Will driving experience benefit flight training?

I don't think driver training is beneficial to flight training, the physical acts of driving and flying are too dissimilar. Driving is a handy skill to have for sure, it's usually much easier to get to the airfield for one thing, it's not going to translate to flying though.

As for flying the numbers you are falling back on what you are good at: attention to technical detail. Attention to technical detail is a very good thing in flying - having a plan and rehearsing for emergencies can save you neck. What your instructor may be telling you is that you need to focus your attention to other details. You may be spending too much time looking at your instruments and not enough looking outside. I did this at first because I had spent a lot of time playing flight simulators and I'm also in IT and spend a lot of time looking at displays in front of my face. The cure is simple: force yourself to get in the good habits of looking outside the aircraft and developing situational awareness. You can only get that through flying practice.

It sounds like you are concerned that you don't have a sort of instinctual "feel" for flying. Everyone has a different set of aptitudes, some people are better at certain aspects of flying than others. If there's an area you are weak in then focus your training and practice on developing it into a strength.


Is an aircraft capable of flying at 900 km/h at 8000 metres above ground?

It is possible, but it is quite fast.

900 km/h is 486 knots.

Assuming no wind and a standard atmosphere, 486 knots ground speed is 486 knots true airspeed (TAS), which is equivalent to a calibrated airspeed (CAS) of 334 knots at 8000 meters.

At that altitude, the maximum operating speed (Vmo) is usually the limiting factor; if you are a kilometre higher then the maximum operating mach number (Mmo) will typically become limiting.

334 is above the Vmo of some airliners (they will need a little bit of tailwind to achieve 900 km/h over ground at 8000 meters), but many are capable of achieving it without wind.

Some examples of Vmo:

Boeing 737: 340 kts (350 kts for the Original's)
Airbus A320 family: 350 kts
Boeing 747: 365 kts
Boeing 777: 330 kts
Airbus A330: 330 kts
Airbus A340: 330 kts


Are there non-economic barriers to a 1000 passenger aircraft?

If money is no object, and we ignore terminal constraints, then no, there isn't. The A380 already supports 850 passengers in a single-class layout, and Airbus has plans to make a stretched version (the wings are designed to give room to stretch the fuselage without needing too much redesign). 1000 passengers isn't really that much of a stretch; we can basically get there now. The issue is that economic obstacles are very real obstacles to building planes; no one has a need for a 1000-person plane on any route (the A380 isn't even used today with max capacity, it's used to give lots of space to first-class passengers with a bit over 500 passengers).

There are certainly at least two airfields out there that would be able to handle a 1000-passenger A380; unfortunately, neither is a commercial airport (the two are Edwards AFB and the Shuttle Landing Facility; the SLF has a 15,000 foot runway that's 300 feet wide, while Edwards has a similarly-sized paved runway). However, if operation is uneconomical, you won't see anyone building a plane to do it.


Should I log flying lessons from the start?

Yes, you should be logging from the start. Now for the first few lessons, it'd be ok to not have your own logbook yet, but you should get one. Hopefully your instructor has kept his up to date, and can build your logbook in terms of flight times since you started.


How do 3d panel methods model wake-surface interaction?

This has a couple parts to it, and it illustrates well the flexibility of well-designed panel methods.

First: panel methods can quite easily model multiple, disconnected surfaces simultaneously.  Select a proper implementation of the Kutta condition such that a trailed wake can be created, and you're all set.  The trick is to just make sure that all panels are considered as interacting with each other.  I've read a couple papers with section detailing this, including Sizing Tool for Quadrotor Biplane Tailsitter UAS by Strom.  Whereas, for one wing, you can compute the influence of all singularities on a given panel, for multiple bodies/wakes, you just compute the influence of all singularities -- regardless of what body they belong to -- on a given panel, be it on-body or in the wake.  For lifting panels (i.e., panels associated with a body that should have some nonzero trailed vorticity), the Kutta condition can be computed in the same way (e.g., for an equal-pressure, nonlinear Kutta condition, the strength of a shed wake panel is determined numerically to correspond with the shed wake of any other lifting bodies such that the Kutta condition is satisfied for all shed wake panels simultaneously).

Now that you have a wake and it is being convected in some manner, we get to the question of what to do when multiple bodies are in close proximity and the wake is predicted to convect through a body.  I've seen this treated in a rotorcraft paper (where the rotor wake is impinging on the fuselage) by Govinderajan in Contributions Toward Understanding the Effects of Rotor and Airframe Configurations on Brownout Dust Clouds.

The rotorcraft problem uses a proscribed displacement to keep the impinging rotor wake out of the fuselage.  As shown in the image below (from Govinderajan), the lines represent a straight-line vortex filament connecting various control points along the predicted wake structure.  The dashed blue line/blue dot are the predicted location for the convected wake.  Since the control point is located in the interior of the fuselage, it is moved radially outward to a point 1.1 radii from the center of the fuselage (green dot above fuselage).

A similar procedure is also followed by Lorber and Egolf in An Unsteady Helicopter Rotor Fuselage Interaction Analysis and appears to be also present in Quackenbush et. al's Vortex Methods for the Computational Analysis of Rotor/Body Interaction, all of which present methods that can predict the performance of various aircraft quite well in comparison to experimental data.  Unfortunately, I don't have a comparison to other methods for you, but this seems to be fairly common.


Does a large simulator bay have standard public address announcements?

My experience with the military is that loudspeaker announcements like this do NOT occur in simulator buildings.  They would be both distracting and largely unnecessary when there are land lines and published schedules available.

Besides the simulators themselves there are briefing and debriefing rooms where crews and instructors are discussing conduct of the events.  Frequent loudspeaker announcements would interrupt these discussions and negatively impact the learning process.

A simulator building is much closer to the environment of a classroom or library than it is to a busy airport, train station, or other public area where you would hear announcements of the type you describe.

Depending on how much realism you are striving for there are some distinctive sounds you will hear in a room full of full motion simulators. These range from the low frequency industrial hum of HVAC and equip cooling fans, to the higher pitched whine of hydraulic pumps, to the swoosh and thump sounds of actuating cylinders moving and hitting bump stops during more aggressive motions associated with unusual attitude or spin recoveries. Up at the control console it will be a bit more muted, but you will hear the crew ICS and radio communications over a speaker, stall warning horns, GPWS alerts, etc.


How do pilots use stopway, EMAS, clearway and displaced threshold?

This is a loaded question.  Every regulation in aviation seems to be written blood and the need for runway safety areas (RSA) is no exception.
RSAs are defined in AC 150/5300-13A

Runway Safety Area (RSA). A defined surface surrounding the runway prepared or suitable for reducing the risk of damage to aircraft in the event of an undershoot, overshoot, or excursion from the runway.

RSA's were developed for specific reasons and are discussed in section 307 of the AC.

In the early years of aviation, all aircraft operated from relatively unimproved airfields. As aviation developed, the alignment of takeoff and landing paths centered on a well-defined area known as a landing strip. Thereafter, the requirements of more advanced aircraft necessitated improving or paving the center portion of the landing strip. While the term “landing strip” was retained to describe the graded area surrounding and upon which the runway or improved surface was constructed, the role of the landing strip changed to that of a safety area surrounding the runway. This area had to be capable under normal (dry) conditions of supporting aircraft without causing structural damage to the aircraft or injury to their occupants. Later, the designation of the area was changed to “runway safety area” to reflect its functional role. The RSA enhances the safety of aircraft which undershoot, overrun, or veer off the runway, and it provides greater accessibility for fire-fighting and rescue equipment during such incidents.

