What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Solidworks Questions Building it Like Vans Does it

Hi everyone...

I was so impressed when I was building my RV-7 with Vans match hole acuracy, its inspired me to take a look at Cad software

I`m learning Solidworks and having fun. I`m practicing making structures and assemblies and thought why not try to make a wing or structure like Vans would

questions:

do they make the ribs in the sheet metal feature or do they make a solid rib shape extruded and shell it?

for match hole construction/rivets. i`m not that far into the software to consider but some pointers would be great so i`m learning the subjects leading to that

any pointers from Solidwork gurus would be great...

Michael
 
Last edited:
Solidworks is fun, isn't it? You'd have to ask Vans to be sure, but I'd assume they use the sheet metal feature for sheet metal parts with the material set appropriately to preserve bend radius and match the CNC tooling. Other parts, such as the cowling, would be a shell or, like weldments or thick parts such as spar strips, drawn in simple form.

I haven't played around with hole-matching but I suspect you could use assembled parts to match holes. For instance, build a rib with holes, assemble it at stations to a spar and wing skin, then locate holes in those parts to match. This thread has some suggestions.
 
I work with SolidWorks quite a bit. I would bet they use the sheet metal tool for most of the airframe and the cowl/tips/ most fiberglass stuff is probably done with surfacing commands. Surfacing commands is an area I could get better with but they are significantly harder to use.
 
Keep in mind that the airfoil shape isn't comprised of flat segments, it's a continuous curve. So you'll have to reconcile making flat tabs sit against a curved skin at some point.

Think in terms of how the parts are actually made... The shape is cut out of a flat piece of aluminum, and then it is formed over a die to make the rib (if you look at the leading edge, the tabs aren't flat, they are curved to match the wing skin.

Solidworks has a Deform tool that will let you push one piece into another... Perhaps this will give you some ideas?
 
Keep in mind that the airfoil shape isn't comprised of flat segments, it's a continuous curve.

I've plotted several airfoils. Use straight lines to do them. This is done using AutoCAD in a 2D drawing.
airfoil-plot1.jpg


Airfoil-plot3.jpg


Best regards,
Mike Bauer
 
Last edited:
I think the method depends on which release of Solidworks you are using. Older versions in sheet metal didn't allow unbending of a curved flange, only a straight one, so do some experiments to see if you can unbend a curved flange.

To comment on Mike's last post, when I do an airfoil in Solidworks (mine are castings for marine propulsion) I use a spline through coordinate points. These solid models work great with my patternmaker.
 
I think the method depends on which release of Solidworks you are using. Older versions in sheet metal didn't allow unbending of a curved flange, only a straight one, so do some experiments to see if you can unbend a curved flange.

To comment on Mike's last post, when I do an airfoil in Solidworks (mine are castings for marine propulsion) I use a spline through coordinate points. These solid models work great with my patternmaker.

Have Inventor 2019, just learning how to do the Feature Base Modeling in it. Mastering Sheet Metal Design with Inventor is my go to book for instruction.

Most of my CAD work has been Civil Engineering. Hobby is designing model rockets/airplanes.

Up till now been doing the designing in 2D.

After doing the math for the particular airfoil, baselines are drawn, then I just use offsets to make my "coordinates".

Guessing you use more software to create your coordinates, or does Solidworks plot them for you? (patternmaker?)

I have drawn the airfoils with the spline command, making changes if needed became an issue. (ACAD R14)

Best regards,
Mike Bauer
 
Last edited:
I've plotted several airfoils. Use straight lines to do them.
Yes, as do I. But when you actually build it, do you crease the skin at the end of each straight line segment, or do you "fit the curve" with the skin and have a continuous curve? You model the continuous curve in Solidworks.
 
I've done a couple aircraft in Solidworks. It's really hard to design an aircraft piece by piece without having an idea of the finished layout.

