Scratchbuilding a 1/20 scale F1 replica: ICEM SURF iv

After 35 more tries, I've got a Class A solution and I don't like it because:

1) It's explicit
2) It's hard to work with

Rocking out to Cherub - "Doses and Mimosas"

Take the two spots where the sides are visually straight

Put a couple of straight lines there

Put a couple points on these lines at a ratio of 0.5

Make straight lines using these halfway points

Couple of verticle lines using the same points

Couple of sweeps

Hide all the lines and blend

Make symmetrical, hide initial support surfaces

Another blend

Hide the support blends and extrapolate from an edge

So check this out. Connection checker

Catia says it's G3.

How about we hide the blend and just look at the extrapolate from above.

Now you see it

Now you don't

Because that extrapolation is perfectly straight vertically. It's not hidden as can be seen in the tree

Ditch the extrapolation, we don't need it. Now the fun begins

If you hit control points, it will create another surface. Let's think about what we actually see here. The first control point represents point continuity, G0. The second point tangent continuity, G1, as it's exactly verticle in the z direction to the first point. The third control point represents curvature continuity, G2 as it is the third point exactly verticle and evenly spaced in the z direction. Lastly is the fourth control point, evenly spaced, verticle in the z direction from the other points, acceleration continuity, G3. Neato.

Notice that same level of continuity is not represented in the x direction using this method

So if I extrapolate in that direction, I'm not going to like what I see

G3 continuous? Yes, but hardly what I intended. So lets get the the insanely hard non-parametric work.

I need four control points perfectly spaced in a line at the start and finish in the z direction

I'm going to snap this stuff to points I create. This is going to take forever

First a couple of infinite guidelines on a plane at a height of 500 (the same as my earlier sweeps)

Yeah so, below we can see that the plane is the same height as the sweep profile line

Here are my points recreated on this plane. I suppose I could have done everything from the beginning on a movable plane, oh well

Couple infinite lines

Actually, now that I think of it, this is going to be rough working with mathematically. Crap. Because I put points on a line with a ratio. Ditch this idea. Restart without the ratio. I need to know exactly where the x points are. Ugh.

This was the point that was going to be problematic. Now set to x=-200.

I'll just recreate all those support surfaces quickly.

Alright there we go. So next order of business. Click on control points, I'm going to need the max that Catia v5 has to offer in the v direction (trust me, I've tried 36 times)

Select the surface, click on control points, right click on Nv:7

Select 16. Catia automatically harmonizes 16 points in the v direction

My shape starts at x=-200 and ends at x=-2000. Difference 1800. 1800/16=112.5. There is a control point in the v direction every 112.5mm.

That's a bunch of nice, evenly spaced points, 112.5mm away from each other

What I've done here is make a line from the this row of points up to the infinite lines that I want to use as my guides for creating G3 continuity.

Now made points at a ratio of 1 on these lines.

Crap. Should have divided 1800 by 15 = 120. The points should be spaced by 120. Oops. Reworked.

Anyways, we can see this now pretty much lines up.

Alright so check this out. The end points are fine, they must line up due to G0 (point) continuity. Start from the second one.

Selected all eight points in that make up the G1 control points in the v direction