When did inflight smoking become (widely) prohibited?

There is an interesting timeline here which includes other transportation service as well.

According to this New York Times article, the FAA banned smoking on all flights under 2 hours beginning April 23, 1988. According to the timeline, Northwest and British Airways make all domestic service smoke free shortly after.

On February 25th, 1990, the rule is expanded to all domestic flights under 6 hours, which includes all but 28 of 16,000 flights.

In 1992, ICAO urges its members to go smoke free by July 1, 1996. Delta went smoke free on all flights starting in 1995. TWA, United, and American follow suit in 1997. In 1998 even more airlines go smoke free.

This federal rule bans smoking on all flights to and from the US and is effective June 4, 2000. It mentions that all domestic and 98% of international flights were already in compliance.

td;dr The FAA banned smoking on all flights under 2 hours in 1988, and it escalated from there. Within 10 years, almost all airlines were smoke free.

I think that smoking had the advantage of being a health issue, whereas electronic devices are more just convenience and comfort. Barring any emergent safety issues, it seems easier to allow people to do something new (use electronic devices) than stop them from doing something (smoking). Considering the proliferation and advancement of inflight entertainment systems, I would expect airlines to be fairly quick about allowing the use of devices, especially since some already do (I know American and United do).


It happens because of a compressibility error in the airspeed indicator (yes, even in the digital ones, since the error is not mechanical, but a physical property of the air).

As you might be aware, the speed indicated on your instruments is not really a speed at all, it is actually a pressure. Your pitot measures a deltaP between static and pitot and displays that pressure difference on a scale noted in knots.. we call that Indicated Airspeed.

This indication, because of changes of density, can be quite a bit different from your actual True Airspeed, but people didn’t care all that much about this difference, since the way the wing flies is reliant on that deltaP pressure difference anyway, so that you will actually stall at the same Indicated Airspeed, but not at same True Airspeed. (there is less density higher up but you are now traveling a bit faster, so the effect cancels out and the wing will behave the same)

The instrument was kept as it is in the cockpit (even though today we call it Calibrated Airspeed after a few changes) as a very usefull indication to the pilots.

Ok, now back to the question: turns out when planes begun flying faster and faster, a second error, caused by compressibility appears, that makes the airspeed indicator over-read. The pitot pressure is reported higher than it should be because at high speeds the air compresses in the pitot and makes the pressure there artificially higher, the deltaP is higher, thus our Indicated Airspeed is higher. Of course, this pitot tube phenomenon is not happening on the wing, so now we have a problem: we have a high speed indicated at the instrument, but most of it is actually just compressed air. Our Equivalent Airspeed is in fact much lower. And the wing will in fact always stall at the same Equivalent Airspeed. That means your Indicated Stall Speed in the cockpit will be ever higher as you climb because of compressibility.

Now, instruments were still kept to display IAS instead of the EAS, and a provision has been made where the stall barber pole advances up as you climb to make up for compressibility error

Then why haven’t the instruments been changed to show EAS directly? That is a harder question to answer definitively. I suppose by now people were already too used to having IAS in the cockpit, and the error is only really a factor for jet planes flying above (say) + 20 000 feet at speeds above Mach 0.5.


Can a pilot use glasses to meet the FAA required 20/20 vision?

It can be with correction. And note that for third class, distant vision only has to be correctable to 20/40. The near vision standard is 20/40 for all classes. See https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/standards/

As @Pondlife notes, the operative words here are,  "with or without correction."


What alternative methods are there for controlling a plane when flight control surfaces have failed?

As far as I understand, the JAL123 pilots did use thrust manipulation in an attempt to control their crippled aircraft -- however, Japan's largely mountainous terrain conspired against them, as trying to figure out fly-by-thrust-lever requires a massive quantity of airspace, and unfortunately for JAL123, there was a mountain in the way of that effort.  UAL232 and OO-DLL, on the other hand, both happened over relatively flat terrain, which meant that the aircrews could concentrate on working with their crippled airplanes to get them back on the ground as safely as possible, without having to worry about terrain clearance.

Of course, the missing vertical stab didn't help them either, as it meant they had to do much more work to control their airplane.


Do contra-rotating propellers have the same RPM?

Most if not all contra-rotating propeller systems are geared together so that both sections turn at the same speed.  This is done so that as well as allowing effective conversion of very high power into thrust, torque and P-factor are cancelled, making the aircraft easier to fly (especially in a single-engine or two-into-one installation).

This is why you see the same diameter propeller in front as in the rear -- if they were turning at different rates, the slower one could be larger diameter (a limitation on diameter is transonic conditions at the tips) -- but you always see the same diameter on front and rear.


How does cost per seat-mile differ between commercial and private jets?

I did some basic math to figure it out in terms of current gas prices.  I got that a private jet is about 6x more expensive.  Keep in mind it is probably more in reality because these jets aren't being used as much as an airliner so the rental price will be higher as well as the fuel.  But like I said, this was just an estimate based on current fuel prices and performance of an airliner vs a private jet, to give you an idea of the cost difference.


How long should a boarding pass be preserved, after the trip? Is there any FAA mandate on the same to make any claims later?

If you have arrived approximately in time, picked-up your undamaged luggage, passed immigration and customs and doesn't want to use an airtrain (or something similiar) you should be able to safely discard it.

Personally I tend to keep them as holiday memory, so I miss the old style tickets/boarding-passes from the 90ies :)


Why did the speed of this plane drop so much?

At that point, altitude shows about 11 km, or FL330. Up there, 380 km/h, or 205 knots true corresponds to something like 124 knots indicated, well below clean stall speed.

This is ground speed though, so with very strong head-wind it could be possible. But the only sufficiently strong wind is the Jet stream and flying eastward they would have it in their backs.

Also for westbound flight, the dispatcher would have to make rather big mistake to send them across the jet stream—they do take forecast winds aloft into account when preparing the flight plan.

Data error is the only plausible explanation here.


Can I fly over Schengen zone without visa?

A visa is a permit to ask for permission to enter into a country by crossing its borders. Since you are not entering the country; but rather overflying it - you only need to worry about any requirements for your destination.

Now, if you are doing a technical stop, and you don't leave your aircraft - then you don't need a visa. This is true for normal passengers on commercial flights as well.

If you need to leave the aircraft, but not leave the sterile area of the airport - then depending on your nationality you may need a special crew visa (this is different than the normal visa you would get as a passenger).

For crew visas, there are no uniform rules. Each country is free to set their own permissions and requirements so you'll need to contact the embassy of the country you wish to stop in for information.

God forbid you face an emergency and have to land at a country and you don't have or don't know the visa requirements - there are provisions for such cases. Emergency permission can be provided to cross borders.

In all cases, make sure you carry a passport that is valid for at least 6 months after your return date.


Can a gas turbine be able to switch from torque to thrust?

The main way to convert a gas turbine to provide thrust rather than shaft horsepower is to attach a large fan or propeller in place of the previous load. For example, the GE CF6, which powers aircraft such as the 747, 767, and A330, has a gas turbine variant called the LM6000 that provides around 50 MW of power.

If you want to provide thrust from the exhaust, you're talking about a turbojet, which will require a lot of changes. A gas turbine like that in the CF6 is designed to extract most of the power out of the exhaust gas to drive a load such as a fan or a generator. Just removing that load is going to cause the engine to be unstable. Each stage in a turbine engine is dependent on the stages around it for smooth operation and even small changes can cause problems. You might be able to salvage the high speed spool but the rest will have to be redesigned to provide a stable compressor section and provide most of the thrust from exhaust.

Turbojets are very loud and only start to be an efficient choice at high speeds. Even modern fighter jets are powered by low-bypass turbofans.


How can I design and build an aeroplane from scratch?

Take the example of Ed Swearingen: He never went to engineering school, but spent years working with airplanes, gradually moving from handling to repair to improving them. In the end, he was a successful self-employed consultant who helped with a number of airplane designs and created some of his own designs, too.

So here is what I propose to do:

Hang out at a local airport (ideally one with lots of hardware passing through the local repair shops)
Don't shy from getting your hands dirty and from asking questions until you are satisfied with the answer.
Try to find experienced engineers and work closely with them.

Do that for 10 years and you will be hard to beat as an aircraft designer. If you happen to attend University in Germany, be sure to become a member of one of their Akafliegs - that is the best start into an aviation engineering education.

If you have already some idea how your design should look like, build it as a model first. Models can give you valuable lessons in aerodynamics and flight mechanics.


Can I use my non-WAAS GPS receiver with ADS-B in the United States?

In the USA, ADS-B requires a WAAS position source. A Garmin 530W can be used, but not a 530.

Here's a full list of FAA certified equipment needed for ADS-B. I hope that helps.


How can a plane be cheaply owned by multiple people?

what you describe could be called a flying club or shared ownership. These sorts of arrangements are common enough that you should be able to find a template for setting up one which contains the details of how maintenance and overhead are covered and how the club's finances must be recorded and reported.
The cost effectiveness and fairness are determined by how money flows into the partnership and how it flows out. I would suggest you look into the Experimental Airplane Association's documentation on airplane ownership.


How to locate the owner of a 5' styrofoam wing found in a field?

If it has a US registration number on it (N followed by 1-5 numbers or letters) you can search the FAA registration database to find out what aircraft has that particular registration number, and who owns it.
In the case of a 4-5 foot styrofoam wing this would likely only be useful if the aircraft in question was a registered UAV.

Some common sense needs to prevail here: Model aircraft often have an N number painted on them for decorative reasons, so if you look up N12345 and it says "That belongs to a Piper Cub" you can safely assume this wing does not belong to that particular real-world aircraft (as the Cub's wings are not made from styrofoam, and are more than 5 feet long).


Can I take friends flying with a private pilot glider license?

Glider PPL will suffice, did it yesterday and three or four times in the past three months.

