What to do to maintain my Spanish ULM (GA) gyroplane licence valid in the USA when moving there?

As a caveat here, I know nothing about gyroplanes. But based on the US regulations it looks like there are a few different possibilities.

If your ULM license is equivalent to an ICAO private license then you could get an FAA foreign-based private license as described in this question. I believe you would get category rotorcraft and class gyroplane (see 14 CFR 61.5) but I'm not completely sure.

If your ULM license is not equivalent to an ICAO private license then it depends on the type of gyroplane you want to fly. If it's considered an ultralight then you don't need any license at all. If it's an LSA then you would need a sport or recreational pilot license. If it's a 'regular' gyroplane, you would need a private license.

If you do need to get an FAA license (sport, recreational or private) you should be able to use time you logged in Spain to count towards it.


What are the advantages of a Spinning Wing (Magnus Effect) and why haven't any been commercially produced?

Some earlier prototypes of spinning-wing aircraft were produced but none were successful. The design has some very serious disadvantages. One of the main issues appears to be undesirable gyroscopic effects.

Production

  ... why it was never produced?

Several full-scale prototype aircraft with rotating Magnus-effect wings seem to have been produced:

921-V - Plymouth. 1930.
X772N - Union Aircraft Co. 1931.

It may be that 921-V is the only one to have flown, crashing after one flight.

   The Flettner airplane

  Built in 1930 (USA), the 921-V is reported to have been flown at least once - ending it's short career with a crash landing. Three cylinders with disks performing as winglets driven by a separate engine. Information on this design needed! It's probably the only aircraft equipped with cylinder wings which made it into the air.

From Pilotfriend.com

In practice the effect can be less efficient than conventional alternatives

  In the early 1920's the force from a rotating cylinder was used to power a sailing ship. The idea, proposed by Anton Flettner of Germany, was to replace the mast and cloth sails with a large cylinder rotated by an engine below deck. The idea worked, but the propulsion force generated was less than the motor would have generated if it had been connected to a standard marine propeller!

From NASA

Advantages

  What were the advantages?

The article referenced suggests

  More wing lift and less drag are the major aims of aviation’s researchers. Maybe the Magnus Wing will supply the answers ... The ship is powered by a conventional gas-turbine jet engine, while the drums are revolved by a separate piston engine. Small wings, heavy loads and quick take-offs would be its great advantages.

Disadvantages

The developer of a working model wrote about a few of the disadvantages (try a google translation of that page for more):

If the cylinder rotation accidentally becomes slow or stops, its lift disappears completely. This plane will never be able to glide.
If a gust blows from backside during a slow flight (takeoff or landing), the cylinder wings generate a down force.
The spinning cylinder wings generate a strong gyro effect, which makes it difficult for the plane to change its attitude.

See video and comments.

NASA did some experiments with rotating-cylinders for flaps (not main lift source)

They concluded

  These experiments demonstrated on the one hand the
  effectiveness of such a high lift system but on the other hand the weakness in handling qualities due to the gyroscopic forces in such an aircraft configuration.

From A review of the Magnus effect in aeronautics

The US Army also carried out a study of the use of the Magnus effect in aircraft
VIEW AND PRELIMINARY EVALUATION OF LIFTING HORIZONTAL-AXIS ROTATING-WING AERONAUTICAL SYSTEMS

It is difficult to pick out a simple conclusion as the study looked at a wide variety of systems. For rotating cylinders in wing (RCIW) they wrote

  Such systems do not appear to have merit as STOL devices.


What is meant by "fuel flow: on " in checklists?

In the real aircraft that checklist item would mean bringing the thrust lever of the engine to be started up out of cutoff and to the idle position. This would be accomplished by physically moving the thrust lever forward slightly out of the cutoff detent.

However, in the computer flight sim for which the linked checklist provides guidance, the cutoff position of the thrust levers is not simulated. Instead, thrust lever positions below idle command reverse thrust. For this reason, the checklist calls for using the computer keystroke ctrl-shift-F4 to command fuel flow on. This keystroke combination commands mixture full rich in simulated piston aircraft.

In the real Lear 45, fuel flow and scheduling during start is controlled by the Digital Electronic Engine Control (DEEC). For this reason, the start checklist calls for setting the appropriate thrust lever to idle prior to commanding engine spool up in preparation for the DEEC to automatically start actual fuel flow once the appropriate compressor speed is achieved.

It is worth noting that after initially setting the thrust lever to idle—or hitting ctrl-shift-F4 on your computer—the fuel flow indication should read zero. The check for appropriate positive fuel flow comes later in the start sequence.

Compared to setting the thrust lever to idle in the Lear 45, the analogous control command for starting most piston engines would be mixture to full rich and for most turboprop aircraft would be fuel condition lever to low idle or similar.


Which speed shall be used on high speed taxiway?

According to the ICAO manual on Aerodrome Standards (based on Annex 14) (link) - maximum 35 knots for code 1 and 2 runways, and maximum 50 knots for code 3 and 4 runways.

Since you are moving on the ground, it makes sense to use your ground speed as reference.

I imagine most aircraft operators have procedures for using rapid exit taxiways in their standard operating manuals. As a result, the actual speed used by air crews is likely to vary depending on which company they fly for.

IFALPA recommends that you slow down to normal taxi speed on the runway, and then use rapid exit taxiways with normal taxi speed (as opposed to the very low speed you would need to use to turn off the runway using a pendicular taxiway). (link)

From the ICAO manual:

  3.8.15

  A rapid exit taxiway shall be designed with a radius of turn-off curve of at least:

  550 m where the code number is 3 or 4; and
  275 m where the code number is 1 or 2;

  to enable exit speeds under wet conditions of:

  93 km/h where the code number is 3 or 4; and
  65 km/h where the code number is 1 or 2.

Note: you can find the definitions of the code numbers (1, 2, 3, 4) on page 17 of the manual to which I linked above.


Why does the Eurofighter Typhoon has a long arm canard vs the close coupled canard of Dassault's Rafale or JAS-39 Gripen?

The Viggen was the first canard aircraft ever to be built in production quantities. Its close-coupled canard is fixed, with landing flaps being the only movable part. Its purpose is solely to maintain aerodynamic flow over the wing at high angles of attack and thus enhance both manoeuvrability and low-speed handling. Saab were not able to develop movable canard technology in time, nor was it necessary in order to meet the aircraft specification. Nevertheless, getting the darn thing into production after 60 years of failure was a staggering achievement.
The Gripen, Rafale and Typhoon canards are also used to maintain high-alpha airflow. However theirs have an additional function as control canards. Their own angle of incidence can be varied to help control aircraft pitch directly, to contribute to other more subtle manoeuvres, and (at least in the case of the Typhoon) to minimise radar cross-section.
The further forward a control canard is placed, the smaller it need be to provide sufficient control authority, just as a long rear fuselage allows a smaller tailplane. Its only real issue is that it interferes more with pilot visibility, but its smaller relative size minimises that.


Do all B777 family aircraft have the same engines?

TL;DR: No.

For the true answer refer to the FAA Type Certificate Data Sheet

777-200

2 Pratt and Whitney Turbofan Model:
PW4074, PW4074D, PW4077, PW4077D,PW4090,PW4084D, and PW4090-3
(Engine Type Certificate No. E46NE)

2 General Electric Turbofan Model: GE90-76B, GE90-85B, GE90-90B, GE90-94B
(Engine Type Certificate No. E00049EN)

2 Rolls-Royce Turbofan Model: RB211-Trent 875-17, RB211-Trent, 877-17,
RB211-Trent 884-17, RB211-Trent 892-17, or RB211 Trent 892B-17, RB211 Trent 895-17
(Engine Type Certificate E00050EN)

777-300

2 Rolls-Royce Turbofan Model: RB211-Trent 884-17, RB211-Trent 884B-17,
or RB211-Trent 892-17
(Engine Type Certificate E00050EN)

2 Pratt & Whitney Turbofan Model: PW4090, PW4098
(Engine Type Certificate E46N)

777-300ER

2 General Electric Turbofan Model: GE90-115B
(Engine Type Certificate No. E00049EN)

777-200LR

2 General Electric Turbofan Model: GE90-110B1

2 General Electric Turbofan Model: GE90-115B

(Engine Type Certificate No. E00049EN)

777F

2 General Electric Turbofan Model: GE90-110B1

2 General Electric Turbofan Model: GE90-115B
(Engine Type Certificate No. E00049EN)


Was the 1992 Gimli DHC-4 Caribou accident ever investigated?

It was, but from what I can tell the report has not been digitized yet.

The gust locks were left installed. The aircraft was being operated in the restricted category as they were retrofitting with the PT-6’s.

Here’s an analysis from James Donnelly, Bombardier Aerospace. Starts on page 7.

http://www.asasi.org/papers/2001/Four%20Unrelated%20Accidents.pdf

Essentially the rigging was done incorrectly. The gust locks did reduce engine thrust, but didn’t kill it completely. Takeoff roll was 20% longer than calculated.


Why are visual approaches (in the US) preferred by US pilots, but not European pilots?

Capacity
If a visual approach is offered, and it gets accepted by the pilot, the airport can declare higher capacity. Whereas IFR procedures reduce the airport's capacity.
US and European airports handle their slots differently. Europe plans for the worst, which can on good days limit the full potential. The US plans for the best, which can on bad days end up in huge delays.[1] I've also explained it here. In short, if in the US they started offering more IFR procedures during good weather (VMC), they won't be able to back up the declared capacity.
Generally, airports are closer to the cities in Europe than in the US (apart from coastal cities) due to the different city planning (old vs. new). Airports in close proximity to cities have approach procedures that are designed for noise abatement, and are best flown as precisely as published.
Familiarity
So in general, the pilots are used to different systems. Also pilots that don't fly a lot in the US—like foreign carriers—are not as familiar with the surroundings as local pilots are. A Flight Safety Foundation briefing[2] discusses the risks associated with visual approaches for airplanes heavier than 12,500 lb:

Accepting an air traffic control (ATC) clearance for a visual approach or requesting a visual approach should be balanced carefully against the following:

(...)
Crew experience with airport and airport environment.

It's about knowing what to look for, especially when a particular visual approach does not have a visual approach chart.

