8 ms·

Army Dissects Black Hawk Helicopter, Scans Parts for 3D Printing

69 points by dfsegoat 6y ago

IanDrake 6y ago
This seems like a surprisingly bad idea. I would think the vendors' engineers would be able to identify the parts that qualify to be 3d printed, given how well the expected material characteristics match what the printer could produce.
- ehutch79 6y ago
  If nothing else, they could provide the cad files. These arn't irregular shapes. You can draw them from the part if you need to
- MR4D 6y ago
  From the article: “But digital models simply don’t exist for vast inventories of older parts, some dating back decades.” I presume that this has something to do with their approach.
  - FPGAhacker 6y ago
    Seems amazing to me that this method would be more cost effective or even just plain effective vs scanning and interpreting paper drafts/blueprints.
    - grandinj 6y ago
      Because actually finding blueprints that reliably match what the helicopter is actually using can be a real problem that can take far longer, will __still__ require you to cross-check against the part because of human error :-)
- varikin 6y ago
  That would be the most economical, but it might be bureaucratically easier for a general to tell a unit to figure this out all in-house than deal with the vendor which may need new contracts to ask for these details.
- neckardt 6y ago
  My guess is that this might be a way to get spare parts for a helicopter in case they break. A family friend who worked on antique cars would often run into the problem where a specific piece broke and he needed to find it replaced. Finding the exact part for a 1970s Porsche is not only difficult, but also incredibly expensive. Having a 3D model of the specific part and just printing it would have been not only far faster but orders of magnitude cheaper. The exact material could just inferred from the broken part or a stronger material could be selected out of caution. I hope their plan isn't to 3D print safety critical parts like the rotor blades, that would certainly end poorly in the way you mention.
rektide 6y ago
I saw this making the rounds today, even though it's evidently old news, about the b1 bomber being disassembled/scanned. Here's an article on the subject from late April 2020: https://www.thedrive.com/the-war-zone/33151/air-force-sends-full-b-1b-airframe-from-boneyard-to-kansas-to-create-its-digital-twin https://www.thedrive.com/the-war-zone/33151/air-force-sends-...
systemvoltage 6y ago
Media loves talking about 3D Printing primarily due to its click ratio and viewership. As an mechanical engineer, I've had experience developing aircraft stages and frames - the whole premise of 3D printed parts going into an aircraft from airworthiness perspective is flat out insane.
- ethagknight 6y ago
  I believe you, but please go on and tell us why
  - systemvoltage 6y ago
    This was 10+ years ago but the process is roughly as follows: Requirements of loads and flight envelopes are first provided to us (I was employed in a stress analysis group). The parts that I worked on weren't "new" per se, these were modifications to existing parts to comply to new loads or new materials, fasteners etc. Once envelopes + safety factors are set, we literally sketch out basic FBD (free body diagrams) along with shear-moment diagrams depending on the type of the part. You know the kind of diagrams you had to do in Statics class in University. Most of us knew the appendix formulas and many other empirical results by heart, and some of the guys at work were total nerds. They knew every possible cross sectional moment of inertia formulas, etc. It was really humbling. You'd think that aircraft industry some slow moving folks, but it couldn't be more false. The discipline was astounding. Then we consult existing parts directory, fastener books and materials for conceptual design. During the first conceptual design review (CDR), Principal engineers (depending on how critical this part is) get involved and provide us feedback. Post CDR, we send out parts to our FEA dept (mostly part time workers, some of them even commercial pilots) that get the models from the drafting department (Catia V4 at the time) and run some discretization scripts, they are pretty versed on how fine the mesh should be, but everything must be documented. Sensitivity study against mesh size needs to be proven. Converged models are sent back to us, we test it against intuition, and theoretical predictions (but not always). Detail design: Flange thickeness to thread pitch is set in stone, about 1800 fastener choices are narrowed down to a few, cost implications are non-existent, so most of the times weight is king. Coatings if any are specified. Prototypes are made by our supplier, GD&T red marks are fixed. Goodman diagram is consulted for fatigue studies, and sometimes even simulated in the FEA model. Same with creep and crack propagation studies. Detail Design review takes place and we are blessed by principal engineer. If it is an external part with any sort of interaction with the airflow, flutter dynamics to CFD guys are called, I honestly never worked on any farrings or anything affecting flight dynamics. Then comes the guaging (where to put rosette and stress gauges) and ground test certification process. Prototypes are tested against real world conditions and failures. Depending on the part, various tensile strength tests are conducted and sometimes with simulated internal cabin pressure. Not all parts were tested though. All in all, it takes forever to make a part in an airplane. My memory is fading so I can't recall everything. It was a lot of paperwork and documentation. We took that seriously. Having designed parts in an airplane, I just can't take 3D printing seriously. You wouldn't believe the kind of work that goes into designing parts from composites - that was a new thing at the time when I was in the industry.
golem14 6y ago
I wonder how this relates to "right to repair" topics.
nickpinkston 6y ago
I hope "3D scan" means "use CMMs, CT capture, x-ray spectral alloy analysis, profilometers, etc. to reverse engineer the components."
lopmotr 6y ago
I'm curious why they don't make 3D models from the original drawings. Maybe they're lost or kept by the manufacturers? By only measuring existing parts, they wouldn't know the tolerances or loads and would have to kind of re-engineer that missing information.
- hashtagmarkup 6y ago
  With a $693,058,000,000 annual budget, might as well just make everything out of titanium. I'm assuming the original drawings weren't used for the same reason you can't trust most contractors documentation. Emergency bugfixes get pushed to production.
  - lopmotr 6y ago
    Then how do they make conventional replacement parts? Somebody must know the dimensions, tolerances, materials, etc.
- dotancohen 6y ago
  Not to mention wear and deformation. Are the landing gear of that particular UH60 bent in the slightest? Has the throttle lever raceway worn? How much damage did the door slamming on some GI's M4 do to the sheet metal?
musicale 6y ago
This will be helpful for any army that wants to manufacture them.
lifeisstillgood 6y ago
What strikes me is that we are reaching "mass manufacturing" limits (or possibly internal combustion engine limits. Possibly both. I have a nice modern car, and it stopped working the other day. And I had absolutely no idea what was wrong. No way to diagnose and no conceptual framework. Military hardware (I am guessing) cannot be as fragile as my nice car, so it must now be lagging behind the cost benefit curve of commercial car production - all the efficiency gains Ford makes must get lost as they cannot risk the fragility. Additionally military hardware is really a special snowflake - lots of highly specific not really available commercially parts. So military hardware must be desperate for actually working 3d printing / one off manufacturing - it solves the cost problem and the special snowflake problem. So I am guessing the DoD will be a heavy investor in all things additive manufacturing for a decade ? Am Inway off base ?
lmilcin 6y ago
Inherent in every part is tolerances, details of finishes, requirements for strength, etc. You can't find those things through 3D scans. At best this is publicity stunt.
mensetmanusman 6y ago
That is some valuable data.

