Is solar power used (as auxiliary power) on commercial aircraft?

The sun's energy is a max of about 1000 W/m2 at sea level (sun directly overhead, clear day). A solar power installation may have around 15% efficiency, yielding a max of 150 W/m2. Let's just see roughly what that gives us for a 737, to see if it's even that much.

The wing area of a 737 is 124 m^2, and the fuselage is 42 m long and 3.76 m wide. This gives a total area of 280 m2 if the sun is directly overhead. Covering all of this with solar panels gives a total (extremely optimistic) output of 42,375 W. The fuselage tapers at both ends though,  and needs to have openings for the windows, antennas, etc. The wings will probably only have the fixed panels covered in solar panels (not flaps, slats, etc) so you would be looking at significantly less for a realistic installation. The Solar Impulse 1 was in the same ballpark (200 m2 for a peak of 45 kW).

The APU on a 737 is rated at 90 kVA. Of course you will usually use less than that, but we are looking at solar only providing maybe 20% of the capacity for any considerable part of the day. Since solar is not always available, you cannot even downsize the APU.

Another important function of the APU is to provide bleed air. This can be used to run the air conditioning packs and to start the engines. Photovoltaic panels would be a very inefficient way to provide bleed air.

An airplane will probably look strange being covered in solar panels, but covering so much area also causes some issues. Inspecting the aircraft for damage will be difficult. This means the solar installation should be easily removable (also for repairing damage to the solar cells), and the structure may need to be more damage tolerant. The panels would also need to be attached well so that they would not depart the plane even if damaged. This all adds more weight.

You would be adding a lot of weight to install solar that only helps a little bit sometimes. You may get a small benefit by reducing the generator load on the engines, but probably not nearly enough to make up for the increase in weight.

Airlines are big on reducing fuel usage, and are willing to add weight to save fuel overall (such as with winglets), but we haven't seen solar put to use on any airliners yet. The most efficient way overall to provide regular power is to extract it from the engines that are already running. For auxiliary power, a small turbine generator, which can provide both bleed air and electricity. And for emergencies, a RAT.


Why was Air India flight AI101 diverted to SHJ 5 times in the past few days?

Is it possible that they don't have the range to get to JFK without stopping for fuel due to the Pakistan Airspace Closures/Restrictions. Looking at the dates, it seems that the flights started diverting when the India/Pakistan tensions flared up a week ago (~Feb 28).

https://www.flightradar24.com/blog/tensions-between-india-and-pakistan-affect-air-traffic/

Going to Sharjah for the diversion avoids the Pakistani airspace as seen below:

https://www.flightradar24.com/data/flights/ai101#1fb4a663


What name is given to an abeam waypoint in the FMS?

From the Thales Pilot Guide:

  If ABEAM PTS are desired:
  ABEAM PTS [3R] .......... Confirm/Press
  If Option 1 is defaulted, ABEAM PTS is displayed yellow, if not press [3R].

  ND shows direct track (dashed yellow), as entered, superimposed on existing ACTIVE F-PLN.
  Abeam WPTs are named ABxxxxx, xxxxx representing the first five characters of the relative WPTs.
  Ex: ABADAIB, ABBOKNO, ABDEVRO

Honeywell FMS is different:

  Abeam Points (ABEAM PTS)

  Push -

  creates place bearing distance waypoint on the Direct To leg abeam
  the bypassed waypoint if the bypassed waypoint was a database
  airport, navaid, NDB, or waypoint
  creates latitude/longitude waypoint on the Direct To leg abeam the
  bypassed waypoint if the bypassed waypoint was a
  latitude/longitude waypoint

So in the Honeywell FMS the abeam points will use the Place Bearing Distance name or the Lat/Lon name depending on the type of original waypoint.


Pitch control of tailless aircraft/flying wings with very wide elevons

Specifically, the simulation suggests to me that a flying wing (or any
tailless aircraft) with two single elevons along the whole of the two
trailing edges is not controllable.

This is certainly not true.  Many radio-controlled model airplanes and gliders with an all-wing, chevron-shaped configuration and no tail have this exact configuration of the elevons, which are the sole control surfaces.

For example, in the photo above, the elevons are red.
Google "Zagi flying wing" for many more examples.

If the elevons are deflected to pitch up, for example, it generates
negative lift over both wings and the torque (assuming CoG is ahead of
CoL) pitches the aircraft up.

This is not true either.  When flying a wing like this, an aft stick input generates a nose-up pitch torque that increases the angle-of-attack of the wing.  In the long run, the wing's lift coefficient is increased, not decreased.  There is no visible evidence of even a temporary tendency for the aircraft to "settle" (accelerate downwards) when the elevons are first deflected upwards, before the wing has had time to rotate to a higher angle-of-attack, though in theory this tendency must exist to some slight degree due to a temporary decrease in the wing's lift coefficient (but not to the extent that it actually becomes negative).  This "settling" tendency might be more significant if the aircraft's pitch rotational inertia were greater.
Conceptually, this is no different than the idea that when we are flying a "conventionally" shaped aircraft, and we move the control stick aft, there must some temporary "settling" tendency (downward acceleration) due to the fact that we've increased the downforce (or in some cases, decreased the upforce) generated by the tail, so the net upward lift generated by the aircraft is now less than weight.  Of course, this situation only persists until the aircraft rotates in the nose-up direction enough to increase the angle-of-attack of the wing sufficiently to bring everything back into balance, at a higher angle-of-attack and lower airspeed than were present initially.  In actual practice, this "settling" tendency is almost always so negligible as to be undetectable.
It might help you understand what is going on if you were to consider reflexed airfoils.  In such an airfoil, the trailing edge of the airfoil is permanently "bent" upwards, contributing a nose-up pitch torque, yet the airfoil still creates positive lift over a wide range of angles-of-attack.
For example:

(Source: https://www.diva-portal.org/smash/get/diva2:450812/FULLTEXT01.pdf )
It appears you are getting into trouble by relying on the idea that the Center of Lift is behind the Center of Gravity.  In reality, the Center of Pressure is not fixed, and in steady-state flight, the Center of Pressure (of the whole aircraft including the contribution from the elevons) and the Center of Gravity must coincide.  When we raise the elevons to create a nose-up pitch torque, this pitch torque can be conceptualized as a forward shift of the Center of Pressure.  Then when the wing rotates to a higher angle-of-attack, the Center of Pressure moves back aft until it coincides with the CG again, and the aircraft ends up in steady-state flight at a higher angle-of-attack and higher lift coefficient and lower airspeed than it started with.
A more modern way to think about aerodynamic forces and torques is to view the aircraft as having an Aerodynamic Center that is fixed at the quarter-chord point of the airfoil, plus a pitching moment coefficient that varies according to the shape of the airfoil.  With this convention, the lift vector can be viewed as acting at the Aerodynamic Center, but we also have to consider the effect of the pitching moment coefficent.  Raising the elevons shifts the pitching moment coefficient in the nose-up direction, as well creating some decrease in the lift coefficient.  A symmetrical airfoil has a pitching moment coefficent of zero, and conventionally shaped cambered airfoil with no reflex has a nose-down pitching moment coefficient.


Is it possible for crew oxygen to exacerbate a flight deck fire?

Wouldn't [a] descent to an altitude where you no longer have to use oxygen might be quite an important priority in the event of a [flight deck] fire?

It is an important priority. Below is the first page of the procedure for the Airbus A320:

Going through the procedure, if things got out of hand, there is:

  At ANY TIME of the procedure, if situation becomes UNMANAGEABLE :
  IMMEDIATE LANDING............................CONSIDER

And even opening the cockpit window is an extreme option for smoke that is too much to be ventilated.

A note on the depressurized cabin/cockpit scenario: Since there is depressurization, any scenario where a hose leaks, the supply will quickly dissipate towards the pressurization leak source (and not saturate the cabin/cockpit). (It will also help dissipate any smoke.)

So it's the opposite, one would link pressurization with oxygen saturation.

One of the items on the smoke checklist is turning off the air supply systems (called PACKs) and using the manual system to deliberately depressurize the plane:

  PACK 1+2............................................................OFF
  MODE SEL..........................................................MAN
  MAN V/S CTL.............................................. FULL UP

"MAN V/S CTL" means "Manual Vertical Speed Control", basically how the cabin altitude (a pressurization term) is set. Full up means max positive rate, which will equalize the pressure with the outside – dumping pressurized air so to speak.


In the simplest of terms:

Suck - Air is sucked into the turbine. For efficiency reasons, most aircraft let some of that just pass through the outer part of the fan, rather than through the whole engine.
Squeeze - The compressor squeezes that air together to a high pressure. This helps with ignition.
Boom - Fuel is injected and ignited. As the air gets hot, it expands.
Blow - The hot air drives the low-pressure turbine (driving the whole shaft holding the engine together), sucking new air in, and is itself blown out the back.


Why does Beijing's new Daxing airport have so few gates?

Airports aren't built with the envisioned capacity in one go. They are built in stages. Just look at Dubai International for example, they're always expanding the concourses, etc.

For Daxing Airport, I found what looks like a master plan (outline for a project's major elements):

Source: kaskus.co.id

It shows more than one (at least two) main terminal buildings, land area for expansion that is serviced by taxiways and aprons, and even an additional runway to the west. There is also plenty of remote stands, which are appealing (cheaper) to low-cost carriers.


How can the 777X's longer wing reduce vortices?

So it can fit into standard size airport gates and taxiways.

One reason the A380 didn't see wider adoption was it exceeded the maximum wingspan that most airports are set up for, requiring airports to build special gates and widen taxiways to accommodate it... which is expensive so very few did that.

Even the airports that did make the A380 mods found that an A380 flight couldn't be rescheduled to any available gate, as they only modified a few berths for the wider wingspan.

By folding the wingtips, the 777-X gets the efficiency of a longer wing and wingtips, but doesn't require a wider than normal gate space and taxiway. It can use any airport that can handle commercial traffic, without requiring expensive changes to the airport.


I don't really know how civilian or military pilot training takes place in Tanzania, but I might recommend that you make a visit to a fixed base operator at a local airport there in Tanzania and talk with the staff about flight training.  They may be able to assist your further on that path.

A basic Google Search for Flight Training in Tanzania turned up this place.  I don't know how close you are to Dar es Salaam, but they do have a private flight school out there and could better assist you.

