Because much of the fun in being in a sailplane, is in actually flying the sailplane.  It's not a means to get from point A to point B, it's a means to enjoy the magic of flight, much of which involves seeing the sailplane respond to your control inputs.
Once you start getting more than two occupants, most of the occupants won't get to do much of the flying.
It's kind of like asking, "why aren't there more saddles for horses that can handle 3 or 4 people?"
As an aside, raw novice passengers tend to be at high risk for airsickness when subjected to prolonged thermal turns in turbulent conditions, especially if they get to do little or none of the actual flying.  Three or four non-flying passenger seats would potentially equate to a lot of clean-up afterwards.
I guess it's all a little subjective-- a commercial pilot friend of mine regularly gives 15-to-60 minute semi-aerobatic rides in a glider with room for two passengers squeezed in side-by-side on a seat in the back (Schweizer 2-32), with controls for the pilot only, and most of his passengers love it (and most don't get sick).  But being seated tucked in close to a friend for a little while feels different than riding on a "bus" with, say, four or more strangers-- and in that particular case the very same glider can have the second control stick re-installed in the back and be used for student instruction with one rear-seat occupant and one front-seat occupant.  A bigger "bus" with more ample seating for multiple passengers probably would be a poor candidate for a training glider.


How do internally carried IR missiles acquire a lock?

If you are referring to the Sidewinder missile, the first iteration AIM-9X did not have a requirement to be launched from internal stores, known as captive carry, but in testing it demonstrated that it could lock on after launch. This was deemed interesting enough that Raytheon got a contract for the Block II variant, which among other things adds a datalink capability so that an aircraft with the right equipment can direct the missile to where the target is located, after which it locks on with the IR sensor. This allows it to be used on the F-35, F-22 and even submarine platforms.$^1$

Block III has the same datalink capability (derived from tech developed for the AMRAAM missile) but also has increased range and an insensitive warhead that reduces possibility of accidental detonation on the ground, among other things.

A big reason why the AIM-9 series continues to be upgraded is because of its IR capability. Some countries have developed jamming technology that can interfere with the more modern AIM-120's radar tracking system.

$^1$: Raytheon AIM-9X Block II Missile Completes First Captive Carry Flight, spacewar.com, 2008


What's the difference between aquaplane and hydroplane?

It is the same thing, even wikipedia cross lists them, however in the case of aviation it is both a noun and a verb

Aquaplane

(source)

Aquaplaning

(source)

Non-Aquaplane-AquaAquaplaning

(source)


Why isn't landing in the water a good option in an emergency?

For one you can not "land on water" you can ditch an aircraft in a body of water but you would be hard pressed to call it a landing. You can however, "land in a grass field" or "land on a runway nearby" or "land on a highway" all of which are substantially more controllable then trying to stall a few feet above the ocean.

The result of catching an edge which can dig into the water is the same or worse than belly landing on grass. As others have mentioned at those speeds water is not so forgiving. but historically it tends to end poorly. While the miracle on the Hudson ended well Ethiopian Airlines Flight 961 did not have the same luck. You can see the outcome of contacting asymmetrically is pretty devastating.

The secondary concern is that even in a successful ditching still puts you in a sinking airplane with potentially injured people making rescue all that much harder.

Although Aviation Saftey Magazine paints an interesting counter point.


Why does airflow separate from the wing during stall?

Air flowing underneath the wing at an angle is pushed downwards, regardless of the shape of the lower surface: high pressure has few practical limits.

Air flowing over the upper surface cannot suddenly change direction though because it is driven by an under-pressure gradient. It can follow a slowly curving surface to the limit of the pressure differential between ambient and suction, but too steep a curve and the airflow cannot follow and has to separate: a stall occurs.

Picture source


Will Lockheed Martin Flight Services send me ACAS, EasyActivate™, and other text messages if I file my flight plan through ForeFlight Mobile?

Based on my personal experience, the answer is NO (as of the time of writing). I use both systems regularly, and have discovered the two do not share flight plans at the user account level. ForeFlight uses its own account (and not individual user accounts) to interact with Lockheed Martin Flight Services. Because of this, it appears that LMFS has no way of knowing which user account is associated with a flight plan filed through ForeFlight.

Identifying data within the flight plan itself (i.e., name and phone) are not processed by the filing system, merely stored for later retrieval if needed. I mention this because LMFS can (upon request) associate tail numbers with a phone number, so that when you call them on 800-WX-BRIEF your profile comes up on their screen automatically (though I have found this to be less useful than one might think).

In order to use the services you have identified, you will need to file your flight plan directly on the LMFS web site (and have your notification settings configured properly).

With that said, all of these functions (with the exception SE-SAR), have been available directly within ForeFlight for some time:

ACAS/ATC notices - if configured by the user, sent via push notification (http://blog.foreflight.com/2014/11/24/6-5-brings-flight-notifications-and-notam-advisor/)

EasyActivate/EasyClose - flight plans can be amended/canceled/activated/closed within the File & Brief window (http://blog.foreflight.com/tag/flight-plan-filing/#attachment_4045)

Close reminder - sent via push notification (https://support.foreflight.com/hc/en-us/articles/205052928-What-are-push-notifications-)

Over the past couple of years, ForeFlight has been aggressively working towards tighter integration with LMFS, so I would expect additional functionality to be forthcoming (purely speculative, since they are very tight-lipped about upcoming enhancements).

UPDATE:

It looks like LMFS now offers integrated services with a number of providers (but not ForeFlight). My guess is ForeFlight doesn't allow it because it was already offering the same services and now needs to figure out a way to ensure users don't get duplicate messages:


Why we need 1 hour for cooling after 3 consecutive attempts for starting the APU?

That is typical of any electrically started component.  During qualification testing of the APU, tests will be done to measure the heat build-up in the starter motor to determine how many start attempts it takes to get the motor's temperature to a critical level.  Other tests determine how long it takes to cool down enough to operate again, after it gets to that temperature.
In a nutshell, the limits are to protect the APU's starter/generator from heat damage if multiple start attempts are needed. Turboprop engines with battery powered starter/generators will have similar limitations.
Jet engines typically use bleed air driven turbine drive starters to start, and may have similar, if somewhat looser, limitations compared to an electrically started engine (to control the starter's gearbox oil temperature).
For example, on the CF34, you're allowed to crank for 90 seconds, and then there's a 10 second cool down after the 1st two attempts, and a 5 minute cool down after each subsequent attempt, up to 5 tries (after that, it's expected that you've given up and called for maintenance).  Other than that, no limitations.


Are there any "captains-only" airports in the U.S.?

As already mentioned in the comments, I don't think there is such a thing as "captains-only" airports. The airline/operator might impose special requirements on crew, such as a certain amount of experience and/or being a captain. It might also require the crew to be additionally trained for that specific airport (this can for instance be conducted during the Operators Proficiency Check).

To add to that, I could be captian on one flight, and be first-officer on the next. Makes no sense to not allow me to conduct the approach/departure, just because my rank is not captain on that specific flight.

In Europe, I know of some airports in the Alps (and Cannes on the French coast, just to name one) that require a yearly theoretical test to be made by pilots operating on the airport. This is due to some very specific rules at those airports.


Do modern aircraft have the functionality for the pilots to look behind the aircraft?

Some do, some don't.

It depends by the type of the aircraft and by the need to see behind the aircraft itself.

Just as an example, this is a render of a Boeing F/A-18E "Super-Hornet" cockpit:

On the canopy's frame are located three adjustable mirrors (like the one on the windshield of a car) the pilot can use to see what's happening behind him.

As already stated in comments, aircraft usually don't "power-back" and there is no overtaking like in cars (where cars from behind can overtake you just from left or right), so usually there is no need of mirrors inside a cockpit.

In a military aircraft, mirrors increase your situational awareness, but

with a wide Field-of-View (FoV), details or a distant aircraft or missile cannot be seen
with a narrow FoV, a smaller portion of the sky is visible

Just for reference, the F-16 or the F-22, both featuring a single piece canopy, don't have rear view mirrors. The pilot must turn the head as much as he/she can and look behind.


How should I log total hours flown in different countries?

Is it mandatory to bring your flying hours from the European logbook to the "AMOUNT FORWARD" section in the American logbook?

No, it is not mandatory to bring your flying hours from the European logbook to the "AMOUNT FORWARD" section in the American logbook.

In the USA, logging time is not required at all other than information for required recent experience and check ride prerequisites.  Also, there is no reason the EASA logbook is not an acceptable document for that purpose so long as it contains the needed information such as landings.

What is a good practice if you have multiple foreign logbooks?

Consolidate them into one logbook that best fits the system in which you do most of your flying and keep only specific additional requirements for the other systems logged elsewhere.

If you need to keep the total flight hours separate, I would use one of the customizable columns that I have seen in most logbooks and label it with whichever system you fly in less.  Then you can simply subtract that column from your grand total to deduce the other system's total time.

Although, based on how much I get picked on by my German friends for not using the metric system, I could understand the assumption that we must be different.


How would exhaust heat recovery into the combustion chamber affect the efficiency of a jet engine?

Extracting heat from the exhaust will cool and compress it, slowing it down and reducing thrust. Recirculating the heat back into or downstream of combustion will raise the temperature at that point and on downstream to the extraction point. The inevitable thermodynamic losses mean that the returned heat does not quite compensate for the heat drawn out and overall efficiency will fall a little.

What does improve efficiency is to draw through additional air mass in order to increase the exhaust mass flow, even at the expense of lower overall velocity and temperature. This is what the bypass turbofan does.

A more radical modification is to swap the combustion chamber for a heat exchanger and heat the gas via hot fluid from an external source; the hotter the fluid the better. I have seen this proposed for the hydrogen turbopump in some versions at least of the SABRE air-breathing rocket engine. It was also proposed for nuclear-powered bombers in the 1950s, though I cannot recall if those included turbojets as well as ramjets.


How does the aspect ratio of a wing impact its lift?