69 points by dfsegoat 6y ago

This seems like a surprisingly bad idea. I would think the vendors' engineers would be able to identify the parts that qualify to be 3d printed, given how well the expected material characteristics match what the printer could produce.

ehutch79 6y ago
If nothing else, they could provide the cad files. These arn't irregular shapes. You can draw them from the part if you need to
MR4D 6y ago
From the article: “But digital models simply don’t exist for vast inventories of older parts, some dating back decades.” I presume that this has something to do with their approach.
- FPGAhacker 6y ago
  Seems amazing to me that this method would be more cost effective or even just plain effective vs scanning and interpreting paper drafts/blueprints.
  - grandinj 6y ago
    Because actually finding blueprints that reliably match what the helicopter is actually using can be a real problem that can take far longer, will __still__ require you to cross-check against the part because of human error :-)
varikin 6y ago
That would be the most economical, but it might be bureaucratically easier for a general to tell a unit to figure this out all in-house than deal with the vendor which may need new contracts to ask for these details.
neckardt 6y ago
My guess is that this might be a way to get spare parts for a helicopter in case they break. A family friend who worked on antique cars would often run into the problem where a specific piece broke and he needed to find it replaced. Finding the exact part for a 1970s Porsche is not only difficult, but also incredibly expensive. Having a 3D model of the specific part and just printing it would have been not only far faster but orders of magnitude cheaper. The exact material could just inferred from the broken part or a stronger material could be selected out of caution. I hope their plan isn't to 3D print safety critical parts like the rotor blades, that would certainly end poorly in the way you mention.

rektide 6y ago

I saw this making the rounds today, even though it's evidently old news, about the b1 bomber being disassembled/scanned. Here's an article on the subject from late April 2020: https://www.thedrive.com/the-war-zone/33151/air-force-sends-full-b-1b-airframe-from-boneyard-to-kansas-to-create-its-digital-twin https://www.thedrive.com/the-war-zone/33151/air-force-sends-...

systemvoltage 6y ago

Media loves talking about 3D Printing primarily due to its click ratio and viewership. As an mechanical engineer, I've had experience developing aircraft stages and frames - the whole premise of 3D printed parts going into an aircraft from airworthiness perspective is flat out insane.

