Workshop from Dietmar (Lego) Part 2
OK, let’s go with part 2:
With the same technique (just without multiple mirroring) I have built the stabilizer.
The tail rotor housing together with the pitch-lever can be build quickly.
Now we just miss the main rotor itself. To make sure, that the belt wheel will later rotate together with the
tail rotor the two parts must be in one object “Tail rotor”.
We will come back later to this.
To proceed with the tail-boom I need an undercarriage, because both are connected by a bar.
For the undercarriage we need a cuboid that overlooks the heli in horizontal. With the “Knife” we cut it a view times and “bend” the cuts. It is convenient to keep the SHIFT-Key pressed while rotating (the selected parts move in 15degree steps).
The skids are made out of a 12-sided cylinder that is cut and bend a few times at the ends.
The adapter for the skids on the strut is made by thickening the skid itself (“knife” four times and scale the middle ring with “Select > Belt”).
The support for the tail-boom is built from a 12-sided cylinder and an added cuboid at both ends.
An according counter-part of two cuboids with a little distance in between is added to the tail-boom and the skid-bracket.
I have “knifed” the ends for optical reasons and have allocated them do different objects. With this you can later define different materials for each part (tail-boom = CFK, Fixture = Alloy).
The servo-holder is also made from a simple cuboid that is “knifed” and tapered at the corners. You don’t need an opening for the servo. This would not be visible in the Sim.
Next is the rotor with the rotor-head, the swash plate and the many small push-rods.
At first we should think about which parts will later rotate. AFPD rotates everything that belongs to the object “Rotor”. In our case this means, that the main shaft, main gear, upper part of the swash plate, pitch-compensator, blade holder with levers and the fly-bar mechanics must be included in this object.
The rotor blades and the fly-bar itself are separate objects.
Only the “not rotating” part of the swash plate with the push rods to the servos is not included in this bject.
Let’s start with the fixed parts:
The swash plate itself is made quickly. It consists of simple cylinders with different diameters. The arms are built just roughly, because they are very small and the details can not be seen later.
The ball-heads are a challenging part on the first view, but they can be build with little effort. At first you need a cylinder as fixture for the push-rod; a thin cuboid that is 3 time tapered. Then we need an 8x8 ball, that’s it.
The ball-heads are then “mirrored” inside the object and moved to the according position.
The “rotor-object” is build according to the reference photo.
The big gear wheel is build as a ring with spokes and hub. Please do not make the single teeth. This is a time- and polygon-wastage. If you like you can later put a dark-light striped texture around the wheel.
The rest of the rotor-head mechanics should be build with little amount of polygons. I just have oriented roughly on the photo. You only need to take care about the proportions. Nobody will be able to measure the exact mass. It’s just about creating a visual effect of a turning rotor.
The pitch compensator is build out of simple cuboids; the levers are tapered on time. The fly-bar linkage is also just an 8-sided cylinder that is “knifed” three times at the bending. The bending consists of 3 polygon rings.
The only important point here is to include the fly-bar linkage into the “rotor-object”. If you would include it into the fly-bar object it would slowly disappear with raising rpm and this would create an ugly gap in the rotor-head. If you like you can also slit the blade holders.
The blades and the paddles are made quickly. They consist of primitive cylinders that are flattened. The blades are a little tapered at the outer end. This can be done by “knifing” them, downscale the rows of points towards the outside and move the trailing edge outwards.
I have also built the typical cap for the rotor head.
On the picture there are now 4 objects:
-Rotor (complete with gear wheel, upper swash plate, mechanics and fly-bar linkage)
-Paddles (Fly-bar with the paddles)
-Blade 1
-Blade 2
Altogether it looks like this:
Unbelievable, our model looks already very detailed and has just about 8000 polygons.
The next part is the tail-rotor.
It is the same procedure than with the main-rotor. First think about which parts will rotate. But because everything will be very small, you don’t need to spend too much effort for details.
The complete rotor shaft with the belt-wheel, pitch-lever and the blade holders are combined in the
“tail-rotor” object.
The blade holders are again 8-sided cylinders, not slit this time for the blades.
The tail-rotor blades are in the case of the “Crown III” very simple, because they have the shape of the main blades, just smaller and wider.
The easiest is therefore to copy the main blades, downscale them and adjust the width and form.
If the tail-blades have a different shape, we must build them new. Use the absolute minimum of polygons because you will not see any detail with the high rpm.
Together with the tail-rotor mechanics it looks like this:
We don’t need the drive-belt yet. If you use an open angular gear, you should include the angular wheel of the tail rotor shaft into the “tail-rotor” object. The other one is fixed on the tail-boom. As mentioned before, don’t build the teeth of gear wheels. This is done by textures.
Now we come to the RC-equipment:
Normally you don’t need to spend too much effort here, but at the “Crown” all components can unfortunately be seen very clearly.
To avoid using too much polygons we reduce the geometry to the absolutely necessary.
For e.g. the Gyro is just a primitive cuboid. The battery is a cuboid with rounded corners (“round” = 2), the receiver is a cuboid with an extension on the side. Only for the ESC I have spent a few more
polygons (only because I had one from a former project)
The essential part is here to get proper textures. The parts are very small and imperfect, that we can
count on the textures. Nice textures can be found for e.g. in some online RC-Shops.
I always use already textures standard-parts because I built them in advance and then add them to the models later (“File > Insert”). After a while you will have a nice stock of standard-parts.
The cables to the ESC must of course always being adapted to the situation. Therefore the formerly
straight cables are cut and bend several times with “Knife”.
The cable from the battery to the ESC can be skipped, because it is inside the canopy can not be seen.
The last detail we have to create is the belt for the tail-rotor.
Also here we want to use only the absolute minimum number of polygons. The problem is, that it goes around the belt-disc and therefore needs a lot of polygons, or?
Of course not! We built it as a mixture of geometry and texture!
Essential is here, that the belt is build out of a cuboid that does only tangent the belt-disc. The rest we do with a black texture.
We do the same at the tail-rotor; we just rotate the end of the belt 90 degrees (like in the original).
This procedure has the advantage, that we only need 36 polygons.
To avoid bad surprises at the transition from the polygons to the textures on the belt-wheels, we pull the belt a little further than the end of the belt wheel, so that they are overlapping a little with the black textures.
The arrow-marked polygon is the first one that will get the texture. The polygon to the right of it gets an alloy-texture. The belt should overlap a little with the marked polygon, so that later the alloy will not shine through.
Do the same for the tail-rotor.