An example of a visual approach chart showing landmarks; airnav.com

Use of ILS in emergnecy
Regarding the specific video about the bomb threat and the pilot's request to have the ILS turned on, for that scenario in particular it's because an ILS approach is less demanding,[3] especially in such high workload environment. (Also the flight was diverting mid-route.)

Poor professional judgment/airmanship (...) Decision to execute a nonprecision approach, instead of an ILS approach, in demanding conditions to
expedite arrival (...)[3]

1: Odoni, A., and T. Morisset. "Performance comparisons between US and European airports." Proceedings of the 12th world conference on transport research (WCTR), July 11–15. 2010. (paper; presentation)
2: Flight Safety Foundation ALAR Toolkit. ALAR Briefing Note 7.4 — Visual Approach. (PDF)
3: Khatwa, Ratan, and Robert L. Helmreich. "Analysis of critical factors during approach and landing in accidents and normal flight." Flight Safety Digest 17.11-12 (1999): 1-2. https://www.jstor.org/stable/44729511


Why is the Tu-144 the only commercial airplane with canard configuration?

Short answer: Canards make most sense with negative static stability and high maneuverability. Commercial aircraft don't need either, so a conventional layout works best.

For a statically stable aircraft, the conventional layout gives most efficiency with sufficient damping. Static stability requires that the forward lifting surfaces create more lift proportionally to their size than the rear surfaces. Here is an answer to a related question.

You want the airplane to return to the original flight attitude if it has been disturbed, say by a gust or a jolt on the stick. This can be done by creating proportionally more lift with the forward surfaces (= the wing in a conventional configuration) than with the rear surfaces (= the wing in a canard configuration). Say the jolt pitches the aircraft up. Now the aerodynamic forces should change in a way which increases lift proportionally more on the rear surfaces, so the aircraft pitches down and returns to it's original attitude. By distributing lift the way I mentioned above, the same change in angle of attack on both forward and rear surface will create a proportionally higher lift increase on the rear surface, making the aircraft (statically) stable.

That requires that one of the (mostly) two surfaces is not contributing as much to lift creation than it could. You want this surface to be the smaller one of both, so the whole configuration can create as much lift as possible at a given speed. A canard would be a poor choice for a commercial airplane, because the big wing would now fly at a fraction of it's potential.

Once you shift the center of gravity back to improve maneuverability, things get different: Now the rear surface is creating proportionally more lift, so the smaller surface should go in front. Voilá, a canard!

Now add forward sweep, which will make the wing tips twist to higher angles of attack when lift is increased, and you get a really responsive aircraft (but need to be careful not to overstress it!). This was done on the X-29 and the Berkut.

As jwenting pointed out, the canard on the Tu-144 was not a control surface, but should be considered a detached slat of sorts. Also, by adding some lift ahead of the wing it allows to lower the wing flaps in slow flight, increasing the lift potential of the main wing while maintaining the location of the center of gravity and stability.

And while we are at it: The Piaggio Avanti has a canard, and a conventional tail, too. Here the canard helps to put the wing spar behind the cabin area, makes it easier to fly with a wide range of c.g. locations and to increase aerodynamic damping. This is one of very few examples in commercial aircraft of canards done right!


Why does an engine bleed system failure restrict operating elevation?

Without more details on the specific aircraft you are talking about, it isn't possible to give a very specific answer.

In general, if a commercial aircraft is unable to pressurize the cabin fully (usually to <8,000 ft, thanks @jwzumwalt, for both safety and comfort reasons), the operating ceiling is reduced to compensate. The human body doesn't play nicely with high altitudes, so to make sure that passengers and crew don't asphyxiate, the cabin must be pressurized to a safe level.

If one of the engine bleed air systems is inoperative, which among many other things provides for cabin pressurization, the remaining compressed air capacity is diverted to more mission-critical systems on the aircraft. This leaves the cabin pressurization system starved of the compressed air it needs, resulting in it not being able to fully pressurize the cabin to a safe and comfortable level.


Can you jump out of a crashing plane just before impact to improve your chance of surviving?

Why can't they jump from it when the plane almost reaches the ground?
  They would have higher chances of surviving, right?

Wrong.

Remember your body still has roughly the same momentum it did when it was in the vehicle - just because you jumped out doesn't mean you're not still moving forward at a rate of speed the human body simply isn't designed for.

Let's reframe your question:

  If you were in a car doing 60 miles per hour and you knew the car was about to crash into a brick wall, would you jump from the vehicle, or would you remain strapped into your seat where the car, seat, seatbelt, and airbag will all help absorb the impact?

As with a car, being inside an aircraft and properly restrained will afford you substantial protection from the initial impact, and some of the crash energy will be absorbed damaging the aircraft. That increases the length of time it takes to decelerate your body and gives you a better chance of survival.

If you jumped out of your friend's Cessna because it's going down and might hit some trees your unrestrained body would be decelerated far more abruptly when you hit the trees (or the ground).
You might survive, but you've lessened your chances considerably (and the Cessna is a best-case scenario - your forward speed would be around 60mph as in the car example. For something like a 747 you'd be in the 150 mile-per-hour range or faster when you jumped out, which is almost certainly not survivable).


Why are the guns on the AC-130 not mounted on the underside of the aircraft?

By putting the guns on the side, the gunner can direct a continuous stream of bullets at the intended target for as long as the pilot wishes to continue circling it. If the guns were belly-mounted, the pilot would have to make multiple passes at the target zone from different directions, with long pauses between them- long enough for the enemy soldiers to reposition themselves and escape.


What are the pros/cons of ram air turbines?

You have kind of answered your own question. The down side to ram air turbines is they cause drag.

The up side is that they provide power outside the internal generating capacity of the aircraft (e.g., in emergencies when there is no power).

In the case a of a jamming pod, having its own power source eliminates/reduces the need to rely on internal power. That makes the pod modular. If the pod did not generate its own power, there would need to be a generator inside that sits there regardless of whether the pod were attached.


Any FAA or other regulations prohibiting taxiing between parked aircraft?

There isn't any such regulation.  That part of the airport is a "non movement area" (if you want a reference).  Of course, you want to be a good neighbor, and not toss rocks, etc.  I usually push my airplane into parking, and pull it out before engine start.  But that is just me.


How would modern jet fighters engage and defeat prop driven fighters?

Merge

Assuming neither aircraft tried for a head-on guns snapshot, the goal of the jet against the prop will be to go out of plane with the prop post merge and deny the prop a quick guns solution.  By far the easiest way for the jet to go out of plane is to extend and then take the fight vertically.  This means that the jet is in full AB coming into the merge and well above cornering speed, while the prop is coming into the merge at its best corning speed hoping to get a quick snapshot.  As the aircraft approach both pilots tighten down and pass as close as possible to prevent either aircraft from taking angles right after the merge (ie, so that neither aircraft has a turning advantage immediately post merge).

Post Merge

As the aircraft make their first pass, the prop (knowing full well the jet will take the fight vertically) begins a max performance turn hoping to quickly take angles and give itself a quick snapshot against the jet as the jet climbs.  However, the jet, knowing the prop is looking for a radius fight, extends the merge horizontally, at Mach 1+ and then begins a supersonic climb upwards.  Due to the lower thrust to weight ratio of the prop, most of the props potential energy comes in the form of its altitude; however, the jet has liquid potential energy in the form of fuel, and many can accelerate in the vertical, this gives the jet a decided advantage against the prop.  Because the prop cannot climb with the jet, and the jet is now outside of its guns range, the prop must remain at altitude and wait for the jet to attack.

Out of Plane

The jet, moving vertically, has now successfully moved out of plane with the prop rendering the turning radius of the prop moot.  An unchallenged out of plane maneuver is certain victory for the jet.  The jet can now cut the turning circle of the defender from above.  The best hope for the prop is to either pull hard into the jet trying to force an overshoot (and hope that the jet isn't already anticipating this and drawing a wall of lead between this anticipated spot and his current location) or, to wait until the last minute and pull into the vertical with the jet (causing a vertical merge) and hope for a head-on snapshot.  Either way, the jet can quickly disengage vertically again, causing the prop to bleed precious energy with these high G maneuvers, and then reengage when he has the advantage again.  Each time the jet disengages, the prop is left scrambling to regain its depleted energy, and the jet is maneuvering to prevent the prop from ever being able to fully recover.  This means that as the prop dives to gain speed, the jet dives after it, forcing another high G pull from the prop for another overshoot, or, if the prop tries to extend horizontally, the jet attacks again, forcing the prop to use more energy.

Conclusion

The jet will either force a mistake out of the prop and kill it, or the prop will eventually run out of altitude and airspeed and either auger into the ground, or be killed when he doesn't have the energy to force the overshoot, or climb vertically again.  This, of course, ignores things like thrust vectoring, and the flight computers, in aircraft like the super hornet, which give certain Gen 4/5 aircraft supermaneuverability--meaning, post merge, most Gen 4/5 aircraft could just out rate the prop and the fight would likely be over in seconds.


If DME is required, why have non-DME minima?

Conceivably the I-ETI DME transponder could be out of service, preventing you from identifying YOCUB (unless you have a second VOR or GPS), but you could still identify BASSO on the CHS DME for the missed.


(Note: This answer is tailored to the U.S. / FAA, because that is what I'm familiar with. All the citations and references are FAA materials. If anyone has any tips on possible international differences, please let me know and I'll edit them in. That said, I believe the descriptions I give are fairly consistent across the world, even if the FAA reg citations don't directly apply.)

  In what situations does ATC ask for ident, and is it ever required by procedure?

Generally, "ident" is used to help a controller identify an aircraft's secondary radar (transponder) return. By asking the pilot to "squawk ident," the controller can ensure that the aircraft he/she is talking to matches the radar target he thinks is that aircraft.

It can also be used for communication, to allow a pilot to respond if their radio transmitter has failed.

Specifically:

It is a method to allow a controller to identify an aircraft on radar, per section 5-3-3 of FAA Order 7110.65 (pdf):

  When using only Mode 3/A radar beacon to identify a target, use one of the following methods:

  a. Request the aircraft to activate the "IDENT" feature of the transponder and then observe the identification display.