That's me in the back seat preparing to take a co-worker for her first glider ride in a Grob-103:


Why don't passenger planes move back by their own means before taxiing?

I’m not exactly sure, but it sounds like you’re asking why planes need a tug on pushback. Some jet and prop planes such as the 727 and MD-80 can perform a power back where they start at the gate and use reverse thrust to exit it. This procedure was more common in the 70s and 80s but seems to have died out in the 2000s. According to wikipedia the practice was stopped to save fuel. Additionally, there was a high risk of foreign object debris entering the engines from the ramps. Thus, the procedure was even less common on low engine aircraft such as the 737. The C-17 performs powerbacks still for the armed forces, so size is not a limiting factor.

You can check out a video here of an MD-80 powerback.


Why do airlines not paint the wings on their livery? Why?

Some do. However, paint is expensive and heavy. You may find that getting approval to paint a lift producing surface is more difficult to justify to the regulatory authorities. And also, why paint somewhere you can't see very well when it adds weight and therefore burn more fuel?


How much drag do the gear doors create during retraction?

Of course gear doors create drag when open.  The question is "how much?"

As you suspect, door drag is not the critical factor here.  As usual the answer to your question is aircraft-specific, and your question is pointing to a generalized "old wive's tale" which is only true sometimes.

OK, what is the story behind the story?  Look at this Youtube video.  Watch the main gear as it enters/exits the storage wells in the fuselage.  The axles of the wheels are close to parallel to the direction of flight, which means the wheels are being dragged broadside in the slipstream.  A very high drag scenario which will affect aircraft performance.  The POH recommendation is (from memory, now) to climb over critical obstacles on takeoff with the gear down, and raise the gear only when the obstacle is cleared.  The attached video shows why.

This advice does not pertain to all planes.  Know your plane, read the POH.  Oh... and ask questions here!


How to avoid talking over others when using different send/receive frequencies?

In the specific case of a flight service receive-only frequency you will be able to hear other aircraft transmitting in that frequency (you still listen to your com radio, so treat the transmitting part just like any other transmission and wait for a break before you key the mic).

In the more general case when you have one controller (or Flight Service Specialist) working multiple frequencies you call in when the one you're transmitting on is quiet (and in the case where you're receiving Flight Service over a VOR wait for that to be quiet too).

The controller or FSS will answer you if they're free. If they're busy on another frequency or a landline they'll respond with "Aircraft calling, stand by" (or if they're really busy and don't hear you you won't get a response and you'll try again in a minute).
It's not a perfect system, but it works pretty well most of the time.


What is the ATC protocol for hijackings?

In the US, the ATC protocol for hijackings is classified for reasons of national security.

  10-2-6 Hijacked aircraft

  Hijack attempts or actual events are a matter of
  national security and require special handling. Policy
  and procedures for hijack situations are detailed in
  FAAO JO 7610.4, Special Operations.‡ FAAO
  JO 7610.4 describes reporting requirements, air crew
  procedures, air traffic procedures and escort or
  interceptor procedures for hijack situations

Air Traffic Organization Policy, FAA, 2015-12-10.

‡This document's content can only be accessed from within the FAA network.


Please explain differences between AFM and FCOM manuals?

The simple answer is that the AFM is a certification document whose content (procedures, limitations, and performance data) is fundamental to the airplane's certification requirements and is approved (both original and all revisions) by the regulating authority that certified the aircraft. You could say that the AFM is part of the airplane's type certificate.

The FCOM/AOM/Operating Data manual is just a company publication. Its content is not approved. It takes AFM procedures and expands them into a kind of company-recommended procedural framework, provides descriptive information, and provides non-certification related performance data used for planning, like cruise data, optimal profiles etc.


For a wing to be stable in its own right, its aerodynamic centre must remain static with changes in angle of attack. The usual approach is to sweep the wing and wash-out the outer section. Because your wing is unswept, you have only two choices in creating a stable aerofoil:

A symmetrical aerofoil, i.e. with zero camber.
A cambered aerofoil with reflex camber towards the trailing edge.

The first of these has poor low-speed characteristics and has really only seen use on aerobatic and early supersonic types.
The reflex type offers better low-speed characteristics, thanks to its positively cambered leading edge. RAF 34 provides a good example; it was developed in the 1920s when RAF 33, with even greater reflex, was found to have high drag. RAF 34 had much better performance above 200 kt and was used on several tailless types (usually swept and washed-out as well) such as the Westland Pterodactyls. It would be a good starting-point for your search.
But be aware that your tapered "plank" wing will have abysmal handling characteristics and a vicious, unrecoverable stall. Washout can help a little here, and the CG position will depend on this, as well of course as on your chosen aerofoil. Maybe using it as a hang-glider might be tenable, as the pendulum stability will mask the worst handling issues, but I would not want to take it up in case it stalled!
Addendum
Some remarks have touched on the NASA Prandtl-D experiments led by Albion Bowers, which owe much to Prandtl's "bell-shaped" lift distribution and Reimar Horten's exploitation of it in his flying wings. Prandtl's analysis applied principally to the straight wing and was not concerned with stability or yaw. By contrast the Horten/NASA implementation is applied exclusively to tailless swept flying wings, where stability and proverse yaw in the turn are essential to docile handling. In this latter context, many subtle variations of aerofoil across the span have been tried over the years. JW Dunne anticipated it all, and more, intuitively back in the pioneer era - the Science Museum archive contains boxfuls of his research models - but he was no mathematician. The precise relationships between the various design features and resultant flying characteristics still remain somewhat clouded and contentious, and Dunne's work studiously ignored, so some aspects of the original question here remain unanswerable. But one thing everybody I have mentioned has agreed on; if you do not sweep your wing then you are making life much harder for yourself.


Passenger hypoxia in a small plane at 11,000 feet: what is the pilot's responsibility?

There is no regulatory requirement for oxygen to be available for anyone on board an aircraft so long as it remains at altitudes of 12,500' MSL or less. And only the required minimum flight crew is required to have oxygen if they are flying above 12,500' up to and including 14,000 MSL' IF they will be at those altitudes for more than 30 minutes. CFR 91.211  If they were going above 15,000' MSL that would be another story.
So the short of it is, No, that pilot was not irresponsible, perhaps, maybe slightly inconsiderate, but not irresponsible.

The reason for this is the lower density of the air isn't low enough to harm the majority of passengers.  Except for extreme cases, such as those with severe and uncontrolled asthma or heavy smokers, the worst thing that would happen would be the passengers would just get sleepy and fall asleep.  This is natural, and because the body does not need as much oxygen when asleep.  For passengers there generally won't be any harm done from a mild case altitude induced hypoxic hypoxia.

And YES! You can ask someone if they will be 'OK' at higher altitudes!  Just as it is not only 'OK' but required to ask their weight for weight and balance calculations. (And quite frankly I believe most people find that more intrusive.)
In fact you should take 5 minutes to tell your passengers that the flight will be in excess of, say 11,000', that way they can be prepared for some unusual effects and not have to worry about them.  To take it a step further, remember you are the Pilot in Command and you should be aware of your passenger's limitations as that may trigger any self imposed safety limitations you have for the safety of the flight.

Now, if you just want passengers to be comfortable and/or they absolutely insist on not taking a little nap, then it is entirely up to you if you want to carry a portable aviation oxygen canister with you for your passengers.

For further information on hypoxia I would recommend the FAA's page on it and the differing effects on pilots, and by extension passengers.

Hope this helps!


How do ATCs choose between Tower, Approach, and Enroute facilities?

The initial assignment has been made when you're hired, and you'll be sent to either Enroute or Terminal training. The split there occurs as they're hiring to fill a class, or just sending out names to facilities to pick from, or some other factor that they keep changing. The terminal option I believe they'll say class x will get to choose between the following facilities in order of how well they did in class.  (How facilities get assigned is changed a lot, and I'm not positive how they're currently assigned).

If you go to a tower or a Tower/Tracon(up/down facility), then you'll go to the academy for the tower initial class. If you get assigned to a TRACON, you'll go to a tracon dedicated class. Enroute goes to an Enroute class. Each has their own lengths. If you're at an Tower/TRACON combined facility, you'll go through the Tower course in Oklahoma, and then go to your facility and get trained in the tower, once done there, you'll then be sent to Oklahoma again for the Radar course, and return to your facility for training in the TRACON.

A career in the US ATC system is generally what you make it. Enroute people generally stay at their centers, they don't move facilities as much, mainly as they're at the upper level facilities and at the top of the pay levels. People in the terminal environment move a lot more. In the past to move to the highest level towers, they often wanted to see a radar certification, or some other way to differentiate candidates. But things have changed recently, and I'm not sure how they're picking candidates fully now. Also you can changed tracks, from Terminal to Enroute or vice versa, but it's generally a less common move.


What are the main components of the Airbus fly-by-wire system? Is ECAM related to FBW?

ECAM and FBW are not directly related, but information and alerts regarding the flight control computers and actuators are displayed on the ECAM screens, like any other information not visible on the primary flight display or the navigation display.

Fly-by-wire

The fly-by-wire concept is actually simple:

In traditional aircraft, the control surfaces like ailerons or elevators are linked to the control inputs used by the pilot, e.g. the column. This link can be direct (cable) and/or amplified (hydraulic or electric actuator commanded by the pilot).

In "FBW" aircraft, the control inputs are instead sent to calculators which deliver actual orders to actuators. Each FWB system, in addition to introducing calculators into the pilot-control surface chains, also gets information from sensors to measure the aircraft response to orders (feedback).

This design has two advantages:

There is an actuator (e.g. an hydraulic jack), so the pilot (or the autopilot) has to exert on the control inputs only a fraction of the actual force that needs to be exerted by the actuators on the control surfaces.
More important for the concept, the calculator can supervise the pilot commands, so that the aircraft is never put in unwanted or dangerous configuration, e.g. stalled. This system is similar to the full authority digital engine control (FADEC) used for the engines.

