Avoid flames if possible, of course. But kerosene burning from a puddle is pretty sub optimal combustion - orange flame temps of maybe 1500 degrees C or so. Not good, but it's not a blowtorch.
But the structure should be able to deal with it. Apart from atmospheric heating, the bottom of the F9 is exposed to the exhaust of three engines for a minute or so during reentry. There is also direct exposure to the turbopump exhaust during launch and landing which simply exits straight out of the bottom of the vehicle - it's not directed to the S1 engine bells, or to the sides, or anything. If you have a close look behind the engine bells on ascent you can often see a lot of flame from the turbopump exhaust in there.
Have to wonder if they're doing something different with regards to engine shutdown - the last few landings have been a bit burny, earlier ones not so much.
"Reusable boosters are impractical. And landing on a barge? Not possible."
SpaceX begins to sucessfully reuse boosters.
"But these reusable boosters, they catch fire when they land!!"
WHEN THEY LAND - you know, that goal that, if you recall, was said to be impossible just a couple of years ago?
Or maybe they've just made landings boring enough that a bit of burning fuel on a section that is routinely covered in flames and hot gases during ascent and descent is news now.
That's right, because USB ports in cars and plain old cigarette lighter car chargers and solar chargers and small generators that are already running critical equipment and the like simply do not exist.
"Starting in 2018 more than 80 percent of all cars and trucks sold worldwide will be electric only or plug-in electric hybrids with a biodiesel option."
80 percent, you say.
"Despite their rapid growth, plug-in electric cars represented only 0.15% of the 1.4 billion motor vehicles on the world's roads, up from 0.1% in 2015." - Wikipedia - https://en.wikipedia.org/wiki/...
Escape velocity is the minimum velocity you need to completely escape Earth's pull. So if you you're on the Earth's surface, and you impart a velocity of 11km/s to an object, it will juuuuuuuust escape Earth's sphere of influence.
Similarly if you have an object in space that is juuuuuust within Earth's sphere of influence and it gets pulled in, it will have a velocity of at least 11km/s by the time it reaches the surface.
"At least" being the operative term there, because the object could already be heading towards Earth, in which case it will end up going at least 11km/s faster.
Even though they're NASA and have nothing to do with geophysical stuff, the sad fact is that the population expects them to come up with the answers. Bruce Willis' conversation in Armageddon sums it up:
Harry Stamper: What's your contingency plan? Truman: Contingency plan? Harry: Your backup plan. You gotta have some kind of backup plan, right? Truman: No, we don't have a back up plan, this is, uh... Harry: And this is the best that you-that the government, the US government could come up with? I mean, you're NASA for crying out loud, you put a man on the moon, you're geniuses! You're the guys that're thinking shit up! I'm sure you got a team of men sitting around somewhere right now just thinking shit up and somebody backing them up! You're telling me you don't have a backup plan, that these eight Boy Scouts right here [gestures to USAF pilots], that is the world's hope, that's what you're telling me? Truman: Yeah.
Those who fail to learn from history are doomed to repeat it. Possibly the most well-remembered example is Tulip Mania, which occurred in 1637.
Basically you attach the notion of immense value to some object which has little or no actual value, then sell limited shares in that object and let the hype train do the rest.
The grants aren't "free money". They're money to develop stuff that might not work out. Eg. the USAF grants to develop a new rocket engine.
You can't call them contracts, because the results aren't a fully delivered product with solid specs behind it. But there's R&D attached to them that is returned to whoever's handing out the money.
And NASA / USAF / DOD and government in general does this all the time - they basically gamble a little bit of their budgets and spread it about in the commercial/academic world to try and advance the state of the art, because the payoff is that those advances make things cheaper in the long run for them.
Anyone who qualifies for the subsidy can get it. It's just that there are very few companies in that space, which is why there's subsidies there in the first place, to help lower the barrier to entry.
I didn't skim the article, but did they mention that Telsa repaid a half-billion dollar loan from the Government 9 years early, in 2013?
I guess if the article does mention it, it'll grump about the fact that the government didn't get all the interest it was entitled to over the course of the loan......
Unlike other, more modern, news aggregation websites,/. never bothered to code in Unicode support when it started to become de rigueur. Now that the site has settled into the long slow decline to obscurity the Corporate Overlords say that there just isn't a business case for it, sorry.