For lost communication, per section 10-4-4 of 7110.65:

  Take the following actions, as appropriate, if two-way radio communications are lost with an aircraft:

  c. Attempt to re-establish communication by having the aircraft use its transponder or make turns to acknowledge clearances and answer questions. Request any of the following in using the transponder:

  1. Request the aircraft to reply Mode 3/A “IDENT.”

This last scenario is common when experiencing radio failures. If ATC suspects that you might be able to hear them but not to talk back, they might say something like "Cessna 12345, if you can hear me, squawk ident." If you reply by pressing the IDENT button, they can then issue you further instructions and ask you to acknowledge those instructions by pressing IDENT again.

  What does the transponder actually do in this mode?

In normal operation, every time the transponder receives an interrogation from a ground station, it replies with a data block containing certain pieces of information. This data block contains:

The encoded pressure altitude (for Mode C transponders)
A 12-bit identification code (this is the 4-digit code you select in the cockpit)
A single extra bit for the "ident" flag

When you push the IDENT button in the cockpit, the transponder sets that extra "ident" bit in its reply data. Anytime the transponder is interrogated while IDENT is active (for a set duration of time after you press the button in the cockpit), its reply data block will have the IDENT bit set. ATC computer systems notice this and cause the IDENT to be shown on the controller's radar display.

  What does the controller see on their screen?

It depends on the type of radar system in use. Generally the radar target will either blink, its symbol will change (or "blossom"), or an indication such as "ID" will blink in the aircraft's data block (where the callsign is shown).

The AIM has some schematic pictures that show what an IDENT looks like on an ARTS-III scope (an older system still in use at some TRACONs). See Figures 4-5-2 and 4-5-3.

I will try to find some pictures of other radar systems such as those used at ARTCCs and newer TRACONs.

  Does it depend at all on either the code or the mode the transponder is currently set for?

The code doesn't matter. The IDENT flag is an extra bit in the transponder's reply data that's independent of the 12 bits used for the code.

Obviously the IDENT will only be observed if the transponder is operating (not OFF or in a STANDBY mode). But the IDENT works in any mode used by normal civilian transponders (Modes A, C or S).


What is the speed limit in European airspace?

Airspace regulations do not fall under the authority of EASA. Each country has their own set of rules published under supervision of their own National Aviation Authority in the AIP.

The origin of the 250 knots IAS limitation below 10000ft can be found in the ICAO airspace classes definitions. The ICAO airspace definitions include a 250 knots IAS limitation below 10000ft / FL100 in:

Class C: VFR
Class D, E, F and G: both VFR and IFR

That means that in class A and B there is no speed limitation below 10000ft / FL100. In class C, IFR has no speed limitation, but VFR has. In Europe you will find a lot of class A, B and C airspace below 10000ft. In the US, there is no class A airspace below 18000' feet. There is class B and C airspace below 10000ft, but the FAA basically put a blanket speed limitation of 250knots below 10000ft, even inside class B and C airspace.

Also note that ICAO airspace classes are recommendations, countries have the authority to deviate from the ICAO recommendations as long as they publish these deviations.

Section ENR (En-route) 1.4 of the AIP contains the ATS Airspace Classifications and states includes the deviations from the ICAO airspace definition.


How is lift transferred from rotor to chassis (or weight, the other way around)?

The load path is rotor blade to hub, to mast, to mast bearing set inside transmission, to transmission housing, to transmission mounts/struts, to airframe.


How can I tell if a rental aircraft has been maintained in good condition?

From a fatigue perspective, this isn't really that much of a concern.  The beauty of metal structures is if they get "overloaded" one time, but the overload was not past the permanent deformation point, the yield point, of the affected structure so that nothing is permanently bent, the structure is fine, in general.  A hard landing that did hidden damage to the gear box should get detected at the next annual.
If you do a careful walk around and include gentle pokes and prods with your inspection, looking for loose bits or sloppy clearances, and everything is reasonably tight and straight, the chances of the thing letting go on you for no reason, while you are minding your own business sightseeing, are microscopic.  Look for stories of 172s just falling out of the sky because the wings let go without warning, and you will be looking for a long time.
Cessna once tracked down, back in the 70s, the most beat up high time 172 they could find, and located a 12000 hour airframe that had been used for pipeline patrol, to see how it was holding up.  It just required replacement of hinge bearings IIRC.  Corrosion is the bigger concern than overloads, and I might be wary of a 172 that has spent its entire life tied down outside (it's the daily condensation cycles that's the killer for outside parking unless it's in the desert) unless I was confident that the maintenance at the operation was good.  A 172 that is hangered every night will pretty much go forever.
Same with engines. Lycs and Conts are built like air cooled tractor engines.  Slow turning with large clearances and thick, heavy cranks and connecting rods, dual ignition, simple carburetors.  They usually give off warning signs if they are going to blow up on you (for example, an impending main bearing failure typically results in major amounts of oil coming out the breather line and coating the belly as the excess oil spews out the bearing and fills the crankcase with spray). When Lycomings go bad it's usually their weak point, the camshaft lobes, going south, and this puts metal shavings in the oil filter long before engine operation is affected, which should get caught at annual (as the cam lobe wears down eventually the engine will lose power and misfire).
If it starts nicely, runs nicely making normal static RPM at full power, oil pressure comes up smartly, isn't dumping oil everywhere, no crazy vibrations or scary sounds, the chances of the thing blowing up on you are maybe not microscopic, but pretty small.  Be observant of the FBO's maintenance operation; organization, cleanliness etc.
Learn some of the warning signs of engine trouble (like "morning sickness"; rough running that goes away as the engine warms up, a sure sign of a sticking exhaust valve, and which is guaranteed to get worse).
Statistically speaking, if you are flying around in a halfway decently maintained, straight and tight 172, at 3000 ft on a nice day, with gas and oil in the thing, you really have to work at it to kill yourself.


Are there other practical means of 'slowing' down an aircraft, other than parachutes?

For an aircraft to fly, it needs forward speed. If you slow down an aircraft too much, it will stall and fall out of the sky. Airplanes are designed to not slow down. It's not "if a Boeing 737 is slowed down to 80 knots, more people will survive". A Boeing 737 has to fly at 130 knots minimum. If you want a machine that can, it's a helicopter.

Most crashes happen suddenly, e.g. approaching a runway while not paying attention to airspeed. It's not like "Hmmm, I think it's going to crash in 3 minutes, let's arm this system to minimize injury". It's like, "we're stable, runway ahead, everything's good......(terrain! terrain! PULL UP!)......oh sh!t ! Max power!!!". If the pilot can foresee the accident, most of the time he can avoid it altogether.

If you know well in advance you ARE going to crash, chances are the aircraft is completely out of control, spinning around and falling. In this case I think a large enough parachute will be effective.


What safety differences exist between carrying laptops in checked versus carry-on baggage?

It's not about genuine laptops being safer as checked baggage. They're not, they're safer as carry-on baggage, where eventual fires can be identified, isolated and dealt with. That's why we have rules to make passengers carry-on lithium batteries more instead of checking them in. example

The reasoning explaining the ban is that an attacker might use the shell of a laptop to carry something on board. Turning on the laptop doesn't really prove much about it being genuine. You can take a Raspberry Pi that's size of a matchstick box, pair it with 2 AA batteries to create fake internals and  connect them to the original display. That'll make a gutted-out laptop appear to run for few minutes, enough to fool any quick inspection. Leaving rest of space and mass budget to hide something sizeable, like a bomb or a weapon.

That's why you can't circumvent the ban by removing the battery and taking a charger instead. It refers to "large electronic devices", not necessary ones with a battery.


What is the purpose of air that passes through the engine core in a turbofan engine? Is it mainly to spin the fan rotor?

The core is the Internal Combustion Engine - it has intake (of air), compression (of air), combustion (of the fuel/air mix), and exhaust (water vapor, CO2, air) that provides the motive force to rotate the turbine (N2) and provide perhaps 25% of the actual thrust of the whole engine when it exhausts out of the tailpipe.
From How Do Jet Engines Work? on this same forum, we get this diagram to aid us:

This core may also provide the motive force for electrical generators, hydraulic pumps, bleed air, ant-ice etc. (it would be inefficient and make no sense to get these from the fan air).
The thus driven turbine via it's shaft rotates the compressor blades at the front/intake of the core thereby completing a loop and making this cycle self sustaining as long as there's fuel to feed the engine.
The turbine rotation and the compressor rotation and the flow of air so induced also make the fan (bypass) part of the engine rotate (N1) through aerodynamic coupling. Thus the fan cannot function without the core, but the core can function without the fan.
So, yes, the objective is to drive the fan rotor, because the fan rotor by itself is not an engine and cannot self-rotate with purpose of producing thrust, but it is a device that can be driven by an engine  to produce thrust, around 75% of the total thrust of a typical combination.


Is there an ideal lift distribution for human-powered aircraft?

The essential feature of a human-powered aircraft is to maximise aerodynamic efficiency, which is to say to minimise drag for a given amount of lift. This is what the bell curve achieves. The elliptical distribution minimises drag for a given span, which says nothing about the lift available. The bell curve also gives you a lighter structure for a given amount of lift. Yes you can brace an elliptical wing for reduced weight, but you can brace a bell wing for an even greater reduction.
Also, the ideal distribution will depend on things like how tightly you want to turn. The inner wing will tend to stall, the outer wing to drag backwards (adverse yaw). Jonathan Bowers at NASA has shown that achieving the bell distribution through significant washout can create negative tip drag and proverse yaw. UK pioneer JW Dunne published as much in 1913. Washout also greatly reduces the problems of tip stalling and Dunne's biplanes proved wholly unstallable.
No doubt computer simulations could help refine the exact optimisation of washout, airfoil variation and span loading for the flight regime envisaged, as they did for Bowers' PRANDTL-D research drones, but it is not going to be far from the classic bell distribution.


Do any airplane designs exist that don't involve a flight surface that provides downforce?

There are multiple configurations which are possible with tail or canard, which based on their locations and whether they produce lift or down-force, results in a stable or unstable aircraft (taking the aircraft center of gravity into account). The figures below show some of the possible configurations.