The main calculators for Airbus A320 family are:

ELAC: elevator and aileron computer
SEC: spoiler and elevator computer
FAC:  flight augmentation computer
SFCC: secondary flight control computer

They are redundant and some functions dedicated to one computer can also be executed on other computers.

Source: Fly By Wire Systems Explained

Actuators are moved using a transfer function from pilot input. In simple words, some correspondence links the actuator deflection to the pilot input. These correspondences are usually named "flight control laws". Airbus uses 3 laws:

Normal: When everything needed by the calculators is available. Maximum protection is available. Sidestick inputs by the pilot are converted into vertical G-load demand and lateral roll rate demand.
Alternate: When some calculators required data are not available. Some protections may be lost and sidestick lateral inputs are converted into a direct equivalence in control surface deflection angle.
Direct: When no protection can be provided by the calculators, due to calculator failure, missing input, actuator or control surface failure. Vertical and lateral sidestick inputs are directly converted into a proportional surface control deflection. Basically the aircraft is a non-FBW aircraft.

ECAM

In parallel instruments in general have evolved from gauges to electronic displays. The elimination of the third crew member (the flight engineer supervising engines, fuel and other parameters) has led to automatic supervision of aircraft parameters and filtering of displayed information.

By default, only a few parameters are shown to the crew, other are replaced by alerts when something is unusual or requires attention. The crew has also the possibility to display parameters/status on demand, e.g. the status of the cabin doors or the fuel tanks. The electronic centralised aircraft monitor (ECAM) is just such system which monitors and displays alerts and important parameters.

A319 ECAM after an actual electrical failure, source

The ECAM system includes two displays that can be configured by the crew:

Source

Relation between FBW and ECAM

Airbus FBW reconfigures laws when one of the flight control computers has failed. Because knowing this reconfiguration is vital for the crew and it follows some failures, this leads to alerts, information and suggestions being displayed on the ECAM screen. However this use of ECAM is not particular to flight control computers.

ECAM indication of autopilot being off, and laws being changed, source

For more technical information about this topic, see question: Is a Control Law Degradation in Airbus Planes displayed on the ECAM?


Why do some aircraft (e.g. Avro RJ85) have rear-mounted air brakes?

Location choice

Note: the BAe 146 / Avro does have wing spoilers.

Air brakes are in most cases mounted directly on the fuselage. Forward mounted air brakes would disrupt the airflow to the wings and engines, so the designers are left with three choices: above, under, or at the rear / on the sides.

Under, like on the Aero L-39, works well1 if the air brakes aren't big. Above is usually if all else fails, like on the F/A-18 Hornet and F-15.

Rear-mounted—inline with the center-of-mass—is the most convenient, aerodynamically and for maintenance. Like the Avro, F-16, or F-86.

Now, as to why the Avro—as most military jet aircraft and few jetliners—has it:

Lack of thrust reversal and steep approaches

The Avro RJ lacks thrust reversers "due to their perceived reduced effectiveness in anticipated conditions." The reduced effectiveness is because of the low landing speed and the closeness of the engines to each other on each side. Using reverse at low speed risks FOD ingestion and stalling of the nearby engine.

  It reasoned that since the
  146 would have a touchdown speed
  of only 90 kt, and because reversers
  are not normally used below about
  60 kt, their effectiveness would be
  limited. Reverse thrust also would
  have subjected each engine to an
  extra cycle/flight.

  Maximum descent rate achievable
  with the airbrakes is 7,000 ft/min and
  at speeds of less than 250 kt and below 10,000 ft, there is still 4,000 ft/min available. By comparison, a
  typical airliner descent rate on the
  approach is around 2,000 ft/min. BAe
  146 operators may also use airbrakes
  during the landing roll.

  (Flight, 1981)

One advantage that came out of having air brakes is the ability to fly steep approaches into airports like London City.

  [For] several years the BAe 146 was the only conventional jet aircraft capable of flying from London City Airport.

Thrust-to-weight ratio

Because of the Avro's high thrust-to-weight ratio, having air brakes deployed on approach makes it easier to control the speed. The thrust-to-weight ratio for the RJ100 is 0.28:1, compared to 0.16:1 for the comparable Boeing 717. It's even higher for the smaller RJ's.

Having a high thrust-to-weight ratio also allows operations from short runways and runways within cities, as the airplane can climb more steeply, thereby reducing the noise impact and also allows high payload.

(flickr.com)

Spoilers

  Air brakes differ from spoilers in that air brakes are designed to increase drag while making little change to lift, whereas spoilers reduce the lift-to-drag ratio and require a higher angle of attack to maintain lift, resulting in a higher stall speed.

The Avro still sports wing spoilers as shown above, those also help in braking as they transfer more weight to the wheels, and help reduce the likelihood of a bounced landing.

1 Belly-mounted air brakes on the L-39 help the pilot configure the plane for landing. Half-flaps + air brakes require the same trim/power as full-flaps and landing gear down (hence the under positioning). The pilot would use the air brakes to slow down, put down half the flaps, and trim the aircraft. The pilot can then on final approach put down the landing gear and full flaps, retract the air brakes, all without having to re-trim or change the engine power setting (which is narrow-ranged on the L-39).

Related: Why does this regional jet have its air brakes wide open before touchdown?


Are there any ducted propeller or fans without a shaft in the centre?

Perhaps an aeronautic version of one of the Voith maritime systems? This one appears to be electrically powered.
http://www.voith.com/en/products-services/power-transmission/voith-inline-thruster-voith-inline-propeller-11014.html (watch the "installation" video).
Also, this video explains the concept a bit (for maritime applications)

I suppose if you could arrange a lightweight frictionless magnetic ring bearing (possibly integrating electric drive), and/or peripheral drive linking system, it might be worth it if you needed to have two or three smaller fans beside each other, driven by a single core, rather than a singe large fan, in order to reduce fan/nacelle height. (imagine a B52 nacelle with one side shortened to just a fan cowling) I doubt that this would reduce overall drag, though, but I am intrigued by the concept of the greatest chord of the blades travelling the fastest.


What is the GE90-115b turbine power output in horsepower?

Based on the GE website, where they used a GE90-115B as a power generation unit, called the LM9000. GE cited 65,000 horsepower, which seems to scaled more reasonably when compared to the RB211 XWB
https://www.ge.com/news/reports/ge-oil-gas-just-turned-worlds-largest-jet-engine-65-megawatt-power-plant?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%253A%20gereports%252Ffeed%20%2528GE%20Reports%2529


What are the abilities and limits of a hexapod-based flight simulator?

What they can do.
Motion systems can produce accelerations that stimulate the acceleration sensors in our inner ear. Higher frequency acceleration can be sensed instantaneously in surge, sway and heave. From this answer:

  Motion systems can do a pretty good job at reproducing direct accelerations, until the actuator stroke runs out of course. So for short term accelerations.

This direct acceleration sensing is essential for pilot-in-the-loop motion control, that is why we have the sensors in the first place. The velocity information we get from our peripheral vision is an integrated signal and has 90° phase shift, causing a delay in sensing of motion.
What they cannot do.
Produce sustained accelerations. Six Degree of Freedom motion systems get by by tilting the sim, so that a component of gravity can be used for the feeling of sustained motion. But with some restraints on tilt velocity and angle, the tilt must happen imperceptibly and is of course also limited by the actuator stroke:

Imperceptively, by rotating at a rate below what the inner ear sensors can detect, and by not changing the visual image horizon.
Limited by stroke: in a 6-DoF system, using full tilt means that some of the other DoFs cannot be used. Full aft tilt has the front actuators fully extended, so linear surge cannot be actuated anymore.

Motion software contains a lot of fine balancing and frequency filtering code, to make optimal use of the available stroke and of the peculiarities of the inner ear acceleration sensors. Large stroke systems are essential for pilot-in-the-loop tasks in airliner and helicopter pilot training, and make the difference between being in an immersive simulated atmosphere, or being aware of the fact that you're inside some device firmly on the ground.


Why do narrowbodies have longer life than widebodies?

The author does a very good job explaining the jet market. The key take-away is that it's all about economics. In many ways, narrowbodies may "wear out" faster as they typically fly shorter routes and accumulate more cycles in a shorter period of time. Pressurization cycles are a big factor in structural fatigue.

But that's not the primary reason for retirements. Airplanes get retired when operating them is no longer profitable. Profit is generically income minus  costs. Income for aircraft is maximized by flying as much as possible (high utilization) with the highest load factors possible. Costs are primarily driven by capital depreciation, fuel, crew, and maintenance.

The shorter lifespan he identified for widebodies is driven by a few key factors:

Widebodies are a smaller percentage of the total fleet, so that even
a few "early" retirements will cause a larger shift in the average.
Widebodies are suited primarily for long-haul, high density routes.
So a shift in travel patterns can quickly leave a route
unprofitable. Covering that reduced demand will often mean shifting
to a smaller aircraft to keep the load factors up. Narrowbodies have
more inherent flexibility.
And what I would say is one of the most significant factors is the
shift of widebodies from 4 engines to 2 engines over the last 20-25
years. It's not a fast process as widebody construction is not very
high rate, but the cost benefit of 2 engine widebodies (B777, A330,
A350) means a lot of 4 engine aircraft (B747, A340) have been
retired in the last 10-15 years.


Why is A320's CG optimum position at 25% MAC?

I do not know much about the specifics of the A320 design, but I will try to come up with some general answers to your questions.

  So since CG and aerodynamic center at the same position, there would be no moment arm of lift, so what will be the use of tail plane?

Even if it was the case in the A320 that the CG and AC coincide (I do not know), it does not mean that there is no moment from lifting forces. The aerodynamic center is not the point of zero moment, it is the point of constant moment within reasonable angles of attack. Hence there will be a moment from the lifting force. Assuming CG and AC coincide, the moment generated by lift will not change the total moment on the aircraft. Therefore a stabilizer is still required.

