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A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

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Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#101

Post by seg_lol »

benatkin wrote: post #80
elicash wrote: post #57

Earlier quoted context omitted.

In what way is this like vibe-coding -- or do you just mean both are bad? According to the report: > The aircraft owner who installed the modified fuel system stated that the 3D-printed induction elbow was purchased in the USA at an airshow, and he understood from the vendor that it was printed from CF-ABS (carbon fibre – acrylonitrile butadiene styrene) filament material, with a glass transition temperature3 of 105°…

The person who coined the term vibe coding is now doing a soylent-like [1] experiment where he only will read content that has been regurgitated by an AI [2], so yes I think it's a fair characterization of "vibe coding". 1: https://nymag.com/intelligencer/2014/10/soylent-creator-hack... 2: https://x.com/karpathy/status/1990577951671509438

He is gonna get slopabetes!

Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#102

Post by Centigonal »

It's important to note the plane is a Cozy Mk IV, which is an experimental light aircraft that is built at home out of foam and fiberglass by following instructions you get online. The design is very good, and hundreds have been flown over the last ~35 years, but Cozy pilots are the aviation equivalent of people who run Arch Linux as their daily driver; many of them are tweaking their aircraft with some frequency.

This isn't a case of an established aircraft manufacturer cutting corners on a part; it's probably some small maker who made this part out of the wrong materials. It's a little shocking that neither the maker nor the buyer of this part thought to either stick it in an oven or run it with the engine on the ground to guarantee it could hold up to the expected intake air temps. I'm glad the pilot made it out with only mild injuries.

edit: here's a fun video from a Cozy pilot in case you're curious about the plane and the people who fly them: https://www.youtube.com/watch?v=Ipqmb09wbSQ

Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#103

Post by ahepp »

Centigonal wrote: post #102

It's important to note the plane is a Cozy Mk IV, which is an experimental light aircraft that is built at home out of foam and fiberglass by following instructions you get online. The design is very good, and hundreds have been flown over the last ~35 years, but Cozy pilots are the aviation equivalent of people who run Arch Linux as their daily driver; many of them are tweaking their aircraft with some frequency. Th…

Do we know whether the part was made out of spec, or whether the spec specified inappropriate materials?

Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#104

Post by phkahler »

fudged71 wrote: post #27

This is the mechanical equivalent of vibe coding. 3D printing itself isn't exactly to blame but the negligence of the company that created and sold this part and omitted it's use from an inspection. Just because a part has the shape of an engineered part does not make it compatible, strong, safe, and fit for purpose. This part could have likely been fine if it used a different material such as Ultem.

>> This part could have likely been fine if it used a different material such as Ultem.

Maybe, but FDM printed parts are still much weaker than molded parts. We tried printing some coolant pump housings once during development. They worked fine until the pressure went up and then layers separated and someone got to clean the lab. At least an air intake is gonna have negative pressure which might help hold the layers together.

Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#105

Post by averynicepen »

elicash wrote: post #57
fudged71 wrote: post #27

This is the mechanical equivalent of vibe coding. 3D printing itself isn't exactly to blame but the negligence of the company that created and sold this part and omitted it's use from an inspection. Just because a part has the shape of an engineered part does not make it compatible, strong, safe, and fit for purpose. This part could have likely been fine if it used a different material such as Ultem.

In what way is this like vibe-coding -- or do you just mean both are bad? According to the report: > The aircraft owner who installed the modified fuel system stated that the 3D-printed induction elbow was purchased in the USA at an airshow, and he understood from the vendor that it was printed from CF-ABS (carbon fibre – acrylonitrile butadiene styrene) filament material, with a glass transition temperature3 of 105°…

3D printing is to mechanical engineering what vibe coding is to computer science.

With the rise of accessible 3D printers that can print engineering materials, there are a lot of people who try to create functional parts without any engineering background. Loading conditions, material properties, failure modes, and fatigue cycling are all important but invisible engineering steps that must be taken for a part to function safely.

As a consumer with a 3D printer, none of this is apparent when you look at a static, non-moving part. Even when you do start to learn more technical details like glass transition temperature, non-isotropic strength, and material creep, it's still not enough to cover everything you need to consider.

