To be honest, I often wonder why those tugs didn't go electric years ago, like giant golf carts or something.
Some did. Ultimately, the move to electric might be inevitable for all aircraft tugs, given the unique requirements of airports (such as the weight of the batteries actually being a positive, since aircraft tugs are commonly ballasted down to enhance traction).
Engines are part of the story, but if you look at the CRJ-200's design vs what it came from (Challenger 600), the jaw just drops. It's the exact *same* wing, almost the same engines, but a much longer fuselage (68'4'' vs 87'10''), so empty weight jumped by almost 5 tons (as did max gross). Oh no leading edge slats, only flaps. So at any meaningful loading, you're looking a rotation speed of around 145 knots. Combine that with the underpowered engines, some elevation above sea level & heat and you're looking at barely being able to take off on an 8000 ft runway. Oh and of course no autothrottles on these puppies, so be careful when you set your takeoff power if you don't want to cook the turbines.
Ah yes, the good old underpowered CRJ, the dog turd of jet airliners when it comes to performance. Look no further for an example of what happens when you knock a one wing off of two business jets and glue them together. Make no mistake, I love the CRJ, but better keep the hops in it short. Anything much above FL200 and you can kiss your climb rate goodbye. Oh and make sure you've got plenty of runway, cause this thing thinks it's a 747 when you look at the takeoff speed table.
Glad I could help. Just FYI, GPS has been in use in aviation since the 90s (example). Full glass panel units with integrated GPS (example) have been around for over 10 years. On airliners, GPS integration usually manifests simply as new indications of the flight management system interfaces (+ improved capabilities of the system, note "GPS PRIMARY" on the linked picture and "ESTIMATED" accuracy of +-0.09NM). Generally, airlines don't like to alter their cockpits too much.
"GPS" is used in the article simply because it's a nice buzzword that non-aviation people know, but it doesn't necessarily pertain to how the exact method of navigation is implemented in the aircraft. In aviation, the umbrella term for this kind of navigation is "RNAV", a somewhat counterintuitive backronym for "area navigation". Basically, it means your aircraft is capable of determining its position (subject to some quantifiable error) and navigating to an arbitrary set of geographic coordinates, rather than following ground-based navigational beacons. How the position is determined depends on the exact kind of RNAV system you have installed. Most modern airliners have a highly accurate dual- or triple-redundant inertial reference system (IRS), in addition to (usually) two GPS receivers and a couple of ground-based navigational aid receivers (usually VOR/DME). The aircraft's flight management computers (again, usually at least two) then use a complicated set of filtering algorithms to combine these inputs and compute an actual aircraft position and a CEP (circular error probable) value, which is then interpreted and displayed in the cockpit as a navigational precision value. RNAV procedures are designed for a minimum required navigational precision. Therefore, the loss of GPS reception doesn't manifest in the aircraft suddenly losing all sense of where it is located. Instead, the FMCs simply interpret it as the loss of a source of position data and carry on using the remaining good sources. Even without GPS, the inertial reference systems are highly accurate and rarely exceed more than +-1NM positional error even on very long flights. To further limit IRS drift, most modern FMCs automatically use the ground-based navigational aid receivers for periodic adjustments of the IRS platforms. They autotune a nearby VOR/DME station, read off magnetic radial and distance information and use that to correct IRS drift.
This all before we even get into systems such as WAAS or SBAS, which are specifically designed to quickly detect and correct GPS transmission errors. High-quality aircraft GPS systems also include a set of features called RAIM (Receiver Autonomous Integrity Monitoring), which means the GPS equipment will perform a receiver and predictive signal integrity check prior to commencing a critical phase of flight that might be dependent on the GPS equipment operating correctly.
Simple: mandate a Mode S or ADS-B Out transponder that automatically transmits your aircraft registration. Soon as you enter controlled airspace, even without radio contact, you get billed and get it nice and collated at the end of the month in your mail. Have a nice day citizen.
Aircraft cabins never exceed 8,000 ft cabin altitude and are often pressurized to between 6,000 - 7,000 ft. The FAA allows non-pressurized aircraft without oxygen up to 12,000 ft (EASA up to 10,000 ft), so I doubt much of anything happens at 8,000 ft. In fact, I flew at 9,000 ft for 7 hours last Saturday and felt fresh as a flower.
Ever fly into Denver, CO? Unless you do it regularly, you'll feel fatigued for a day or so after arrival.
Yep and never felt it. You sure you're not just jet lagged?