Runway safety areas surrounding a runway is typically twice the width of the runway and 1000' longer than the runway on both ends.  The 1000' of additional length is referred to as a runway end safety area (RESA).  Objects inside the RSA must have specific function and be frangible (fall down) if hit by an aircraft)

AC 150/5300-13A Figure 3-5
Let's talk about runway end safety areas (RESA).  The 1000' feet of additional space beyond the end of each runway is now mandatory.  Every airport must have a RESA at the end of the runway.  The only exception to that rule is runways with an EMAS installed.  The 1000' is not an arbitrary number either.  Through analysis of aircraft overrun incidents from 1975 to 1987 it was determined that approximately 90% of the overruns stopped within a 1000' past the end of the runway at speeds less than 70 knots.  See AC 150/5220-22a for reference.
There are airports that cannot comply with the RESA requirement due to topography, roads, railroads, houses, etc.  In these situations, the FAA has established a concept called declared distances that will push the RESA onto the runway.  This will limit the accelerate-stop distance available (ASDA) and landing distance available (LDA) values.  Airports that cannot comply with the RESA standard are limited to a runway length which is available and suitable for preflight planning purposes.  It would be impractical for the FAA to tear up perfectly good runway.
This means pilots must reference declared distance information from the current chart supplements booklet to take advantage of runway safety protections.
Take a look at KSAN runway 09 end.

Google imagery from KSAN Airport
A 1000' RESA lands in the middle of shopping center.  In this case, the RESA is moved onto the runway.  The pilots must reference the chart supplements to determine usable lengths for takeoff and landing.  Here is the declared distances from the chart supplements booklet.  The runway length is 9400' but the ASDA and LDA values 1,121 feet shorter due to no space for a RESA at the end of the runway.

Chart supplements information for KSAN
Other parts of a RSA include a runway protection zone (RPZ).  This area extends up to 1700 feet past the end of the runway and can be as wide as 500 feet depending on the type of aircraft the runway was designed for.  A little history on RPZs

Approach protection zones were originally established to define land areas underneath aircraft approach paths in which control by the airport operator was highly desirable to prevent the creation of air navigation hazards. Subsequently, a 1952 report by the President’s Airport Commission (chaired by James Doolittle), entitled The Airport and Its Neighbors, recommended the establishment of clear areas beyond runway ends. Provision of these clear areas was not only to preclude obstructions potentially hazardous to aircraft, but also to control building construction as a protection from nuisance and hazard to people on the ground. The Department of Commerce concurred with the recommendation on the basis that this area was “primarily for the purpose of safety and convenience to people on the ground.” The FAA adopted “Clear Zones” with dimensional standards to implement the Doolittle Commission’s recommendation. Guidelines were developed recommending that clear zones be kept free of structures and any development that would create a place of public assembly.

AC 150/5300-13A Figure 3-17
Take a look at KSAN runway 9 again and you will see that the runway does not have space for a runway protection zone at the end of the runway.  A RPZ is mandatory and so the RPZ is moved onto the runway.  The takeoff runway available (TORA) is also 1,121 feet shorter than the runway for just that reason.
For takeoff performance calculations, pilots are required to ensure the airplane takes off and climbs to at least 35 feet within the TODA distance to achieve the designed safety in the RPZ.

Clearways are a special type of RPZ that will not allow any obstacles other than lights that are less than 26 inches in height.  The clearway must be at ""least 500 feet wide centered on the runway centerline and the length may not be more than 1/2 the runway length."

A clearway increases the allowable aircraft operating takeoff weight without increasing runway length.

In other words, takeoff distance available (TODA) is increased beyond the runway when a clearway is installed.

Displaced thresholds are created for four reasons that are beyond the power of the airport owner / operator.

A means for obtaining additional RSA prior to the threshold.  See
paragraph 307.
A means for obtaining additional runway object free area (ROFA) prior to the threshold.  See paragraph 309.
A means for locating the RPZ to mitigate unacceptable incompatible land uses.  See paragraph 310.
Mitigation of environmental impacts, including noise impacts.

Let me answer your questions to the best of my ability
What is the difference from a regulation point of view?
A stopway is designed to allow an aircraft to stop during an aborted takeoff.  Interestingly enough the AC 150/5300-13A does not say it is designed for runway overruns during landing or undershoots on the opposite runway.  By design it will increase the ASDA value for the runway
An EMAS system replaces a stopway and is usable for undershoots while landing on the opposite runway and overruns during both takeoff and landing and is not intended to meet the definition of a stopway.  An EMAS will not increase the ASDA value for the runway

How does the pilot know if this is a stopway where braking is desired, or an EMAS where thrust reversers might be hazardous.
The chart supplements book contains information on all EMAS systems.  Looking at the declared distances for the airport will indicate the presence of a stopway when the ASDA value is greater than the runway length.  Take a look again at KSAN and you will see a note for an EMAS off of runway 27.

Chart supplements information for KSAN
Stopways are a little harder to notice but can be spotted by noticing the ASDA value is greater than the runway length.

How do pilots use non regular runway portions such as clearway, stopway, EMAS, displaced threshold, and possibly more of this kind if it exists and is there some regulation which limits them for taking off, taxiing, or landing?
What are Runway Declared Distances?
This is the easiest question of the bunch.  Pilots are required to use the applicable declared distances for takeoff and landing performance calculations.  By design declared distances take into account all of the airport design standards such as clearway, stopway, EMAS and displaced thresholds.
Declared distances bridges the gap between runway design standards and aircraft performance.

§91.103   Preflight action.
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight. This information must include—
(a) For a flight under IFR or a flight not in the vicinity of an airport, weather reports and forecasts, fuel requirements, alternatives available if the planned flight cannot be completed, and any known traffic delays of which the pilot in command has been advised by ATC;
(b) For any flight, runway lengths at airports of intended use, and the following takeoff and landing distance information:
(1) For civil aircraft for which an approved Airplane or Rotorcraft Flight Manual containing takeoff and landing distance data is required, the takeoff and landing distance data contained therein; and
(2) For civil aircraft other than those specified in paragraph (b)(1) of this section, other reliable information appropriate to the aircraft, relating to aircraft performance under expected values of airport elevation and runway slope, aircraft gross weight, and wind and temperature.

The AIM has information concerning runway lengths.

4−3−6. Use of Runways/Declared Distances
4-3-6(c)(1) Declared distances for a runway represent the maximum distances available and suitable for meeting takeoff and landing distance performance requirements. These distances are determined in accordance with FAA runway design standards by adding to the physical length of paved runway any clearway or stopway and subtracting from that sum any lengths necessary to obtain the standard runway safety areas, runway object free areas, or runway protection zones. As a result of these additions and subtractions, the declared distances for a runway may be more or less than the physical length of the runway as depicted on aeronautical charts and related publications, or available in electronic navigation databases provided by either the U.S. Government or commercial companies.
4-3-6(c)(2)(c) When considering the amount of runway available for use in takeoff or landing performance calculations, the declared distances published for a runway must always be used in lieu of the runway’s physical length.
4-3-6(c)(2)(d) An aircraft is not prohibited from operating beyond a declared distance limit during the takeoff, landing, or taxi operation provided the runway surface is appropriately marked as usable runway.

AIM Figure 4-3-6
How do you use declared distances for multi-engine pilots?
How do runway declared distances affect my takeoff distance?
The short version is aircraft utilizing balance field length calculations typically provide a single distance for takeoff that must be lower than both the TORA and ASDA value.
Aircraft with unbalanced field length calculations typically provide separate performance calculations for accelerate-go and accelerate-stop. The TODA and ASDA values must be greater than the calculated accelerate-go and accelerate-stop distances, respectfully.

TL;DR version
Pilots using applicable declared distances are afforded designed runway safety area protection.  Pilots who choose not to adhere to runway declared distances risk getting outside the protections designed for the runway.


I have a document referring to aircraft with maximum takeoff weight of 45000T. Is this an error?

It stands for metric tons, as indicated in the "GEN 2.1 Measuring system, aircraft markings, holidays" section of the AIP that you linked to as one of the units for mass.

That being said, the number format appears to be wrong and they most likely intended 45.000 metric tons, which works out to about 99,000 lbs. and is a somewhat common point to use for aircraft classification in other countries.


How to differentiate two flights with the same flight number that arrive on the same day?

I'm making each days flight unique based on flight number and the date that it arrives.<

A standard used by some (most?) airlines is to refer to the flight by the Flight No and by the departure date (you've already discovered the problem with using arrival dates).

