I guess Qantas wouldn't even need to purchase the overpriced A380, a 777-300ER might do the job just as well for a lot less. A little less capacity, but a lot lower operating costs, with ETOPS no problem operating it over the Pacific anymore and a far easier job finding suitable gates and airports for it. But I suppose if you already have it in your fleet, might as well go ahead and use it.
They are without overlap. You can't just swap aircraft types without serious infrastructure changes in an airline. Airplanes aren't cars.
Just what FedEx [planespotters.net] or UPS might want then, right?
No. The Mria is much larger than is often needed or even wanted (airport/handling restrictions), it has terrible fuel economy and doesn't fit within the fleet composition of FedEx or UPS. Again, you can't just switch airplane makes like you do with cars. There are training considerations, certifications, maintenance, parts availability, manufacturer support, etc. etc. Bigger isn't always better. Just ask Airbus about their A380F (total market flop).
Ukraine to what rescue? The demand being discussed here is for passenger aircraft in the 100-200 seat category for short-to-medium routes. Did I miss a recent Ukrainian aircraft in that category? Mria is basically a 1980s huge empty flying box, a completely different aircraft for a completely different job.
Aircraft aren't like cars, you can't just hop from one to the next. There are certifications, training, simulators, supply chain, support infrastructure, etc. etc. It's why low-cost carriers are total monocultures in terms of aircraft they use. Ryanair *only* flies the 737NG. Easyjet *only* flies the A320 family.
The source bases between Oracle ZFS and OpenZFS are still probably 90% identical. The disk format has changed recently, but you can still create an old-format pool to facilitate data interchange between the two and it'll work without a hitch (if not, file a bug).
Scramjets are, by definition, air-breathing, and are therefore not rocket engines. Admittedly a nit of terminology, but the/. crowd are generally more technically/engineering minded people and those tend to care about proper use of jargon.
You see, this is the funny bit. If you wanted to make it representative of the general population, you'd need to hire about 5,000 MORE whites and fire about 8,000 asians. But of course, facts are wildly unpopular when people just want to play identity politics and hate on the majority.
Did the person who wrote TFA even look for consistency in their article? Who the fuck says you need to build your own? There are tons of options for buying pre-built gaming PCs, so getting into PCs is no more difficult than knowing how to order shit online. And did he just seriously mention gaming and Apple computers in the same paragraph? Just casually browsing newegg I managed to configure a custom pre-built PC in 5 minutes that would absolutely skull fuck anything currently sold by Apple at twice the price in gaming performance.
The question is: will Samsung integrate those pearls? Or would this Solaris platform be shelved?
Shelving the Illumos core of SmartOS (Joyent's cloud OS platform) would essentially completely destroy all value in Joyent. Its distinctive cloud technology is intimately tied to Zones.
The FMS doesn't navigate, it assists pilots in navigating. Yeah, it's cute while flying on the pretty magenta line, but if you've ever flown in real life, you'd know that things rarely go exactly according to plan each time. Diversions, directs, holdings, offsets, vectors, changes in approaches, go-arounds, terrain avoidance, all ultimately end up as decisions by pilots. The FMS is a helpful automation tool, but it's a tool for the pilots. It is in no sense autonomous.
And give me a break on "handle emergencies". The best I've ever seen an FMS do is give you an engine-out SID or max cruise performance adjustment. It won't fly the aircraft for you, it won't solve the problem for you and ultimately it won't decide for you. It is a means, not an end.
An autopilot is a relatively straightforward and simple system. It has a small handful of fixed modes and is programmed, adjusted and continuously monitored by a human pilot in flight. If an autopilot starts messing things up (and this happens more often than you'd think), the human pilot takes over and stabilizes things. If an emergency occurs, the human takes over. If a helicopter loses its engine, the pilot judges a safe landing spot and executes an autorotation landing. An autonomous drone is way past these. Besides doing the whole flight without human intervention or oversight, it needs to be able to make decisions when shit starts hitting the fan.
Unfortunately for section (b)(1) to apply, section (b)(2) has to apply as well (that's why there's an "and" at the end of (b)(1)). Primarily, section (b) is meant for people like traveling salesmen, so that they can fly themselves and possibly their colleagues, but not receive compensation for the carriage of people or cargo, i.e. the flying mustn't be their primary job description. Also, the FAA regs do not care one bit about whether you're working for the USPS (directly or indirectly), employment/contracting details or anything other than whether money has changed hands. Anyway, I wouldn't be surprised if the USPS has some special exemptions in the laws explicitly allowing it to circumvent PPL limitations. Wouldn't be the first time the government put in exceptions to the rules for itself.
