Is it possible for aircraft to transfer from low to high airways?

The use of airways is, as you already specified, based on altitude/flight level. To be able to transition from higher airways to lower airways and vice versa, they need to intersect at NAVAIDs, such as fixes, VORs or NDBs. Where no restrictions are in place for the use of an airway, the flightplan can just contain the fix where the transition from lower to upper airway will take place. Let's take a look at this flightplan route from EGLL - London Heathrow to EDDG - Münster-Osnabrück:

DET UL6 DVR UL9 KONAN UL607 SPI UY862 PODEN Y862 KENUM UZ907 ABAMI Z907 HMM

Lower and upper airways in Europe are distinguished by prefixing the airway designator with a U for Upper. At the end of our flight to Münster, we intend to switch from UZ907 to Z907, because UZ907 does not connect KENUM to HMM. The flightplan routing validator at the CFMU understands that HMM is a STAR/transition entry point to Münster and therefore considers the airways altitude restrictions to be met during descent.

If this was not the case and we would like to use airways restricted to certain altitudes/flightlevels, we would need to indicate this in the flightplan. Example:

Airways Z1 can only be used between FL195 and 245, airways UZ2 can only be used above FL245. We want to file our flightplan with a step climb and a final cruise level of FL290:

With RFL290 entered into the validator, the flightplan would not be accepted, as Z1 is only available below FL245. The portion of the flightplan to be accepted would need to be:

[...] ABCDE/F230N0260 Z1 FGHIJ/F290N0270 UZ2 KLMNO [...]

In summary, you can switch between upper and lower airways, if you can meet the altitude/flightlevel restrictions and any other restriction bound to the airway.

  ICAO flavored anwer added on request by question op, even though original question is tagged with FAA.


What are the restrictions preventing more intelligent autopilot systems?

Under the FAA there are not really regulations that limit the ability of an autopilot and shy of takeoff most modern systems are capable of performing most of a full flight with no pilot input (aside from route updates etc). Ultimately any aircraft system will have to get certified and this involves rigorous testing as well as demonstrations the system works under all stated cases.

There is however a bit of a logic issue in your statement:

  For example, during flight under certain condition where some sensors
  are failed and flight control system reverts back to direct law (in
  case of FBW) and the intelligent system autopilot recognizes this case
  so it helps pilot to decide what to do or controls the aircraft
  thoroughly

The reason the autopilot disengages or disconnects is because, due to the sensor failure, it no longer has the information it needs to properly control the aircraft. No matter how smart the system is, without proper sensor input, positive control is not possible or would be logically unsound. This is even true for human pilots and was in part the issue that lead to the Air France 447 disaster.

There is a broader question here of autopilots potentially handling emergencies which is a bit different than a sensor failure (read pitot static failure). This is already in place in part on some aircraft and as time moves we see more and more of it. Aircraft are now capable of detecting a depressurization and automatically descending to a safe altitude; even new small GA planes have this feature. Autopilots also now have forms of automatic level mode which will bring the aircraft back to a straight and level attitude at the push of a button.

This also comes down in part to design philosophy. This is highly opinionated so I'll stay away from it on this site, but there is hard data to support both cases: in the event of an emergency, is a pilot or computer system better equipped to handle the situation?


How dangerous was the turbulence on this commercial flight?

Very little to go on (non-pilots are lousy at classifying turbulence) but my best guess is that you experienced moderate turbulence.

If it was severe, your description would have been something more like this:

  I couldn't focus my eyes to see. Someone who wasn't belted down was
  flung violently against the ceiling, then slammed to the floor. The
  captain was very assertive, telling the FAs to be seated immediately and
  that all passengers must strap in. The flight attendants wedged the
  service carts into the gaps between the seats and asked some
  passengers to hold them down, before sitting down and securing
  themselves in with their full 4 point harness. During the worst of it, there was no way anyone would have been able to stand, even if you were holding onto the seats or walls. Some overhead bins
  popped open strewing their
  contents about the cabin. There was coffee, cups, plastic glasses,
  books, etc. flying around EVERYWHERE. Several
  people had to be taken off the plane by stretcher.

Pilots are not "scared to land". If it's not safe, they will divert. If the approach is wrong, they will "go around" (both perfectly normal) and spacing issues are the most likely reason. Why would the captain lie?

Ask a pilot.

The reaction of passengers is not a good indicator of the level of turbulence but the bottom line is, aircraft are designed to cope with the worst turbulence, and then some. You were perfectly safe.

I have to take issue with your use of "air hostesses", I believe you mean "cabin crew" or "flight attendants".  We stopped calling them that when we realised that they are actually professionals with a vital safety role as their primary function and are of both genders.


Far as I can tell, there are no passive or active air quality monitoring devices on the A320. The cabin air systems on modern airliners are designed against an air quality standard, and their performance is tested with equipment that is installed on the test aircraft for that specific purpose.

EASA published the results of an air quality campaign test program in 2017.

  In total, 69 measurement flights were performed between July 2015 and
  June 2016 on 8 types of aeroplane/engine configurations. This included
  61 flights on aeroplanes equipped with engine bleed air systems, and 8
  flights on Boeing 787 which is equipped with electrical compressors
  (‘bleed free’ system). For all flights, measurement equipment was
  installed in the cockpit and in the cabin.

  The results show that the cabin/cockpit air quality is similar or
  better than what is observed in normal indoor environments (offices,
  schools, kinder gardens or dwellings). No occupational exposure limits
  and guidelines were exceeded. Special attention was paid to
  organophosphates, in particular TCP (Tri Cresyl Phosphates) with the
  use of high sensitivity analysis techniques. Only traces of TCP meta-
  and para-isomers were sometime detected in all aeroplane types, but no
  ortho-isomers were detected.


Is it possible to split a NOTAM in two messages in case it is too long to fit in a single message?

Multi-part NOTAMs seem to be part of ICAO standard, as far as googling reveals. I can’t seem to find a definitive reference though.

An example - and from experience a relatively reliable one - for a multi-part NOTAM is the infamous Sydney crane list, at time of writing in NOTAM H6002/18, which at the moment comes in three parts and has the part listing in field A):

  H6002/18 NOTAMR H5974/18
  Q) YMMM/QOBCE/IV/M/AE/000/999/3357S15111E008
  A) YSSY PART 1 OF 3
  B) 1811190334
  C) 1811300500 EST
  E) OBSTACLE CRANES AT FLW LOCATIONS
  239FT AMSL BRG 002 MAG 1.58NM FM ARP
  497FT AMSL BRG 002 MAG 3.82NM FM ARP
  220FT AMSL BRG 002 MAG 1.38NM FM ARP OBST UNLIT
  413FT AMSL BRG 003 MAG 3.09NM FM ARP
  410FT AMSL BRG 003 MAG 3.14NM FM ARP
  577FT AMSL BRG 003 MAG 4.65NM FM ARP
  685FT AMSL BRG 004 MAG 4.26NM FM ARP
  249FT AMSL BRG 004 MAG 2.98NM FM ARP
  413FT AMSL BRG 004 MAG 3.18NM FM ARP
  224FT AMSL BRG 005 MAG 1.53NM FM ARP OBST UNLIT
  500FT AMSL BRG 005 MAG 3.42NM FM ARP
  953FT AMSL BRG 005 MAG 5.26NM FM ARP
  623FT AMSL BRG 006 MAG 4.54NM FM ARP
  PART 1 OF 3

Found at FAA pilot briefing site.


Where do flight sims get their data on aircraft flight characteristics?

It comes from a few places and it depends on the type of simulator you are talking about, while the data is not necessarily "confidential" I would call it proprietary although much of it is actually out there:
The Public Domain: Home simulators like X-Plane offer the ability to build your own aircraft models and there are many readily available for sale. People may build these planes experimentally or based on the associated POH information. In many cases the airfoil information for light singles like the Cessna 172 is fairly readily available since its based on a specific NACA airfoil.
The aircraft companies: Since a great deal of training occurs in D-Level simulators these days (because its cheaper than burning Jet-A) the aircraft manufacturers may also build simulators for the real aircraft they build in this case they have the engineering data on hand to build the models.

A great deal of the "experience" also has to do with things that have nothing to do with the aircraft flight model. Things like weather simulation, graphics, airport markings, radio chatter, cockpit sounds, button availability, instrument response and avionics functionality. When I fly my sim its just as important to me that I can simulate the same GPS unit (Garmin 430) that I fly with as is the ability for the 172 to fly like it does in real IFR conditions.


What altitude to fly on a STAR when it reads "expect"?

Terrible question (not your question, but the test question).

As far as I can tell, there are NO altitudes on the arrival that are mandatory; everything is an "expect" altitude only.

When you are "cleared for the STELA ONE arrival", you are cleared to (required to) fly the lateral ground track, and comply with any airspeeds stated on the chart ("cross at xxx knots", not "expect to cross at xxx knots" restrictions).  That clearance by itself doesn't clear you for any altitudes, even ones that are mandatory on the chart.

When you are cleared to "Descend Via the STELA ONE" arrival, then you are additionally cleared for all mandatory altitudes.  (Which I don't see any of on this chart, but I may have missed one -- NOS formatting isn't the best.)  Importantly, if the arrival has published altitudes to cross A at or above FL 230, cross B at or below FL 200, cross C at 12,000', and expect to cross D at 5000' (and no other altitudes after D), then you are ONLY cleared down to 12,000' -- you are NOT, in that case, cleared for the 5000' altitude.  You can expect it (i.e. load it in the FMC), but you can't depart 12,000' without explicit ATC clearance (i.e. don't spin  the 5000' into the altitude window on the mode control panel until ATC says "cross D at 5000").

Yeah, it's a "gotcha".  Really poor human factors design for an arrival to do that, IMHO, but there are a few of those out there.

Now, flying the STELA ONE, you're PROBABLY going to end up crossing STELA at 11,000', but until they assign you that altitude, you aren't cleared to do so.  "Expect" altitudes on an arrival have to be explicitly given by ATC -- "Descend Via" doesn't include those.