"The wing lift formula shows that lift of a wing is proportional to its area".

That's absolutely true. However a wing generates both lift and drag. Drag is of two natures: Parasitic drag and lift-induced drag. The sum of all drag is the total drag:

Source: Wikipedia

Induced drag decreases with speed, and has its origin in wing tip vortices. Vortices actually increase the velocity of the downwash, and changes the effective angle of attack. Which in turn changes the direction of the aerodynamic force, creating a force opposing to the direction of flight:

Induced drag, source: Wikipedia

Induced drag being due to tip vortices, if we can make vortices less efficient, then we also reduce induced drag. The way to do that is to have long wings, so the the downwash from the vortices affects only a part of the wing:

Tip vortices, source: Wikipedia

Research demonstrated that the induced drag is dependent on the wing aspect ratio, not only on the wing span. This can be understood easily: The quantity of air in a tip vortex is larger when the chord is large.

So the answer to your question is: Yes lift is proportional to the wing area, but the lift/drag ratio is proportional to the wing aspect ratio. That's why longer wings are preferred, they minimize energy lost in fighting drag.

"Why are most conventional wings shaped the same (swept back rectangles)?"

Longer wings are better for fuel efficiency, but we have other problems in the designer queue, and some can be solved by selecting the wing planform, e.g.:

We want to prevent the stall to be abrupt (at the expense of creating less lift though):

We want to delay the creation of a local supersonic flow in supercritical wings used in commercial airliners. When flying at M 0.8, airflow is accelerated to produce lift, some areas of the wing reach supersonic speed (Mach > 1). The associated shock wave creates an additional drag. By sweeping the wing we add a spanwise component to the airflow which decreases the chordwise velocity, so the shock wave appears only to a higher aircraft airspeed:

On the other hand, the sweptback wing tends to stall at the tip first, which is not good at all, as when a stall appears we need ailerons to prevent it from worsening, and ailerons are located at the tips to increase their effectiveness. So swept wings are also twisted so that the tip angle of attack is smaller than the root one, forcing the stall to start at wing root.

Wings planforms are multiple, each type of wing, or sometimes subcomponent, can improve a particular issue (possibly creating another that will be less important for the designer). See this very interesting article on Wikipedia: Wing configuration


What is the difference between EFAS and FSS?

EFAS - Inflight Weather Advisory Services (aka Flight Watch) is a special frequency in the United States on 122.0.  It uses remote communication outlets (RCO) and is typically collocated with navigational equipment.

When you talk with a FSS weather briefer on EFAS you are talking with a more experience weather briefer who can provide a greater degree of accuracy with changing weather conditions.  When I took a tour or the Prescott FSS station after Lockheed Martin took over, the tour guide state the EFAS station is manned by a Level 2 weather briefer who is more knowledgeable than a Level 1 briefer who you might talk too over a regular FSS frequency.

FSS personnel can talk to pilots over RCO and the frequency is typically found along the top of the VOR dialog box on sectional charts as well as 122.2 and 122.4.  These briefers are available to open and close flight plans, accept PIREPs and provide basic weather services.

The picture below shows that you can talk with McAlester FSS on 122.1 and receive their response over the VOR 115.2.


Which aircraft are required to have a black box?

Cockpit Voice Recorders
Required for:

large 4-engined turbine-powered planes
large 4-engined pressurized planes
multiengined turbine-powered planes seating 10+ passengers
multiengined turbine-powered rotorcraft seating 20+ passengers
multiengined turbine-powered planes and rotorcraft seating 6+ passengers and requiring two pilots

Relevant regulations: 14 CFR 121.359, 14 CFR 125.227, 14 CFR 135.151

121.359(d) No person may operate a multiengine, turbine-powered airplane having a passenger seat configuration of 10-19 seats unless it is equipped with an approved cockpit voice recorder
125.227(a) No certificate holder may operate a large turbine engine powered airplane or a large pressurized airplane with four reciprocating engines unless an approved cockpit voice recorder is installed in that airplane and is operated continuously from the start of the use of the checklist (before starting engines for the purpose of flight) to completion of the final checklist at the termination of the flight.
135.151(a) No person may operate a multiengine, turbine-powered airplane or rotorcraft having a passenger seating configuration of six or more and for which two pilots are required by certification or operating rules unless it is equipped with an approved cockpit voice recorder
135.151(b) No person may operate a multiengine, turbine-powered airplane or rotorcraft having a passenger seating configuration of 20 or more seats unless it is equipped with an approved cockpit voice recorder

Flight Data Recorders
Required for:

Multiengine turbine-powered airplanes or rotorcraft seating 10+ passengers
Multiengine turbine-powered airplanes or rotorcraft seating 6+ passengers and requiring two pilots
Large airplanes meant for use either over 25,000 feet
Large turbine-powered airplanes
Turbine-powered transport category planes

Relevant regulations: 14 CFR 91.609, 14 CFR 121.343, 14 CFR 121.344,
14 CFR 135.152

91.609(c)(1) No person may operate a U.S. civil registered, multiengine, turbine-powered airplane or rotorcraft having a passenger seating configuration, excluding any pilot seats of 10 or more that has been manufactured after October 11, 1991, unless it is equipped with one or more approved flight recorders that utilize a digital method of recording and storing data and a method of readily retrieving that data from the storage medium, that are capable of recording the data specified in appendix E to this part, for an airplane, or appendix F to this part, for a rotorcraft, of this part within the range, accuracy, and recording interval specified, and that are capable of retaining no less than 8 hours of aircraft operation.
91.609(e) Unless otherwise authorized by the Administrator, after October 11, 1991, no person may operate a U.S. civil registered multiengine, turbine-powered airplane or rotorcraft having a passenger seating configuration of six passengers or more and for which two pilots are required by type certification or operating rule unless it is equipped with an approved cockpit voice recorder that: (1) Is installed in compliance with § 23.1457(a)(1) and (2), (b), (c), (d)(1)(i), (2) and (3), (e), (f), and (g); § 25.1457(a)(1) and (2), (b), (c), (d)(1)(i), (2) and (3), (e), (f), and (g); § 27.1457(a)(1) and (2), (b), (c), (d)(1)(i), (2) and (3), (e), (f), and (g); or § 29.1457(a)(1) and (2), (b), (c), (d)(1)(i), (2) and (3), (e), (f), and (g) of this chapter, as applicable; and (2) Is operated continuously from the use of the checklist before the flight to completion of the final checklist at the end of the flight.
121.343(b) No person may operate a large airplane type certificated up to and including September 30, 1969, for operations above 25,000 feet altitude, or a turbine-engine powered airplane certificated before the same date, unless it is equipped before May 26, 1989 with one or more approved flight recorders that utilize a digital method of recording and storing data and a method of readily retrieving that data from the storage medium.
121.344(a) Except as provided in paragraph (l) of this section, no person may operate under this part a turbine-engine-powered transport category airplane unless it is equipped with one or more approved flight recorders that use a digital method of recording and storing data and a method of readily retrieving that data from the storage medium.

Exceptions: For aircraft manufactured before August 18, 1997, the following aircraft types need not comply with this section: Bell 212, Bell 214ST, Bell 412, Bell 412SP, Boeing Chinook (BV-234), Boeing/Kawasaki Vertol 107 (BV/KV-107-II), deHavilland DHC-6, Eurocopter Puma 330J, Sikorsky 58, Sikorsky 61N, Sikorsky 76A. [src: 14 CFR 135.152(k)]
Additionally, the NBAA has links to summaries, but I do not have an account with them and was unable to retrieve the data.


How does the Airbus flight computer's voting system work?

As far as I read in various documents about A320 and remember them correctly:

There are three systems handling different parts of the primary flight control:

ELAC (elevator & aileron computer) controls pitch with elevators+trim and roll with ailerons.
SEC (spoiler & elevator computer) controls roll with spoilers and if ELACs fail, pitch with elevators+trim.
FAC (flight augmentation computer) implements yaw damper. Its command is added to the rudder command. In A320 rudder pedals have direct mechanical (hydraulic) link.

The ELAC and FAC are composed of two identical units each, the SEC of three identical units (but only two of the units are used as backup for ELAC).

Each unit is composed of two dissimilar computer boards. One used i386 CPU, the other m86k CPU and each has independently developed software (to minimize risk of the same software bug in both).

One of the boards in each pair calculates the output and the other one verifies it. If the verification fails, that unit declares fault and disconnects. This is the primary way of detecting faults.

I found no reference to comparing outputs of the identical units. Except for spoiler control there are only two output and the check board is more reliable way of detecting faults anyway.

If the FAC fails, the aircraft won't maintain coordinated flight well and will tend to dutch roll, but pilots can compensate it with rudder input.

If the SEC fails, the ELAC can handle control alone. Just spoilers won't be available.

If the ELAC fails, the SEC can take over too. Turning with spoilers may cause some more drag, but not a big problem.

If both ELAC and SEC fail, the pitch trim wheels have direct mechanical (hydraulic) link and roll can be controlled by rudder by taking advantage of the yaw stability. I don't think it was ever needed in practice. Note, that is for A320 family; which controls are available in case of failure of all flight computers is different in each Airbus type.

As for data input, there are three ADIRUs (air data and inertial reference unit) and each flight computer takes input from all three and compares them. It needs two matching (similar within some limit) values to consider it trustworthy. If either more than one unit fails or no two agree, the flight computers degrade to alternate law or direct law.

In alternate law, the system stops providing alpha protection (stall), overspeed protection and, depending on what failed, other flight envelope protection (there are two kinds, with different protections lost).

In direct law it reverts to directly mapping the stick position to control surface position similar to mechanical controls. But most faults only result in alternate law except if all inertial references were lost (that would be very difficult to handle as it would mean unreliable attitude indicators too, but I don't think that ever happened either; the inertial systems are very reliable).

Alternate or direct law can also be entered if some control surface (or its actuator) fails and somewhere in the computer failure sequence, but I don't remember the exact condition (FACs calculate the limits, so if FACs fail, it will certainly degrade).