Time to identify an object emerging from the undergrowth 20 metres away with a varying trajectory is minimal at 100km/hr. It's less than a second. Coupled with kangaroos typical behaviours - like running parallel to the road for a bit as you approach before jumping across in front of you - well, it's going to be tough to do with software.
Roo running alongside the road which is an immediate threat? Or person on a bike, which will maintain speed and position as you pass? Hard to figure that out in a couple of seconds unless you're doing full-on machine vision.
Roos are erratic creatures and can move very quickly. So one will be grazing 20 metres off the side of the road, become spooked by your headlights, bound onto the road in two or three hops, and hit your car.
It's about a second per hop for roos, so this takes place very quickly, well inside the illuminated area that your headlights project. Often they will appear from the vegetation on the side of the road and then be on the road in one hop, only 10 or so metres in front of you. It's why most cars in rural Australia are festooned with LED light bars and spotlights because the further and - most importantly - the wider you can see at night, the better.
Here are a few typical roo strikes to give you some idea of the problem -
Car says "Hey, put your hands on the wheel" every 5 minutes. Driver puts their hands on the wheel for 3 seconds without even looking at the road. Car is satisfied for another 5 minutes.
There isn't enough air in a fridge to cause significant condensation. A bar fridge has about 100 litres of air in it. 80% humidity air at 25 degrees has about 10 millilitres of moisture per cubic metre, so 1mL of moisture - in total - if you replace all the air in the fridge. If you removed the cold PC and left it on the bench for an hour just like you would with a cold can of coke, sure.
Apart from the lack of moisture available, operating electronics are warmer than their surrounds, so they would be the last place for moisture to condense upon.
If I was going to do this, I would use a chest freezer running at refrigerator temps so that every time you opened it, the cold air would stay in there with very little mixing with the outside air. But I wouldn't do this, because passive cooling with no fans is quite inefficient even with low temps, and while I haven't run the calcs, I would say a small heatsink + fan at room temp would transfer a lot more heat than that same heatsink sans-fan in the fridge simply because there is a greater mass of air forced over the heatsink by the fan.
About 15 years ago I was looking after an old Compaq ProLiant server that had a 6 disk SCSI raid array in some configuration I cn't recall.
Oh, a drive just failed with an "Exceeded power on hours" error? Well, that's ok, there's a hot spare in the array, no problem.
Next day, two other disks went offline, because they were all powered up at the same time when they were new, weren't they? And they were perfectly usable, it's just that the array controller noticed that their smart attributes had exceeded a threshold that equaled "failure", powered down the disk, and that was that.
I read the thread over on reddit and basically he turned up, was given his dev machine, and then given the instructions for creating the dev environment + db's & etc on his machine.
Then after a while he was like, "OK, let's see, step 17: Enter these commands to create your dev DB."
So he copied and pasted the commands from the document, like he'd been doing for the last 16 steps.
Unfortunately, the commands had the production db's connection in them. And they also had queries like, "drop database mainDB; create database mainDB; create table etc etc"
Jets can't recover from sudden depressurization via gaping hole in the cabin
Jets certainly can, because it's happened a few times in the past - most notably that Hawaii Airlines one where a stewardess got sucked out. Flight crew have "proper" emergency oxygen masks and are trained in their use. Passengers, if they're strapped in, well they tend to black out in about 30 seconds at 30,000+ feet, and you won't be at that altitude for long, because the pilot be descending at 10,000+ feet per minute, pronto.
Down there in the cargo bay however you have a lot of vital aircraft components going past - power and hydraulics, the avionics bay, centrally mounted fuel tanks, etc. If I had a choice between blowing out a door in flight (for example) or blowing a door-sized hole down below, I'd pick the hole in the passenger cabin every time.
WD-40 used to be great for fading ribbon cartridges. Squirt into the casing, give the ribbon a good wind through with a couple more squirts, good for ages.
Slashdot Mirror
14TB.
5120 applications.
So, 2700 megabytes per applicant.
Was this data stored as 5 minutes of uncompressed video of each page or something?
Wait, wait, I know, applications were stored as a scanned, multi-page TIFF, wasn't it?
Avoid flames if possible, of course. But kerosene burning from a puddle is pretty sub optimal combustion - orange flame temps of maybe 1500 degrees C or so. Not good, but it's not a blowtorch.