So your example flights would be LS1494/<Sunday date> and LS1494/<Monday date>.


On a chart, how can I find the frequency for flight following?

In the United States, you can consult the VFR Sectional Chart and look for the frequency box located near a terminal area.

Otherwise you'll need to consult the Airport Facility Directory for the region your are flying to find a ARTCC (Center) frequency.


How accurate must fuel gauges be for VFR flight?

The indicator must be calibrated to read zero when that tank is actually empty of all usable fuel (in level flight).  Bouncing is fine as long as they do not bounce when the tank is actually empty.

See regs:

23.1337
91.205


There is more to a T-tail than that:

Aerodynamics:

The placement on top of the vertical gives it more leverage,
especially with a swept tail.
Depending on wing location, it stays in undisturbed flow in a stall. Note: This is really depending on the details, the HFB-320 had a forward swept wing and a T-tail, which made a deep stall possible (and in one case fatal).
By designing the junction with the vertical well, the T-tail has less interference drag. It also helps to reduce wave drag, especially when using a well designed Küchemann body (the round, long, spiky thing on the tail junction of a Tu-154) by stretching the structure lengthwise.
It can help to increase the effectiveness of the vertical tail by keeping the   air on both sides of it separated. At the other end, the fuselage does this already, so moving the horizontal tail up does not hurt so much there. As a consequence, the tail can be built lower.

Structure:

The mass of the horizontal tail on a long lever arm (= the vertical tail) means that the torsional eigenfrequency of the fuselage will go down. This might be a problem in case of flutter.
As a consequence of the smaller vertical tail, a T-tail can be lighter. Note that the increased leverage means that the horizontal tail can be smaller as well. This reduces friction drag and is the main reason why most modern gliders have T-tails.

Control:

A T-tail produces a strong nose-down pitching moment in sideslip.

If it were not for the flutter and pitch-down, T-tails would be more widespread ...


What flight and route information do pilots need for flight?

I might be able to help a little, I am a professional software developer and also a recreational pilot in Australia.

Starting firstly with the requirements for such a site.  Data for different countries is often sourced from different locations, so you would need to investigate that.  I can only speak for Australia, but we have a web service that we can log into which provides us with weather briefings (METARs, SPECIs and TAFs, as well as ATIS for some Class C airports) and NOTAMs, and which also allows us to submit flight plans.  There are a few apps available which link in with this system, and you could definitely get yours to do the same.

Charts are again something that will differ between regions, and you will need to source these.

On to flight planning itself, you've mentioned the basic things you need.  I only file VFR flight plans, so I can only speak for those.  I start by finding my origin and destination on my charts and ensuring I have all the charts required for the flight, and that they are all up to date.  I have a look for any PRDs (prohibited, restricted or danger airspace) along a direct route, and plan around them by selecting waypoints that will take me on a track away from them.  I avoid controlled airspace where possible and look for major landmarks that I can use as visual cues along the way.  If your system could tell me straight away what PRDs I'll be breaching, whether they are active (from the NOTAMs), and if so, plot a course away from them, that would probably make it stand out from the crowd.

Once I have my route, I look at the LSALT (lowest safe altitude) along it (by looking at the terrain elevation and any obstacles), and work out my cruising altitude, conforming to the hemispherical level rule (odd altitude for track 000-179, even altitude for 180-359, plus 500 feet for VFR).  Again, your system could look at the terrain in the area and suggest an altitude for me which conforms with this rule.

Once I have my exact route (both horizontal route and vertical route), I work out my TOD and TOC (top of descent and climb), mark those on the charts, and then work out my fuel burn by looking at the forecast winds at each level and calculating how much head/tail wind I will have, plus any offset I need to counteract any crosswinds (which may affect my groundspeed if the offset is large enough).  There are a few apps out there now that will do this all for you, so I would expect you would want your system to do the same.  If you're serious about this project, I would recommend getting your hands on a wizz wheel and learning how to use that.  That'll give you a good idea about how the calculations work, and you should be able to make a few algorithms from that.

To give you an idea, below is my flightplan from a few days ago:

Then it's a matter of filing the flight plan and going for a fly.


Sure it can.  It's just vector math.

$$\vec{A} + \vec{B} = \vec{C}$$

If $\vec{C}$ is your ground speed vector and $\vec{A}$ is your airspeed vector (magnetic heading with true airspeed as a magnitude, then $\vec{B}$, the wind vector, can be solved for by

$$\vec{B} = \vec{C}- \vec{A}$$

Electronic flight computers and E6B apps for tablet computers/smartphones can do the same thing.  But it's nice to have some basic skills with a whiz wheel.


Costa Rica landing in the news, concerns to be taken seriously?

Please don't link to media articles in the general press, but especially not the Daily Mail who generally don't worry too much about facts and have no-one on staff who has a clue about aviation ("activate their tyres in time", "With its landing gear ejected, the plane comes perilously close to hitting ground level too early").
Just look at the rhetoric in the wording of the article body.  It ticks all the boxes:

...within a few feet of terrified drivers...
...Shocked passengers on board...
...eye-catching video...

The Daily Mail tries to get at least one of these a month as clickbait and for comments.
Some critical thinking.

...grazed perimeter fence...

No evidence presented.

...why so many photos...

Because the road is right at the end of the runway and spotters gather there to take such photos.

...passengers shocked...

No evidence presented and most passengers are the worst possible judges of a good approach or not. How would they know?

...how low was it at the threshold?...

No evidence presented.

...airport authorities insist it was a normal and 'controlled landing'...

What evidence is there that it was not?
SJO is known for its tricky and low approaches.  Nothing to see here.


How does a supersonic jet engine differ from a subsonic jet engine?

Thrust is air mass flow multiplied by the speed difference between flight and nozzle speed of the engine. To increase thrust, subsonic engines try to maximize mass flow (by increasing the bypass ratio) while supersonic engines rely more on increasing the nozzle speed (by using afterburners).

The core engines do not differ much - after all, the intake will make sure that air reaches the engine at a speed of Mach 0.4 to 0.5, regardless of flight speed. The main difference is in their bypass ratio. The slower the design speed, the bigger the bypass ratio may become. At very low speed, the ungeared, shrouded fan is exchanged for a geared, free spinning propeller, in other words, the jet changes to a turboprop. The intake and nozzle, however, are very different indeed.

The optimum bypass ratio changes continuously, but since the drag coefficient drops after crossing Mach 1, airplanes are either designed for a maximum Mach number of 0.9 or less, or 1.6 and above. The corresponding bypass ratios today are up to 12 for subsonic engines, and less than 1 for supersonic engines. This produces a sharp boundary at the speed of sound, and many military engines designed for supersonic flight lost their afterburners and were fitted with a big fan to become the engines for subsonic transport aircraft. Examples are:

The Pratt & Whitney J57 turbojet (installed in the F-100 and F-102 fighters, among others) became the JT-3D turbofan which powered the Boeing 707 or the DC-8.
The core of the General Electric F110 (installed in the F-15 and F-16 fighters, among others) became the CFM-56 turbofan which is used in the Boeing 737 or the Airbus A320.

The differences between sub- and supersonic engines grow bigger the more you move away from their core. High-pressure compressor, combustion chamber and high pressure turbine look and work the same, but the low pressure compressor of subsonic engines swallows a lot more air and has a much bigger diameter. Supersonic engines in turn mostly have an afterburner. The biggest difference, however, are the intakes (large pitot intake with blunt lips for subsonic aircraft versus adjustable spike or ramp intakes for supersonic flight) and the nozzle (fixed for subsonic flight versus a complex, adjustable convergent-divergent nozzle for supersonic flight). This is due to the very different air speeds and the much higher exit velocities required for supersonic flight.


Can TCAS give an RA for one aircraft and a TA for another?

It's hard to give a definitive answer without more information.  My go-to for TCAS details is the FAA's Intro to TCAS II. In general, an RA will try to coordinate with the other aircraft, but such coordination doesn't require the other aircraft also issue an RA, it only listens for other RA "intent" messages and makes sure it doesn't issue a conflicting RA.

