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Outdoor Free Flight Forum => Proven Techniques in building, trimming and flying models => Topic started by: Federico Arenas on February 09, 2013, 11:44:04 PM

Title: Drawing plans
Post by: Federico Arenas on February 09, 2013, 11:44:04 PM
I am finding a best practices for drawing fuselage formers.

I am identify a small and big errors in the plans, I am working with a Cad software and a hand drawing, I suggest to document the best methods to draw a plans and the methods to identify the geomtry of the formers.

In this days the laser cut machines trnasform the work to cut the aeromodels pieces, now for a small mount of money we can produce a pieces with big precision and serial pieces,but to create thos pieces we need draw this in a vector software

Title: Re: Drawing plans
Post by: Warhawk on February 22, 2013, 04:03:35 PM

I suggest that there are quite a number of answers to your best practices - when it comes to plan designs, there are a number of approaches, and it's almost just a personal preference as to how the designer and builder want the pieces and model to look.

I fear that for most, CAD offers diminshing returns when it comes to forming fuselage formers - to be precise for the machine cutting, the part dimensions do have to be exact, and that may take quite some doing for many model plans - a number of them are built from 3-views.

When it comes to building models, maybe it's more practical to oversize formers, and sand to a smooth contour, possibly using contour gauges - which can often be pulled from a decent 3-view.  Then lay on stringers as desired, following the contour?


Title: Re: Drawing plans
Post by: wordguy on February 22, 2013, 05:43:24 PM
Frederico, the variations among plans are so great, that I frankly don't know if there is a "best way."  I also use CAD, and I use a combination of tracing fuselage cross-section profiles, comparing the traced profiles to the width and depth of the fuselage (AND NEVER BUT NEVER EVER ASSUMING THAT THE TOP VIEW OF THE FUSELAGE, OR A FULL-FUSELAGE CROSS SECTION IS SYMMETRICAL), and scaling, stretching, etc.  When there's a gap between printed sections, I usually superimpose sections in front of and in back of the former I need, and then combine bezier curves, arcs, lines, etc. to assemble a shape that I'll once again stretch, scale, and edit in its proper fuselage location.  WRT locating stringers on the formers, I posted my method - not saying it's the BEST method, but only the one that works for me - and even it doesn't work if the fuselage is unusually weird - almost always some fudging is required when I build the proto.

Title: Re: Drawing plans
Post by: slebetman on February 24, 2013, 09:36:25 PM
My personal best method is to still build a prototype. Sometimes I'd draft a preliminary plan and build the prototype out of that but sometimes I'd just build it out of a 3-view.

I still find that I need to work in the real world to fully debug things in 3D. My brain doesn't quite grasp 3D issues on 2D screens. Also, it's often so much easier to work in actual 3D to get things right. After cutting & sanding (and sometimes actually covering and test gliding) I'd deconstruct the plane down to individual parts and scan them into the computer. Then I'd simply trace over the scanned parts in software.

Title: Re: Drawing plans
Post by: Federico Arenas on March 02, 2013, 08:54:38 PM
Hi friend

Im working with the profili software to build the wings, I love ths software because is very useful to create the pieces of the wing, im create many wings whit this software I create the wing in the profili and export to DXF and all pieces I print in a laser cut.

Now Im find this software http://www.devcad.com/eng/devfus_frame.htm, can give me your opinion?


Title: Re: Drawing plans
Post by: packardpursuit on April 01, 2013, 09:12:20 AM
Years ago, with the help of some books from the library on ship building, I taught myself  basic lofting techiques for establishing hull shapes. This was so I could arrive at fuselage formers for my model aircraft projects. Recently retired to an arear where there is still a small ship building industry. Infact there is a large steel fishing boat being built about 1/4 mile away and have really enjoyed watching it come together over the past year.

In any event , what I'm hearing from you guys would seem to indicate that average home CAD is about as accurate ( loose term, I know) as the old drafting methods. As it happens, I just recieved, as a gift, an old set of wooden ship'curves, and this had gotten me thinking about revisiting my old drafting table. I plan on using stringer locations  as the plots for the hull/fuselage diagonal check sections.

Not knocking the new methods, but there  still seems to be some benefit (at least for me), not to mention nostagic reasons, for going back to what works!