Between fuselage and wings - NURBS

[mrys]

There is my first tutorial, so if you find it not useful feel free to throw it away:D

In some posts by Kevjon he asked me how am I doing in Rhino wingtips and surfaces blend between wing root and fuselage. I decided to write this little tutorial believing, that it will be useful for someone else, who want to start modelling with Rhino.

Rhino is a modeler based on NURBS technology. It is very fast and not too expensive soft - also consuming not to much computer resources. In my opinion it is one of the best modeler ever create!

Typical for NURBS curves and surfaces are mathematical construct and has some limitations. For example in one surfaces it is impossible to get sharp corners. For us it is mean, that we can made wings only as two part: top
and bottom. After joining we have multisurface.

In my practice I use method, which based on real panel lines of airplane. It is mean, that I always try to place cross sections in exact position and divide "subject" as in real world. My ideal is to build whole aircraft from panels, but it is not necessary.

Let's see Hurricane...

367

And how it was made?

Let's see...
368

Here we have fuselage on blueprint (in thic case it is imported vector from Illustrator, but it has no meaning). Based on them I draw lines described wing profile near root part and line of blend surface on fuselage. After that by command Surface->ExtrudeCurve->Straight I made cutting surface.

369


Now we have fuselage with "hole" and we can get curve for our blend by Curve->CurveFromObjects->DuplicateEdge Setting up rest curves and... need additional profile for blend surfaces. Usually I try to draw it and bending, but also have another method.

370
371
372

Curves on Img.6 screen was made by projecting them onto fuselage and wing surfaces. Now we can get profile curves by blending them (Curve->Blend Curves)

373

Most of them needs correct, but gave very flows result. We should use not to much of them - only one or two, just for good result.

And now final.

By curve network - 374

or Sweep2Rails - 375

As we see more accurate results gave us curve network.

My way give not always good results. It depend on unique model and... quality of blueprints. Sometimes I have to join few ways for getting correct element.

And of course it is only my way, for you maybe not useful.

376

[kevjon]

This is great mrys. Thanks for taking the time to put this together. I am currently working on the blends and fillets between fuselage wing/tailplane and fin so your mini tutorial is very timely and helpful.

I'll give this a go and see how it looks.

[Bigtodd]

Hey great idea on the curve network. I would have never thought of creating the intermediate curves. This is one I will try out. What is your method for the fuselage? do you create small sections and then us the surfaces to help control tangency? Or do you try and use all of the cross sections at one time? wich commands are you using mostly; the loft command, or the curve network command, or the birail command?

Any tips would be great. Some times it is hard to use Rhino by yourself.

Thanks

Todd

[kevjon]

I think you'll find in most cases it is best to use curve network for fuselages.

Draw the top and bottom rails of the fuselage in side view. Draw one side rail in plan view and then mirror for the other side. Draw all your cross sections. Then use curve network by picking top & bottom rail then side rails and then cross section curves front to back or back to front.

Give it a try, I'm sure you'll see how easy it is.

[mrys]

Hey great idea on the curve network. I would have never thought of creating the intermediate curves. This is one I will try out. What is your method for the fuselage? do you create small sections and then us the surfaces to help control tangency? Or do you try and use all of the cross sections at one time? wich commands are you using mostly; the loft command, or the curve network command, or the birail command?

I agreed with Kevjon: curve network is used mostly, because giving you the best control about shape you build. Sometimes better is to use birail, but it depend on unique model. Tu build whole fuselage in one pass is very hard, but once again it depend on model. For MiG-15's kind of aircrafts it is easy, but for Mustang not . Much better is to divide fuselage on parts based on curves. In this method you can use more curves only in this places, where you really need them more. For example hole for cockpit in Hurricane and many other should have (looking from the top) parallel edges. So you can use this edges (as curves) in curve network. Etc, etc.

Hard truth is, that everything need practice. When you will working with Rhino you will discover many ways to find best solution for your problem.

Oh, almost forgot. I've never used control tangency for surfeces. Most accurate efects I get by using only profile curves.

[scrimski]

Curve netowrk is great for that. I wonder if it would be better, look more realistic when modeling the whole plane from different panels instead of lofting or sweeping 2rails from spants(?). In theory this should be possible, but it depends on the quality of the prints I guess. Gotta try out this when I have some spare time.

[kevjon]

Pretty difficult to set up the curves accurately enough to model the whole plane panel by panel. Some seriously skilled drafting involved. Easier to model it as whole shapes eg fuselage, wing, wing fillet etc, and then split them up into individual panels. The beauty of splitting them up into individual panels is that you would get a very clean mesh because the mesher doesn't have to deal with the joints between nurbs surfaces. The renders should look pretty good too. I'm planning to try this if I can't get a good mesh after joining all the nurbs surfaces together.