As for scholarships for flight training, check these guys out.

Oh, and these guys as well.

Good Luck with your training.


Could a plane land vertically in a strong headwind?

Yes.

I assume that you do not have a good understanding of aerodynamics.  I apologise if that is not the case.

The way to think about these sort of questions is to ask "does the aircraft know that it's moving in relation to the Earth".  The answer to this is "no".

The only thing that matters, and the only thing that the aircraft cares about is airflow (wind) over the wings.

Ignore all sorts of little side effects and imagine an aircraft needs 70 kph of wind over the wings to generate lift and stay afloat, straight and level.

Now, imagine the aircraft is flying along and you could somehow make the Earth disappear but leave behind gravity and the atmosphere.  What would happen to the plane?  Nothing!  It still has 70 kph of wind over the wings and it keeps flying.

Now put the Earth back.  It still keeps flying.

If the pilot reduces the power to 69 kph ("thrust X"), the force generated by lift pushing the aircraft up is a little less than that generated by gravity pulling the aircraft down and the craft will start to descend.  Eventually, it will land (assuming that you remembered to put the Earth back!).

So two scenarios.  First, one where the air is perfectly still and the thrust from the engine ("thrust Y") is pushing the aircraft forward at 70 kph.  Second, where the wind is blowing at 70 kph and thrust Y is such that the aircraft is stationary with respect to the Earth.  Again, the aircraft does not know, or care, that it is stationary with respect to the Earth, just that it has 70 kph of wind over the wings.

Modify the second scenario slightly so that the wind is now 69 kph. The aircraft moves forward at 1 kph. Again, the aircraft does not know, or care, that it is going fowards with respect to the Earth. The wind over the wings is still 70 kph (speed of wind, 69, plus speed of aircraft 1).

Reduce the thrust to X again and the aircraft will start to descend, and also become stationary.  Eventually, it will land with no forward or backward speed.

In reality, this would be almost impossible since the wind is never of a constant speed from a constant direction so little movements would always be taking place.

I have seen a video, which I can no longer find, of a bi-plane which took off into a strong wind, flew backwards down the runway and landed on a spot before the one it took off from.

This comes very close.  With just a little more wind, a vertical landing would have been possible.


Is it possible to fly using a small engine?

The short answer is yes you can use some cheaply available engines to achieve flight however you are presumably asking about things like small car engines or motorcycle engines etc. The issue you have here is that these engines are inherently different from a use case standpoint than your typical aircraft engine. Generally speaking, most car/motorcycle engines rev too high to be used in an aircraft, you actually want to lower the RPM, not raise it. You can read up on it here and here and here. You can pull it off with a stepper gear box (like a turbo prop uses) and it was even been done on a piston plane back in the 80's by Mooney. The other problem you will have with car engines is cooling them, generally cars are watercooled, something that adds a lot of weight and is not ideal for flight. A two stroke or other similar air cooled motorcycle/scooter engine may be a better thing to use.

Many small engines will produce more than enough horsepower to achieve flight. Keep in mind the early piper cubs only had 40HP which can be easily found in many 2 stroke engines.

Your best bet may be to look for a used VW bug engine as they are very similar to aircraft engines and even were used in some air frames at one point in history. Due to the cars high production numbers the engines are fairly easy to come by.

You did not list a jurisdiction in your question but the regulations and legislation on this change from place to place, so you may need to see what exactly you are allowed to do in your jurisdiction in relation to home built and experimental aircraft.


What licenses/endorsements or type ratings do you need to fly a fighter jet?

In the US, the FAA's requirements for obtaining authorization to fly former ,military aircraft is included in 8900.1 Volume 5, Chapter 9, Section 2.

It is quite lengthy and covers more than just former military aircraft. As others have pointed out, most of these aircraft do not have a Type Certificate. They normally have a Special Airworthiness Certificate in the category Experimental Aircraft  Exhibition. Requirements to fly the aircraft are spelled out in the aircraft's operating limitations which are issued with the Special Airworthiness Certificate.

From 8900.1:

  A.    Background. The FAA requires pilot authorizations to operate
  some aircraft in the experimental category, including some former
  military, all turbojet‑powered (for this section, all turbojet‑powered
  includes all turbofan‑powered), all rocket‑powered, and all large
  (over 12,500 pounds maximum gross takeoff weight (MGTOW)) aircraft,
  and any other aircraft requiring specific pilot skills. Examples of
  such models are the Northrop F‑5, Bell P‑63, MiG‑15, Ju‑52, Mi‑24, and
  the BD‑5J. The FAA also requires authorizations to act as PIC of large
  or turbojet‑powered aircraft undergoing type certification.

  1)    The requirement for an FAA authorization to act as PIC of
  certain experimental aircraft is contained in the FAA‑issued aircraft
  operating limitations. Pilots are required to comply with the
  FAA‑issued operating limitations by 14 CFR part 91, § 91.9(a).

  2)    Because these aircraft are not type certificated (TC), a type
  rating is not available. In the absence of type ratings for these
  aircraft, it is the FAA’s objective to ensure, for the pilots flying
  these aircraft, a level of safety and proficiency similar to what is
  available for an aircraft with a type rating.

The specific pilot requirements are also spelled out in the document:

  A.    Former Military Turbojet/Turboshaft‑Powered Aircraft. To be
  eligible for an authorization to act as PIC of a former military
  turbojet/turboshaft‑powered aircraft, an applicant must:

  1)    Possess at least a U.S. private pilot certificate with an
  appropriate category and class rating for the configuration of the
  aircraft;

  2)    Hold an instrument rating;

  3)    Possess at least a valid U.S. third‑class medical certificate or
  equivalent (U.S. Military Flight Medical or U.S. driver’s license in
  accordance with the FAA BasicMed process (pilots using BasicMed may
  not exceed 250 knots indicated airspeed (KIAS)));

  4)    Have logged a minimum of 500 hours of pilot flight time in the
  aircraft category and have completed the U.S. armed services
  qualification checkout described in this section; or have logged a
  minimum of 1,000 hours pilot flight time, including 500 hours as PIC
  in the aircraft category, and have completed the training requirements
  of this section; and

  5)    If the aircraft is capable of supersonic flight, have a minimum
  of 250 hours of pilot flight time as PIC of a fixed‑wing
  turbojet‑powered aircraft, in a Group V, VI, or VII aircraft (see
  Figure 5‑173), or present proof of completion of a U.S. military
  qualification in a supersonic turbojet‑powered aircraft.

  B.    Former Military Propeller‑Driven Airplane. To be eligible to
  serve as PIC of a former military propeller‑driven airplane that has a
  MGTOW exceeding 12,500 pounds, or which has a horsepower rating of
  more than 800 horsepower and a VNE that exceeds 250 knots, an
  applicant must:

  1)    Possess at least a U.S. private pilot certificate with an
  appropriate category and class rating;

  2)    Possess at least a valid U.S. third‑class medical certificate or
  equivalent (U.S. Military Flight Medical or U.S. driver’s license in
  accordance with the FAA BasicMed process (pilots using BasicMed may
  not operate an aircraft with a MGTOW above 6,000 pounds));

  3)    Have logged a minimum of 500 hours of pilot flight time; and

  4)    Have completed the training requirements of this section.

That last item can be a challenge as it requires finding someone with the proper authorization to provide the training.

More information is available at the FAA Vintage & Experimental Aircraft Program web page.


Did Pacific Southwest Airlines ever operate flights under VFR?

I was a controller at L.A. Center around that time, and it was extremely common for airlines on the short-haul routes to go VFR-on-top, which is VFR but on an IFR flight plan. There would have been a lot of downsides to flying VFR but every advantage to them to fly VFR on top: with on-top they didn't need clearance into class B (back then the TCA) or get refused or delayed because the controller was "too busy"; didn't have to fly airport patterns (basically guaranteed a straight-in since they would be on an instrument approach); and for flying into the metered airports like LAX or SFO they would have a guaranteed slot, unlike trying to call up as a VFR where they would go to the back of the line and might have to hold for an hour. Plus of course on-top has the benefits of not needing IFR separation, so ATC would almost always give them a direct routing and they could climb all the way up to 16500/17500 instead of being step-climbed under everyone else and capped at maybe 10,000.

So while I don't remember specific routine flights from 25+ years ago, I do remember working a LOT of airlines flying VFR on top on the short routes like LAX to Bakersfield, Burbank to Fresno, etc.


Why don't airplane turbo piston engines have boost control?

The majority of piston airplane engines are based on very old technology, before computerization was available. The vast majority of airplane piston engines are carbureted with manual mixture control, prop control and turbo control and the pilot has to manage all that plus carb heat manually.

New engine technology has been very slow to come into the piston market because certification costs are so high, and the market is so small. It would cost engine manufacturers millions to develop and certify new turbo-normalizing systems for these old engines and as there are probably only a few thousand turbo-normalized avgas piston airplanes in the world they would never recoup the costs.

There are modernized engines on the market with electronic fuel injection, computerized engine management with turbo-control, and single-level operation. These are slowly making inroads into the market but it's going to take time.


Why are expletives deleted in CVR transcripts?

[O]ughtn't authenticity outweigh relevance?

The goal of a CVR transcript is not to give an authentic account of what happened in a cockpit. It is to give a relevant account of what happened in the cockpit.

A typical investigation board (NTSB or equivalent) has a very specific goal: investigation what happened to prevent it from happening in the future. To demand exceedingly intrusive measures into the privacy of a pilot - like installing a number of microphones recording everything they say - safeguards are put in place (remember, in virtually all other sectors, an employer installing microphones in the workplace would rightfully face serious criminal charges).

For example,  the investigation typically explicitly excludes civil and criminal accountability questions. As additional guarantees to the privacy of the pilot, only a selected number of people get access to the original recordings, and they decide on the content of the transcript.

As their goal is to give a relevant account, not an authentic account, they can decide to withhold information that could be harmful to relatives (like the exact language used when their loved ones faced imminent death), if the information does not help in establishing the goal of preventing future accidents. Unless the expletive is pertinent to the investigation (for example, if it could be misheard as a specific command), it is left out.


Do airlines black-list certain movies on their inflight entertainment system?

The specific policies relating to in-flight entertainment are a matter for individual airlines. They will tailor content to the demographic of their typical passengers.

