In air. This seems like it should be incredibly basic information but I can't find it anywhere.

Terrible diagram 1

I'm trying to figure out how long to make A and B here if I have linear actuator of length C (extended = 2C) in order to tilt my panels from completely horizontal to vertical so they avoid wind and shed snow respectively when I run up the actuator to the extremes respectively based on sensor input.

Is there a simple formula I can use to plug the length of whatever actuator I settle on to figure A and B out? I know it will have to be a certain minimum and maximum size to work properly and might have to experiment to get an idea of what works in the end, but I'd like a reasonable start point to purchase an appropriate actuator.

I've googled around and decided I'm not smart enough to even come up with the right search criteria, let alone figure this out myself since it's been 35 years since I've used anything except the most basic trig.

This isn't really homework except for the fact that I'm trying to make my home work right.

Edit: seems like if I select A=.75C and solve for B at horizontal, then it always works out. No idea why, but the couple examples I try seem to agree.

Hello lemgineers!

I'm working on designing a claw that can be operated underwater. The plan is to use a linear actuator in a waterproof housing. The main issue is allowing the shaft to slide through without causing a leak. What's the best way to go about this?

Is there any mechanical engineers? What you would wish to know when you were starting learning? What skills and topics you consider the most useful in mechanical engineering?

What is the fastest way to learn mechanical engineering in the nowadays when 3d printers are avaliable to be able to design and make custom clocks, engines, generators?

cross-posted from: https://lemmy.crimedad.work/post/77168

> Just build a replacement nuclear power plant and reuse the water. Right?

!An animation of the world's largest wind turbines

This is the second of two wind turbine posts inspired by this recent good news: https://slrpnk.net/post/7625300

!A graphic comparing the size of various wind turbines

This is the first of two wind turbine posts inspired by this recent good news: https://slrpnk.net/post/7625300

I just started getting interested in synchronous machines, and this channel really did it for me. Great for anyone studying engineering, or anyone interested with a high school/first year university physics background.

>​We determine​d that the probable cause of the collapse of the Fern Hollow Bridge in Pittsburgh, Pennsylvania, was the failure of the transverse tie plate on the southwest leg of the bridge, a fracture-critical member (nonredundant steel tension member), due to corrosion and section loss resulting from the City of Pittsburgh’s failure to act on repeated maintenance and repair recommendations from inspection reports. Contributing to the collapse were the poor quality of inspections, the incomplete identification of the bridge’s fracture-critical members (nonredundant steel tension members), and the incorrect load rating calculations for the bridge. Also contributing to the collapse was insufficient oversight by the Pennsylvania Department of Transportation of the City of Pittsburgh’s bridge inspection program.

The full NTSB summary is here, along with links to more pictures and their full board meeting summary: https://www.ntsb.gov/investigations/Pages/HWY22MH003.aspx

cross-posted from: https://lemmy.crimedad.work/post/56030

> cross-posted from: https://pixelfed.crimedad.work/p/crimedad/664838819785277759 > > > My five year old asked me what calceulus is. > > > > The context is that I'm an engineer and she wanted to know what I learned in engineering school, so I said calculus. (In my case, I only made it to pre-calc in highschool.) I swear I'm not the type of parent to try and push this stuff on her. I said it's about understanding how things change and then I tried to illustrate it. I'm open to suggestions on how I could answer her better. > > > > \#calculus #engineering #parenting > > > > @[email protected]

I'm thinking of just adding a potentiometer to a car headlight kit, this serves two purposes, 1. Allows me to have bright ass lights in place of my shitty Prius lights on long country roads while letting me turn down the brightness to not blind people in front of me. And 2: I think this would be a fun project to learn a little more about electronics and car mods.

So far I think I would just need the light kit and a potentiometer to use as a control interface, and maybe some sort of transistor with a heatsink, and possibly a diode to prevent reverse voltage damage. I'm not sure about the heatsink but I know that LED lights being so efficient use almost all of their energy on light, I'm just not sure what will happen to that energy if throttled, making me think it may possibly come off as heat in the transistor.

What do you all think? Doable?

Edit: consensus seems to be it's not practically feasible, do what I think I'll end up doing is just upgrading my brights specifically so I can have a dumbed down version of the same thing

cross-posted from: https://lemmy.world/post/11869824

> A 28-ton, 1.2 MW tidal kite is now exporting power to the grid::undefined

Under structural-only DP loading, a certain amount of deflection is allowed, and a certain amount of post-loading set displacement (permanent deformation) is allowed. Under the DP (design pressure) system, DP ratings are defined differently for structural, water leakage, and air leakage tests. This is a structural only test, so it is not mandatory to maintain a water or airtight seal during or after the load is performed, it simply must not break either the frame, the door, or the glass.

I'm not sure if this unit was a pass or a fail. It at least didn't break.

This two-panel patio door unit has an astragal on the inactive (non-handled) panel with shoot bolts into the head and sill. The active (handled) panel has no shoot bolts in this design, and acts more like a traditional door system.

I believe this was a DP50 structural test rating, equivalent to a 200mph wind. DP is gradually being replaced by the PG rating system which also includes air and water leakage during and after loading in a single unified test definition.

