I want to say the 787 also has composites in the wings, but I’m not certain. It does, however, bend quite a lot during takeoff. But I think most wings do too, but controlled so it doesn’t cause fatigue cracking at the wing roots. A composite wing wouldn’t have the same fatigue failure mechanism.
In the case of aircraft fuselage – using the Boeing 787 as the prime example – the pressurized cabin means that the airplane is basically a balloon, as the pressure inside is typically something akin to being at 6000-8000 ft MSL (~2-3 km) but the outside air pressure is something like 32,000-38,000 ft MSL (~10-12 km).
Expressed another way, the delta between 6000 ft pressure and 38,000 ft pressure is about 600 hPa, or roughly 60% of sea level pressure. Since 1 Pascal is 1 Newton per square meter, and if we say an aircraft door is 2 sq meters, the force trying to push the door open at cruise is 120,000 Newtons, or the equivalent gravitational force expressed an object measuring 6 tonnes!
As a balloon-like tube, the 787 fuselage has a lot of similarities with how its fibres are arranged, not unlike the plies that stretch across the tread of a pneumatic bicycle tire.
I actually have seen wooden wagons careening around pretty good.
Ok, I have to know: what sort of situation would this have been at? Medieval chariot racing?
The exact shrinkage of a green log as it seasons is something like 15% radially, 5% axially and not at all along the grain. If you think about the geometry of that, it’s going to build up quite a lot of stress and spontaneously fail, unless it has been cut and can warp instead. And that’s exactly what you see in old, unsplit logs; they get one big, longitudinal crack that spreads open almost to the center.
I’ve never thought about the shrinkage rate before, but it makes perfect sense that wood would shrink at different rates in different dimensions. Would this also suggest that steam bending of wood is less effective in certain directions?
The fascinating thing is that if you use really basic materials, that’s not exactly true!
You’re absolutely right, and I was more-or-less generalizing, given that modern structures tend to focus on maximizing the tensile strength, such as carbon fibre for fuselage sections. There’s even the combination where tensile strength is used to augment compressive strength, like with tensioned concrete slabs. Honestly, the fact that some steel wires pulling within a piece of concrete makes it stronger is kinda nuts to me.
We’re at a unique juncture where wood is being revisited as a sustainable material, but also because it’s quite interesting if its natural drawbacks can be tamed. The fact that wood bends well before it snaps gives it some very forgiving characteristics, unlike steel which will hold until catastrophically failing.
I suppose if we look more closely at wood, it does in-fact have some tensile strength, as the bottom-side of a heavily-laden beam does stretch. But I’m not material engineer.
Natural cordage has great tensile strength, but ~zero compressive strength and will stretch to laxity over time.
I have to mention that this is precisely why the phrase “you can’t push a rope” exists, for folks not familiar with this expression for an impossible assignment.
Arsenic was also available for that, but it was so toxic they didn’t even want to expose their slaves, and so the Near East moved over time to tin
TIL!
I suppose you could turn a wood ring out of one big log
I once considered this as a thought experiment, just to see if it would work. And my conclusion is that it would be a phenomenal waste of a log to make a solid disc, when a spoked wheel made from conventional, longitudinal boards cut from the same log would yield a satisfactory wheel at greatly reduced material consumption. That said, it may very well be viable for smaller-diameter wheels, where rendering a slender log into boards would result in too much lost material as sawdust.
The origin of the word tyre is that metal band. It’s put on hot, and the compression as it quenches is what holds the entire assembly together.
If I’m not mistaken, this is how steel tires for steel railway wheels are attached. Plus ça change!
I will admit that my pre-1800s wheel knowledge is quite limited, but one thing which is clear from wood as a building material is that it’s mostly used for its compressive strength. That is, the spokes of a wooden wheel are there to only bear weight when directly below the axle. Otherwise, they’re not doing too much.
Some wood wheels do have massively thick spokes which can singularly bear the entire weight from the hub, as the wheel rotates. This makes the rim less important, apart from providing a smooth surface to meet the road.
But other wood wheel designs used a massively thick rim which would hold the circular shape. These designs meant the downward force was spread across multiple spokes (not just the immediate bottom one) and so each spoke could be slightly narrower.
