uploads/380818/IMG_20130704_0001.pdfHi guys, this is my last drawing with radius. The next 3 are pretty straight forward, house plans. This airplane that I uploaded is the hardest of the lot. I'm really struggling with this, please guys any ideas will be better than none. I'm struggling with the back of the plane and the underneath. Ive manage to do the front and the top part.

I don't think there's enough information on that drawing for you to construct it.  There's nothing at all to tie down anything about the long slightly-sloped underside line, except that possibly its back end is horizontally at the vertical tail center-line, and the curve from the front end of that up toward the propeller doesn't appear to be tangent to it nor to start tangent to the horizontal.  And there are two curves making up the tail for which they don't specify radii.  You would need to guestimate some things, or request a better-defined drawing.

Don't struggle.  :)  And trust me, what I'm about to tell you how to do isn't really cheating... it's just a little, shall we say, innovative.Start a brand new drawing and use the ATTACH command to underlay the PDF into it.  Put it at 0,0 and set the scale at 5000.  You'll know why in a minute. Zoom ExtentsThen select an edge of it and send it to the back (DRAWORDER).  This will allow you to draw lines over it and see them and the PDF at the same time.Now draw a line 5,550 units long.  Why this length?  Because it's the sum of the length of that dimension set across the top.Now the good stuff.  Start the ALIGN command.  Your object is the PDF.  Select it.  When asked for the first source point carefully zoom in and select the far left end of the top dimension line (nr the point of the 60 arrowhead). The destination of this point will be the left end of your 5,550 horizontal line.  Your second source point will be the far right end of the dimension in the PDF. (At the right end of the 467 dimension.)  The second destination point will be the far right end of the 5,550 horizontal line.  You don't have a third source point so just hit <enter> to continue.  For ALIGN scale objects for alignment points say Y (yes) and hit <enter>.And this is where the magic happens.  If you did what I did you drew a RED horizontal line right above the drawing of the plane itself right on the PDF.  (It makes it a little easier to see.)  What happened was that your PDF is now aligned and scaled to that red line.From here you've got something you can trace where you want to or use to help you find circle center points.:)  Have fun!Dave.

... and in the process you'll also learn how to use a VERY handy AutoCAD command:  ALIGN.  Don't be afraid to reALIGN it a second time either if you zoom in and things aren't quite lined up properly.  Sometimes that's worth doing.Oh, and if you have to hand it in, save it as a new filename and Detach the XREF in it.  :)Dave.

heinsite2013-07-10 07:42:59

hello. I just noticed this post and could not help commenting on it. The airplane drawing is incomplete concerning dimensioning. You have to ask yourself what it is that you want for an end product. Is this something that needs to be accurate? Can I draw the tail using the methods I know without reinventing the way plans are drafted? There are many dimensions that are wrongly placed. As well, there are quite a few that are missing within this cartoon. If you are just copying someone else's mistake, then yours will be full of dimensioning errors too. I suggest learning how to read blueprints properly and how to perform basic dimensioning before you go too far with all the 'expert' shortcuts and magical routines, commands and techniques. All the experts out there that glance at this airplane cartoon should know within seconds that it's crap and should not be used for anything.laurencejsmith@shaw.caCADforum contributor

I can confirm what Lawrence says from my own work.  I had to make a few assumptions at the tail and near the prop to complete a drawing.  There is also a dimension missing at the landing gear.  But as an exercise it was an interesting one.  These small, and sometimes missing, details only add to the learning experience because they almost always happen as well in real world projects.  And then you have to deal with them somehow.Dave.
heinsite2013-07-20 00:35:30

When they start making assumptions about dimensions at Boeing I get nervous!  LoL

And then when they bring those same airplanes out to my airport to test them, *I* get nervous!  Dave.