  Also, as fuel burns, the CG shifts rearward, in that case aerodynamic
  center will be in front of center of gravity. wouldn't that mean
  center of gravity is behind the center of pressure?

Not necessarily. The center of pressure is usually for most angles of attack behind the aerodynamic center. Therefore, under the assumption that the CG and AC coincide, the CG can move aft of the AC and still be in front of the center of pressure.


Why is there such a large price difference between the A350 and B787?

Those prices are not the actual prices airlines pay for those planes. They get big discounts and more complex contractual terms. It's not like buying a box of pasta.
In conclusion, you can't assume that the price difference means a different cost of the components for the manufacturer


Do helicopters try to take off and land into the wind?

In general, helicopters require less power while flying forward (or backwards) compared to hover as translational lift (of Effective Translational Lift, ETL) is produced. Even though the blades are providing lift by rotation, the airspeed experienced by the blades is different if wind is present. For example, if there is headwind $v$, the advancing blades will have an airspeed of $r \omega + v$, while the retreating blade will have an airspeed of $r \omega - v$. As lift is proportional to square of airspeed, the implications are obvious.

For this reason, it is preferable to take off into the wind, rather than take off vertically.

Note that the power required is same for headwind or tailwind. However, tailwind landing (or takeoff) has some disadvantages from stability and power management point of view that is it generally discouraged, like:

In case of landing in tail wind, it is very difficult to abort landing and re-gain forward airspeed. Moving from negative speed to forward speed initially decreases the air speed the main rotor experiences, and the Power Curve shows an initial increase in Power Required. As the helicopter accelerates from negative (ground) speed, the main rotor system loses translational lift before it goes through zero airspeed. As a result, the power required increases, which requires increased pedal application and tail rotor power, precisely when the power requirement is high.
If there is a power failure, the chances of safe landing is reduced.
There is more risk of running out of directional control. In case there is a tailwind, the helicopter vertical tail (and fuselage) may align try to align with the wind, resulting in uncommanded yaw. If not corrected with proper pedal input, this may lead to loss of control.
In case of landing, the possibility of brownout or whiteout conditions is more in case of tailwind.


Where to find the aircraft maintenance manual for the Falcon 2000?

You can get the latest AMM through the Falcon Interactive Electronic Library by Dassault (FIELD). Contact the manufacturer through their website for pricing and information on how to setup an account.


Unless you're planning on trucking a seaplane out of where you have landed it, you usually don't need to worry about slowing down on landing since you can land in a far shorter distance than you can take off. In other words, the landing water run is far shorter than the takeoff water run.

If you do want to shorten the water run or reduce your taxi speed, holding up elevator will do that. A few seconds after touching the water and at idle power, you can use full up elevator without fear of the aircraft lifting off again, and it will add the drag of the elevator plus change the attitude of the floats or hull to a high-drag, plowing attitude. I used to do that if where I wanted to dock was aft of the touchdown point and I wanted to quickly slow to a safe turning speed.

Most constant speed props (variable pitch) on reciprocating engines don't have a reversible pitch or beta, but that can be purchased as a modification on some. The major use of such is as an aid in docking, and for that it's really useful.

Steering left and right repeatedly doesn't impress me as a very good idea, but I suppose it would help a little, but very little since it wouldn't be advisable to do it until you're well off the step.

Deploying the water rudder adds a little additional drag. Depending on the wind conditions, putting in a little rudder to match cross-controlled ailerons also adds drag, but that's not generally used to slow down as I remember. It is used, though, when sailing the aircraft, for which it's standard procedure.

See also Chapter 4 of the FAA Seaplane Handbook.


Were any composites used on the A340 series?

Yes!!

The slide shows that composite are used in rear pressure bulkhead and keel beam in addition to other parts.

Source: https://company.airbus.com/dam/assets/airbusgroup/int/en/investor-relations/documents/2008/presentations/GIF2008/gif2008_workshop_composites_hellard.pdf

You can read more:
http://www.lcc.mw.tum.de/fileadmin/w00bkg/www/PDF/Symposium/LCC_Symposium_Havar.pdf


Is there a standard on-board diagnostics protocol for FADEC aviation piston engines?

OBD systems were introduced by law in the 80s to reduce / control emissions, so it originated as a method to determine fault with emissions control systems. However, it was refined enough to monitor and control in real time engine and powertrains sytems in further iterations. Keep in mind that the OBDI / OBDII is a protocol that is run on the CANBUS network, which is important to remember that these two are separate entities  (CANBUS can run several different protocols, as Ron Beyer had stated). Other networks such as the LINbus for Audi/VW/BMW run different protocols but still work in a similar fashion.
From my military aircraft maintenance experience (from way back), our systems ran on the 1553 databus, which linked all systems together (nav, comms, AP/FD, etc) and is essentially the CANBUS equivalent. I believe Civil aircraft used the ARINC429 system, however I cannot confirm. For the protocol side, many aircraft (though mainly helicopters) use the Health Usage Monitoring System (HUMS), which provides the OBDII equivilant (more or less) to report back on engine condition, conditional maintenance, operation, etc.
So to make a short story long, there area a few standaridzed networks that aircraft use, however so far there is no standard protocol for all engines. Keep in mind that car manufacturers design and build the system as a whole in-house (chassis, powerplant and drivetrain), so it is not an issue to have all the systems integrate in a relatively simple manner), where airframes are generally designed by a company that will use a powerplant designed and built by a different manufacturer (or perhaps event the same airframe could have different engine variants from different companies), which makes standardization increasingly difficult.


What are possible causes for the flaps not deploying on a Cessna 172?

If the flap actuating motor is defective, you'll get exactly (or very close to) those symptoms, including the "interference" when the motor is operated. It could also be that the power connector to the motor was loose, damaged or corroded.


Why do farmers register their fields as airports?

Just spoke to the farmer that owns Graham Farms Airport (SN72), a grass strip in a cornfield near the sprawling metropolis of Harris, Kansas. Here it is on the sectional:

And Google Earth:

He has a Cessna 182 there. He told me he had it registered as an airport back in the 1970's, like Dave said, in case someone had an engine failure or something, atc could vector them there. He also occasionally allows people from nearby Garnett Municipal Airport (K68) to practice grass strip landings there.

He got an unexpected benefit from having it registered with the FAA several years back when the power company was planning to run a high tension line right across his landing strip. The power company refused to work with him on it so he called the FAA. Since it is officially an airport federal regulations forced them to run their line around it.

Aviation trumps power company profits!


Does Qantas have an above-average safety record?

Defining and Measuring 'Safety'

These ranking depends how you define safety. Here is your problem: You can easily do this by widely publicised facts, such as well documented fatal accidents. Fatal accidents occur much much too seldom to with any statistical confidence to say how safe an airline is.

What you would much rather do is go by accidents and incidents (the little things that occur everyday and give you a feeling for how stuff is done and handled). For instance: hydraulic leaks, loss of separation to other aircraft or electrical problems prompting a return. A small selection of these are reported on the popular site Aviation Herald, but this is (emphasis) only a small subset that happen to come through. Some western countries with the objectively the best safety are over-reported since they are just better at documenting. You'll find heaps of entries on 'fume events' on Airbus aircraft from Germany for instance.

These are considerably harder to collect, since how they are classified and reported changes by country and aviation agency. Some publish for common good, other ones barely collect them. For this reason, the way these 'rankings' do it is by fatal accidents and other easy to get parameters. This is eventually what comes through to newspaper sites with little detail on how they were put together.

The parameters measured by AirlineReports:

Is the airline IOSA certified?
Is the airline on the European Union (EU) Blacklist?
Has the airline maintained a fatality free record for the past 10 years?
Is the airline FAA endorsed?
Does the country of airline origin meet all 8 ICAO safety parameters?
Has the airline's fleet been grounded by the country's governing aviation safety authority due to safety concerns?
Does the airline operate only Russian built aircraft?

Most of these are bare minimums that can be expected from an airline, but do not really go to any distance to show who stands out. For any more detailed sense and purposes (how media are using it), I'd call this useless.

Also note that this does not include the liability question for fatal accidents- who was at fault? You can finally also (albeit unlikely) have a completely safe airline that does not have a single certification.

Qantas

Qantas has had two very serious incidents with a Boeing 747 and A380. They also had a serious incident on involving A330 losing altitude. This does not really IMHO award them as the 'safest airline' for the past few years, since this is considerably more than a lot of other airlines have experienced.

However, for all practical sense and purposes, they are as safe as any other airline. The chances of anything happening are just so incredibly remote that it's not worth the trouble of thinking about it. Getting a connecting flight to fly with another airline will probably be less safe than just flying them directly.

As for the maintenance matters, Qantas owns JetStar and they appear to use the same maintenance facility for their aircraft. A further difference is the training where there appear to be overlaps as well, so there are only small differences on perhaps the most important parameters differing the two.


Can aircraft other than rockets go to space?

Depends on what you mean.

Get to high altitude? Yes you can. It is really inefficient to get there, but some aircraft already do it.

Achieve a stable orbit and be able to maintain control? No, at those altitudes you do not have enough oxygen to keep your engines running, you have to bring your own (and thus use a rocket)

For the sake of clarity, some definitions:

reaction engine: includes both rockets and jets. The engine pushes some mass in one direction and by reaction it achieves thrust in the opposite one.
jet (engine): is used to refer to airbreathing engines. The aircraft carries the fuel, but not the oxidizer; that is taken from the surrounding atmosphere.
rocket (engine): is used to refer to non-airbreathing engines. The (space)craft carries both the fuel and the oxidizer. No atmosphere is needed.
space: above 100km of altitude.
go to space:

staying in space:

Images from xkcd


Can a plane land safely if it loses power during approach?