Air crashes and similar themes are almost universally avoided, but there are significant regional differences leading to films being more or less heavily censored, or simply not offered.

For example - airlines based in Muslim countries will censor references to pork and pork products, either by deleting the scenes, or editing the dialog, or both.

Europeans are tolerant of some nudity, but dislike excessive violence, while the Middle East will censor all sexual language and bare skin, but permit a much higher level of blood and gore.

Other, lower-level censorship may also occur. Logos of competing airlines can be pixelated or deleted.

This is important to airlines. In February 2013 a United Airlines flight was diverted because of a 'passenger incident' originating when parents complained about 'inappropriate content' for their young children (http://www.telegraph.co.uk/travel/travelnews/9973766/Sexually-explicit-in-flight-film-causes-plane-diversion.html)

Much of this information was sourced from CNN. Apply your own judgement when assessing the veracity of such a source.


There's an airfield somewhere in the United States with a metal runway. Where is it?

You are thinking of Bogue Field (KNJM). It is a Marine Corps auxiliary landing field, currently mocked up to look like a carrier deck, and last I heard it was still active and in use to practice carrier landings.

The runway surface is Perforated Steel Planking (PSP - actually I believe the new stuff isn't "steel" anymore but the name remains) - discrete sections that can be laid out to quickly construct temporary landing strips in forward combat zones.

A search on AirNav for "pierced steel plaking" came up with a couple more military fields:

KNXP   Twentynine Palms SELF Airport (Strategic Expeditionary Landing Field) -
Twentynine Palms, California, USA

2CA9   Castle Dome Army Heliport -
Yuma Proving Ground (Yuma), Arizona, USA

2CA9 says it's a helipad but it's 3000x65. The rest of the results were all (reasonably sized) helipads.


What sort of debris has been found in 737 Max fuel tanks?

As a generic answer, not unusual. Besides personal objects like bucking bars, clecos, rags and such left in tanks, the biggest contamination source, from my experience working on a production line many many years ago, is "swarf". Swarf is aluminum drill shavings and mountains of it are created during assembly.  You will also get wire cutoffs and other similar bits, shop (bucked) heads of rivets that were drilled and punched out because the rivet was dumped when being driven and had to be removed and reshot.

All that stuff is supposed to be thoroughly vacuumed out before the sealers go in with their goo guns, but nothing is ever perfect.  Even if the wing was cleaned out before the sealing was done, if the wings get modded or repaired farther down the line, where more rivets get drilled out and redone, more swarf or other contam gets introduced and may get overlooked.

The first time fuel flow test runs are done on the completed aircraft, that's when you find out how bad a job they are doing up the line as the fuel screens and filters are removed to check.

Some manufacturers will build special rotation fixtures to put the wing in (not really practical in a one piece swept wing, but easy to do with a straight one) after it comes out of the assembly jig to rotate, barbecue chicken style, while they listen for objects clattering about. It's good for catching bucking bars, clecos and such that get left inside.


How to trim in level flight when speed increases?

The angle of attack is lower for the faster flying aircraft. More speed means more dynamic pressure, and in order to create the same lift (weight did not change, after all), less angle of attack is needed to create the needed amount of lift.

Now it is important to know that the angle of attack (more precisely, the difference between the actual and the zero-lift angle of attack) on the wing is higher than on the tail if the aircraft is statically stable. If the aircraft accelerates, the relative amount of lift loss on the wing is less than on the tail, because both experience the same reduction in angle of attack. To keep the balance between both the same, this extra lift loss on the tail needs to be compensated by some downward elevator deflection. The center of gravity did not change, and the center of lift must be shifted to the same longitudinal station in order to maintain level flight.

Fun fact: When transitioning from sub- to supersonic speed, the elevator must be trimmed trailing-edge-up, because now the center of pressure moves back on both wing and tail, so their lever arms around the center of gravity change.


How does a self-centering rudder affect left-turning tendency?

First, "adverse yaw" refers to the increased drag of a down aileron (and reduced drag on an up aileron) -- which mean that as you deflect the ailerons to roll left (in order to turn left), the adverse yaw makes the nose yaw right -- exactly the opposite of what you want. Therefore you balance any application of aileron with just the right amount of rudder to counteract the adverse yaw. This is called "coordination".

For any control surface (like rudder or aileron) there is a small "dead zone" around neutral, where movement of the surface does not have an appreciable aerodynamic effect. Those narrow strips reduce the size of that dead zone and improve control. Therefore they help, not hurt.

What you're talking about is what the FAA (and others) call "left-turning tendency". When flying straight and level, the engine power affects the amount of rudder required, and significantly so. At high power more right rudder is required, and especially so at low speeds like climbing. At low power settings less right rudder is required, especially at high speeds -- so in a descent many aircraft require left ruder to straight. (Of course this is most applicable to single-engine airplanes where the fin is in the propwash.)

To help the pilot with the forces required, surfaces have trim tabs -- see Why Pitch Trim Up/Down & Roll Left/Right switches on yoke or control stick?

(Incidentally, many older small English engines like the dh Gipsy engine, https://en.wikipedia.org/wiki/De_Havilland_Gipsy_Major, turn the opposite direction so airplanes like the Tiger Moth that use that engine have a right-turning tendency and require left rudder.)


How common are gear-driven or belt-driven superchargers in modern aircraft?

Lycoming offered mechanical superchargers in some of their large 6 and 8 cylinder opposed engines like the GSO-480 but such engines have been out of production a long time.

I would say the only mechanical superchargers to be found on any engines manufactured today would be found on Russian or similar Eastern European radial engines like the M14P.

I'd be pretty shocked to hear of a homebuilder incorporating a mechanical supercharger, but maybe somebody will find an example. In any case, if you're going to do it, so much easier to do it with a turbo.  The thing that makes turbocharging difficult to work seamlessly in cars, the power lag issue, isn't a problem with aircraft, so a turbo is a no-brainer that can be done by the homebuilder on just about any engine if they really want it.  To incorporate a mechanical drive system on an engine not designed for it would be quite a daunting task.


How strictly are language rules adhered to between Pilot and ATC?

Standard Phraseology is what should be used, but especially in those countries where the local language is an allowed IFR language, you will get deviation from that in daily use, either due to dialect, accent or simply colloquial terms influencing the phraseology used between pilots and ATC.

In countries like the USA, where English is the local language anyway, you will sometimes hear non-standard phraseology being used. In countries like Germany, where English is not the local language and IFR is only allowed in English, you will have pilots and ATC adhering to standard phraseology more closely, especially to avoid misunderstanding due to local accent.

Anecdotal comment: I fly in Germany and usually use English also for VFR. Germans have a very phonetically hard sounding pronunciation in English, making the language sound clipped and sharp, which carries over to phraseology being used. Many native English speakers have commented though that this makes it really easy to understand, because every word is spoken very distinguishedly. Although I speak English fluently without accent in normal day use, I tend to slip into a German accented English in aviation... because it's easier to understand.


What makes the Air Force and Navy pilots different?

Navel aviation pilots are specifically trained for anti ship and anti submarine warfare roles and they are also trained for carrier based operations. They are also trained for ground attack, dogfight etc. Air Force pilots does not have carrier based landing skills and they do not have anti submarine warfare capabilities.


What are the performance trade-offs in the Icon A5 spin resistant airframe?

Though performance details of the aircraft are not available, there seems to be a significant weight penalty associated with making the aircraft spin resistant.
It appears that the aircraft had to get a specific exemption for increased MTOW (1680 lb as against 1430 allowed) due to the incorporation of spin resistant design. Note that the weight given by the manufacturer is 1510 lb, still more than allowed.
As required in the exemption, the aircraft had to be fitted with a ballistic recovery complete-aircraft parachute system, affecting the payload. The engine power is also limited to 135 hp. The range is also low (~300nm).


Are some tail wheels made out of solid plastic?

You can see that sort of thing on ultralights that land at 25-30 mph where they may use a solid once-piece wheel made of some elastomeric plastic or rubber.  Smaller airplanes however, will use a rubber tire on an aluminum wheel with proper bearings, due to the very high rolling RPM once you are landing above 40 mph (or at least a bushing that can take high speeds and loads).
The smallest ones usually have solid rubber tires and once you get to a certain size, say on airplanes over 1500 lbs or so, they will be pneumatic tires.  For example, an Aeronca Champ usually has a solid rubber tailwheel, but it's heavier and faster Citabria descendant has a pneumatic tailwheel tire.  You can browse typical tailwheel tires here.


What makes intentional low or missed approaches legal?

Well, I'm going with "It's a written exception, but nobody thought to include it in 14 CFR 91.119 though".

I say this because there are a number of regulations that require a student pilot or applicant for a license to receive and log flight training for go-arounds.

For example:

14 CFR 61.87 - Solo requirements for student pilots
14 CFR 61.98 - Flight proficiency (Recreational Pilots)
14 CFR 61.107 - Flight proficiency (Private Pilots)
And others

The complete text of the private pilot SEL requirement (and they are all similar) is:

  §61.107   Flight proficiency.

  (a) General. A person who applies for a
  private pilot certificate must receive and log ground and flight
  training from an authorized instructor on the areas of operation of
  this section that apply to the aircraft category and class rating
  sought.

  (b) Areas of operation.

  (1) For an airplane category rating with a single-engine class rating:

  (i) Preflight preparation;

  (ii) Preflight procedures;

  (iii) Airport and seaplane base operations;

  (iv) Takeoffs, landings, and go-arounds;

  (v) Performance maneuvers;

  (vi) Ground reference maneuvers;

  (vii) Navigation;

  (viii) Slow flight and stalls;

  (ix) Basic instrument maneuvers;

  (x) Emergency operations;

  (xi) Night operations, except as provided in §61.110 of this part; and

  (xii) Postflight procedures.


Is training required under §61.55 to move from PIC to SIC?

No training needed.  If you are typed in the aircraft, none of the SIC type stuff applies (that is just an ICAO formality and is superseded by having a normal type rating).  As long as you meet the requirements to act as SIC (landing currency, company training currency, etc) you are good to transition to the right seat with no additional training.


The atmospheric pressure is dropping quite signigicantly with altitude - and this is the very point of the concept of the altimeter - messure the pressure and show this as an altitude.

