[jamieplex]

Approximately 8' diameter (other commenters pointed out a more reasonable size) solid steel ring gear (riveted together from 4 parts). Doesn't look anything like a "separation ring", and certainly isn't large enough. Plus it is solid steel. I am kinda doubting the whole story at this point. No way it is from a rocket (too heavy, too low-tech, no ring gears in rocketry), and doubtful from any commercial aircraft (again, too low-tech and too heavy).

[buildsjets]

For reference, here is a ring which is believed to have come from China's Long March BuNo Y77. Note the similar scale, and similar discoloration. https://spacenews.com/india-examining-crashed-space-debris-s...

I design and build all sorts of hardware relating to air-breathing (jet) propulsion, including gears. I agree with mkl. Those are not gear teeth. They have flat flanks, and no involute profile. No one makes gears with a gigantic U shaped root. They appear to me to most likely be clearance slots, to go around protruding bolt heads on a mating part. I have designed similar counterbore features myself.

What makes you claim that this part is steel? The article does not say that. Is that a fact, or are you guessing?

[mkl]

The appearance of rust on the surface of the article's main photo suggests steel. I guess heat from reentry may lead to that appearance on other materials?

[mkl]

An earlier article [1] linked in this one says about 1.2m radius, so ~2.4m or ~8ft diameter. At 48 seconds in the video there's a man standing next to the propped up side and it comes up to his chest, so that seems believable (the other side is down a slope).

It seems surprising it weighs 500kg though, as it's held up by a thin iron/steel pipe/bar. If it's solid mild steel at 7850kg/m^3, with an outer radius of 1.2m and inner radius of 1.05m, and a thickness of 4cm, that would be (π*1.2^2 - π*1.05^2)*.04*7850 ≈ 333kg. If the inner radius is 1.0m and thickness is 5cm, that would be ~543kg, so maybe it is that heavy.

Edit: The tooth profile looks strange for a gear. There's a clear but potato-resolution view at 36s in the video. The teeth have flat tops with sharp corners, the sides are pretty vertical, and the gaps have very rounded bottoms.

[1] https://nation.africa/kenya/counties/makueni/mystery-object-...

[russdill]

Lots of rocket components look like gears. The outside skin of the rocket often had internal vertical stringers and so components need cutouts that end up looking a bit like gears

[jamieplex]

true, but I guess I have never heard of an 8' diameter rocket before...

[Stevvo]

You're just making stuff up? Photos show diameter is larger than human height, maybe 8'. Only indication it's "solid steel" is you said it is.

[jamieplex]

sorry, I estimated from the grainy footage. Relax, man...

[buildbot]

The rust does stand out as kind odd, not many aerospace materials rust???

How fast would you have to spin a gear ring to say, launch it on a ballistic trajectory and have it go supersonic? Maybe a factory somewhere had a _really_ catastrophic accident?

[petee]

Things tend to burn up in re-entry if they're not designed for it, and this wasn't designed for it. Many metals oxidize when super heated

[Danmctree]

There have been a bunch of very powerful non-nuclear explosions. Perhaps a part of an exploding ship such as in the halifax explosion or the Princess Irene?

[jamieplex]

Maybe that was the "rumbling" they all heard! lol

[Footkerchief]

2.5 m (8 ft 2 in) in diameter:

https://en.m.wikipedia.org/wiki/M-V

[ivewonyoung]

Maybe it was something like this?

https://old.reddit.com/r/nextfuckinglevel/comments/1bmpxaq/t...

The diameter seems to match.

[philipwhiuk]

I thought it might be an jet-engine cowl, but I don't know enough about planes.

[jamieplex]

Cowlings are generally thin aluminum or composite materials, never steel. Cowlings are considered "fairings", generally to smooth the air-stream in and around the engine.

[buildsjets]

Do you have a theory on where the rest of the airplane went?

[petee]

The rivets and joints are very much aerospace style.

[jamieplex]

ok....

[rectang]

Could be from a concrete mixer. (Credit: rando YouTube comment.)

[hermitcrab]

From that concrete mixer the Mythbuster's blew up? It took a while to come down...

[throwaway519]

Bearings are single cast.