A standard “glide-slope” is 3–3.3°. 3° is 5.2% or 1:19, 3.3° is 5.8% or ~1:17.

A modern airliner will have lift to drag ratio between 17:1 and 20:1 in clean configuration and at best glide speed, which is usually somewhere in range 220–250 knots indicated, possibly even a bit more depending on weight. So it would be just barely able to follow the glide-slope if it was configured for best glide.

But on final approach it will at least need gear down and that increases the drag considerably. It will also already be slower than the best glide speed and have some flaps deployed and retracting them and accelerating to the best glide speed will take some altitude. Therefore if all engines quit on final, the aircraft is definitely landing short of the intended point.

For small aircraft I've read advice that if the runway is long enough, you should normally plan to use the middle part of the runway exactly so that you have a margin when engine quits on short final, accompanied with account of incident where it proved useful right there and another in the next chapter. However airliners need more runway, so they can't afford leaving much reserve on the near end, plus they usually follow the ILS or at least PAPI and those lead to fixed spot 1000 ft past threshold.


How dangerous would it be to take off at night with no ATC, no runway lighting system and have a single engine working?

I was wondering how dangerous it would be

When you preface a question with the above, you're asking for opinion, and when it comes to the details of what you ask, there will be widely differing opinions. That said, and in the context of the U.S., and if I understand your question (apologies if I'm misreading), the details of your question break down into three separate areas. One can come up with a number of possible scenarios which might combine those details, but let's use a concrete instance to better explain. I at one time was the company pilot for a firm that manufactured and maintained computerized sawmill equipment at mills throughout the west coast of the U.S. If one of our computerized systems broke down, we would fly to the mill as soon as possible. Some of these mills had private airfields alongside the mills or nearby. We could not reach ATC on the ground from any of them, and most had no runway lighting. Typically we would go into an airfield during the day, and often it would be dark by the time we completed repairs and left.

  no ATC

All night flights were done IFR. We would get an IFR clearance over the phone with a "void if not off by" time. So you takeoff, abiding by the clearance, and contact ATC on the assigned frequency as soon as you have enough altitude to reach them.

  take off at night when you have no runway lights

As long as you have landing lights and are familiar with an airfield, the lack of taxiway and runway lights is not a significant problem. What is a problem at remote runways is the possibility of animals (usually deer) on the runway, which is why we typically had at a car precede us down the runway while flashing their lights and honking.

  an engine failure (with a twin-engine) during take off at night

The twin engine aircraft we had available were a Cessna 310 and later a King Air A90. Unlike air carrier airplanes, continuing the takeoff if an engine failed during the takeoff roll was not an option, but the probability of that happening wasn't affected by time of day. Day or night, the only option was to abort. We were no more exposed during the night than during the day in that respect.

If an engine failure happened after takeoff, day or night, you would handle it in the same way. Fortunately, we were operating out of airfields where our departure path wouldn't need to be altered due to the reduced single-engine climb rate.

We had a single-engine Cessna Turbo 210 available as well. During the time that was our primary aircraft, we had no qualms about single-engine night or IFR operations. Many may disagree with such. However, although as I remember Part 135 of the FAA regs does not allow single-engine night or IFR, Part 91 does (or at least did) and I never personally knew anyone who had problems while doing so. Obviously there is some additional risk, but we considered that acceptable.


Can I get a FAA medical certificate and apply in an Indian airline?

Well Air India is hiring qualified pilots here. The advertisement says you need a medical certificate issued by the DGCA. There is no mention of accepting an FAA certificate.

I'm not completely sure how it works in India but usually you need to get a medical certificate from the country in which the airline is based (or to be specific, the country in which the aircraft is registered). I'm not aware of any exceptions to this rule except for temporary operations, but I stand to be corrected.


Why does the bottom part of an aircraft nose curve upwards?

Having the tip of the nose in the centre gives best combination of aerodynamic performance, weight and internal volume. If you move the tip down, the slope above it will either be steeper, leading to higher drag, or longer, leading to greater length and thus weight; or you don't extend the plane, but then the longer sloped part will provide less internal volume. Only the cockpit windows, which need to be on the sloping part, shift the nose a bit down, to the centre of the cross-section just before cockpit.

Cars are different. For a car you want the bottom surface flat, because you don't want to push and compress air in the gap between the vehicle and the ground. But aircraft has air all around and it is most efficient for it to push air equally to all sides, so a circularly symmetrical shape works best.

Also note that lift is yet another thing. Lift requires a sharp, downward-sloped trailing edge.


What effect does cold weather have on helicopter performance?

Cold weather definitely affects the performance of helicopters (as it does all aircraft), because it affects the density of the air they move through.

I will ignore icing so let's assume dry air.

The lift equation is:

$$ L = \frac{1}{2} \rho V^2 S C_L $$

$L$ = Lift

$\rho$ = density of the air.
$V$ = velocity of the aerofoil (rotor)
$S$ = the wing area of the rotor
$C_L$ = Coefficient of lift , which is determined by the type of rotor and angle of attack.

As you can see, lift is proportional to the density of the air and since density at any given altitude is inversely proportional to the temperature, the colder the air, the more dense it is.  So, for a given rotor, spinning at a given speed at a given altitude, the colder the air, the more lift is produced.

Engines also operate more efficiently when the air is colder since the density is higher and the charge of air/fuel introduced into the engine is greater. (See here for more information.
 Of course, this does not apply to your RCH apart from some effects on the efficiency of the batteries and motors (which may perform more poorly at lower temperatures).

So in general, the colder it is, the higher the performance.  In most helicopters, the difference in performance on a cold, dry winter day is very noticeable and much better than on a humid, hot summer day.

It's also worth understanding the properties of air.  The colder the air, the lower the dewpoint so the less moisture it can contain.  Moisture in the air also lowers peformance.

The problems you encountered with your RC model aren't problems with helicopters in general.

Colder weather does not make you more susceptible to vortex ring state (aside from some minor side effects): You would still only descend into the vortex if you did not pilot the helicopter correctly. (Note that you cannot enter vortex ring state with the rotors stopped since they are not producing a vortex.  Also note that on a real helicopter, if the rotors ever stop, they will not start again no matter what you do.)

BTW, I'm being pedantic, but helicopters do not have propellors.  Technically, they are the same thing, but asking a helicopter pilot about the propellor annoys them, even if they don't show it.  It's as bad a calling a helicopter a "chopper".  Only Arnie and Chuck get to call helicopters "choppers".  And that's only because helicopter pilots are universally weedy and would get stomped by Arnie or Chuck if they argued.


How does the FAA decide whether an aircraft is deemed a helicopter?

The definition of a helicopter as well as other aircrafts is provided in 14 CFR Part 1

http://www.ecfr.gov/cgi-bin/text-idx?SID=8403e178a4e1d0f8339151fe2529e600&node=14:1.0.1.1.1&rgn=div5

Manufacturers may seek clarification from the FAA about these definitions if/when there is a requirement .


Why are the leading edges of wings not always made as 'sharp' as possible?

A blunter (less sharp) leading edge allows the wing to operate effectively for a wider range of angles of attack (AoA). The angle of attack is the angle between the approaching airflow and the chord line (as illustrated below)

As you can see, the air has to curve around the leading edge on the upper side of the airfoil. This curvature accelerates the flow and thus creates an area of reduced pressure and thus contributes to the lift of the airfoil.

A sharper leading edge will cause a more intense curvature of the flow and therefore reduce the local pressure even further.
A higher angle of attack will also cause a more intense curvature of the flow with the same effects.

Here's the problem: In order to reach pressure equality between the upper and lower side at the trailing edge of the wing, the pressure will have to increase again as you move further towards the trailing edge.
The boundary layer of the flow doesn't like this at all. Strong pressure gradients will cause the boundary layer detach (generally, the boundary layer is already turbulent for commercial aircraft). A detached boundary layer (stall) causes a drastic increase in drag and decrease in lift and is therefore highly undesirable.

To increase the range of angles of attack at wich the boundary layer stays attached and to allow for a more gradual transition between normal flow and stall, the designers favour a quite blunt leading edge for most commercial and general aviation aircraft. This will increase the drag at zero AoA, but won't force the air to follow a high curvature at positive AoAs.

Supersonic aircraft such as the Concorde and fighter aircraft have to deal with a new type of drag called wave drag. Generally wave drag can be reduced by having sharp leading edges.
Most boats also have to fight against some kind of wave drag (although the fluid dynamics are very different) and therefore also have sharp hulls.

This is a broad generalisation and there are a lot more things to consider in reality. If you want I can go into more detail.


Why is the Piper PA-23 considered a bush-plane, while the Beech 95 Travel Air is not?

Without getting into the details of the two, there are going to be 3 factors:

Landing Gear suitable for rough fields.
Decent size cargo loading doors and cabin with cargo provisions.
Power to weight ratio suitable for short rough fields.

Neither of those airplanes are really purpose-built for bush operations, but to the extent they have those characteristics they could be said to be more or less suitable.

When the US Army was looking at the DeHavilland Canada Beaver, which WAS specifically designed for bush operations, being designed in response to an operator survey, there was a hue and cry from the US aviation lobby, prompting the Army to have a fly-off with the Beaver vs a motley assortment of "utility" aircraft put forward in haste by various manufacturers (including the Travel Air IIRC, and the Cessna 195).  The Beaver won without much difficulty, and the US Army went on to take nearly 2/3rds of Beaver production.


