TaylorRAmes
New member
Hello all! I just finished up "version 1" of my custom FT Commuter build, so I decided I'd share some of my journey with all of you. This project started just over a year ago when I bought my FT Commuter kit...or at least when I tried to buy the kit before I got an email saying it had been discontinued. I liked Cessna aircraft and desperately needed a trainer after crashing my first two Mini Mustangs, so I wasted no time heading to the dollar store and getting supplies to build my own Commuter. Three days, a cut thumb (unrelated), and lot of scrap foam later, I finally had the trainer of my dreams. It flew beautifully, but one thought kept going through my mind.
This is going to be a pain in the butt to rebuild if I crash it.
So, with a student license of Fusion 360 and 6 months left of school (Mech. Eng. Student, Graduated in Dec 2023), I made it my goal to 3D model the entire plane so I'd never have to hand cut the nose again.
The first version of the nose took heavy inspiration from the foam kit, keeping the same lines, making use of a 3d printed motor mount, and completely disregarding the battery. Whoops. After correcting my mistake and adding some skewer holes to help align it to the plane, I hot glued it in place and took it out for its first maiden. It flew wonderfully, but what was before a modest task of transferring the design now became a red hot fury of new ideas, concepts, and features I wanted to add. I mean, I'm already going to be modelling the whole thing, I might as well do some designing of my own.
I redesigned the nose again to remove the powerpod, remove the hard lines from the foam model, and add nose wheel steering - automatic 10/10 upgrade. Then I began working on the wing. I had a video explaining the evolution of the wing, but since I can't post that here, I'll do a quick explanation of the four versions of the wing.
Each wing was loosely based on the dual airfoil design most small FT planes have - a normal airfoil (Clark Y), and a high drag, high lift airfoil at the wing tips (Some STOL NACA airfoil, don't remember which one). The airfoil was constant until midspan of the wing where it gradually transitioned to a higher lift airfoil at the tip. I also added flaps that spanned half the wing, increased the wing span by 2in, and had integrated servo mounts.
Wing V1: 1 central skewer in each wing, 2 skewers holding the two halves together and setting the dihedral. Mounts for the skewers were molded into the 3 spars which ran the entire length of the wing. It was 5 pieces, held together by superglue and the skewers, and was hot glued to the foam fuselage. This design was extremely strong, but lacked rigidity at the trailing edge where the control surfaces mount and was very heavy at >200g for the completed wing.
Wing V2: Added 1mm x 1mm crisscross reinforcing lines to the upper and lower skins to help increase rigidity at the TE. Still heavy, still weak.
Wing V3: Ditch the crisscross reinforcements, add ribs at each of the wing joints (4 total) to increase rigidity. This is the first version of the wing that flew. During a test flight, the plane was extremely hard to fly and barely made it safely onto the ground. I determined the new wing tip profile and heavy weight were both to blame - These areas were both addressed in the V4.
Wing V4: Complete redesign. I got an engineering job at an aircraft company, so I decided I wanted to use a more traditional design and use this plane as an opportunity to learn and practice new analysis techniques. I switched to a 3 section wing with two outer ribs and 1 large central rib, switched from integrated spars split at each wing section to a single, continuous spar running through each wing half, and now I'm using the continuous spar, central rib, and wing skins to provide the strength instead of the skewers. I also modified the servo hinges to use actual hinges instead of TPU and made the parts printable without support. Finally, I added the strut mount and calculated the stress reduction and new critical location the strut would provide.
This new wing design was weaker than before, but using actual aircraft wing analysis techniques, I designed it to take a 25G load when printed using prefoamed LW-PLA. I ended up printing the plane using Esun foaming LW-PLA which is much lighter and weaker, so the version I will actually be flying is significantly weaker. I am taking this opportunity to learn some fiberglassing techniques, but I don't expect to need that extra strength considering this is my trainer. I know how to fly, but you get the idea. It won't be doing any acrobatics. Not yet... : )
Next up was the fuselage. I made some mistakes while modeling this (Bad constraints, bad projections, oversights, etc), so I will be completely redesigning this in the future. It's pretty similar to the foam version, just with some added reinforcing frames, screw mounting holes for the nose, wing, and tail, and a strut mount. I did do the math to see what kind of loads the fuselage will see, but I am not going to waste time trying to reinforce this version. The fuselage will split in two during a hard landing and will be ripped in three during a 25G maneuver. Moving on, lol.
The tail is relatively simple - it consists of a tail boom with some integrated reinforcements, locating pins, and screw mounts for the fuselage, a stabilizer fitting where the H-stab and V-stab mount and control wires run through, and the control surfaces. Although its simple, this is the part of the plane I am mose pleased with. The H-stab is locked in place by the V-stab, the V-stab is held in with 2 screws, and the whole assembly glues perfectly into the tail boom. Simple, elegant, and very strong. It also looks gorgeous!
You can tell I got tired of writing near the end, lol. It's definitely not perfect, but when is a "Verison 1" ever perfect? You can probably see why I keep putting that in quotes. Between all the redesigns and individual parts, there have been over 350 total revisions made to this assembly, and I have spent 4 rolls of filament experimenting with the design. If anything interesting happens during the maiden of the fully 3d printed design, if I reach a milestone in the redesign, or if I remember an interesting part of the development process that I missed, I will post an update here.