I don't know what other answers you had on the knowledge test besides 11,000', but my first guess would be that something along the lines of "not enough information given to know" or "cannot be determined" or "last assigned" would be better than "11,000" if the question asked something along the lines of, "having been assigned this arrival, at what altitude are you cleared to cross the STELA waypoint?"  With only clearance for the arrival itself, you haven't been cleared for ANY altitude change.

I don't much like that arrival since it has no mandatory altitudes at all, and I really don't like that question.  Have to love the FAA, sometimes!


What do these weather depiction chart symbols mean?

Since the other user posted a link that contained the answer that could in the future go 404, I'll provide the answer I found there.

The first symbol means "Fog in patches"

The second symbol is not present but by extrapolations likely means either "Mist in patches" or "Mist with sky visible".  The former seems more likely to me.

The third symbol means "Fog, sky visible."


Why does elevator dropdown occur in some loss-of-flight-controls accidents, but not others?

The mechanical or hydromechanical control system transmits the forces both ways, potentially amplified in the later case. When the pilot trims the plane so he is not applying any force on the control column, all the forces on the elevator are balanced and this includes gravity.

So when the control links are broken, the elevator will return to its trimmed position. In that condition, the plane will maintain speed with pitch, oscillating around the equilibrium in a Phugoid oscillation.

In the later four cases, the planes were likely trimmed, and had engine power left, so they remained controllable for some time.

In the LOT 007 case the aircraft was almost certainly not trimmed – the pilot could just hold the control column and not bother with the trim – and it lost most power, so it pitched down immediately.

The THY 981 either for some reason was not trimmed, or maybe the stabilizer moved a bit as the control links severed. I don't think there is enough information to tell for sure.

Also in the LOT 5055 case it is not clear the plane did not initially pitch down as the trim was still operating (until the spreading fire burned the power supply to it) and they had enough altitude to regain control by using it.


What are cloud clearance requirements around scuds?

From a preponderance of caution, my gauge on clouds is that if you can not see through them to fly by reference to the ground or the natural horizon, it is a cloud. And, a cloud, by any other name (scud, wisp, fog, etc.), is still a cloud. It will obscure visibility.
The question that you have to ask yourself is, “What is the purpose of VFR cloud clearance?” Were you able to see and avoid an aircraft if conflicting traffic was present? Would another aircraft be able to see and avoid you?


Why is the AWACS' rotodome located at the back and over the aircraft?

It's mounted dorsally in large part because it's simply too large to fit beneath the fuselage.

The rotodome has to be that large because inside is actually a planar array. The radar itself isn't round, nor aerodynamic, so it's wrapped in a smooth fairing that presents the same profile regardless of which direction the array is facing.

Caption: The Northrop Grumman AN/APY-1/2 AWACS multi-mode radar inside the E-3D rotodome. (Credit: Scott Carson. Twitter.)

Some airborne radars do not rotate and can indeed be mounted below the fuselage, like the E-8 JSTARS' APY-7 (primarily a ground surveillance radar):

(Credit: USAF. Link.)

Pave Mover, an APY-7 prototype:

(Credit: Daderot. Link.)

The cancelled E-10 (planned E-3 Sentry and E-8 JSTARS successor) also had a similar under-nose longitudinal array.

(Credit: Defense Industry Daily. Link.)

However, most larger, non-rotating arrays are mounted dorsally and longitudinally, like the Boeing 737 AEW&C:

(Credit: Seattle Aviator. Link.)

  [Question:] Moreover, it seems logical to put the rotodome under the aircraft. Its
  mission is to observe airspace under the aircraft to detect hostiles
  flying low enough to avoid detection by ground radar.

Not exclusively. Low-altitude penetrators aren't the only targets. AWACS is also tasked with finding medium to high altitude aircraft, both watching for enemies (eg firing "AWCAS killers") and keeping track of friendlies.

  [Question:] By mounting the
  rotodome above the fuselage, the aircraft's wings may disturb the
  radar mounted above them.

You don't need a lot of depression to observe things at medium to long range. At 30,000 ft, the horizon sits just a few degree below level, and even at 30 miles (which is very close) a low-altitude target is just -10 degrees. There's also a fair bit of clearance between the elevated dome and the fuselage/wings, which reduces how much of the ground is masked (roughly -20 degrees from radar to wingtip). Together, there's probably fairly little that an E-3 wouldn't be able to see. You'd have to be practically underneath it at close range. And then you'd have to deal with the fighter escorts...


For how long are state and federal aircraft registrations valid?

Federal registration is for three years, according to the FAA (the actual regulations are in 14 CFR 47.40):

  Aircraft registration issued due to renewal expires three years from the expiration date of the previous certificate.
  Aircraft registration issued to a new, import, or reinstated aircraft entering or re-entering the U.S. Civil Aircraft Register
  expires three years after the last day of the month in which it is
  issued.

State registration - if any - is up to each state so you need to check with the state where the aircraft's owner registered it.


With a well functioning angle of attack sensor the 737 MAX was safe. Only a malfunction which let the sensor report a higher angle than real would result in the repeated attempt of the MCAS to trim the airplane nose down.
Such a malfunction is a rare event (10 per year across all types flying in the US). This should explain the many uneventful 737 flights. However, to rely on only one sensor was criminally negligent. A safe design would have redundancy built in. Ironically, the 737 MAX has such a second sensor (just opposite of the one which fed the MCAS) but the software did not crosscheck the readings.

Additional remarks
Now there have been so many comments, and they all have been caused by my rather cursory description of the problem, that I better expand this answer so people will not feel a need to add more comments.
MCAS was already introduced with the Boeing 707 and the KC-46 (tanker version of the 767), but would only add nose-down trim once if a prescribed angle of attack is exceeded.
With the more powerful LEAP engines of the 737 MAX, pitch stability at high angle of attack and high thrust would become negative, something that would make any airplane immediately impossible to certify under current regulations for civil aircraft. The more forward position of the intakes and the high suction on the intake at high angle of attack would had required a larger horizontal tail if proper design rules would had been applied.
But Boeing is run by ex-McDonnell-Douglas management where cost-cutting is more important than applying proper design rules. A larger horizontal tail would result in structural changes throughout the rear part of the airplane, require new jigs and tests and a much more complex certification. Simpler solutions did not work out, either: Several aerodynamic solutions were introduced such as revising the leading edge stall strip and modifying the leading edge vortilons but they were insufficient to pass regulation. So the instability had to be fixed in software.
The result was a system that read inputs from a single sensor, and under the right conditions (flaps up and autopilot disengaged) changed pitch nose-down by 2.5 degrees stabilizer rotation when a specified angle of attack was exceeded and repeated this mindlessly after five seconds if the angle of attack was still too high. No provisions had been made for a defective sensor. Concerns by engineers and test pilots about the hazards resulting from a sensor failure were ultimately dismissed. Eventually, Boeing officially assumed that pilots would respond to an unexpected MCAS activation as if it were a runaway stabilizer trim event, and do so within four seconds.
All 737s have two AoA sensors, but the MAX MCAS relied on only one sensor at a time, switching between the left and right one each flight. By the way, the KC-46 MCAS, although less powerful, uses the inputs of two sensors and trims the stabilizer by just 0.6°, and only once per activation.
Next, in order to limit the amount of pilot training for the new type to Level B (no simulator), the MAX should feel to the pilot like a next generation 737. This made it possible to fly the MAX with the type rating for a regular 737, a big selling argument to airlines which already operated the 737. MCAS helped to achieve this, and information about its details was not part of mandatory training (which consisted of a two hour iPad tutorial). By repeating the pitch trim change, the MCAS had become safety critical where earlier versions were not. Nevertheless, information about it was hidden and most pilots did not even know of its existence after their transition to the MAX.
Another factor was the insufficient funding and regulatory capture of the FAA in the last decades which had less personnel to check new designs, so it gladly handed much of the testing for certification to the manufacturers: Boeing Authorized Representatives are Boeing employees who are granted special permission to represent the interests of the FAA and to act on the FAA’s behalf in validating aircraft systems and designs’ compliance with FAA requirements. The core function of the certification process, to let a second pair of trained eyes look over the new stuff, was outsourced to the same people who had authorized those designs. Also, the capacity of MCAS was misrepresented to the FAA as an addition to speed trim in order to avoid more scrutiny and testing. Later investigations found a disturbing trend of FAA management treating operators favorably and overruling the work of technical experts.
As usual, several opportunities to avoid what happened were missed and several causes conspired to make MCAS the trap it became.


How can a small ducted fan produce a large amount of thrust?

Thrust depends greatly on diameter, so your curiosity is reasonable.
Why:  A first-principles answer says that (static) thrust depends directly on the rate of mass flow through the duct.  Because the duct's area is small, the speed of air through the duct must be large, and thus what must also be large is the fan's (static) pitch speed and its RPM.
See https://www.grc.nasa.gov/www/k-12/airplane/thrsteq.html for the case $p_e = p_0$.
For 175 N thrust, Schuebeler says the fan turns at 20,000 rpm and needs 12 kW.  Those numbers are not vastly different from an unshrouded 15 cm propeller, or a small turbine (a JetCat P220 does 220 N at 725 mL/min, converted via kerosene's MJ/L to roughly 450 kW; there's much more waste heat in a turbine's exhaust than in a ducted fan's gradually warming battery pack).
How:  Tight manufacturing tolerances, so the blades don't vibrate from imbalance, so the blades don't deform or break at high rpm, and so not too much air leaks around the gap between the blade tips and the walls of the duct.  (The same applies to turbines.)


What is this aircraft and the Air Force it belongs to?

Panavia Tornado, Royal Air Force (UK), 13 Squadron.

The aircraft in the question is identified as belonging to No. 13 Squadron by the distinctive green, yellow and black 'Squadron flash' painted on the aircraft side  below the front part of the cockpit.

Royal Air Force roundel

13 Squadron flash

Above: a Tornado of No. 13 Squadron as seen at the 2007 CIAF air show in the Czech Republic. The squadron flew Tornado GR.1A aircraft from 1990, and later the GR.4 and GR.4A variants.

Here is ZA401 (a GR.4) at RAF Leuchars in 2005 with the 13 Sqn flash painted on the tail as well as the normal place, as part of the Squadron's 90th anniversary celebrations:

No. 13 Squadron RAF (Wikipedia)


Why does the airport plate list a VASI that does not exist?

