Guns and Ammo Thread

[Beetlegeuse]

I've seen prottype Inconel rotors and turbines made via additive matching but thinner geometry tended to distort @ higher pressures. I would have to see a sectional or detail view of the baffles unless they went with a monolithic design , which would make sense if they're printing....

The first all-inconel can I'm aware of was the 3-d printed jobbie from Thermal Defense Solutions. They claim its baffle design was ginned up by computer modeling on a supercomputer by Oak Ridge national labs. So they naturally claimed it was the quietest and most sophisticated design in existence.



It bears more than passing resemblance to AAC's baffle, which was regarded as the best design in use. I don't see any "clipping," which was one of AAC's key features, but maybe that means AAC's wasn't the best design after all.

[Beetlegeuse]

I tried to do a simple edit of a few typos and royally screwed this post up, but I think it's fixed now. Sorry for the foul-up.
[/apology]

Sig-Sauer is now making a 3d-printed Ti can. Just a teaser so far and few significant details, no weight specs or price. Titanium has a modulus of stretch that is unusually high for a 'hard' metal, which makes it less susceptible to failures due to stress, which hints at a long service life for something subjected to extreme changes in pressure. However, I still want my blast baffle made from inconel because it's more wear-resistant and it's much more common for a suppressor's blast baffle to wear out from years of use than for the suppressor body to rupture from stress fatigue.

Ti and inconel both are notoriously hard to machine so I'm seeing a bright future for 3-d printing of both, especially for pieces parts made from materials that are so difficult to machine but that could benefit from designs utilizing complex curves, like suppressor baffles, and that might be impractical or impossible to make without 3-d printing.


And on a quasi-related note, the Chi-Coms have figured out how to 3-d print gunpowder. Not really gunpowder but it's a firearm propellant based on RDX, the primary explosive constituent in C-4. The point of the 3-d printing is that instead of charging a cartridge with a pile of individual powder granules, you can use a stack of disks of propellant or even print a propellant charge pre-shaped to match the interior of the cartridge case.

The biggest trick of course was printing something from high explosive without exposing it to enough heat to ignite it. In their initial test they fired the same cartridge as used in the A-10 warthog's 30mm GAU-8 cannon and got about half of the GAU-8's customary muzzle velocity. Which doesn't sound like a successful test but they knew the RDX in its pure form burned far too fast to be useful as a firearm propellant so they had to "water down" its potency and deliberately erred on the side of caution. But now that they know to a certainty it's possible to print an RDX-based propellant charge that will fire when used in a firearm cartridge, they can go back and tinker with the formulation to get the conflagration properties that will make it sho-nuff usable in that role.

What I can't figure is why Red China would be interested in something like this in the first place. For one thing, now that they've let the cat out of the bag, it will inspire all of the big hitters in the western world to try to learn how to do the same, even if they don't know why.* So they've lost whatever hope they had for a monopoly on this technology by announcing it. And none of the gun pundits I've come across seem to have an inkling of why the Chinese might have thought there would be adequate return on this investment. But considering the Chinese penchant for playing the long game (make that very long game), IMHO it's a fair bet that they have an objective in mind that no one in the west yet has thought of.

*The US Air Force used to (and might still) have a top-secret museum at Nellis Air Force Base (outside Las Vegas). I got to visit it when I was there for a big inter-service exercise.

One of their "exhibits" was a Soviet-made MiG-23, a swing-wing supersonic fighter jet. Although it was Soviet-made, it was an export-only item, only ever intended to be used by the USSR's "monkey" states, so they called it a "monkey jet."

It was common for the Soviets to use designs and design elements stolen from the west, particularly in aircraft. The Tupolev TU-4 bomber of WWII was a rivet-perfect copy of the US's B-29. The US had consistently refused to give the Soviets any B-29s under Lend-Lease but a few of them that were engaged in the War in the Pacific had of necessity taken emergency refuge in the eastern USSR. The Soviets had not yet declared war on Japan so it coinsidered itself neutral in that conflict. As a neutral party it chose to abide by the pre-war Soviet–Japanese Neutrality Pact, which specified that the two countries agreed not to return any hardware it came into posession of from a country that was belligerent to the other. So the Soviets kept one of the B-29s and made faithful copies of it.