Source: f-16.net

In the most general case, there is no need for even a canard or a horizontal tail as long as a (down or up) force is produced in some way. A good example is the Boeing Bird of Prey, where the chines produced (vortex) lift and thus a stabilizing force. The forces acting on the longitudinal axis of the aircraft look something like this, leading to a statically stable aircraft without any lifting surface except the wing.

Profile from bj-o23.deviantart.com, others own work.


What will happen on Airbus A320-200 series when during push back NW STRG DISC in not in the towing position?

The name says it all. NW STRG DISC or in full form the Nose wheel steering disconnect. And that is what exactly it does. It physically disconnects the nose wheel steering of the aircraft. In most aircraft, with nose wheel steering disabled, the wheel is allowed to caster. This allows pilots to maneuver the aircraft with the differential braking in case the nose wheel steering fails during taxi. So, yes even an aircraft the size of an A320 can be steered like a small aircraft with a castering nose wheel. So, a tow truck can turn the nose wheel of an A320 just like that.
The problem is that during push back the aircraft engines are started. With the engines started the aircraft hydraulics are powered and pressure is sent for nose wheel steering. The nose wheel, without any inputs always centers it self. During the push back if the nose centers it self, it can damage both the tow truck and the nose wheel of the aircraft. To prevent this the nose wheel steering has to be disconnected for push back. In the A320, there is a lever on the nose wheel which can be put in the towing position. Once it is placed in position, a bypass pin is inserted to ensure that the lever is held in place. Once the lever is positioned an ECAM memo NW STRG DISC is displayed in the cockpit in green. The message turns to amber colour when one of the aircraft engines are started. The whole point of the ECAM message is to increase pilot awareness so that you do not mistakenly leave the lever in tow position before commencing the taxi.

An Airbus A320 with nose wheel bypass pin inserted.


What are the prerequisites to join a flight School ? Is it different for each country?

What makes you think you can manage the exams for flight school if you can't even pass a high school exam?

They're at at least the same level of complexity...

But no, in general you don't need a minimum education level to start flight training. That said, if you want to get hired as a commercial pilot at some point, many employers WILL have education requirements without which they won't give you a job.

This is for EASA requirements, which are in use in the UK where you seem to be located. And of course individual flight schools may well decide to not take on people they expect to not have the capability to pass the exams, as having a high rate of failure on exams may reflect poorly on them. But that's not a legal requirement and would be a policy of the specific company in question.


Why would aircraft engines be mounted with "toe out"?

According to this source

  The engines were toed out slightly to improve engine-out handling;
  three tailfins were used to ensure that the aircraft could keep flying
  more or less straight if both engines on one wing went down.

I belive it was done to keep the thrust more equal in the event of an outboard engine loss, i.e. they are inline with the direction of flight when an engine loss occurs. Keep in mind that at the time these planes were designed engine failure was a [very]common thing and the mentality was a bit different than it is now. If a little bit of toe out mounting took a speed toll but made the aircraft far more controlable in the event of an engine loss it was considered worth while.

In modern multi-engine propellor aircraft counter rotating propellors (left side and right side props spin oposite directions) are generally employed to fix this problem and avoid the critical engine issue. I do belive that some single engine aircraft still do employ a slightly canted engine position for this reason.


Where does fuel from the boost pumps go before engine start?

I can’t say for sure about the jet engine mentioned. If I think of it like a piston engine, the fuel pump pressurizes the fuel lines. That in no way means that the fuel is entering the combustion part of the engine (cylinders in my case). It just means that the fuel lines leading to the fuel distribution point (carburetor or EFI) are being fed fuel at a certain pressure. A primer is a different story. It is feeding fuel directly into the combustion chamber by using pressure.

As mentioned in another post, more pressure and fuel is supplied by the fuel pump than is needed by the engine. In the case of a Cessna 172SP, the excess is routed to a reserve fuel reservoir. Here is a schematic of the fuel system from the POH.


Generally, War Emergency Power was a power setting that was available, but exceeded the engine's long term running condition rating.  It was usually specified in manifold pressure, and primarily applied to supercharged or turbocharged engines (which was most of the high performance piston engines by the end of the War).

The way it works was much like how it works in modern jets (where it often specifies afterburner operation): There was a stop on the throttle and a warning mark on the manifold pressure gauge that warned the pilot not to exceed those settings, as well as a specification in the manual for the longest permitted time in War Emergency Power setting.  To engage this setting, the pilot either had to manipulate the throttle lever in an unusual direction (pull up, push sideways) or break an actual wire with a push strong enough not to be done by accident, in order to bypass the stop.  In aircraft where it was used, the wire served to notify ground crews that WEP had been used.

Once engaged, War Emergency Power would give anything from 10% to 20% more total horsepower (in most cases, though the last version of the P-51 got roundly 60% increase), and a significantly increased rate of engine parts wear and risk of failure (blown gaskets, thrown connecting rods, even holed pistons from detonation if the fuel wasn't quite up to spec).  This doesn't seem like much, but 20% additional power would amount to 10 knots or more of additional level flight airspeed, or several hundred feet per minute of increase in climb rate -- it could make all the difference in air combat, when fighters of one force were often quite closely matched to those of the other in terms of performance.


The fuselage length is immaterial. The problem of the Max series relates to the positions of the engines versus the wing, and their aerodynamic interference near the at high alpha. The amount of fuselage ahead of the wing or behind the wing is not a major factor here.


Is the Mach number shown by an Air Data Computer considered a "true" Mach number?

For subsonic aircraft the Mach number is normally measured from dynamic pressure and static pressure, very similar to the way calibrated airspeed is measured.

$$M_a=\sqrt{\frac{2}{\gamma-1}\left[\left(\frac{q_c}{p}+1\right)^\frac{\gamma-1}{\gamma}-1\right]} $$

with:

$M_a$, the Mach number
$q_c$, the dynamic pressure
$p$, the static pressure
$\gamma$,  the ratio of specific heats (1.4)

If there is an error in the measurement of either the dynamic or the static pressure both the indicated airspeed and Mach number will be affected.

Note that the Mach number has no direct dependency on temperature.

The true airspeed is calculated by the ADC from the Mach number and the outside air temperature.

$$V_{TAS} = M_a \cdot \sqrt{\gamma R T_S}$$

with

$R$, the specific gas constant (287.05 for dry air)
$T_S$, the static air temperature

The indicated true airspeed has a direct dependency on the static air temperature ($T_S$,SAT) also known as the outside air temperature (OAT). The static temperature cannot be measured directly since the air will heat up on impact with the temperature sensor due to adiabatic compression. Instead the total air temperature ($T_\mathrm{total}$, TAT) will be measured.

The relation between the measured total air temperature and the static temperature is given by:

$$\frac{T_\mathrm{total}}{T_{s}}={1+\frac{\gamma -1}{2}M_a^2}$$

Since the measurement probe may not recover all the energy from the adiabatic heating a correction factor is introduced:

$$\frac{T_\mathrm{total}}{T_{s}}={1+\frac{\gamma -1}{2}eM_a^2}$$

This 'recovery factor' $e$ is determined empirically for the temperature sensor used.

The display on the EFIS will show the OAT, which may be slightly off if $e$ is not entirely correct. This will also affect the "true" airspeed indication.

To conclude; anything indicated in the cockpit can contain measurement errors, regardless whether it is called 'indicated' or 'true'.

With the introduction of digital flight data systems the error correction tables have been moved from the manuals to the computer, which automatically corrects for them.


(B737s) Why is the automatic activation range of the AUTO mode in flight limited to "between idle and 5%"?

The reason to go automatically to ignition below idle N2 is to try to avoid a flameout. If the engine has slowed down to be at or below 5% N2, it is way too slow for combustion to happen - you don’t add fuel to a normal start until about 25% N2, by comparison. So “below idle in flight” almost is a valid characterization of when AUTO will turn on the igniters, it is just that the bottom of that range stops not at zero but at a slightly higher value. Ignition isn’t going to accomplish anything between 0% and 5% N2 anyway. (Probably can’t accomplish much at 6% or 7% or etc either, but those are probably seen only briefly on the way to, or from, near zero, so the engineers picked 5% as their cutoff.)

Note also that some switches are

GRD-OFF-CONT-FLT

While others are

GRD-AUTO-CONT-FLT

So, for the switch with an “AUTO” position, there is no other “OFF” position, so there needs to be a cue to the system to turn the igniters off, rather than to let them run continuously on a shut-down motor. And rather than saying simply that OFF happens at 0.0% N2, they’ve specified a range, so that the igniters can be turned off for a shut-down but still slowly turning (windmilling N1) motor.


Why are the engines on the MAX and neo prone to bowing?

Rotor bowing is not unique to this generation of engines. It was an issue with the early IAE V2500. I remember initially they would have somebody manually rotate the fan some time after shutdown. This engine still has a longer start motoring period over the comparable CFM.

The root cause is simply making the shafts thinner, increasing their flexibility. When natural differential cooling occurs, they bow. This is done in the pursuit of weight reduction, which is important as new engines are larger and heavier than before.

The PW1000G is a special case, which is where the majority of the issues are occurring. Because of the fan gearbox, the fan operates at a slower speed than the core. Thus, for the same amount of power, the core will spin faster with less torque. The thickness of the shafts are only dependent on torque and not speed, so Pratt and Whitney was able to thin the shafts significantly and cut weight. Unfortunately, they did not properly account for rotor bowing.


Can a commercial cargo aircraft be converted into a commercial passenger aircraft, and vice versa?

There are such a thing as "Quick Change" aircraft, allowing entire 'pallets' of chairs to be exchanged for cargo.

Image courtesy of canalblog.com

Image courtesy of airliner.net

Nice film to show the process.

Military transport aircraft can also be fitted out with stretchers or seats, or whatever other combo of stuff you want. To the best of my understanding these lock in like any other cargo pallet in the floor. They are less concerned with aesthetics and more with practicality:

Image courtesy the DOD via Wikimedia

Image courtesy of aarcorp.com


Why aren't there more stringent checks for switching off electronic devices during takeoff-landing?

There are some problems with this as electronic equipment are not banned in aircraft per se, but only during some (critical) phases of flight.