How does an oversight like this exist for such an extended period of time?

Because it doesn't get reported.

  Is this something that should be reported?

Yes, it should be reported, otherwise this oversight will exist for an extended period of time.

This dAFD website contains a link that should be followed to [r]eport any A/FD errors or changes. Somewhere down those links you'll find plethora of forms and rather confusing texts which seem not really helpful when you want to report a missing VASI. That brings us back to the answer on your first question.

Update:

In the comments, Kevin Cathcart pointed out the Aeronautical Data Inquiries form which is the appropriate form to flag the problem. Alternatively you can contact the NFDC (National Flight Data Center) via phone at 1-(866) 295-8236.

  Does this create a hazard to potential IFR traffic?

Whether it is a potential hazard depends mainly on the presence of other source of vertical guidance. Is there an ILS / gideslope active? No vertical guidance at all is a safety risk in low visibility conditions.


Is there currently any heat shielding and paint for speeds of up to Mach 6?

I'm reasonably certain the speed limit (so to speak) on the SR-71 wasn't to prevent its skin from melting.

The hottest the skin got during flight was less than 600 C. That's definitely hot--but it's a long ways short of the melting temperature of titanium (1668 C).

Early supersonic aircraft often had control problems, because the leading edge of the air foil would cause a shock wave that separated the air flow. The control surfaces at the trailing edge little enough air flowing smoothly that they lost authority.

In the X-15, they combated this by building a vertical stabilizer that was basically a V-shape--thin at the front, but much wider at the rear:

This would induce a lot of drag at low speed, but for the x-15, low speed wasn't really a major concern.

The SR-71 took a different approach, using a pair of vertical stabilizers.

The leading edge of each stabilizer produces a V-shaped shock wave. At (approximately) the normal cruising speed, that V comes back from the leading edge of one stabilizer, and hits against somewhere close to the trailing edge of the other. Thus, we still have a solid air flow across the trailing edge (and rudder) of each, and maintain nice directional stability.

For that to work, however, the angle from the leading edge of one stabilizer to the trailing edge of the other has to (approximately) match the angle of the shock-wave formed at the leading edge. Outside of the designed speed range, that no longer happens.

On the SR-71, the vertical stabilizers are angled somewhat. This gives a (still fairly narrow) range of speeds at which the aerodynamics "work", rather than having only one specific speed. Nonetheless, the difference in separation between the top and bottom of the stabilizers isn't very large, so the range of speeds at which it works is fairly narrow. If you try to exceed that range, your stabilizers no longer work, and your control over the aircraft quickly deteriorates.

Having said all that, however, the answer is a clear "yes", if heat were to become a problem, there are materials available that can withstand substantially higher heat than titanium. One obvious example would be the Inconel X that was used as the skin for the X-15 (which flew at a bit over mach 7). Another possibility would be carbon or ceramic tiles, like those used in the Space Shuttles (or some of the other heat shielding it used, such as flexible blankets).

Those have some fairly serious shortcomings so they'd probably be avoided unless absolutely necessary. Inconel X is quite a bit heavier than titanium, and while the ceramic tiles were quite heat resistant, they were fragile mechanically, which led to a lot of maintenance work on the shuttles.


How is combustion flame maintained in the combustion chamber after igniters are switched off?

How does a candles flame sustain itself after you have lit it?  It stays lit by continually burning fuel.  The jet engine works the same way.  Once the fire is lit (by the ignitors) it is constantly burning.  Air is constantly being supplied by the compressor and fuel is constantly being supplied by pumps.

This is fundamentally different to a traditional combustion engine you might be trying to reconcile this idea against.  In a 4-stroke internal combustion engine, for example, you have intake, compression, power and exhaust happening separately and you need spark plugs (or glow plugs) to ignite the fuel each cycle.  In a jet engine, however, instead of 4 independent cycles you have a constant flow of air through the engine.  Air comes in the front, is compressed by the N2 stage and fed continually into the hot section where the fire is constantly burning and then exhausts through the back of the engine.

Look at it like a propane barbecue grill or a gas stovetop -- you only need the ignitor to start the fire. Once the fire is burning it stays that way until you turn off the flow of gas.


Can anyone identify what appears to be a crashed WWII German plane?

It's a P-47 Thunderbolt, the original "razorback" version (not the later ones with the bubble canopy and cut-down rear fuselage).  The instant giveaway is the V shaped windshield, which had the armour glass as a separate panel behind it (removed in the pic). The bubble canopy versions have the armour glass as the windshield itself, like most other fighters.
The German rudder/fin looks to be a piece of a the right tail boom of a Focke-Wulf FW 189.
My guess is that Bud is probably at a forward P-47 base that was an ex-Luftwaffe base (the brick wall behind suggests a large base with permanent buildings, possibly within Germany or Eastern France, in early 1945) and therefore still strewn with German wrecks.  The Jug in the picture has had what looks to have been a gear up landing and was dragged away to a bone yard area, and is being cannibalized for parts as required.


Non-fueled, bladeless, minimally-noisy aviation engine --- Science fiction or real theoretical science?

Electric propulsion using ion thrusters is already in use for space applications. Today's ion thrusters deliver very high specific impulse at low power (typically in the order of 10 to 1000 W). Lower or higher outputs are possible and subject of current research and development.
Ion thrusters work great in the vacuum/free fall environment where low thrust over long durations is useful, and electric energy can be generated on the spot with solar panels.

The usage of ion thrusters in the atmosphere is possible, but there are major challenges:

planes require a lot of thrust during take-off
the propellant does not contain the energy to drive the thruster
the atmospheric pressure changes all the working paramters. Existing ion thrusters for space are not useful in the atmosphere.

Today, ion thrusters are not ready for aviation and it might never happen, but there is some research going in this direction. Personally I do not believe that ion thrusters are useful for low altitude, but I can well imagine a scramjet engine for high altitude using ion thrust technology. In any case, even an ion thruster without any moving parts cannot be silent when working in the atmosphere. The particles expelled at very high speed will create a lot of noise, similar to a welding torch.


How does the ski shape of an aircraft carrier deck help for take off?

The Ski jump was originally used by the UK Royal Navy to assist Harriers in getting airborne.

The Harrier cannot take-off vertically when fully loaded.  In all models, the thrust is lower than the maximum weight.  Therefore, they need to do a "short take-off" where the thrust nozzles are angled rearwards to provide thrust, then partially angled downwards as speed is gained to produce enough lift from the wings, and thrust angled downwards, to climb away.  Watch the nozzles closely at about 17 and 36 seconds in this video.  Try not to watch the poor chaps forehead too closely at 20 seconds.  Also watch this video.  At about 16 seconds, you can see the pilots left hand pull back on the nozzle angle lever as he passes the end of the deck.

Now imagine a flat deck on an aircraft carrier.  Operations must be able to carry on in rough seas.  You accelerate down the deck and fly off the end, just as the deck dips downwards as the carrier rides a large wave.  You are pointed straight at the sea.  In order to avoid flying into the sea, you need to climb, which means pulling G and a lot of power at low speed which the Harrier just didn't have.

Now consider the ski jump.  There are two effects.

The jump is angled so that even in the worst seas in which operations will continue, the bow pitching down will not point an aircaft leaving the end of the jump towards the sea.  The aircraft will always be pitched upwards.
Imagine driving a fast car up the jump and off the end.  It will be thrown up and forward in a parabola.  Even a car, which cannot fly, will be pointing up for a few seconds, then level for few seconds before falling into the sea.  But instead of a car, you are driving a jet which can fly and has thrust.

The aircraft will angle the nozzles rearwards for maximum acceleration until it leaves the jump. The wings are now generating significant lift, let's say 50% of that required to climb away.  As you leave the end of the jump, you angle the nozzles downwards so that you have the momentum of the aircraft and some rearward thrust maintaining lift on the wings whilst adding lift from the thrust vector having a downward component.

Those seconds of pointing up, then level, enable the aircraft to continue to accelerate until all of the lift required can be gained from the wing when the nozzles can now be angled rearward again to continue the acceleration. Take-off speed is therefore reduced and take-off distance is about halved meaning smaller, cheaper carriers.

That's how Harriers do it.  I imagine it's the same story for any other VSTOL aircraft.


What to do if the captain smells like alcohol?

Unfortunately, at least in the US, the regulations don't stipulate that you do anything. Airline policy is a different matter, and one which I cannot speak to, as it will be different in every case.

I can provide some background and my own take on this, but it's hard to have one exact answer (what if you're wrong?).

FAA regulations rely on pilots self-regulating. If a pilot drinks within an 8 hour (or, as is often policy for airlines, 12 hour) window prior to the flight, they are required to remove themselves from that flight. If they do not take this action, somebody else must. Often, this person is the First Officer, a junior pilot who has years of flying with pilots who might come to view them as untrustworthy. Perhaps this can help explain why it's such a difficult action to take.

This is a difficult topic, and one which regularly comes up during airline flight training. That said, the courses I took that discussed this scenario essentially landed on a couple of steps (this was years ago, this is probably a bit rusty):

Confront the pilot. Ask them if they've been drinking in the last X hours. If they claim they have not been, or they push back:
Attempt to explain to them the situation they're putting their career (and you) in;
Try to get them to remove themselves from the flight and contact a union representative.

Beyond that, I don't want to make suggestions. Getting them to talk to the union they are a member of is probably a wise idea, as they can offer possible solutions or arrange treatment if the pilot has alcohol abuse problems (which is not a huge stretch, if they're showing up to work reeking of booze). AOPA Flight Training has a blog post that discusses some similar scenarios.


Virtual breakers use solid-state relays:

A solid-state relay (SSR) is an electronic switching device that switches on or off when a small external voltage is applied across its control terminals.
The relay may be designed to switch either AC or DC to the load. It serves the same function as an electromechanical relay, but has no moving parts.

According to Boeing for its 787:

The remote power distribution units (RPDUs) are largely based on solid-state power controllers (SSPC) instead of the traditional thermal circuit breakers and relays.

The standards for the solid state power controllers in aircraft is set by BS ISO 8816.