I like to draw the whole aircraft as a solid. Get the look, layout, and positioning down. This gives me the mold lines for all the bulkheads, ribs, and other parts. Then I decide the layout of the ribs and bulkheads and start slicing the solid model to get the mold lines for each sheet metal part. Doing it this way allows me to change the shape of the solid model and the parts made off of it get automatically changed.

Brandon
 
Guessing you use more software to create your coordinates, or does Solidworks plot them for you? (patternmaker?)

Best regards,
Mike Bauer

I generally start with a set of coordinates from an airfoil book. Then use Excel to scale these coordinates to the chord and thickness I need. Then plot these coordinates in Solidworks as points in a 2D sketch. Join the points with a spline then extrude to the length required. You can do this with different sections, say root and tip, as long as the number of spline points (coordinate points) are the same for each section. In this case you would use a sweep or a loft. Sometimes guide curves between sections are required to keep the solid from twisting between sections.

Once I have a solid model, I send this to our patternmaker who has a 3/5 axis gantry CNC milling machine. They scale the solid model to allow for cooling shrinkage depending on the actual casting material. The pattern is made of wood. The foundry then uses this pattern to make a mold to make the casting.

This is one of the things I love most about using 3D CAD - the CAD/CAM connection. Most gratifying to see your solid model turned into an actual part.
 
Van's U

I'd pitch in $100 to have Van's engineers make a series of step-by-step youtube videos showing how to do a structural and aeroelastic analysis of, say, a simple empennage model. Let's a hundred of us pledge to make it worth someone's while?

In this new normal they could then totally expand into distance learning and grant degrees. Buy-your-own sheet metal to graduate. :D
 
Yes, as do I. But when you actually build it, do you crease the skin at the end of each straight line segment, or do you "fit the curve" with the skin and have a continuous curve? You model the continuous curve in Solidworks.

I see what you're saying. Never considered what the difference would be for a full size aircraft.

My designs are small models made using cardstock paper, 7ft Long SR71 Blackbird is my biggest airplane so far. The angle on the connections is so small that just cutting the rib outline and skinning with cardstock paper makes it look like a continuous curve. Actually when cutting the ribs, they already look like a continuous curve.


@Terry- Thank you for the explanation. Sure sounds like you have a great career!

@Brandon-Thank you for mentioning how you design. Makes perfect sense.

Best regards,
 
Last edited:
I've done a couple aircraft in Solidworks. It's really hard to design an aircraft piece by piece without having an idea of the finished layout.

I like to draw the whole aircraft as a solid. Get the look, layout, and positioning down. This gives me the mold lines for all the bulkheads, ribs, and other parts. Then I decide the layout of the ribs and bulkheads and start slicing the solid model to get the mold lines for each sheet metal part. Doing it this way allows me to change the shape of the solid model and the parts made off of it get automatically changed.

Brandon

Very interesting subject to me, so I couldn't help throwing in my 2 cents. Brandon's approach is very close to mine. I've been using SW since about 2007 in our business designing RV interior components (mostly sheet metal parts). In my spare time :rolleyes: I've dabbled with a few aircraft designs over the years. I hope to eventually get one flying.

Anyway, I find that design of any kind is a very iterative process with many changes over time. It's easy to get bogged down with the mechanics of using the software even once you are very proficient.

For me it helps to work with a single part file to work out the complex relationships between multiple related parts. These parts are actually just individual "solids" in the same part file. I think of this file as a very rough concept. Once I like the layout, I basically go back and redesign everything from the ground up in proper part and assembly files. It works great for working through issues in subassemblies.

One other secret weapon when doing machanical design with SW is to make use of the McMaster Carr website (and many others) for solid models of many hardare parts and piece you can download directly. Fun stuff.
 
