'Using Rhinoceros' Discussion Thread

[wunwinglow]

Hi Steve,

Making a non-circular fuselage is just a matter of creating the appropriate frames to the right shape, and lofting between them. I chose a circular fusealge to speed things along, but I can certainly do a seperate 'how-to' if you like. Rhino has a bunch of excellent curve tools, like traditional 2D CAD, for just this purpose. One thing you will have to remember the quality of your original shape data, ie the drawings you are using to base the model on, have to be very accurate, otherwise the shape goes to pot!! It is usually at this point you discover the faults in apparently nicely drawn plans, which are actually no good at all. Ho hum....

Here is an example

Speak soon,

 

[arek93]

I create in Rhinoceros this:

PS.: Can be it?

 

[wunwinglow]

There you go! Provided all the surfaces are developable, you can 'unroll' each surface, export to a paint program for colouring, print it and make it!

Tim P

 

[arek93]

I know... But in paint? I want export to corel or Illustrator

 

[wunwinglow]

Sorry! I used the word 'paint' with a small p, ie software for making it coloured, not 'Paint'.... I agree, CorelDraw and Illustrator are much more appropriate for this sort of work. Don't worry, this aspect of making the model will be tutorialised very soon!! And I use CorelDraw v9.

Tim P

 

[RyanShort1]

I'm almost done with the first installment on
"painting" a model in GIMP...

Ryan

 

[57townsman]

Hi Tim,

Thanks for the reply! It is actually creating the appropriately shaped frames that has me stumped. Can this be done from multi-view drawings without section views? I have a gut feeling it can be done, but I'm guessing it takes a bit more work

Thanks again,
Steve

 

[wunwinglow]

It is actually creating the appropriately shaped frames that has me stumped. Can this be done from multi-view drawings without section views? I have a gut feeling it can be done, but I'm guessing it takes a bit more work

Thanks again,
Steve

Hmmmm. Brutal fact time!! It depends entirely on your design accuracy requirement criteria. If you are happy with a 'looks OK at arms length' kind of model, then even a 2D coloured silhouette can look very good, while a 1:4 scale replica down to the ASI makers name on the instrument panel, well, you need more data!

Realistically, you have to use the best you can get, for the purpose in mind. I find the research is half the fun, so I tend to try to hunt down really good drawings before I even think about designing a model. 40 years in the hobby collecting aviation magazines and books (remember them?) mean I have a fair selection already, but new stuff is always turning up! eBay; ooo, what a double-edged sword that site is....

Anyway, If all you have is a 3-view, you may well get away with a fairly simple model, especially if you have some good photo references as well. But, you are going to have to 'create' those sections yourself, and I find it is usually easier to work with 'real' details, dimensions, shapes, than to try a guess.

One word of warning. If you are looking for details on a particular aircraft, or anything else, ask around. There may well be excellent references available, or at least you will get a steer on where to look. You might also pick up warnings about duff gen, of which there is an awful lot! Just because it is on the Internet is NO guarantee of its accuracy or authenticity. I could tell you several horror stories; Airfix Fairey Battle, Aurora F2b Brisfit; I could go on.....

That was a few more than one word, wasn't it!

Speak soon,

Tim P

PS I'll start a 'creating sections' tutorial very soon.

PPS take a good look at pics of the real aircraft, and see how it was put together. Understanding that is a HUGE help in understanding the underlaying geometry.

 

[RyanShort1]

Better yet, look at the real thing! All the drawings of the Piper Tomahawk stink if you have access to the real thing... They just don't do it justice.

Ryan

 

[Gil]

Well said Tim.

An interesting fact of combining the computer, scanner and internet with the design process brings one to realization that what was once thought of as being accurate doesn't hold up to critical examination any longer. The best source of data is photographs. These can yield valuable detail data just not available in technical drawings. Case in point is I just found out that my current subject was flown with the starter handle hanging out the right side of the fuselage..., not to mention the side view which has the wing, panels, longerons and God knows what else in the wrong positions. I'll be OK once I get over the present case of reference blues. The digital micrometer is really coming in handy now. One other thing that needs to be added, this stuff takes time, sometimes a lot of time depending on how much detail and accuracy one wants in the finished prodcut.

One other question Tim, are you going to use UV mapping to wrap the fuselage?

Best regards, Gil

 

[wunwinglow]

Hi Gil, UV mapping? That means using bitmaps and meshes, and me and bitmaps don't see eye-to-eye...... If I can avoid them, I will. Don't worry, this is all included as part of the Tutorial 5 Year Plan!! But I will be using vector data, extensively, if that is a hint.