Here's some possibilities:

A marginal RA encounter.  Each airplane has slight differences in calculation , so, as the FAA manual linked above reads, "In a majority of the TCAS/TCAS encounters, the two aircraft will declare the other aircraft to be a threat at slightly different times"
The TCAS of one aircraft was set to TA-ONLY, although this normally only happens if the airspace is busy
One had an inaccurate pressure altimeter reading
Thresholds are larger at higher altitudes and this could have contributed to the higher altitude pilot receiving only a TA
One airplane was running TCAS I instead of TCAS II and couldn't get RA's.  This is probably not the case if the aircraft was commercial.
They're running different versions of TCAS with slightly different algorithms


What options do pilots and mechanics have when an aircraft owner doesn't pay up?

You should be able record a lien against the aircraft.
Avionics News ran a Legal Ease piece about just this, which is well worth reading fully:

If a lien is properly asserted, the lien claimant (the aircraft mechanic) has encumbered the aircraft in question, meaning the aircraft no longer has clear title.
Clear title is highly desirable to an aircraft purchaser, who can determine if an aircraft has any liens on its title through a simple title search. Once there is a lien on an aircraft, to sell the aircraft with clear title, the aircraft owner must obtain a release from the lien claimant. This means the owner must pay you for your services before they are able to sell the aircraft with clear title.
If the owner fails to pay the lien claimant to have the lien lifted, the aircraft will be sold subject to the lien. This means the aircraft does not have clear title, and although the aircraft will have a new owner, your lien will remain in effect.
Most buyers, however, will not purchase an aircraft subject to a lien, and thus, you usually will manage to receive the money owed to you when the owner decides to sell the aircraft.
If you do not want to wait for the aircraft to be sold to satisfy your lien, you can bring a foreclosure proceeding, forcing the sale of the aircraft, usually at an auction.
The proceeds from this sale go to the lien claimant to extinguish the lien. If the proceeds are greater than the lien, any money exceeding the amount of the lien goes to the aircraft owner. Additionally, if there are no bidders at the sale (an unusual occurrence), the aircraft may be given to the lien claimant for the price of the lien.

One thing worth bearing in mind, is the Aero Liens List - a free resource which lists liens placed against aircraft owners. If your new client is on their "deadbeat client list" then you may want to think twice about doing the trip or get paid in advance!
You asked whether a lien could be registered by a pilot for lost wages (rather than a mechanic for lost labour/parts); just searching the above list for "John", I found at least one pilot who has two liens (against seperate companies) for lost wages: #1 #2
Another lien (PDF unavailable) lists its nature of the claim as "Salary owed".


Which Velocity is used to measure Dynamic Pressure?

You should use the speed of the air relative to the object.

Take the extreme example of a stationary wind turbine. It obviously experiences aerodynamic forces and dynamic pressure, yet always has an absolute speed of zero.


How to find black boxes underwater absent any pinger signals?

The CVR on a Boeing 737 is located in the aft cargo compartment. The CVR itself is not built of the same materials as the aircraft, which is mostly aluminium and composites. By mapping the location of other components of the aircraft found in the sea bottom it should be possible to make an educated guess of the general location of the CVR (assuming the aircraft did not disintegrate, sending everything in different directions). One common way of tracking down the CVR is by using an underwater magnetometer to detect ferrous metal objects. The problem is that something as small as a CVR will only be detectable up to about 20' under the ocean floor. If it is buried deeper than that it will be difficult to find. That's why they have pingers, but those stop working when the battery runs out.


Is there any emergency situation in which jet engines would not be shut down before passenger evacuation of a transport aircraft?

It is possible for the engine to not respond to shutdown sequence, so you'd have to get the passengers off before dealing with the rogue engine.

In the Qantas Flight 32 one engine had an un-contained turbine failure in engine No. 2 leaving them unable to shutdown engine No. 1. This was due to a piece of debris severing all communication to the engine, essentially leaving it out of control and running.

This in turn made it impossible for the crew to activate any safety mechanisms for the engine. It was eventually shutdown by dousing it until flameout.

Report by Australian Transport Safety Bureau

Wikipedia Article on Qantas Flight 32

It should be noted that in this specific case they didn't evacuate immediately due to a fuel leakage and the overheated brakes, though when they did evacuate engine No. 1 was still running.

Another situation where immediate evacuation may be preferable is if the aircraft had a cabin fire, meaning the highest priority would be cabin evacuation, which could potentially happen simultaneously to the crew attempting engine shutdown.


Let's see if I can be of assistance.

Q: What is involved in small craft pre-flight inspection?

A: Do a google search for "POH Cessna 152" and you will see many listings showing a Pilot's Operating Handbook (POH) for a Cessna 152 (small craft).  In the POH you will see a section that describes a "pre-flight inspection."

Q:When do you need to, and what is involved in filing a flight plan for a small craft?

A: Click this link (Aeronautical Information Manual - AIM) and look at Chapter 5, section 1, Preflight, and you will see information related to filing of flight plans in the U.S..

Q:What things are looked at most closely during a small craft crash investigation?

A: Click on this link (NTSB - Aviation Accidents). In the search box type in Cessna 152, or Cessna 172, etc, and you will see some accident reports prepared by the U.S. NTSB.  This should give you an idea of what is looked at in a small craft accident investigation.

Q:Is there still a 'black box' on a small craft?

A: Assuming your research involves (U.S.) small craft that are not operated for commercial purposes (generally known in the U.S. as FAR Part 91 General Aviation operations), there has never been a requirement (that I'm aware of) for a 'black box.'


Does oxygen become less available during night-time?

Night vision is one of the first things affected by reduced oxygen levels, and that effect is masked in daylight, but can become consequential at night.  But no, the O2 molecules are the same night or day.

BTW, airline pilots in our 8000' cabins do not have different guidance for putting on the masks -- it's 10k, day & night both. Air Force was, IIRC, the same 10k, with no difference in the rules day vs night.


Which tail type is better in order to obtain higher speed?

Lose the tail.
By Staff Sgt. Bennie J. Davis III [Public domain], via Wikimedia Commons

Split brake-rudders will do the trick.

You can also try and beat NASA and Boeing to the Active Flow Control tails.

Or just settle for a T-tail.

The horizontal tail plate effectively increases the aspect ratio of the fin by virtue of the 'end plate' effect. The T-tail configuration is especially popular on gliders.

(Flight 1977—PDF) Early Boeing 757/767 designs featured T-tails to reduce drag.


What is the purpose of the extra wheel on the XB-70 main gear?

It is a sensing wheel that is part of the antiskid braking system. It contains an electronic sensor to measure the true groundspeed of the airplane. See NASA Technical Note D-4836, Landing Loads and Accelerations of the XB-70-1 Airplane (1968), bottom of page 3 of the document (page 5 on the PDF):


What is the highest a helicopter can fly?

This (and more) is quite easily answered by Wikipedia

Highest altitude without payload
12,442 m (40,820 ft)
Aerospatiale Lama

Highest level flight altitude
11,010 m (36,120 ft)
Sikorsky CH-54 Tarhe

Altitude with 40-tonne payload
2,255 m (7,398 ft)
Mil V-12

Visit the linked Wikipedia article for more records and sources.


Is there any benefit to sweep back on an ultralight?

There are two primary benefits of wing sweep at ultralight speeds. The first is that it acts as variable dihedral -- the higher your angle of attack, the more dihedral effect you get from sweep.

Secondly, when you see ultralights (or hang gliders) with a lot of sweep, it's generally for a tailless design that needs to get the tip fins/rudders and twisted tips and/or elevons back behind the CG location so they have a useful moment arm.

The benefits of sweep in transonic flight (delay of Mach effects onset) obviously don't apply at ultralight aircraft speeds.


Where to do the Run-up and Safety on the Return Flight?

The simplest thing is to ask someone local where runups are usually done: the FBO, Ground Control or another pilot. If you can't find out then you can do them anywhere you like as long as it's safe.

