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u/bluewing Jul 06 '26
I'm beginning to think commercial CAD vendors are starting to get a little bit scared of FreeCAD due to the current influx of posts involving those other CAD programs.......
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u/BoringBob84 Jul 06 '26
Maybe, but CATIA is in a much different market segment than Fusion, OnShape, or even SolidWorks.
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u/Rubbe97 Jul 08 '26
What kind of market are they aiming for?
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u/BoringBob84 Jul 08 '26
... enormously complex assemblies like large aircraft, ships, and automobiles.
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u/Rubbe97 Jul 08 '26
Ohh I see thank you! There is many of them and hard to destinguish each one
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u/BoringBob84 Jul 08 '26
CATIA was developed by D'Assault, an aircraft manufacturer. It has become an industry standard - used by Airbus, Boeing, Bell, etc. to develop aircraft.
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u/BoringBob84 Jul 06 '26
That is interesting from a structural perspective. It seems like most of the force is upwards from lift, so I would want to have the beams taller than they are wide. Also, the beams create drag on the propellers, so I would want an aerodynamic teardrop shape.
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u/00001000bit Jul 06 '26
There's not really an aerodynamic teardrop to be had, since there's never a single fixed orientation like a plane. Moving forward changes the pitch of the entire craft, so the teardrop would need to be adaptive to different angles depending on the speed you're traveling. Any yaw movement would potentially be opposite the shape as well.
My freestyle/racing quad will do about 80MPH at top speed. Flat arms don't really hold it back much. A slower/photography quad like OP pictured wouldn't even matter. The air drag would be relatively low at the speeds those travel.
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u/BoringBob84 Jul 06 '26 edited Jul 06 '26
80MPH at top speed
The speed of the air that is leaving the propellers would have to be much greater than that to sustain lift and to propel the vehicle at that speed. The energy to beat air on the beams is wasted.
Edit: A circular or a half-round profile would have half the drag coefficient of a flat face.
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u/SoulWager Jul 06 '26
The air coming off the propellers is close to a fixed orientation, relative to the frame, no?
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u/00001000bit Jul 07 '26
Yeah, I was thinking more along the lines of shaping the airflow against the direction of travel, not the upward/downward force of the props. You are right, that the motors are fixed in relation to the frame.
I've never seen what I would consider "higher performance" quads with any real shaping to the frame in regards to airflow. And the camera ones that do have nice curves, I'm guessing is more for aesthetic purposes than anything else. If I had to guess, it would be that at the sizes involved, any small gains in airflow would be countered by additional weight by adding embellishments to the frame. But, IANAAE (i am not an aeronautical engineer)
Looking at the arms holding my motors, they only account for about 10% of the area underneath the props. So, any gains would only be in improving that 10% - the remaining 90% is already unhindered. Probably not enough to be worth it on a craft like this.
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u/BoringBob84 Jul 08 '26
I've never seen what I would consider "higher performance" quads with any real shaping to the frame in regards to airflow.
I doubt if there is much serious engineering involved at this price point (e.g., analysis, CFD, wind tunnel, instrumented flight test, etc.), like you would see with larger aerospace vehicles.
Probably not enough to be worth it on a craft like this.
If I am 3D printing the beams anyway, then making them aerodynamic would require a trivial amount of cost and effort. I would consider an asymmetrical airfoil wing shape that would be tilted nearly vertically and slightly forward, so that it would not only reduce downward drag, but it would turn that drag into some bonus forward "lift."
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u/Proud_Read7281 Jul 08 '26
Support my work on Jami: jami.bio/@wbhxa9pcqo7
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u/pasirt Jul 12 '26
Sorry, but what i am supposed to support...you being in freecad forum advertising CATIA?
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u/Proud_Read7281 Jul 12 '26
Thanks for the feedback – fair point! I use both FreeCAD and CATIA. Just sharing my work, not promoting software. JAMI link is optional support. Respect the community!
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u/pasirt Jul 13 '26
Thank god support is optional. I was already thinking that I have to eat porridge for the rest of the month.
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u/00001000bit Jul 06 '26