If a google interview inspired nutcase did fill a 747 with golfballs, what would happen to the plane? Would the overloading break anything? Would the aviation authorities demand expensive inspections before it returned to service? Or would it just be condemned?
Pardon me, but what? (link, please, if possible)
The 747-8 (freighter type) has a payload capacity of about 300,000 lbs, or 140,000 kgs, so I think it would be hard to overload it or break anything. A passenger version has a lesser payload, but still large enough to carry a full plane of ping-pong balls.
I presume that you would simply be dumping the balls in the plane until it was packed…as long as all doors/hatches to the avionics/equipment/engines/cockpit/etc. were secure, I don’t see why it would cause the plane to be taken out of service.
I will. of course, bow to those dopers who are wiser than I.
There’s a bit of difference between golf balls and ping pong balls.
Short version:
Per wiki the 747-8F freighter has a cargo capacity (including the main deck and the belly spaces) of 30,177 cu ft & a max payload of 295,800 lbs Boeing 747-8 - Wikipedia. So that’s 9.8 lbs / cu ft. So if you fill the aircraft to the brim with any bulk cargo weighing more than about 10#/cu ft, you’ll overload it.
A golf ball has volume 2.48 cu inches and weighs 1.6 oz Golf ball - Wikipedia. So the density of golf ball material in bulk is roughly 69 lbs/cu ft. But spherical balls don’t pack that tightly. For round numbers random packing density of relatively small spheres in relatively large containers is 64% Random close pack - Wikipedia. So a large container poured full of golf balls will weigh roughly 45#/cu ft. If you carefully stacked the individual balls to ensure they packed as densly as possible, you’d achieve 74% packing density or 51 lbs / cu ft. Which would be even heavier.
Either packing is a density about 10x heavier than the airplane can stand. You’ll comprehensively break the airplane long before it’s full of golf balls. The gear will collapse, or break through the supporting structure, or the wings will break off at the roots. It’ll be spectacular and expensive no matter how exactly it plays out.
Long version:
There is a published maximum weight to taxi. If we move the aircraft even an inch while above that weight an inspection is required. On very heavily loaded flights this becomes an issue that’s watched carefully down to the pound. Everything is reconciled *before *we push back from the gate.
There’s another weight limit which is the total weight excluding fuel. So that’s basically the aircraft itself plus the payload. Typically the limits are such that you can’t fill both the fuel tanks and the payload simultaneously to max. So for our experiment we’d get more golf balls or whatever in there before breaking a limit by leaving the fuel tanks mostly empty. That’s the limit I used in my short version calc above.
As pilots we’re not told of a maximum static total load. It would be someplace north of the maximum taxi load. I’ve never heard of a loading screw-up big enough to trip that limit, but it’s certainly possible.
Tripping any limit will trigger an inspection. The bigger the exceedance the bigger the inspection. The manufacturer computes and publishes the gradation of exceedances and corresponding procedures. If you overloaded the aircraft farther than they ever anticipated then you’d be looking at grounding the aircraft until you could pay them to figure out how to inspect for damage you may have caused. And if you found any damage you’d be paying them to engineer up a procedure to repair it.
It doesn’t take too much custom engineering like that to total out an airplane, especially an older one. As a sorta-similar example, Delta had an elderly 747 fly through a hail storm a month or so ago. Oops. They’re probably going to scrap the airplane. There’s no mystery in what to repair or how to repair it. It’s simply the case that the damage is extensive enough and the down time is long enough that it’s cheaper to scrap it than fix it. See http://www.bizjournals.com/twincities/news/2015/07/10/delta-hail-nwa-n664us-boeing-747-boneyard-pinal.html
Using some highly accurate numbers that I retrieved from google (ahem…) it turns out that golf balls weigh a maximum of 1.62 ounces, and, believe it or not, people have already calculated how many golf balls will fit on a 747 (the google question that the OP references), which is roughly 23 million. If I did my math right, and it’s early here so no guarantees, that means the 23 million golf balls will weigh about 2.3 million pounds.
That should overload the plane by a bit.
One thing to keep in mind is that the maximum payload weight is based on how much weight the plane can carry and still get off of the ground. I imagine that the maximum weight that can be loaded into the plane without damaging it is significantly higher. I’m guessing that 2.3 million pounds is far enough over the weight limit that it would cause some damage, though.
I have no idea what the airline company would do with the plane at that point, though.
There are stories about people applying for a job at Google and being asked interview questions like “Approximately how many golf balls could you fit inside a 747?” These questions are supposedly intended to see if the applicant can take an improbably situation and apply rational analysis to it.
Late edit: Change “10x” in the 3rd paragraph to “5x”. The rest of the content stands as is.
What annoys me about this type of question is that they don’t let you have access to, uh, google. Or even access to the numbers you need - sphere packing density, volume of a 747, mass of a golf ball, volume of a golf ball. You’re supposed to just guess. That’s lame and prevents you from getting anywhere close to the correct answer.
It’s an interview question. The point isn’t to come up with a correct answer, the point is to demonstrate how you would think through this kind of problem. They’re looking to see if you’d just pull a WAG out of thin air, or try to think through and come up with an estimate that comes close, or ask the interviewer to clarify the question, etc.
'zactly. It’s a test of your algorithm-creating skills, not your arithmetic skills.
And it’s not really even testing your estimating skills, within reason. e.g. …
If you assumed a 747 interior was 200 feet long when the actual number is 150 feet, your volume would be ~33% too high. But your approach would still be sound (or not) and the Q&A would still provide insight into your suitability.
Now if you assumed the 747 interior was 10 feet or 1000 feet long that would probably get you labeled too clueless to hire as janitor. Estimates don’t have to be perfect, just plausible.
Or at least that’s true if the interviewer is using the question validly. As always with interviews, there’s no assurance the bozo asking the questions is even remotely qualified to do so.
I used a rough rule of thumb in my head for this, I figured 500 humans at 200# each X10 to fill empty spaces and figured the golf balls at 1.6 oz each. I came up with about 10,000,000 balls. Using the exact figures listed above it comes out to about 12,000,000. I surprised myself it came out so close.
Even to attempt this would take a lot of balls.
One thing to be aware of… if you deviate too far left or right from your flight plan you have to take a one stroke penalty and return to the airport and take off again.
If you can’t get anywhere close just by guessing, then you’re not the kind of person Google is looking for. With good analytical reasoning skills, you can actually get pretty close.
You can also be wildly off. And google themselves has concluded that these kinds of interview questions are completely worthless.
DOH!!! :smack::smack::smack:
Nevermind.
The problem is when the plane rotated for take-off and all the balls rolled aft. Remember that video of the plane that crashed after take-off when the load broke free?
I hate stupid interview questions.
At the very least “four!”.
Treadmill, people, treadmill.
Mighten’t they cannibalize any reusable parts from it?