PC gamers are notorious for overestimating power supply requirements. The wattage craze is completely unwarranted UNLESS you overclock. At stock clocks, the cards are actually pretty power efficient. See this graph for example. Under max load, a GTX 1070 draws maybe 150W by itself. Combine that with a 65W TDP CPU (e.g. Core i5 7600) and you're only at 215W at max load. Add in 5W for memory and 15W for the HDD and you can still fit yourself into 235W, 10W less than 245W. Now consider that the XBox Scorpio's CPU & GPU will be lower clocked than your average PC rig and you can see how they can fit into 245W. Also see this short informative video on the same subject.
What confused me is your obvious lack of understanding of jet propulsion. See below.
The question posed was, "[h]ow can a jet be electric?", not what's efficient and realistic model for air transport. Stop assuming!
Your response makes little sense to answer the question, hence the confusion. It's like you think "jet propulsion" must require combustion. It doesn't. In fact, in modern jet engines, the vast majority of their thrust (not power) doesn't come from combusted exhaust gas. To make a electric jet engine, all you have to do is cut out the turbine engine core and replace with a powerful electric motor. What you are left with is a compressor fan feeding a propulsive nozzle. No need to go into weird atmospheric chemistry territory to create a pointless intermediary fuel. Just drive the fan electrically and be done with it.
I wasn't sure what he was proposing, so that's why I asked. If he meant to create combustible fuels from the atmosphere by inputting energy and then just using said fuel for propulsion, then that's at least not apriori not thermodynamically impossible, assuming that the produced fuel isn't used to generate more energy than was put in. What makes it silly, however, is the inefficiency of this idea.
The Concorde was extremely wasteful. Just ran the numbers on this using a modern plane. On a *very* short flight from London Gatwick to Amsterdam (route length just 240nm, about 40 minutes flight time) using an Airbus A319 burns around 2050 kg of fuel. Assuming a 20-minute taxi (15 minutes out, 5 minutes in, two-engine taxi both ways) consumes 200 kg. That's pretty close to the worst case and even so it's only about 10%. On the other hand, on aircraft of this size, the common rule of thumb of extra weight vs enroute fuel burn is that carrying an extra 1000 kg of weight equates to about an extra 100 kg of fuel burn per hour. So depending on the extra weight of the batteries, electric motors and gears, if it is a decent fraction of a ton, you'll have decreased your savings easily by maybe 50-100 kg (and the cost grows linearly with flight length, unlike relative taxi fuel cost, which decreases with flight length).
A jet can be fully electric if it uses the atmosphere from the intake to create a combustible fuel and then combusts it. This would require a lot of energy but it is possible since our atmosphere can be broken down into combustible components.
Please explain this miracle of thermodynamics-defying chemistry in more detail. I would really like to have free energy.
They are also decidedly tight-lipped about this on their own website, which contains nothing but wishy-washy rhetoric, much in the vein of TFA and this summary. No hard data, no technical details, not even a clarification of what terms like "hybrid" mean. It might be completely legit, but so far this gives off the distinct smell of venture bullshit - seems to fall into the same category of feel-good investment blackholes projects like AirCarbon and Solar Roadways.
It actually sounds more like you have no clue what "jet propulsion" means. The render in the article, while admittedly cartoonish, does actually seem to represent the concept of an e-fan, i.e. an electrically driven compressor fan.
Alright, so we have finally arrived at the insults. And "butthurt"? Seeing as you're the one wanting to throw insults, feels to me like you're projecting.
Maybe you should have asked me "why do you think this is a bad idea?". Then you wouldn't have to assume I wanted you to take my word for it.
Ah yes, the classic "but they mocked the Wright brothers!" excuse. To that, all I can summon is the power of Carl Sagan:
But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also laughed at Bozo the Clown.
This circular runway idea falls straight into the "clown" category.
You don't have to try every dumb idea before concluding that it's dumb. Otherwise, I propose you try to stick a rusty nail in your ear. Hey, you don't know until you try, right?
You should conclude that it won't work by understanding the problems with it. And you'll figure those out by either learning about how and why things are done a certain way in aviation, or talking to somebody who does.
That part was my opinion, not some broad consensus. Of course you'll find people fapping about stupid ideas everywhere just because they sound "cool" at a first glance. Look at the mountain of shitty kickstarters that promised the world, raised huge sums and ultimately ended up going bust, because "cool" doesn't necessarily translate into "viable".
The rotors appear to be pretty tiny and are probably nowhere near large enough to generate significant lift in auto-rotation. That is assuming that the blades even feature adjustable blade pitch (which is needed to induce autorotation on a propeller designed for thrust).