First, how to determine if someone is operating electronic instruments. It'll be difficult, considering that everyone is seated. The only way is to put a lot of cameras (who's going to monitor them?) or by asking everyone to check their fellow passengers, hardly a good option.
Even if someone operating an electronic equipment is detected, what to do? During takeoff and landing, seat belts are mandatory and the only option (except announcing the seat number over PA) is to ask the person in nearby seat to snatch the offending equipment; again not a good solution.

As most of the electronic equipment (like camera or music players) emit little radiation and no air crash has been attributed to use of electronic devices, I doubt airlines will do something to physically to prevent passengers from using electronics.


Can an airline reject a passenger for being overweight?

Yes.  If carriage of said person on a particular flight would cause the aircraft to be overloaded or outside of its CG envelope, the airline has full right to refuse them passage for safety reasons. It would be illegal under Part 121 and Part 135 to do otherwise.

Practically speaking though, most large commercial aircraft have such great payloads that this would not happen on a frequent basis.  Now the airlines may charge said person for an additional seat costs because of their size and girth.


Do any countries besides the USA accept Basic Med?

(I've made this a community wiki answer so that others can add new information if/when things change.)

These countries allow US pilots to fly with BasicMed:

The Bahamas
Mexico (from 10 Dec 2019)


Is there an upper age limit for pilots freight only?

The only situation in which a US-licensed pilot is subject to an age limit is part 121 scheduled airline service. Other than that there are no age limits, you just have to be able to pass your medical exam.

However, you state that in your scenario the pilot will have to be able to fly cargo in and out of the US. That implies the pilot may have a foreign license, in which case you must refer to that country's regulations.


Is it permitted to load a full cargo container onto an aircraft without a roller track loading/locking system?

(I just saw you asked about Europe right as I posted this, if this is not applicable any more I will remove it)

If Im reading this correctly the question is asking "how is cargo secured if not loaded through the use of a Unit Load Device (ULD)"

Here in the US under the FAA there are some guide lines for tying down cargo if no ULD is present. You can read them here (SAFO 13008) and here (SAFO 13005). Much of the over arching information can be found in this Advisory Circular On Air Cargo Operations (AC 120-85).

In short,

  ...The manual must state the policy and provide procedures to determine
  the intended reaction load for each tie down to ensure sufficient
  special load restraint for flight loads...

You can tie it down as long as you conform to the above linked documents and ensure the straps and tie downs are sufficient to hold the cargo.


Why are follow-me cars used in Gran Canaria Airport in good visibility for incoming aircraft?

The unspoken truth (no references, sorry) for this also applies to many airports around the world (not just Gran Canaria). The follow-me service is not free, and it's one of the ways airport operators make money and create jobs for the community.

The Spanish Aeronautical Information Publication (.pdf) for GCLP does not state a reason, merely confirms what you saw, a follow me for all arrivals regardless of LVP. Here's an example of such paragraph:

  ATC clearance to land at RWY 03L, leave runway via TWY R1R or R1L, following TWY R2 and wait for ATC clearance to enter apron via Gate J, following the instructions of "FOLLOW ME" vehicle, via TWY R10 to the stand (...)

Also see a related discussion on pprune.org.


What causes harsh noise during TX/RX on VHF radio?

If the transmit signal is strong the Signal-to-Noise Ratio is high, which would mean that the noise that you hear is not background white noise filtered through the VHF frequency band. First thing I would look for is an active noise transmitter on the band, which would only be present in a limited set of frequencies.

Hard to say from behind the keyboard what causes the noise that you hear, suggestions for troubleshooting:

Is the noise present at all Xmit frequencies?
Does it diminish if you move away from your present position?
Does your squelch setting help at all?


What is this plane spotted from Outer Banks, NC?

(USAF)

Judging by the single pair of pylon tanks, DIRCM (Directed InfraRed Counter Measure) heads near the tail and lack of armament on left side, and what looks like 4 bladed props, it is likely an MC-130H.


How much earlier/later is sunrise/sunset at 40,000 feet?

There's two parts to the answer.  One is the extra angular distance to the sun you get from altitude and the other is the time that it would take to traverse that distance.

For the angular distance, besides the surface geometry, there's some additional effects of refraction.  I'm going to ignore that on the assumption that there will be some refraction both at the surface and at altitude, so it will mostly cancel out (and it's harder to calculate it).

From the surface we see the sun cross a line of 90 degrees to the vertical (horizontal), from 40,000 feet it would be $\sin^{-1}(\frac{R}{R + 40,000 \text{feet}})$ or 86.5 degrees.  From altitude, we see around an extra 3.5 degrees.

The time you get from that extra distance depends on the season and the latitude.  If you were doing it over the arctic circle in december, you might get hours or days more sunlight.

If you have time to look it up, check the civil twilight calculator for your location.  That's the time when the sun is 6 degrees below the horizon.  That means you'd see sunset at that altitude about the midpoint of civil twilight.

Otherwise, you can make a broad guess that most places in mid-latitudes have a civil twilight that lasts about half an hour.  So at altitude, you get about 15 more minutes.  Maybe a couple minutes more near solstices, a couple minutes less near equinoxes.


What is this tube-like thing protruding from under an A330's wing?

It is the port for mid-air fuel jettison.

(Image credit: http://opilotoprofissional.blogspot.hk/2011/08/consideracoes-sobre-overweight-landing.html)

The A330 is a long range airliner, capable of serving flight routes that are 10~12 hours long. It is equipped to dump fuel while in-flight to reduce its landing weight.

The A320 is not a long range airliner, thus there is no need to install such equipment on it.


How does GPS measure any plane's ground speed?

GPS is primarily made to determine the position of the receiver.
Therefore, GPS uses several satellites with exactly known positions which send very precisely timed signals. From the time difference between the signals when arriving at the receiver, the own position in space can be calculate, typically given in earths coordinate system.

Get the position two times, calculate distance, divide by time difference, and you have speed.

Another way is to measure the frequency of the signals from the satellites, since it slightly varies with speed due to the Doppler effect. This is similar to the shift in pitch of the horn of a police car passing you.
This method gives you a speed value directly with your position.

As side note:
GPS often is not that precise and gives your position with some offset. BUT the offset is mostly constant, so while the position is not correct, the distance traveled and so the speed is.


Who can sign off the aircraft after completion of 100-Hour Inspection?

Yes.
In the United States, annual inspections must be signed off by an IA, but 100-hour inspections may be signed off by the A&P that performed the inspection.


Yes, they use a chemical to clean aircraft. Back when I was in the Air Force, we used PD-680 type II.

I'm pretty sure they don't use that any more though. PD-680 was discontinued (at least for most applications) around the turn of the century. Most applications that used to use PD-680 switched to PRF-680. I can't guarantee it, but I'd guess that's what they use to clean aircraft.


What is the difference between a crabbed and de-crab landing?

Consider where the center of gravity is in relation to the main wheels. If you are in a tail dragger, you definitely would prefer to de-crab (never heard that term before now) before touching down. If you touched down while crabbed, you'd have a moment created by the center of gravity around the main gear to ground loop the airplane.

In a tricycle gear airplane, that same moment would work to straighten the airplane since the center of gravity is forward of the main gear.

In a crosswind from the right, for example, when you apply left rudder to align the aircraft with the runway, the right wing will want to come up (you just gave it a little extra speed), so you will want to use right aileron to at least counter that as you certainly don't want the crosswind component to get 'under' the wing.

Both 747 operators I flew for recommended touching down in the crab. Personally I didn't like that and used a combination approach in a heavy crosswind, take out some of the crab but not all. Also, while they did caution against lowering the upwind wing, I always lowered the wing a little. I once figured out how much the wing would have to be lowered before ground contact, and it was quite substantial, more than I would ever think of using. Also, as I remember, It would not be the wingtip or an outboard engine pod that would make first contact, but rather the outboard corner of the outboard wing flap when set to flaps 30.

Finally, when your touch down speed is 140 knots, for example, you'll have to crab much less for a given crosswind component than if your touchdown speed is 70 knots. Cosine or tangent of the angle, I forget which.


You could fly gliders. They don't use leaded fuel. In fact, they don't use fuel at all.


Why are high-g requirements so important for training next generation of fighter pilots?

Two solid reasons: defensive and offensive ACM/BFM remain relevant

I'll address the defensive issue first.  Even if a pilot will never get into a dogfight, the pilot / aircraft still must defeat or evade a surface-to-air or air-to- air missile.  This combines the use of both countermeasures and 3-dimensional maneuvering to cause the guidance system inside the missile to lose it's lock on the aircraft.  To get the turn rate and axis-change-rate needed to deal with modern missiles requires the ability to pull a significant number of g's.  You can look at is as a "purely defensive dogfight" technique.  You fight the way you train, so you need to train for this likely situation.

The offensive high energy, high-g capability has to be retained because in real life, the rules of engagement do not always allow for a BVR (Beyond Visual Range) engagement.  Further that point, even with BVR engagements allowed, if the opponent has good defensive technique versus your missiles you may still get into a dogfight-style of engagement in order to defeat or destroy that opponent.  You have to know how to do that, and train for how to do that.  It is an acquired skill. (The basics of the skill were eloquently laid out by John Boyd, which is where the OODA loop model comes from).

Both the offensive and defensive applications of these maneuvers require skill with and acclimatization with high-g maneuvering.

A related reason to boost the performance of the Trainer

For the last 20 years, it has become fashionable, and sometimes useful, to do a thing called "downloading training" into a cheaper to fly, cheaper to maintain aircraft.  That way you don't wear out the airframes of your very expensive front line aircraft.  (The Navy spent years using the T-2 for spin training for its jet pilots, to include T-2's not used in the Training Command but retained on both coasts as "spin birds").   This concept of "downloading training" sounds nice, but in reality has mixed results.  At the high performance level that front line aircraft operate, some skills are transferable and some are "building block" from one airframe to a more complex airframe. Given how recent this requirement is, I'll see in this requirements crafting something similar to the initiatives that I ran into in the Navy (and in Joint Training) with "downloading training."  The same mind set is at work here: if the spec can be met at a high enough level, the graduate of the advanced jet training will enter the front line units with a higher level of capability.   We successfully down loaded quite a bit of instrument training into the sim in at least one aircraft program I worked on, the T-6.  While that was 15+ years ago, the never ending push to "do it cheaper" has not let up in the DoD. Our efforts to download ACM/BFM into the T-6 for the NFO training pipeline ran into the problem of "not enough energy."  I am not sure if that has since been solved, or abandoned, but I think it's the latter.  (The last time I checked on this was about 6 years ago).