But the structure should be able to deal with it. Apart from atmospheric heating, the bottom of the F9 is exposed to the exhaust of three engines for a minute or so during reentry. There is also direct exposure to the turbopump exhaust during launch and landing which simply exits straight out of the bottom of the vehicle - it's not directed to the S1 engine bells, or to the sides, or anything. If you have a close look behind the engine bells on ascent you can often see a lot of flame from the turbopump exhaust in there.
Have to wonder if they're doing something different with regards to engine shutdown - the last few landings have been a bit burny, earlier ones not so much.
This does feel like a bit of goalpost shifting.
"Reusable boosters are impractical. And landing on a barge? Not possible."
SpaceX begins to sucessfully reuse boosters.
"But these reusable boosters, they catch fire when they land!!"
WHEN THEY LAND - you know, that goal that, if you recall, was said to be impossible just a couple of years ago?
Or maybe they've just made landings boring enough that a bit of burning fuel on a section that is routinely covered in flames and hot gases during ascent and descent is news now.
That's right, because USB ports in cars and plain old cigarette lighter car chargers and solar chargers and small generators that are already running critical equipment and the like simply do not exist.
"Starting in 2018 more than 80 percent of all cars and trucks sold worldwide will be electric only or plug-in electric hybrids with a biodiesel option."
80 percent, you say.
"Despite their rapid growth, plug-in electric cars represented only 0.15% of the 1.4 billion motor vehicles on the world's roads, up from 0.1% in 2015." - Wikipedia - https://en.wikipedia.org/wiki/...
Hmm.
Escape velocity is the minimum velocity you need to completely escape Earth's pull. So if you you're on the Earth's surface, and you impart a velocity of 11km/s to an object, it will juuuuuuuust escape Earth's sphere of influence.
Similarly if you have an object in space that is juuuuuust within Earth's sphere of influence and it gets pulled in, it will have a velocity of at least 11km/s by the time it reaches the surface.
"At least" being the operative term there, because the object could already be heading towards Earth, in which case it will end up going at least 11km/s faster.
Even though they're NASA and have nothing to do with geophysical stuff, the sad fact is that the population expects them to come up with the answers. Bruce Willis' conversation in Armageddon sums it up:
Harry Stamper: What's your contingency plan?
Truman: Contingency plan?
Harry: Your backup plan. You gotta have some kind of backup plan, right?
Truman: No, we don't have a back up plan, this is, uh...
Harry: And this is the best that you-that the government, the US government could come up with? I mean, you're NASA for crying out loud, you put a man on the moon, you're geniuses! You're the guys that're thinking shit up! I'm sure you got a team of men sitting around somewhere right now just thinking shit up and somebody backing them up! You're telling me you don't have a backup plan, that these eight Boy Scouts right here [gestures to USAF pilots], that is the world's hope, that's what you're telling me?
Truman: Yeah.
Those who fail to learn from history are doomed to repeat it. Possibly the most well-remembered example is Tulip Mania, which occurred in 1637.
Basically you attach the notion of immense value to some object which has little or no actual value, then sell limited shares in that object and let the hype train do the rest.
The other side of this, as a purchaser, is :
"Why would I spend my bitcoins now, when they are very likely to be worth more tomorrow?"
The first proper bitcoin purchase - where 2 pizzas was purchased for 10,000 bitcoins - comes to mind here.
Volume equalisation between tracks and albums mainly.
"The shit only comes up to my knees, so it's not that bad I guess."
The grants aren't "free money". They're money to develop stuff that might not work out. Eg. the USAF grants to develop a new rocket engine.
You can't call them contracts, because the results aren't a fully delivered product with solid specs behind it. But there's R&D attached to them that is returned to whoever's handing out the money.
And NASA / USAF / DOD and government in general does this all the time - they basically gamble a little bit of their budgets and spread it about in the commercial/academic world to try and advance the state of the art, because the payoff is that those advances make things cheaper in the long run for them.
Anyone who qualifies for the subsidy can get it. It's just that there are very few companies in that space, which is why there's subsidies there in the first place, to help lower the barrier to entry.
I didn't skim the article, but did they mention that Telsa repaid a half-billion dollar loan from the Government 9 years early, in 2013?
http://money.cnn.com/2013/05/2...
I guess if the article does mention it, it'll grump about the fact that the government didn't get all the interest it was entitled to over the course of the loan......
Don't be. Slashdot and Unicode just don't mix.
Unlike other, more modern, news aggregation websites, /. never bothered to code in Unicode support when it started to become de rigueur. Now that the site has settled into the long slow decline to obscurity the Corporate Overlords say that there just isn't a business case for it, sorry.