Related: Where are the circuit breakers on the 787?


Do rotorcrafts like helicopters have autopilots?

Yes, helicopters can be fitted with autopilots. Some are very simple, others are quite advanced. The more advanced ones can, for instance, follow a pre-programmed route, climb/descent to a pre-selected altitude, fly an ILS approach, perform a go-around automatically.

They are not ordinarily found in small helicopters due to cost and lack of necessity. All modern offshore helicopters that I've encountered have them and they are used extensively. Usually they are engaged shortly after take-off and disengaged shortly before landing.


How strong is the A380 fuselage-wing joint?

how could it be trusted?

Like all aircraft, type certification requires that these be tested. I think the wings are tested to 1.5 x their load limit.
A380: STRUCTURAL STATIC TESTS

The A380’s structural static tests on began in November 2004, in preparation for the first flight clearance.
The tests included: Flight Test Installation (FTI) calibration test, maximum wing bending at limit load, ailerons and spoilers functioning test during max wing bend, fuselage pressure test, and fatigue tests and flight cycles simulation.

They place an airframe into a test rig and increase the load on the wings until the wings break. The empirical evidence is compared with the predictions made by mathematical models.

Airbus A380 wing test

Airbus A350 wing test ... (A350 torture video)

Boeing 787 wing test


Why is the nacelle outlet of the tail engine of the L-1011 Tristar lower than the engine itself?

As Federico points out, the engine is located directly in front of the exhaust portion. This is true for almost all engines with ducted arrangements. It's much easier to duct the cool, slow intake air to the engine than duct the hot, fast exhaust air away from it, for both temperature and drag reasons.

In this cutaway you can see the intake duct leading down to where the engine is:

Source

Putting the exhaust nozzle lower allows more room for rudder above it. Putting the nozzle higher, like on the DC-10 series, means the rudder is pushed higher up the tail.

This arrangement keeps the rudder as close to the vertical center of gravity as possible, which reduces the stress on the tail and limits the rolling motion induced by the rudder. It also keeps the engine forces close to the vertical center of gravity. This configuration also allows the supports to tie in to the existing structure at the rear of the fuselage. Placing the engine further up the tail would add surface area (and therefore drag), and require additional structure to support the engine above the fuselage.


Where can I get an list of ATC phraseology terms in Spanish?

ICAO has defined in their Annexes that English is only one of the available langauges to ICAO and that ATS should either use the language specified in the country's AIP or use English.

  1.2.9    Language proficiency

  1.2.9.1    Aeroplane, airship, helicopter and powered-lift pilots, air traffic controllers and aeronautical station operators
  shall demonstrate the ability to speak and understand the language used for radiotelephony communications to the level
  specified in the language proficiency requirements in Appendix 1.

  Note 2.— The provisions of 1.2.9 refer to Annex 10, Volume II, Chapter 5, whereby the language used for radiotelephony
  communications may be the language normally used by the station on the ground or English. In practice, therefore, there will
  be situations whereby flight crew members will only need to speak the language normally used by the station on the ground.

Personally, additional to my proficiency level in English, I also hold a Level 6 language proficiency German in my pilot's license.

Below is a screenshot of the Aerodrome Description for LEBL/Barcelona, taken from Spain's AIP. You see that ES/EN is listed as available languages.

If you are looking for Spanish Phraseology, you can find it with Argentina's Administracion Nacional de Aviacion Civil.


Are fly-by-wire fighters protected in AoA?

Brief answer: Yes, but the protection does not always work.

Most modern fighter aircraft have an AoA limiter. That is different from a stall warning – in case of the McDonnell Douglas F-4 the limit was only 23 degree, below the stall limit. The reason for the limit was the loss of directional stability above 23 degree AoA.

In case of the JAS-39 Gripen the limiter worked in a straight pitch-up but when the pilot repeatedly pitched up during a flight display over Stockholm, the dynamic response overpowered the AoA limiter and the aircraft stalled. It fell like a stone into a public park, miraculously without loss of life.

In another accident the JAS-39 FCS software got confused after the controls could not follow the change in angle of attack quickly enough when one aircraft flew through the wake of another, its adversary in an air combat exercise. This caused the safe limit of 20 degree to be exceeded and the aircraft became uncontrollable.


Why do airplanes lift up their nose to climb?

A climbing aircraft needs less aerodynamic lift than in horizontal flight, not more.

Now I have your attention, I hope. The reason is quite simple:

Lift equals weight, and just because the pilot choses a different flight path angle, the weight of the aircraft does not change. The total of all lifting forces must still balance the weight, but in climb you get a small lifting contribution from the engine(s) because its (their) thrust will point upwards just like the rest of the airframe.

Don't let the many arrows and greek letters confuse you. To be in equilibrium, lift (L, dark blue), drag (D, red), thrust (T, green) and weight (m⋅g, black) must add up such that they can be combined into a closed run of vectors. I've done this with the lighter-colored vectors around the weight. Since the flight path points upwards, so does the thrust which now has a small vertical component. The lift vector can be a little shorter now.

Consider the extreme case of vertical climb: Now all thrust supports the weight, and aerodynamic lift is no longer needed.

There is a second, much more subtle effect: When you climb, air gets thinner and engine performance goes down proportionally. At the same indicated air speed, the aircraft will continually decrease its climb speed, and this deceleration frees up a tiny inertial force, which again adds to lift and counteracts weight.

Conversely, at the beginning of a climb phase the aircraft needs to create momentarily more lift to accelerate itself upward. Only then, when climb speed increases, lift must be bigger than weight to overcome the inertial effect which at this moment works downwards. For the supernerds: If you integrate the lift deficit over time of the aforementioned effect and the extra lift over time for climb acceleration, both cancel exactly.

To answer your question directly: To climb you need to increase excess energy, not speed. This is normally done by increasing engine power output, or by trimming the airplane at a lower speed where drag is less, so more power remains for climbing. This question contains more details on how to get an aircraft to climb. Note especially @SteveV.'s bucket analogy.

If you use the airplane's kinetic energy as its source of thrust, the same mechanism can be applied to instationary climbs, where speed is traded for altitude, like in gliders.

The nose-up attitude is simply the result of a different flight path. Since the required aerodynamic lift will be almost the same, the angle of attack will also be almost the same and the whole aircraft needs to fly nose-up. This is similar to a car which has the same attitude towards the road, but when you drive uphill, both car and road will be tilted upwards.

This analogy breaks down when you change speed - flying at lower speed needs more angle of attack to still create the same lift, and this nose-up change will be added to your attitude angle.


Is this a Janet Airlines 737 at Area 51?

Probably yes.

Janet Airlines operates the Boeing 737-600 (and some Beechcraft turboprops), which has a wingspan of $ 34.32 \, \mathrm{m} $ and a total length of $ 31.24 \, \mathrm{m} $. I measured the size of the aircraft using the Google Maps distance tool:

The dimensions of $ \sim 34 \, \mathrm{m} $ span and $ \sim 30 \, \mathrm{m} $ length match (within the accuracy of the Google Maps image) the dimensions of the 737-600. The white fuselage paint also matches the Janet airlines aircraft:

(image source: Wikimedia)

Most civilian aircraft are painted white of course, but military aircraft are typically not. The red stripe is not visible from above, so it is impossible to say for sure, but since I don't expect many other white 737-600s to fly to Area 51, I think it is a fair bet to say this is indeed a Janet airlines aircraft.


What are the factors that limit how long an aircraft can stay aloft?

Maintenance is probably the biggest issue. What types of maintenance is needed and the failures that not performing those steps will lead to depends on the design of the aircraft.

For example, on a piston engine used in a small aircraft:

The engine will need oil replaced at some point, and unless a system was created to cycle in new oil in-flight this is probably the first thing that will break down after crew and fuel (as you mentioned). Oil breaking down will lead to early failure of the engine.

Fuel and air filters will get clogged, leading to the engine shutting down.

Which leads to engine wear. Eventually piston rings, ignition systems, etc. will wear out.


If the pilots used the brakes upon landing, would the force essentially slam the front wheel down?

If you get on the brakes hard after main touchdown, once the anti-skid is active following wheel spin-up (you can't land with brakes applied on any airliner with anti-skid - brakes are depressurized until after the main wheels start to spin and/or you are weight-on-wheels for a minimum time) and don't apply any additional compensating elevator, the nose will come down faster than if just hold the existing elevator input, and will contact a bit harder, but "slamming down" would be a bit extreme unless you also relieved some of the control back pressure as you did so. Then it would be a bit firm and if you were reckless enough you might blow the nose tires, and somebody would have a chat with you.

In practice though, on most jets you land the mains, then the nose in two separate actions and during that "second phase" you are applying elevator to modulate the sink rate of the nose to make it touch down reasonably gently for that "2nd landing".  If you were on the brakes hard at that point you would normally just compensate instinctively with extra elevator input to get a gentle landing of the nose.

You would certainly have enough tail power available to counteract the nose down torque of the braking at high speed.  But you would probably get scolded for getting on the brakes before nose wheel contact anyway, and a lot of pilots will keep their feet low on the pedals to avoid applying brake, then move them up once the nose wheel is down.


Are crossing restrictions on an ILS/LOC approach mandatory when flying on the glideslope?

Closest regulatory thing I could find :

ICAO Doc 8168 Section 4 Arrival and approach procedures

  1.7.5 Any constant descent angle shall clear all stepdown fix minimum crossing altitudes within any segment.

  5.2.5.1 A stepdown fix may be incorporated in some non-precision approach procedures

  5.5.5.2    The  protection  area  assumes  that  the  pilot  does  not  normally  deviate  from  the  centre  line  more  than  half-scale
  deflection  [...]   more  than  half  course  fly-up [...]  could
  place  the  aircraft  in  [...] airspace where loss of protection from
  obstacles can occur.

The writing leads me to believe that a precision approach should not contain stepdown fixes, and that the descent should be a continuous descent from FAP to MAP.

Then again, I could find nothing specific to prevent anyone from inserting an altitude restriction in a precision approach.

I cannot imagine what would be the point of coming down on a constant GS only to level off at 1000' then try to re-capture the GS just two miles from thouchdown. Talk about a stable approach...


