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EndlessEmergency t1_itqwagn wrote

ITT: Non-engineers.

What this spec is saying is not "survive a cruise speed to full stop crash in 6.5 ms" but rather it can survive a series of decelerations and accelerations (bouncing from one direction to another is technically an acceleration) since its very very unlikely the plane (in parts) won't bounce and roll and shed all that kinetic energy over a wide area. It's a logical and reasonable goal.

Granted, crashing full speed into a vertical granite cliff might exceed those specs, but that's an edge case and we'll put it in the training docs that doing so is ill-advised.


somegridplayer t1_itqxqwl wrote

>but that's an edge case and we'll put it in the training docs that doing so is ill-advised.



tryingtodefendhim t1_itr5bmu wrote

TIL who the real edge lords are.


[deleted] t1_its3r6o wrote



Sharp_Building3453 t1_itty2e0 wrote

But if you came to a full stop in the jet stream then your air speed would then be negative, so the resulting math is the same.


LiamtheV t1_itt29xc wrote

Those bastards think Pi is 3, and g=10.

Engineers are all sick in the head, I tell you.


_Weyland_ t1_itr0bdt wrote

"In case you're falling make sure to not fall on the hardest rock"


obscureferences t1_itrr73k wrote

If engineers are so smart why don't they design the whole plane to these specs.

Thought so.


shingofan t1_its0sz2 wrote

Serious answer: the plane might survive, but its interior is going to look like the aftermath of that scene from Event Horizon.


SFXBTPD t1_itsc6p9 wrote

Typically interior stuff is rated for twice the Gs as the rest of the aircraft, so for civilian stuff that would be 18G ultimate.


crowley7234 t1_itt2ym0 wrote

I think he was referring to the sensitive meat bags enclosed in the plane.


TheSleepingNinja t1_ittdcsp wrote

Hey look at mister fancy pants over here flying Japanese Wagyu steaks


Akanan t1_itrlmmk wrote

Flight recorders are usually near the empennage which often remain intact after crashes, it's the area that suffers the least damage in most cases. Some FDR are even designed to be ejected before crash.


falconcountry t1_itsfn39 wrote

What good would it be as a data recorder if it's ejected before the crash


Akanan t1_itsfu0d wrote

It floats, the broken aircraft don't.

If the Malaysia airline crash 370 was equipped with one of these we would have it recovered.


Odeeum t1_itsnw0e wrote

I think they meant "what value is it if it doesn't record the actual crash data and is ejected too soon to gather any meaningful evidence?"

I could be wrong though but i think that was their intent.


Cerebro64 t1_ittb7u3 wrote

Investigators aren't interested in impact data. They are interested in the causes of the plane leaving normal flight. Yes, impact data might be useful but that's not what the recorder is for.


Odeeum t1_ittbnny wrote

So let's say the recorder is ejected a minute into the plane leaving normal flight...and the flight continues for another several minutes. Isn't that info highly relevant and sought after? Or are you talking seconds before impact that it's ejected? I'm curious how that mechanism works...certainly not a manual process by a terrified flight crew.


Cerebro64 t1_ittdmlc wrote

I'm not familiar with the actual ejection systems. But what you want a FDR to capture is attitude/altitude/speed etc and systems information. So when you have some kind of catastrophic incident you can identify the failures that led up to it. Were I designing that system it would be completely automated as no flight crew is going to even be considering FDR, nor should they. Also possible that it's structurally designed to separate on impact. For example, it stays in the plane until the moment of the crash, but the force of the crash compromises the installation of the box to separate it from the aircraft. Kind of like the intentional version of high speed car crashes with unbuckled passengers that get thrown clear during the crash sequence.


dressageishard t1_itsk7xq wrote

Still haven't found that plane.


flakAttack510 t1_ittknpx wrote

Not as a large piece but a lot of smaller pieces have washed up on various shores around the Indian Ocean.


guitarnoir t1_its78x8 wrote

> Some FDR are even designed to be ejected before crash.

I never heard this before--is a parachute system used post-ejection?


Akanan t1_its7l69 wrote

The aircraft I'm working on isn't an automatic system. It's manually by the Pilot.

It's a large foil that simply fly off and design to float and protect it's content if it lands on ground. It's not parachute but it's very light and large so it doesn't fall down like a rock.


guitarnoir t1_itsaefq wrote

> It's manually by the Pilot.

"Hey co-pilot, grab the 'Gonna Crash' checklist. What's it's say for Number 1?" "It says 'eject Flight Data Recorder' ". "Check".


Realistic-Astronaut7 t1_itse52i wrote

My first thought as well. They've certainly got a lot more to worry about/ do if they're ever in a situation where they might need that.


Pfheonix t1_itsd3p8 wrote

Flight Control loop:

>if(maneuver.WillCrash()) {


tminus7700 t1_itt7m63 wrote

I worked in the ordnance industry. We had to design warheads and electronics that could withstand 60,000g's for 20 milliseconds. These were used in "hard target warheads". Ones that had to penetrate a reinforced concrete bunker and still function properly. You can engineer things to with stand virtually anything. The physicist Lew Allen, in the 1950's experimented with getting steel balls to survive within the nuclear fire ball of an A- bomb blast.


doglaughington t1_itsm0b6 wrote

So, can engineers not build a better one? So many stories I read have been about the difficulty and inability to locate the boxes. Why haven't you and you engineer buds made a better one?


mtled t1_itssrej wrote

The industry is working on it, but it's difficult to get the industry up to speed quickly due to cost/infrastructure issues and, as with most things, pandemic delays.


EASA (European aircraft) have adopted Jan 1 2025 to mandate that all new built aircraft exceeding 27000kg have such a system installed. Offhand I don't know if, ever, existing older aircraft or smaller ones will need to install as it's a very expensive modification to integrate into an aircraft.

I'm also not aware of any current implementation timeline for FAA, Canadian or other country registered planes. I think India has adopted the ICAO mandate, which has the same 2025 date. I'm much too lazy to try to investigate this in-depth.


Henri_Dupont t1_itssq8z wrote

We're givin' it all she's got Cap'n! We canna break tha laws o' physics!


SpaceBoJangles t1_itswjcc wrote

Maybe a little more than I’ll-advised. I’d say that you should probably bold those words, make sure they understand how I’ll-advised.


EmbarrassedHelp t1_itt4c1x wrote

> Granted, crashing full speed into a vertical granite cliff might exceed those specs, but that's an edge case and we'll put it in the training docs that doing so is ill-advised.

We should setup a remote control passenger plane filled with crash test dummies to test this, to see if it does exceed the limits of the black box.


LesWhite t1_ittperb wrote

Was the Lufthansa crash over 600mph straight into a mountain? Or the China one that was nearly vertical?