Just to clarify, your father, holder of a private pilot certificate, is employed or works for hire (i.e. receives compensation) to fly mail? If so, then that would seem to be a direct violation of 14 CFR 61.113. Are you sure he isn't a holder of a CPL?
Well, sort of, but you missed what I told you, that a pound-for-pound, there's really not much difference in terms of power between a turbofan engine core (often referred to as the gas generator, loosely) and an electric motor.
If you want to go full-retard, why don't we talk about the amount of energy we can get from nuclear reactions of Lithium atoms versus carbon atoms? It's just as relevant as this spewing crap.
Gee I hope you're not doing nuclear reactions in your fuel cell.
Compared to advanced piston engine airliners of the 1950s, current jet airliners are only marginally more efficient per passenger-mile.
Yes. But the pistons were also a lot slower, noisier, less comfortable and less reliable, all of which are rather important details to airlines.
At lower-speeds, props are much more efficient than turbofans, and props can of course be easily driven by electric motors.
And you know what's most efficient? Not going anywhere. If there's a flight that takes 4 hours and another that takes 8 hours, I'll strongly consider the 4 hour one, even if it costs more. Moreover, the airline sees it like this: how many passenger-miles can I do with this type per year? That equates directly to profit. Slower airplane = fewer seats sold per year = lower profit margin. Even if your shiny new airplane is twice as efficient, if it's half as slow, you've not actually gained anything. Why do you think airlines buy jets for anything above regional?
At lower-speeds, props are much more efficient than turbofans, and props can of course be easily driven by electric motors.
You can also drive a fan using an electric motor just as well.
And electrically-driven aircraft is incredibly simplified, to the point that airlines would want them for their lower maintenance costs and less downtime, even if the efficiency wasn't substantially better
Well, maybe. It depends on the details. For one thing, the FAA won't let you get away with just one fuel cell system. You're gonna need two independent ones, or else you won't be allowed to put any passengers on it. It's unclear if it's gonna be simpler, require less maintenance or be more reliable, as no such aircraft are even on the serious drawing board (I don't mean concepts, I mean actual detailed designs for flight worthy hardware).
Actually turbine engines vs electrical motors aren't all that much different in terms of power-to-weight ratio. You can design a ultra-high-bypass turbofan that's electrically driven and suffer no loss of speed. It'll just be a fan and the turbine engine core is replaced with an electric motor. It's the battery weights that kill the idea. ATM far too heavy and too many operational complications to be practical.
You're forgetting how inefficient turbofan engines are at part-throttle conditions.
Proportions matter here. Turbine engines run in cruise at around 95% of rated RPM and about 3/4 to 4/5 of maximum thrust. In those regions, they are pretty much at the efficiency plateau. Those things aren't designed by idiots.
As for idling, yeah, they're inefficient. Everybody knows this, which is why partial-engine taxis are common nowadays and even so the overhead isn't so bad. I just did a quick calculation with my dispatch tool and a 737-800 on a relatively short hop of ~1.5 hours (only about 1 hour actual air time). A 20 minute taxi-out and 8-minute taxi-in (all engines running) comes to only about 9% of the trip fuel (6000 lbs trip, 500 lbs taxi). Would airlines be happy to reduce it? Definitely. But is it some huge environmental saving? Not really. And keep in mind, this is short-haul, so about as high as it gets. On longer routes the taxi falls quite dramatically. On a transatlantic route it's only about 2% of the trip fuel and transatlantic is quite short by long-haul standards (only ~6 hrs flight time).
A turboprop is basically a very high bypass turbofan with a lower exhaust velocity. The means its propulsive efficiency is best at lower air speeds. Maximizing propulsive efficiency, in the simplest terms, is simply about using as much of the energy provided by an engine to displace the aircraft forward and as little to displace the surrounding air backward - you want to get the aircraft from point A to point B, not the static air in reverse. Hence, propulsive efficiency is best when effective exhaust velocity is as close to true airspeed as possible. Propeller effective exhaust velocity is lower than for turbofans, so they work better at lower speeds than turbofans do. It actually has relatively little to do with altitude and fairly little to do with how the mechanical power to drive a prop/fan is generated.
instead of having to be optimized across a wide range of RPM
But that's not how turbine engines work. This isn't your car. Typically turbine engines operate 85-100% of their rated rpm and in cruise it's closer to 95-100%. Oh and continually stopping and starting turbine engines is one of the worst things you can do to them, because that's when they experience most of their wear.