Retreating Blade Stall, P-Factor, and Gyroscopic Precession

Related, especially footnote 2: What is the influence of yaw on P-factor?
The answer to your specific question is that when you are talking about the effect of P-factor on a prop, you aren't talking about actually moving the prop disk in pitch or yaw.  You are applying a rudder force as needed to prevent that movement, so there's no gyroscopic effect to consider.
Whenever the prop disk is actually pitching or yawing-- regardless of whether the cause of the movement is P-factor or something else-- then you have to consider the gyroscopic effect, which makes the force act as if it is applied to the blade disk at a point 90 degrees further along in the direction of rotation.
In helicopters, the individual blades can be moving in a way that creates the same gyroscopic effect as pitching or rolling the entire blade disk, even when the blade disk as a whole is not pitching or rolling.  This is due to the way the blade is hinged.  This wouldn't happen with a rigid rotor disk.  So that's why-- at least with a hinged blade system-- the P-factor effect acts 90 degrees further along in the direction of rotation from the point where it is actually applied, even when the body of the helicopter isn't pitching or rolling, and even when the circular path traced by any given rotor blade tip is remaining constant over time.


What aerodynamics forces are acting on a jet fighter during slow flight demonstration?

break down my understanding of the forces that specifically oppose gravity.

There are no separate forces that oppose specific other forces. There is simply a set of forces and they all add up and the sum divided by the inertial mass of the plane equals acceleration.

Gravity always points down, so to prevent downward acceleration, the sum of the other forces must point up. But whatever force points up can do that.

  Is my understanding accurate?

Mostly yes. Thrust always points forward along the engine axis, so if the engine axis points up, so does thrust.

  Is there a good, well known reference to aerodynamics that does not gloss over the entire gamut of forces involved during a wide range of flight situations?

There is really just a few forces, always:

The airfoils produce force that is approximately perpendicular to them. It grows with angle of attack (angle between the airfoil and the air flow) with one peak at the at the stall angle of attack (usually 10–15°) and another at 90°.

This force is normally described as two components, lift, which is perpendicular to the air flow, and drag, that is parallel to it. That means the second maximum of lift is at 45°, because at 90° the force is parallel to the flow and thus all drag.
Form (parasite) drag. This is parallel to the flow.
Thrust. This is always approximately forward along the engine axis.
Weight. This always points down. It is actually composed of gravity, which points towards the centre of Earth, and small contribution of centrifugal force that points away from the Earth axis of rotation, but that's just nitpicking.

And then you just need to do vector addition.

So when the aircraft flies with high angle of attack, the thrust points diagonally up, cancelling some of the weight, while the force on the wing is tilted aft, cancelling the other part of weight, but also causing huge drag, so the thrust needs to be correspondingly large. That's why only fighters and aerobatic aircraft with their large thrust/weight ratios can do this kind of stunt.

For more details I would suggest See How It Flies by John S. Denker. It covers basic aerodynamics and explains reasons behind common piloting techniques. Chapter 4 discusses the forces.


Why is UTC activation time referred to 30W in NAT-OTS?

Think of 30W as a kind of traffic marker for flight planning.
If your planned route is going to cross 30W before the tracks activate (that is, ahead of the traffic flow), then you can file "random route." If you're crossing 30W during the active period, then you have to file on one of the tracks unless you can climb above them before crossing the entry fix.
This also works going against the flow: if you're crossing 30W in the opposite direction during the active period, you'll have to route either north or south of the tracks unless you can get above the NAT FL's before your entry fix.
As far as Zulu goes, it's just the common reference everyone uses (therefore, "Universal Coordinated Time").


How high can I fly a kite above my farm?

It depends how big the balloon or kite is. Balloons and kites are governed by 14 CFR 101, but specific regulations only apply above a certain size. 101.1 says:

  a) This part prescribes rules governing the operation in the United
  States, of the following:

  (1) Except as provided for in §101.7, any balloon that is moored to
  the surface of the earth or an object thereon and that has a diameter
  of more than 6 feet or a gas capacity of more than 115 cubic feet.

  (2) Except as provided for in §101.7, any kite that weighs more than 5
  pounds and is intended to be flown at the end of a rope or cable.

However, note the reference to 101.7, which says (in part):

  No person may operate any moored balloon, kite, amateur rocket, or
  unmanned free balloon in a manner that creates a hazard to other
  persons, or their property.

That means, if your balloon or kite is too small to be governed by part 101 then there are no specific restrictions on how you operate it, but you still can't fly it in a way that puts other people in danger.

If part 101 does apply to you, then you have to follow the rules in 101.13 and 101.15:

  §101.13   Operating limitations. (a) Except as provided in paragraph (b) of this section, no person may operate a moored balloon
  or kite—

  (1) Less than 500 feet from the base of any cloud;

  (2) More than 500 feet above the surface of the earth;

  (3) From an area where the ground visibility is less than three miles;
  or

  (4) Within five miles of the boundary of any airport.

  (b) Paragraph (a) of this section does not apply to the operation of a
  balloon or kite below the top of any structure and within 250 feet of
  it, if that shielded operation does not obscure any lighting on the
  structure.

  §101.15   Notice requirements. No person may operate an unshielded moored balloon or kite more than 150 feet above the surface of the
  earth unless, at least 24 hours before beginning the operation, he
  gives the following information to the FAA ATC facility that is
  nearest to the place of intended operation: [contact details, time, altitude etc.]

There are more requirements in 101.17 and 101.19.


Is there any non-experimental way to obtain CL, CD, and CM as a function of the angle of attack and the control surface deflection angle?

The graphs in the OP show fairly typical results that one would expect from linear analyses (e.g. VLM).

1. Lift

In the linear range, the lifting surface's lift coefficient ($C_L$) can be expressed as:

$$C_L = a_0 \alpha + a_1 \delta$$

where $a_0=\frac{\partial{C_L}}{\partial{\alpha}}$ is the lift curve slope and $a_1=\frac{\partial{C_L}}{\partial{\delta}}$ is the lift slope per plain-flap deflection, which are constants in the linear range and can be readily seen in your lift plot.

Conclusion: You can simplify your lookup tables to the above equations (all constants) if you are only interested in capturing the linear effect (which is all that VLM can capture anyway).

2. Pitching moment

In the linear range, you can express the pitching moment coefficient ($C_m$), which I assume is computed at quarter chord, as:

$$C_{m} = C_{m_{ac}}(\delta) + C_L\frac{l_{ac}(\delta)}{\overline{c}}$$

where $C_{m_{ac}}$ is the pitching moment at the surface's aerodynamic centre (AC) and is a function of $\delta$; $l_{ac}$ is the distance between the 1/4c and AC and is also a function of $\delta$; $\overline{c}$ is the reference chord length.

The $C_m$ plots you've shown seems to line up very close to the aerodynamic centre of the lifting surface (by the fact that there is very little change in  $C_m$ with respect to AOA). Flap deflection only significantly changes the offset ($C_{m_{ac}}$). The variations in the slopes are because you do not have a full span plain-flap (you have elevons which are partial span), which changes the spanwise lift distribution and the resulting aerodynamic centre.

Conclusion: You can replace your multi-dimensional lookup table to two 1-dim tables for $C_{m_{ac}}$ and $l_{ac}$, and supplant with the above equation. You may even replace these lookup tables with constant linear relationships if your plots hold water.

3. Drag

The drag coefficient ($C_D$) is the most interesting. It seems like there is some boundary layer analysis combined with the VLM, since $C_{D_0}$ changes per flap. If the Reynolds number do not change significantly, you can attempt the following simplication:

$$C_D = C_{D_0}(\delta) + K(\delta)C_L^2$$

where C_{D_0} is the form drag and $K$ is the induced drag factor, both of which are a function of $\delta$.

Conclusion: You may again simplify your multi-dim lookup tables to two 1-dim tables.

4. Lastly...

You definitely will start to see nonlinear effects at 30 deg control deflection in real life, maybe even at 20 deg. This is obviously not captured by VLM.


What is the tail strike pitch angle of the ATR-72?

The FCOM says "tail strike may occur if pitch attitude exceed 8° during the flare
depending upon vertical speed at touch down" (Ctrl + F "tail", matches 31 and 32).


Can airliners land with auto pilot in gusty wind conditions?

To the first part of your question, the airplane is not moving BECAUSE his yoke movements are "strong and fast". Experienced pilots can feel a gust and respond with a control input to counter it before it has enough time to affect the aircraft. (You really can't appreciate this from a camera fixed to the airframe.)  As mentioned in a comment, this is called "staying ahead of the airplane" or "flying by the seat of your pants". Quick and correct reactions are required to keep the approach on track when being buffeted around.
Another thing that is worth pointing out is that the magnitude of control inputs is higher at slower approach speeds because of the reduced effectiveness of the control surfaces. You wouldn't want to move the controls that much at cruise speed. Just like when driving on a bumpy road you move the steering wheel a lot more than when cruising on the freeway.
I have never flown an airplane with auto-land capability, so I cannot answer the second part. However, given the experience I do have with a couple different autopilots, my belief is that even the best systems would be stressed trying to keep up while landing in very gusty conditions. There are just some things you still need a trained and experienced human for...


Can you legally obtain Boeing maintenance documents?

Everything is available for a price, and you don't need Google's help: You can get the Boeing Maintenance Performance Toolbox right from Boeing if you contact them.

You can also Google around and get PDFs of Boeing maintenance documents but these would be from unofficial/unauthorized sources (at least one Boeing maintenance manual made it onto Wikileaks).

As Boeing likely holds a copyright on their maintenance documents obtaining them from an unofficial/unauthorized source would be an infringement on that copyright.
More importantly you can't guarantee documents from an unofficial source are correct, current, and unmodified. If you intend to use the document for any aviation purposes (like performing maintenance on an aircraft) you would want to be absolutely certain they are the latest approved revision from Boeing.


What is meant by "Control your descent with throttle when landing, not with pitch"

Your pitch is adjusted to maintain airspeed, whereas throttle and thrust are used to establish a rate of descent.

Shameless steal from KeithS comment below:

  [Y]ou're gliding down to the runway, but you need a little engine power to keep a shallow glide slope because you aren't in an actual glider. The real explanation is that trying to use pitch to control glide slope causes dramatic changes in angle of attack, especially at the lower speeds used for approach and landing. This could cause a stall, or a severe loss of altitude. The throttle provides much more minute control over your angle of attack and thus your glide slope.


