How do you begin designing a new aircraft from scratch?

[landedit]

Hello all, this summer I have big plans to convert a couple of planes to a flitetest style of build. I'd like to begin with an Airbus A400M. However, I'm not sure how to go about getting things like the wings built, both close to scale in look but also in function. I've tried using images in corel draw where I make my other laser cutter files for FT planes but I usually get stuck trying to figure out wing and body folds and how they would come together. Would something like Fusion 360 work better? What do you all use? Maybe I am approaching this the wrong way entirely

 

[TEAJR66]

Pick your CAD flavor and dig in. One bite at a time, you will get it digested.

I have used Fusion 360 and Sketchup. In the end, I like Sketchup for folded foam and Fusion for 3D printed stuff.

Figure out how close to scale you want to be. This might determine if you use traditional FT 3 or 4 break wings, A, B, C folds, and power pods, or go with the scale appearance of the molded and bent foam as seen in the master build series.

Do a search for aircraft design in the articles and forums. Lots of good info out there.

Keep us posted on your progress.

 

[landedit]

Pick your CAD flavor and dig in. One bite at a time, you will get it digested.

I have used Fusion 360 and Sketchup. In the end, I like Sketchup for folded foam and Fusion for 3D printed stuff.

Figure out how close to scale you want to be. This might determine if you use traditional FT 3 or 4 break wings, A, B, C folds, and power pods, or go with the scale appearance of the molded and bent foam as seen in the master build series.

Do a search for aircraft design in the articles and forums. Lots of good info out there.

Keep us posted on your progress.

Thanks for the reply. I use sketchup for a lot of my woodworking stuff currently but didn't really think about using it for planes. I'll give it a shot. I had been considering making some videos of the process to keep track of the progress and to hopefully help others if they decide to use my methods so maybe I'll have to do that.

Thanks again!

 

[kingstat]

Thanks for the reply. I use sketchup for a lot of my woodworking stuff currently but didn't really think about using it for planes. I'll give it a shot. I had been considering making some videos of the process to keep track of the progress and to hopefully help others if they decide to use my methods so maybe I'll have to do that.

Thanks again!

I just saw these articles and I think this is exactly what you are wanting to do/learn.

https://www.flitetest.com/articles/sketchup-for-rc-aircraft-design-tutorial-1

 

[landedit]

I just saw these articles and I think this is exactly what you are wanting to do/learn.

https://www.flitetest.com/articles/sketchup-for-rc-aircraft-design-tutorial-1

You're awesome! This looks like exactly what I need. Thanks!!

 

[TEAJR66]

Here is another that might help. I really need to do the second part to this series.

https://www.flitetest.com/articles/balsa-plans-to-foam-conversion-in-sketchup

 

[datamichael]

I am proficient with Fusion 360, but the lack of "unfold" option makes using it for foam board models quite tedious. I am interested in Sketchup as there is an "unfold" extension, but it looks like it's $300 per year for a subscription. Is that correct, or am I missing something?

Pick your CAD flavor and dig in. One bite at a time, you will get it digested.

I have used Fusion 360 and Sketchup. In the end, I like Sketchup for folded foam and Fusion for 3D printed stuff.

Figure out how close to scale you want to be. This might determine if you use traditional FT 3 or 4 break wings, A, B, C folds, and power pods, or go with the scale appearance of the molded and bent foam as seen in the master build series.

Do a search for aircraft design in the articles and forums. Lots of good info out there.

Keep us posted on your progress.

 

[Land Shark]

SketchUp is my best friend. Easy to use and 100% free. And I couldn't live without graph paper.

 

[datamichael]

I do see there is a free version of SketchUp. However, it's browser-based and the "unfold extension" is only available for the Pro ($300) version. Am I missing something?

SketchUp is my best friend. Easy to use and 100% free. And I couldn't live without graph paper.

 

[Vimana89]

There's a wealth of information from people about rendering on here using those types of programs. I never bothered to get good with those, but I always used to sketch and draw and make paper planes as a kid, so I find I'm better suited(at least at this point in my journey) to using pencils and graph paper to draw up templates for my own designs then just use a ruler and straight edge. I don't know why you would need to render the folds in your plane coming together. If using FT style cuts and folds your gouging out a straight 4mm(or however thick your board) rectangular strip between whatever two walls are being folded and leaving the paper. If using those programs you really only need to render your flat template pieces to be printed out and assembled, and not worry about rendering the finished product or the process of stuff coming together.