Some airports have specific runup areas but they aren't always obvious. For example, KPDK has runup areas at both ends of taxiway A, they're shown on the airport diagram as 'bulges' in the taxiway but they aren't labelled. You might notice them when you land and taxi but you might not. I've circled one of the runup areas in red here:

If there are no runup areas, the 'default' location is the one you remember from training: on the taxiway just before reaching the runway, angled into the wind. If the taxiway is wide enough, you can move to the edge so that other aircraft can pass you if they're ready before you. That's very common and it's what many pilots will expect you to do, even if you have to block the taxiway for a couple of minutes. This is where you have to use some judgement: if you know that you need to take your time on runups - perhaps it's an unfamiliar aircraft, or you've just had maintenance done and you're double-checking everything - then you might look for another spot where you won't be in the way.

Blocking other aircraft from reaching the runway is always a possibility, but at airports with a lot of GA traffic - and especially a lot of flight training - it's common and just something to be expected. That doesn't mean you should take forever doing your checks and of course some other pilots will always get annoyed at even minor delays, but if the only safe place to do runups is the taxiway then just do them there and the others will wait.

Another option is to do runups on the ramp or before entering the movement area so that you don't block other aircraft anywhere. That's especially important at airports with scheduled commercial flights because they usually have very precise departure times and getting stuck behind another aircraft for even a few minutes could be an issue. If you're in that environment, then you should definitely check with Ground Control what they want you to do. But be careful about doing runups on the ramp because of people and vehicles moving around. Also be wary about doing runups a long way from the runway: during a long taxi you might change something (e.g. the mixture or fuel controls) and then forget to reset it for takeoff.

The one place you should never do runups is on the runway itself. Sitting there for several minutes blocking the runway for landing traffic and unable to see final approach behind you isn't a good position to put yourself in.

Finally, avoiding blowing debris into other aircraft should be simple: just look around you, and don't position the aircraft so that your prop blast is going somewhere it shouldn't.


Could the CVR and FDR record to the cloud?

The basic problem with transmitting CVR & FDR data to the ground from flight is the sheer amount of data that is generated by today's sophisticated airplanes.  There are hundreds of parameters being recorded many times per second plus the voice channels.  Today's airliners record 500 GB of data on each flight.  Take this and multiply it by the thousands of airplanes that are in flight at any given moment, and you can see that there would need to be a lot of bandwidth available for all of it to be transmitted wirelessly.  There would also need to be a world-wide standard developed and hardware deployed so that an airplane can transmit the data no matter where they are.  Airplanes operating in remote locations would have to use satellites, which are relatively low speed and expensive to deploy/maintain/operate.

In short, it just isn't practical with today's technology.


Does FAA simulator (AATD/BATD) count toward experimental rating 1,000 hours requirement?

The short answer is no. As you said in your question, the regulations you quoted require you to have logged flight time, which is defined in 14 CFR 1.1:

  Flight time means:

  (1) Pilot time that commences when an aircraft moves under its own
  power for the purpose of flight and ends when the aircraft comes to
  rest after landing; or

In other words, you have to go fly a real aircraft. And 1.1 defines "aircraft" clearly too, so you can't argue that it includes simulators.

But even if you could use a simulator, you would still need an instructor present. 14 CFR 61.51 talks about logging simulator time for various purposes, but in every case it also says that an "authorized instructor" must be present and endorse your logbook. That makes sense: if you're playing around by yourself in a simulator, you could be doing anything at all, including reinforcing your own bad habits. The instructor is there to ensure that what you're doing is useful and relevant, and you're learning from it.


What is the autorotative rate of descent for a Bell 47-H?

According to this fairly recent flight test...

  As we climbed for an autorotation Sean explained that the yellow line around the bubble effectively demarcates your autorotation options − you can land on anything under the line, you’d be pushing it beyond that. With the inertia of the -23 model blades and their nine-pound tip weights, the entry is smooth and unhurried, the descent at sixty knots bringing up about 1,700 fpm, and the flare stress-free − very different from the crash-bang-wallop engine-offs of the low-inertia world.

Around 1700 feet per minute in auto. The Bell 47 is known to be one of the most forgiving helicopters to autorotate, thanks to the large blades with weights on the tips... what is known as a 'high inertia' rotor system. The opposite is a 'low inertia' rotor system such as the Robinson series, which requires less power in flight, but the lighter blades don't retain nearly as much inertia in an auto, giving one less latent energy to use during the final flare, and a more slender margin of error.

On my daily commute, I used to admire a Bell 47 I'd see out doing traffic reporting duties. An article popped up in the local paper on how that particular 47 lost engine power at 2000 feet... it was fresh out of an overhaul. The 47 was landed with only a ding on one skid... no report on the damage done by the pilot to the mechanic who overhauled the engine, but I suspect it may have been more than a bent skid.


Why does the Biot-Savart law give the induced velocity of a infinitesimal segment of a vortex filament at point P?

Why would

  the induced velocity at a point P of an infinitesimal section of the filament be zero unless $d\vec{l}$ and $\vec{r}$ are perpendicular

?

The cross product in
$$
 \frac{ d\vec{l} \times  \vec{r} }{ \lvert \vec{r} \lvert ^3}
$$

does not change signs when going over the $\frac{\pi}{2}$ angle in between vectors, so the infinitesimal filament sections $d\vec{l^-}$ (immediately before $d\vec{l}$) and $d\vec{l^+}$ (immediately after $d\vec{l}$) have contributions to $d\vec{V}$ that do not cancel each other out. Therefore, $\vec{V}$ is not just a function of a single filament section, but of the entire filament, hence the integral.

If you check the next section in the source of your image, titled Straight-vortex case you will see this in action.


No aircraft ever had more than two pilots (on duty at the same time).

The additional flight crew members were flight engineer, navigator and radio operator.

Dedicated radio operators were only needed in the early days when the radio was primitive and required some care and experience to tune properly. As it improved, operating radio was merged into navigator or flight engineer job and eventually became simple enough for pilots to do themselves.
Navigators were used on long-distance flights especially over water. They kept track of the progress on the map and corrected the position using celestial navigation and some landmarks where available. With advent of inertial navigation systems and long range radio this simplified enough that dedicated crew member was not needed any more.
Flight engineer was most common and remained longest. Engines had many gauges that needed monitoring and controls that had to be correctly set to start them and adjusted to keep them running efficiently. And while turbine engines are simpler to manage than piston ones, the addition of more electric and hydraulic system meant that there was still a lot to set up and monitor. But now this job is done by a computer that monitors all the parameters and displays specific messages when something fails including instructions what needs to be checked and done for each problem.

In the meantime, the improvements in autoflight systems freed more time for the pilots in which they can now handle, with help of the electronics, the tasks that before needed a dedicated crew member.

Due to these technological advances allowing for the removal of these crew members, overall flight safety has not been compromised. It is likely that safety has actually improved by reducing the probability of human error.


does a semi sphere have more drag in comparison to a flat plane with equal surface area?

No it doesn't. This chart explains how.
https://www.researchgate.net/figure/Typical-drag-coefficients-for-regular-3-D-objects_tbl2_273771608


If I'm cleared to land without any specific instructions on how to enter the pattern, what should I do?

Your description sounds like the diagram below, so I'll proceed based on that.
When a controller gives you a landing clearance while you are a ways out with no intermediate instructions, it's usually because there is nobody else around the controller needs to coordinate and you are being given discretion to proceed by the most direct logical routing to get to the threshold of Rwy 5.
Although there is a published "left" traffic pattern, and normally you would follow the usual protocols to get established for the left pattern for Rwy 5, the landing clearance at that stage was granting you discretion to use a right pattern if it was more direct and that's what the controller expected. When you crossed the field to get to the "proper" side (blue line below), this would get the controller wondering what you're up to as you appear to be just flying off to the northwest until you turn downwind, especially if you are in the habit of using wide patterns.
I would have proceeded direct to a right downwind or even a right base leg (red or black line below) if I was already line up for that, and would have mentioned that in the readback for the landing clearance, such as "Cleared to land runway 5, proceeding direct right base", just to let the controller know my intentions, and if there was a misunderstanding, I'd find out about it then.
There is a contributor here who is an air traffic controller, so hopefully he/she will chime in.


