CAD Software Onshape help...please...

[JonathanOtt]

I'm wanting to do a simple swept wing in Onshape.

It's actually a SPEC Class FPV Racing wing:

Wingspan: 36" +/- 1/2" Does not include winglets
Airfoil: NACA 0014
Wing sweep: 12" +/- 1/2"
Chord: central- 9", tip- 6" +/- 1/2" (includes elevons!)
Root Chord thickness: 1.25" +/-1/4"
Tip Chord thickness: 0.85" +/-1/4"
I have the airfoil generator in Onshape and can generate the NACA 0014, and can place the root airfoil on a sketch plane and place tip airfoil on a another sketch plane, but I get all goofed up when trying to make the airfoils to spec...getting one to be 9" long, 1.25" tick and the other to be 6" long and .85" thick, then offsetting them in 18" apart and then offsetting the tip 12" aft of the root.

I know there is a simple way to do these tasks, it's just eluding me. The final part of the puzzle is doing the "loft" between the two. I've been able to do that successfully a few times.

Any Onshape experts out there?

 

[robopup]

What specifically is your issue? Usually when I loft wings or fins my process is:

1. Define my airfoil once, with some convenient dimension to scale. For example, in this case I would do a 1" chord. I'm not familiar with the airfoil generator in Onshape, it sounds like some sort of script? Either way, you'll end up with a curve defined by a list of points.
2. Create planes at the root and tip.
3. Project the curve defining the airfoil to the root plane. Scale the curve and add whatever root angle of incidence.
4. Project the curve defining the airfoil to the tip plane. Scale the curve, define a construction line convenient reference points on the root and tip (I like the leading edge) and set your sweep. Like above, also introduce any wing twist here.
5. Loft from the root sketch to the tip sketch. Sometimes it can help to add construction lines from the root to tip leading and trailing edges to use as guide curves.

A few other notes depending on what you're trying to do:

• I use variables for all the typical wing type definitions - wing span, chord length, tip length, sweep, angle of incidence, twist etc. Whatever is convenient, easy to modify and makes engineering sense.
• If your wing additionally has dihedral, the best time to introduce it is in steps 1 and 2.
• Don't use sharp trailing edges. Use some small thickness there - I usually do something like 1/32 in. The CAD geometry and the actual print will behave better.

 

[curtisheisey]

Hi, sorry didn't notice this until now. I think I might be able to help you out.

I have been able to get it to work. I know the loft took a lot of fussing about. I did often use a different (smaller) NACA profile when I did the inner one. I created the loft from big to small. PM me if you are still having issues.

 

[JonathanOtt]

Thanks guys.

What's getting me perplexed is I can make the root and tip airfoils and do the loft, but prior to the loft, I want to move the tip airfoil aft 12" then do the loft.

I've watched a few tutorials, and kinda understand, but have yet to try it...I'll have to watch the tutorials again, and again, and again until I get it.
I figure it can't be that hard, I'm just missing something simple...like using construction lines and making things coincident to each other. Basically I need to watch the tutorial and do the work at the same time to understand it.