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Enroute Airbus A380 wake flips Challenger business jet upside down

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Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#351

Post by gingerbread-man »

antisthenes wrote: post #347
gingerbread-man wrote: post #216

Earlier quoted context omitted.

Speaking as someone who has actually done seatbelt enforcement, (I worked as a cop for a year after college before getting into software development,) catching people who aren't wearing their seatbelts is really, really hard. Each seatbelt ticket written probably takes ~30 minutes of time for the issuing officer.

Computer vision and machine learning to the rescue?

I think it would be a very hard problem. Take a look at some pictures of cars in traffic-- the seatbelt is extremely hard to see. If it were doable, it would probably take more optics engineers than ML scientists; glare and lack of contrast look like the biggest problems.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#352

Post by gingerbread-man »

antisthenes wrote: post #347
gingerbread-man wrote: post #216

Earlier quoted context omitted.

Speaking as someone who has actually done seatbelt enforcement, (I worked as a cop for a year after college before getting into software development,) catching people who aren't wearing their seatbelts is really, really hard. Each seatbelt ticket written probably takes ~30 minutes of time for the issuing officer.

Computer vision and machine learning to the rescue?

The truly cool application of technology to traffic enforcement is the speed camera lottery in Stockholm. I have very mixed feelings on automatic license plate readers: rules for what can and can't be done with the data they produce don't really exist, and that's a real problem.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#353

Post by gingerbread-man »

antisthenes wrote: post #347
gingerbread-man wrote: post #216

Earlier quoted context omitted.

Speaking as someone who has actually done seatbelt enforcement, (I worked as a cop for a year after college before getting into software development,) catching people who aren't wearing their seatbelts is really, really hard. Each seatbelt ticket written probably takes ~30 minutes of time for the issuing officer.

Computer vision and machine learning to the rescue?

The better way to make people wear their seatbelts would be to standardize a really annoying seatbelt alarm in every car. I have a Subaru Forrester, and if I unbuckle my belt for 10s in my driveway, it goes crazy.

Fun fact: At the police department, we actually had the seatbelt alarms for all of our cruisers disconnected. Being able to get quickly in and out without the seatbelts snagging on our gear was the priority at low speed. Most officers are trained to unbuckle and be ready to exit the vehicle before coming to a full stop (technically illegal.)

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#354

Post by jseip »

jseip wrote: post #2

The physics of this are insane. Then again, by my calculation the A380 displaces roughly 11 million cubic feet of air per second at the max landing weight.

EDIT: this is the net downward displacement of air sufficient to equal the A380 850,984lb max landing weight assuming a ballpark air density of ~0.075 lb/ft^3. The aircraft displaces much more air via its engines, fuselage and secondary effects, but the above number seems most relevant to the Challenger 604 ~1,000 feet beneath the aircraft :).

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#355

Post by dhimes »

jabl wrote: post #283
dhimes wrote: post #231

Earlier quoted context omitted.

Can you point to a source for those of us who want to know the right answer (like, sailors)?

Not the previous poster, but this was on HN a week ago: http://ljjensen.net/Maritimt/A%20Review%20of%20Modern%20Sail... https://news.ycombinator.com/item?id=13829625

Perfect. Thank you!

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#356

Post by gingerbread-man »

mikeash wrote: post #341
gingerbread-man wrote: post #285

Earlier quoted context omitted.

The challenge with measuring the safety of general aviation is that it is much more behavior-dependant. All of the US airlines use the same standards for deciding when to fly/ not fly for weather, have similar maintenance programs, training requirements, etc... When it comes to private air travel, it's all up to the pilot and the insurance company.

I imagine GA follows something like a Pareto distribution, with 10% of the pilots involved in 90% of the incidents. That 10% would get retrained or weeded out in the airlines, and the rest get much more consistency on all the rest of the stuff you mention. So yeah, there really isn't any one "the safety of general aviation." It's a huge spectrum. Another challenge is reporting. The FAA knows exactly how many flights…

From my limited experience working with them, the general aviation insurance industry seems ripe for startups. Data science is a huge deal in insurance, but the companies insuring Cessnas and Pipers don't seem to have fully caught on.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#357

Post by sctb »

peteretep wrote: post #130

> It's an incredible feeling, > lots of fun > Yes, it can be dangerous, > but it's a risk you can > manage yourself Try meth!

We detached this subthread from https://news.ycombinator.com/item?id=13892056 and marked it off-topic.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#358

Post by mannykannot »

ashark wrote: post #301
mannykannot wrote: post #208

Earlier quoted context omitted.

The common explanation of lift for laypersons contains a number of non-sequiturs and even falsehoods, but this is not one of them. Newton's laws applied to the situation play out in complicated fluid dynamics, and result in a pressure difference over the wing, with a reduction above. That difference, summed over the wing, is the lift (and also the source of the induced drag, I believe, but that is a step beyond.)

Fun fact: One of the weirdest things about heavier-than-air flight is that upon posting any explanation for it online, several people will tell you you're wrong. Each of them will also disagree with one another. All will have sources. [EDIT] This also happens with the Oberth Effect.

True, though I think it's more of a fact about the Internet than about flight.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#359

Post by mannykannot »

conistonwater wrote: post #321
chakalakasp wrote: post #202

Earlier quoted context omitted.

BTW the low pressure generating the lift thing is a myth. The lift is caused by the fact that the air is being deflected downward and good ol' Newton's Third Law.

Looking at https://www.grc.nasa.gov/www/k-12/airplane/wrong2.html it doesn't look like it's true that it's air being deflected that causes lift. There was a recent submission on HN explaining the theories of lift in sails: https://news.ycombinator.com/item?id=13829625 . AFAIU air is not dense enough to make this deflection account for the magnitude of lift forces actually observed.

The NASA article discusses a deliberately simplistic model that does not consider the deflection of airflow over the top of the wing, but it would be easy to overlook the caveat if you don't already know the answer. Further down the page there is a link to a correct Newtonian flow-turning model.

Re: Enroute Airbus A380 wake flips Challenger business jet upside down

#360

Post by wallace_f »

lutorm wrote: post #333
wallace_f wrote: post #191

Earlier quoted context omitted.

Can we talk about this in terms of actual statistics? How dangerous is flying without a seatbelt relative to say, driving without one?

I'm not saying the risk is particularly large, at least in a large aircraft. However, the inconvenience of buckling your seat belt is practically nil, so the value proposition is pretty clear to me.

The inconvenience of wearing a harness is subjective. Some people don't like it.
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