How short does a trip need to be before flying is less safe than other forms of transportation?

Note: This does not take travel to/from the airport into account.

The Wikipedia page on aviation safety has a nice table with deaths per journey, time and distance (based on data from the UK between 1990 and 2000):

Car: 40 deaths per billion journeys, 3.1 deaths per billion km
Aircraft: 117 deaths per billion journeys, 0.05 deaths per billion km

Assuming that car accidents are equally distributed along a journey, we only need to consider the 3.1 deaths per billion km. Further assuming that all aircraft accidents are related to takeoff and landing (i.e. once per journey), we only consider the 117 deaths per billion journeys. While the first assumption is probably reasonable (there are differences between types of road though), the second one is not quite true since aircraft can also develop problems during cruise.

With these basic assumptions, we can calculate when the expected number of deaths are equal:

$$ N_\text{death} = 117 \cdot 10^{-9} = 3.1 \times \frac{d}{10^9 \, \text{km}} \; \Leftrightarrow \; d = \frac{117}{3.1} \, \text{km} \approx 38 \, \text{km} $$

So any flight longer than 38km is safer than driving the same distance.

Let us now try to take the cruise part for aircraft into account. According to this page 20% of all fatalities are due to accidents during cruise. We can subtract 20% from the 117 deaths per billion journeys (so this only takes the parts of the flight into account that happen once per journey). Modifying the 0.05 deaths per billion km is not so straight forward. Since most of the distance is traveled in cruise, I am going to be conservative and just leave this number unchanged, therefore providing an upper limit on the deaths per km.

Now, we can make a more accurate comparison:

$$ N_\text{death} = 0.8 \times 117 \cdot 10^{-9} + 0.05 \times \frac{d}{10^9 \, \text{km}} = 3.1 \times \frac{d}{10^9 \, \text{km}} $$
$$ \Leftrightarrow \; d = \frac{0.8 \times 117}{3.1 - 0.05} \, \text{km} \approx 31 \, \text{km} $$

This is actually lower now, because the deaths during cruise are irrelevant for such a short flight. And this gives the final answer: Flights longer than 31km are safer by airplane than driving the same distance by car.


Did the Germans ever use captured Allied aircraft against the Allies?

Not sure about the Germans, but the Italians used a P-38 (from the site 12 O'Clock High):

The piece about the P-38 captured by the Regia Aeronautica is
extremely correct (at last, I was sick of reading accounts or
questions mutuated from the complete fantasy of Martin Caidin...! ),
except for one detail: the plane shot down on August 11, 1943 by Col.
Angelo Tondi with the P-38 wasn't a B-24 but a B-17 instead...

and later on the same post:

This is extracted from the diary of 2nd Lt. James Franklin Boston:
"August 11, 1943-Mission to Terni, Italy 06:00. Carried 6000 lbs.
demos. (demolition bombs). Flak moderate. Coming back 60 miles from
Italy intercepted by ME-109 and captured P-38 with enemy flier flying
it. Nobody fired at first, thinking it friendly. Saw it slip in a
formation from behind and shoot down a B-17. Everybody fired at it
then including myself but my gun jammed. 20mm shell came by my head
while I was looking through astrodome and went into No. 2 engine. P-38
was not shot down."


How to understand the requirements for IFR currency?

The regulation here seems to be 14 CFR 61.57(c)(1). The way that the regulation is written, we can see that there are three separate requirements:

(1) Use of an airplane, powered-lift, helicopter, or airship for maintaining instrument experience. Within the 6 calendar months preceding the month of the flight, that person performed and logged at least the following tasks and iterations in an airplane, powered-lift, helicopter, or airship, as appropriate, for the instrument rating privileges to be maintained in actual weather conditions, or under simulated conditions using a view-limiting device that involves having performed the following -
(i) Six instrument approaches.
(ii) Holding procedures and tasks.
(iii) Intercepting and tracking courses through the use of navigational electronic systems.

So it's not "a combination of the above that total 6", and it's not 6 of each. It's 6 of the first one, and any amount of both of the other two.


What types of fuel quantity sensors are used in an aircraft? How do they work?

From this PPRune forum thread, the Boeing 777 does use ultrasonic sensors (some 20 per tank)

  This airplane has some 20 sensors per tank. Each of these is effectively a "radio doppler" and works on the same principle. The sensor calculates the height of fluid by measuring the difference in the speed of the sonic signal sent out thru one sensor to another,as against the ACTUAL local speed of sound (which is a preset value) thru standard temp air.This difference is then converted very accurately into height in the tank in mm.Which translates into quantity of fuel AT THAT sensor given the actual specific gravity of fuel at that point.
  - King on a Wing


What is the exact definition of Taxi Time?

As always, the definition depends on the context. That is why official documents always included the definitions of important terms used in the text.
For Collaborative Decision Making (CDM) as defined  by EUROCONTROL in the latest CMD manual (2017), taxi time is divided in taxi-out time and taxi-in time.

3.4.2 Definition of Taxi Time
For Airport CDM purposes, taxi time is considered to  be:

For arriving flights: the Actual taXi-In Time (AXIT)  is  the  period  between  the  Actual  Landing  Time   (ALDT) and the Actual
In-Block Time (AIBT)
For  departing  flights:  the  Actual  taXi-Out Time   (AXOT) is the period between the Actual Off-Block Time (AOBT) and the Actual
Take Off Time (ATOT).

For  calculation  purposes  within  the  CDM  Platform, taxi times
will be referred to as estimated taxi-in (EXIT) and estimated taxi-out
(EXOT) as there is no requirement for a scheduled, actual or target
taxi time.

Now that in itself doesn't help if you don't know how the ALDT, AIBT, AOBT and ATOT are defined.
The ALDT is the same as the ATC Actual Time of Arrival, which is the time the aircraft touches down.
The AIBT is the actual time when the parking brakes have been engaged at the parking position. (source)
The AOBT is the time the aircraft pushes back / vacates the parking position. (source)
The ATOT is the same as the ATC Actual Time of Departure, which is the time the aircraft lifts of from the runway.
Now Taxi time defined as above is used in Airport management, Air Traffic Management. It may be different in other areas.
Some observations that I want to make given the above definition:

De-icing on-stand is excluded from the taxi-time. De-icing on a remote de-icing pad is included in the taxi-time.
The take-off run is included in the taxi-time.
The landing run is included in the taxi-time.
Taxiing between stands or to/from maintenance is not defined.


How can I get more details about information in a NOTAM?

What, you dislike the fact that the NOTAM about patchy ice is patchy in its detail? :)

Generally if you need more information about a NOTAM (in the US) you can check with:

Flight Service
While collecting your briefing ask if they have any more detail -- sometimes they do, sometimes they don't, but it's worth asking.
A local FBO
Particularly for FICON NOTAMs - A local FBO will usually know the condition of the field, and often have other useful info for you (like how much a heated hangar is going to cost you for the night).
Airport Operations
Again, particularly for FICON NOTAMs - These guys will usually have a pretty good picture of the field's condition, since they're generally the poor shmucks responsible for doing the snow/ice clearing.

Failing all of those, you can also call the tower phone number at a towered field (you can get that number from Flight Service too) and ask them for details.
I usually make the tower my last resort call - they're almost certainly going to be willing to give you as much information as they can, but they're also busy doing other stuff like dealing with planes taking off/landing/taxiing around & they'd probably appreciate if we tried the other sources first.
The other folks I mentioned generally have someone sitting around to answer phones and questions.
In the case of Flight Service, that's basically their job :-)


Where should I enter the pattern when instructed to report a 2-mile left base?

I'm assuming you're more interested in the base-or-downwind question rather than the where-is-the-2-mile-base question.

Theoretically you're supposed to fly the published procedure unless told otherwise. In this case the procedure would probably be a standard traffic pattern.

