirroring the Parts and moving the Wing Tip outboard, we get the configuration in the First and Second Screenshots. I have looked at literally hundreds of pictures of the actual aeroplane and am still surprised at the degree of asymmetry.

Extending the Wing Panels and adding Oil Coolers results in the configuration in the Third Screenshot.

With the right tools, the process is very quick. Even through AF99, the process is tedious but not difficult.

At this point, the total resource count is 19 Components of 30 allowed and 894 Parts of 1200 allowed.

- Ivan.
 
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