The basic concept of a flight level is that all high flying planes share a common reference - and do not neet to consider local weather, which can change quite dramatically during a flight. The main topic here is traffic seperation - so all should use the same reference and thus can quite compare their altitudes.

But flying low there is a nice problem called "ground" - planes should mostly avoid it. On charts the minimum altitude is noted, as well as special places like airports. Here a more precise view on the altitude is needed - so pilots need to set their QNH. Before takeoff, before landing - or when flying low for a longer time quite frequently.

But where to change from one reference to another? That much depends on the location - in the US it is mostly 18000, but in other regions this can differ substantially.


In aircraft where the thrust reversers are not locked out when airborne, is it permissible to go around after reverser deployment?

An aircraft approaching to land with a reverser deployed or unlocked, particularly one that's deployed unintentionally, will be at idle power, or shut down on the deployed reverser.

A go-around or missed approach is conducted in the same manner as if the engine is shut down for any other reason.


Does a flight instructor rating supercede a ground instructor rating?

The flight instructor certificates held at that point provide all the same privileges.

This is not true.  A ground instructor certificate is valid to give ground training for all aircraft... airplane, helicopter, glider, balloon, etc.  A flight instructor must have those ratings on their certificate.

Record keeping requirements also differ between the two certificates.

§61.189(b)(2) requires the flight instructor to keep a record of all knowledge test endorsements to include the student name, date, kind of test and result.

The ground instructor has no such requirement.

The flight instructor must also have an advanced or instrument ground instructor certificate to qualify for a gold seal.


What advantages are there to operate a corporate flight department under Part 135 as a separate entity instead of in-house as a Part 91?

There is no reason you can't operate as a part 91 department but simply adopt the standards of 135.  Government contracts work this way.  It's all pt91 work but adheres to pt135 rules.
Actually holding a 135 is a lot of work and is expensive.  The training and checking requirements are onerous for your average flight department.  How do you feel about potential career limiting checkrides every six months?  You also need to keep the planes up to a higher standard.  This means observing TBO hours and calendar times.
You don't mention aircraft types, but Continental requires piston engine overhauls at 12 year intervals or upon reaching the time limit, whichever is first.  Even a piston single becomes expensive to operate.


FAA Knowledge Test Question Bank - What is the source of the actual test questions?

Years ago (35?), I taught ground school for pilots.  The question pool was not published then (it was later published, and then withdrawn), the company would send college students to take the FAA test, with the idea that they would capture certain questions, so that they could be edited and put into study guides.

As I recall the goal was about 5 questions per student taking a test.  Most of the students were not pilot candidates, but rather engineering and even humanities students at colleges.

Attendees would also report on small differences after they had taken the written, and the company question pool would be revised.

I cannot tell you what process is used today.


If airliners profit by moving luggage from checked to carry-on, why do some LCC gate-check luggage?

A number of LCCs don't carry cargo at all or have a more limited cargo business, especially in Europe and the US. This is particularly the case if they're flying smaller narrowbody aircraft on shorter routes, where freight has to be bulk loaded. Ryanair and easyJet aren't in the freight business, though Southwest and AirAsia are.

LCCs have strong motivations to reduce turnaround times and ensure maximum utilization of their aircraft. Freight can slow down operations (somebody has to get it to the gate on time, it has to be loaded/unloaded) and so can carry-on bags (everyone has to carry them, find a space for them, lift them, and once the bins are full, it takes time to collect the excess bags, tag them, and get them downstairs and into the hold). Getting passengers to gate-check bags early can help speed the boarding process. It's the gate agent's job to get the aircraft off on time, so they're motivated to gate-check bags before there's a problem fitting them in the overhead bins.

In addition, passengers find carry-on baggage convenient. You don't have to wait for it, don't have to worry about it getting lost, and you can access it during the flight. LCCs make extensive use of ancillary revenue, with a la carte airfares that involve extra charges for anything passengers might consider convenient, from a preferred seat to a beverage. As such, some airlines charge for carry-on bags (or disallow them on their cheapest fares), extracting more revenue from those who value this convenience and speeding the boarding process by reducing the number of carry-on bags.


Do pilots land a helicopter sideways for improved visibility of the landing area?

No.  Often helos use windows on the floor of the cockpit near the anti torque pedals, which allow a pilot to look directly down at the landing area, as this example of a EC130 shows.

Helicopter pilots seldom land at a sideways angle, save for landing on slopes terrain or a situation required to fit the helicopter into a space.


How far could the Wright brother's catapult have thrown their unpowered plane?

The catapult cannot launch an unpowered Flyer II at all.

Robert's comment reaches the right conclusion using potential to kinetic energy, though his frictionless answer up to takeoff overestimates available energy and depends on aero drag not to take flight. The corrections are:

All the potential energy from the weight is not transferred to the flyer. The weight builds kinetic energy that is dissipated as it slams into the ground. Its velocity is one third that of the flyer.
Though the tower is 20ft tall, the weight only falls 16ft(5m). The rope and weight take up space.

Setting potential energy of the weight equal to kinetic energy of weight and plane:

$$ M_w\cdot H_w\cdot g=\frac{1}{2}M_f\cdot V_f^2+\frac{1}{2}M_w\cdot V_w^2$$
$$635kg\cdot 5m\cdot 9.8\frac{m}{s^2}=\frac{1}{2}\cdot 408kg\cdot V_f^2+\frac{1}{2}\cdot 635kg\left(\frac{V_f}{3}\right)^2$$
$$130\frac{m^2}{s^2}=V_f^2$$
$$V_f=11.4\frac{m}{s}=25mph$$
Since the Flyer II needed 28-30mph to become airborne, the catapult cannot launch the unpowered flyer by itself, even excluding friction and drag.


You ask about Jeppesen in the title, but you mention ICAO in the body.

Does Jeppesen show top altitude? Yes.

Top image is FAA chart, bottom is Jeppesen. Both for the LOOP SID.

Does ICAO show top altitude? The ICAO charts are produced by NAAs based on ICAO's style if they don't have their own. The FAA has its own format. But the answer is also yes if the top altitude is used.

The top altitude was added for the climb-via instruction, which is a recent addition. Not all states (nations) follow the climb-via and descend-via system just yet. But those who do, will have that information.


Why is the Constellation's nose gear so long?

The Connie's fuselage has a subtle S shaped contour which was intended to conform somewhat to the upwash ahead of the wing and downwash aft of the wing, with a final upturn at the end to place the horizontal tail at the desired vertical location.

They also tapered the fuselage to the smallest cross sectional area possible at the nose, to part the air gently you might say, so the bottom ends up sloping up toward the nose.

Then you have main gear legs that are fairly long because the R3350's propellers are quite large.

The wing incidence is set to optimize the fuselage curvature's presentation into the airflow in cruise.

At the same time, you want to have wing chord in a certain desirable AOA range sitting on the ground, and you want to keep the tail from sitting too high (the Connie has the 3 surfaces to keep the vertical height of the tail low enough to fit the common hangars of the day).

Combine all those factors together and you end up having to the make the strut really long, and ending up with the most graceful airliner ever designed.


What does it take to turn a 747 around 180 degrees?

How long, and how wide of a turn depends entirely on three things:

What is the true airspeed.
What is the bank angle of the turn?
Is level flight maintained during the turn.

Since it's easiest to calculate, and presumably what you intended, we'll assume #3 is true (level flight). However, if you really needed to get turned around fast, turning in a descent will give you a tight turn without the extra g-forces.

Cruise Speed for a 747 depends on altitude, generation, company guidelines, etc, but we'll go with Mach 0.85 for this example, which seems to be in the ballpark. If we say it's cruising at 35,000 feet in standard atmospheric conditions, that comes out to 490 knots TAS.

Next, pick a bank angle. A reasonable bank angle for that airplane with passengers on board is 25°, and you could probably get away with 30°. Anything beyond that will cause passengers to complain. Of course, if it's an emergency you might consider something higher. Just remember, the higher the bank angle, the stronger the g-forces which will be felt by the people inside, and the aircraft itself, which has structural limitations. The G-force can be calculated using:

$$
gforce = \frac{1}{\cos(bank)}
$$

For an example, let's select 25° bank since that's the most realistic.

Radius

Calculate the radius of the turn using this formula, slightly modified from Wikipedia to give nmi instead of feet:

$$
Radius\ of\ turn\ in\ nautical\ miles= \frac{velocity^2}{68579 \times \tan(bank)}
$$

Which gives us:

$$
7.51nmi = \frac{490^2}{68579 \times \tan(25°)}
$$

So the turn itself would be about 15 nautical miles wide (≈ 91,000 feet) not accounting for wind.

Distance Traveled

Using basic geometry, the distance traveled for a 180° turn is $d = r\pi$ (half the circumference of a circle), so:

$$
23.59= 7.51\pi
$$

Giving us 23.59 nautical miles traveled.

Duration

$$
time\ in\ minutes = \frac{distance \times 60}{TAS}
$$

Therefore, at 490 knots (nautical miles per hour) and 25° bank, it would take about 2 minutes, 53 seconds to complete the turn.

$$
2.89 = \frac{23.59 \times 60}{490}
$$

You could go through and calculate the results for any speed and bank angle you want. This is true regardless of the type of airplane in question.

Turning in a Descent

Your edited question asks how much altitude would be lost if it were not a level turn. There is also no single answer to this question because it depends entirely on how you perform the maneuver.

One reason you may have to descend in a turn is because the increased lift results un increased induced drag, and the aircraft engines may not have enough power to compensate, resulting in the decreased airspeed, and possibly a stall. In this case, the equations for calculating the turn radius are exactly the same as in level flight. The amount of altitude lost will depend on the descent rate required in order maintain airspeed, which will vary depending on the engine power available, the weight of the aircraft, and the drag curve at the given speed and AoA. Peter Kämpf's answer gives an example of what this might look like for a 747 in a 1.5g turn.

Another version of a turning descent would be an accelerated descent. The advantage in this case it that it would allow turns to be made without additional g-force. The disadvantage is that you'll be accelerating downwards instead of descending at a constant rate. This can get out of hand very quickly and would only be good for very short duration turns.