Being told to 'report' means only that, you should report it when you're there.

This is not to be confused with the (in my experience) more common instruction "Enter and report a 2 mile base for runway 16", in which case you head for the base and not the downwind, and you report it when you get there. To argue ad absurdum, the clearance "Cleared touch and go, after the touch and go, make left traffic, report mid-field downwind" doesn't mean you should head straight for the downwind.

As always, when in doubt, ask.


Did the twin engined Lazair ultralight have a throttle for each engine?

I've examined a Lazair, and actually taxied one around on the ground once, and yes there are two throttles.

Two reasons:

In any twin engine airplane you want to minimize or eliminate single-points-of-failure (especially with engines as unreliable as little 2-stroke water pump motors) and this means you want the keep each power plant completely mechanically independent all the way up to the throttle.

You need to be able to adjust power independently to synchronize motor RPM (because the wowowowowow of out of sync motors will drive you bonkers), as well as control each engine independently for starting etc.

So, a single throttle to control both engines is a very bad idea.


Why is the center of pressure of a rocket at its centroid?

This answer may not be what you are looking for, but I think the issue is we aren't really talking about the rocket as a "wing" here since these rockets fly ballistically.   I think the term CP in the NASA article would be better expressed as "neutral point", the point at which aerodynamic moments are in balance when the rocket is not aligned with the airflow, taking into account the body and all of its appendages.

So this would include the fins as part of the total lateral area subject to lateral air loads when the rocket yaws while flying ballistically, and to be stable, the rocket's center of mass needs to be forward of the neutral point, so that when it yaws, the corrective moment, acting at the aerodynamic neutral point, is created about the center of mass to bring it back into alignment with the airflow.

The term CP suggests that the rocket is flying like a lifting body wing, with a constant angle of attack and lift being generated to support its weight.  But as a ballistic object, its AOA is always ideally 0 and what lateral aerodynamic forces are being created are strictly to keep the rocket's tail lined up behind its nose as it travels its ballistic path.


Why do propellers on aircraft have a slight offset angle?

The direction of rotation of the propeller introduces an asymmetry which designers try to mitigate by adding more asymmetries. Specifically, a right-turning tractor propeller (clockwise from the pilot's viewpoint) will swirl the propeller wake in the same direction which adds a negative sideslip angle on the vertical tail (which sticks up into the upper half of the wake only). By pointing the axis of rotation of the propeller slightly to the right (right sidethrust), this sideslip angle can be reduced.

Other means of correction like an incidence on the vertical tail would not work equally well: Once the engine is throttled back, such an incidence would require to re-trim the aircraft.

On multi-engined aircraft a sidethrust can help to reduce rudder input in engine-out cases. Here each wing engine points slightly away from the fuselage so its thrust will pull the aircraft into a helpful sideslip when the opposite engine has failed.

The propeller axis can also point slightly down in order to move the thrust line closer to the center of gravity, reducing thrust-related trim changes, and to reduce the P-factor effect (sideways shift of the thrust vector) at high angle of attack. This is called downthrust. One example would be the RR Griffon-engined version of the Supermarine Spitfire: When the new engine was installed, its lower thrust line required 2° more downthrust.

This is one of the few topics where the English version of Wikipedia stays schtum; only the German version has an article on it (Motorzug and Motorsturz).


How to request to fly on a flight level, different from the direction, according to the charts?

Say you are flying on a route that requires an even level, but you would like an odd level such as FL350. The phraseology to use would be

  Request FL350

The rest is up to ATC. Depending on local agreements and the current situation, we may be able to grant you the level right away, maybe we need to pick up the phone and talk to downstream sectors or maybe we can't offer the level at all. In any case, there is no harm in asking.

Regarding the part of your question that mentions weather, if you are requesting a level change because of extreme weather (such as moderate/severe turbulence or icing), state so in your request. We will then handle your request with higher priority, and you are more likely to get the different level.

  Request FL350 due to moderate icing


Why would the propeller of a lightsport plane or ultralight w/ Rotax engine be connected to the engine through a clutch, and not turn at low rpm?

Centrifugal clutches are mainly used to provide a compliant connection between the engine and prop to absorb power pulse peaks, as well as allow the engine to be automatically disconnected from the drive system at idle.

The big bugaboo of reduction drives over the years has always been torsional resonance resulting from the flywheel - the prop - being driven through a springy drive path by strong pulsating power impulses.  At RPMs where the pulse/feedback frequency matches the natural frequency of the drive system/prop, you get massive resonant torsional vibration, which at minimum is unpleasant and at maximum can trash the gear train.

Over years various attempts have been made to tame this phenomenon in a practical way.  It's not actually a good idea to use a centrifugal clutch in a normal aircraft.  If the engine quits, the prop can freewheel and this turns it into a very powerful airbrake. It's also a reliability issue, being a friction device in a critical power path.

That said, a coupling that has been used with some success, and even certified at one time, was the Flexidyne Dry Fluid Coupling, which works like a centrifugal clutch but uses steel shot encasing a wavy plate in the housing to act a bit like a fluid torque converter.  The FAA certified Molt Aerocar used a Flexidyne to connect the Lycoming to the prop down a long drive shaft (which suffers from the same kind of torsional resonance problems).  Problem is, Flexidynes get really hot, and you still have the windmilling problem (Molt Taylor used the Flexidyne in several of his homebuilt concepts but he never really addressed the freewheeling prop issue) and a propeller brake might be in order if you want to be able to glide (or a feathering or folding prop).

You see centrifugal clutches used in paramotors, mostly because it allows the motor to be running at idle without the prop turning, a handy feature for a paramotor.  I wouldn't be surprised if the Dragonfly's engine is actually using a Flexidyne instead of a friction clutch.

The most common compliant coupling between motor and prop however, is rubber.  Most commonly a rubber drive belt system, used everywhere on ultralights and some automotive aircraft conversions.  Or as successfully used by Rotax, a rubber coupling in the gearbox itself. Rotax, after a lot of effort, was able to create a rubber drive isolator that would be effective in a given engine's operating range.  This would have taken a massive engineering effort over the years to perfect.


How do different RPM–MAP settings affect range?

The advantages of oversquare (MAP > RPM/10) are:

  less vibration, noise, heat, and wear
  longer engine life as a result of this
  much less noise emitted from the engine/propeller
  more efficient cylinder charging and better combustion, gives lower fuel consumption if leaned properly
  less power lost to friction inside the engine

  — Source

Since there are fewer loses to friction and high propeller RPM, the same fuel flow will yield slightly faster flight, and thereby range.

Another article from AVweb that discusses the topic: Why "Over Square" Is Good


What does "CC (Charlie Charlie)" mean when pilots reply to ATC?

Short answer

This wording comes from the common meaning of letter C to be Correct/Yes, early standardized and used at sea since 1857. Under the Commercial Code of Signals (1857-1902), the C flag, in addition of representing the letter itself, had the meaning of Yes/Affirmative. This code has been improved and extended into the International Code of Signals (ICS). While the visual representation changed, the meaning was preserved.

Today's version of the C flag (previous version)

From the 2003 ICS:

  Signals for flags, radiotelephony, and radiotelegraphy transmissions.
  C: Affirmative—YES or “The significance of the previous group should
  be read in the affirmative”.

The pilots you heard were saying affirmative.

Longer answer

Codes have their origin in the need to abbreviate everything at a time the communication channels were limited, as for nautical flags, Chappe, Morse, Aldis, etc. Nineteenth and early twentieth centuries saw appearance of codes (flags, lights, telegraphy, Q, X and Z) in order to federate many isolated practices, in particular in commercial telegraphy (Marconi) and railroads. Codes have many resemblances as they have borrowed good practices and common usages from each others.

In radio communications, letter C has been early used in consistence with the ICS, to mean correct, like when acknowledging a readback with a single C, meaning this is a correct readback.