 

[TEAJR66]

I am proficient with Fusion 360, but the lack of "unfold" option makes using it for foam board models quite tedious. I am interested in Sketchup as there is an "unfold" extension, but it looks like it's $300 per year for a subscription. Is that correct, or am I missing something?

Find Sketchup Make from 2017. Still works great and all the plugins are still available.

 

[TEAJR66]

I do see there is a free version of SketchUp. However, it's browser-based and the "unfold extension" is only available for the Pro ($300) version. Am I missing something?

You want the 2017 version of Sketchup Make.

 

[TEAJR66]

There's a wealth of information from people about rendering on here using those types of programs. I never bothered to get good with those, but I always used to sketch and draw and make paper planes as a kid, so I find I'm better suited(at least at this point in my journey) to using pencils and graph paper to draw up templates for my own designs then just use a ruler and straight edge. I don't know why you would need to render the folds in your plane coming together. If using FT style cuts and folds your gouging out a straight 4mm(or however thick your board) rectangular strip between whatever two walls are being folded and leaving the paper. If using those programs you really only need to render your flat template pieces to be printed out and assembled, and not worry about rendering the finished product or the process of stuff coming together.

Yep. You work primarily with the outer skin. The outer skin is what gets flattened to make the plans. I add the A and B fold cut lines after I have the plans laid out.

Building the model in 3D let’s you check the appearance. Flattening lets the computer do the measuring.

 

[datamichael]

You want the 2017 version of Sketchup Make.

Thanks for the info! I was able to find/download Sketchup Make 2017. Unfortunately, it too only give you a 30 day trial period for free. The only totally free version available now is the web-based version.
I'll play with it for a while and if I like it, I'll pay for it.

 

[Hondo76251]

Just my $0.02...

I've learned far more and have become a better designer/builder by spending more time at the workbench and less time at the drawing board...

For your first few true ground up scratch builds I'd work on perfecting your skills and learning techniques that you like to use (folded foam vs hotwire cut airfoil wing... etc.) so when you want to work up to a more detailed "scale" build you can design a build plan that works for you.

I'll generally start with the power plant i'm using. (motors from crashed drone, spare parts from other projects, deals found online etc..)

From there I can determine the rough size/weight I can manage at that power level.

Lay out a sheet of foam... ruler and pencil, then blade and glue, a little soldering, then fly, crash, repair, repeat...

 

[Ryan O.]

With curves, like would likely be used on jetliners I use paper to get the outline, then I use measurements (foam thickness and needed paper overlap). This isn't the most efficient way, but I can't afford Coreldraw or a laser cutter. If doing it this way be sure to use plans and duplicates.

 

[landedit]

Thanks for the info! I was able to find/download Sketchup Make 2017. Unfortunately, it too only give you a 30 day trial period for free. The only totally free version available now is the web-based version.
I'll play with it for a while and if I like it, I'll pay for it.

I still have the free version, you only lose pro features after 30 days. But if you can't find the download for the free version I am fairly confident I have a copy of it at home, I could email you the file.

 

[datamichael]

I still have the free version, you only lose pro features after 30 days. But if you can't find the download for the free version I am fairly confident I have a copy of it at home, I could email you the file.

Thanks for the offer!
I purchased a full copy.

 

[Corbarrad]

I use fusion 360 for all my 3d prints.
I really want to try and design a plane from scratch and I have a good idea on what my parts are and how they will fold up to get the final shape. My thought is that for the outer "skin" I will try and model the exterior as closely as possible while keeping it kinda low poly and then use the "sheet metal" function to try and lay it out flat.

I gave myself til Flitefest to find out if this works.

 

[slembcke]

So a lot of people have talked about the form, but not the function. I've been reading through my brother-in-law's intro to aircraft engineering textbook, which is fascinating, but more detail than you really need to make a flyable RC plane. This MIT open course work guide is 8 pages of gold though: Basic Aircraft Design Rules Using that I've had a couple planes that flew well on the first try without guessing how big/long the tail should be.

It does require you to have an estimate of your coefficient of lift to determine a dihedral angle though. I just start at 5 degrees and lower for the second revision it if it's not acrobatic enough.

Other than that, some other random tips to keep in mind:
* Long skinny wings are efficient and glide well. Short stubby wings are strong.
* Tapered wings are efficient. Elliptical tapering is ideal, simple tapering to 45% chord is pretty close.
* Swept wings act like dihedral to add roll stability.
* Try to avoid adding too much stability in any particular axis or your plane won't fly well, or will cause instability on other axes. (ex: dutch roll)