Earlier today, Scottish adventurers Chris and Julie Ramsey were finally able to announce their completion of the nine-month, 17,000-mile "Pole To Pole EV" expedition, the world's first drive from the 1823 Magnetic North Pole to South Pole.

Other links:

https://expeditionportal.com/what-the-pole-to-pole-expedition-wants-you-to-know-about-long-term-ev-travel/

https://poletopoleev.com/

https://global.nissannews.com/en/releases/north-pole-to-south-pole-with-nissan-ariya

cross-posted from: https://feddit.nl/post/7396832

> Source: https://www.world-nuclear-news.org/Articles/In-Pictures-Hinkley-Point-C-polar-crane-installed > > You want to open the source for this.

This quick video by Steve Mould has a neat visualization of metal grain structure.

This display shows stages of forming a German World War I helmet, from a flat blank to finished product.

More information is available at the source: https://rarehistoricalphotos.com/stahlhelm-helmet-making-process-1916/

A friend recently pointed out that, despite most microwave ovens having a Popcorn function, most bags of popcorn specifically say NOT to use that function. It got me wondering how the Popcorn button works (or doesn't work). Apparently there are several different approaches in common use.

Basic method: Microwave on full power for a set amount of time. With clumsy designs like this I'm not surprised the popcorn sellers would discourage using the Popcorn button.

Improved method 1: Have the user enter the weight of the popcorn bag. The microwave adjusts the cooking time accordingly. Better, but still not great.

Improved method 2: Add a humidity sensor to detect the humidity change when the bag bursts open. Much better; now we have a real-time feedback mechanism.

Improved method 3: Add a microphone to listen for the time between pops, just like humans do. I had no idea this was a real thing, but apparently it has existed for years. For example, Whirlpool calls its implementation "AccuPop."

Does anyone have another clever idea to add to the list?

This video has some fantastic demonstrations of how sewing machines work. If you're mechanically inclined then it's definitely worth a watch. The mechanisms that grab, twist, and pull the thread are wonderfully clever and elegant.

The dark autumn evenings reminded me of a particular street light in my neighborhood that's an awful purple color. I finally dug into what causes that. The "white" LEDs are really blue LEDs with a phosphor-based coating on the lens. The coating is excited by the blue light and emits other wavelengths, approximating white light. If the phosphor coating degrades or delaminates then more blue light escapes, making the overall light look more blue-violet.

The post image is from an entry on the Dark Sky Consulting blog.

This recent research paper has some pictures of the actual failure on LEDs.

I'm looking for a book (preferably eBook) which explains one or more engineering projects in great detail.

Anyone have any recommendations?

The original design of the Sydney opera house featured roof sections with unique curves. This caused two major problems: (1) the structural analysis was very difficult, and (2) it made construction more expensive since they could not reuse construction details among the roof sections. Eventually the engineers realized they could approximate the roof sections as segments from a single sphere. This greatly improved both problems.

This post inspired by a recent episode of the Cautionary Tales podcast. I never knew what a messy project the opera house had been.

You really have to watch the video in the linked URL to appreciate this little guy.

Archive link for those who prefer it.

Posting a second picture that shows and earlier stage in the process. Multiple charges ignite to remove the canopy from a CF-18 Hornet immediately before the pilot ejects. Photo from ejectionsite.com, which has more info on the incident.

A post on NCD sent me down a rabbit hole reading about ejection seats. Do we have anyone here who can share some first-hand knowledge about the designs? I didn't fully appreciate these products before: thousands of parts, multiple precisely timed pyrotechnic charges, and big consequences for failure. That sounds like a very stressful development project.

The picture above is a British pilot ejecting from his Harrier in Afghanistan in 2009. He was lucky and was able to resume flying.

cross-posted from: https://lemmy.sdf.org/post/604604

> A sort of museum style tour of some jet engine compressors at a repair shop.

The valve core contains a specially designed wax. The wax expands as it is heated, forcing the valve open and allowing engine coolant to flow to the radiator. When the wax cools and contracts the valve is closed by a return spring.

More modern cars have a "map controlled" thermostat. These incorporate a heating element to melt the wax prematurely if the engine computer demands more cooling.

Here is the full video with narration.

And credit to Jalopnik for the animated gif.

I wonder how many people understand the planning and work that goes into making hiking trails and shelters for us weekend warriors. For example, here's a sample trail project package following the US Forest Service's standard plans and specifications. A trail is so much more than a strip of bare ground.

The image is a classic plan for an Adirondack shelter. They are common in the forests of New York and along the Appalachian Trail.

cross-posted from: https://lemmy.world/post/3895697

> cross-posted from: https://kbin.social/m/[email protected]/t/384191 > > > Tesla is facing issues with the bare metal construction of the Cybertruck, which Elon Musk warned was as tricky to do as making Lego bricks

I had an idea a little while ago that tunnel boring machines should just keep going. Think of all the tunnel we could have if all the TBMs just never stopped. We could have an ever growing tunnel network that could be tapped into as needed.