[eh_why_not]

https://en.wikipedia.org/wiki/Kosmos_482

> Its landing module, which weighs 495 kilograms (1,091 lb), is highly likely to reach the surface of Earth in one piece as it was designed to withstand 300 G's of acceleration and 100 atmospheres of pressure.

Awesome! I don't know how you can design for 300 G's of acceleration!

[WJW]

Overbuild everything. For things that might be fragile-ish like surface mounted electronics, cast the whole thing in resin. As a sibling poster has mentioned, we shoot things out of artillery tubes these days that have way harsher accelerations than 300g.

[MarkMarine]

300g is nuts. Electronics in a shell is one thing, this is a landing craft. In a prior life my designs had to survive 12g aerial drop loads and we had to make things pretty robust.

[consumer451]

It also blew my mind that a human being, John Stapp, survived >40g acceleration and 26g deceleration, in a rocket sled. I believe it was the deceleration that hurt him the most.

[numpad0]

Gun scopes are minimum 500G rated. Apparently that's the ballpark for recoils(the reaction force from the barrel becoming a rocket engine, and/or the bolt/carrier bottoming out)

[os2warpman]

There are electronics and gyroscopes designed for >9,000 G loads, in guided artillery shells.

Aerospace is awesome.

[nandomrumber]

88.2 m/s^2

For well under a second though, typically artillery muzzle velocity is, what, two to three thousand feet a second?

Still, it’s wild that guidance electronics and control mechanisms can survive that sort of acceleration.

[af78]

According to https://en.wikipedia.org/wiki/M777_howitzer (typical howitzer):

- barrel length (x): 5.08 meters

- muzzle velocity (v): 827 m/s

Assuming a constant acceleration γ, x = γ * t² / 2 and v = γ * t

Hence:

- t = 2 * x / v = 12.29 ms

- γ = v / t = 67316 m / s² = 7000 G

A bit lower than 9000 G, but in the same ballpark.

Certain rounds, like Excalibur (https://en.wikipedia.org/wiki/M982_Excalibur) or BONUS (https://en.wikipedia.org/wiki/Bofors/Nexter_Bonus), are sophisticated and are able to cope with such accelerations.

[Baeocystin]

That vacuum tubes(!) were part of that package, and were able to be that robust, still floors me every time I think about it.

[MathMonkeyMan]

> 88.2 m/s^2

Isn't that more like 9g?

[nandomrumber]

Yes, thanks, I meant to write 88.2 kilometres / second squared.

[casylum]

If anyone wants to try and see it the orbit is listed.

https://www.n2yo.com/passes/?s=6073

[dgrin91]

Nitpicking, but wouldn't it be 300 Gs of deceleration? I know the math is basically the same, but technically the words a mean different things

[crazydoggers]

Acceleration is a vector. So if you apply the “deceleration” long enough you’ll eventually be accelerating in the opposite direction. Without a frame of reference it’s all the same. Even with a frame of reference you’re still accelerating just that it’s in he opposite direction of the current velocity.

[Eduard]

I fly through trams in completely different directions depending on whether it accelerates or decelerates. So for sure a system's design must consider more than just the magnitude of acceleration.

[agurk]

When you go around a tight corner and are thrown to one side, what term would you use for the tram's change in motion then?

Deceleration is a useful but non-technical term, like vegetable. A tomato is a fruit which is a tightly defined concept, but it is in this loose category of things called vegetables. It's still useful to be able to call it a vegetable.

From a physics perspective all changes in motion (direction and magnitude) are acceleration, and it's correct to say the designers had to consider acceleration in most (all?) directions when designing the tram. This is including gravity's, as they tend to give you seats to sit on, rather than velcro panels and straps like on space ships.

It is useful to say to your friend in the pub that you got thrown out of your seat due to the tram's heavy deceleration, rather than give a precise vector.

[crazydoggers]

Without looking out the window how would you tell the difference between acceleration or deceleration? You can’t.

And if you say “well one way I fly to the back of the tram and the other the front” You’re arbitrarily associating “front” with decelerate and “back” with accelerate.

300gs is 300gs regardless of the direction vector of the component.

> So for sure a system's design must consider more than just the magnitude of acceleration.

What else would you need to consider? Acceleration up? Down? Left? 20%x,30%y,40%z? There’s an infinite number of directions.

[anyfoo]

Well to be fair, the person you reply to has a point. There’s a continuous range of directions, but even though I’m no spaceship engineer, I suspect they’re probably engineered to withstand acceleration better in some directions than others, given that pretty much only their thrust method, as well as gravity at source and destination, will actually be able to apply any acceleration.

[saagarjha]

You can tell because they typically accelerate faster than they decelerate.

[ryandrake]

“The enemy's gate is down.”

[FredPret]

They tend to do this with spacecraft by turning the whole craft so acceleration always comes through the floor

[amoshebb]

I think this is a case where “technically” the words mean the same thing but “generally” they mean different things.

[Rover222]

This is wrong when talking about the physics of something. Deceleration is acceleration. Acceleration is just a change in velocity.

[anyfoo]

Acceleration, deceleration, point is: Something is going to apply 300 gs in a certain direction to design for.

It's not like you can tell whether you're going slow or fast, in one direction, the other direction, or even just standing still, if you close your eyes.

[stickfigure]

Sure you can. You just need a luminiferous aether detector.

[anyfoo]

Of course, my bad. Otherwise the speed of light would have to be constant in any reference frame, and that would just be ridiculous.

[drob518]

It’s just a minus sign.

[jbnorth]

What is deceleration but acceleration in the opposite direction? /s

[JohnKemeny]

There's no need for the "/s" on the end, there. Deceleration, and especially in this case with a natural frame of reference, deceleration is negative acceleration.

[rightbyte]

More stringently, deceleration is decreasing the magnitude of the velocity vector, I would say.

If acceleration can be negative, so can speed. A negative speed with negative acceleration would not imply deceleration?

[DiogenesKynikos]

The magnitude of the velocity vector is dependent on the frame of reference.

If you measure the same object's velocity from a spaceship traveling through the solar system, you'll get a different answer from what we measure from Earth.

That's why physics doesn't distinguish between acceleration and deceleration. What looks like acceleration in one frame looks like deceleration in a different frame.

[mongol]

Speed is not a vector, it is a scalar. You are thinking of velocity.

[exabrial]

Flip your phone upside brah