Note: This is an experience based answer, informed by my having both been taught basic one-versus-one maneuvering, and many years later having been deeply involved in training systems development, and training requirements, for US Navy fighter/jet pilots. (They had the same challenges to overcome as their Air Force colleagues in the proposed T-X system).  A more detailed answer would be, roughly, book length.  Chapters 5 and 6 of the link cover Offensive and Defensive BFM basics.

From the introduction to that manual:

  BFM INTRODUCTION
  When the P-80 finally became operational in the mid-1940s, WWII was coming to a close, as was seemingly the age of aerial dog fighting. While these aircraft never took part during operations in Europe, they became an integral part of combat operations in Korea. In November, 1950, a P-80 flown by LT Russell Brown shot down a Russian MiG-15 in the world’s first decisive all-jet aerial battle, acting as a reminder that BFM was still a very real possibility in combat operations. With the maturation of aerial warfare evolving into Beyond Visual Range (BVR), the decades that followed Korea exploded with the development and implementation of long range air-to-air missiles that could potentially eliminate the possibility of Within Visual Range (WVR) engagements. During the Vietnam conflict, however, aircrew often found themselves unable to employ their BVR missiles, forcing weapons employment into the WVR arena, ultimately relying on BFM skills to defeat their opponents. The days of Korea and Vietnam are long past, and we have achieved amazing successes with the accuracy and reliability of our current long-range
  missiles.  As we, and our enemies, continue to improve our BVR capabilities, a combination of electronic attack, theater Rules of Engagement (ROE), switchology failures, or a momentary lack of attention to prescribed air-to-air timelines may ultimately bring us face to face with the enemy in a 1v1 engagement.
  (CNATRA P-1289 (Rev. 01-16))

The airframe may change, but the problem remains the same.


How is lift provided by a wing affected by propeller wake?

It both increases and decreases, depending on the local direction of the propellor (e.g. on the upgoing side, or the downgoing side) . See for example this PhD thesis: Propeller Wing Aerodynamic Interference.

This thesis shows the following image:

Simply said, the velocity of the propellor locally changes the angle of attack, and thus the lift generated by the wing.
It is interesting to know that it is possible to locally optimize the shape of the wing to take advantage of this effect. Again the thesis shows the result, and it looks like this:

If you look closely, you can see that the wing is changed at the propellor location to accomodate the adjusted flow.


When do conditions permit doing a controlled fly-by over the runway of a commercial airport?

Essentially a flyby over the runway is nothing more than a planned and prepared go-around from a low altitude. If you say it is a stunt then it probably is not allowed under most legislations. And because of noise regulations airports aren't too happy with the manoeuvre either.
However, nobody will stop you from going around if you "forget" to put your gear down.
I have been in the cockpit on several flybys at several airports, all of them were dressed like a missed approach / go-around along the following lines:

Pilot > "Tower, Hotshot01, requesting permission for a flyby over runway XX
Tower > Negative Hotshot01, you know we can't allow that any longer due to noise restrictions. I can't prevent you from making a go around though! Cleared to land RWY XX.
Pilot > Hmm... ok, cleared to land, Hotshot01

<Hotshot 01 approaches the threshold and applies full power>

Pilot > Hotshot01, going around.
Tower > You owe me a beer now! .. <vectors back to final approach / final destination>


How can adverse maneuverability due to a fuel tank behind the rear pressure bulkhead be mitigated in Airbus ZeroE hydrogen plane?

Airbus will store hydrogen by chemically binding it to carbon for a looong time. This way, it can be put into the wings, a belly tank and the horizontal tail and its gradual disappearance during the flight will not shift the center of gravity much.
What the PR department just published is just for political correctness. It has not been thoroughly checked for practicability by the engineering department. Nobody seriously expects to use hydrogen for airliners. The problems of storage are obviously putting it at a huge disadvantage, and your correctly identified issue of storing fuel far from the center of gravity is one of those problems.
When an Airbus is delivered today, its tanks are filled with a blend  containing hydrocarbons from a carbon neutral source. Beluga flights delivering parts between the Airbus plants use this fuel. Virgin Airlines tested a renewable fuel already in 2008 and Lufthansa flights departing from Frankfurt also use it.
Of course, most airlines will refill with regular, mineral oil based kerosene after this fuel has been used up because it is cheaper and availability is much better. But technically there is nothing holding back airlines today to use a carbon-neutral fuel.
Generating hydrogen today is mostly done using natural gas which is not quite as carbon intensive as kerosene but everything but carbon-neutral. Also, the energy source for refining and transporting fuel from renewable sources will make them less than 100% carbon neutral. The current sources for renewable fuels (plant oils and waste materials) are less than optimal and hard to scale up, but work on using direct sequestration from atmospheric carbon dioxide is progressing. Today, we waste excess solar power by shorting it to ground. I know better uses for that excess energy …


Aerodynamic Pressure Loads in FEA of Lifting Surfaces - Query

There is fuel inside the wing, and there is definitely a connection with the outside atmosphere for venting while fuel is flowing into the engines. The fuel tanks are sealed from the outside airflow. In a document about the B737NG from Smartcockpit.com (now via Scribd) it says:

  The purpose of the fuel vent system is to prevent damage to the wings due to excessive buildup of positive or negative pressure inside the fuel tanks and to provide ram air pressure within the tanks. The tanks are vented into surge tanks which vent through a single opening at each wing tip.

A recent development, long recommended by the NTSB but deemed too expensive to mandate by the FAA, from this site:

  Boeing has developed a Nitrogen Generating System (NGS) which decreases the flammability exposure of the center wing tank to a level equivalent to or less than the main wing tanks. The NGS is an onboard inert gas system that uses an air separation module (ASM) to separate oxygen and nitrogen from the air. After the two components of the air are separated, the nitrogen enriched air (NEA) is supplied to the center wing tank and the oxygen enriched air (OEA) is vented overboard. NEA is produced in sufficient quantities, during most conditions, to decrease the oxygen content to a level where the air volume ... will not support combustion. The FAA Technical Center has determined that an oxygen level of 12% is sufficient to prevent ignition,


What is the life limit due to metal fatigue in large bombers?

Metal fatigue and fatigue corrosion are and have been a problem since the type's introduction. They always fatigue and corrode, they always undergo expensive repairs due to corrosion. DIEGME degradation of fuel tanks has been a particular culprit, and it has been reduced with new coatings.
Bombers aren't pressurized, so the whole fuselage doesn't fatigue the way it does for airliners. The hard limit for wing spars fatigue can run into the centuries, considering that these planes don't fly all that much.
100 years is a bit of an exaggeration. The oldest B-52 in service come from the late 50s to 1962, when the production ended. So at retirement time the planes will be just 90 years old. There is a lot of B-52s sitting idle in storage, since they used to be considered strategic and fell under SALT cuts, and they're available both as spare part sources and as restorable airframes.
Why shouldn't a 100 year old plane fly? The USS Constitution is 220 years old and she's still sailing the seas, a considerably more hostile environment. It took a lot of restoration, but not quite to the extent of the Theseus' ship. Not everything is built with planned obsolescence like cars or iphones; ships and planes are built to last, as long as the owner spends the money needed to keep them up.
Keeping the old planes intact may not be cheap, but new bombers are far more expensive. The B-1B is half a billion a piece, so is the Tu-160. At the same time, most of the work the USAF does is milk runs in a threat-free environment. It doesn't call for advanced supersonic or stealth machines, it calls for something that's easy to service and cheap to run. The B-52 fits the bill better than any other bomber the USAF has. The only extant competitor is the Tu-95.
The B-52 can in theory be replaced by something even cheaper to run. Plenty of Boeing manufacturing capacity will sit idle for a long time, and, given a supply of olive drab, they'd fit the job even better. But this can't happen, because every military procurement program since the WW2 begins and ends with feature creep, doubly so in the Air Force. Only existing inventory can be kept as simple as it is.

All of this essentially leaves no choice but to keep up the current planes. Aluminum is cheap, it's silicon that's expensive, and B-52s have very little of that.


Why do fighter jets pilots use an oxygen mask?

the pressurization system in a fighter plane might be able to furnish 10,000 ft cabin altitude at 30,000 feet, but the pilot would need supplemental oxygen when flying higher than that. In addition, if the cabin is breached above 30,000 ft the pilot would have very little time to get his or her mask on before blacking out, so the mask is worn at all times.


How do you know if a VOR is High, Low, or Terminal?

The range of the VOR is included in the Airport/Facility Directory data under the name class
From A/FD legend:

Example:

Service volume for each class:


How did NASA Langley end up with the first 737?

NASA has lots of cool aircraft. They get them sometimes when they get to the end of their life/retired, sometimes they are custom built trainers, and sometimes they are used to test research projects. You can find the full history of that particular 737 here

  NASA’s Boeing 737-100 Transport Systems Research Vehicle was the
  prototype 737, acquired by the Langley Research Center in 1974 to
  conduct research into advanced transport aircraft technologies.

  ...

  The Boeing
  737 was Langley's number one choice, however,
  since it had a slightly wider fuselage and an
  advanced, high-lift flap system. Money however, was extremely tight. The
  market value of a used 737 in 1972 was about $3.5 million, but the
  Boeing Company had one particular 737 that its sales people said they
  might be willing to sell for substantially less."

  ...

  Boeing had designated the prototype as PA-099: PA for Lufthansa, and
  099 as the last one in a block of 100 aircraft numbers Boeing had
  reserved for the airline. The prototype was never sold, however,
  because it was only certified for experimental use. With all the
  holes, wiring and other modifications that were made to the airplane
  for certification tests, bringing it up to the standards of a
  commercial transport airplane would have been too expensive. Boeing
  used the airplane for a few additional flight tests and then simply
  set it aside. '

In short, it was cheap, couldn't be used for commercial flight, and just what NASA needed. Chapter 2 in the above linked document covers the history in more depth and explains more of the nuances of the deal. To keep from copying the whole text I'll end it here.


