jnaarnold

My Feedback: (4)

Can someone please tell me how to get the dimensions, say of a fuselage or wing if they are not on the drawing....I am extremely new to CAD, so any help would be great. How do I know what size to enlarge to or what size to cut pieces to etc..??

aston70

My Feedback: (1)

What CAD program are you using? With AutoCAD you can just type the 'DI' or 'DIST' command. Then select your first and second point that you want to measure. It will then tell you the distance. If you want to scale your project up or down there are some neat tricks you can do with the SCALE command. I would first pick a reference point. For example the left most point on my wing. Then I would draw a line perpendicular to the wing tip. Or tangent to the outermost point if it's a curved tip. You can snap to these points. Then I would OFFSET this line my desired wingspan. This creates two parallel lines with a distance apart exactly the distance you want your new wingspan to be (Whether it's shorter or longer). Then I use the SCALE command, select everything, and then pick my first point. At this moment you can tell it to scale by reference. I do this by just typing 'R' and enter key. You then have to pick your first point again. Then you select your current object length. In this case it's the current wingspan and a reference line at both wingtips is helpful at this point, or you could use osnap and otrack (Once you get more familiar with them). Then you just drag it out to your new length and snap to the perpendicular of the line you created with your offset command (Or drag it in if you're scaling down). By initially selecting everything when you began the scale command, you scaled everything together and not just the wings. The problem with scaling plans is things won't be what they say they are anymore. For example what used to be a 1/4" stringer is not an acurate dimmension anymore, and I find that I usually have to do some slight redesign when scaling. When you want to plot your parts out ( like ribs, fuse formers, etc. ) so you can cut them out, be sure to plot at 1:1 scaling. Many times the default is scale to fit and your parts don't match up. I may have made this sound more difficult than it really is, but it's actually pretty easy once you do it a few times. If you're not using AutoCAD, the principles will probably be the same but the commands and capability may be different.

Hope that helps.[8D]

aston70

My Feedback: (1)

Another thing I just thought of: When scaling my designs, I usually look up the actual wingspan of an airplane. Then I multiply that by the decimal fraction of the scale I want my design to be. For example, a P-51 mustang has a wingspan of 37' ( I looked this up on google in case it's wrong). Multiply by 12 to get this in inches ( 37' x 12" = 444"). Now if I want a quarter scale design I would multiply 444" * .25 which = 111". So you if did what I said above your parallel lines would be 111" apart. This would give you an exact quarter scale P51 Mustang. Of course many scale designs aren't quite so precise. I've seen planes like this called quarter scale with a wingspan of 102" which is actually 23%, but close enough.

Another way I scale some of my planes is cheating actually. I have drawings of engines and I visually scale the plane to fit the engine. It's a little tricky though and I don't do it often.

BMatthews

Use the help for your CAD to learn to use the dimension or distance tools. Those are what you need regardless of what CAD you have. There's no time like the present to learn. Get chummy with the Help file. It's your friend when the rest of us don't know what you need.

Another possible way if you just want the gross overall dimensions of a part or group of parts is to use the Select tool to select the whole lot and there may be a display somewhere that shows you the dimentions of the area of the selected items. Very crude as I said. Another option is to learn to turn on the ruler bars. Then you can just put the cursor on one point and see what the ruler bar says. Move to the other spot and see what THAT says and then subtract the smaller from the larger number.

aston70

My Feedback: (1)

I agree with BMatthews. Read your help files and search your help files for a specific help topic. I was going to say that too, but I had to stop somewhere. I can see how a lot of people will have an opinion here as everyone probably does it differently, and without knowing which program you're using, we're shooting blindly.

jnaarnold

My Feedback: (4)

If I could give you a file could you just scale it for me?? lol..this is sooo confusing, and I am an automotive technician..hehe

aston70

My Feedback: (1)

Sure, send the file as an attachment to [email protected].