Yeah. Dawn's ion engines (linked to in TFS) have a very high ISP (3100s), but an equally low thrust (90 mN). As a comparison, the F-1 engines on the Saturn V Stage I-C had pretty low ISP (about 250s), but a massive 34 MN of thrust.
Basically you can have high ISP (electrical) or high thrust (chemical), but not both.
Unless you go VASIMR, of course, and we're not quite there yet.
From wikipedia: "Presently there are about 500 active volcanoes in the world – the majority following along the Pacific 'Ring of Fire' – and around 50 of these erupt each year.[6] The United States is home to 50 active volcanoes.[7] There are more than 1,500 potentially active volcanoes.[8] An estimated 500 million people live near active volcanoes.[9]"
As for scaling up the device, one need only look here to see its tremendous potential.
"Tremendous potential"? It needs 40-70 kV to lift its massive weight of 6 grams - what does its power source weigh?
And given the knowledge that capacitors with solid dielectrics work in a vacuum we can see that with higher K dielectrics, more advanced materials, and an on board power source such as a hybrid engine, such technology could be put to use to create a vehicle suitable for air, land, sea, or space travel.
Given enough handwavium, anything's possible. I'll get on board with ionocrafts when they can actually lift themselves AND their powersource. Currently, that's not even theoretically possible without handwaving.
Yes, lifters are fine. As a science fair project for school kids. For propulsion on a plane/space vehicle? Not so much. They produce about a gram of lift per watt. So far, payloads as massive as 60 grams have been lifted. Next stop, the moon? Also, the voltages needed for them to function are extremely high, 20-50 kV for the science-fair models. That kind of apparatus weighs orders of magnitude more than the lift generated. And, to add insult to injury, they produce ozone when in use.
Not a very green (or realistic) alternative to rockets.
Now it is clear that anyone working with rocket fuels is outstandingly mad. I don't mean garden-variety crazy or a merely raving lunatic. I mean a record-shattering exponent of far-out insanity.
There are, after all, some chemicals that explode shatteringly, some that flame ravenously, some that corrode hellishly, some that poison sneakily, and some that stink stenchily. As far as I know, though, only liquid rocket fuels have all these delightful properties combined into one delectable whole.
Also, I'd like to also state my thanks to imbaczek for posting the link, 40 pages in and it's a page-turner:)
Use the link in the summary to download the draft of the book, chapter 2 should give you enough of an overview to know at least some things you can do with PDL.
How do you keep a hole 13,100 ft deep melted when the average temperature in summer is -30C (-22F), and in winter -65C (-85F)? The warmest it ever gets is about -12C (10F) - that's a record by the way, the warmest ever measured at Vostok station.
It's not exactly a resort, you know:
The warmest recorded temperature at Vostok is -12.2 C (10.0 F), which occurred on 11 January 2002.[10] The coldest month was August 1987 with a mean temperature of -75.4 C (-103.7 F) and the warmest month was December 1989 with mean of -28 C (-18 F).[9] In addition to the extremely cold temperatures, other factors make Vostok one of the most difficult places on Earth for human habitation: * An almost complete lack of moisture in the air. * An average windspeed of 5 m/s (18 km/h) (11 mph), sometimes rising to as high as 27 m/s (97 km/h)(60 mph). * An acute lack of oxygen because of its high altitude at 3,488 meters (11,444 ft). * A higher ionization of the air. * A polar night that lasts approximately 130 days, from mid April to late August,[13] including 80 continuous days of civil polar night (i.e. too dark to read, during which the Sun is over 6 degrees below the horizon.)
Been digging since 1974. That's 344 feet a year, or a foot per day. Hell, *I* could have dug quicker than that!
Or maybe they just had lots of problems, costs, setbacks, etc. associated with a 13,000 foot-long drill through a substance that nobody has ever drilled 13,000 down through?
It's also in the middle of the Antarctic, just about, and almost 900 miles from the Scott-Amundsen base at the South Pole. It's where the coldest temperature on earth has been measured, a whopping -128F (-89C). I'd love to see anyone dig a foot *that* day!:)
Indeed it was; by the CIA no less, using phoney companies.