Why are F-15s usually taking off with afterburners?

To be sure to not use more runway than available.
It is also good to have runway to spare in case take-off has to be aborted.
Look at this image as an example from another fighter. Notice the two X-axis. The top MIL is for without afterburner and the bottom FULL AB is with afterburner. Notice how the numbers for the MIL is almost double that of the FULL AB axis. That means much (a little less than the factor difference between the two numbers) more runway required for same conditions. And in case your wondering, that number depends on runway temperature and altitude above sea-level beside from thrust setting.


How can I calculate the angle of attack of an airfoil?

The angle of attack is the angle between the wing and the direction of flight. The direction of flight is opposite to the airflow, so the angle of attack is also the angle between the wing and the relative wind.

For a more refined definition (thanks @Peter Kämpf): The flight path direction (the velocity vector in the language of aerodynamicists) should be expressed relative to the air mass, not to the ground (as measured by an inertial system), but that's beyond the topic.

How to compute it? Well, it's like airspeed, we don't. It's just measured using a small windvane:

A380 angle of attack sensor (combined with a Pitot-static), source

In the image above, the black angle of attack sensor is combined with a classic Pitot-static which measures airspeed. On airliners, there are usually several AOA sensors. The one in the picture is located on the FO side, air comes from the right side.

Another simple AOA sensor at the bottom, Captain side:

Source (original source not found)

There is a specific AOA sensor found on GA aircraft, to trigger an alarm when approaching the critical angle of attack: The stall sensor:

Source

This strip located at the wing leading edge has two positions and rock abruptly before the critical angle of attack is reached. It triggers an alarm in the cockpit, so that the pilot can reduce the angle of attack.

A final note: The AOA wasn't displayed to the crew in the cockpit, only the pitch angle was. Newer aircraft now display both. I think it was a recommendation of the BEA after AF447 accident, were the crew couldn't figure out the AOA they were at after a Pitot-static froze.


What prevents the use of a multi-segment ILS for non-straight approaches?

See here, pages 5-23, 5-24.  Things have advanced well beyond ILS for that kind of approach.

https://whispertrack.com/pdf/faa_handbook.pdf

  REQUIRED NAVIGATION PERFORMANCE
  The operational advantages of RNP include accuracy
  and integrity monitoring, which provide more precision and lower minimums than conventional RNAV.
  RNP DAs can be as low as 250 feet with visibilities as
  low as 3/4 SM. Besides lower minimums, the benefits
  of RNP include improved obstacle clearance limits, as
  well as reduced pilot workload. When RNP-capable
  aircraft fly an accurate, repeatable path, ATC can be
  confident that these aircraft will be at a specific position, thus maximizing safety and increasing capacity

  To attain the benefits of RNP approach procedures, a
  key component is curved flight tracks. Constant radius
  turns around a fix are called “radius-to-fix legs,” or RF
  legs. These turns, which are encoded into the navigation database, allow the aircraft to avoid critical areas
  of terrain or conflicting airspace while preserving positional accuracy by maintaining precise, positive course
  guidance along the curved track. The introduction of
  RF legs into the design of terminal RNAV procedures
  results in improved use of airspace and allows procedures to be developed to and from runways that are otherwise limited to traditional linear flight paths or, in
  some cases, not served by an IFR procedure at all.
  Navigation systems with RF capability are a prerequisite to flying a procedure that includes an RF leg. Refer
  to the notes box of the pilot briefing portion of the
  approach chart in figure 5-17.

The Approach in Fig 5-17 has 5 turns left & right!


Is it legal to takeoff in a crosswind that exceeds the design limit of my aircraft?

The 15kt crosswind for the 182 is not a design limit at all. If it were a design limit, it would be specifically stated in the POH. To be honest, I think there's no such thing as a design limit for crosswind. It all comes down to how much rudder authority there's left at a specific crosswind strength. And even that depends on many factors like approach speed, flap settings, weight, CG, etc.

This is what the POH for the C182T says:

  Demonstrated Crosswind Velocity is the velocity of the crosswind
  component for which adequate control of the airplane during takeoff
  and landing was actually demonstrated during certification tests. The
  value shown is not considered to be limiting.

and:

  The maximum allowable crosswind velocity is dependent upon pilot
  capability as well as airplane limitations. Operation in direct
  crosswinds of 15 knots has been demonstrated

So it is perfectly legal to land and takeoff with a stronger crosswind component. It's up to the pilot to determine if it's safe to do so or not. It all depends what the pilot's capabilities are.


Is this legal for transportation in the US? (video in description)

In class G airspace provided proper separation from people and buildings you should be good to go. The airspace you are in can be determined by geographic location and altitude using the FAA's charts you can find here.

  legal for transportation.

This is a somewhat broad term. The FAA may require you to get it set up as an experimental aircraft but thats up to them. If you plan to do more than hop around empty farms and over a pond you may want to contact your local FSDO for a ruling on what you can do. You can also reach out directly to the FAA for a ruling on a specific question.

The FAA as per

  § 1.1 General definitions.

  ....

  Aircraft means a device that is used or intended to be used for flight in the air.

does define what you show as an aircraft and would most likely see it as falling under their purview.

Note that since he is over open water he has a life jacket on board (although he is within the required 50 miles and technically does not need one). He also has a chute presumably for emergencies.


Does total aerodynamic force include skin friction/shear streses contribution?

Yes.  Skin shear, due to friction between the airflow and the skin, is one way how force is transmitted from the airflow to the solid body.  The pressure distribution is the other main way.  If a definition of total aerodynamic force excluded one of these, it would be incomplete.
One way to think of total aerodynamic force is to just measure it, period.  It is what it is.  Another way is to try to split it up into its parts and put it back together again.  The second way is less accurate, but more useful for theory and modeling.


What determines the direction of rotation for counter-rotating propellers?

Most twin-engine aircraft with counter-rotating propellers have the rotation set up so that the propellers are rotating inward towards the center at the tops of the propeller arc.

This configuration reduces the P-Factor effect at slow speed high angles of attack, and eliminates the "critical" engine that is present on multi-engine aircraft where both engines rotate in the same direction.

Conventional Multi engine propeller aircraft (both clockwise rotation)

The original XP-38 (X=Experimental) had "inward" counter rotating propellers but only flew a few times before it was destroyed in a crash.

There were some tail buffeting problems identified with the XP-38. While trying to solve the tail buffeting problems, various wind tunnel tests were conducted. Some of these tests were done with "outward" rotating propellers.

These tests showed that "outward" rotating propellers did not reduce tail buffeting BUT they did reduce power on/power off pitching moments, and therefore made for a more stable gun platform.

  "The P-38 props rotate in the direction they do for the simple reason it reduced the power on/off pitching moment, thus making for a more stable gun platform" - Kelly Johnson, P-38 designer.

The tail buffeting was eventually solved by fitting large leading edge fillets at the wing/fuselage interface.

The YP-38 (Y=Prototype) and most subsequent versions of the P-38 retained the "outward" counter rotating propellers. This in effect made both engines "critical", but combat performance was more important that low speed performance.

So while most aircraft with counter rotating propellers have "inward" rotation, a few do have "outward" rotation to gain an operational advantage.


What are the safety concerns and efficiency benefits of two in-line runways?

How to ensure the planes landing and take-off in the same runways safety?

No one knows.

Note this isn't exactly what is being proposed

  By dividing it in two with a generous central buffer zone, we create two in-line runways, allowing aircraft to simultaneously land on one and take off on the other.

So that isn't simultaneous landing and taking off on the same runway.

Currently only one LHR runway is used for take-offs at any time. The runway is switched to provide respite from noise to local residents in the take-off path.

Also the surrounding airspace isn't set up in a way that would allow separation for concurrent take-off from two runways. A major reorganisation would be needed of airspace in that region of the UK.

I believe that currently, simultaneous take-off require parallel runways a mile or more apart.

  How many flight can be handled by such design

No one knows. Maybe a c 46% increase from 480,000 to 700,000 air transport movements a year. See reference below. Bear in mind that Heathrow is subject to a night-time curfew.

  How efficient is it compared to parallel runways?

No one knows.

According to the airports commission in 2014:

  The concept of an in-line runway is unconventional, has never been used elsewhare and is not envisaged in international, EU or national regulatory instruments, standards or recommendations for safe design or operation.


BNR labels that can be negative are represented in 2's complement form
2.3.1.1 Numeric Data

The Mark 33 DITS should accommodate numeric data
encoded in two digital languages, (i) BNR expressed in
twos complement fractional notation and (ii) BCD per the
numerical subset of ISO Alphabet Number 5

If your label is indicating 7 significant bits and an LSB of 1, your range must be +/-128. Bit 29 is the sign bit, and the data bits work down from there.

-1 = 1 1 1 | 1 1 1 1 | 1 0 0 0 | 0 0 0 0 | 0 0 0 0


For IFR flights that require two alternates, is there a regulation that requires enough fuel to reach the furthest one?

EASA OPS 1.255, appendix 1, 1.4 b).

I don't have the text in English here, sorry.


How can I calculate the Obstacle Free Zone of an aerodrome?

AS per ICAO Annex 14, Obstacle free zone (OFZ). The airspace above the inner approach surface, inner transitional surfaces, and balked landing surface and that portion of the strip bounded by these surfaces, which is not penetrated by any fixed obstacle other than a low-mass and frangibly mounted one required for air navigation purposes.

For easiness it is a rectangular area around the runway which extends 60M for Code 4E runway and 77.5M for Code 4F runway from runway centre line sideways and 60M from the runway thresholds.


Does ADS-B In receive track or heading angles?

It is the true track angle.

True means with respect to the geographic North (as opposed to the magnetic North)
Track angle means the direction of motion in the horizontal plane (as opposed to heading, which means the direction of the projection of the primary body axis in the horizontal plane).

Track angle can be derived from a line joining successive position points, but that is not typically how its done. GPS commonly uses a combination of Kalman filtered change of position combined with (Kalman filtered) velocity derived from Doppler shifts.

For ADS-B In, the track angle is just what is reported by ADS-B Out. It does not involve processing successive position reports.


How to identify the FAP in runway during Landing?

The final approach point is part of an instrument approach and thus can be identified using navaids as outlined in the approach procedure.


