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New to airplanes, have a question about engineering/certification.

SuperFastMatt

Registered User
Colorado
Hello everyone,

This is my first post here on the forum. I'm a longtime airplane enthusiast, but unfortunately I have medical issues that prevent me from ever taking the right seat.

That being said, I always love learning new things, and am here to just have a great time and gain knowledge.

As a practice for my own personal training in SolidWorks, I'm trying to recreate a model of a Cub, and test it through the simulation software.
I'm wondering how to go about finding the loads that were used/spec'd for testing the original Cub, in order to become certified by the FAA.

I'm not sure if that makes sense, as I'm completely new to all of this stuff.
Basically I'm looking for something that says "wings withheld a xxxxLbs load during testing" and other things like that.

Thank you everyone for your help.

Take care,
M
 
Matt,
You can find the gross weights of the various models of Cubs online, then multiply by a safety factor of 2, then multiply by the g load of the category you're designing for. These are 3.8 Normal, and 4.4 Utility. This is from memory, the real work is figuring out how the lift is distributed along the span. Congrats on getting into Solidworks, it's a huge benefit of EAA membership. I saw an SW presentation on the drag of bicycle front wheels, when you get far enough with SW you can probably use it to figure out the distribution. Now if I can just get past "convert entity".
 
The SuperCub is a CAR 3 airplane, meaning it had to meet the requirements of Civil Air Regulation 3 when it was designed. You can find those regulations at rgl.faa.gov clic on the link to civil air regulations and CAR 3. You will also need a copy of the Type Certificate Data Sheet as well, and it is also available there.

Unfortunately, it isn’t as easy as you might think, as you need to calculate the loading in various flight and ground conditions, and from that find the most critical load in each element of the structure. The regulation gives the conditions, the speeds and weights will get you to the actual loading on the airplane. Don’t forget to also factor in the weight of each element as you work your way through the structure.

Good luck with your project. You might also want to get the Northwinds drawings so you have the tube sizes and the wing structure.


Sent from my iPad using Tapatalk
 
I second getting the existing drawings for you to digitize from, I and others have done this. Much nicer than just replicating from pictures. The plane I am building now started by digitizing factory drawings then over some years of continuous evolutionary changes it became time to buy materials and build.
Being a 35+ year AutoCad veteran I have found the "language change" to SW to be difficult. Anyone who has seen my work in ACAD says I could not have drawn what I do to not be possible. Well no one told me that before I figured out how to do it.
So I am one interested to watch your development as you learn your way through this.
I will find it interesting to see if you do the longerons in a spline curve or segmented straight tubes.
 
I got a decent ways along on modelling the assembled fuselage in Solidworks last year for much the same reason as you. If you‘e interested I can send you what I have and hopefully you can share what you learn in simulations as well as the completed model if possible. I believe there‘s a great deal of value in having a model that can be a baseline for further CAD testing of engineering changes.

I modelled the SW model using the Piper and Northland drawings. Drawings can be found on Christian Sturm‘s website, http://www.supercubproject.com/.
 
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