To illustrate this disastrous option, let's look at what would happen in a 1g turn at the same 25° and 490 knots TAS. Since the math is more complicated, it'll be easier to talk about this portion in metric units. Here's a conversion table:

1 nautical mile = 1852 meters
1 knot = 0.514444 meters per second
1 foot = 0.3048 meters

First, in order to maintain a constant 1g, the lift vector is simply rotated in the turn (instead of rotated and increased in order to maintain altitude). Therefore, the magnitude of our lift vector will be equal to the acceleration due to gravity near the Earth's surface. We'll round that to 9.8 m/s/s.

Inward Acceleration

Our acceleration towards the center of the turn $a_c$ (the portion of our lift vector pointed inwards instead of up) can be determined using the following equation where $\theta$ is the bank angle:

$$
\sin(\theta) = \frac{a_c}{g}
$$

Solving for $a_c$:

$$
a_c = g\sin(\theta)
$$

Therefore

$$
4.142 = 9.8\sin(25°)
$$

Radius

So 4.142 meters per second per second is how fast, at 25° of bank, and 1g, we'll be accelerating towards the center of the turn. With that, information, along with our known velocity, we can calculate the radius of the turn using this equation where $v$ is our velocity in meters per second, and $R$ is the radius in meters:

$$
R = \frac{v^2}{a_c}
$$

Plug in our numbers:

$$
15341 = \frac{(490 \times 0.514444)^2}{4.142}
$$

This comes out to a radius of 15341 meters (8.28 nautical miles).

Distance Traveled

Now that we have our radius, we can calculate how long it will take us to turn 180°. This part is the same equation as before.

$$
48195 = 15341\pi
$$

Giving us 48195 meters (26 nautical miles).

Duration

Distance divided by velocity gives us duration.

$$
t = \frac{d}{v}
$$

In our case:

$$
191.2\ seconds = \frac{48195}{490 \times 0.514444}
$$

So, it'll take 3 minutes 11 seconds to complete the turn.

Downward Acceleration

The last value we need before we can calculate the altitude lost in the turn is to calculate how fast we're going to be accelerating towards the ground in this turn. Lets first calculate the upward portion of our lift vector:

$$
a_u = g\cos(\theta)
$$

Therefore

$$
8.882 = 9.8\cos(25°)
$$

Our lift vector is accelerating us upwards at 8.882 m/s/s, while gravity is trying to pull us down at -9.8 m/s/s. That comes out to a net vector of -0.918 m/s/s.

Altitude Lost

This part requires a little bit of calculus because our descent rate is accelerating. The integral of acceleration is velocity ($v = at$), and the integral of velocity is distance:

$$
d = \frac{at^2}{2}
$$

So, lets calculate the change in vertical distance (altitude):

$$
-16780 = \frac{-0.918 \times 191.2^2}{2}
$$

So, theoretically, our airplane lost 16,780 meters of altitude (55,052 feet). Of course, since we were only 35,000 feet in the air to begin with, this is rather bad news for us. Besides hitting the ground, you would also come close to risking structural damage to the airframe because in this example, 490 knots is considered the speed over the ground, but the total velocity would be higher (about 596 knots) by the end of the turn due to the sink rate.

You'll also notice that, assuming we had the altitude to lose in the first place, the turn took longer to complete than in level flight. This is because the magnitude of the lift vector was smaller.

You can feel free to experiment with other speeds and bank angles, and you could also experiment with higher g turns (simply replace $g$ in the equations with $2g$ or similar). In some cases higher than 1g, you may actually gain altitude, though it's unlikely a 747 would be able to sustain a high-g maneuver which gains altitude.

As a quick second example, consider a 2g turn with 80° of bank at 400 knots:

$$
a_c = 19.302 = 2g\sin(80°) \\
R = 2193.8 = \frac{400 \times 0.514444}{a_c} \\
d = 6892 = R\pi \\
t = 33.5 seconds \\
a_u = 3.404 = 2g\cos(80°)
$$

Giving a total altitude lost of 3589 meters (11,775 feet) over 33.5 seconds. However, at the end of the turn, you would have a sink rate of 214 meters (703 feet) per second. That's over 42,000 feet per minute. It would likely be possible to recover from that in the altitude remaining, but it would not be pleasant.


Many of the 'variables' you mention, are in fact fixed, and in large determined by dispatch (the smart folks at the company). For commercial flight, the flight plan will be filed in advance (generally by the company dispatch), and will contain all the waypoints en route, including expected flight levels. Dispatch makes the calculation for the most efficient flight in close collaboration with ATC authorities, for example by reserving slots on certain airways.

Deviations from the flight plan are not common - you won't hear ATC tell an airplane mid-flight to suddenly take the long way round - instead, any route alterations are communicated to the pilots when they are still on the ground, and if necessary, extra fuel is taken on board.

This flight plan is then given to the pilots, and programmed into the FMC. The FMC is a very sophisticated piece of software, and can in fact calculate the required fuel for this leg all by itself - you can even program it to calculate the best trade-off between efficiency and speed (see this KLM video at 1:40). I'm not entirely sure about the details, but you can probably program the SID and STAR of the departure and destination airports respectively as well.

On top of this, extra fuel is taken on board for things like taxi, expected holding patterns (your dispatcher will know how busy you can expect it to be at your destination airport; e.g., Heathrow is generally very busy and you might want to take some extra fuel on board), and enough fuel to at least be able to perform a few go-arounds or a diversion if circumstances call for it. In the end, the pilot is responsible for taking enough fuel on board, but will rely on the FMC and dispatch to make an educated guess.


Would a piston or turbine engine be best suited for a small UAV flying 8000miles?

Not to burst your bubble, but doing this "cheap" isn't possible.
First look at range. Light aircraft that have a 2-ton+ payload have limited range, look at the upcoming Cessna 408, it can carry 3 tons but only has a 1,000 mile ferry range. In order to increase the range, you need to carry more fuel, reducing your load. So lets say you dedicated 1 ton to a fuel tank (neglecting the weight of the tank/piping), that gives you an extra ~300 gallons, maybe an extra 500 miles (I don't have info on fuel burn rates at this time, just a generous guess).
Now, you want 8,000 miles, so you need something that can carry a lot of fuel. Now you're in the 767-ish sized territory, so payload won't be a problem, nor will range (when you add , but it will be expensive. A new 767 cost around \$100 million, or you can lease it for between \$600,000 and \$650,000 per month.
If you need an aircraft with air-drop capability, now you need to find something ex-military. A C-130 won't do (range is only about 2000 miles), even the gigantic C-5 Galaxy only has a 4,800 mile range. There just doesn't exist an aircraft to do this.
Add on top of that the cost of developing an autonomous flying system with take-off and landing capability, you are well into the $200 million range at this point.
So now what? You've got a 767 with large payload capability (but no air-drop) that can fly somewhere and back. Time to fly right? Nope! You now (and have been for some time) need to deal with regulatory requirements for multiple jurisdictions since you are crossing a lot of unrelated airspaces in your flight. You need to coordinate demonstration flights and paperwork, along with all the compliance needed for a "one-of-a-kind" aircraft. Many won't want you flying over populated areas, or may deny you completely. Might have to do some lobbying ($$$).
Ok... got it, regulations approved, flight approved, aircraft bought, cargo bought, time to fly? Almost, try getting insurance. It will be expensive, probably hundreds of thousands per month.
A flight crew is the least expensive thing here
If you are serious about this, save yourself \$100m to \$150m and hire a qualified crew. You don't have to go through the development of this automated system, the regulatory approvals, the test flights, the insurance costs, the reluctance to have a 90+ ton aircraft flying without any operator intervention at 500 miles per hour and just hire somebody to fly it.
Pilots aren't the most well-paid, but lets say you have 2 crews making \$100,000/year each ($400,000/year total) with benefits. That's \$33,333/month, for the cost of development (lets say \$100m) of the automation system, you can employ these people for 250 years.


How does a Fenestron remove or reduce the tip vortex losses in a helicopter?

There are basically two effects here:

One is the ducted fan effect. Ducted fans are more efficient than open fans, specifically creating smaller vortices at the blade tips.
The other is the fact that the tail rotor of a helicopter is not situated in an area with almost linear airflow along the rotor axis. It is also submitted to:

A steady flow due to helicopter forward motion. This is coming from the side of the rotor, so affects opposite rotor blades differently.
A buffeting flow from the h/c main rotor. This is an unsteady flow, also coming laterally from the point of view of the tail rotor (actually, the top).

Fenestron tail-rotor ducts can be considered a fairing that reduces airflow across the rotor. The end result is that the rotor blades are in a much smoother flow that helps reduce unwanted turbulence. This is one of the reasons such rotors are quieter than regular open tail-rotors (the other being the fairing material absorbing some of the noise).


In short, VNO doesn't provide you any protection, it just tells you that flying that fast puts you in a regime where structural damage will occur before increased load factor will cause a stall -- regardless of weight.

For part 23 airplanes that are not turbine powered and VD has not been established, 23.1505(b) establishes VNO must be established such that it is between VC,min and 0.89*VNE.  Section 23.335 defines VC as a multiplying factor of the square root of wing loading at design maximum takeoff weight.  For normal and utility category airplanes, VC is design cruising speed and is be between 33 √(W/S) and 0.9 VH where W/S is wing loading at the design maximum takeoff weight.  The factor 33 may be scaled as low as 28.6 based on W/S values greater than 20 (the regs do not provide units on any of these numbers...).   VH is the maximum forward airpseed in level flight at maximum continuous power at sea level.

Section 23.335 also defines VA and the only relation to VC is that VA need not exceed VC.

We can see from this information that establishing VNO is a design choice based ultimately upon maximum possible wing loading as a guideline and unlike VA stall speeds are not involved in the calculation.

What you can take from this is that VA will vary by weight (because this affects the stall speed) but VNO is based upon wing loading at max gross takeoff weight and is constant with actual weight.

Flying slower than VA you will stall before causing structural damage.  Flying faster than VA you will cause structural damage before stalling the airplane.  VNO will be at least the VA or higher.  Flying below this speed doesn't really tell us anything (VA is better for that), but flying above this speed lets us know the design margins for load factor induced structural damage are such that we don't want bumps or abrupt control deflections because we can damage the airplane.

Regulation excerpts.

  §23.1505   Airspeed limitations.

  (b) The maximum structural cruising speed VNO must be established so that it is—

  (1) Not less than the minimum value of VC allowed under §23.335; and

  (2) Not more than the lesser of—

  (i) VC established under §23.335; or

  (ii) 0.89 VNE established under paragraph (a) of this section.