Edit: Added 6 more screenshots of the V1 3D model.
Edit #2: Added 2 pictures of the V2 and V3 wing designs
This is going to be a pain in the butt to rebuild if I crash it.
So, with a student license of Fusion 360 and 6 months left of school (Mech. Eng. Student, Graduated in Dec 2023), I made it my goal to 3D model the entire plane so I'd never have to hand cut the nose again.
The first version of the nose took heavy inspiration from the foam kit, keeping the same lines, making use of a 3d printed motor mount, and completely disregarding the battery. Whoops. After correcting my mistake and adding some skewer holes to help align it to the plane, I hot glued it in place and took it out for its first maiden. It flew wonderfully, but what was before a modest task of transferring the design now became a red hot fury of new ideas, concepts, and features I wanted to add. I mean, I'm already going to be modelling the whole thing, I might as well do some designing of my own.
I redesigned the nose again to remove the powerpod, remove the hard lines from the foam model, and add nose wheel steering - automatic 10/10 upgrade. Then I began working on the wing. I had a video explaining the evolution of the wing, but since I can't post that here, I'll do a quick explanation of the four versions of the wing.
Each wing was loosely based on the dual airfoil design most small FT planes have - a normal airfoil (Clark Y), and a high drag, high lift airfoil at the wing tips (Some STOL NACA airfoil, don't remember which one). The airfoil was constant until midspan of the wing where it gradually transitioned to a higher lift airfoil at the tip. I also added flaps that spanned half the wing, increased the wing span by 2in, and had integrated servo mounts.
Wing V1: 1 central skewer in each wing, 2 skewers holding the two halves together and setting the dihedral. Mounts for the skewers were molded into the 3 spars which ran the entire length of the wing. It was 5 pieces, held together by superglue and the skewers, and was hot glued to the foam fuselage. This design was extremely strong, but lacked rigidity at the trailing edge where the control surfaces mount and was very heavy at >200g for the completed wing.
Wing V2: Added 1mm x 1mm crisscross reinforcing lines to the upper and lower skins to help increase rigidity at the TE. Still heavy, still weak.
Wing V3: Ditch the crisscross reinforcements, add ribs at each of the wing joints (4 total) to increase rigidity. This is the first version of the wing that flew. During a test flight, the plane was extremely hard to fly and barely made it safely onto the ground. I determined the new wing tip profile and heavy weight were both to blame - These areas were both addressed in the V4.
Wing V4: Complete redesign. I got an engineering job at an aircraft company, so I decided I wanted to use a more traditional design and use this plane as an opportunity to learn and practice new analysis techniques. I switched to a 3 section wing with two outer ribs and 1 large central rib, switched from integrated spars split at each wing section to a single, continuous spar running through each wing half, and now I'm using the continuous spar, central rib, and wing skins to provide the strength instead of the skewers. I also modified the servo hinges to use actual hinges instead of TPU and made the parts printable without support. Finally, I added the strut mount and calculated the stress reduction and new critical location the strut would provide.
This new wing design was weaker than before, but using actual aircraft wing analysis techniques, I designed it to take a 25G load when printed using prefoamed LW-PLA. I ended up printing the plane using Esun foaming LW-PLA which is much lighter and weaker, so the version I will actually be flying is significantly weaker. I am taking this opportunity to learn some fiberglassing techniques, but I don't expect to need that extra strength considering this is my trainer. I know how to fly, but you get the idea. It won't be doing any acrobatics. Not yet... : )
Next up was the fuselage. I made some mistakes while modeling this (Bad constraints, bad projections, oversights, etc), so I will be completely redesigning this in the future. It's pretty similar to the foam version, just with some added reinforcing frames, screw mounting holes for the nose, wing, and tail, and a strut mount. I did do the math to see what kind of loads the fuselage will see, but I am not going to waste time trying to reinforce this version. The fuselage will split in two during a hard landing and will be ripped in three during a 25G maneuver. Moving on, lol.
The tail is relatively simple - it consists of a tail boom with some integrated reinforcements, locating pins, and screw mounts for the fuselage, a stabilizer fitting where the H-stab and V-stab mount and control wires run through, and the control surfaces. Although its simple, this is the part of the plane I am mose pleased with. The H-stab is locked in place by the V-stab, the V-stab is held in with 2 screws, and the whole assembly glues perfectly into the tail boom. Simple, elegant, and very strong. It also looks gorgeous!
You can tell I got tired of writing near the end, lol. It's definitely not perfect, but when is a "Verison 1" ever perfect? You can probably see why I keep putting that in quotes. Between all the redesigns and individual parts, there have been over 350 total revisions made to this assembly, and I have spent 4 rolls of filament experimenting with the design. If anything interesting happens during the maiden of the fully 3d printed design, if I reach a milestone in the redesign, or if I remember an interesting part of the development process that I missed, I will post an update here.
Edit: Added 6 more screenshots of the V1 3D model.
Edit #2: Added 2 pictures of the V2 and V3 wing designs
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Boom Internal.png -
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Nose.png -
Stab Fitting and Lock.png -
Tail.png -
Wing V2.png -
Wing V3.png
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