One other secret weapon when doing machanical design with SW is to make use of the McMaster Carr website (and many others) for solid models of many hardare parts and piece you can download directly. Fun stuff.
Hey now, don't give away *all* the secrets or soon those of us who do this for a living will be out of a job! :p

McMaster is my standard reference for fasteners as well. I've stopped creating part numbers for fasteners, I just use McMaster's numbers and specify them as the default source. If customers want to get fasteners elsewhere, finding the detailed spec for the fastener is easier by going to McMaster with their part number.
 
Thanks for all the great responses

Ive hit a snag and wondering if anyone of you know of a work around

The issue is the spline tool in the Solidworks sketch

I`m posting here after reading about 10 posts by different posters on Solidworks and CADforums has on this topic


The spline tool seems so useful I’m surprised that there are issues with it being the software is 20 plus years old. I’m new so maybe I just don’t know all the alternatives to add curves to airframe parts... ect
Ive been making practice wing shapes/airframe parts, by making a center line and then drawing lines up and down off that. Then take the spline line tool and connect the dots. Ive been using this method for wing shapes that don't have airfoil coordinates or just for making curves and air frame shapes


But when I put that sketch onto a drawing in Solidworks or export that drawing to a PDF.....the nice curve of the spline line is gone, replaced by a number of short lines(polylines) that approximate the curve....so from far away it looks ok but up close its very blocky

On the solidoworks forums and Cad forums people seem to be stumped by this issue...that the spline tool creates great curves in sketch mode but anytime those curves are exported to do a 3D print or PDF..ect...the curves disappear and blocky lines are put in it place. Some have talked about using arcs to make curved shapes as a work around. Any of you have experience with arcs or other tools to do wing type shapes? I`m new this cad world, can the arc tool be extended like a spline?

This is after adjusting image quality settings and options in how the PDF is saved...etc..looks like almost every stone has been turned looking for an answer to this...

I dont know how to host pictures on this site to show you ...or I would post some examples...

Ive made the exact same sketch in fusion360 and had no issues exporting or printing, but I want to stay with solidworks as its the EAA choice

Maybe youve run into this yourself and have a solution

Michael

below is a post off the solidworks forum of someone posting on the same issue





I am trying to export a drawing to Illustrator so that i still have splines and circles. At some point this must have worked for me, as i have old exported DXF files which have splines in them. But with my current Drawing i cant get it to work, Solid Works will export all the Splines and Curves as edgy polylines! I already tried all the options and different DXF standards, but nothing helps...

Thanks for your advise!

Philip



This is a link to another person same issue

https://forum.solidworks.com/thread/223872
 
Last edited:
How to enter airfoil cordinates into solidworks

Another question for you guys, i`ve watched all sorts of videos on entering ready made airfoils into solid works. But what if you want to enter your own?

If I have measurements from an airfoil , solidworks has a manual entry system to put them in under insert/curves/curves through xyz points

the thing is, I cant find anywhere an explanation on how the numbers should go in. If anyone has done their own airfoil matrix for solidworks from scratch, id love to hear about it.

I have measurements I want to try but every time i put them in I`m creating a modern art image and not an airfoil...lol

Michael
 
Last edited:
If I have measurements from an airfoil , solidworks has a manual entry system to put them in under insert/curves/curves through xyz points

the thing is, I cant find anywhere an explanation on how the numbers should go in. If anyone has done their own airfoil matrix for solidworks from scratch, id love to hear about it.
I haven't used the xyz points method, but I imagine all you need to do is enter your coordinates for your airfoil in two of the axes, and zeroes in the third axis.

The other way would be to just sketch them and dimension them. Draw a line from the origin straight along one axis to make your chord line, then draw vertical lines from the chord line to each point on the profile. Your airfoil coordinates are then the distance of the vertical lines from the origin, and the height of each vertical line. It's more labour-intensive to draw and dimension this way, but it's equally valid.
 
But when I put that sketch onto a drawing in Solidworks or export that drawing to a PDF.....the nice curve of the spline line is gone, replaced by a number of short lines(polylines) that approximate the curve....so from far away it looks ok but up close its very blocky

Can confirm i've seen this for years as well, and have never found a solution.
 
