A place to geek out about engineering, fabrication, and design. All disciplines are welcome. Ask questions, share knowledge, show off projects you're proud of, and share interesting things you find.
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The current community banner image is from Lee Attwood on Unsplash.
Shadowgraphs of fluid disturbances around high-velocity vehicles demonstrate how a blunt-bodied vehicle produces a shockwave in front of the vehicle, which allows it to stay cooler during reentry. 1960.
Source: https://rarehistoricalphotos.com/nasa-wind-tunnels-photos/
The 40 x 80-foot wind tunnel at Ames Aeronautical Laboratory, Moffett Field, California. At the time of its construction it was the largest wind tunnel in the world. 1947.
Source: https://rarehistoricalphotos.com/nasa-wind-tunnels-photos/
@[email protected] is doing serious work over at [email protected]
cross-posted from: https://lemmy.ca/post/742529
YouTube Video Full System Tour of my Machine Room
This is a video that I made this spring to explain what's in my machine room and what it does as well as the supporting development and operations hardware in my office.
This is an interesting vehicle concept combining hydrofoils, ground effect flight, and electric motors. The idea is to use hydrofoils to lift the craft above the waves for a smoother takeoff, then fly low using ground effect. Though there's a significant regulatory question: is it an aircraft or a watercraft?
The picture is a 1/4-scale prototype during a test flight in 2022. More pictures are here and an interview with the CEO is here. A full-scale, 12-passenger craft is in the works and slated to fly in 2024, followed by a planned 100-person model. The company claims to already have orders for "over 467" seagliders.
Bertha was custom built to dig the State Route 99 tunnel under Seattle. It dug under the city (off and on) from December 2013 to April 2017.
I'm making mechatronic Dr Octopus arms (they're gonna be pretty sweet), and I'm in the process of prototyping the segments. They'll be roughly 2.5 cm in height, with a 2.5 cm gap from segment to segment, and they need to be attached securely, with smooth rotation on xyz to ≈ 10°. Planning on housing the servos in the base, and running cables down the arms to actuate them. Roughly 24 segments total, with separate control cables for the first 12 and second 12 (so the first half can bend in one direction, and the second half another), along with a drive cable down the center so it can rotate on the z axis. This also means I'll need some empty space running down the center of the segments to run the drive cable and the control cables for the second half, so they don't impede/aren't impacted by the bending of the first half.
As far as I can figure, spherical bearings are my only real option here. As a test, I bought 4 steel spherical bearings from Amazon to connect the segments. And man, I love these things. I'd never handled them before, and they are smooth as butter. Unfortunately, they were like $7/per, and I need around 100 of them. So, slightly more than I'm hoping to spend haha. Aliexpress has them for ≈ $1.50/per, but the shipping is obscenely expensive, and would take like 2 months.
So I'm trying to figure out another option. I'm a member of a local maker's space, so I have access to a bunch of tools (metal shop with lathe, CNC, FDM 3D printers), but still don't think I have a great solution.
The tools for making these the right way are obscenely expensive. I'm thinking I could machine the race in two halves and weld/clamp them around the ball, which would be a ton of work, and wouldn't be as smooth, but would probably be sufficient.
I could 3D print them, but I can't figure out a process that would be as smooth as I want. They'd need to be filled/sanded, probably coated with a dry lubricant. But the filling/sanding process would introduce tolerance issues, and I can't afford to have slop with how the cables will work.
Anyone have any insights here to help me out? Thanks!
New turbine blades being installed at the Ice Harbor Dam in Washington state, USA in 2018. The new blade design is supposedly less likely to harm young migrating salmon, which are sometimes pulled through the turbines.
More information on the project is here.
The image is from the Army Corps of Engineers (Source)
A Francis turbine runner being installed at Grand Coulee Dam, Washington state, USA. The damn has 27 Francis turbines of various sizes, plus 6 additional pump-generators, for a combined electrical generating capacity of 6,809 megawatts.
Photo from the US Bureau of Reclamation (Source)
A robotic system known as DamBot™ operates near closure gates at Blue Mountain Dam, Arkansas in October 2020. Dambot™ takes the human element out of a dangerous but necessary U.S. Army Corps of Engineers (USACE) maintenance task. The cutting-edge technology has been successfully tested and stands poised to change the course of closure gate assessments, while also safeguarding USACE team members. (U.S. Army Corps of Engineers photo)
Source: https://www.usace.army.mil/Media/Images/igphoto/2003038049/
NASA test video here.
These things look cool as hell. Any aerospace folks here who can tell us more about them?
Does anyone have any thoughts on this failure? I'm curious what the typical inspection schedule and process is for a roller coaster like this.
I'm also curious about the root cause of the failure. I have a guess, but it would be interesting to see an actual failure report. I don't expect to see it in the news, though.
Here is a video of the crack moving as roller coaster cars go by.
Someone also got a photo of the crack a week prior before it had fully propagated through the support.
From an article at gCaptain.
LNG tanks like this hold liquefied natural gas at approximately −163 °C (−261 °F) during ocean voyages.