A liquid fuel combustion engine drives a generator that produces electricity, and that electricity is used to drive electric motors that provide propulsion.
In that case, job done. You're basically describing the thermodynamic cycle of a high-bypass turbofan or turboprop engine, minus all the electrical efficiency losses in between. Gas generator driving a turbine which produces mechanical power to drive a bypass fan or prop. And you're misunderstanding the reason why we have multiple engines on passenger aircraft. It isn't because we can't build em large enough. It's because everything fails. That's why you have two of everything in aircraft. Two engines, two fully independent electrical systems, two sets of flight control actuators, yes even the two pilots. Heck, it's also the reason why landing gear has least two sets of wheels on each axle.
An escape tug can be reused between any interplanetary missions for GTO and cislunar traffic. It would lower the requirements for the interplanetary craft while simultaneously sharing common in-space infrastructure with other projects (heavy satellite tugging, lunar traffic etc.).
Let me be clear. I like the idea, but you're describing infrastructure that's just way outside of practicality right now. In 20-30 years? Maybe. But in the next decade. Highly unlikely.
But if you want to escape from cislunar space using electric propulsion, you could always start from one of the Lagrange points, for example. Or from a high Earth orbit.
But that's the crucial bit. Getting to any Lagrange point or high Earth orbit is the costly bit. LEO to GTO is 2.5 km/s. And it's another 0.7 km/s to the Moon's orbital radius and that's only at apogee. To circularize at GEO is more than a simple escape & Mars transfer together - that's the power of the Oberth effect. Using the slow spiral-out method, you can almost double the delta-V requirements. That's why even Ad Astra says on their website that for practical human spaceflight, you'd need a nuclear reactor.
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I guess Qantas wouldn't even need to purchase the overpriced A380, a 777-300ER might do the job just as well for a lot less. A little less capacity, but a lot lower operating costs, with ETOPS no problem operating it over the Pacific anymore and a far easier job finding suitable gates and airports for it. But I suppose if you already have it in your fleet, might as well go ahead and use it.
The categories aren't without overlaps.
They are without overlap. You can't just swap aircraft types without serious infrastructure changes in an airline. Airplanes aren't cars.
Just what FedEx [planespotters.net] or UPS might want then, right?
No. The Mria is much larger than is often needed or even wanted (airport/handling restrictions), it has terrible fuel economy and doesn't fit within the fleet composition of FedEx or UPS. Again, you can't just switch airplane makes like you do with cars. There are training considerations, certifications, maintenance, parts availability, manufacturer support, etc. etc. Bigger isn't always better. Just ask Airbus about their A380F (total market flop).
Ukraine to what rescue? The demand being discussed here is for passenger aircraft in the 100-200 seat category for short-to-medium routes. Did I miss a recent Ukrainian aircraft in that category? Mria is basically a 1980s huge empty flying box, a completely different aircraft for a completely different job.
Aircraft aren't like cars, you can't just hop from one to the next. There are certifications, training, simulators, supply chain, support infrastructure, etc. etc. It's why low-cost carriers are total monocultures in terms of aircraft they use. Ryanair *only* flies the 737NG. Easyjet *only* flies the A320 family.
The source bases between Oracle ZFS and OpenZFS are still probably 90% identical. The disk format has changed recently, but you can still create an old-format pool to facilitate data interchange between the two and it'll work without a hitch (if not, file a bug).
CDDL, license changes aren't allowed (because the code base came from Sun).
Scramjets are, by definition, air-breathing, and are therefore not rocket engines. Admittedly a nit of terminology, but the /. crowd are generally more technically/engineering minded people and those tend to care about proper use of jargon.
White: 19,809
Black: 628
Asian: 9,924
Hispanic: 1,428
Hawaiian/Pacific: 61
American Indian: 41
You see, this is the funny bit. If you wanted to make it representative of the general population, you'd need to hire about 5,000 MORE whites and fire about 8,000 asians. But of course, facts are wildly unpopular when people just want to play identity politics and hate on the majority.