The big innovation with bicycle wheels circa later 1800s is that the spokes are in tension, not compression. And that simultaneously makes the rim into a natural circle while saving rim weight, plus it distributes the load forces across all the spokes, making them all thinner. Add the fact that steel has incredible tensile strength and the result is pencil-thin wires supporting over 100 kg easily. Since material science has blessed us with materials with more tensile strength than compressive stength, this is almost as optimal as it gets, for a wheel with purely vertical loads (near-perfect for bicycles; not as good for automobiles).
The simplest intuitive understanding is to imagine what happens if a bicycle wheel tried to deform at the bottom. If so, three or four spokes will be relieved of tension, but some 30 spokes other would undergo extra tension. And that would work to resist the deformation, returning back to the intended circular shape. Wood wheels have no such restorative feedback loop. Nor can wood wheels spread out an overstress to multiple spokes, and instead would probably collapse the wheel with attendant injuries.
The drawback of the wire spoke wheel is that as the diameter gets larger, the transverse strength will diminish, because the spoke angle from the rim approaches 90 degrees. That is to say, if a bicycle were doing a power-slide, a really tall wheel would run the risk of “dishing” out, where the rim basically slides off-plane from the hub, turning into something like a cone, potentially catastrophically. Old timey penny-farthing bicycles are at the diameter where this is a problem, but fortunately those bikes can’t practically be slid sideways. This is also why cars moved away from spoked wheels, because of this lack of lateral strength.
The other drawback is that the structure is the most efficient (read: saves the most material/weight) when the rim is narrow. But if being paired with a wide tire, then the rim has to be wider and that costs material. Bicycles use “balloon tires” that expand wider than the rim, and those have worked great for even MTB bikes that need the extra tire width. But today’s fatbikes and e-bikes with >4 inch (100 mm) tire widths necessarily require wide rims, and that’s taking efficiency off the table. It’s another reason cars (which need tire width bc they’re so heavy) moved away from spoked wheels.
As for the parallel with barrel making, I think the cooper uses steel/iron bands to bind the barrel together, right? I think I’ve seen steel along the tread of wood wheels, but I don’t know if that’s structural to the wheel or if it’s more like tread to prevent the road from destroying the rim surface.
Let me make sure I understand everything correctly. You have an OpenWRT router which terminates a Wireguard tunnel, which your phone will connect to from somewhere on the Internet. When the Wireguard tunnel lands within the router in the new subnet 192.168.2 0/24, you have iptable rules that will:
So far, this seems alright. But where does the service run? Is it on your LAN subnet or the isolated 192.168.2.0/24 subnet? The diagram you included suggests that the service runs on an existing machine on your LAN, so that would imply that the router must also do address translation from the isolated subnet to your LAN subnet.
That’s doable, but ideally the service would be homed onto the isolated subnet. But perhaps I misunderstood part of the configuration.
Clickbait headline, and the article isn’t exactly filled with substance either. Downvoted because it wasn’t even worth reading, when a simple web search reveals much better resources for folks getting started.
It took me a few reads to internalize everything that you wrote, and it’s food-for-thought for when I level-up to adding another machine to my garage. It does seem that I can wait on the jointer for a long while, and on the thickness planer until my projects start using wider boards or I get really tired of hand planing those.
Good to know that the combo planer/jointer is not exactly optimal, and I’ll have to keep an eye out for either separate machine that happens to be for sale on the used market.
I have no other tool that could take a quarter inch off the thickness of a 10 inch wide board; the only tool I have that is appropriate for this task is my thickness planer.
As it happens, this was precisely what I also had to do for an earlier project, and I ended up using my router table to do it. It was an awful slog of a time, and I hope to never repeat that ever again. Throughout the ordeal, I kept thinking about how a CNC mill would have made quick work of it, but I suspect a used thickness planer is going to be a lot more affordable for me
If a normal bench plane is a chisel wearing a pair of steel toed boots, a shoulder plane is a chisel wearing strappy wedge heeled sandals.
This made me laugh, but was also effective at explaining the difference, as did some more image results that specifically show the iron of each plane.
At last, my collection of 3M Super 77 comes in handy!
Yes, most of what I typically have on hand is dimensional lumber. So it’s already mostly alright, but the surfaces might not all be square and I need to figure out ways to keep those errors from propagating.
to force wagon standardisation on everyone in the empire, to slightly improve hauling efficiency, was not going to be on the agenda
There remains some debate whether the modern railway and and motor vehicle gauges (ie distance between wheels) are direct descendents from the spacing between wagon wheels of the Roman Empire era, usually coming up in response to the nonsensical claim that NASA space shuttle dimensions were restricted by the rail gauge of a tunnel in the Rocky Mountains, due to descending from really old wagon gauges.