Is flow attached at fixed propeller blade at every RPM / speed conditions?

No, flow separation far away from the intended operating point is common.
Witness racing planes. Before Ratier made the first useable variable-pitch propellers in 1932, high speed aircraft had abysmally low propeller efficiencies at low speed, so much that world records were set with floatplanes (which had virtually unlimited "airfields" at their disposal). Same with small racing boats: To get over the hump (transition from buoyancy to planing), drivers need to lean forward and to patiently gain speed with their high-pitch propellers providing only marginal thrust due to flow separation.
The rotating movement of propeller blades helps to accelerate the boundary layer outwards, so flow separation on propellers happens much later (at more adverse pressure gradients) than on wings. Regardless, if blade angle and flow direction at the blade don't match well enough, separation is unavoidable.


Can I do an instrument rating checkride in an experimental aircraft?

Yes, but only if the examiner agrees. 61.45 says:

  (a) General. Except as provided in paragraph (a)(2) of this section or
  when permitted to accomplish the entire flight increment of the
  practical test in a flight simulator or a flight training device, an
  applicant for a certificate or rating issued under this part must
  furnish:

  (1) An aircraft of U.S. registry for each required test that—

  [...]

  (ii) Has a standard airworthiness certificate or special airworthiness
  certificate in the limited, primary, or light-sport category.

  (2) At the discretion of the examiner who administers the practical
  test, the applicant may furnish—

  (i) An aircraft that has an airworthiness certificate other than a
  standard airworthiness certificate or special airworthiness
  certificate in the limited, primary, or light-sport category, but that
  otherwise meets the requirements of paragraph (a)(1) of this section;

This article describes an IR checkride in a Van's RV6.


Are modern airliner avionics spill-proof?

The actual avionics are down below. The units on the center console are just control heads mostly, although they are still boxes with electronics in them.
In new design these days, there is some effort on the design side to make the units coffee resistant, by using sealed switches and rotary control devices, etc.  But they aren't completely water tight.
The components on the lower center console live a difficult life, getting splashed and kicked regularly by coffee spills and people climbing in and out. On smaller cockpits the sub panels near the bottom of the center console close to the seat get replaced quite a lot from getting kicked.
I participated in a project to approve a new switch design in an audio control panel on the CRJ900, which was right in the coffee target zone, and the switch had to be a water resistant design.
Avionics down below, if they are under the passenger cabin, can also get wet from spills in the cabin that migrate down under the floor.  On the CRJ program, certain black boxes had little rain shields incorporated above them to protect the boxes from getting dripped on.  This is expecially bad for components under the floor near entry and service doors where rain can get in and find its way under the floor and run along floor rails to drip some distance from the original source.


What licenses and/or training should one obtain to be able to fly a drone in California?

From the second link you posted:

  Until regulations establish who can fly a drone and where, Huerta said, the FAA will license drone operators on a case-by-case basis.

It's doubtful that getting an airplane or helicopter pilot certificate will aid legally with the transition. It could obviously help with the concepts, but until the FAA releases an NPRM (Notice of Proposed Rule Making), the best we can do is guess.


"Cancel altitude restriction." Under ICAO rules, does it cancel all altitude restrictions on a SID or STAR chart?

'CANCEL LEVEL RESTRICTION(S)' cancels all the vertical restrictions above and below the new assigned level. From ICAO Doc 4444 16th edition (2016):

6.3.2.4 CLEARANCES ON A SID
CLIMB UNRESTRICTED TO (level) or CLIMB TO (level), CANCEL LEVEL AND SPEED RESTRICTION(S):
i) climb to the cleared level; published level restrictions are cancelled;
ii) follow the lateral profile of the SID; and
iii) published speed restrictions and ATC-issued speed control instructions are cancelled.

The same is true for clearances on a STAR (6.5.2.4).
The proper way to cancel specific restriction(s) and leave the rest is to specify the affected point(s).

CLIMB VIA SID TO (level), CANCEL LEVEL RESTRICTION(S) AT (point(s)):

A shortcut within the SID does not cancel the restrictions after the shortcut waypoint:

6.3.2.4.4 When a departing aircraft is cleared to proceed direct to a published waypoint on the SID, the speed and level restrictions associated with the bypassed waypoints are cancelled. All remaining published speed and level restrictions shall remain applicable.


Can someone identify the Make and Model of airplane that this fuselage belonged to?

That looks like the remains of a De Havilland DHC-3 Otter
It used to wear the registration VP-FAK.

British Antarctic Survey (BAS) and the de Havilland Aircraft Heritage Centre at Salisbury Hall, London Colney have agreed on a long term loan for BAS DHC-3 Otter VP-FAK.  This historic artefact was recovered from Deception Island, Antarctica in April 2004 where it had lain for nearly 40 years since the aircraft was grounded due to structural problems.
De Havilland Canada Otter VP-FAK c/n 294 made its maiden flight in
Canada on 17 October, 1959.  It was shipped to Deception Island
arriving on 26 January 1960 before assembly and flying on 3 February.
The aircraft was flown by aircrew seconded from the RAF to BAS when it
carried the identity 294 with RAF roundels.  Flying conditions in the
Antarctic are very demanding and the aircraft was damaged a number of
times, the last time at Adelaide, making its last flight from there to
Deception Island on 7 March 1967.  Following an inspection it was
grounded due to structural problems, having flown 981.30 hours and
made 853 landings.  The aircraft was stored outside at Deception
Island in a dismantled state until recovery to Rothera ready for
shipping to Britain, where it arrived at Grimsby on 8 May 2005.

More information here


Why don't both black boxes hold the same data?

Black Box(s) is a misnomer, you have correctly mentioned their actual names.

  Why are the two black boxes holding separate data?

They have different purposes.

Flight data recorder: This is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters.

Cockpit voice recorder: This device is used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents.

  Why don't black boxes hold copies of both the FDR and the CVR data for
  extra redundancy?

Since they record different data, they are different. They are built different.

Differences:

FDR

Time recorded: 25 hour continuous
Number of parameters: 5 - 300+

CVR

Time recorded: 30 min continuous, 2 hours for solid state digital units
Number of channels: 4

Similarities:

Impact tolerance: 3400 Gs /6.5ms
Fire resistance: 1100 deg C /30 min
Water pressure resistance: submerged 20,000 ft
Underwater locator beacon: 37.5 KHz
Battery: 6yr shelf life, 30 day operation
Both recorders are installed in the most crash survivable part of the aircraft, usually the tail section.
Each recorder is equipped with an Underwater Locator Beacon (ULB) or pinger to assist in locating in the event of an over water accident.

  Are there any technical reasons for why this isn't possible or hasn't
  been attempted yet?

It has certainly been attempted.

  Is there any benefit of having the CVR and FDR in separate boxes?

Probably the reason is that different teams investigate the data obtained from them as they have to recreate the scenario before the accident.

Regulatory Details

CVR: Due to the highly sensitive nature of the verbal communications inside the cockpit, Congress has required that the Safety Board not release any part of a CVR tape recording. Because of this sensitivity, a high degree of security is provided for the CVR tape and its transcript. The content and timing of release of the written transcript are strictly regulated.

FDR: Newly manufactured aircraft must monitor at least twenty eight important parameters such as time, altitude, airspeed, heading, and aircraft attitude. In addition, some FDRs can record the status of more than 300 other in-flight characteristics that can aid in the investigation. The items monitored can be anything from flap position to auto-pilot mode or even smoke alarms.


What is the function of Boeing C-17 Globemaster III in Indian military?

The C-17 serves the same purpose in the Indian military as it does in other armed forces: it provides large-scale airlift.

India is a large country that has long borders with unfriendly neighbors, so it has a requirement to move troops and supplies quickly to any hotspots.

  "The Indian military needs to do three things: augment its ability to quickly lift larger numbers of troops as it views possible threats on its border with China; strengthen its presence on the Pakistani border; and fight terrorism and low-intensity warfare", said a senior Defence Ministry official. "India needs to triple its lift capacity", said the official.

India spent on the order of $5B buying these aircraft, it's unlikely they'd pay that much for aircraft they don't need.


Why isn't the point you begin descent part of the flight plan?

Because the Top of Descent (TOD) is calculated in flight based on current weather data, STAR/Transition assigned, directs received during the cruise portion of the flight, vectors received taking you off your planned route, etc.. The FMC does the calculation for you with higher precision in flight.

For regular ops, ATC can use the rule of thumb 10.000ft / 30 NM to calculate an estimated TOD. In most cases, they will not need to do that however, as they can give instructions to aircraft to plan a certain STAR entry gate at an assigned flightlevel/altitude.

R: DLH123, when ready descend FL240 to be level\to reach at ARPEG

During lost comms, you are expected to maintain your filed or last assigned flightlevel/altitude until you reach the clearance limit. From there you will begin your lost comms procedures which usually include holding at the Initial Approach Fix (IAF), descending at the IAF to the approach altitude, and commending the standard approach procedure for the active runway.


What is the aerodynamic motivation behind vortex generators?

You are correct that vortex generators create drag, so a successful installation depends on reducing some other drag even more. Airflow separation causes significant drag that vortex generators can reduce. The energy consumed by vortex generators making drag is injected into the boundary layer, delaying airflow separation and the eventual stall, which might be of even more value. Correcting poor flight characteristics on an existing design is often where they are used. The illustration of a wing stalling is easy to understand but may not be the best use of VGs since few wings fly continuously on the brink of separation.


How do friendly stealth planes locate each other?

The accounts that have been published of F-117 missions indicate that they generally flew single-ship, rather than formation missions, and it seems probable that B-2 aircraft do likewise.  So in a sense, the important question for those aircraft isn't "how do I know where (another stealth aircraft operating nearby) IS," but "how do I ensure that we don't collide with each other," and that's a much easier question.