The USSR was the world's largest producer of titanium (and Russia still is), but that doesn't mean they could afford using it or indeed that they had the skill to do so in their aerospace industry. Specifically for the MiG-25, they couldn't solve the problem of cracks in thin welded titanium so they went with the heavier nickel-alloy steel instead.
Also, another reason they went with nickel-alloy steel might be that most of the titanium produced in the USSR at the time the MiG-25 was constructed and built went to the navy and their Alfa class submarines.
The A-12 was the precursor to the SR-71; the YF-12 was the prototype that became the SR-71. In essence, all three are the same aircraft. The XB-70 was a prototype; there only ever were two of them. It broke Mach 3 on ten occasions. X2 and X15, as you say, are experimental rocket planes, not production aircraft; they also had severely limited flight times. The MiG-25/MiG-31 could theoretically sprint to Mach 3.2, but was never built to exceed Mach 2.8 - it couldn't handle the temperatures involved.
No, there ever really was one production aircraft that regularly (11,000+ hours at Mach 3+ according to official records) could do Mach 3+; the SR-71. While its true top speed is still classified, it was nowhere near the figures the GP believes; according to pilots accounts the plane couldn't do much more than Mach 3.5.
The official declassified top speed was Mach 3.2+. If you read pilot's accounts, they regularly pushed the plane to Mach 3.5 when under missile threat. I'm sure they would have pushed it further if it could go further.
XB-70 was a prototype, they built two of them in total. They broke Mach 3 a grand total of ten times. MiG-25, as I said, doesn't count. It could only theoretically handle Mach 3. X-15 is a rocket, not a plane. It needed to be air-launched from a B-52.
Face it, there were never "lots of planes" that could do Mach 3+. There really ever was the SR-71.
As for your "theories" about the SR-71's top speed I can only say that you're wrong. The flight manual of the SR-71 has been declassified for quite a while now; I suggest you go read it: http://www.sr-71.org/blackbird/manual/.
Finally, a word or two on the MiG-25 and friction heating. The MiG-25 was built out of nickel-steel alloy because the soviets couldn't afford/couldn't work well with titanium. As you observed yourself, nickel alloys were also used on the X-15 to protect it from friction heat. So your claim that the MiG-25 was "capable of 3.2 without anything unusual" is bogus. It was built from 80% nickel steel alloy, if they had been able to afford it or work with it, it would have been built out of titanium like the SR-71.
Around Mach 3, the increased heating from the shock cone compression, plus the heating from the compressor fans, was enough to get the core air to high temperatures, and little fuel could be added in the combustion chamber without melting the turbine blades. This meant the whole compressor-combustor-turbine set-up in the core of the engine provided less power, and the Blackbird flew predominantly on air bypassed straight to the afterburners, forming a large ramjet effect. The maximum speed was limited by the specific maximum temperature for the compressor inlet of 800 F (427 C).
The SR-71 had enough problems coping with the temperatures generated at Mach 3, it was never designed for anything much above Mach 3.5.
lots of planes can do Mach 3
Really? Name three. MiG-25/31 don't count since they had a more than 50% chance of burning out both engines if they went over Mach 2.8 or so.
And, I talked to a retired traffic controller who once saw a '71 light up a civilian transponder so traffic could be vectored around it (it had an emergency apparently), they clocked it around 4000mph.
I'm glad that traffic controller is retired, because if he clocked an SR-71 at 4000mph, he was drinking on the job.
* The worldwide production of uranium in 2009 amounted to 50,572 tonnes. * The worldwide production of coal is estimated to more than 7,000 million tonnes. * Uranium is generally mined by in-situ leaching, which does not entail going underground at all. * Coal is still mined by people going underground in many places. * There's 4,000 cases of black lung from coal mining every year in the US alone (10,000+ in China). * The major health hazard in uranium mining was radon gas inhalation. These days safety regulations and ventilation is such that the workers aren't exposed to more radon than in some homes.
Either way you try to look at these numbers, mining coal is more dangerous than mining uranium.
It's because most of us are bored to tears with "AMAGADNUCULARISBAD!".