Did the person who wrote TFA even look for consistency in their article? Who the fuck says you need to build your own? There are tons of options for buying pre-built gaming PCs, so getting into PCs is no more difficult than knowing how to order shit online. And did he just seriously mention gaming and Apple computers in the same paragraph? Just casually browsing newegg I managed to configure a custom pre-built PC in 5 minutes that would absolutely skull fuck anything currently sold by Apple at twice the price in gaming performance.
"Mom", "Love" and "Screen door" are registered trademarks of Mom Corp.
The question is: will Samsung integrate those pearls? Or would this Solaris platform be shelved?
Shelving the Illumos core of SmartOS (Joyent's cloud OS platform) would essentially completely destroy all value in Joyent. Its distinctive cloud technology is intimately tied to Zones.
The FMS doesn't navigate, it assists pilots in navigating. Yeah, it's cute while flying on the pretty magenta line, but if you've ever flown in real life, you'd know that things rarely go exactly according to plan each time. Diversions, directs, holdings, offsets, vectors, changes in approaches, go-arounds, terrain avoidance, all ultimately end up as decisions by pilots. The FMS is a helpful automation tool, but it's a tool for the pilots. It is in no sense autonomous.
And give me a break on "handle emergencies". The best I've ever seen an FMS do is give you an engine-out SID or max cruise performance adjustment. It won't fly the aircraft for you, it won't solve the problem for you and ultimately it won't decide for you. It is a means, not an end.
FMS != A/P. They do different tasks.
An autopilot is a relatively straightforward and simple system. It has a small handful of fixed modes and is programmed, adjusted and continuously monitored by a human pilot in flight. If an autopilot starts messing things up (and this happens more often than you'd think), the human pilot takes over and stabilizes things. If an emergency occurs, the human takes over. If a helicopter loses its engine, the pilot judges a safe landing spot and executes an autorotation landing. An autonomous drone is way past these. Besides doing the whole flight without human intervention or oversight, it needs to be able to make decisions when shit starts hitting the fan.
Unfortunately for section (b)(1) to apply, section (b)(2) has to apply as well (that's why there's an "and" at the end of (b)(1)). Primarily, section (b) is meant for people like traveling salesmen, so that they can fly themselves and possibly their colleagues, but not receive compensation for the carriage of people or cargo, i.e. the flying mustn't be their primary job description. Also, the FAA regs do not care one bit about whether you're working for the USPS (directly or indirectly), employment/contracting details or anything other than whether money has changed hands. Anyway, I wouldn't be surprised if the USPS has some special exemptions in the laws explicitly allowing it to circumvent PPL limitations. Wouldn't be the first time the government put in exceptions to the rules for itself.
He does the U.S. mail run to McCartney
Just to clarify, your father, holder of a private pilot certificate, is employed or works for hire (i.e. receives compensation) to fly mail? If so, then that would seem to be a direct violation of 14 CFR 61.113. Are you sure he isn't a holder of a CPL?
Well, sort of, but you missed what I told you, that a pound-for-pound, there's really not much difference in terms of power between a turbofan engine core (often referred to as the gas generator, loosely) and an electric motor.
If you want to go full-retard, why don't we talk about the amount of energy we can get from nuclear reactions of Lithium atoms versus carbon atoms? It's just as relevant as this spewing crap.
Gee I hope you're not doing nuclear reactions in your fuel cell.
Compared to advanced piston engine airliners of the 1950s, current jet airliners are only marginally more efficient per passenger-mile.
Yes. But the pistons were also a lot slower, noisier, less comfortable and less reliable, all of which are rather important details to airlines.
At lower-speeds, props are much more efficient than turbofans, and props can of course be easily driven by electric motors.
And you know what's most efficient? Not going anywhere. If there's a flight that takes 4 hours and another that takes 8 hours, I'll strongly consider the 4 hour one, even if it costs more. Moreover, the airline sees it like this: how many passenger-miles can I do with this type per year? That equates directly to profit. Slower airplane = fewer seats sold per year = lower profit margin. Even if your shiny new airplane is twice as efficient, if it's half as slow, you've not actually gained anything. Why do you think airlines buy jets for anything above regional?
At lower-speeds, props are much more efficient than turbofans, and props can of course be easily driven by electric motors.
You can also drive a fan using an electric motor just as well.
And electrically-driven aircraft is incredibly simplified, to the point that airlines would want them for their lower maintenance costs and less downtime, even if the efficiency wasn't substantially better
Well, maybe. It depends on the details. For one thing, the FAA won't let you get away with just one fuel cell system. You're gonna need two independent ones, or else you won't be allowed to put any passengers on it. It's unclear if it's gonna be simpler, require less maintenance or be more reliable, as no such aircraft are even on the serious drawing board (I don't mean concepts, I mean actual detailed designs for flight worthy hardware).