So far no one has created an official database. By official I mean one that you can count on to be correct and up-to-date. There are a few people who have created databases, but they all come with the caveat that they don't guarantee the info is correct and current.

The thing is, I don't really know if you could create a reliable database with the laws the way they are. A few states have stepped in and written a preemption against local ordinances, so in those it would be fairly easy to do. But in other states there'd be no way to keep up with ordinances enacted by the the thousands of county and local governments, many of which don't maintain an easily-accessible method of publishing their laws, and most of which are written by people who know little about uas, so the laws are often very vague.

The laws are also changing quickly right now, creating an untenable situation for drone operators. The US Senate is currently considering a bill that specifically legislates against any possible fix to this situation. It's really a complete mess.

A few of the databases I have found are:

Jonathan Rupprecht Law Office database
National Conference of State Legislators
Drone Law Today State drone law reference book


How to determine individual wing loading of a triplane for stress analysis?

A stalled wing will still produce considerable lift, so it is not on - off. That said, the best you can do is to model the lift distribution at least in a vortex lattice code which correctly computes the mutual interference. This will give you very good results for attached flow and unstalled wings.

But triplanes have successfully been designed before the availability of computers, so for a first approximation distribute the load according to the wing incidence. Lift will be proportional to the angle of attack of each wing, calculated from the airfoil's zero-lift angle. Stagger will increase the local angle of attack of the forward wing and vice versa. How much depends on the ratio between stagger and vertical wing distance. The first solid theory of lift distribution was developed by Ludwig Prandtl and his pupil Max Munk, whose tabulations can be found in NACA Report 458 which is for biplanes but can be extended for triplanes.

If you like more recent literature: Even a publication from 2009 refers to Munk's tables, so they should still be relevant today. However, it finds a lift difference between positive and negative stagger that – according to Munk – should not exist.

Note that with struts and inter-wing bracing the whole triplane is your bending beam and will collectively carry the lift loads. Only with cantilevered wings will you need to worry about the root bending moment on individual wings. Bending between struts needs still to be carried by the single wing but will be small compared to the root bending of a cantilevered wing.


Are high-frequency flapping wings efficient and scalable at high Reynolds numbers?

Some English University researchers studied the tiny helicopter Black Hornet versus Colibri-wings as efficiency. It was shown that rotating wings have LESS LOSS as the flapping ones because the latter must surpass the inertia of the wings at each flap. The insect wings have little weight and so small inertia.  So high-frequency flapping is only for small devices. What is better in the animal wings is the aerodynamic itself> Search "leading-edge vortex" on Google. Why animals have no rotating wings? >there is no rotating device in animals, because they must be fully articulated, by design... Only maple-seeds have a sort of autogyro.


How to stabilize the aircraft flight after dropping boosters?

The most important aspect is the vertical distance between the booster's thrust vector and the center of gravity. Once the booster stops working or is dropped, a pitch trim change will be needed to compensate for the upset in the pitching moment balance.

Next, the horizontal distance between the boosters and the center of gravity will tell you how much the pitching moment is changed upon dropping the boosters.

If control authority is sufficient to trim all those pitching moment changes, stabilization should not be much of an issue, especially if a sufficiently sized tail gives sufficient pitch damping.


What's the difference between "HAND OFF" and "HAND OVER"?

In the U.S. Air Traffic Controllers initiate handoffs and receive handoffs.  Perhaps the term "hand over" is general term applied to the process of making/receiving a "handoff."

Here is the definition of "Handoff" from the Pilot/Controller's Glossary in the FAA JO Order 7110.65W, Air traffic Controller's handbook:

  HANDOFF
  −
    An  action  taken  to  transfer  the  radar
  identification  of  an  aircraft  from  one  controller  to
  another  if  the  aircraft  will  enter  the  receiving
  controller’s airspace
  and radio communications with
  the aircraft will be transferred.

I am unable to find the term "Hand Over" in the 7110.65W.


Although, I can not find an FAA reference for baro corrected altitude, my understanding is that baro corrected altitude is the Indicated Altitude on a pressure sensitive altimeter when the Kollsman Window is set to the correct current barometric pressure. This may be different than the Indicated Altitude on a non-adjustable/settable altimeter. It may also be different than the Indicated Altitude on a pressure sensitive altimeter set for a non-current altimeter setting.
In contrast, Pressure Altitude is the height above the standard datum plain set at an altitude where the barometric pressure is 29.92 inches of Mercury. You would get Indicated Altitude to match Pressure Altitude by setting the altimeter Kollsman Window to 29.92 inches of Mercury. 5is may not represent the height above Mean Sea Level.
True Altitude is the height above the 19 year average Mean Sea Level. It is consistent regardless of barometric pressure, temperature, humidity, geographic location, etc.
Pressure Altitude is the True Altitude adjusted for non-standard barometric pressure. Indicated Altitude may differ from True Altitude based on what barometric pressure (if ant) is used to calibrate the altimeter. Having to use an altimeter setting from a weather observation (ATIS) not located at the field of use or one that has not yet updated to current.


Is a full traffic pattern required when there is no traffic at an untowered airport?

See AC 90-66A - RECOMMENDED ‘STANDARD TRAFFIC  PATTERNS AND PRACTICES FOR AERONAUTICAL OPERATIONS AT AIRPORTS WITHOUT OPERATING CONTROL TOWERS  for information about uncontrolled airport traffic patterns.

It includes the following which says that while the FAA recommends using the full pattern, it is not required:

  7. GENERAL OPERATING PRACTICES.

  a. Use of standard traffic patterns for all ‘aircraft  and CTAF procedures by radio-equipped aircraft  are
  recommended at all airports without operating  control towers.
  However, it is recognized that other  traffic patterns may already be
  in common use  at some airports or that special circumstances or
  conditions exist that may prevent use of the standard  traffic pattern

And then:

  e. The FAA encourages pilots to use the standard  traffic pattern.
  However, for those pilots who choose  to execute a straight-in
  approach, maneuvering for  and execution of the approach should be
  completed  so as not to disrupt the flow of arriving and  departing
  traffic. Therefore, pilots operating in the  traffic pattern should be
  alert at all times to  aircraft executing straight-in approaches.

  f. Pilots who wish to conduct instrument  approaches should be
  particularly alert for other aircraft in the pattern SO as to avoid
  interrupting  the flow of traffic. Position reports on the CTAF
  should include distance and direction from the  airport, as well as
  the pilot’s intentions upon completion of the approach


Is the RAT pump on the A320 standard fitment or is it an "option"?

A RAT is never an optional piece of equipment. It is only there because the design of the aircraft systems require it in order for the aircraft to meet airworthiness certification.


What do these polygons mean on VFR charts?

To add a little to @abelenky's answer, you'll notice that each area has a identifier in it: SBR-522, SBP-505 etc. Those identifiers are made up of the ICAO country prefix, the airspace type, and a unique code. The airspace type can be Prohibited (P), Restricted (R) or Danger (D).

Since SB is the ICAO code for Brazil, SBR-522 is Brazil Restricted area #522; SBP-505 is Brazil Prohibited area#505 etc. I couldn't quickly see any nearby danger areas, but here's one in South Africa: FAD-193, near Port Elizabeth.

You can look up those codes in each country's Aeronautical Information Publication (AIP) or local equivalent to get more information about what each area is, what altitude it goes up to, any special rules etc.


How long will it take a new pilot to start flying more advanced planes like a Cirrus SR22T or Piper Malibu?

You have a few questions here that should be addressed individually.

  What is a realistic path for me?

Get your PPL then start to consider what you can fly/own. As you train you will inevitably learn about the various major airframes people fly and what it takes to own one.

As a word to the wise you should read this thread about a young guy who figured he could get his PPL and buy the fastest plane out there for his mission. Its lengthy but paints a good picture of reality.

If you are flying long distances alone and don't need the useful load, like speed, and want to stay in your budget you should take a look at the Mooney's. You can get one of a few models they have made since the 90's for well within your budget.

You should join AOPA and make use of their resources to get more information on owning and buying a plane. They have been a great resource in my recent plane search. They can give you a realistic idea on finance options as well as what your insurance rates are going to look like.

As for whats common (at least what I have seen) to some extent depends on your flight school and the quality of the planes. Many people do their VFR PPL in a rented plane (C172 or PA-28 being the most common). Then those that really like it and are serious about it look to buy an entry level plane to do the IFR in as well as build hours, get to know the national airspace system and just fly fly fly. Many buy what they trained in or step up a bit to something like an M20C or Arrow etc. Once they have their IFR the trips get bigger, longer and you really start to cross some distance. At this point you can expect anywhere from a few hundred hours to upwards of well more than that depending on how much spare time you have to fly around. Generally speaking most owners I have spoken to put about 100 hours on their plane every year (unless they use it actively for business).

To flat out answer the question, we must first say "it depends" but generally speaking I would say it will take you in the ball park of 300-500 hours to get into a high performance complex plane like a TTx or SR22 at least from what I have seen. Although to be honest some people train in an SR22 (see the above linked thread discussion, that guy trained in an SR22). The Malibu is a bit of a different beast and would take more time to get into. You can realistically fly 500 hours in 2 years if you fly ALOT, at a regular pace expect it to take 4 to 5 years to get to that point.

Legally, you can go buy an SR22 right now, pay a hefty insurance premium and do all your training in it. As long as you complete what ever the insurance company wants you to do, you can fly the plane. The broader question is "should you?..."

  At what point is it reasonable for me to safely and legally pilot
  these high performance planes?

The reality of this will come down largely to your insurance company and what they will allow you to fly for an affordable insurance premium. You list quite a range of planes here but generally if you want to fly high performance/complex airplanes your insurance company will look favorably if not mandate an instrument rating. For a turbine and or cabin class aircraft a commercial ticket wont hurt but is not necessary by any means. There will be some checkout hours required for any of these planes before you can fly them solo but the general expectation is that you are stepping up into them from another personal plane, or from a lot of hours in a rented plane. Most high performance newer aircraft will also sport a glass cockpit setup (G1000 or Avidyne etc). Insurance companies (and just common safety sense) will want to see some glass time if you plan on stepping into a plane like this.