If you actually look at statistics - you know, data; hard cold facts and figures - nuclear is the safest way of producing electricity we've come up with. Coal/gas/oil are more polluting, solar/tidal/wind aren't base-load capable, and geo/hydro has its own set of problems, not least of which is killing a lot of people when dams go bust.
And all of them kill more people per kWh produced than nuclear.
So stop feeding your (and others') fears. If you want the safest, most efficient, base-load capable way of producing electricity we've come up with, you want nuclear.
Also, it took a combination a flood bigger than the dam was designed to control and seriously under-designing the dam and shoddy construction of that design and operating it poorly and failure to evacuate the flood-prone regions in order to cause this many loss of lives.
Also, it took a combination of an earthquake bigger than the plant was designed to withstand and the biggest tsunami wave in recorded history and the backup pumps flooding and failing and still there was no radiation-caused loss of life at Fukushima.
So let's tally up the deaths then, shall we: Direct deaths: Banqiao: 26.000 Fukushima: 0 Indirect deaths: Banqiao: 140.000 Fukushima: 0
No matter how anyone trembling in their pants at the thought of the invisible bogey-man radiation tries to spin it, nuclear power is safer than any other means of producing electricity we have - even when it goes badly wrong.
Authors (and musicians, and whoever else falls under copyright these days) have no right to make money off their products. They have an opportunity to do so, an opportunity that is denied anyone who does not hold the copyright to the piece in question.
There is no right to make money. There is only opportunity, and with copyright that opportunity is made exclusive to the copyright-holder.
Slashdot Mirror
Yeah. Dawn's ion engines (linked to in TFS) have a very high ISP (3100s), but an equally low thrust (90 mN).
As a comparison, the F-1 engines on the Saturn V Stage I-C had pretty low ISP (about 250s), but a massive 34 MN of thrust.
Basically you can have high ISP (electrical) or high thrust (chemical), but not both.
Unless you go VASIMR, of course, and we're not quite there yet.
Earth has 2-5 eruptions each year
That's off by a factor of ten.
From wikipedia: "Presently there are about 500 active volcanoes in the world – the majority following along the Pacific 'Ring of Fire' – and around 50 of these erupt each year.[6] The United States is home to 50 active volcanoes.[7] There are more than 1,500 potentially active volcanoes.[8] An estimated 500 million people live near active volcanoes.[9]"
UID 1 is CmdrTaco.
I'll fill in the 5-digit spot; waiting for the 4-digit reply.
As for scaling up the device, one need only look here to see its tremendous potential.
"Tremendous potential"? It needs 40-70 kV to lift its massive weight of 6 grams - what does its power source weigh?
And given the knowledge that capacitors with solid dielectrics work in a vacuum we can see that with higher K dielectrics, more advanced materials, and an on board power source such as a hybrid engine, such technology could be put to use to create a vehicle suitable for air, land, sea, or space travel.
Given enough handwavium, anything's possible.
I'll get on board with ionocrafts when they can actually lift themselves AND their powersource. Currently, that's not even theoretically possible without handwaving.
Yes, lifters are fine. As a science fair project for school kids.
For propulsion on a plane/space vehicle? Not so much.
They produce about a gram of lift per watt. So far, payloads as massive as 60 grams have been lifted. Next stop, the moon?
Also, the voltages needed for them to function are extremely high, 20-50 kV for the science-fair models. That kind of apparatus weighs orders of magnitude more than the lift generated.
And, to add insult to injury, they produce ozone when in use.
Not a very green (or realistic) alternative to rockets.
Tidied up the quote a bit, since it's delectable:
Now it is clear that anyone working with rocket fuels is outstandingly mad. I don't mean garden-variety crazy or a merely raving lunatic. I mean a record-shattering exponent of far-out insanity.
There are, after all, some chemicals that explode shatteringly, some that flame ravenously, some that corrode hellishly, some that poison sneakily, and some that stink stenchily. As far as I know, though, only liquid rocket fuels have all these delightful properties combined into one delectable whole.