Actually turbine engines vs electrical motors aren't all that much different in terms of power-to-weight ratio. You can design a ultra-high-bypass turbofan that's electrically driven and suffer no loss of speed. It'll just be a fan and the turbine engine core is replaced with an electric motor. It's the battery weights that kill the idea. ATM far too heavy and too many operational complications to be practical.
You're forgetting how inefficient turbofan engines are at part-throttle conditions.
Proportions matter here. Turbine engines run in cruise at around 95% of rated RPM and about 3/4 to 4/5 of maximum thrust. In those regions, they are pretty much at the efficiency plateau. Those things aren't designed by idiots.
As for idling, yeah, they're inefficient. Everybody knows this, which is why partial-engine taxis are common nowadays and even so the overhead isn't so bad. I just did a quick calculation with my dispatch tool and a 737-800 on a relatively short hop of ~1.5 hours (only about 1 hour actual air time). A 20 minute taxi-out and 8-minute taxi-in (all engines running) comes to only about 9% of the trip fuel (6000 lbs trip, 500 lbs taxi). Would airlines be happy to reduce it? Definitely. But is it some huge environmental saving? Not really. And keep in mind, this is short-haul, so about as high as it gets. On longer routes the taxi falls quite dramatically. On a transatlantic route it's only about 2% of the trip fuel and transatlantic is quite short by long-haul standards (only ~6 hrs flight time).
to prevent supersonic airflow
Actually, supersonic airflow at the fan tip is pretty common. Has been for at least 30 years.
RB211-535E4:
A turboprop is basically a very high bypass turbofan with a lower exhaust velocity. The means its propulsive efficiency is best at lower air speeds. Maximizing propulsive efficiency, in the simplest terms, is simply about using as much of the energy provided by an engine to displace the aircraft forward and as little to displace the surrounding air backward - you want to get the aircraft from point A to point B, not the static air in reverse. Hence, propulsive efficiency is best when effective exhaust velocity is as close to true airspeed as possible. Propeller effective exhaust velocity is lower than for turbofans, so they work better at lower speeds than turbofans do. It actually has relatively little to do with altitude and fairly little to do with how the mechanical power to drive a prop/fan is generated.
instead of having to be optimized across a wide range of RPM
But that's not how turbine engines work. This isn't your car. Typically turbine engines operate 85-100% of their rated rpm and in cruise it's closer to 95-100%. Oh and continually stopping and starting turbine engines is one of the worst things you can do to them, because that's when they experience most of their wear.
A liquid fuel combustion engine drives a generator that produces electricity, and that electricity is used to drive electric motors that provide propulsion.
In that case, job done. You're basically describing the thermodynamic cycle of a high-bypass turbofan or turboprop engine, minus all the electrical efficiency losses in between. Gas generator driving a turbine which produces mechanical power to drive a bypass fan or prop. And you're misunderstanding the reason why we have multiple engines on passenger aircraft. It isn't because we can't build em large enough. It's because everything fails. That's why you have two of everything in aircraft. Two engines, two fully independent electrical systems, two sets of flight control actuators, yes even the two pilots. Heck, it's also the reason why landing gear has least two sets of wheels on each axle.
An escape tug can be reused between any interplanetary missions for GTO and cislunar traffic. It would lower the requirements for the interplanetary craft while simultaneously sharing common in-space infrastructure with other projects (heavy satellite tugging, lunar traffic etc.).
Let me be clear. I like the idea, but you're describing infrastructure that's just way outside of practicality right now. In 20-30 years? Maybe. But in the next decade. Highly unlikely.
But if you want to escape from cislunar space using electric propulsion, you could always start from one of the Lagrange points, for example. Or from a high Earth orbit.
But that's the crucial bit. Getting to any Lagrange point or high Earth orbit is the costly bit. LEO to GTO is 2.5 km/s. And it's another 0.7 km/s to the Moon's orbital radius and that's only at apogee. To circularize at GEO is more than a simple escape & Mars transfer together - that's the power of the Oberth effect. Using the slow spiral-out method, you can almost double the delta-V requirements. That's why even Ad Astra says on their website that for practical human spaceflight, you'd need a nuclear reactor.