Legally speaking you will need at least a PPL as well as a high performance endorsement (as all of these planes are over 200HP) and a complex endorsement for the Malibu as it has folding gear, moveable flaps and a variable pitch propellor. For a pressurized plane you will also need a high altitude check out.

  How would you suggest I get from newbie to mission capable?

The same way every pilot does, fly and fly often. There are no short cuts in aviation training. Nothing can replace time in the left seat. Plenty of people go from nothing to flying for the airlines in just a few years. However in that time they log a lot of hours (over 1500 to be exact) and they train in all kinds of scenarios.

The most important thing to keep in mind is to be patient, your PPL training will be hampered by weather, broken planes, busy instructors, delayed check rides and all sorts of things. This happens to everyone and you should not let it paint a negative picture for you or discourage you.


what is the disadvantage of blended wing body ,that they not used to achieve more than subsonic speed?

One of the few production designs that approaches a blended-wing-body was Lockheed Sr-71:

Surprise, with maximum Mach 3.2 it is also the fastest production aircraft ever built.

Because blended-wing-body does not have better L/D at low speed. But generating part of lift with the body has some advantage for high-speed aircraft as it allows smaller wings that is better for high speed (and worse for low-speed).


Why does the Canard Rotor Wing use a Canard?

The Canard rotor/wing demonstrator, later called the X-50 Dragonfly was a Stop-Rotor Rotary Wing Aircraft made by Boeing and DARPA to demonstrate the principle that a helicopter's rotor could be stopped in flight and act as a fixed wing (like in movie The Sixth Day).

Image from boeing.com

The canard is used in case of Boeing X-50 Dragonfly in order to overcome the transient aerodynamic loads that occurred during conversion from rotary to fixed-wing flight. During transition from rotary mode to fixed wing mode, the rotor is being unloaded and the aircraft has to produce enough lift. The designers used both a canard and horizontal stabilizer to overcome this problem.

From Canard Rotor/Wing Aircraft:

  During development, analysis and testing indicated that the X-wing design encountered high transient aerodynamic loads during the conversion from rotary to fixed-wing flight. The CRW design addresses this issue by generating positive lift on both the canard and horizontal tail during conversion. By deploying the flapped canard and the full-flying horizontal tail, enough lift can be produced to support the weight of the aircraft, and the main rotor can be completely unloaded throughout the conversion maneuver.

The aircraft never made a conversion flight and the program was canceled.


With larger wings comes more drag. True, because the drag is a function of the wing area A:
$$ D = C_D \cdot \frac {1}{2} \rho \cdot V^2 \cdot A $$
You need a certain wing area to support the weight of the aircraft. Now the question is: over how many wings will we distribute this wing area? For over 80 years, the answer has been: one wing (the two wing halves make up one wing).
The classical biplane is a thing of the past, however there have been incredibly clever aircraft builders who have looked at the long coupled canard configuration. This one really makes a lot of sense:
 Image source
So to answer your question: there are aircraft with two wings. It's just that people don't buy them, and go for boring old Cessna's instead.


Why was the A380 built with a gull-wing design?

The wings are designed like that. You can see them in the picture below.

Image from airliners.net

The A380 wings are designed to be the most efficient while still inside the 80m 'box' for efficient airport operations. The result is a clean slate design which used CFD extensively to get the most efficient aerodynamic design possible.
The 'curve' near the root means that the landing gear in the wings could be as short as possible while being long enough to prevent a tail strike during rotation and allowing the spar to pass below the floor.
The shape also allows enough ground clearance for the inboard engines. This assumes importance with the advent of engines with ever higher bypass ratios.
Of course, the use of modern composite materials means the the wing 'flexes' up to be more or less straight once the aircraft is airborne.

(wikimedia.org) In-flight 'flex'.


I don't know about a formal structure, but ground to air and air to ground communications usually follow the 3-W or the 4-W rule.

For air to ground communication - use the 4-W rule:

Who the controller is (identification of the controlling agency)
Who you are (Aircraft Identification)
Where you are (what is you position and altitude)
What do you want (state your intentions or request)

Example:

Grand Junction Approach, Cessna one seven two Sierra Papa, five miles southwest of the ABC VORTAC at five thousand, five hundred, inbound for Grand Junction to land with ATIS Kilo.

Here the pilot identifies himself as a Cessna with the identification N172SP, that he is five miles southwest of the ABC VORTAC at 5,500 ft MSL, and that he intends to land at Grand Junction airport and has the latest ATIS weather report for Grand Junction.

ARTCC and other air traffic controllers will generally use the 3-Ws to communicate with you

Who you are (the aircraft they are giving their instructions to)
Who they are (the name of the controlling agency)
What they want you to do (instructions for the aircraft in question to follow)

Example:

Cessna one seven two Sierra Papa, Grand Junction Approach, turn right to 030.  Descent and maintain three thousand two hundred.  Expect vectors for runway three zero left.  Squawk six four one one and ident.

Here the controller (Grand Junction approach) has advised Cessna 172SP to turn to a heading of 030 and to descend to 3,200 ft MSL.  He should also expect further heading instructions for insertion into traffic for runway 30L at Grand Junction airport.  The controller also tells the pilot to set his transponder to the code 6411 and ident, so the controller can verify his position.

As a courtesy, and often requested or implied by controllers to verify the pilot in question heard the instructions and will comply, the pilot will read back the instruction in full to the controller, followed by his/her callsign.

Example:

Right to 030, descend and maintain three thousand two hundred, expect vectors for runway three zero left, squawk six four one one and ident, Cessna one seven two Sierra Papa.

The NATO phonetic alphabet will be used for individual letters to avoid confusion by both parties as many letters can sound similar on a garbled radio transmission. Other oddities include the use of the word 'niner' in place of the number 9; This is to distinguish from the number 5, which is pronouced "fife".

English is also the accepted international language for use in flying and radio communications, but is only required for flights under instrument flight rules (IFR).


How do aircraft stall warning systems handle (or not) asymmetric-stall situations?

They don't.  The Stall Protection Computer only considers overall body AOA as measured by vanes on the left and right side of the nose.  AOA is just one bit of data, and the SPC also is measuring G loads, yaw rates, speed wise acceleration or deceleration, pitch rates, etc. and also getting inputs on flap/slat position etc to allow for all those effects.  It computes a solution for presenting the barber pole on the speed tape, and the shaker and pusher (if installed) firing points based on the body AOA and all those other factors, not local wing AOA.

If you yaw a swept wing jet really hard with rudder, it will roll on its back, stalled or not, just from the asymmetric lift with the sweep (full aileron may or may not be enough to counteract it - you learn this the first time you do a V1 cut in training).

In any case you don't normally touch the rudder pedals on a jet except during takeoff and landing or if an engine quits.  Yawing the plane also makes the vanes show radically different angles because of the changes in airflow around the nose when skidding or slipping, and you will get some kind of mismatch related error message.

On a jet with heated leading edges, if you had ice on the wings, the SPC will be fooled and can't account for this, and the wing will stall at a lower AOA than the SPC's computed solution and the airplane may depart when the barber pole still shows good margin, and before the shaker goes off.  A nasty surprise.  Ice on one wing and not the other just means when it goes, before shaker, it will roll really hard.


How are unpaved strips created and maintained?

Advisory Circular (AC) 300-004 from Transport Canada has detailed information regarding the maintenance of unpaved runways.

  The purpose of this document is to outline methodologies for the
  measurement and reporting of surface shear strength for unpaved
  runways.  In addition, the document outlines recommended practices for
  condition inspection, maintenance and repair of airport gravel
  surfaces and turf landing strips.

Runways should be designed with consideration for drainage (slope, crown, etc), susceptibility to frost heave, vegetation, roughness, etc.

Maintenance can be based on surface hardness measurements made with a penetrometer. A schedule for periodic inspection is created when the runway is new. The AC recommends a maximum of three years between hardness measurements. One type of penetrometer measurement is described as follows:

  The Boeing High Load Penetrometer (Reference Boeing Document No. D6-24555 - High Load Penetrometer Soil Strength Tester) consists of a hydraulic cylinder with a cone point test probe mounted at the rod end.  The hydraulic cylinder is normally positioned against the frame of a heavy vehicle which serves as a reactive load.  In the test procedure, the probe is driven at a steady rate to a 100 mm (4 inch) depth into the surface by the application of pressure through a hand pump.    Generally a pressure reading is taken about 30 seconds or less after movement of the penetrometer has stopped at the 100 mm (4 inch) depth.

Once maintenance is deemed to be required...

  Gravel pavement surface maintenance primarily involves periodic
  grading to remove the surface irregularities developing with time and
  to re-establish grades for drainage purposes. Occasionally, new gravel
  has to be added to replace lost material.  Dust suppression measures
  may also be needed during the summer months.

The recommended aggregate sizes are shown in this table from the AC:

The recommended grading method is shown here:

Also note a wealth of information in the reference documents listed in section 2.1 of the AC.

This presentation (.pdf link) from a company that provides airport maintenance services has additionl useful information and photos.


Could a tail rotor serve as a spin breaker for winged aircraft?

At least one of two possible devices is regularly added before spin testing:

Jettisonable mass, for example by fixing a sandbag to the tail, or
a spin chute.

Spin chutes do what you propose in yaw, but what they mostly do is to pull the tail up so the angle of attack over the whole wing is reduced. This is equally achieved by jettisoning that extra mass at the tail: Now the more forward center of gravity will add a nose-down moment.

In both cases the lowered angle of attack restores roll damping on the wing. This is really what stops a spin, yaw is less of a problem here.


In the U.S., Is it ever legal for an aircraft to occupy the runway turnaround area while another is taking off or landing?

Jim's answer is accurate. Unless there is a proper boundary between the turnaround and the runway, an aircraft should not be there while other aircraft are landing or taking off.

In the FAA's AC about airport design:

  Obstacle Free Zone (OFZ). The OFZ is the three-dimensional airspace along the runway and extended runway centerline that is required to be clear of obstacles for protection for aircraft landing or taking off from the runway and for missed approaches.