To get to the bottom of it, it might help to look at lift at a molecular level:
Every air molecule is in a dynamic equilibrium between inertial, pressure and viscous effects:

Inertial means that the mass of the particle wants to travel on as before and needs force to be convinced otherwise.
Pressure means that air particles oscillate all the time and bounce into other air particles. The more bouncing, the more force they exert on their surroundings.
Viscosity means that air molecules, because of this oscillation, tend to assume the speed and direction of their neighbors.

Flow over the upper side of the wing
Now to the airflow: When a wing approaches at subsonic speed, the low pressure area over its upper surface will suck in air ahead of it. See it this way: Above and downstream of a packet of air we have less bouncing of molecules (= less pressure), and now the undiminished bouncing of the air below and upstream of that packet will push its air molecules upwards and towards that wing. The packet of air will rise and accelerate towards the wing and be sucked into that low pressure area. Due to the acceleration, the packet will be stretched lengthwise and its pressure drops in sync with it picking up speed. Spreading happens in flow direction - the packet is distorted and stretched lengthwise, but contracts in the direction orthogonally to the flow. This contraction is needed to make space for that wing; in supersonic flow it will decelerate for the same purpose. Once there, it will "see" that the wing below it curves away from its path of travel, and if that path would remain unchanged, a vacuum between the wing and our packet of air would form. Reluctantly, the packet will change course and follow the wing's contour. This requires even lower pressure, to make the molecules change their direction. This fast-flowing, low-pressure air will in turn suck in new air ahead and below of it, will go on to decelerate and regain its old pressure over the rear half of the wing, and will flow off with its new flow direction.
Note that lift can only happen if the upper contour of the wing will slope downwards and away from the initial path of the air flowing around the wing's leading edge. This could either be camber or angle of attack - both will have the same effect. Since camber allows for a gradual change of the contour, it is more efficient than angle of attack.
Flow over the lower side of the wing
A packet of air which ends up below the wing will experience less uplift and acceleration, and in the convex part of highly cambered airfoils it will experience a compression. It also has to change its flow path, because the cambered and/or inclined wing will push the air below it downwards, creating more pressure and more bouncing from above for our packet below the wing. When both packets arrive at the trailing edge, they will have picked up some downward speed.

Behind the wing, both packets will continue along their downward path for a while due to inertia and push other air below them down and sideways. Above them, this air, having been pushed sideways before, will now fill the space above our two packets. Macroscopically, this looks like two big vortices. But the air in these vortices cannot act on the wing anymore, so it will not affect drag or lift. See here for more on that effect, including pretty pictures.
Lift can be explained in several, equivalent ways
Following the picture of a pressure field outlined above, lift is the difference of pressure between upper and lower surface of the wing. The molecules will bounce against the wing skin more at the lower side than at the upper side, and the difference is lift.
Or you look at the macroscopic picture: A certain mass of air has been accelerated downwards by the wing, and this required a force to act on that air. This force is what keeps the aircraft up in the air: Lift.
If you look at the wing as a black box and only pay attention to the impulse of the inflowing and outflowing air, the wing will change the impulse by adding a downward component. The reaction force of this impulse change is lift.
Either way, you will arrive at the same result. By the way: Most of the directional change happens in the forward part of the airfoil, not at the trailing edge!

Lift is a matter of definition
Lift and induced drag are both part of the pressures acting on the wing. If you add up all the pressure forces acting on a wing, their resulting vector will point slightly backwards. The streamwise component is drag, and the component orthogonal to the direction of movement is lift. This is just a defininion, made for simplicity.


How dangerous was this approach of a Dash8 Q400 really?

The relevant TAF that the pilot would have seen before going there is below (only showing the bits for the time of landing):

  TAF AMD EDDL 180929Z 1809/1912 22025G40KT 9999 SCT035
  TEMPO 1809/1813 26035G50KT
  PROB30 TEMPO 1809/1813 26045G65KT SHRAGS BKN015CB

So the pilot was aware of a strong cross wind possiblity, but even 26065KT is 27 kt crosswind (runway is 233) which is within the limits of the plane. So there was no reason to divert before getting there.

The metars just before and after the landing are below:

  METAR EDDL 181050Z 27045KT 9999 SCT037 BKN043 08/00 Q0993 TEMPO 27045G55KT=
  METAR EDDL 181120Z 27034G48KT 9999 -RA SCT028 BKN038 07/01 Q0995 TEMPO 27045G55KT=

So the "baseline" was 27045KT, i.e. 27KT crosswind, and the maximum gust wind was 27055KT, or 33kts crosswind, just 1 kt above the plane limit.

Note that the metar wind indications are rounded to the closest 10 degrees, so the worst case could have been a wind from 274 degrees gusting at 55 kts, or 36 kts crosswind.

We can assume that the pilot decided to continue the approach based on the wind information provided by the tower.

Whether the pilot should have aborted at the last second because the landing was not going as planned is hard to gauge on a video, but based on the information we have, the wind parameters were ok.


You have almost solved the problem yourself. The website you linked to does not help you because, for some reason, it assumes Local Mean Time (LMT) to be equal to UTC. For your problem, LMT needs to be for 85° of East longitude. So, ignore that website and let's move on.

For every degree of longitude, you calculate 4 minutes of difference from UTC. You have already correctly calculated the LMT difference from UTC for 85°E:

  First of all, what I've done is converting longitude into time as
  follows: $$t=85\cdot4=340\hspace{1mm} min=5h\hspace{1mm}40m$$

This leaves you with the question of whether to add or subtract this difference, as you stated:

  But then, in order to compute the UTC time, what do I have to do, either adding up this time to the current LMT or subtract it (and what is the reason)?

Let me start with the reason—the explanation of why we want to either add or subtract the difference between LMT and UTC—and then give you the solution.

LMT can be thought of as roughly equivalent to time based on the Sun's position. It is not equivalent to that, which is Solar Time, but it is related. Keeping that approximation in mind, consider the difference in time between when the sun reaches solar noon over Delhi, and when the sun reaches solar noon over London. As the earth rotates, the sun reaches solar noon first over Delhi, and then, a few hours later, over London. Thus you know that UTC will be a few hours behind Delhi LMT. This means that you need to subtract the calculated difference between LMT and UTC.

Another way to put this is: LMT for East longitude is ahead of UTC (subtract the difference to find UTC), and LMT for West longitude is behind UTC (add the difference to find UTC). Thus a more proper way to perform your calculation mathematically would be to properly incorporate the negative sign:

$$t=-85\cdot4=-340\hspace{1mm} min=-5h\hspace{1mm}40m$$

Therefore, if the LMT in Delhi (LON=85°E) is 17:45, then:

$$UTC=12h05m$$


What is the procedure to turn a certified aircraft into an experimental aircraft?

You essentially convert it to Experimental Exhibition, not Experimental Amateur-Built. That means more restrictions, depending on the FSDO. For instance, your operating limitations may prohibit passengers, or require permission for every flight over a given distance.

It is said that the FAA can be sensitive to people trying to put type-certificated aircraft into Experimental category for recreational use. Important advice below is that you should get permission from the FSDO before starting work on the airplane.

Even if you do this (and they likely won't like you converting say a Cherokee or a Cessna 172 to experimental), they will place certain restrictions on use, such as only flying within a 25 mile radius, and every year you may have to submit a "Program Letter" with a list of all the fly-ins and shows you are going to go to (since it is experimental-exhibition category, so you need to exhibit it!)

All that is to say, you probably will have a hard time converting a certificated plane to experimental and using it like it seems you intend to from your question.

Here is the relevant section from FAA Order 8130.2H.

  Section 10. Certification and Operation of Aircraft Under the
  Experimental Purpose of Exhibition or Air Racing

  General. Under the provisions of § 21.191(d), exhibition aircraft are defined as aircraft that exhibit the aircraft’s flight
  capabilities, performance, or unusual characteristics at air shows,
  fly-ins, and aviation events; for motion picture, television, and
  similar productions; and for the maintenance of exhibition flight
  proficiency, including (for persons exhibiting aircraft) flying to and
  from such events and productions. Under the provisions of § 21.191(e),
  air racing aircraft are defined as aircraft that participate in air
  races, including (for such participants) practicing for such air races
  and flying to and from racing events.

  a. Exhibition. A certificate for
  experimental exhibition must only be issued when an aircraft is to be
  used for valid exhibition purposes. Included in those purposes are
  organized air shows, organized fly-in activities, organized
  exhibitions, youth education events, organized aerobatic competition,
  fly-ins or meets, and movie or television productions. The duration of
  an airworthiness certificate for exhibition may be unlimited.

Here is an example of how to do it I found on a old page from the Robinson V8 Seabee Company website. (I found the page in the internet cache, so it is likely this method isn't foolproof)

STEP 1

Submit bill of sale for project Aircraft as "bought for salvage Parts" to the FAA. Add a separate letter of salvage in order to remove it from the FAA registry as Salvaged. This de-registers this A/C and is an important first step.

STEP 2

Obtain written permission from your local FAA Flight Standards District Office (FSDO) inspector in order to remove the data tag from the salvaged project aircraft. This step represents a great opportunity to develop a positive relationship with the FSDO inspector with whom you'll be working to complete the process. Be straightforward and explain that you require his help in order to certify your project in accordance with 14 CFR § 21.193, under a Special Airworthiness Certificate for the purposes of operating an aircraft in the experimental exhibition group 2 - Piston Engine Aircraft category, for the purposes of:

  Demonstrating flight proficiency; Demonstrating the superior engine
  reliability of modern V8 engines; and  Participating in exhibition of
  the aircraft at airshows and public event in order to educate the
  public about the unique and interesting characteristics of this
  aircraft

It is important to understand that the FAA FSDO inspectors are busy folks, and that they will appreciate the fact that you've done your homework. Maintain professionalism and don't expect an answer on the spot, as these inspectors have a number of strict procedures and guidelines within which they must work to accomplish the goal of certifying your aircraft. They deal with a great variety of aircraft and requests and may require some time to get up to speed on your specific request and understand the nature of your Robinson V8 aircraft.