There are several ways to "deconflict" multiple aircraft operating in relatively close proximity that don't involve seeing or painting each other on radar.  One aircraft operates at one altitude, another operates at a different altitude is one method, while timing over a point (you get to waypoint ABC no later than 19:00:00, and I'll be there no sooner than 19:00:30) is another, and physical separation (you stay west of this longitude line, I stay east) is another.  In practice, all of these can be combined to ensure that "your" mission is deconflicted from "my" mission.

Of note, it isn't only stealth aircraft that will use tactics like this.  Helicopters operating blacked out at night don't have air-to-air radar, and even with NVG's, the ability to see each other isn't reliable enough to plan on "see and avoid" and the "big sky theory" to preclude a mid-air, so they'll use some fairly detailed deconfliction plans incorporating separation in space and time.

More recent stealth aircraft such as the F-22 and F-35 are reported to have datalink capabilities so that they can "see" each other without radar, by means of an encrypted, stealthy broadcast of each aircraft's position and track.  This would allow multiple aircraft to fly in formation (not close formation, but perhaps 1000' or more apart), and to work with other aircraft equipped with the same datalink, so even though the bad guys would only be able to see the non-stealth aircraft on radar, the friendlies could all see each other.


There is no international blacklist of unsafe airlines. An airline can only exist if at least one country believes it is safe. Those regional blacklists are about the best you'll get.

In a formal sense, calling an airline "safe" is generally avoided. A regulator would use a term like "meets safety standards". This might be a small distinction but it helps make it clear that no airline flight is guaranteed to be safe. So the closest legal definition of a safe airline is one that has been certified as meeting safety standards by an ICAO compliant country. However this is not that helpful as different countries have different standards, as proven by the EU and FAA blacklists.

So to get an international comparison for airline safety you need to look at informal sources, which is subject to opinion. But this opinion can be formed by combining multiple official sources. A good example of how this can be done is on https://www.airlineratings.com/safety-rating-criteria/. This criteria is informal and doesn't consider the the most important behind the scenes information, but it is probably the best safety indicator we have.


As that beautiful (but rather heavy) Andean condor, Vultur gryphus, is showing, this is the go to wing for maximum lift at the slowest possible airspeed.  Not quite as efficient as the high aspect albatross, but much slower.  These wings are all about combining slightly less efficient bottom lift with more efficient (air bending) top lift.  Perfect for catching thermals and riding them to higher altitudes.
The major con is they are so good at making lift that an increase in airspeed can create surplus lift.  Lowering AOA then creates major turbulence underneath the wing, as you surmised.  Now imagine bringing the leading and trailing edges up, making a thin flat wing.
This is exactly what airliners do when they want to go 3x faster.  Condors need not worry about this.
Thin wings also lack structural strength.  This becomes a major issue with scale.  Early air craft replaced these wings with solid thick wings as size and speed increased, but camber remains a valuable tool today to help slow an approaching aircraft to a safe landing speed.


Is the arrival segment of an IAP in PANS-OPS the equivalent of FAA's feeder route?

An arrival segment can be part of both an arrival route and a designated STAR. Both are protected with the same design criteria.

The STAR chart consist of designated routes linking the approach procedure with ATS-routes or exit points in Free Route Airspace (FRA). An arrival route is simply a collection of arrival segments which are not part of a STAR when it is not operationally necessary to publish the route using the STAR criteria in ICAO DOC 8168 Vol. II Part I, Section 4, Chapter 2. The non-STAR arrival routes are published on the Instrument Approach Chart (IAC) as part of the Instrument Approach Procedure (IAP).

Here is an example from the Norwegian AIP:

The dotted lines from AND, SJA, FS and EVD to the IAFs are arrival routes containing arrival segments. These are the eqvivalent to feeder routes in TERPS, as they are defined equally.


This is called a "strake" or "chine" (Aerodynamic fan cowl strake/chine, Nacelle strake/chine).
They allow the aircraft to generate more lift at lower speeds, which entails such positive consequences as lower stall speeds, lower landing speeds, lower take-off speeds and shorter runways.

Strakes should be used if the nacelles are mounted closely under the wing of the aircraft, see also Why don't all aircraft use/need nacelle chines?. Nacelles are usually mounted like that in order to

maximize the distance between the lower nacelle side and the runway, so that the engine/fan cowl/nacelle doesn't hit the ground during violent landings when the wings bend down, and in order to
minimize the risk for runway debris being sucked into the engine.
Source: Flugzeugtriebwerke, Bräunling Willy J.G., VDI-Buch, Springer Vieweg, 2015

From US Patent 20100176249: Engine Nacelle Of An Aircraft Comprising A Vortex Generator Arrangement:

  With an optimal arrangement and at high angles of attack, such vortex generators, which are known as nacelle strakes or chines, generate a powerful vortex that flows over the wing, where on a slat in front of said wing it delays airflow separation until the aircraft flies at greater angles of attack.

The idea dates back to 1971 (US Patent 3744745: Liftvanes):

  in operational conditions wherein high angles of attack are encountered, such as in landing or takeoff, the vanes oppose the strong upwash around the nacelle, reducing the flow separation on its upper areas, and providing a strong downwash marked by marginal trailing vortices

From R.S. Shevell. Aerodynamic Bugs: Can CFD spray them away? 1985

  DC-10 wind tunnel tests showed a significant loss in maximum lift
  coefficient in the flap deflected configurations, with landing slat
  extension, compared to predictions. This resulted in a stall speed
  increase of about 5 knots in the approach configuration. The initial
  wing stall occured behind the nacelles and forward of the inboard
  ailerons. The problem was traced by flow visualization techniques to the
  effects of the nacelle wake at high angles of attack and the absence of
  the slat in the vicinity of the nacelle pylons. The solution was
  developed in the NASA Ames Research Center 12 ft. pressurized tunnel and
  turned out to be a pair of strakes mounted forward on each side of the
  nacelles in planes about 45 degrees above the horizontal. The final
  strake shape was optimized in flight tests. The strakes are simply
  large vortex generators. The vortices mix the nacelle boundary layer air
  with the free stream and reduce the momentum loss in the wake. The
  vortices then pass just over the upper surface of the wing, continuing
  this mixing process. The counterrotating vortices also create a downwash
  over the wing region unprotected by the slat, further reducing the
  premature stall. The effect of the strakes is to reduce the required
  takeoff and landing field lengths by about 6%, a very large effect.


The short answer is that the final qualification tests are done against drones like the QF-4, which are converted from retired F-4 fighters.  These tests are still extremely expensive, into the millions per aircraft destroyed, so there are many dry runs and non-destructive tests completed beforehand.  Sacrificing a target drone isn't done until the project team is very confident of a positive result or they are unable to obtain necessary data by other means.


Is there a specific purpose for the silver "swoosh" on Air Force One?

It's just for looks; an area of unpainted aluminum, polished.
In this close up you can make out the rivet lines and skin laps of the bare aluminum surface.  With a little work it's easy to get a finish like chrome plate, especially on a queen of the sky like that.

Back during American's natural finish paint scheme days, 80% of the fuselage was unpainted and polished.  AF1 just does it on a little patch so it's like a chrome accent.
There was significant weight saving in AA's case, but they finally gave in and painted their entire airplanes because the polishing has to be done regularly and is a pain, and over time the polishing, on an airplane that spends a lot of time outside and constantly re-oxidizes, slowly removes the pure aluminum cladding of the metal that is its corrosion protection.
Vinyl wrap is now starting to become common on airliners, and in theory you could probably do that sort of accent today with "chrome look" vinyl wrap, but AF1 has had that paint job for decades.


Why is the King Air avionics switching system wired normally closed?

Design elements like this generally have to do with failure modes and how you want the system to fail when (not if) it fails. In this case, if there was a momentary or worse, permanent, loss of DC power to the relay or it failed for another reason you would want them to stay closed (and continue in the "ON") position so you would not lose your avionics (provided the power supply was some how still operational to them). Unlike most other electric components (semiconductors) relays are actually electro-mechanical components and they do have moving parts with in them that can fail. In my experience (non avionics mostly) relays have a much lower cycle lifetime than their semiconductor friends.

If we dive even a bit deeper into them, a relay is effectively an electromagnet coil that actuates a small metal rod that generally moves a copper (or similar) strip to close a switch connect. Applying a steady state voltage to a coil to generate a magnetic field (and keep the relay in a desired position) also drives current through the coil. The coils, being very thin gauge heat, act like resistors and can generate a substantial amount of heat. Due to the very thin gauge of the wire this can lead to melting and shorting of the coil. The wire also tends to be resin coated which can heat and melt as well causing a short. In turn you are correct that they don't want to he help on for a long period of time.

This is the electrical equivalent of many mechanically similar ideas in aircraft design. For example some landing gear in planes is held up using positive pressure so should the pumps fail the landing gear may simply deploy or be able to be shaken down by releasing a lock, the idea being its better it can come down in the case of a system failure than be stuck up.


What's this sound? - Dogfight between F14 & MiG23

That is the aural conversion of the input of an AIM-9 missile's infrared seeker head.  The missile allows the shooter to operate it in either a caged mode, that is where the seeker head is slaved to the angle and azimuth of the radar antenna, or uncaged mode, where the seeker head can freely seek out and track a bright infrared source like a jet engine on a fighter.

When the AIM-9 missile made its debut, the aural lock on cues were the only means a pilot had to know that the missile had acquired the target.  Today, pilots can often select this engagement mode if they wish to keep their fire control radars off in order to avoid detection.  When the missile seeker head is searching for a target, it makes a mechanical, raspy growling sound.  Once the seeker head acquires a heat source, the tempo of this growl picks up in conjunction with a steady mid to high-pitch tone.  You will often hear pilots acquiring a lock on an enemy aircraft refer to it as "getting a tone"; this is what they are talking about.


What does automatic pitch trim is available mean, when bank angle is below 33°?

