Autocad error messages

[cuwaert]

Hi, I had the audacity to start modelling a modell airplane using Autocad 2008. I know autocad isn't the wright application to model reasonable complex shapes as airplanes but because of some familiarisation with it I took the challenge.

I carved the first halve of he fuselage using slicing a rectangular solid.

I tried to fillet the edges but I get all kinds of error messages I don't find in the manual. this one for instance

Modeling Operation Error:

Spring curves do not intersect.

Failed to perform blend.

Don't know what a spring curve is or what the problem is.

I'ts also very tedious to select all edges of the many meshes, is there no way to just select the complete edge of a solid?

[Coosbaylumber]

Could be due to accuracy.

 

But if it "Looks" like it should go where shown, and you intended to make it go there then OK.

 

But, usually that sort of error message is because the endpoints to not (now) touch one another properly. Grab on to the end point of one line and move it over to the other point. Your UNITS or settings may say same point, but way down in the accuracy bin at like 1/10,000 or 1/100,000 setting they may not be. Or can be due to some Z factor. But simply try and move it even it they look and measure the same.

 

 

 

Wm.

[cuwaert]

or this one

Modeling Operation Error:

Cannot find mitre details where open sheet ends meet.

Failed to perform blend.

Failure while filleting.

 

Allso on filleting.

Cannot find the message so don't know what's happening.

Error messages are essential, where can I find them and their explanation

[kencaz]

You might try lofting your profiles, (or ribs). This can give some pretty good results.

 

Here is a lofted wing section:

 

 

 

KC

[ReMark]

You're right. Modeling airplanes in plain AutoCAD can be a challenege. Maybe you would benefit from the following.

 

http://www.cadtutor.net/forum/showthread.php?t=40872&highlight=airplane

[kencaz]

Add a fuselage:

 

 

Put them together:

 

 

 

 

I think AutoCad is a great tool to model your scale aircraft with...

 

KC

[cuwaert]

Thanks for the replies, they are very helpfull even when they don't directly solve my problem.

My first approach to model the fuselage was using loft with guides.

Again a number of problems arised (specially with the guides).

Error message " Invalid selection" without telling what is actually wrong blocked this approach. I had 3 guides to loft the rather complicated section around the nose (front section engine intake).

If I selected just one of the 3 guides, no matter which, it worked, 2 or 3 didn't (invalid selection). After checking and trying I abandonned the approach and went to the slicing method.

Before I did that I tried the filleting on a simplified version (just outer contours of the fuselage) and it worked. On the final version with slightly rounded upper and lower surfaces it didn't.

 

Software is a very nice thing, it promises heaven on earth and demonstrates with simple non realistic things and costs a lot of money.

The problem is that once you try the real stuff it often seems asif you get at the end of it's features before your work is done. Question is if that's true or do you just need to learn more or do you have the wrong application.

[ReMark]

Without a sample of your work it is difficult to say whether you need to learn more (bad technique?) or your using the wrong application (although kencaz has clearly demonstrated even the nearly impossible is indeed possible).

 

Just keep at it and refine your approach.

[nialb]

Try this for modelling aircraft wings - http://www.profili2.com/eng/default.htm

 

Stefano has also brought out a package for modelling fuselages which can be downloaded free for evaluation.

[Cad64]

Sure, you could do this in Autocad, but you will have to work a lot harder to do it. A program like Inventor or Solidworks could do it much easier and faster. Or programs like Rhino or FormZ or 3DS Max or Maya. There is a whole list of programs that would be much better for this type of work. But I think Autocad would be my last choice.

[cuwaert]

I'm on it for weeks now. I succeeded to model the first part of the airplane (a Katana T30) using the lisp's "conic" and "fuseloft" but because of the cockpit, which is a discontinuity I can't modell it in one peace so I tried lofting 2 sections, the midship section and the aft section with 3 guides, and ofcourse it just doesn't do it no matter what I try. So I copied the sections with the guides in another drawing and it doesn't work eighter.

Lofting with one guide , or with no guides works.

I included the drawing here, I hope.

sample.dwg

[JD Mather]

Question is if that's true or do you just need to learn more or do you have the wrong application.

 

There are feature limitations and experience limitations.

At one time AutoCAD did not have a Loft command - so some complex surfacing techniques would need to be used. Can't trim a surface in AutoCAD - break the surface down smaller elements. Can't make a general statement that it can't be done - but becomes either not possible or so difficult as to become not worth the effort.

 

In working around limitations you learn more about the underlying complexity of creating any geometry. Then when the right tool comes along that makes the process more efficient (say Loft) you have a better understanding of how to make the new tool work.

 

So it is an ongoing process - brute force effort to get something to work all the while gaining experience.

 

Then at some point you have an aha moment and what you struggled with before becomes obvious. Or, someone comes along and shows you something that you never even considered. That is the real value of a discussion community like this forum. Ten people might suggest 10 different techniques - the suggestions can be all correct yet different or even incorrect yet we learn something new.

 

You might consult with just one person and they might have a solution to your problem, but you miss out on all of the possible alternative solutions.