Can someone, PLEASE, take MR President's twitter account away from him? Shit's embarrasing, and I don't even live in the US.
Sensor range isn't headlight range.
Time to identify an object emerging from the undergrowth 20 metres away with a varying trajectory is minimal at 100km/hr. It's less than a second. Coupled with kangaroos typical behaviours - like running parallel to the road for a bit as you approach before jumping across in front of you - well, it's going to be tough to do with software.
Roo running alongside the road which is an immediate threat? Or person on a bike, which will maintain speed and position as you pass? Hard to figure that out in a couple of seconds unless you're doing full-on machine vision.
It's not about depth perception.
Roos are erratic creatures and can move very quickly. So one will be grazing 20 metres off the side of the road, become spooked by your headlights, bound onto the road in two or three hops, and hit your car.
It's about a second per hop for roos, so this takes place very quickly, well inside the illuminated area that your headlights project. Often they will appear from the vegetation on the side of the road and then be on the road in one hop, only 10 or so metres in front of you. It's why most cars in rural Australia are festooned with LED light bars and spotlights because the further and - most importantly - the wider you can see at night, the better.
Here are a few typical roo strikes to give you some idea of the problem -
https://www.youtube.com/watch?...
https://www.youtube.com/watch?...
https://www.youtube.com/watch?... - This one in particular.
It was Yakkety Sax, as is tradition.
It is most likely not 37.5 minutes in one go. eg:
Car says "Hey, put your hands on the wheel" every 5 minutes.
Driver puts their hands on the wheel for 3 seconds without even looking at the road.
Car is satisfied for another 5 minutes.
There isn't enough air in a fridge to cause significant condensation. A bar fridge has about 100 litres of air in it. 80% humidity air at 25 degrees has about 10 millilitres of moisture per cubic metre, so 1mL of moisture - in total - if you replace all the air in the fridge. If you removed the cold PC and left it on the bench for an hour just like you would with a cold can of coke, sure.
Apart from the lack of moisture available, operating electronics are warmer than their surrounds, so they would be the last place for moisture to condense upon.
If I was going to do this, I would use a chest freezer running at refrigerator temps so that every time you opened it, the cold air would stay in there with very little mixing with the outside air. But I wouldn't do this, because passive cooling with no fans is quite inefficient even with low temps, and while I haven't run the calcs, I would say a small heatsink + fan at room temp would transfer a lot more heat than that same heatsink sans-fan in the fridge simply because there is a greater mass of air forced over the heatsink by the fan.
About 15 years ago I was looking after an old Compaq ProLiant server that had a 6 disk SCSI raid array in some configuration I cn't recall.
Oh, a drive just failed with an "Exceeded power on hours" error? Well, that's ok, there's a hot spare in the array, no problem.
Next day, two other disks went offline, because they were all powered up at the same time when they were new, weren't they? And they were perfectly usable, it's just that the array controller noticed that their smart attributes had exceeded a threshold that equaled "failure", powered down the disk, and that was that.
It wasn't a very pleasant week after that.
I read the thread over on reddit and basically he turned up, was given his dev machine, and then given the instructions for creating the dev environment + db's & etc on his machine.
Then after a while he was like, "OK, let's see, step 17: Enter these commands to create your dev DB."
So he copied and pasted the commands from the document, like he'd been doing for the last 16 steps.
Unfortunately, the commands had the production db's connection in them. And they also had queries like, "drop database mainDB; create database mainDB; create table etc etc"
Whoopsie!
Jets can't recover from sudden depressurization via gaping hole in the cabin
Jets certainly can, because it's happened a few times in the past - most notably that Hawaii Airlines one where a stewardess got sucked out. Flight crew have "proper" emergency oxygen masks and are trained in their use. Passengers, if they're strapped in, well they tend to black out in about 30 seconds at 30,000+ feet, and you won't be at that altitude for long, because the pilot be descending at 10,000+ feet per minute, pronto.
Down there in the cargo bay however you have a lot of vital aircraft components going past - power and hydraulics, the avionics bay, centrally mounted fuel tanks, etc. If I had a choice between blowing out a door in flight (for example) or blowing a door-sized hole down below, I'd pick the hole in the passenger cabin every time.
"Two things only the people anxiously desire - Bread and Circuses."
WD-40 used to be great for fading ribbon cartridges. Squirt into the casing, give the ribbon a good wind through with a couple more squirts, good for ages.