But of that debate, one aspect which I find highly plausible is that the earliest wagons would have been built to approximately the same gauge, even though each one would have to be constructed by hand independently. The reason would be for handling, because on smooth ground the gauge doesn’t matter. But on rutted roads, it would be awful to have alternating left and right wheels continually falling into the ruts.
A better situation would be to fit into both the ruts on left and right, then remain there until having to make a turn. Given that wooden wagons and wooden wheels weren’t exactly the most durable of that era, anything to make them last longer would be sensible, I would think.
With regards to wheels specifically, wood wheels are great for loads that are perfectly down the spokes. But the moment a sideways force exists – such as sliding into a rut – the wheel is put into tension along the axle, which is not great. At the very minimum, the (likely) journal bearings would be deeply unhappy. In the worst case, the outside of the wheel (the “tread”, so to speak) could be ripped off, taking the spokes with them and collapsing the entire axle. In the modern day, rarely does anyone have experience with wheel failure but it would be fairly catastrophic.
I might have too much to say about modern wheels, specifically spoked bicycle wheels and pneumatic tires, which are an engineering pinnacle.
A matter of someone having an idea, rather than a restriction of material technologies available.
For this, I look to sci-fi. And dang, now I wonder if the Romans had their own body of sci-fi, and if any of it was accurate in terms of things the Roman Empire – unless it hasn’t actually died yet!!! – would never live to see.
The other aspect is that the road types today don’t equate to what Roman roads were meant for. In modern parlance, we would say that Roman roads are akin to highways, going between major places and prioritized speed and mobility. Basically the Interstate freeways of the day. Durable and all-weather.
But Roman roads don’t really analogize to the sprawling suburban streets of America and other car-obsessed places. For a question about the costs of road vs rail, I wrote that the way freeways are built is still more-or-less recognizable from the Roman approach: dig down and remove soil, add different layers of material, put a smooth-ish surface on top. But today’s suburban and residential asphalt roads are explicitly a product of the availability of cost-cutting technology, where asphalt can basically be laid atop the natural soil.
That allows more road to be laid for cheap, but of a lower quality than highways. And that’s fine for a neighborhood street.
I also wrote about how railways sit on the same construction as Roman roads, but with the benefits of smooth, low-friction running. And I wonder what the Empire would have looked like if they had railways. Not even steam railways, but just horse-drawn railcars that could pull literal tons of material. Would they have expanded their road-building empire with rail as the supply line? Which Roman emperor would have been the first to invade with rail-drawn weapons?
Oh, I see. So a shoulder plane’s blade actually has exposure on three sides, and can cut the bottom and the sides simultaneously?
Ah! That makes much more sense
I figured that a shoulder plane and shooting board would be two disparate tools, but for my own knowledge, I haven’t figured out why exactly a shoulder plane with a shooting board doesn’t work. Is it because a shoulder plane tends to be short?
Thanks for this additional detail! I’m currently leaning on going with the shoulder plane, with intention to add a machine planer in future for dealing with larger material all at once. Would that be a sound plan?
Thank you for the detailed clarification!
In review, it sounds like a shoulder plane would prove its worth for very small, fiddly work that a general-purpose plane couldn’t reach, but it would be slower for flattening the poor stock that I often use. Would this mean a shoulder plane plus a machine planer be a reasonable combination, with the latter introduced later to enable larger-scale flattening?
The body of the plane is square to the sole, making 90° easily achievable by riding the side of the plane on an adjacent 90° surface
This might be the feature which sways my decision, since I think it means I can devise a simple jig for any size of stock by clamping to a known flat surface (or even just a surface that’s more flat than the stock) and guide the shoulder plane that way, to prepare for joining. I didn’t mention in my original post, but I also occasionally do “coarse metalworking” where all the stock I use is already nice and straight and flat, which would make good guiding surfaces for a shoulder plane (on wood lol).
Hmm, I think a nearby recycled building materials store might have exactly this. Do I understand correctly that this offcut would only be used as a smooth, abrasive surface?
I go barefoot because homegym, but I once got the recommendation to look for water shoes. That is, thin shoes with a rubber sole meant for use at the pool. But that also makes them reasonable as a flat sole shoe for gym.