In the context of the A320 as you are describing, pitch trim does not mean trimming with the horizontal stabilizer. Instead, it means that up to 33 deg bank angle, no aft stick pressure is needed to maintain horizontal flight, or more precisely, the load factor (for example, at 33 deg bank, the load factor is approximately 1.15g).

Up to 33 deg bank, the Normal Mode automatically commands the necessary load factor with the longitudinal side stick neutral. Since Normal Mode also ensures a neutral spiral stability up to 33 deg bank outside of High Speed Protection, you can maintain a coordinated level turn with side stick completely neutral.

Beyond 33 deg, longitudinal stick neutral no longer commands the necessary load factor for horizontal flight. Therefore, you would need to have aft pressure. Furthermore, there is positive spiral stability, which means non-zero lateral pressure is also required to maintain the bank angle.

For more information, you could consult: source 1 and source 2.


What causes pressure disturbances ahead of the wing?

An approaching body needs to push air out of the way. Directly ahead of it, it will compress the air such that the local pressure increase will push the air out of the way. When the body is a lift-producing wing, the lower pressure on the upper side will suck the air towards it. So what can be observed are two effects:

Air gets compressed ahead of any body approaching at subsonic speed, the more the faster the body moves, and
When lift is created, this pattern will be distorted such that the flow will turn in the direction of the lift-producing suction.

The propagation speed of small pressure changes can be observed with your ears. Sound is just that: Small fluctuations in pressure. An approaching wing is just like an approaching siren, only that the siren emits an oscillating pressure variation and the wing an aperiodic one.

For the video my recommendation is

Note how the flow lines diverge ahead of the airfoil: This is where the flow is slowed down. At higher angles of attack you will also see how the flow lines bend up ahead of the approaching airfoil.


Why is the total count of people on a plane given as the number of 'souls' on board?

The primary reason is probably that it ensures there is no confusion between passengers, crew, or infants. Technically, "passengers" is the number of seats occupied, "crew" is both the pilots and flight attendants on duty. So any small children brought on as "lap children" will not be included in the "passengers" count, but should be included in the total number of people on board.

I found another interesting point over on the English Stack Exchange site, which is that dead bodies are sometimes transported as well. In this case, some might consider these "people" as well. Also, in an incident, the bodies should not be confused with the regular passengers.

So, "souls" effectively communicates the number of living humans on board.

There may certainly be holdovers from the maritime influences on aviation as well.


How come sonic booms only occur once at the speed of sound and not multiple times?

Your question is:

  Why is it that the sonic boom only occurs at the moment the plane crosses Mach 1?

The answer is: It doesn't. Sonic boom first occurs when the plane crosses Mach 1 and the plane continues producing sonic boom as long as the speed stays above Mach 1.

Another part of your question is:

  How come sonic booms only occur once?

And the answer is: because the plane flew over you once. If the plane were to turn around and fly over you a second time you'd hear two sonic booms.

When you hear a sonic boom it doesn't mean that that boom was generated at Mach 1. It only means that the boom was generated at speeds equal to or greater than Mach 1. For example, a plane travelling at Mach 3 would still produce a sonic boom but you'd still only hear it once because the "boom" would only reach your ear once.

To understand this you need to understand what a sonic boom is.

Various parts of the airplane generate sound. Form the roar of the jet engines to the whistle of the skin of the aircraft moving through the air.

When travelling at normal subsonic speed. These sounds travel normally through the air and what you hear is a continuous sound of an airplane flying.

When travelling at or faster than the speed of sound, all these sounds arrive at your ear simultaneously. That is to say, if normally you'd be able to hear a plane passing overhead over a period of 10 seconds (for example) then at supersonic speeds all those 10 seconds of sounds (engine roar, woosh of the wings etc.) arrive at your ear at the same moment.

Since all the sounds you'd ever hear from the airplane arrive at the same time, the result is a very loud boom (all the 10 seconds or more of sound added together).

That's why you only hear it once typically.

There are exceptions though. If the plane is long enough, and the nose and tail generate loud sounds, it is possible to experience a double sonic boom caused by the tail generating a second boom. But generally, even a very long plane like the 747 or A380 (or Concorde) would take only a very tiny fraction of a second to travel the length of their body at supersonic speeds. You'd probably need a plane a mile long to experience a proper double boom.


How does CDI scaling transition from terminal to approach sensitivity?

Beginning 2NM prior to reaching the final approach fix of an activated approach, the GPS will smoothly taper down the CDI scale from 1-NM full-scale deflection (from the center) to 0.3-NM at full-deflection over that 2-NM flight distance and reach a scale of 0.3-NM as the final approach fix is reached.
AIM Page 1-1-25

"When within 2 NM of the Final Approach Waypoint (FAWP) with the
approach mode armed, the approach mode will switch to active, which
results in RAIM and CDI changing to approach sensitivity. Beginning 2
NM prior to the FAWP, the full scale CDI sensitivity will smoothly
change from ±1 NM to ±0.3 NM at the FAWP. As sensitivity changes from
±1 NM to ±0.3 NM approaching the FAWP, with the CDI not centered, the
corresponding increase in CDI displacement may give the impression
that the aircraft is moving further away from the intended course even
though it is on an acceptable intercept heading. Referencing the
digital track displacement information (cross track error), if it is
available in the approach mode, may help the pilot remain position
oriented in this situation. Being established on the final approach
course prior to the beginning of the sensitivity change at 2 NM will
help prevent problems in interpreting the CDI display during ramp
down. Therefore, requesting or accepting vectors which will cause the
aircraft to intercept the final approach course within 2 NM of the
FAWP is not recommended."


Can multiple helicopters be used to lift a heavy load?

This video on YouTube apparently shows that it has been done at least once. A rigid beam was used to counter the forces that would draw the two helicopters together.

Screen grab:

I also found this fascinating report (.PDF link) from Piasecki (now part of Boeing Defense, Space & Security) that studied the feasibility of attaching two CH-53D helicopters to each other, including interconnected powerplants and flight controls!


What is the optimal way to climb fastest between two points on a Cessna 172N?

Ron nailed it. (See comment on OP.)
It depends on what you’re trying to achieve.
Climbing “fast” in terms of maximum vertical speed = Vy (best rate)
If the noise sensitive zone is immediately surrounding the airport, you want to use Vy to put altitude under you as quickly as possible.
Climbing “fast” in terms of maximum feet per nautical mile = Vx (best angle)
If the noise sensitive area is a few miles away, you may want to use Vx to get to altitude before overflying the zone.
I gather from the question that the noise sensitive area is right next to the airport.  If that’s the case then Vy is likely your best option.
While accelerating to 100 and then pulling up feels satisfying, just pitching for and holding Vy (or Vx) is more effective.  Peter’s answer explains why this is.
In any case, watch your oil temps (or cylinder head temperatures if you have a CHT gauge) and prioritize keeping the engine cool over noise abatement.  While being a good neighbor is important, taking care of the engine and flying safely is even more important.


How do elevons work to roll a flying wing?

Good question! There's a bit of a misconception: when the elevon moves up, it actually decreases lift. It pushes air up which pushes the wing down.

This explains the roll behaviour, but how does decreasing the lift make the plane go up? The key here is that the lift is reduced only at the rear of the plane. In other words, the rear of the plane is pushed down, but only the rear. This makes the nose point up (just put the plane on the floor and push down on the tail, the nose will be up).

In this new orientation, the angle of attack (the angle of the wing relative to the airflow) is increased, and consequently the lift increases (the little bit of downforce at the rear of the wing doesn't really make a big difference). The plane will start to climb, which will reduce the angle of attack (the wing will be pointed the same way as the direction of travel), until the plane is in a steady climb.


Would a helicopter with the blades on the bottom fly the same, if at all?

Yes that is possible, like the Hiller flying platform demonstrated. It had two counter-rotating propellers inside a shroud and the pilot controlled his craft by shifting his body weight, like on a Segway. There is no law of physics that prohibits a helicopter from flying upside down.

The Hiller flying platform was one of several types built in the 1950s, after it was observed that controlling an underslung rotorcraft by weight shift could be learned by untrained personnel in 20 minutes. The DeLackner Aerocycle was another platform built based on this finding. The idea was later abandoned due to practical issues like kicking up rocks into the rotor blades, and an at the time unexplainable interference between the counter-rotating blades. The Aerocycle had a fixed rotor head, the dynamics of which were poorly understood at the time.

For full scale helicopters, having the rotor underneath the helicopter has the same stabilising effect on flight characteristics. Stability of helicopters (and of fixed wing aircraft) is studied from the perspective of aerodynamics: the effects of wind gusts or control inputs.

In the hover, the speed stability ${\delta M}/{\delta{\dot{x}}}$ plays a significant role: if positive, the hover is unstable. A human can learn how to control an unstable platform if the time period of the oscillation is high enough (conventional helicopter pilot), but it is much easier to fly in an aerodynamically stable aircraft (the underslung platforms intended for general infantry personnel). The speed stability effect in the hover equates to a gust of wind blowing from directly forward, does then the change in moment tend to amplify or counteract the effects of the gust. This can be visualised like so:

Image source

The gust blowing on the helicopter tilts the rotor back, which tilts the thrust vector. A teetering conventional rotor has a positive ${\delta M}/{\delta{\dot{x}}}$: it wants to flip backwards ever stronger, and is therefore aerodynamically unstable in the hover. An underslung teetering rotor has a moment change that stabilises: it tilts the fuselage back, and due to aerodynamic coupling the rotor follows back to neutral. A rotor with hinge offset has a smaller stabilising moment, but a stronger fuselage/rotor coupling.

So to answer your original questions: Yes the helicopter with an underslung rotor would fly, and it would be easier to control than a conventional helicopter. It is just a bit unpractical, that's all.


Is the ATR empennage configuration considered a T-tail or a cruciform tail?

As far as technical specifications are concerned, some explanation is:

Excerpt from Wikipedia (formatting is mine):

  T-tail

  DESIGN: The horizontal stabilizer is mounted on top of the fin,
  creating a "T" shape when viewed from the front.