[roshent]

And for your curves use Curves>free form>Interpolate points. With this curve I think you get maximum control over your curve with as less distortion possible. Because you can draw the line over your blueprint and when the curve is created you have a control cage with knots around it to mainpulate to your hears content...

[mrys]

Curve netowrk is great for that. I wonder if it would be better, look more realistic when modeling the whole plane from different panels instead of lofting or sweeping 2rails from spants(?). In theory this should be possible, but it depends on the quality of the prints I guess. Gotta try out this when I have some spare time.
Pretty difficult to set up the curves accurately enough to model the whole plane panel by panel. Some seriously skilled drafting involved. Easier to model it as whole shapes eg fuselage, wing, wing fillet etc, and then split them up into individual panels. The beauty of splitting them up into individual panels is that you would get a very clean mesh because the mesher doesn't have to deal with the joints between nurbs surfaces. The renders should look pretty good too. I'm planning to try this if I can't get a good mesh after joining all the nurbs surfaces together.
Modelling from individual panels, as real plane was build is only a mind idea. In fact, especially in older machines surfaces are not ideal, curvature is not perfect. Even using this method I think, that it would be better to build airframe as usual - by curve network for example and after that divide it for a panels.

But I would rather use this method to get proper shape of panels, that are lie on two or more surfaces. Let me show you this idea on MS.406 example.

382

On this image you see model on blueprint and curves to build blend surface between fuselage and wing (yellow lines). But in fact real panel has different shape (green line).

If we stop in this stage we would get this effect:

383

Sharp, visible line is ugly for me, so let solve this problem. By projecting real panel shape on model we can cut place for new one and get the line of contour.

384

And here we have new surface without dividing line, based on new curves.

385

And final effect

386

[mrys]

And for your curves use Curves>free form>Interpolate points. With this curve I think you get maximum control over your curve with as less distortion possible. Because you can draw the line over your blueprint and when the curve is created you have a control cage with knots around it to mainpulate to your hears content...
I never use Interpolate form curve... I start wit simple 2point line, then rebuild it (Edit>Rebuild) wit 4 points and try to match exactly with blueprints. If it is impossible I rebuild it once again with 5 points (step of only 1 point every time). It gives me good line with fewest possible points. And General Rule is: less points - less problems.

Have to corect my post: sometimes I'am using Interpolate point Curves, when need to draw top, bottom ora side profile on existed crossections. Then this kind of curves are best and easy to use.

[kevjon]

Posted by mrys
But I would rather use this method to get proper shape of panels, that are lie on two or more surfaces. Let me show you this idea on MS.406 example.

This is a really great idea for modelling all the individual panels of a aircraft in Rhino !
It is kind of like modelling the plane twice but the end result could be quite good. Will experiment with it.

Posted by mrys
By the way one newbie question. How to place attachemented thumbnails in correct position, not all together in post? It would be better for use then writing "Img.1, 2, 3" etc....
Probably best to combine all the seperate images into one or two larger images and arrange in the sequence you want them with a number for each step.

[mrys]

Probably best to combine all the seperate images into one or two larger images and arrange in the sequence you want them with a number for each step.

As you can see in previous posts I found the solution.:D

[Skyraider3D]

Great stuff Marek.
Love your Ms 406 model :)

[FelipeBelalcazar]

Hi guys, i'vebeen modilling for a while and just now got into max... i was wondering if there's a way to pull this off in Max 8? the way i used to do it on my pre-max days is too complicated and was wonderingif there was a better way...

thank you mrys for this awesome tut, you are a very skilled modeller ive followed your work for a while.... the hustler is one of my top favs :)

gracias!

[kevjon]

Max's nurbs are pretty bad and so is its ability to convert nurbs to polygons for uvmapping and rendering. If you want to model with nurbs your best bet would be to buy Rhinocerous or a cheaper alternative is MoI.

[Skyraider3D]

Marek's current models are all done in polymodelling, I believe, despite his many years experience doing NURBS. That in itself says enough about the "success" of NURBS for this kind of work. At this moment in time, polymodelling is the most popular and flexible modelling technique, despite its quirks.

[kevjon]

Marek's current models are all done in polymodelling, I believe, despite his many years experience doing NURBS. That in itself says enough about the "success" of NURBS for this kind of work. At this moment in time, polymodelling is the most popular and flexible modelling technique, despite its quirks.


Sad but true.

[mrys]

As Ronnie said, I'am using polymodeling now. NURBS are really fantastic and flexible if you don't need to UV them and texturing. Making holes, dimensional precision are really cool using NURBS but in fact any good renderer need to "mesh" your model. And then NURBS are not as friendly as before. I have few my old models and still think about transfering them into "poly" version. But still didn't found good method for this.

I had some problems during my transfer from NURBS to polymodelling they are very different methods. But need to say, that I feeel more modelling freedom now.