Much of this is also taught experimentally, not analytically - everyone will tell you "increasing walls increases strength more than increasing infill", but very few can actually point to the area moment of inertia equation that explains why.

3D printing has been an incredible boon for increasing accessibility for making parts in small businesses, but it has also allowed for big mistakes to be made by small players. My interpretation is the airshow vendor is probably one of these "small businesses".

Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#106

Post by Centigonal »

ahepp wrote: post #103
Centigonal wrote: post #102

It's important to note the plane is a Cozy Mk IV, which is an experimental light aircraft that is built at home out of foam and fiberglass by following instructions you get online. The design is very good, and hundreds have been flown over the last ~35 years, but Cozy pilots are the aviation equivalent of people who run Arch Linux as their daily driver; many of them are tweaking their aircraft with some frequency. Th…

Do we know whether the part was made out of spec, or whether the spec specified inappropriate materials?

The spec is fiberglass, which has better thermal resistance.

Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#107

Post by phoronixrly »

Centigonal wrote: post #102

It's important to note the plane is a Cozy Mk IV, which is an experimental light aircraft that is built at home out of foam and fiberglass by following instructions you get online. The design is very good, and hundreds have been flown over the last ~35 years, but Cozy pilots are the aviation equivalent of people who run Arch Linux as their daily driver; many of them are tweaking their aircraft with some frequency. Th…

[flagged]

Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#108

Post by PunchyHamster »

phkahler wrote: post #104
fudged71 wrote: post #27

This is the mechanical equivalent of vibe coding. 3D printing itself isn't exactly to blame but the negligence of the company that created and sold this part and omitted it's use from an inspection. Just because a part has the shape of an engineered part does not make it compatible, strong, safe, and fit for purpose. This part could have likely been fine if it used a different material such as Ultem.

>> This part could have likely been fine if it used a different material such as Ultem. Maybe, but FDM printed parts are still much weaker than molded parts. We tried printing some coolant pump housings once during development. They worked fine until the pressure went up and then layers separated and someone got to clean the lab. At least an air intake is gonna have negative pressure which might help hold the layers…

but it didn't fail because of stress. It failed exactly because it was made from wrong material. If the exact same part was injection molded from the same material it would melt too

Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#109

Post by seemaze »

elicash wrote: post #57
fudged71 wrote: post #27

This is the mechanical equivalent of vibe coding. 3D printing itself isn't exactly to blame but the negligence of the company that created and sold this part and omitted it's use from an inspection. Just because a part has the shape of an engineered part does not make it compatible, strong, safe, and fit for purpose. This part could have likely been fine if it used a different material such as Ultem.

In what way is this like vibe-coding -- or do you just mean both are bad? According to the report: > The aircraft owner who installed the modified fuel system stated that the 3D-printed induction elbow was purchased in the USA at an airshow, and he understood from the vendor that it was printed from CF-ABS (carbon fibre – acrylonitrile butadiene styrene) filament material, with a glass transition temperature3 of 105°…

In the sense that production costs have undercut evaluation costs permitting a cadre of un(der)-qualified entrants to the space.

Not a new story in the progression of human endeavors; see the printing press, perspective painting, digital photography, residential construction.

Re: A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

#110

Post by Centigonal »

phoronixrly wrote: post #107
Centigonal wrote: post #102

It's important to note the plane is a Cozy Mk IV, which is an experimental light aircraft that is built at home out of foam and fiberglass by following instructions you get online. The design is very good, and hundreds have been flown over the last ~35 years, but Cozy pilots are the aviation equivalent of people who run Arch Linux as their daily driver; many of them are tweaking their aircraft with some frequency. Th…

[flagged]

General aviation (and especially experimental light aircraft) is not a particularly safe hobby. This pilot literally put his life in the hands of a 3D printed part someone sold him at an airshow. Pilots can and do "brick" their planes as a result of "innovative" approaches to repairs, upgrades, and maintenance. Luckily, much of the time these errors are caught before the plane gets off the ground.
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