ethagknight 6y ago
I believe you, but please go on and tell us why
- systemvoltage 6y ago
  This was 10+ years ago but the process is roughly as follows: Requirements of loads and flight envelopes are first provided to us (I was employed in a stress analysis group). The parts that I worked on weren't "new" per se, these were modifications to existing parts to comply to new loads or new materials, fasteners etc. Once envelopes + safety factors are set, we literally sketch out basic FBD (free body diagrams) along with shear-moment diagrams depending on the type of the part. You know the kind of diagrams you had to do in Statics class in University. Most of us knew the appendix formulas and many other empirical results by heart, and some of the guys at work were total nerds. They knew every possible cross sectional moment of inertia formulas, etc. It was really humbling. You'd think that aircraft industry some slow moving folks, but it couldn't be more false. The discipline was astounding. Then we consult existing parts directory, fastener books and materials for conceptual design. During the first conceptual design review (CDR), Principal engineers (depending on how critical this part is) get involved and provide us feedback. Post CDR, we send out parts to our FEA dept (mostly part time workers, some of them even commercial pilots) that get the models from the drafting department (Catia V4 at the time) and run some discretization scripts, they are pretty versed on how fine the mesh should be, but everything must be documented. Sensitivity study against mesh size needs to be proven. Converged models are sent back to us, we test it against intuition, and theoretical predictions (but not always). Detail design: Flange thickeness to thread pitch is set in stone, about 1800 fastener choices are narrowed down to a few, cost implications are non-existent, so most of the times weight is king. Coatings if any are specified. Prototypes are made by our supplier, GD&T red marks are fixed. Goodman diagram is consulted for fatigue studies, and sometimes even simulated in the FEA model. Same with creep and crack propagation studies. Detail Design review takes place and we are blessed by principal engineer. If it is an external part with any sort of interaction with the airflow, flutter dynamics to CFD guys are called, I honestly never worked on any farrings or anything affecting flight dynamics. Then comes the guaging (where to put rosette and stress gauges) and ground test certification process. Prototypes are tested against real world conditions and failures. Depending on the part, various tensile strength tests are conducted and sometimes with simulated internal cabin pressure. Not all parts were tested though. All in all, it takes forever to make a part in an airplane. My memory is fading so I can't recall everything. It was a lot of paperwork and documentation. We took that seriously. Having designed parts in an airplane, I just can't take 3D printing seriously. You wouldn't believe the kind of work that goes into designing parts from composites - that was a new thing at the time when I was in the industry.

golem14 6y ago

I wonder how this relates to "right to repair" topics.

nickpinkston 6y ago

I hope "3D scan" means "use CMMs, CT capture, x-ray spectral alloy analysis, profilometers, etc. to reverse engineer the components."

lopmotr 6y ago

I'm curious why they don't make 3D models from the original drawings. Maybe they're lost or kept by the manufacturers? By only measuring existing parts, they wouldn't know the tolerances or loads and would have to kind of re-engineer that missing information.

hashtagmarkup 6y ago
With a $693,058,000,000 annual budget, might as well just make everything out of titanium. I'm assuming the original drawings weren't used for the same reason you can't trust most contractors documentation. Emergency bugfixes get pushed to production.
- lopmotr 6y ago
  Then how do they make conventional replacement parts? Somebody must know the dimensions, tolerances, materials, etc.
dotancohen 6y ago
Not to mention wear and deformation. Are the landing gear of that particular UH60 bent in the slightest? Has the throttle lever raceway worn? How much damage did the door slamming on some GI's M4 do to the sheet metal?

musicale 6y ago

This will be helpful for any army that wants to manufacture them.

lifeisstillgood 6y ago

What strikes me is that we are reaching "mass manufacturing" limits (or possibly internal combustion engine limits. Possibly both. I have a nice modern car, and it stopped working the other day. And I had absolutely no idea what was wrong. No way to diagnose and no conceptual framework. Military hardware (I am guessing) cannot be as fragile as my nice car, so it must now be lagging behind the cost benefit curve of commercial car production - all the efficiency gains Ford makes must get lost as they cannot risk the fragility. Additionally military hardware is really a special snowflake - lots of highly specific not really available commercially parts. So military hardware must be desperate for actually working 3d printing / one off manufacturing - it solves the cost problem and the special snowflake problem. So I am guessing the DoD will be a heavy investor in all things additive manufacturing for a decade ? Am Inway off base ?

lmilcin 6y ago

Inherent in every part is tolerances, details of finishes, requirements for strength, etc. You can't find those things through 3D scans. At best this is publicity stunt.

mensetmanusman 6y ago

That is some valuable data.