Also, I'd like to also state my thanks to imbaczek for posting the link, 40 pages in and it's a page-turner :)
if the last U.S Shuttle was dismantled recently by the Obama's goverment then what's the next?
How about this one?
Additionally, not everything launched is a manned vehicle. Those satellites have to get up there somehow too.
Use the link in the summary to download the draft of the book, chapter 2 should give you enough of an overview to know at least some things you can do with PDL.
How do you keep a hole 13,100 ft deep melted when the average temperature in summer is -30C (-22F), and in winter -65C (-85F)?
The warmest it ever gets is about -12C (10F) - that's a record by the way, the warmest ever measured at Vostok station.
It's not exactly a resort, you know:
The warmest recorded temperature at Vostok is -12.2 C (10.0 F), which occurred on 11 January 2002.[10]
The coldest month was August 1987 with a mean temperature of -75.4 C (-103.7 F) and the warmest month was December 1989 with mean of -28 C (-18 F).[9]
In addition to the extremely cold temperatures, other factors make Vostok one of the most difficult places on Earth for human habitation:
* An almost complete lack of moisture in the air.
* An average windspeed of 5 m/s (18 km/h) (11 mph), sometimes rising to as high as 27 m/s (97 km/h)(60 mph).
* An acute lack of oxygen because of its high altitude at 3,488 meters (11,444 ft).
* A higher ionization of the air.
* A polar night that lasts approximately 130 days, from mid April to late August,[13] including 80 continuous days of civil polar night (i.e. too dark to read, during which the Sun is over 6 degrees below the horizon.)
(source wikipedia)
13,100 feet to the lake.
Been digging since 1974. That's 344 feet a year, or a foot per day. Hell, *I* could have dug quicker than that!
Or maybe they just had lots of problems, costs, setbacks, etc. associated with a 13,000 foot-long drill through a substance that nobody has ever drilled 13,000 down through?
It's also in the middle of the Antarctic, just about, and almost 900 miles from the Scott-Amundsen base at the South Pole. It's where the coldest temperature on earth has been measured, a whopping -128F (-89C). I'd love to see anyone dig a foot *that* day! :)
Reply to undo bad moderation.
Not yet, but one of them will. Sadly.
MCSE: Minsweeper Consultant and Solitaire Expert
At least that's what I was always told.
Indeed it was; by the CIA no less, using phoney companies.
The USSR was the world's largest producer of titanium (and Russia still is), but that doesn't mean they could afford using it or indeed that they had the skill to do so in their aerospace industry. Specifically for the MiG-25, they couldn't solve the problem of cracks in thin welded titanium so they went with the heavier nickel-alloy steel instead.
Also, another reason they went with nickel-alloy steel might be that most of the titanium produced in the USSR at the time the MiG-25 was constructed and built went to the navy and their Alfa class submarines.
The space shuttle isn't normally counted as an aircraft.
The A-12 was the precursor to the SR-71; the YF-12 was the prototype that became the SR-71. In essence, all three are the same aircraft.
The XB-70 was a prototype; there only ever were two of them. It broke Mach 3 on ten occasions.
X2 and X15, as you say, are experimental rocket planes, not production aircraft; they also had severely limited flight times.
The MiG-25/MiG-31 could theoretically sprint to Mach 3.2, but was never built to exceed Mach 2.8 - it couldn't handle the temperatures involved.
No, there ever really was one production aircraft that regularly (11,000+ hours at Mach 3+ according to official records) could do Mach 3+; the SR-71. While its true top speed is still classified, it was nowhere near the figures the GP believes; according to pilots accounts the plane couldn't do much more than Mach 3.5.
The official declassified top speed was Mach 3.2+.
If you read pilot's accounts, they regularly pushed the plane to Mach 3.5 when under missile threat.
I'm sure they would have pushed it further if it could go further.
Oh, I've done my homework. Question is, have you?
XB-70 was a prototype, they built two of them in total. They broke Mach 3 a grand total of ten times.
MiG-25, as I said, doesn't count. It could only theoretically handle Mach 3.
X-15 is a rocket, not a plane. It needed to be air-launched from a B-52.