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To be honest, I often wonder why those tugs didn't go electric years ago, like giant golf carts or something.
Some did. Ultimately, the move to electric might be inevitable for all aircraft tugs, given the unique requirements of airports (such as the weight of the batteries actually being a positive, since aircraft tugs are commonly ballasted down to enhance traction).
Engines are part of the story, but if you look at the CRJ-200's design vs what it came from (Challenger 600), the jaw just drops. It's the exact *same* wing, almost the same engines, but a much longer fuselage (68'4'' vs 87'10''), so empty weight jumped by almost 5 tons (as did max gross). Oh no leading edge slats, only flaps. So at any meaningful loading, you're looking a rotation speed of around 145 knots. Combine that with the underpowered engines, some elevation above sea level & heat and you're looking at barely being able to take off on an 8000 ft runway. Oh and of course no autothrottles on these puppies, so be careful when you set your takeoff power if you don't want to cook the turbines.
Ah yes, the good old underpowered CRJ, the dog turd of jet airliners when it comes to performance. Look no further for an example of what happens when you knock a one wing off of two business jets and glue them together. Make no mistake, I love the CRJ, but better keep the hops in it short. Anything much above FL200 and you can kiss your climb rate goodbye. Oh and make sure you've got plenty of runway, cause this thing thinks it's a 747 when you look at the takeoff speed table.
Glad I could help. Just FYI, GPS has been in use in aviation since the 90s (example). Full glass panel units with integrated GPS (example) have been around for over 10 years. On airliners, GPS integration usually manifests simply as new indications of the flight management system interfaces (+ improved capabilities of the system, note "GPS PRIMARY" on the linked picture and "ESTIMATED" accuracy of +-0.09NM). Generally, airlines don't like to alter their cockpits too much.
"GPS" is used in the article simply because it's a nice buzzword that non-aviation people know, but it doesn't necessarily pertain to how the exact method of navigation is implemented in the aircraft. In aviation, the umbrella term for this kind of navigation is "RNAV", a somewhat counterintuitive backronym for "area navigation". Basically, it means your aircraft is capable of determining its position (subject to some quantifiable error) and navigating to an arbitrary set of geographic coordinates, rather than following ground-based navigational beacons. How the position is determined depends on the exact kind of RNAV system you have installed. Most modern airliners have a highly accurate dual- or triple-redundant inertial reference system (IRS), in addition to (usually) two GPS receivers and a couple of ground-based navigational aid receivers (usually VOR/DME). The aircraft's flight management computers (again, usually at least two) then use a complicated set of filtering algorithms to combine these inputs and compute an actual aircraft position and a CEP (circular error probable) value, which is then interpreted and displayed in the cockpit as a navigational precision value. RNAV procedures are designed for a minimum required navigational precision. Therefore, the loss of GPS reception doesn't manifest in the aircraft suddenly losing all sense of where it is located. Instead, the FMCs simply interpret it as the loss of a source of position data and carry on using the remaining good sources. Even without GPS, the inertial reference systems are highly accurate and rarely exceed more than +-1NM positional error even on very long flights. To further limit IRS drift, most modern FMCs automatically use the ground-based navigational aid receivers for periodic adjustments of the IRS platforms. They autotune a nearby VOR/DME station, read off magnetic radial and distance information and use that to correct IRS drift. This all before we even get into systems such as WAAS or SBAS, which are specifically designed to quickly detect and correct GPS transmission errors. High-quality aircraft GPS systems also include a set of features called RAIM (Receiver Autonomous Integrity Monitoring), which means the GPS equipment will perform a receiver and predictive signal integrity check prior to commencing a critical phase of flight that might be dependent on the GPS equipment operating correctly.
Simple: mandate a Mode S or ADS-B Out transponder that automatically transmits your aircraft registration. Soon as you enter controlled airspace, even without radio contact, you get billed and get it nice and collated at the end of the month in your mail. Have a nice day citizen.
Ever fly into Denver, CO? Unless you do it regularly, you'll feel fatigued for a day or so after arrival.
Yep and never felt it. You sure you're not just jet lagged?
They do. I believe that they run at 0.7 atmospheres. It makes people sleepy and docile.
Even if it did (and I don't believe it does), that's not the point behind depressurizing the cabin.