The dimensions of the zone are different depending on the aircraft size and approach minimums. Specifically the runway OFZ has widths from 120 to 400 feet. This is the zone typically protected by the hold lines (pictured in Jim's answer), which are typically placed to provide adequate separation for the worst anticipated case at that airport.

Regarding the edge markings, they should be parallel to each other and not follow the edge of a turnaround pad. From the AC on airport markings:

  When a taxiway connects to a runway or the runway has turn pads or turnarounds, the runway edge marking remains continuous between the runway and these adjoining infrastructures.

If the turnaround pad is designed to be occupied while the runway is in use, this is referred to as a holding bay. A proper holding bay would look like this:

This illustration comes from the airport design AC. Notice that the FAA considers this poor, because it provides no guidance such as taxiway center lines for pilots to follow.


How do manufacturers/kit providers determine Vne?

$V_{ne}$ is typically set to about 90% of $V_D$, the maximum design dive speed.  This difference provides a safety margin.  Above $V_D$, damage may occur due to flutter or structural failure, or controllability considerations may make the aircraft unflyable.  The aircraft is not guaranteed to fall apart at $V_D$ due to additional structural and manufacturing margins.

During flight test, the aircraft is flown above $V_{ne}$, up to, or close to, $V_D$.  Appropriate safety precautions are taken, e.g. parachute.  Any failure below $V_D$ indicates a design or manufacturing issue that must be resolved prior to certification.

The limitation to flight below $V_{ne}$ (as opposed to $V_D$) during regular operations provides protection against airspeed measurement errors, pilot errors and some margin against structural degradation over the lifetime of the aircraft.


Why separate autopilot controls for course and heading?

First, I'll try for the 50 words or less: Course is the line across the ground that you want to go. Heading is where you have to point the aircraft to fly that line.

That's less than 50 words, but I'm not sure it's any better.

Let's look at the obvious first. Let's say, over a short distance, you want to fly a course of 270 degrees true. If you fly the airplane on a heading of 270 degrees, you will fly that course ONLY if there is no wind, which for all practical purposes is never the case. If there was a wind from the north, you would have to maintain a heading greater than 270 degrees to make good a course of 270 degrees.

Actually, you can never say that the course between point A and point B is a single value in degrees unless those two points are very close together. If you draw a line between point A and point B and those two points are not close together, and then measure the course leaving point A (the angle between north and the line as it leaves point A) you will find that it is different from the course as you arrive at point B.

You can, however, tell the autopilot to fly a direct course from point A to point B and it will do it, changing the heading as necessary to account for the wind and fly that course.

So, why does an autopilot need to have a "course" function and a "heading" function. In my experience, the greatest single use of the heading function is when a controller is vectoring you and tells you to fly heading so and so. The second is when a reroute from your existing course is necessary, and you use the heading function to keep the airplane going straight ahead for a bit while you redo the revised course setting you want to use.

If you forget to again use the course function after putting in the revised course, the airplane will continue on the heading it was on while you were updating the course, and you will shortly be off course. That mistake has been responsible for aircraft being hundreds of miles off course.

During the first Gulf War, I heard a Canadian controller inform a USAF aircraft that they were over 300 miles off course when Canadian radar picked them up prior to landfall coming in from Europe.

A captain at the first 747 carrier I flew for got over 50 miles off course and was demoted to First Officer. He had forgotten to switch from the heading function to the course function.

Finally, as an added problem, if you choose to define your course in degrees magnetic, you must also account for the change in magnetic variation as you proceed along that course.

Insofar as item 4 is concerned, you (or the autopilot) is going to change heading as necessary to keep the airplane proceeding along the course as defined by the runway centerline. There's a bit of confusion of terms here in that runway directions are typically referred to as the runway heading rather than the runway course.


Can normal PC headsets replace 'aviation' headsets?

Can you physically make it work? Yes. But you have to have an adaptor that fixes several compatibility issues.

Headphone impedance

Impedance is usually referred to in high and low range. Military headphones are low impedance, 19$\Omega$. Civil aviation uses 300$\Omega$, high impedance headphones. Impedance matching is not vital, but can cause some problems with sound quality. Using a low-Z headset with a high-Z output can cause distortion. A low-Z headset will also be more sensitive, so you would have to turn the volume down. You could run the risk of damaging the headset or your hearing if you have the volume up too far. The headphones you listed in the question are 60$\Omega$, which is somewhat of an in-between. There's no real standard, but low-Z are usually less than 32$\Omega$ And high-Z is usually above 100$\Omega$.

In the recording studio we considered high-Z headsets to be "universal" meaning that you could plug them in anywhere and they would work, but might be limited in volume. I used a set of low-z phones, since I could plug them into a line output and actually hear it. I was always careful to make sure volumes were turned down before I plugged them into the com boxes. They were pretty sensitive.

Microphone impedance

This will make a bigger difference than the headphones. Military systems use 5$\Omega$, low impedance mics. Civilian systems use high-Z, 80-300$\Omega$ amplified electret Mics. The headset you listed in the question lists 2.2k$\Omega$ which would be work, depending on how much amplification it has. Aircraft coms use a vox circuit to cut out noise that opens when you speak. Depending on whether there is a way to adjust the mic input the level may be too much or too little for the vox system. Too little and it won't open when you speak, too low and it will stay open and you will hear all the aircraft noise.

Phantom power

Electret mics require a power source to operate. They can either contain a battery or run off phantom power, which is a voltage supplied by the device it's plugged into. Some aircraft intercoms provide phantom power. I'm unable to find any standard voltage, but it appears the David Clark aviation headsets run on 8-16v. The standard voltage from a PC audio card is 5v. The headset you listed in the question shows that it requires 2v. I presume that, since it's made for PC use it's intended for 5v, but will operate as low as 2v. There's no way to know if 8-16v would overload it, so you would have to either adapt the phantom power or run it on a battery.

Connectors

Aviation mics have different physical plugs.

Most commonly the headset itself uses a 1/4" phono plug, wired the same way as older audio headsets with 1/4" plugs.

The microphones in aviation headsets are seperate and use a somewhat aviation-specific .206" TRS plug.

Helicopters and military aircraft use a completely different .281" TRRS plug for both headset and mic.

Airbus uses a 5-pin XLR connector for both mic and headset.

Judging from the fact that people have schematics posted on the web on how to adapt aviation headphones for non-aviation use, but not the other way around I would speculate that even the best non-av sets don't meet the challenges of aviation. Some of the physical design characteristics, such as the pressure exerted on the head pads, etc. are probably quite different from the non-av sets.

If you look at prices, aviation headsets run well more than twice the price of equivalent quality non-av sets. I'm sure some of that extra price is in design characteristics of the av sets. But, I also suspect that manufacturers will take the exact same sets, change a couple of resistors, put different connectors on them, add the word "aviation" to the box then add $500 to the price.

Images source

Aviation data found at Acousticon website


What experimental techniques should one employ during cruise flight to determine correct airspeed to fly for max range in a headwind or tailwind?

An old technique is "Half the Headwind, all the Tailwind".

So if you're flying into a headwind of 20kts, increase your cruise speed by 10kts. If it's a 20kt tailwind, decrease your Cruise Speed by 20kts (but only as far as BestEnduranceSpeed).


Indeed, it is due to resemblance with Greek letter 'lambda', though not the capital one ($ \Lambda $), but the small one: $ \lambda $.

I am attaching a pic of X-45 with me drawing a lambda over it. Typically, the wing has two taper ratios. The inboard wing tapers heavily, corresponding to legs of small lambda, and the outboard wing tapers slightly or do not taper at all.

Other examples include B-2 bomber:


When do airline pilots arrive at airport?

Airline pilots generally arrive at the airport 2 hours before departure.

Typically, a pilot will gather in a meeting with other pilots flying the same flight (who he/she may have never met before; but that is not a problem as there are Standard Operational Procedures which every pilot follow). They will discuss the flight plan (including expected delays, departure / arrival routes and procedures), weather, review the loading sheet & fuel etc.

After the pilots' meeting, they will also meet the flight crew and have a brief discussion about the flight. Matters such as expected delays, transport of patient (sick passengers) needing medical attention etc. will also be brought out.

Around 30~45 minutes before departure, the pilots will board the plane. One pilot will program the Flight Management Computer in the cockpit while the other will conduct a walk-around.

There are "stand-by" pilots ready to takeover whoever is unable to report to duty at the airport. They can be anywhere and doing anything while on call, however they must be able to arrive at the airport typically 1~2 hours after receiving a call. Also, they must not consume alcohol while on call as this will invalidate their flying status.


What factors come into play when reducing the total noise generated by a helicopter?

I'm no expert but the RAH-66 Comanche can help answer your question.

It was a stealth attack helicopter prototype.

The Wikipedia page lists two main design elements:

A five bladed rotor, the more blades you have, the slower they'll turn, so less noise. Of course they are harder to balance, so it's not cheap.
Canted blades, kind of like winglets. They reduce the blade-tip vortices. The intricate shaping also is expensive, as the blades were 100% composite.

Sound proofing the engine compartment and muffling the exhaust can be expected as well. But that's added weight.


Why are planes flying in a zigzag path over Long Island when approaching JFK?

There are 3 STARs (Standard Terminal Arrival Routes) into JFK that cross over Long Island:

PARCH 3 RNAV ARR:

PAWLING 2 ARR:

ROBER 2 ARR:

(Jeppesen charts)

None of these have particularly pronounced zigzag patterns, so what you describe is probably not coming from the waypoints of the arrival procedure.

Looking at flightradar24.com, we can currently see BAW1 approaching JFK:

This already looks a bit more like a zigzag. It would seem they are arriving on the PARCH3 or ROBER2 until ROBER and then received radar vectors onto final approach for runway 31L/R. These vectors are typically given by ATC (Air Traffic Control) for spacing reasons.

When going back to yesterday evening using flightradar24's Playback feature, one finds much more pronounced turns over Long Island (thanks to ymb1 for suggesting this):

Here, aircraft are approaching runways 22L/R. You can see that there are also aircraft from the South and West joining the queue to land and ATC needs to make sure there is enough separation between the aircraft. The easiest way to achieve this is by instructing them to fly in a certain direction ("radar vectors") until there is enough space to fit them into the queue, which results in such a zigzag pattern.