Face it, there were never "lots of planes" that could do Mach 3+. There really ever was the SR-71.
As for your "theories" about the SR-71's top speed I can only say that you're wrong. The flight manual of the SR-71 has been declassified for quite a while now; I suggest you go read it: http://www.sr-71.org/blackbird/manual/.
Finally, a word or two on the MiG-25 and friction heating. The MiG-25 was built out of nickel-steel alloy because the soviets couldn't afford/couldn't work well with titanium. As you observed yourself, nickel alloys were also used on the X-15 to protect it from friction heat. So your claim that the MiG-25 was "capable of 3.2 without anything unusual" is bogus. It was built from 80% nickel steel alloy, if they had been able to afford it or work with it, it would have been built out of titanium like the SR-71.
Oh, and the SR-71 was engineered for somewhere around Mach 5 or 6.
Nonsense. From wikipedia:
Around Mach 3, the increased heating from the shock cone compression, plus the heating from the compressor fans, was enough to get the core air to high temperatures, and little fuel could be added in the combustion chamber without melting the turbine blades. This meant the whole compressor-combustor-turbine set-up in the core of the engine provided less power, and the Blackbird flew predominantly on air bypassed straight to the afterburners, forming a large ramjet effect. The maximum speed was limited by the specific maximum temperature for the compressor inlet of 800 F (427 C).
The SR-71 had enough problems coping with the temperatures generated at Mach 3, it was never designed for anything much above Mach 3.5.
lots of planes can do Mach 3
Really? Name three. MiG-25/31 don't count since they had a more than 50% chance of burning out both engines if they went over Mach 2.8 or so.
And, I talked to a retired traffic controller who once saw a '71 light up a civilian transponder so traffic could be vectored around it (it had an emergency apparently), they clocked it around 4000mph.
I'm glad that traffic controller is retired, because if he clocked an SR-71 at 4000mph, he was drinking on the job.
* The worldwide production of uranium in 2009 amounted to 50,572 tonnes.
* The worldwide production of coal is estimated to more than 7,000 million tonnes.
* Uranium is generally mined by in-situ leaching, which does not entail going underground at all.
* Coal is still mined by people going underground in many places.
* There's 4,000 cases of black lung from coal mining every year in the US alone (10,000+ in China).
* The major health hazard in uranium mining was radon gas inhalation. These days safety regulations and ventilation is such that the workers aren't exposed to more radon than in some homes.
Either way you try to look at these numbers, mining coal is more dangerous than mining uranium.
It's because most of us are bored to tears with "AMAGADNUCULARISBAD!".
If you actually look at statistics - you know, data; hard cold facts and figures - nuclear is the safest way of producing electricity we've come up with.
Coal/gas/oil are more polluting, solar/tidal/wind aren't base-load capable, and geo/hydro has its own set of problems, not least of which is killing a lot of people when dams go bust.
And all of them kill more people per kWh produced than nuclear.
So stop feeding your (and others') fears. If you want the safest, most efficient, base-load capable way of producing electricity we've come up with, you want nuclear.
Also, it took a combination a flood bigger than the dam was designed to control and seriously under-designing the dam and shoddy construction of that design and operating it poorly and failure to evacuate the flood-prone regions in order to cause this many loss of lives.
Also, it took a combination of an earthquake bigger than the plant was designed to withstand and the biggest tsunami wave in recorded history and the backup pumps flooding and failing and still there was no radiation-caused loss of life at Fukushima.
So let's tally up the deaths then, shall we:
Direct deaths: Banqiao: 26.000 Fukushima: 0
Indirect deaths: Banqiao: 140.000 Fukushima: 0
No matter how anyone trembling in their pants at the thought of the invisible bogey-man radiation tries to spin it, nuclear power is safer than any other means of producing electricity we have - even when it goes badly wrong.
Schlock Mercenary
Authors (and musicians, and whoever else falls under copyright these days) have no right to make money off their products. They have an opportunity to do so, an opportunity that is denied anyone who does not hold the copyright to the piece in question.
There is no right to make money. There is only opportunity, and with copyright that opportunity is made exclusive to the copyright-holder.