  PURPOSE:

  T-tails keep the stabilizers out of the engine wake, and give better pitch control.
  T-tails have a good glide ratio, and are more efficient on low speed aircraft.
  However, T-tails are more likely to enter a deep stall, and are more difficult to recover from a spin.

  T-tails must be stronger, and therefore heavier than conventional
  tails. T-tails also have a larger radar cross section.

  Cruciform tail

  DESIGN: The horizontal stabilizers are placed midway up the vertical
  stabilizer, giving the appearance of a cross when viewed from the
  front.

  PURPOSE: Cruciform tails are often used to keep the horizontal
  stabilizers out of the engine wake, while avoiding many of the
  disadvantages of a T-tail.

In reference to your comparison between ATR 42/72 with Boeing 727, if we take out the difference in tail heights (ATR 42: 24' 11"; ATR 72: 25' 1"; B727: 34' 0"), the position of horizontal stabilizer on vertical stabilizer is almost the same on these three airplanes. So they all match closely to a T-Tail configuration rather than a cruciform.


Obtaining Captain's name on historical flights?

Generally, no.  As a matter of protecting employees' privacy, that sort of information isn't typically made available beyond what a passenger may notice (nametags) or remember from a PA ("This is Captain Smith...").

In an unusual situation, it might be possible to get a name by contacting the airline, but it's probably unlikely that you'd get an answer back unless the pilot happened to call or write back to you.  Which could happen, but not often.


How is heavy cargo secured in military cargo carriers?

The cargo in a military aircraft are secured in the cargo hold using chains, straps etc. connected to stowage tie-down devices, which go into tie-down rings . The following image shows a M1 Abrams tank secured in C-17 Globemaster III using tie-down devices.

USAF uses three different types of devices to secure cargo in aircraft, which vary in their load capacity:

MB-1 tie-down device with 10,000 lb rated capacity.
MB-2 tie-down device with 25,000 lb rated capacity.
CGU-1/B tie-down device with 5,000-pound rated capacity

The MB-1 and MB-2 are similar in their form and function, with the only difference being their load capacity.This image shows a close-up of the MB-1 and MB-2 tie-down devices:

"C-17 Globemaster III no. 5139 stowage tiedown devices" by BrokenSphere - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

The hook goes into the tie-down ring, while on the other end, straps or chains (from the cargo) go.

The CGU-1/B is a 20-foot nylon web strap with two metal hooks at both ends. While one hook is stationary, the other hook has a ratchet device and can be moved and tightens the device when it is being used.

Note: Apparently, Military designation system refers to MB-1 and MB-2 as CGU-3/E and CGU-4/E respectively.


What are the aerodynamic implications of different conditions with the same Mach number?

The Mach number only indicates the behavior of compressibility effects, but does not provide any indication about other effects like inertia and viscosity (read turbulence) or heat transfer.

For high subsonic and supersonic aerodynamics one should typically compare both the Mach number (compressibility) and the Reynolds number (turbulence).

So at the same Mach number but different densities, the Reynolds number will be very different and therefore the turbulence effects will differ highly. Only the compressibility effects will be similar (shock waves).

Note that at low subsonic speeds (Mach<0.3), the compressibility effects become negligible and one can get away by only comparing the Reynolds number.
And at hypersonic speeds (Mach~>5) more similarity parameters are needed.

More information about dimensionless numbers in fluid mechanics on Wikipedia.


How does banner tow attach and release work?

There are actually a couple of different towing mechanisms out there. You've got your traditional banner pick, with the ropes and the hooks and all that, but there's also a new type of billboard mechanism that allows a tow aircraft to take off with the billboard already attached; it unfurls as the aircraft gains altitude, and can eliminate a potential inefficiency in the process (some days are worse for banner picks than others due to high winds, turbulence, etc.), but it limits the tow aircraft to some pretty small billboards and letter banners are pretty much a no-go.

Talking about the traditional method of banner towing, there are a couple of things to cover.

The banner/billboard setup on the ground - they will be attached to a tow rope (usually about 200 feet long) with a loop at the end. This loop is strung out between two poles a small distance apart. The goal of a banner pick is to have the hook pass between the poles, thru the loop; do that and you will be able to pick the banner off the ground. The banner or billboard will be laid down upwind of the poles (with the tow rope fully extended), so that the pick takes place into the wind; the lower ground speed will help with timing and allow the banner or billboard to come off the ground more smoothly. A small windsock is a common addition next to the poles to make it easier for the pilot to spot them and to give some local wind information. The banners and billboards may be set up parallel to a runway (usually the active runway), or there may be a designated spot elsewhere on the field.
The hook itself is attached to aircraft with a tow hitch and it is possible to have multiple hitches on the same aircraft (highest number i ever saw was 4 on a Piper Pawnee); they get used sequentially i.e. drop the hook, pick up the banner, fly the banner, drop the banner, drop the next hook, pick up the next banner, fly said banner, and so on until you run out of hooks. Most of the time, hooks that are not in use will be tied down somewhere accessible to the pilot who will drop them manually. That Pawnee I mentioned earlier, however, had the hooks attached to hitches on the aircraft's belly, from where they would be released with a switch, so there's more than one way to skin a cat. The hooks are normally attached prior to engine start and the pilot needs to make sure there is no slack in the line, to avoid it becoming entangled in rudder or elevator cables (more on that later), or other assorted bits and pieces of equipment.
Banner tow procedures

Take off is normal, but depending on your hook and cockpit setup, you may have to hold the hook in your throttle hand as you're taking off (this was the case with the Husky I towed in). Be careful not to hit anything with it.
After climbing through about 50 feet AGL, side-step the runway, and drop the hook. Procedure varies depending on your setup, but we used to extend the arm holding the hook as far out the window as we could get, give a gentle tap on the rudder to kick the tail out of the way and toss the hook outwards and away from the airplane. Kicking the rudder was important due to the way the rudder control cables ran in the Husky; we had one pilot who didn't and nearly wrecked when the rope got fouled around the cables, forcing a rudder hard-over once there was tension in the line after the pick - fortunately he was a big guy and the runway was sufficiently long that he was able to overpower the rudder and make a safe landing. Tossing the hook outwards is important lest it get caught up in the propwash and bang against the skin of the aircraft. Again, this happened (wasn't me though).
Coming around for the banner pick - depending on where the banners are set up, you may end up flying almost a regular traffic pattern, but it usually happens at much lower altitudes (5-600 feet) and the banner tow waiver may require that you avoid flying over populated areas to do so, so you may end up flying, say a right-hand pattern instead of your regular left. Either way you end up doing it, you want to end up downwind of the poles, similarly, if you will, to coming in for landing.
The actual banner pick - this is where you'll see a lot of variation. Some outfits will come in flat, just above the poles and pull up once they pass them (unusual, but some do it that way), others will come in high and dive towards the poles, and pull up once past them (it's very pretty and dramatic, but not a lot of room for error IMO). We used to be a bit more sedate about it, and came in as if for a landing, with the goal of touching down at the top of the banner (i.e. the end nearest to you). Obviously, you have to correct for crosswind, which you can do by shifting your line left or right depending on wind direction; the goal is to place the hook, which is trailing behind you and getting blown about by the wind, between the poles. Either way you do it, once you pass the poles, you pitch up immediately to at least 45 degrees or so, and apply full throttle. You zoom climb to about 200 feet AGL and then reduce the pitch angle to be able to maintain a slow-speed climb. Do this right and the banner or billboard will come smoothly off the ground; you may feel a slight tug as tension is applied through the towline if you haven't been smooth enough and ended up yanking the banner off the ground. Continue to climb to whichever altitude you've planned for and, when stabilized in the climb, try to take a look behind you (if you can) to make sure you've picked successfully and that the banner didn't get damaged or something. If you can't look behind you, you can check during a turn, or have your ground crew radio/text and let you know.
Fly the banner - you want to fly slow enough to avoid stressing the engine, airframe, tow rope and banner, but not quite so slow that the engine can't get enough airflow to cool down (remember, on the backside of the power curve, power required increases the slower you try to fly). Watch your altitude and distance from people and objects (the powers that be are quite serious about it), look out for towers (especially those that come with guide cables and the like), high rise buildings, and other traffic, and try not to get too bored flying in circles for hours.
Drop the banner - when you come back in to drop the banner, the goal is to drop it low enough to the ground that the wind won't have time to blow it away onto  active runways (or into the trees - I had to help pull somebody else's banner out of the trees once, not fun). Ideally, you might want to drop it as close as you can to where the ground crew has their bags and everything setup to spare them having to haul heavy banners and billboards over long distances. You release the hook using a lever bolted onto the floor of the aircraft and then apply power, climb out, and come around for another pick or a landing, whatever the case may be.

Hope this helps, let me know if you'd like to know more about any of this.


Where to find information about aircraft type knowing the flight number and date?

FlightAware will give you all the info and has an API.


Which fighter jet is the safest outside of combat?

There are a number of barriers to labeling a single fighter as the "safest" - your proposed method is probably the best overall picture, but there are some barriers to even that.

Differences in use and training

Fighter aircraft are extremely complex and are asked to performed complex missions, even in training, where there may be little room for error. Due to the United States' huge military budget and wide-reaching foreign operations, US military pilots tend to have high flight time compared to many smaller countries, including other ones that fly US-produced aircraft. (Russia's modernization has led to increased flight time there, though still far below US or Cold War levels. China's modernization has pushed their training levels much closer to the US, as noted on p. 10 in this 2016 study ).

As pilot experience leads to decreased accident rate (to a point, at which accident rate goes up again even higher than inexperienced pilots), some of the air forces which fly very little likely have some contribution to a possible higher accident rate, irrespective of the safety of the aircraft they fly.

In addition, differences in philosophy of use from one country to another may lead to more dangerous employment - high speed low level flight is inherently more dangerous than flying high-altitude caps - and two air forces may utilize the same aircraft in such vastly different roles. This may lead to a fatal accident from a malfunction that at altitude, would be comparatively benign.