  (c)(1) Paragraphs (a) and (b) of this section do not apply to turbine airplanes or to airplanes for which a design diving speed VD/MD is established under §23.335(b)(4). For those airplanes, a maximum operating limit speed (VMO/MMO airspeed or Mach number, whichever is critical at a particular altitude) must be established as a speed that may not be deliberately exceeded in any regime of flight (climb, cruise, or descent) unless a higher speed is authorized for flight test or pilot training operations.

  §23.335   Design airspeeds.
  Except as provided in paragraph (a)(4) of this section, the selected design airspeeds are equivalent airspeeds (EAS).

  (a) Design cruising speed, VC. For VC the following apply:

  (1) Where W/S′=wing loading at the design maximum takeoff weight, Vc (in knots) may not be less than—

  (i) 33 √(W/S) (for normal, utility, and commuter category airplanes);

  (ii) 36 √(W/S) (for acrobatic category airplanes).

  (2) For values of W/S more than 20, the multiplying factors may be decreased linearly with W/S to a value of 28.6 where W/S=100.

  (3) VC need not be more than 0.9 VH at sea level.

  (c) Design maneuvering speed VA. For VA, the following applies:

  (1) VA may not be less than VS√n where—

  (i) VS is a computed stalling speed with flaps retracted at the design weight, normally based on the maximum airplane normal force coefficients, CNA; and

  (ii) n is the limit maneuvering load factor used in design

  (2) The value of VA need not exceed the value of VC used in design.


What did the "gear warning horn" on the North American P-51 sound like?

Interesting question.  Unfortunately, I couldn't locate the part in the P-51D/K parts catalog, but, if an E-bay seller is to be believed, it had an E-2 Faraday horn, which appears to be an electrically actuated alarm.  Faraday is (was) the name of an alarm manufacturer most commonly known for their fire alarms.  Based on a history paraphrased from cteksys.net (emphasis is mine), this seems to be plausible:

Faraday, was founded in 1875 and is now one of the leading
manufacturers of Notification Appliances, Fire Alarm Control Panels,
and Clock Systems in the United States.  (Statement in 2002) ...
... In the 1940s Documents have been located with the name Schwarze-Faraday at 130 Church Street Adrian Michigan showing the
company pressing into signaling equipment for industrial applications
including factories , ships, and airplanes.

It's not the original, but a circa-1960s Sperti-Faraday horn (the company name from 1937-1965) sounds like this:


What market share does Jet A-1 have in the commercial airline market?

Chevron writes

Jet A is used in the United States while most of the rest of the world uses Jet A-1. The important difference between the two fuels is that Jet A-1 has a lower maximum freezing point than Jet A (Jet A: –40°C, Jet A-1: –47°C). The lower freezing point makes Jet A-1 more suitable for long international flights, especially on polar routes during the winter.
However, the lower freezing point comes at a price. Other variables being constant, a refinery can produce a few percent more Jet A than Jet A-1 because the higher freezing point allows the incorporation of more higher boiling
components, which in turn, permits the use of a broader distillation cut. The choice of Jet A for use in the United States is driven by concerns about fuel price and availability. Many years of experience have shown that Jet A is suitable for use in the United States.

Notably, the US is also the single largest market for aviation fuel worldwide, so it has the volume to support a separate type. There's consumption numbers in the same document.
The disadvantage with Jet A is with long-haul flights that experience cold air, the 7 degrees can make a difference, forcing the flight to descend to warmer levels to heat the fuel, increasing consumption.
One thing that can be done is a sample of the loaded fuel is taken and the actual freeze point determined, and that number used in flight. Usually for Jet-A this lies somewhere in between the two specs.


Well there is at least one case where this is true and it's used by the military - A Case 3 instrument approach to an aircraft carrier.

The approach is essentially equivalent to a terrestrial military TACAN approach coupled with a precision microwave landing system on final approach.  See the basic plate below.  Both IMC and night VFR conditions require a Case 3 approach per NATOPS.

As to civilian seaplane bases, the answer is actually, yes, some do.  One example is the GPS RNAV approach into Greenville Seaport (52B) in Greenville, Maine.

As for an instrument approach to land a seaplane at a arbitrary point in the middle of the ocean, no, I am not aware of anything like that.  Maybe one day an advanced version of GPS or some similar satellite based navigation system coupled with an advanced INS could allow a pilot to arbitrarily pick a point then create a custom approach which provided lateral and vertical guidance to the landing site.  Even if you could do this, you still face unknown hazards like surface winds and waves (seaplanes were never made to brave rough open ocean swells).  It would be virtually impossible to safely land on a moonless night.


What is the optimum viewing angle to search for something on the ground from the air?

Straight Down is most likely the best angle but there is of course cases to be made for other scenarios. In your case if you are looking for something on the ground that is potentially obstructed a straight down view is going to give you the most direct view and will prevent something from falling out of frame if an angled view cause an obstruction to block it.

The real problem in areal viewing/photography/imaging is the air its self. They touch upon it in this podcast nicely but when it comes to spy satellites (a similar use case) the actual resolvable resolution was limited by the air not the imaging sensor. Its important to go up on a clear day as haze, even VFR legal haze can have a big impact on this.

If you are intending on using a GoPro I might advise getting something with a longer lens (especially if you intend to be at any kind of substantial altitude). For comparison you can check out some of the stuff I have captured with a GoPro here none of that footage was shot over 5000 and most of it below 3000 and it is difficult to pick out smaller objects on the ground in the footage. At the flat mounting angle I use you can see how trees obscure things behind them.

As for mounting bigger lenses, its clearly impractical to point large lenses straight down but there is a work around. Historically spy planes used some kind of mirror set up to look straight down at the ground mounting the large lenses flat in the plane pointed at a mirror.

There are even some smaller GA planes built for this specific purpose with cameras already mounted. Some may simply have a camera trap door. It may be worth it to try and track down this kind of service for your mission.

Your lens choice will also be quite important. The GoPro has a fairly wide lens which offers a great big field of view but considerable edge distortion in actual practice at longer distances. I would advise trying to rent or borrow (unless you own) a decent DSLR with a standard to short-tele lens. On top of that I would not video tape the adventure, I would set the camera to take a series of time laps photos pointed straight down. Most modern cameras can resolve a much higher res image photo than they can video and in the end of the day at a modern frame rate you are going to end up with a log of overkill footage at your given speed. This is how planes like the SR-71 did it back in the day. In this case a decent GPS enabled camera is key, remember you are looking through this data after the fact so you need to know where the picture was actually taken to make it useful.

You also need to think about field of view a bit. The wider the lens the more land you can cover in a single pass at a given altitude but you do so at the cost of angular resolution. The longer the lens the smaller field of view with the benefit of higher angular resolution.

Note: You will find some info out on the web about the use of wide angle lenses in areal imaging. The common ones were the likes of the Zeiss Biogon and Distagon mated to either a custom platform or in the case of the moon missions a Hasselblad body these particular lenses are phenomenally sharp in the edges even wide open. They are however the exception to the rule and most modern wide lenses make trade offs to be compact and light weight. To be safe I would stay away from wide lenses (anything bigger than maybe 28mm on your standard Full Frame SLR) for your trip.

One fairly reasonable option is the variety of mirror reflexive telescope/tele-photo lenses out there. Something like this one could be useful in your endeavor. A few of these have passed through my collection and they are far from great but they do get the job done when you need a big lens in a small package. However I would take a used lens like this one which can be had for the same price any day.

For the sake of a complete answer Im going to add more details although in your specific case they may not apply.

The most successful areal imaging programs quickly adopted stereo imaging setups. In this case 2 cameras were used each mounted slightly off axis of centerline. The Corona program as well as the KH-7 Gambit satellites used such a system with great success. The images when viewed later created a somewhat 3D rendering of the ground which provided superior analysis abilities over the more traditional single camera units. This kind of effect could be achieved with 2 cameras mounted on some kind of bar and a little pre calibration.


Does the stator blade angle changes? Why?

The picture above shows the velocity triangles for one axial compressor stage. You can see that a big factor for the angle at which the airflow leaves the rotor, is strongly dependent on U the rotational speed of the rotor. So when the engine runs at different powersettings the air is gone come at the stators at different angels(since U is changing). Since the stators are like wings and have an optimal angle of attack, it makes sense to make them rotate so they can always keep this optimum angle, even if the oncoming flow changes its angle.
So it doesn't really have much to do with whether the plane is on the ground or not, the major factor for the stator adjustment is the changing rotational speed of the compressor rotors.


What was enabling control to the pilot on the Snecma C-450 Coléoptère?

Great find, a vehicle with so many new design features in a time before Computed Fluid Dynamics, and hard to test in a wind tunnel where the device could only be mounted in a fixed position.

From this source:

  Takeoff, hover, and landing were controlled by deflecting vanes in the engine exhaust: in horizontal flight by four fins mounted just above the castoring landing gear, and in the transition to vertical flight by two retractable canards in the nose.

This source states that the four delta surfaces were movable and were to be used to control horizontal flight. They were puny though, and mounted quite close to the aircraft roll axis. One of the problems encountered during test flight was a slow uncontrolled roll.

  For the control of the aircraft in fast flight, there were four cast solid control surfaces allowing in-depth aerodynamic control (horizontal control surfaces) or in rolling and direction (vertical control surfaces). For the phases of vertical takeoff and landing, control was ensured by deviation of the jet (pitching and lace) and of compressed air coming from the compressor (rolling).

The same source has a frontal view of the craft:

So yes the four delta surfaces were able to pivot but were obviously inadequate for providing any control at low speeds. Thrust vectoring was required for slow flight.


What safety issues led the FAA to ban Constellation flights into/out of the U.S.?

Individual airlines, or even all of the airlines from entire countries, are sometimes banned for safety reasons. It was the Dominican airlines, not the aircraft, that were banned by the FAA.

It is just coincidence that many of these un-safe airlines flew Lockheed Constellations. They were banned from flying ANY aircraft into the USA.

The Wikipedia article talks about the end of Constellations used in commercial airline service, but it was the grounding of the airlines that caused the end, not the grounding of any particular aircraft.

Here is a link to a NY Times article describing a ban of all airlines from nine different countries.

