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[deleted] t1_itqttw7 wrote

Reply to comment by wmantly in TIL that flight recorders must be able to withstand an acceleration of 3400 g for 6.5 milliseconds and that this is roughly equivalent to an impact velocity of 270 knots (310 mph; 500 km/h). by IchBinKoloss

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way2funni t1_itr9i0c wrote

>cruising at a cool 700mph

likely due to the jetstream effect throwing off the numbers.

you were probably in the polar jet which can reach speeds of up to 275 mph and runs west to east so if you were going TO EU, the effect of this tailwind could have easily boosted your speed 'across the ground' (which is what the SATNAV systems report) to 700 mph without any sound barrier shenanigans but 'airspeed' relative to the surrounding air was probably 500-550 which is standard cruise these days to conserve fuel.

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small_giant t1_itqz8s9 wrote

Now that I think about it, I took crap at 700 mph!

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guitarnoir t1_its7xjb wrote

"Did you just hear a giant fart?" "No, that was just a sonic boom--we're doing 700mph!"

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48for8 t1_itqujzz wrote

Sure that wasn't kilometers? Flights usually average 500 mph...either way still way above 310

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[deleted] t1_itqv0w2 wrote

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Poop_Tube t1_itr2052 wrote

Yes I believe it if it was with a tailwind. The air around them was moving 150-200mph so the plane relative to the air was below 500mph, not breaking any sound barrier.

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friedmators t1_itr0wcs wrote

Airspeed might be 150 less if you were with the jet stream.

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[deleted] t1_itr0t97 wrote

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way2funni t1_itrd1bi wrote

> The speed of sound is around 660mph

true but the jetstream going US to EU is doing a lot of that lifting to get a 700mph readout on the SATNAV system..

700 mph 'across the ground' can also and at the same time be 550mph 'airspeed' when you surf the polar vortex going west to east.

Even though the aircraft is moving at 700mph across the ground, there is no sonic boom or breaking of the sound barrier which requires the aircraft to break 660mph in airspeed.

The polar jetstream tailwind is no joke. It's how/why the typical NY to London flight time is approx 7 hours and London - NY is 8 hours +

They take advantage on it going to London and try to avoid it as much as possible when going back to NY.

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wmantly t1_itqtze0 wrote

That's what I'm saying, 310mph seems way too little.

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Brandon432 t1_itqvsci wrote

There is almost no chance the flight recorder comes to an instantaneous stop. The plane is going to crumble, so is the ground.

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