This might be very basics of shape generation for the advance modelers, but could help others understand better the finer aspects and appreciate good models from not-so-good or basic ones.

And this could very well be extension of DPV1's tutorial on "How to create sperical objects in 3DVIA"
( http://www.3dvia.com/blog/2009/03/05/3dvia-shape-tutorial-how-to-create-spherical-objects/ )

If we create ‘Front’ ‘Top’ ‘Side’ views of a cube, we get square geometry in all 3 basic planes. The other way round if we have these ‘square’ views we can generate the cube by extending the squares in 3d in 2 directions, say in X axis and Y axis. The intersection of these extensions would yield a Cube. 

Similarly, we can generate fairly complex shapes if we have accurate, scaled and perfectly placed views. 

In the first example, I have 2 circles of different radii. I project them to make 2 cylinders intersecting at right angles. Now, after removing the ‘unwanted’ surfaces we have a solid similar to say a soap-case.

2nd example has one semicircle and a ‘rectangle’ with 2 sides circular in nature. When both are extended to intersect, and I remove the external surfaces I get a shape similar to a F1 car’s rear-view mirror, or a pen box.

3rd example is pretty interesting, 3 equal circles in perpendicular planes. In first step you get a flowery kind of shape. When you remove the external surfaces, you get a spherical type of object. 

To build a more accurate sphere, all you need to do is increase the cylinders as explained in the 4th example.

Now, it’ll be easy for you to understand how the nose of “Sikorsky 92” model was made. Rather the whole of the chopper is made in this way. The original shape of the nose should be conical. However, in my model it’s more like intersection of the side and top views. So rather than being conical, it’s parallel to side and top planes. However closer to the actual cone if not exact cone!!

So the key is that you should be able to disintegrate the complex shapes into simpler parents. And when you can do that half the battle is won :)

When you have 3 views of any car or aircraft or any component you can develop the 3d model which would be fairly accurate when one sees it parallel to these 3 views. 

The starting point is basically a drawing like the one available at ( http://www.aviastar.org/helicopters_eng/sik_s-92.php ) for Sikorsky 92. You’ll find many such drawings at ( http://carblueprints.narod.ru/ ). Just google “blueprints” and you’ll land up with loads of such images… So happy modeling…