Sept 3rd 1994 NY Times article

  The Federal Aviation Administration has barred airlines from nine nations from flying to the United States because of poor safety procedures.

  The unusual action, announced today, is a response to safety questions
  from consumer groups. Officials say they hope the economic fallout of
  the ban will encourage the airlines to follow safety guidelines.

  The aviation agency surveyed safety procedures in 30 of the 93
  countries that have commercial flights to the United States. The
  agency sought to determine if the aviation authorities in each country
  were meeting the safety requirements of the International Civil
  Aviation Organization, a United Nations agency. Its rules are less
  strict than those of the Federal Aviation Administration.

  The aviation agency did not reveal details about the safety
  deficiencies that had prompted it to ban the nine airlines.

  The banned airlines are from Belize, the Dominican Republic, Gambia,
  Ghana, Honduras, Nicaragua, Paraguay, Uruguay and Zaire. Four other
  countries were allowed to continue flying into the United States, but
  under increased supervison by the aviation agency. They are Bolivia,
  El Salvador, Guatemala and the Netherlands Antilles.


What is the exact meaning of "manoeuvring" when said by ATC in reference to traffic?

To add to @HiddenWindshield's answer, it's explained in UK's CAA Radiotelephony Manual CAP 413:

Traffic Information and Avoiding Action Phraseology
5.21 Relative movement should be described by using one of the following terms as applicable:
(...)
5. 'manoeuvring' where the conflicting traffic’s flight path and/or level information is unpredictable and/or showing significant variation.


Is it a rules violation for a pilot to intentionally frighten a passenger to the point of hysterics?

There's no regulation that I can see that says "don't frighten your passengers". And there probably shouldn't be: almost anything could frighten a nervous person who isn't familiar with aircraft, even if the maneuver (or whatever) is completely normal.

Having said that, if the FAA thinks you've done something stupid then they do have a 'catch-all' regulation that they could argue you violated.

14 CFR 91.13

  No person may operate an aircraft in a careless or reckless manner so
  as to endanger the life or property of another

I haven't watched the video but I think it's at least plausible that the FAA could say that there was a real risk that the panicked passenger would take the controls and try to fly the aircraft themselves. In a dive, pulling up suddenly could easily stall the aircraft and stall recovery is not intuitive or obvious to a non-pilot. In the worst case, pulling up suddenly from a dive can actually tear the wings off. So it would be very easy for the passenger to damage or destroy the aircraft and potentially fly into people or property on the ground.

Finally, apart from the aviation regulations, it might be possible for the passenger to sue the pilot for causing stress and emotional damage. You could always ask on law.SE about that.


What's the point of having ILS on runway signs?

These markings designate the hold-short point during different runway operations.

Runway hold-short points are marked by white text on a red background. They designate a point which any aircraft must not cross without an explicit clearance from ATC. Note that in the below picture, there are two markings:

Cat II or III ILS is used during low visibility operations. In the case of an auto-land, the autopilot literally lands the plane on the runway. To do this, the aircraft systems need a very precise signal from the ILS antenna. Any aircraft on the ground crossing the line of sight between the ILS antenna and the landing aircraft will interfere the signal, sending the landing plane off course.

When a plane is landing on Cat II or III, other planes on the ground need to stay further back the runway. This has an undesirable side effect - the airport capacity is reduced. If somebody is doing a visual approach on a clear day, you can move a bit closer.

This is what happened to a Singapore Airlines Boeing 777 when it used auto-land without informing ATC. Since no one is aware they're using auto-land, the standard hold-short procedure (rather than the low visibility procedure) applies. They drifted off the runway pretty much like a racecar!


Why would a canard wing be more prone to icing than a stabilizer?

It has to do with the local speed around the airfoil.

In a canard configuration, the forward wing has to produce more lift per area than the main wing in order to have natural longitudinal (or pitch) stability. This means the suction is more intense, and the pressure on the upper side of the airfoil right behind the leading edge is lower than on the main wing. Also, the angle of attack of the wing is higher, presenting a larger area to the oncoming flow. Large droplets of supercooled water will simply splash on the leading edge and freeze there instantly, causing clear icing.

In a conventional aircraft the tail surface will provide very little lift, and in many cases even produces a small downforce. Now the main wing shows lower pressure on the forward part of the airfoil, just where ice collects the most. In the special case where the tailplane is in the wake of the wing, some of the water droplets will have frozen to the wing already and less water will be available to cause tailplane icing.

The capacity of air to hold water depends not only on temperature, but also on pressure: The lower the pressure, the more likely it is for condensation to happen. Condensed, super-cooled water, or liquid water hitting a cool surface, will form ice. Now you have both components needed for the explanation.

Pitch stability is the explanation for the higher propensity of canard wings to collect ice than conventional tailplanes!


What does flight categories "C", "G", "T" etc. mean?

I got the answer.  'C' is commercial, 'G' general aviation, 'T' taxi, etc.

Update:

http://www.faa.gov/air_traffic/publications/atpubs/fss/AppendixA.htm, under section "Type of flight", it lists

  S  if scheduled air service

  N  if nonscheduled air transport operation

  G  if general aviation

  M  if military

  X  if other than any of the defined categories above.

But types C and T isn't there.


How are operators of small UAS craft supposed to know about flight restrictions?

Information about current and future TFR areas is available from the FAA, even as an easy-to-read map. If someone is planning on flying a manned or unmanned aircraft, that should be on their list of things to check ahead of time.

As far as other airspace restrictions, we have a question detailing the different types of airspace. It would be worthwhile for a UAS operator to learn enough about reading charts to at least know the airspace in the area where they intend to fly.

Another option would be to attend ground school or at least do some amount of self-study. Just as pilots need to know how to operate according to the rules of the airspace system, UAS operators could benefit from the education.


Why are there so many different propeller shapes?

The best design depends on what your goal is. This changes with operating conditions:

Best power/thrust ratio

For lightly loaded propellers this would be minimum induced loss. These are the propellers on human-powered aircraft, windmills or motor gliders. Minimum induced loss is achieved by distributing circulation elliptically across the propeller disc, and a typical consequence is a small chord near the tips and a low number of propeller blades. If you want to research this more, I recommend to play around with XRotor by Mark Drela (and maybe reading this). Mark used it to design the MLE (below, NASA photo EC87-0014-8) and Dedalus propeller.

Maximum thrust at high speed

Highly loaded propellers, which can be found on large turboprop aircraft, are less concerned with induced loss, but need to put out as much thrust as possible with a limited prop area. The diameter is restricted to limit tip speeds, and the tips typically are mildly supersonic. To limit the suction peaks on the blades, the local lift coefficient needs to be low, which is achieved by increasing chord and the number of blades. Increasingly, now tip sweep is also used, but this drives up the torsional loads on the blades and leads to warpage in operation. An extreme example is the P-27 prop on the D-27 turboshaft of the An-70 transport (below, picture by Marina Lystseva).

Ship propellers

They operate in a medium which is 800 times denser than air, and the main concern is to avoid cavitation. This again means to limit suction peaks and leads to very high blade chords. To limit draft, ship propellers need to have extremely small diameters.

Submarine propellers

For submarines, add  minimum noise emission to the design goals. Minimum draft is not a concern, so the propeller blades are less stubby. Their sweep distributes the cutting through the wake of the rudders over time, which helps a lot to reduce noise.

The fancy shapes of some model aircraft propellers have more to do with marketing or unscientific voodoo beliefs by some hobbyists. Generally, a straight shape works best.


Why are podded engines preferred over engines fitted inside the fuselage or wing?

Most important factor affecting drag is frontal area. Almost all frontal area of the engine pod is the intake and it has to have the size it does to collect the air the engine needs. So there is not so much drag to be saved.

Beside that, embedding the engine in wing roots like De Havilland Comet did has many disadvantages, most of which also apply to the central engine of three-engined jets (B727, DC-10):

The wing root carries the weight of the aircraft, so weakening it by embedding the engine is design and construction complication.
Access for maintenance is difficult. Engines need a lot of maintenance and sometimes need to be replaced.
Uncontained failure is more dangerous (see UA232).
There is not much structure to damp vibration, so it is awfully noisy.
And last but not least, modern high-bypass turbofans are huge. They would not fit in the wing anyway.

And reasons for not attaching the engines directly to the fuselage or wing are already mentined in Why do we use pylons to mount the engines on jetliners?. Mainly, the inlet needs:

Free space around it from which it can draw air at slow speed.
Free space around it to which it can spill the excess air at high speed.

And the engines mounted forward of wing actually improve the distribution of cross-sectional area according to the Whitcomb area rule and they dampen flutter, so the wing can be slightly less stiff and thus slightly lighter.


What is a (rough) rule of thumb for calculating fuel consumption in a modern jet airliner like Boeing 737 - 300?

Here are some very rough values for the 737-300, that a certain airline uses to compute manual flight plans in case the computer system fails.
Climb - 2950lbs / 15mins
Cruise - 5500lbs/hr
Descent - 600lbs / 20mins
Hold - 2650 / 30mins
Alternate - 1950 / 20mins
Min arrival fuel - 6300lbs
Recomended arrival fuel - 8300lbs
These numbers were based on a 27000lbs payload (approx 130pax plus bags)

source: http://www.airliners.net/forum/viewtopic.php?t=722273

[EDIT: I've edited the answer to remove any mention of the 737-300 being one of the most common 737 variants, thanks for the constructive comments!]


What is the amount of lift produced by friction?

First, let me illustrate how I understand your question. Please comment accordingly if I got you wrong.

Below you see the friction drag computed by XFOIL for an airfoil at 3° angle of attack.

Friction drag over chord for an E502mod airfoil at 3° AoA. Blue: Top surface, Red: Bottom surface. Source: XFOIL 6.97.

And here is a plot of the pressure distribution at that point:

Where the longest arrow pointing at the airfoil contour points to is the stagnation point. So the large blue peak in the first plot is exactly in the region of the nose where its curvature is strongest and the surface is mostly vertical. Integrating all the friction drag over the height of the airfoil should result in a small upwards component from that high local friction around the nose. Lift, from friction, in other words.

Did I understand that correctly?

I've never seen that component of lift being mentioned separately, and even XFOIL does not include it in its calculations (just checked the FORTRAN source I have lying around). You assume correctly that this component is indeed negligibly small, it is about two orders of magnitude smaller than the pressure forces.