What is a SAAAR / RNP AR instrument approach?

First allow me to give a quick introduction to RNAV and RNP before geting to SAAAR / RNP AR.

Area Navigation (RNAV) is a method of instrument flight rules (IFR) navigation that allows an aircraft to fly on any desired path within the coverage of referenced navigation beacons, rather than navigating directly to and from the beacons. In other words, waypoints can be defined at arbitrary locations and paths betweens those points (and traditional navigation beacons as well) can be defined.

RNAV routes are coded into the navigation database by ARINC 424 path-terminators. Whilst RNAV routes can be designed in such a way that the lateral path is strictly described, in general the lateral path has a quite some freedom due to floating leg types (e.g. turn at altitude, fly heading etc) and wiggle room for the aircraft to negotiate the turns.

When the route is described only by TF (track to fix) and RF (radius to fix) path terminators, the lateral path is fully fixed. These fixed lateral paths allow procedure designers, for example, to design approaches through mountain valleys down to the runway.

RNAV defines a 95% accuracy bounds. For example, RNAV 1 requires the aircraft to be within 1 NM from the path centreline 95% of the time. The route designer will ensure a 2 NM obstacle free zone around the path in such a case.

Note that RNAV provides no assurance against exceeding the 2 NM zone. There is no automated system monitoring required.

Potentially causes of deviations between the path intended by the procedure designer and the actual flown path can be grouped into three categories:

First, there is the Path Definition Error. This is caused by database
coding mismatch with the original path design.
Second, there is the Path Steering Error, caused by the combination
of display inaccuracies on the Navigation Display and the inability
of the pilot or the autoflight system to stay exactly on path (Flight
Technical Error).
Third, there is Position Estimation Error, which is the difference between the position of the aircraft estimated by the navigation system and the true position.

It is not unthinkable that while normally (95% of the time) the aircraft will fly within e.g. 1 NM of the intended centre line, there are cases that the aircraft will exceed the 1NM by far, possibly even busting the 2 NM obstacle free zone. That could potentially ruin your day if it happens in a mountain valley.

This is where RNP comes in. RNP (Required Navigation Performance) is basically RNAV with added protection. For example, RNP 1 again defines a 1NM accuracy for 95% of the time, but it also offers 99.999% assurance that it will not exceed the 2NM. It will raise an alert if the 2 NM value will potentially be exceeded. So in addition to what RNAV offers, it includes a system monitoring function that will detect navigation errors and alerts for them.

The RNP value alway gives the 95% accuracy, the 99.999% assurance (integrity) limit is always at twice that value. So RNP 0.3 means that the aircraft has to stay within 0.3 NM of the designed path centreline 95% of the time. And if it exceeds the 0.6 NM threshold, an alert will be raised with 99.999% certainty.
RNP systems therefore require a system monitoring function.

To ensure that the RNP values are met, each of the three error sources mentioned earlier must be under control. For RNP values down to 1 NM that is not much of a challenge. Standard procedures and equipment are deemed to be sufficient here. (of course the required RNP values must be met by the Actual Navigation Performance)

If an approach requires tighter limits, such as RNP 0.3 or 0.15, then special authorization is required.
This is where SAAAR comes in (Special Aircraft and Aircrew Authorization Required), now renamed to RNP AR (RNP Authorization Required). RNP AR routes only make use of TF and RF leg types to fully fix the lateral path. RF legs are not supported by all navigation systems by default.

To get authorization for RNP AR, the aircraft needs to comply with the applicable functional and performance requirements, the crew needs to be trained and lot's of documentation must be maintained. Basically proof must be provided that all of the three error terms are under strict control.

In a sense it is somewhat similar to ILS CAT III approval.

References:

AC 90-101A describes a means of compliance for RNP AR

RNAV / RNP presentation gives a good explanation of RNAV and RNP


How do I convert true heading to magnetic heading or the other way around?

Short answer: Yes there is, but it doesn't always work, it involves a LOT of math, and you're probably not gonna like it.

Medium Answer: Most flight planning software incorporates a True/Magnetic heading conversion system (ForeFlight for example).
Using an electronic flight planning tool like this is probably your best bet if you want an on-the-fly determination made for you.

Long answer:
International Association of Geomagnetism and Aeronomy (now there's a mouthful!) periodically publishes what's known as "International Geomagnetic Reference Field (IGRF)".  It's a mathematical model of Earth's geomagnetic field, which you can work from some exceptionally complicated trigonometry (or just look up the coefficients in a table which is what most sane folks do).
If reading text like "Mathematically, the IGRF model consists of the Gauss coefficients which define a spherical harmonic expansion of the magnetic scalar potential." makes your eyes roll back into your head (I was a math nerd and it makes MINE roll back!) using the model is probably not for you.
If your eyes are still focused on this text however, click on through to that link way back at the top of my answer and you'll be rewarded with a formula you can plug into your trusty calculator.


How can hang gliders and paraglider pilots prevent stall?

Paraglider pilots learn "active flying", whereby you use feedback from the wing to determine what's going on. You monitor the tension in both controls (the "brakes"), and the wing's attitude (if the wing pitches forwards then you feel like you are swinging backwards).

In bumpy air (such as on the edges of thermals, or in wave) active flying is used to keep the wing more or less above your head. If the wing surges forwards then you risk a collapse; if the wing falls back then you risk a stall.

In smooth air a stall is only likely if you are pulling the brakes down too far. This can happen accidentally, especially in nil-wind landings if you mistake your ground speed for airspeed.


Is there a regulation against having uncaged dogs or other animals as passengers on private aircraft?

It appears that the answer is "there is no such regulation". For example, from AOPA's Flying with Family:

  Airlines require that any animal on board be confined to an animal carrier at all times. Although there are no such requirements for general aviation aircraft, it is always better to err on the side of safety and keep them in a carrier.


How does engine geometry affect flight stability?

The problem appears to be mostly the effect of a larger cowling, moved more forward, that generates significant lift when operating at higher AOA and has an effect similar to moving the entire wing forward, or moving the center of gravity aft, partially unloading the horizontal tail in the flaps up low speed regime and making the pitch stability a bit neutralish.

Seaplanes suffer from a bit of a similar effect in yaw from adding floats. The floats add quite a lot of side area forward which reduces the fin's weathervaning tendency.  This is why you usually see additional fins added to the tails of float planes to restore the original yaw stability.

In the case of the MAX it appears the pitch destabilizing effect of moving the cowls forward really caught them by surprise because the problems were only found during flight test.  To restore the original relationship of the effective center of lift to CG would have required some pretty radical redesign, say like adding a plug to the forward fuse to move the operating CG forward, which would also require making the tail bigger... and off we go on the one-thing-effects-another design change merry-go-round without end.  What a mess.  They were really between a rock and a hard place, and an artificial stability system using the stab trim system to work around what was a fairly narrowly focused problem provided a relatively easy escape route.


Why can't we see the downwash/wake roll-up behind 2D/wall-to-wall airfoil tests?

Who says we can't? It just needs open eyes and an open mind.
To understand the picture below, keep these things in mind:

If the streamlines are packed together, the flow speed is higher while pressure is lower than ambient.
Conversely, when the streamlines are spaced wide apart, flow speed is lower but pressure is higher.
Converging stream lines mean accelerating flow.
Diverging streamlines mean the flow slows down.

Somehow, the air has to flow around the obstacle that the airfoil represents in a closed wind tunnel. It does so by speeding up (at least in subsonic flow). Conversely, when the airfoil tapers towards the trailing edge and an angle of attack makes the cross section downstream become wider, the air slows down in order to fill the available space. In the end, the mass flow near the suction peak where the cross section left open by the airfoil is narrowest is equal to that near the trailing edge when the cross section has become much larger. The same happens on the lower side: All the air passing below the stagnation line has to squeeze through the gap left between trailing edge and tunnel wall. This is only possible by a large change in speed.
Now have a look at stream lines in a windtunnel. Note that the lines near the upper and lower edge of the picture are almost straight and nearly follow the wall contour of the tunnel (picture source):

The downwash is the downward-pointing part of the streamlines over the rear part of the upper airfoil contour. Due to tunnel wall interference, the flow on the lower side near and especially past the trailing edge is very different from free flow and the air has to speed up to flow through the gap left between the airfoil and the tunnel wall.
You also see the smoke lines past the trailing edge fan out: The flow near the center section of the tunnel is still fast and stays near the bottom while the flow near the wall slows down and bends upwards, causing the lines to spread out. The lines near the wall even intersect the ones near the center! Clearly, this is a 3D effect which resembles the wake rollup past a wing in free flow, but crippled by the proximity of the tunnel wall.
While the air coming off a wing in free flight with attached flow has approximately the same speed over the whole height, here tunnel wall blockage means that the air coming off the lower side is much faster than air coming off the upper side. This is necessary to let the air shift downwards past the airfoil, as it does in the wake of a wing. Of course, the tunnel wall and friction will limit that downward movement, but by adjusting flow speed the tunnel airfoil is able to create a downwash, too.
Another way to look at it: The slow, high pressure air coming off the upper side of the airfoil squeezes the fast, low pressure air coming off the lower side down. Either way, downwash is the result.
The downwash is right there and hard to overlook: The streamlines coming off the airfoil clearly have a downward direction. Wake rollup is also happening, albeit near the right edge of the picture and less pronounced than in free flight. If that is not evidence enough, I don't know what ever will be.
The picture has to be sufficient. Sorry, no movie.


What is the maximum take off climb angle of a Boeing 737 MAX?

That’s a wild demonstration but it’s also not a very realistic  barometer performance for typical 737 operations. The video you see there is a high-performance demonstration flown in an air show or a trade show just for the purposes of entertainment. It involves an airplane that has literally been stripped down of any unnecessary parts, no other personnel or cargo on board except for the minimum required flight crew and barely enough gas to get the performance done and maintain day VFR reserve minimums to get them back to the airport.   The climb there was done in about an angle of 50 to 55° from the horizontal.    Even in these conditions a Boeing 737 does not have a thrust to weight ratio exceeding one and as such the aircraft is in fact slowing down. Still it gives an impressive climb to around 2000 to 3000 feet above the airport for the spectators below.