Such turns can also be more localized than shown here. See e.g. Why did my LGA-ORD flight make an S-shaped turn round the time it was passing a storm?, where a flight into Chicago made an S-shaped turn during the descent, which would also feel like a zigzag. Such instructions can also be given to aircraft while they are still flying on the STAR over Long Island, especially when there is a lot of traffic during peak hours.


Normally, the airflow over the vertical stabilizer is from front to back, which means it hits the front face of the rudder, and acts to centre it. But the vertical stabilizer is actually like a small wing. In a sideslip, the airflow comes more from the side. If you're slipping tail-right, using left rudder, the airflow comes from the right. When the vertical stabilizer stalls, the airflow is no longer acting to centre the rudder: it's just pushing against it, and pushing it away from the centre.


Seaplanes mostly have water rudders that are used at lower speeds and are retractable (actually, they tilt out of the water flow).  At higher speeds, like takeoff runs and landings, high speed taxis, they are retracted and the primary means of steering is the plane's rudder.  Water rudders are connected to the regular rudder pedals.

Airlerons can also be used to steer a seaplane on the water by creating differential lift and drag (since most ailerons don't deflect symmetrically).

Doors can be used to steer by opening one or the other, creating drag on one side or the other.  I have seen a C-150 pilot do this in the air, as well.  Flaps, which create symmetrical drag, can be used to assist in slowing down but they're not useful for steering.

Seaplanes have no brakes other than the drag of the floats in the water, so a seaplane pilot won't approach a dock at a perpendicular angle.  Instead, they will land along side a dock and then jump out onto a float and then to the dock, rope in hand.

Seaplane pilots also carry oars, which allow them, yes, to paddle, steer, and stop the plane.

So seaplane pilots have a number of tools at their disposal to steer the plane on the water. You can also read through the FAA Handbook for seaplane operations.

It does require some coordination!


Do airline pilots use FD when performing visual landing?

This answer will be quite anecdotal (I have not seen a survey on the question). It will answer the question for "most people I've worked with", and for "my" aircraft (B737NG). Also, the usual disclaimer: different airlines/aircraft manufacturers may have different SOPs/instructions/limitations. Consult your manuals.

In general: most pilots will leave FD on, IF it still provides useful and reliable information, without being an obstruction/nuisance (i.e. when configuring it to give correct guidance would be more trouble than it's worth, given that you already have visual references). This philosophy is also usually what you'll find in an airline SOP, but in more formal language.

I'll try to provide some examples (non-exhaustive) to illustrate this depending on how you were set up before being cleared for the visual approach:

ILS to straight in landing

Leave the FD on until landing (on my aircraft, B737NG, it will disappear at 50 ft RA), both localizer and glideslope will give usable and reliable information to the FD. (Caveat: in visual conditions, ATC might be less strict about avoiding signal interference. They might for instance let an aircraft on the ground taxi to cross your runway while you're on approach, which could cause localizer/glideslope interference).

ILS to sidestep

Most would turn the FD's off. Both localizer guidance and glideslope guidance will be to the "wrong" runway. The FD is likely to be more of a nuisance than a useful tool.

Non-ILS approaches with no centerline offset

The Localizer/LNAV path will give good lateral guidance to the FD. The vertical guidance will depend on the approach and your equipment. If the aircraft generates a good quality vertical path, which crosses the runway threshold at a reasonable height (50 ft), there is no real good reason to turn the FD's off. If all you have is vertical speed (V/S) guidance, it might be more helpful to turn FD's off.

Non-ILS approaches with centerline offset (for example most VOR approaches)

At some point during the approach, you'll want to abandon the approach course, and line up with the runway. Where this point occurs depends on specific approach, and how you intend to fly it.

Example: A VOR approach to runway 36 (runway heading 000) might use a VOR 1 nm east of the runway with inbound course 005. You might want to stay on the inbound course of the VOR until it crosses the extended runway centerline. In this case, most people would keep the FD on until reaching this point, and then turn it off, as it won't give you any useful guidance afterwards.


How does an API (air position indicator) work?

The API uses not only heading and airspeed but they are fed to mechanisms within the instrument that solve the navigation problem using sine, cosine and secant functions. The output was latitude and longitude from the departure or a known fix (geographical position) to give the no wind position of the airplane. This was then used by the navigator to give a dedreconing position by plotting the last known wind vector from the no wind position.


Why is polar curve of a glider dependent on flight load?

Oh god- I made a terrible mistake: While $C_{lift}$ and $C_{drag}$ are really independent on weight, this is (of course..) not the case for the velocity polar curve. The two curves scale perfectly with weight and are just subject to a simple transformation. No magic behind and completely transparent.

Sorry: Question Solved ;-)


Where should the support points be for testing a model wing in a wind tunnel?

Indeed, the Reynolds and Mach numbers should be the same, or at least similar to the actual aircraft, depending on what you want to measure. For instance, the maximum lift coefficient is very sensitive w.r.t. Re and if you add a Mach number above 0.3, compressibility needs to be taken into account as well (even though quite good correction models exist for this). On the other hand, if you want to measure for instance only the zero-lift angle of attack, the Re doesn't matter much.

Anyway, where you support the airfoil doesn't change the Reynolds or mach numbers. In fact, you can theoretically support it at any point. The lift and drag will always be the same for every point; what changes is the moment that you measure. It might be convenient to choose the aerodynamic center which typically lies at around 25% of the chord, since there the pitching moment doesn't change with angle of attack. But be aware that this location can still very slightly move with AOA in practice. For more information: https://en.wikipedia.org/wiki/Aerodynamic_center.


Are the GPWS callouts recorded with real people or computer generated?

Since the callouts are "fixed" and don't change it's easier and cheaper to design, manufacture, and certify the system using recorded voices. For each one, the software just needs to play the appropriate audio file.

I used to work on TCAS and the callouts were all just .wav files. Sometimes companies will hire voice actors (or subcontract to a recording company). We had an employee record the files.

Computer generated voice is useful where the content is highly variable such as the D-ATIS. (I know, it's a ground system but the concept applies.)


How to find if an aircraft is inside an airspace using latitude and longitude?

It is just a well-known computational geometry problem called PIP (point-in-polygon). I assume that the airspace is pretty small, and we can consider its boundaries as lines (not curves) in a plane.

Firstly convert latitude and longitude minutes and seconds to fractions. Then use any of PIP algorithms (or libraries, if you do it in any programming language).

For more information check: wiki or this link.

You can also use WolframAlpha for that, or any programming language with a specific library (for example, OpenCV does it very well in C++ or python).


Is low pressure compressor air used to cool turbine blades?

Short answer:

Low pressure compressor air can be used for turbine cooling, but usually it can only be used to cool the low pressure turbine. For the HPT, you need cooling air from the HPC. This is because the cooling air must come from a location in the compressor that is a higher pressure than the part of turbine it is cooling, so it will actually flow into that turbine location.

Longer answer:

Cooling air from the compressor is air that the engine has compressed, so put energy into, but doesn’t get the full energy out of, when it enters the turbine as cooling air. So, you want to use as little as possible, and take it from the early stages of the compressor, rather than the back of the compressor, where even more energy has been put into it.

But.... the cooling air has to be taken from a location within the compressor that is a higher pressure than the turbine location which it is cooling, so that it actually flows into the turbine.

Hence, to reduce the parasitic nature of cooling air, the low pressure turbine is generally cooled with air from the early stages of the compressor, but the high pressure turbine must use cooling air from a sufficiently high source, so it usually comes from the last few stages of the high pressure compressor. As explained, this is necessary for the pressures to be favorable to cause the cooling air to flow. However, aside from meaning it is more parasitic towards the engine, there is another disadvantage of having to use high pressure air for cooling. Pressuring the air causes its temperature to increase. So, the “cooling” air from the exit of the high pressure compressor is hotter than cooling air from the start of the HPC. Because of this, sometimes the cooling air is cooled by a heat exchanger in the bypass duct, because the cooling air from the exit of the HPC is actually quite hot.

Why the picture shows both LP and HP air in the same blade:

In the picture you show, the same blade is being cooled by both LP and HP air. This appears to contradict this answer. If one can use cooler LP air, why use the hotter, more parasitic HP air. I found the source of your image, and the text there doesn’t explain this contradiction. But if you look at the two images attached, you can see that the pressure around a turbine blade is not uniform. There are higher pressure regions especially at the front of the blade, while the pressure at the trailing edge is lower. Since you always need your cooling air to have a higher pressure then the static pressure at the location of your outlet, you need high pressure cooling air at the front where the pressure on the blade is high and you can get away with using lower pressure cooling air at the back since the pressure on the blades trailing edge is low.


How can a passenger determine airspeed without a handheld GPS?

It is impossible for a passenger to determine the airspeed to any reasonable accuracy (otherwise Birgenair 301 and Aeroperu 603 would not have crashed).

From my personal experience, it is not possible to receive GPS signal using a handheld-device in the passenger cabin. Even if it works, winds aloft at cruising altitude are often in the range of 100~200 knots. That throws the calculation completely off even if ground speed is known.

The only reliable way is to refer to the entertainment system, which obtains its data from the cockpit and is therefore accurate. However, the interface is usually programmed to display measurements in other units; the indicated airspeed has to be calculated from the displayed values manually.

Here are some ways you can guess the airspeed to a certain extent:

If you do not notice any significant airframe vibration, you can
assume the airspeed is somewhere between the stall speed and the max
airspeed.
If you can tell the flaps position from observation, you can also correlate that with the usual flaps extension speed of the model
you're flying, which should give you ~20 knots of accuracy.
If you are familiar with the SID or STAR of the airport, and you know planes normally pass a certain point at a certain speed.
If you have a handheld ATC receiver, sometimes ATC will issue speed instructions to planes during approach.


Is there any benefit to folding wings on commercial aircraft?

It would allow an aircraft to have a wingspan of >80 meters yet still be able to be serviced at a standard airport gate.

There are a variety of benefits to longer wingspan, but the major drawback is that commercial passenger airports are designed around that 80 meter box.