STEP 3

Reserve a new N number on the FAA web site.

When your new N-number is confirmed  by the FAA, simply submit forms 8050-88 and 8050-1 for the new N number as:

  Manufacturer (preferably your new LLC Company or yourself). It cannot
  be the old manufacturer of the salvaged parts. Model  (Example:
  Military Seabee OA-15) or whatever you want to call it.  It cannot be
  the old model of the salvaged parts.

These forms need to be sent to the FAA Oklahoma City Registration Branch.

When your project is completed and ready for airworthiness inspection and operating limitations, issue a program letter to your FSDO inspector.  With FAA application for airworthiness form 8130.6.  They will take it from there.

Here is an example of program letter:

  Program Letter Nxxxx

  Date:  May xx, 20xx

  To:  Mr. FAA Inspector

  Federal Aviation Administration

  XXXXX Flight Standards District Office

  1234 Maple Lane

  anytown, state zipcode

  In accordance with 14 CFR § 21.193,  I request a Special Airworthiness
  Certificate for my aircraft Nxxxx for the purpose of operating an
  experimental exhibition, group 2 -  Piston Engine Aircraft. 1) For
  purposes of demonstrating flight proficency.  2) To demonstrate the
  superior engine reliability of modern V8 Engines.  3) To participate
  in exhibition of the aircraft at airshows and public events to educate
  the public about the unique and interesting characteristics of this
  aircraft.

  The aircraft description is as follows:

  Manufacturer: Your LLC                                    Registration
  No.:    Nxxxx

  Model:  Your model
  Serial No.:    xxxxx       Engine Make/Model: Robinson  LSV
  No. of Engines:    01 Propeller Make/Model:    xxxxx

  Number of Seats: Four

  The aircraft will be available for inspection at it’s base airport:
  (your airport and hangar location).

  The aircraft will be weighed prior to flight to determine weight and
  balance data. The marking requirements of Part 45 will be complied
  with prior to flight, including permanent attachment of a fireproof
  identification (data) plate, permanent application of appropriate
  registration marks.

  The following placards will be displayed in the cockpit in full view
  of all occupants:

  The word “EXPERIMENTAL" displayed near the entrance to the cabin or
  cockpit; minimum 2 inches, maximum 6 inches in height.

  "Passenger Warning – This Aircraft Does Not Comply With Federal Safety
  Regulations For Standard Aircraft" .

  Instruments and system controls will be adequately marked, identified,
  and function properly prior to flight.

  The power plant /propeller will be ground-run to sufficiently
  determine they are operating properly for flight.

  The Aircraft will be maintained under an Annual condition inspection
  that meets the scope and detail of 14CFR part 43, Appendix D.

  I request that airworthiness certification operating limitations be
  issued permitting me to operate the aircraft in phase one within 50
  Nautical mile radius of (Your Base Airport) with the exception of all
  A,B,C and restricted airspace and avoiding flight over populated
  areas.  Ten hours of  phase one flight tests will  be conducted to
  demonstrate control ability, engine reliability and establish the
  flight envelope.   After Phase 1 flight test completion,  I plan to
  operate the aircraft under Phase two operating limitations under
  VFR/day and VFR/night conditions under a group 2 Experimental
  Exhibition airworthiness certification within the continental U.S.
  proficiency area.

  Kind Regards,

  You


How could so many drones establish contact with ATC?

I'm not sure about everywhere but in the U.S. there is an app called "Airmap" Link to webpage. It's built for commercial drone operators but it can also be used by people flying for fun.

There is a flight plan portion of the app that allows you to file for a flight. You specify time of takeoff, radius you'll fly in, altitude and aircraft. This is then submitted for approval from the FAA.

It takes a matter of seconds and your approved, or not depending on the situation. It also has a map portion that displays the other approved flight plans in the area, if the pilot made his public, so you could even use this to join other's flying at the park if you see a flight pop up or something like that.

This could be a viable answer for India as well, coupled with a mini ADS-B, like CrossRoads mentioned, could prove even better.


How much damage could a landing gear malfunction do?

According to Belly landing:

  During a belly landing, there is normally extensive damage to the airplane. Belly landings carry the risk that the aircraft may flip over, disintegrate, or catch fire if it lands too fast or too hard. Extreme precision is needed to ensure that the plane lands as straight and level as possible while maintaining enough airspeed to maintain control. Strong crosswinds, low visibility, damage to the airplane, or unresponsive instruments or controls greatly increase the danger of performing a belly landing. Still, belly landings are one of the most common types of aircraft accidents, and are normally not fatal if executed carefully.

It is possible that the friction from a belly landing could wear a hole through the underside of the fuselage. However, even if this were to happen, airliners carry the passengers and crew in the upper half of the fuselage, so nobody would be likely to notice (from inside the aircraft before emergency evacuation).


It looks a lot like a variant or a copy of the Curtiss Model E (aka Curtiss A1) from 1912:

There is a youtube video of it flying in 2011.


Is there a standard for the trip paperwork packages that are used by the airlines?

For national flights, FAA prefers ICAO flight plan. For international flights, ICAO format must be used, From FAA Flight Planning Information:

  The FAA prefers users to file ICAO format flight plans for all flights. An ICAO format flight plan MUST be used when:

  The flight will enter international airspace, including oceanic airspace controlled by FAA facilities.
  The flight expects routing or separation based on Performance Based Navigation (PBN), e.g. RNAV 1.
  The flight will enter RVSM airspace.
  The flight expects services based on ADS-B.

EASA follows a format similar to ICAO.

The flight plan usually consists of the following:

Aircraft type and identification.
Flight Rules.
Equipment.
Source, destination, departure time and (estimated) arrival time.
Route details.

among other things.

The following image shows the ICAO international flight plan

Image from Form 7233-4 - Pre-Flight Pilot Checklist and International Flight Plan from faa.gov

The following shows the domestic flight plan from FAA. Note that the ICAO format may be followed in domestic flights too.

Image from Form 7233-1 - Flight Plan from faa.gov


I assume your question is about Declination/Variation, not Deviation that is addressed with the compass correction card.  It's confusing because you are reading the compass card from behind so to speak and you are rotating around the magnet, which is always aligned with Magnetic North, when you turn.
So forget about the magnet alignment and just consider the compass card indication that is telling your where the nose of the airplane is pointing, and think it through this way:
If you are flying straight toward the Magnetic Pole on the 10 Deg E Variation line, your compass heading will be 360/0 Magnetic, and your True Heading will be 10 Deg, because the nose is pointed 10 Deg to the right of the True North Pole with your compass showing 360/0 Magnetic.
If you are flying straight toward the True North Pole, your true heading is 360/0 True, and your Magnetic heading will reflect the fact that you are pointing 10 degrees to the left of the Magnetic Pole in order to point straight at the North Pole.  This will show as 350 on your compass.
Hence the "East is Least" rule for Easterly Deviation (West of the Agonic Line). To fly a specific True Heading, point so that the Compass indicates 10 Deg LESS (least=less=subtract from True for a Magnetic heading to fly) than your target True Heading; to fly 360 True, Point at 350 Magnetic.
So, per your question, if you are flying 360/0 True, that is, pointing straight at the North Pole, your compass will show 350 Magnetic if you are on the line of 10 Deg Easterly Declination/Variation.


What are the curved centerlines at taxiway intersections for?

The line along taxiway centreline is meant to provide guidance before initiating the turn. You're right that in a large aircraft they would lose sight of the centreline when they're over it, but it gives the pilot an idea of where they need to keep the nose in order to keep the outer main wheels behind them on the taxiway surface.
For example, in Canada, Transport Canada document TP312 (Aerodrome Standards and Recommended Practices) define how you need to place the centreline in order for the outer main wheels to remain at least a certain distance from the taxiway edge. (I believe the United States would have very similar rules; I just don't know the names of the appropriate documents)

Taxiway Curves
3.4.1.6 Recommendation - Changes in direction of taxiways should be as few and small as possible. The radii of the curves should be compatible with the manoeuvring capability and normal taxiing speeds of the aeroplanes for which the taxiway is intended. The design of the curve should be such that, when the cockpit of the aeroplane remains over the taxiway centre line markings, the clearance distance between the outer main wheels of the aeroplane and the edge of the taxiway should not be less than those specified in 3.4.1.3.

Think about when a large aircraft has to make a big turn (>90degrees). If there was no indication on the surface about how to take the turn in a large aircraft, you could inadvertently take it too early and run the main wheels off the pavement.
Here's an example of an aircraft following the centreline with its nose as best as possible in order to keep the main wheels in the right spot.


According to Wikipedia, no. The last one was retired in 2010.


Is it allowed to listen to music while piloting a plane?

Many aviation headsets either have an Aux-jack or a bluetooth connection, and listening to music is specifically mentioned as a feature.

(Link to headset)
(Link to adapter)

Some headsets even have a feature that detects radio-communications, and immediately silences the music.

The FAA has no problem with pilots listening to music provided its not distracting.   Individual company policies may differ.


Why do my flights always use runway 24L at LAX airport?

Two words: sample size. Eventually, you will use another one :)

There are only 4 runways, and they are all used heavily.

LAX normally has a westerly traffic flow, with aircraft landing/taking off toward the ocean.

How the airport operates:

  At all times, the inboard runways shall be preferred to the outboard
  runways for departures

and

  well over 90% of all operations use the preferred runways

Quotes from this document. Nice graphics can be found in there, too.