Can confirm i've seen this for years as well, and have never found a solution.

Does SW have any Nurbs controls to adjust how they appear?

Non-uniform rational basis spline

Non-uniform rational basis spline (NURBS) is a mathematical model commonly used in computer graphics for generating and representing curves and surfaces. It offers great flexibility and precision for handling both analytic (surfaces defined by common mathematical formulae) and modeled shapes.

Could it possibly be a setting in Illustrator when importing splines/Nurbs?

Whoops-reread posts. PDF is based on bitmap/pixels, not vector, Illustrator is based on vector. When a vector drawing is converted to bitmap, you loose the vector lines, they are converted to single dots to make the line/drawing appear correct. Vector uses geometric shapes to show a line or curve.

Mike
 
Last edited:
Can confirm i've seen this for years as well, and have never found a solution.

What I?m doing is using fusion360 for curved practice parts. The spline tool seems to work seemlesssly there

And staying with solidworks for parts with straight edges

I was kinda hoping to not have to learn 2 systems but I guess it is what it is

I?m a little disappointed with solidworks about this... looking at the forums people have been talking about this since 2011... I don?t know the behind the scenes math of why it won?t work but you would think they would have worked out something by now.

Michael
 
Printing accurate cutting templates

share some info I’ve learned doing some research

Many printers are not accurate(when I say accurate I mean long or short up to an 1/8 of an inch over a yard). and anything you print should be double checked. You might have to scale it up or down a little . But even then you should check that it got scaled evenly on both the x and y axis

Some printers are accurate on the x axis but not the y

I don’t own shares in the company but after trying a few different printing shops and a few printers in each shop

The Hewlett-Packard page wide printer seems to be very accurate ... over a yard/meter test print I could find no diviation.. it was spot on... but I still do a quick test measure up and down the page to check it.

If anyone is familiar with other good printers or what to ask for as far as a calibrated cad printers... please educate us. Maybe these print shops need to calibrate their printers?

With that said I would double check your testing ruler against another ruler or caliper to make sure that’s accurate..


With a good printer you can make templates to stick on your aluminum. that once cut out should match your project demesions
 
Last edited:
If I were going to all the trouble of drawing up the part in CADCIM, I'd use CNC technology to 'print' the part. I haven't used Solidworks for sheet metal, but other parts have been done for me on a CNC mill, for example. I'm sure you could find a shop that will cut sheet metal to your drawings. If you are templating the bend lines, the usual practice is to use forming blocks with tooling holes to fix the blank on the block. Too bad SW does not have a feature to autogenerate forming blocks based on the drawing and material.
 
Heads-up: Solidworks gives a free license to EAA members. It's a killer deal. Several thousand bucks worth of high-end software.

https://www.eaa.org/solidworks

Yes, and uh there is a reason for that....I have been using the EAA version for several years. They got me where they want me :rolleyes:. If I ever needed a commercial version of CAD it would be Solid works due to the amount of time I have spent learning it. Even if another vendor was super cheap.... I hope they never discontinue the education version with EAA or I will be out a luck.
 
Whoops-reread posts. PDF is based on bitmap/pixels, not vector...

Um... No. PDF was designed specifically to contain vectors. But it may also contain bitmaps. What Solidworks exports in PDF's is not bitmaps, it's vectors, but curves are made up of short (vector) line segments.

way_up_north said:
What I?m doing is using fusion360 for curved practice parts. The spline tool seems to work seemlesssly there...And staying with solidworks for parts with straight edges

If you're designing parts for machining/forming/etc. later, and people will be making the parts from a Solidworks native tile, or a STEP or IGES output of that Solidworks file, there's no reason to use Fusion.

If you're planning on making a PDF and printing it out and having a shop make a part from that PDF, then you're already accepting a quality level that isn't going to be affected by having the curves show as short line segments...
 
Back
Top