But back to the MiG-23. Yugoslavia used to have a communist strong man/dictator known as Marshall Tito. Although he was in the Soviet sphere of influence, if Yugoslavia got in a bind for cash he was know to sell the odd piece of military hardware the Soviets had lent him --- albeit with a Niemann Marcus mark-up -- to the west. Which is how the US Air Force came into possession of this particular MiG-23.

The MiG-23 started out with a number of elements copied from American aircraft, most notably the specific angles that the swing wings could be adjusted to were sourced from the F-111 Aardvark; 16° at the leading edge for take-off and landing and 72.5° for high-speed flight.

But in the early Mig-23 flight tests a problem emerged. The shock waves produced at transonic speeds interfered with the air flow into the engines and caused them to "flame out." They looked to other western aircraft for a zero-cost solution and some wizz kidski said, "Hey! The F-4 Phantom has a device mounted in front of the engine intake to deflect the shock wave so it doen't re-join the airframe until it's past the engine intakes....

So they simply copied the device (the US calls it a "ramp") from the F-4. The first image (below) is a MiG-23. The second image is an F-4 Phantom. And you can see how the device just forward of the engine intake might have been copied from the F-4 and modified only to suit the differences in the shapes of the aiframe.



But they didn't just copy the ramp. Notice in the bottom photo that there is a gap between the ramp and the F-4's airframe. There also is a similar gap aft of the intake between the fuselage and the engine nacelle.

This gap caused a potential problem because the US Navy employed the F-4 as a carrier-based fighter. Which obviously means it had to take off from and land on aircraft carriers.

Carriers have a system of "arresting" gear on the flight deck that can stop a landing aircraft without either letting it slide off into the ocean or stopping it so abruptly that the pilot's head gets popped off. The Vietnam-era aircraft carrier had a series of four steel cables they call "arresting wires" stretched across the flight deck with either end anchored to a shock absorber sort of device that would soften the impact when the tail hook on the landing aircraft snagged that cable.

Every time a pilot lands on a carrier his landing gets scored and each pilot's running scores are posted on a board in the flight room for all to see. And no matter how picture-perfect it might be, no landing is perfect unless you've snagged the "3-wire."

But what if you miss all four wires? In that case there's a net beyond the fourth wire that the jet will have a sort of controlled crash into.

And that's where the F-4's ramps proved a problem. If the top wire on the net ran right down the fuselage, it could get snagged behind the intake's ramp.

So how was that a problem? Look again at the second image, the one of the F-4 with the cockpit canopies open. If the top wire of the net slid all the way back to the wing root, it would be directly on top of the second (rearmost) canopy. That's the weapons system officer's (wizzo's) station. So the Wizzo would be trapped in the aircraft until somebody cut the cable at the top of the arresting net.

So they put a V-shaped hacksaw-like device at the wing root to serve as a wire cutter to preclude just such an eventuality. Same sort of device as many helicopters have on them in case of a "wire strike."


A Bell Jet Ranger with upper and lower WSPS (wire strike protective systems)

So whatever Soviet wizz kidski it was who grafted the F-4's ramp design onto the MiG-23 included the wire cutter as well.

But here's the deal. Look again at the top photo. The MiG-23 is a single seat aircraft. There is no "rear-seater", hence no canopy far enough aft to get held closed by the net.

Not only that, when the MiG-23 was designed, excluding submarines the Soviets still only had a "brown water" navy, for operating only in shallow "brown" waters near shore. And aircraft carriers are for projecting power over great distances, which is a blue water endeavor, so neither did the USSR have any true aircraft carriers.

So the MiG-23 was designed by a country with NO aircraft carriers and with absolutely ZERO attention given to operating it from a flat top.

So how come they copied the F-4's wire cutters? The only plausible explanation is that they couldn't figure out what they were for. But if the F-4 had them, they must be good for something, so we'd better use them to.

So you can bet the Americans (et Al) now will get fully invested in 3-d printing of gunpowder. Because even though we don't know what it's for, the Chinese wouldn't be doing this just for shits and giggles, so we can't afford to let their technology get ahead of hours.