Lack of records

This is the biggest barrier, I think. Unlike commercial airliners, which worldwide predominately are produced by only two major manufacturers (Airbus/Boeing) and a handful of smaller regional-class producers, fighter aircraft are produced by a number of companies:

USA - Boeing, General Dynamics, Lockeed Martin
Sweden - Saab
Britain - BAE
Europe (multiple contributors) - Eurofighter GmbH
France - Dassault
Russia - UAC (combination of former companies Mikoyan, Sukhoi, Yakovlev, and others)
China - CAC, XAC, HAIC, Shenyang
India - HAL

While some of these aircraft are unique to a single country, many are used by multiple countries (e.g. for US-produced aircraft, numbers may be available for the US accident rates, but not for other countries). The F-16 has had 4,500+ aircraft produced, and is operated by 26 different countries on 5 continents. One difficulty with this, other than the difference in records is the number of different variants in service. As Mazura noted in a comment below, the F-35 has seen no fatal incidents in US service, but other countries have had incidents. 9 countries currently operate a F-35 variant, with at least 4 more countries planning to acquire the type. The MIG-29 has at least 24 current and 10 former operators spanning 5 continents as well. So great difficulty exists in retrieving fleet-wide numbers (in addition, as political situations change, it may make spare parts acquisition or maintenance more difficult, leading to major variances in reliability).

In addition, countries with smaller militaries that have traditionally relied on importing their military aircraft such as Japan, Israel, Turkey, Pakistan and Taiwan have produced or are developing indigenous fighters.

Due to the diverse nature of these countries that produce the aircraft - some of which are produced by somewhat state-owned companies, it makes the retrieval of records difficult.

Additionally, since Airbus and Boeing need private corporations to purchase their aircraft, and safety is a huge selling point (or rather, poor safety record is a major turn off) in selling tickets, then the easy retrieval of accident histories for airliner class aircraft is much more crucial than high-performance military aircraft.

Age of Fleets

Looking at probably the best kept public record producers,  The U.S. Air Force Safety Center has year-by-year and lifetime mishap histories for all current USAF fighters, but it doesn't separate out combat and non-combat incidents/fatalities. But when you compare the various US fighters:

A-10: 51 fatalities, 5.65 million hours (0.90/100,000 hours)
F-15: 44 fatalities, 6.80 million hours (0.65/100,000 hours)
F-16: 86 fatalities, 11.28 million hours (0.76/100,000 hours)
F-22: 1 fatality, 355 thousand hours (0.28/100,000 hours)
F-35: 0 fatalities, 96 thousand hours (0.0/100,000 hours)

But the F-22 has only been flying since FY2003, and the F-35 since FY2012, so comparing those to aging aircraft that have been around since the early 1970s doesn't paint an accurate picture. You can look at the 5-year and 10-year trends, however to see a more recent summary. For the USAF, the best rate would be the A-10, with no fatal accidents in the last 10 years, averaging 88,000 flight hours a year. Not unique to the USAF (indeed, all aviation sections of the US Military deal with this), many other countries have dealt with aging fleets as well, often due to the less frequent production of new designs since the cold war. (ex: Russia, Iran).

One note is that many combat aircraft in service with even the most modern air forces are no longer in production - the A-10 was last produced in 1984 and the MIG-31 in 1994, while some aircraft (like the MIG-29 and F-16) are still in production today.

Conclusion

Due to the barriers listed above, I think objectively calling a single fighter the "Safest" is likely an impossible task. But from the various characteristics, the safest record probably belongs to an aircraft that is flown by a country fairly regularly, leading to good experience in its pilots, possibly is employed predominately in an air-to-air role more regularly, and is produced more recently, yet long enough ago that the major design flaws in a new aircraft are worked through. I would say the best candidates would be the F-15E or the Eurofighter (which I found an article indicating 2 deaths in 240,000 flight hours across a diverse group of countries - Wikipedia indicates another 4 fatal crashes since then in an unknown amount of flight hours).


What "jet engine" is featured in this ad that Simone Giertz made for a phone?

The engine seems quite obviously to be a Boeing T50 Turboshaft Engine variant, T50-BO-8A is a very, very close match, you can see pictures and info here:
National Air and Space Museum: Boeing T50-BO-8A

All major visible features are exactly the same, some minor parts are different, but may have been switched by current and/or previous owners.

Engine concept dates back to late 40's.

I did not add a picture here because of the copyright restriction posted on the National Air and Space Museum website.


Is there a website with a list of all commercial airline incidents?

Each jurisdiction or organization will have its own reporting system, not all will provide that information to the public. News, social media, and websites provide information but more research is required to determine which parts are accurate.
https://aviation-safety.net/
The Aviation Safety Network is probably your best bet for both completeness and accuracy. The database is fairly comprehensive, contains events as far back as 1919, and lists sources. You can browse by date, location, and aircraft type. The Wikibase allows users to add incidents, providing coverage of many more small aircraft incidents but may be less accurate.
https://avherald.com/
Avherald strives for accuracy but is far from complete. Information is not reported without reasonable verification, sources are provided when possible. The team sometimes even has access to the radar data to provide more insight. Many news outlets use this as a source. Entries go as far back as 1999, but the items are intended to provide information on accidents and an overview of the types of incidents occurring worldwide. This will make any statistical analysis hard.
https://www.aeroinside.com/
AeroInside appears to just copy from Avherald and put the entries in a fancier format with ads and make them a bit more searchable.


Are Crew Resource Management (CRM) and other Human Factors methods effective?

A student of mine, who has a background in industrial engineering and is an emergency medicine physician, has morphed his career to include the application of CRM into emergency medicine and operating room procedures.  The health industry has in general been moving that way because it is saving lives and lawsuits.

Several people have published retrospective analysis of aviation accidents, which tend to contrast the kinds of errors which occurred prior to CRM, and the changes in flight deck politics.

Military team operations, firefighting and other industry segments have started incorporating CRM into their training, and with measurable result.

Much of CRM today was developed  in response to significant aircraft disasters in the 1970's coupled with research at NASA and some universities which provided more insight as to how crews work together.  As an example, the unquestioned authority of the senior captain, was a factor in an alarming number of major accidents.  That protocol has been substantially replaced with a more collaborative protocol, and there are fewer accidents involving the same aspects of flight crew dynamics.

The medical application paper referenced below probably has statistics and material you might find particularly useful in your training.

Journal Articles:
https://www.tandfonline.com/doi/abs/10.1207/s15327108ijap0104_3

A medical application reference which talks about lessons learned in aviation:
https://www.emsreference.com/printpdf/47

A scholarly critical data driven analysis:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a502230.pdf

  Technological advances continue to attempt to improve reliability and safety in
  aviation. Design considerations throughout the acquisition process must also continue to
  expound on integrating humans, including our cognitive and physiological capabilities, as
  fundamental aspects of aviation systems. Nevertheless, CRM training continues to be the
  primary method in mitigating the number of mishaps due to human crew coordination
  error in aviation. The program must go beyond simple training requirements and become
  more in grained into the culture. Perhaps the evidence found in this study suggests a
  transformation of cultural acceptance is gradually occurring.


Are carbonated drinks considered dangerous goods for air freight?

Each operator is of course entitled to apply stricter regulations, but there's no restriction against carbonated drinks in the IATA-DGR (based on the ICAO TI, which sets out the framework for dangerous goods regulations).

The maximum amount of pure CO2 an operator may transport in approved packaging (iaw. IATA-DGR) is:

In gaseous form (UN1013): 150 kg on cargo only aircraft, and 75 kg in passenger/cargo aircraft.
In liquid form (UN2187): 500 kg on cargo only aircraft, and 50 kg in passenger/cargo aircraft.
In solid form "dry ice" (UN1845): 200 kg for both cargo and passenger/cargo aircraft


Does the rudder need to be held throughout a coordinated turn?

When you deflect the ailerons, you increase lift on one side of the wing and decrease it on the other. This causes a parallel increase of the local induced drag where lift is increased and vice versa. The consequence of that is a yawing moment which needs to be corrected with rudder deflection.

Once your ailerons are neutral, this yawing moment goes away, but now your airplane is in a constant yawing motion which increases airspeed on the outer wing and swings the tail around, so your vertical tail sees some sideslip even if your ball is centered. The airspeed differential between inner and outer wing causes some friction drag differential which tries to pull the aircraft out of the yawing motion. Depending on the tendency of the rudder to follow a sideslip, you will need some pressure to keep the yawing motion going.

It is hard to be more specific, because details depend on the particular airplane.

In most of the airplanes I have flown, you also need to keep some aileron deflection to keep your bank angle constant. Here are two effects which go against each other, so again the details depend on the particular aircraft. One effect is caused by the airspeed difference which causes a lift difference between inner and outer wing. To correct this, you need to deflect the aileron against the bank. The other effect is caused by the different centrifugal forces of the masses of the inner and outer wing. The whole wing is moving at the same angular velocity, but centrifugal acceleration is the product of the square of the angular velocity and the radius of your motion. Since the outer wing flies at a larger radius than the inner wing, the masses of the wing will try to pull the aircraft level. This needs aileron deflection into the bank. If you are lucky, both effects cancel each other out, but normally they don't.


Artificial horizon - "horizon bar" or "symbolic airplane adjust"

Instrument parallax has to do with viewing position of the pilot compared to the instrument. You adjust the symbolic airplane to the horizon bar on the outside of the instrument, not the part that moves, so you don't have to wait for it to spin up or find flat ground. I do it as part of my pre-start instrument checks, after adjusting my seat.
All mechanical AIs should have an adjustment mechanism, but many modern ones are digital, with a flat screen. You can't have parallax error with a screen because there is no distance between the needles and the reference measurements.