How do seaplanes do run-up checks without brakes?

I'll limit my answer to single-engine seaplanes as I've never flown a multi-engine seaplane.

Typically there is no need to stay stationary in the water when doing a run-up. Just do it while taxiing to your takeoff path, or you can do it on your takeoff path. If the takeoff path isn't long enough to do the run-up and then continue along the path for the takeoff, you can turn around, taxi back along the takeoff path, and then takeoff.

At typical run-up power settings, if you hold full up elevator, the airplane will simply mush along on the water since you won't have anywhere near enough power to get it up on the step. In other words, you won't be going very fast.

When giving floatplane instruction, one of the first things I tried to impress on students was to not think in terms of the constraints of straight, hard-surface, defined runways, taxiways and the like. There's no need, typically, to taxi in a straight line, make well-defined taxiing turns, and no need to takeoff in a straight line. Once away from the dock or beach, the airplane is going to weather vane unless you actively oppose that, and that weathervaning is going to have a component caused by the current, if any, of the water you're on.

In my experience, most of the time the takeoff path was either dictated directionally (a river) or pretty much wide open (lake or reservoir). For new students in my area, reservoirs were preferred. More often than not, it was a matter of getting a short ways off the dock, do the checks other than the run-up while moving away from the shore at a 90 degree angle more or less, lift the water rudder, bring the stick all the way back, and do the run-up, all the while letting the aircraft weathervane into the wind. Then just takeoff.

I never flew a twin-engined seaplane, but I see no reason why you couldn't bring both engines up to the run-up rpm, do the checks on one and then the other. While checking the mags, carb heat, and props, there would be a little asymmetrical thrust, but not enough that the rudder couldn't handle that.


Have any operational aircraft ever used over wing fuel tanks?

Early aircraft designs used gravity feed to supply the engines with fuel. All those designs had their tanks located above the wing, and in biplanes in the center of the upper wing. The picture below (source) shows an Etrich Taube with the cylindric fuel tank mounted above the fuselage.

The next application of overwing tanks were "Doppelreiter" fuel tanks (slipper fuel tanks) which were used on some German fighter airplanes in WW II. They were mounted above and behind the wing, and to everyone's surprise they had little impact on the top speed of the airplanes, and in case of the Me-309 helped to increase it slightly. They were the first practical application of Küchemann carrots and worked much like the flap track fairings of today's airliners.

FW-190 A with Doppelreiter tanks.


Why is autolanding ILS a thing, but not autotakeoffing ITS?

Autoland exists at least in part because a pilot can't safely hit (the right part of) the runway (at the right speed and attitude) without visual references, so a lot of precision electronic guidance equipment is needed, and then even more equipment to ensure the first equipment is working correctly.

In contrast, the sky is much bigger than the runway. It's comparatively easy for the pilot to hit the sky even without visual references (provided vis is good enough to taxi out). So none of that fancy stuff is necessary.


Where exactly are the pitot tubes positioned on the A330/340?

Seems like they are under the cockpit for the A330

source

Couldn't really find anything for the A340 that helped with answering your question but I assume based on the A330 that they most likely are located somewhere in the same area.


Why do some AFBs have planes parked at 45 degrees to others?

McGuire AFB being an Air Mobility Command (AMC) base, accounts for the very large C-5 Galaxy when it visits. It may not seem like it, but the 68 m (220 ft) wide C-5 when parked at a 45-degree angle saves ~20 m (65 ft) -- approx. one-third of its wingspan.
The reference used by the USAF is AFMAN 32-1084 (PDF), from which:

2.1.5.4.1. Parking Dimensions. Table 2.9 presents the minimum geometric criteria for fixed-wing apron design. When designing new aprons for AMC bases hosting C- 5, C-17, KC-10, and KC-135 aircraft, provide 15.3 m (50 ft) of wingtip separation.
EXCEPTION: When you are rehabilitating an existing apron, provide the maximum wingtip separation the existing apron size allows (up to 15.3 m [50 ft] but not less than 7.7 m [25 ft]). This additional separation is both desirable and permitted.

By applying that to the C-5 and adding the clearance to the taxiway, those angled spots are a perfect fit:

The measurement above (~83 m) shows two half-span C-5s (68 m) plus the clearance (15.3 m), with superimposed C-5s via pinterest.com

For the other examples you've stated in a comment: Beale AFB and Albuquerque Airport, Tinker AFB, and March AFB -- in that order:

The parking spots are between two taxiways, so it's the same reason as the main example. It also makes parking and taxiing out easier.

Those by the hangar are for ease of taxiing out instead of a hard left and potential for collision.

Plenty of space. I couldn't find a 45-degree parking.

(All imagery is via Google Earth)


Do I use true or magnetic north in headwind component calculations?

Surface winds, as reported by the tower are magnetic.  Runway headings are magnetic.  However, METARs are reported true, according to Aviation Weather Services and ICAO.  Therefore one has to perform a heading correction in comparing runway headings to METARs.

Wind directions are normally rounded to 10 degrees, as are runway headings.  However, sometimes runway numbering lags isogonic shifts, so care should be used utilizing runway headings.

It is worth noting that the expression, "If it is written it is true, and if it is spoken it is magnetic," may be misleading.  As an example ASOS and AWOS data is recorded as true, and transmitted as true, but is converted to magnetic prior to being broadcast on computer generated voice messages.

Furthermore TWEB are true, as the underlying reports they are generated from are true (winds aloft, TAF, etc.).

To summarize, runways are magnetic, tower wind checks are magnetic, but ASOS, AWOS and METAR are true, unless transcribed to computer generated voice.


Do helicopters need to use yaw pedals to fly a coordinated turn?

Many helicopters have different flight characteristics, but for general information you can always look in the FAA Helicopter Flying Handbook, this is from Chapter 9:

This is from a section on the four fundamentals of flight (straight-and-level, turns, climbs, and descents):

  Anticipate the following characteristics during
  aggressive maneuvering flight, and adjust or lead with
  collective as necessary to maintain trim and torque:

  Left turns, torque increases (more antitorque).
  This applies to most helicopters, but not all.
  Right turns, torque decreases (less antitorque).
  This applies to most helicopters, but not all.

So some (most) helicopters do require some torque pedal movement for aggressive maneuvering, but the pilot may have anticipated this and added the correction prior to beginning the turn. You may not have noticed as much pedal movement as you would in a coordinated turn for an airplane, or the helicopter you were riding in had different flight characteristics and was not maneuvering aggressively enough to need it.

Many helicopters "wind vane" pretty well, that is that they stay aligned with the relative wind at high speed. It could be that the helicopter you were in was travelling at a high enough rate of speed that a large (or any) correction was not needed to maintain proper alignment.

For an example of how speed cancels out the need for anti-torque control, see this article about a helicopter pilot that lost the tail rotor and continued to fly for half an hour to a proper landing site.


How to find out what engine a plane had in the past?

Airlines are not free to use any engine that they can shoehorn into an airframe. Engine choices are constrained by national regulatory authorities that grant approvals to use specific engine variants in given airframes.

A Google search will usually identify which engine models are used in a specific airplane model. For an authoritative answer though you would have to consult official records e.g. civil aviation records for a specific aircraft or the national regulatory authority or airline with respect to a specific aircraft model.

So for certainty you should consult the German civil aviation authority, the Luftfahrt Bundesamt or Lufthansa. For practical purposes though a cursory Google search combined with good judgement suggests that your 1999 Lufthansa flight would have certainly employed a pair of CFM56 engines.


What control surfaces do I need to move to do a roll in a model aircraft?

The ailerons should be connected so that they move opposite each other. When one aileron moves up, the other one must move down, and vice versa. In fact, in full-size aircraft, the ailerons are connected so that it's actually impossible to move them in the same direction*. So, to answer your question, to roll to the right, the right aileron must move up and the left must move down.
*Well, certain airplanes have "drooping ailerons": when the flaps are deployed, it causes both ailerons to tilt downward slightly. But this is about increasing lift at low airspeeds, it doesn't affect how the ailerons control.


Why do the flap maneuvering speed margins to stick shaker depend on altitude?

It's because the air is thinner, meaning the dynamic pressures are reduced for a given velocity through space, but the inertial mass of the air frame is the same as at sea level. Or you could flip it over and say the inertial effects (true airspeed) are higher for the same indicated airspeed (dynamic pressure). In other words, the dynamic forces have less influence over the inertial forces for a given velocity and mass. As well, the thrust margins to accelerate out of a stall are also less.

Best illustration is to take it to an extreme.  Say you are at 45000 ft, flying near stall at 150kt indicated.  That is, the dynamic pressures of the air are equivalent to 150kt at sea level. However, your actual velocity through space is roughly 300kt, so all of the inertial forces are effectively doubled relative to the aerodynamic forces, and on top of the that, you have more or less zero thrust reserve. You now have WAY less stick shaker margin, and a stall at that altitude requires extreme responses (aggressive dives to gain speed).

In your case, the effects are a lot more subtle, but still significant, especially approaching 20000 ft.


Is there possibility to Survive without brain damage at 30/35,000 feet?

Long term, no, it is not.  Any exposure to pressure altitudes over 26,000 ft will eventually cause death from hypoxia, even with acclimation to the higher altitudes.  There is a period referred to as Time Of Useful Consciousness (ToC) associated with hypoxia.  This is the approximate time that a healthy adult human with good lung capacity can maintain cognitive function.  These values can be halved if an explosive decompression occurs, which is why there is a requirement that airliners have quick donning, pressure breathing oxygen masks available to the flight crew and can be donned and establish the flow of oxygen within 5 seconds.  It is also the reason that flight attendants tell passengers to first don their emergency O2 masks, then assist someone else next to them in the event the masks are deployed.

Once ToC lapses at a given pressure altitude, cognitive function rapidly begins to fade away.  The person becomes listless, sleepy, but often euphoric.  Loss of consciousness, coma and then finally death will ensue unless the minimum partial pressure of O2 in the lungs is re-established.

Section 3-1 of the FAA Manual of Aviation Physiology is a good reference on the subject of hypoxia.

At the altitudes that Concorde cruised at, the air pressure is so low that decompression sickness becomes more of a risk than hypoxia.  Having the water boil away in your own bloodstream is a very painful way to die, and loss of consciousness via hypoxia would almost be a relief from that torment.