3-D PRINTED EXPERIMENTAL ?

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Riggerrob

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The 3D printed building I was thinking of basically had the nozzle pooping out a stream of thick, I assume quick-drying cement. No molds required. What it does require is a big gantry for the nozzle and whatever mechanism keeps feeding the thing, plus whatever equipment is necessary for set up and tear down of the machine. That’s a lot of effort when a truckload of bricks could just show up.

Likewise I think with current tech there’s probably a way to 3D print a human carrying airplane but the only thing it will be good at is being a 3D printed airplane.
Most construction in Vancouver now includes cranes and concrete pumps. Even single-family dwellings often use lighter weight cranes to move materials from trucks on the street in front to where they will be nailed into place. On tall, complex buildings, it is cheaper to pump concrete up to the umpteenth floor than to hire dozens of laborers to hand-bomb it in wheel barrows. I guess that the cost of cranes and concrete pumps is related to the local cost of labor.
 

Riggerrob

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On the moon, would concrete dry too fast?
Would the water in concrete evaporate too quickly ... in the thin (read non-existent moon's atmosphere?
Would you need to keep the concrete enclosed (e.g. inside a concrete pump and hoses) until it is "laid?"
 

proppastie

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1600Mpa laser sintered 3 d print titainium
their material compares to other printed metal parts but does not compare to strengths of traditional metals....hopefully in the future they might post heat treat with the lazer after the meld because trying to heat-treat a wing is going to take a large furnace.
 

Rik-

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By aircraft standards, rotomolding is neither light nor strong. Fine for fuel tanks, not much else.
It can be as strong as you design it and it's specific weight is not that heavy. It's just a thin layer of plastic, durable, somewhat abrasive resistance and fluid tight.
 

addaon

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Unreinforced polyethylene, and other common rotomolded plastics, have a low specific strength. You can make it stronger, but you’ll never get a reasonable strength to weight without heavily modifying the process to including reinforcement.
 

proppastie

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be as strong as you design it

polyethylene,
there is carbon tow reinforced 3D printing material.....however programming the part for continuous fiber laydown is an issue, and the poor strength of the plastic seems to be currently limiting fabricated part strength especially between layers and in the transverse direction according to what I have read.
 

Rik-

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Unreinforced polyethylene, and other common rotomolded plastics, have a low specific strength. You can make it stronger, but you’ll never get a reasonable strength to weight without heavily modifying the process to including reinforcement.
They can rotomold the shape and inject a foam to add rigidity to it making it a plastic over foam rather than a glass over foam home built design.
 

jedi

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It can be as strong as you design it and it's specific weight is not that heavy. It's just a thin layer of plastic, durable, somewhat abrasive resistance and fluid tight.
Isn't it difficult to control the thickness of the "thin layer" thus making the product heavier than necessary depending on the shape and physical requirements. Works well for round pipe, not so well for complex shapes like an access door, an engine cowl cover or foam core large aerodynamic fairing.
 
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Victor Bravo

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You can make an airplane out of poured concrete and rebar, or Molt Taylor's paper and glue, or the Professor's Gilligan's Island bamboo and palm fronds. I have personally eaten a chocolate airplane, and airplane cookies. I'm sure you could do a full size airplane that way if you really wnted.

But why?

The typical 3D printed plastics that are available today are just nowhere near the right material to build a structural airframe out of. The 3D sintered or melted metal printed stuff just entering use now can certainly-possibly do it in the near future, but if Boeing and Grumman and Lockheed aren't spending trillions in taxpayer money to do it then this tells me it's just not practical yet... even with a blank check.

What IS practical right now is using this incredible technology for certain parts of building an airplane that would otherwise be huge time-suckers - even if the printed part isn't in the finished airframe. Layup molds, Wing build jigs, Tack weld and riveting jigs for tube fuselages, Cement female molds to hammer aluminum cowlings and fairings into, Cement molds to rubber-press wing ribs into, etc.

A set of printed rib jigs would allow all 836 different size and shape wing ribs to be built out of tiny sticks for the elliptical wing on that magnificent Heinkel He 70 replica you've been planning, or turning that daydream Horten H-IV sailplane into a weekend project.

800px-Heinkel_He.70_right_resr_NACA-AC-183.jpg


horten_ho_iv_a_flying_wing_sailplane-40276.jpg
 
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mcrae0104

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On the moon, would concrete dry too fast?
Would the water in concrete evaporate too quickly ... in the thin (read non-existent moon's atmosphere?
Would you need to keep the concrete enclosed (e.g. inside a concrete pump and hoses) until it is "laid?"
On this planet, we have a number of ways of dealing with the hydration rate of concrete (outside the scope of this forum) but on the moon I'd be more worried about getting the water there to begin with.
(Sorry, I thought we were we talking about homebuilt airplanes; did I get distracted with something silly like casting concrete in outer space?)
 

AdrianS

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That is a very limited production run, with the cheap cars 7 figures.

Tim
Agreed. And they're replacing aluminium with titanium, so they can get away with lower UTS than the best titanium forgings...
but that was 2018, and costs are coming down.

I believe that part of the reason they went 3d printing (apart from the wow factor) is that they can optimise to a more complex shape without as much difficulty in manufacturing it.

For example, I think some of the hydraulic plumbing is integral to the caliper.
 
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