Tim P

 

[ripper]

Any progress soon?

Hi, wunwinglow,
your tutorial is really interesting - I have just laid my hands onto the Rhino, so I would like to ask, whether there will be any new parts of that tutorial?
Thx
-ripper-

 

[57townsman]

I think Tim's attention has been diverted again

Steve

 

[wunwinglow]

Yup, I've been a bit distracted recently; but I hadn't realized it was for so long!

Apologies, seasons greetings and Happy New Year to everyone,

Tim P

(the P stands for procrastinator, remember....)

 

[Jimi]

anyone here know how to draw panel lines on complex surfaces? (ie fuselage) in rhino? what i do, the extrude line then trim command though works, is very tedious and time consuming. And would it unroll accurately too?

Oh yeah, anyone ever thought of sheet metal design programs? unlike rhino, these programs DO include the thickness of the skin/ formers thereby simplifying the task of construction.

 

[wunwinglow]

Hm, depends. Rhino 3 is much better at unrolling surfaces than Rhino 2, so you can easily cut up the panels using planes or lines projected onto the surfaces. The unrolled panels can then be reassembled into the panel you want to cut out of paper. Alternatively, if the panel line is parallel ( or so close to parallel no-one will notice otherwise) you can offset one edge of the unrolled panel to create the new line. Alternatively again, you could just add the panel lines in Coreldraw or Illustrator after you have exported the unrolled surfaces. If you want some examples, let me know and I'll knock up a quick tutorial on the subject. Remember, use the approprite software for the job in hand; don't go making life difficult for yourself by using the wrong software!

Ref the material thickness, I just offset the outline of the ribs and frames by the thickness of the paper. I nearly always end up having to tweak it anyway, because the cutting, folding, creasing and gluing operations add at least as much variability in the final assembly as the thickness of the paper. Remember to account for any joining strips as well! And then do a test build. Or several......

Tim P

PS I just tried this in Rhino, and it is a piece of cake! I'll do some screen grabs over the next hour or so to illustrate the process.

 

[wunwinglow]

Panel Lines in Rhino

Here is a short tutorial on creating accurate panel lines on unrolled surfaces using Rhinoceros software. Firstly, prepare your model part. Here is a short section of fuselage created by doing a straight loft between a circle and an elipse.

Lofting gives us this sort of surface.

Moving to the side view, and perhaps using a bitmap background as a guide, the panel lines are traced out using the normal line tools. Remember these are being created on the construction plane at the moment, so watch your snap settings!

Using the project tool, the panel lines can be projected onto the fuselage surface. Make sure you are in a side view when you select the surface onto which the projection should be made. If successful, the newly projected lines will look something like this. Notice the original lines still on the construction plane inside the fuselage.

The projected lines can then be used to split (not trim!) the fuselage surface into several parts. You can now select these split parts individually like this,

and

You can now unroll each section of the fuselage, noting that the smaller section gets placed in its correct location relative to the bigger part.

and

You might want to rotate the unrolled parts so the centre line is vertical. Use the rotation, snap to end and ortho functions to do this accurately.

Then select the unrolled surface and export selected items as an .ai file.

Then import this .ai file into CorelDraw, where it can be edited, copied, coloured etc. to suit your design.

Hope this makes sense, comments always welcome!

Tim P

 

[Maurice]

Question

When you project those circles onto the surface don't you end up with a slightly egg (not eliptical) shaped object sitting on the surface?

(Not that it's really going to be noticeable)

 

[Jimi]

lots of thanks wunwinglow! this would sure make modeling a lot easier!

 

[wunwinglow]

Question

When you project those circles onto the surface don't you end up with a slightly egg (not eliptical) shaped object sitting on the surface?

(Not that it's really going to be noticeable)

Yes of course, but that is basic geometry. This tutorial wasn't intended as a primer for that! If you wanted a better-looking circle, you could either orientate the circle to be projected so that it was parallel, or nearer so, to the surface and project or extrude it. Simpler solution would be to replace the 'eggs' with circles on Coreldraw. Depends onhow accurate you want to be.

If you haven't got a good grasp of 3D Geometry, you are not going to make much progress with any of these programs. There are loads of websites that cover this sort of stuff if you have any questions about it. I'll list a few if anyone wants them.

Thanks Maurice for pointing that out.

Tim P