PC gamers are notorious for overestimating power supply requirements. The wattage craze is completely unwarranted UNLESS you overclock. At stock clocks, the cards are actually pretty power efficient. See this graph for example. Under max load, a GTX 1070 draws maybe 150W by itself. Combine that with a 65W TDP CPU (e.g. Core i5 7600) and you're only at 215W at max load. Add in 5W for memory and 15W for the HDD and you can still fit yourself into 235W, 10W less than 245W. Now consider that the XBox Scorpio's CPU & GPU will be lower clocked than your average PC rig and you can see how they can fit into 245W. Also see this short informative video on the same subject.
Which is why I wrote it, dummy! -_-
What confused me is your obvious lack of understanding of jet propulsion. See below.
The question posed was, "[h]ow can a jet be electric?", not what's efficient and realistic model for air transport. Stop assuming!
Your response makes little sense to answer the question, hence the confusion. It's like you think "jet propulsion" must require combustion. It doesn't. In fact, in modern jet engines, the vast majority of their thrust (not power) doesn't come from combusted exhaust gas. To make a electric jet engine, all you have to do is cut out the turbine engine core and replace with a powerful electric motor. What you are left with is a compressor fan feeding a propulsive nozzle. No need to go into weird atmospheric chemistry territory to create a pointless intermediary fuel. Just drive the fan electrically and be done with it.
I wasn't sure what he was proposing, so that's why I asked. If he meant to create combustible fuels from the atmosphere by inputting energy and then just using said fuel for propulsion, then that's at least not apriori not thermodynamically impossible, assuming that the produced fuel isn't used to generate more energy than was put in. What makes it silly, however, is the inefficiency of this idea.
See countries using decimal comma.
The Concorde was extremely wasteful. Just ran the numbers on this using a modern plane. On a *very* short flight from London Gatwick to Amsterdam (route length just 240nm, about 40 minutes flight time) using an Airbus A319 burns around 2050 kg of fuel. Assuming a 20-minute taxi (15 minutes out, 5 minutes in, two-engine taxi both ways) consumes 200 kg. That's pretty close to the worst case and even so it's only about 10%. On the other hand, on aircraft of this size, the common rule of thumb of extra weight vs enroute fuel burn is that carrying an extra 1000 kg of weight equates to about an extra 100 kg of fuel burn per hour. So depending on the extra weight of the batteries, electric motors and gears, if it is a decent fraction of a ton, you'll have decreased your savings easily by maybe 50-100 kg (and the cost grows linearly with flight length, unlike relative taxi fuel cost, which decreases with flight length).
A jet can be fully electric if it uses the atmosphere from the intake to create a combustible fuel and then combusts it. This would require a lot of energy but it is possible since our atmosphere can be broken down into combustible components.
Please explain this miracle of thermodynamics-defying chemistry in more detail. I would really like to have free energy.
which is presumably what these guys did
They are also decidedly tight-lipped about this on their own website, which contains nothing but wishy-washy rhetoric, much in the vein of TFA and this summary. No hard data, no technical details, not even a clarification of what terms like "hybrid" mean. It might be completely legit, but so far this gives off the distinct smell of venture bullshit - seems to fall into the same category of feel-good investment blackholes projects like AirCarbon and Solar Roadways.
It actually sounds more like you have no clue what "jet propulsion" means. The render in the article, while admittedly cartoonish, does actually seem to represent the concept of an e-fan, i.e. an electrically driven compressor fan.
Alright, so we have finally arrived at the insults. And "butthurt"? Seeing as you're the one wanting to throw insults, feels to me like you're projecting. Maybe you should have asked me "why do you think this is a bad idea?". Then you wouldn't have to assume I wanted you to take my word for it.
But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also laughed at Bozo the Clown.
This circular runway idea falls straight into the "clown" category.
You don't have to try every dumb idea before concluding that it's dumb. Otherwise, I propose you try to stick a rusty nail in your ear. Hey, you don't know until you try, right?
You should conclude that it won't work by understanding the problems with it. And you'll figure those out by either learning about how and why things are done a certain way in aviation, or talking to somebody who does.
Runway identifiers are two-digit.
That part was my opinion, not some broad consensus. Of course you'll find people fapping about stupid ideas everywhere just because they sound "cool" at a first glance. Look at the mountain of shitty kickstarters that promised the world, raised huge sums and ultimately ended up going bust, because "cool" doesn't necessarily translate into "viable".
The simulator community has you covered. And yeah, it works about as well as you can imagine (i.e. badly).
The rotors appear to be pretty tiny and are probably nowhere near large enough to generate significant lift in auto-rotation. That is assuming that the blades even feature adjustable blade pitch (which is needed to induce autorotation on a propeller designed for thrust).
Forget my earlier post, turns out the 777-300ER doesn't have enough range either way.