Cellular communication has multiple issues:

When a plane is up more than a few thousand feet, a cell phone would see, and try to talk to, multiple cell towers at once.  At best, this is inefficient and overloads the cell network.  At worst, the network can get confused and drop calls.  (not something you want when trying to get ATC directions)
When a plane is moving rapidly, it will change cell towers frequently.  This has the same problems as above.
Cell communications is designed for Person-to-Person during a single call.   Aviation radio is designed so that everyone can hear everyone else's communications.  Even if an ATC instruction is not specifically for me, I can get a mental picture of what other planes are nearby and what they are doing.  This is not so easy with cellular.
In many rural areas, cell phone coverage is limited.


What altitude to use for IFR off-airways route

This article covers the topic quite nicely

To begin with, a direct route will only be approved in a radar
environment. In many areas of the country this is not an issue. The
pilot, however, must be aware that filing an altitude at or near the
OROCA (Off-Route Obstruction Clearance Altitude) may not guarantee
radar coverage. In that case, the pilot should expect to be assigned a
different altitude or route.

Its also covered in this AOPA article a bit

If you plan a "direct" flight, point-to-point, follow the rules and
enter the correct equipment. For example, if "/G" (or "slash Golf,"
meaning that your airplane is equipped with an IFR-approved GPS and a
Mode C transponder) or "/I" (you have loran or VOR/DME and a Mode C
transponder) are not entered for these kinds of flights, the air
traffic control computer will reject your flight plan because that
route can't be flown with less capable equipment. Direct routing
requests also are approved only in a radar environment, so forget
about filing direct, off-airways when radar is not available, or in
areas of poor radar coverage.

So broadly speaking you can file the OROCA but ATC may issue a higher altitude for radar coverage reasons. I have also received direct routings en-route at previously filed altitudes if they meet the requirements. Where I fly its common for ATC to prefer an airway route to get you out of the terminal area but will generally clear you direct once in route.


Why do airliners park with the nose facing the terminal?

To park a passenger plane with its tail towards the terminal has several disadvantages:

it would require a pushback tractor (plus personnel) to do that. Thrust reversers in general are not meant for making the plane go backwards. If it was possible for the plane to go autonomously backwards, it would be extremely = too risky.
you would also need the pushback tracktor for leaving the gate, you couldn't use engines because of the jetblast hitting the terminal
you could not use the APU because it would scorch the terminal
the horizontal tail of some planes might have clearance issues with the jet bridge.
last but maybe not least: the upper class travelers. They sit at the front for a reason: they get on and off the plane first. Yes, the business and first class could be moved to the back. Now, I don't know if riding closer to the cockpit rather than the arse of the plane has some intrinsic value, but at least it is usually noisier at the back.
So customer satisfaction might take a hit there.

So: twice the hassle with pushback + other issues, with no benefits whatsoever.


Do surfaces ahead of propellers decrease thrust?

does having a surface above a propeller decrease its thrust?

Anything that can prevent or reduce the acceleration of air will reduce the effective thrust of a propeller.  That might include obstructions in front of or behind the propeller.

  Why did my experiment showed different results than the blimp.

First of all, I don't see any information about the blimp.  Perhaps it too is greatly affected.  I don't know how much thrust is required in this configuration.  It may be tiny compared to the thrust available when pointing fore-aft.  If true, both propellers have reduced efficiency.

Second, I would think there's a big difference between a flat obstruction and a smoothly curving one.  Your experiment would be closer to the blimp situation if you put a large blimp shape over the propellers rather than a flat sheet.


Where exactly are the heating elements in the PA-28-180's pitot mast?

You don't actually need to get into the mast to know if the pitot heat is working. I fly a PA-28 and during your preflight check if you engage the pitot heat and allow it to run for a minute or two the pitot tube should be warm to the touch. If it is not your pitot heat is not working (or is not reliable enough for flight).


Is it Legal to listen to Air Traffic Control Frequencies in the USA on a computer for entertainment?

Yes it is legal in the US, and you can listen to audio streams on websites such as https://www.liveatc.net


What is the difference between EPR and rotor speed as thrust setting parameter?

While the true 'reason' is probably buried in some engineering notebooks from 60 years ago, it basically boils down to a design decision by the team designing the engine controls.  Both methods work, and both companies have a list of reasons why they think their solution is 'best'.

P&W will tell you that EPR is a better indication of engine thrust, and they're right.  But it relies on pitot probes to measure the pressures within the engine.  Flow stability means response can be slow or erratic and the probes can be clogged causing problems. OTOH, it can indicate problems (unrelated to the probes) due to engine damage.

GE prefers to use N1.  This is a simple speed indication of the fan.  It's not a direct indication of thrust but is directly correlated.  The big advantage is that it is extremely reliable and stable.

A good explanation is available from the Flying Engineer.


How long does it take for an airline to establish a new international destination/route?

In Australia:

Our major airlines quality for what is called an "area AOC". That means they already have permission to operate ad hoc services to any port in Australia and in fact most other countries. All they need to do is an internal risk assessment specific to the new port and address any findings from that (e.g simulator sessions, maybe an on-site inspection), and share it with the regulator. This process can take as little as a few days if it's a simple well-established airport.

If they want to start new regular or RPT services, it's a little more complex in that they need to have a line maintenance facility at the new port, or contract another company to do it for them. This facility is inspected and approved by the regulator which can take a few months to arrange.

You also need government approvals to operate the route, both for the arrival country and overflight arrangements (though typically those are already in place from existing routes). Some countries can be a beaurocratic nightmare and take months to give this, others much quicker. Airports are similar, negotiating parking fees and reserving slots if required.

So to summarize, approval for a one off charter to a familiar port can usually be arranged within a week or two, a regular service needs a couple of months. Of course it can vary wildly depending in the scope of the operation, and I'm ignoring the sometimes years of economic research and monitoring that goes into deciding whether a route is even financially viable.


Have B-25's and B-26's been converted for private business use?

IMDB:

  McCall's plane is a demilitarized Douglas A-26 Invader, a type used in WWII.

Since the film was made in 1960, I imagine there were plenty of them around.

(The A-26 was known a the B-26 from 1948 to 1965, according to Wikipedia. The B-25 is easily distinguished because it has the twin tail.)


Would a airfoil move backwards if you rotate it vertical

A practical example of your question is when a model aerobatic aircraft with a conventional aerofoil profile (ie, not symmetrical) is fitted with a sufficiently powerful motor that it can be made to hover in the vertical position. This is quite a common trick.

The answer is yes, there is a force in the direction of the red arrow.

The model might drift in that direction, although there are other aerodynamic forces, torque, centre of gravity & thrust vector issues that will affect the balance, and these will change as power is increased and the model goes from hover mode to vertical flight mode.


What is the reason for this unusual flight path?

My guess is the captain requested and the dispatcher approved an excessive amount of fuel to deal with the crossing of the long line of weather.  The flight plan would have to reflect being able to burn off that excess fuel to be able to land BELOW the maximum landing weight of the plane. The crossing consumed far less fuel than expected so the crew had to burn off the excess fuel by flying the filed flight plan.  Or they could have just wanted to fly the filed flight plan because flight crews get paid by the hour and they would have just about doubled their pay for that leg.


How can I recognize Taylorcraft BCS-12D-4-85?

That airplane is registered as a 1946 BC12-D per the FAA's N number lookup service.  This indicates that it came from the factory as a BC12-D but then may have been converted later.  Conversions don't change the subtype.

As far as recognizing specific subtypes of old airplanes, good luck!  Many old, popular planes have undergone all kinds of conversions.  Bonanzas built as early as the 1940s can be converted to look like a late model V35B from 1981!  There are even mods to remove the V tail and replace it with a "normal" tail.  My point is that determining subtype from appearances alone may be impossible.

Link below...

https://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=N43459


Can the RAM AIR valve cause depressurization on the CRJ-900?

No RAM AIR VALVE can open if the cabin pressure exceeds the outer pressure. For the CRJ the RAM AIR VALVE is directed so that a dynamic component of the aircraft speed helps its opening, but this is much lower than the difference of pressure between cabin pressure and the outside pressure at high altitude. So no danger of depressurization whatsoever.


Is the distance to PNR (point of no return) affected by wind?

Well, short answer: yes. Intuitively how could the wind not affect the PNR?

But, intuition, especially mine, is sometimes wrong, so let's see. I seem to remember this one from an algebra class, so I took a moment to figure it out. However, my aging brain was obviously going to take a more than a moment (my last algebra class was more than 50 years ago) thus, lazy soul that I am, I went to skybrary.aero and found:

(skybrary.aero)

Let's say we've got 2400 nm to fly in a 500 kt airplane facing a 100 kt headwind. Thus

D = 2400, H = 600, O = 400 and the PNR (ETP) = 1440 nm.

In a no wind situation the ETP (Equal Time Point) would obviously be 1200 nm, so wind does effect the the ETP.

In real life things are not so simple, and flight planning software will take care of calculating such things using winds aloft forecasts along the route of flight as well as other things.


Is there a minimum amount of time an airline has to leave between using two identical callsigns?

Airlines work to make sure there is no duplicate callsigns in the same area at the same time. But there is no regulation for time between the reuse of a callsign.
They achieve this by either a callsign being used only once per day or with enough time between flights that there is no chance for both flights in the air at the same time.
The issue comes if two aircraft are in the air with the same callsign. The air traffic control systems will not be able to tell an ATS message (e.g. DEP, EST, CNG) for one aircraft from an ATS message from the other aircraft with the same callsign. Plus many other issues.
So if an airline needs to use the same callsign twice, like if the first flight is really delayed, they tend to append a letter to the end of the callsign, for example UAE212 becomes UAE212C.
Not asked but for completeness; there is also a risk if the callsigns are close but not the same, for example United 222 and United 232, there could be confusion between the aircraft over the radio. In these situations the air traffic controller can change the callsign to make sure there is no confusion. This could be while they are in the same airspace or for the entire flight.
The risk of callsign confusion has been documented many times in many incidents around the world. e.g. May 10, 2004 near Julian, California Callsign Confusion