Example

Discovered by @ymb1, this accident report includes a transcription of the pilot (CA) controller (MA) exchange:

  CA: Roger, we will appreciate it if you can alert, er,
  fire, er, er, er.
  MA: Do you request a full emergency please? A full emergency?
  CA: Affirmative, that's Charlie Charlie
  MA: Roger, I declare a full emergency.

later:

  MA: Confirm runway one four?
  CA: Charlie Charlie.

And this other document, still from @ymb1:

  Do you have ATIS information Delta?
  Charlie Charlie we have Delta.

...

  Ok our stand 41 AF028.
  Understand B 41.
  Charlie, charlie.

Details

Charlie-Charlie is a fancy substitution for a standard affirmative and accepted non-standard words roger and wilco.

Standard phraseology is meant to prevent confusion, and has been improved after incidents/accidents where the communication between parties played a role. In a conversation listed above, we can imagine how information can be  easily misunderstood:

  Do you have ATIS information Delta?
  Charlie Charlie we have Delta.

ATCO are not required to know the ICS, though in many countries, an important part of civil aviation ATCO have had a military career, and are likely to know the meaning of letter C in many codes.

More

More on signals, and how to use flags: ICS, US edition, revised 2003.
More on codes and abbreviations: Origin Of Ham Speak -  Fact, Legends And Myths (AC6V)


Should you sump fuel tanks when the fuel system is below freezing?

OK, I sat on my hands for a while, so now I'll stick my head in the lion's mouth.

You should absolutely sump your tanks every time you go flying as part of a routine preflight inspection, whether you've taken on fuel or not, whether the aircraft has been hangared or out on the ramp, and even if it's below freezing.
Water isn't the only thing you're looking for (misfueling happens - also bits of fuel tank sealant, rubber from a rotting bladder, dirt that made it past the fueling truck's filters, etc. - you want to find these things!)

Ideally if it's below freezing you should also pre-heat your aircraft so the engine, instruments, and fuel are above freezing when you're preflighting (which is generally accomplished by sticking the plane in a heated hangar), but sometimes that's not an option and you make do.

Why should you sump the tanks if it's below freezing?

Well like I said above, water isn't the only thing we're looking for - and all those concerns still hold valid no matter what the temperature is. Water is the one that people seem to come up with as a reason for not sumping when it's below freezing though, so let's talk about water:

There are five general ways water can manifest itself in your (Avgas) fuel system:

Liquid Water
If it's not been below freezing (or it's really sunny and your fuel tanks have acted like an oven) water may be liquid, waiting for you at the sump drain just like on a warm summer day. You'll drain it out and go on about your business.
Slush (ice crystals suspended in the fuel)
If it's below freezing you may have suspended ice crystals or slush in the fuel (particularly if you just took on fuel). This will look "cloudy" when you drain it from the sump and it's a good indication that today is not a good day to fly: you may have a LOT of water in the fuel, and you need to need to deal with it (warm the plane up and drain off the water, and figure out how so much of it got in there in the first place).
(There is a chance that slush could jam your fuel drain open, in which case your fuel tank will empty itself onto the ramp with great rapidity.)
Little bits of ice
Little drops of water can freeze into little bits of ice, which are often just too big to come out of the fuel sump drain, but just small enough to lodge in it and keep it from closing (which, again, will cause your tank to empty itself onto the ramp with great rapidity. This is also an indication that today is not a good day to fly).
BIG bits of ice over the sump drain
Liquid water will flow to the lowest point in the fuel system (the drains). If it's below freezing it will freeze there, potentially blocking the sump drain.
You'll notice this condition because the sump valve may feel stiff, your tank may not drain, or it will drain very slowly, possibly with water in the fuel.
This is a good indication that you shouldn't fly until you figure out what the cause of the problem is (it could be ice, it could be a defective valve, or it could be a bunch of other things, but until you know you want to stay on the ground).
Hidden Ice (big bits of ice away from the sump drain)
This is perhaps the most insidious: Ice that's not near the sump, and doesn't block or jam anything.  Hopefully you'll spot this sitting at the bottom of your tank when you look in to check the fuel level (you do visually check your fuel level, right?), but you probably won't notice anything out of the ordinary when you sump the tank.

(There are of course other ways water can hide out in the system besides the fuel tanks, but these are where you're most likely to find it.)

The most likely "bad thing" to happen to you in any of those scenarios is that your fuel sump will be jammed open by ice. This means you'll spill a tank's worth of avgas on the ground, and you'll have to call your airport's spill cleanup/emergency number and let them know.
That emergency is on the ground, and it may be a little embarrassing to have to explain to the spill cleanup folks, but it's better than the other possibilities.

The Bad Things that can happen to you in the air if you go flying with undetected ice/water in the fuel are far worse: The ice could melt and your engine could start trying to burn water, which doesn't ignite very well.

Check out Gene Benson's "Why Did They Do That? - Volume 2" presentation, starting at slide #7 for one example of how things can go catastrophically wrong if you neglect to sump your tanks (or ignore the warning signs when you do).


What was the takeoff run distance of a Fw 200 Condor bomber/transport?

Unfortunately i could not find this information for the basic variants, but for the Fw200F an Focke Wulf document from 1943 states following

on a paved runway, 4x 323R engines on standard start power

********** (deleted / see graph)

on max power

   ********** (deleted / see graph)

EDIT:


How would a detachable cabin module work?

You are right, this patent looks like it will not work in reality.

Fuselages have to carry two primary loads:

Pressurisation loads, which cause uniform tension in lengthwise and circumferential direction, and
bending loads from inertial and control surface loads, which create both tension and compression loads in lengthwise direction, plus some shear.

Reducing the height of the fuselage will drive up the strain from the bending loads, so more material is needed to transmit them. Also, the bottom of the passenger compartment and especially the corners at the lower edges will experience much higher loads than a cylindrical fuselage ever would under pressurization. Again, to make this work needs a much beefier structure.

The loads could be kept the same if the passenger compartment is tightly bolted to the remaining aircraft structure such that the combination of "flatbed" fuselage and passenger compartment can be considered as a contiguous structure, but this would need redundancy in the connections and would make fitting the passenger compartment non-trivial. Airbus is arguing in this direction, but I wonder how much time can be saved and how much maintenance time is added if the primary structure of the fuselage is torn apart and re-joined at every stop. Note that you not only need to connect the parts at each end, but to transfer pressurization loads you need to bolt them together along the full length of the passenger cabin as well.

Today's airliners are already designed to survive partial depressurization, such that the lower fuselage is depressurized without the pressure loads in the upper part causing damage. Therefore, the fact that both parts can be split and can depressurize independently of each other does not add additional load cases. However, the structure today is dimensioned to sustain those loads only for a short time. Pressurizing only the passenger compartment or not joining the parts along the full length for every flight will need a much stronger structure than what is used today, so the weight impact of a simpler way of joining both parts will most likely result in an economically unattractive outcome.

I did not go into detailed calculations, but I strongly suspect that this idea will not be adopted by airlines. Besides the structural impact, such a way of loading passengers would complicate logistics, since a fitting passenger container plus facilities for mounting it on the aircraft must be available at the departure and destination airfields.

Lastly, proposals like this are not exactly new, which is why the first claim extends over 73 lines to be narrow enough to not conflict with earlier patents or publications. If there had been some value in this idea, we would had seen it being adopted long ago.

In helicopters, however, which fly at altitudes where no pressurization of the passenger compartment is needed, this idea has been tried out before. See below a picture of the Sikorsky S-64 Skycrane carrying a container (picture source) in which passengers could be carried.


How can I determine whether or not an airport has an ATIS?

The frequency for and class of the ATIS is on the VFR Sectional Chart right where you have indicated. It will also be listed in the US Chart Supplement under Weather Data Sources. The ATIS Code will never be listed as it is a function of the ATIS itself. And, it changes over time.
The left side of that section of your VFR Navigation Log is meant to be filled out shortly before takeoff. The right side of that section of your VFR Navigation Log is meant to be filled out shortly before arrival. It is helpful to have the information beforehand in your preflight planning in order to make a go/no-go decision. But, it’s primary purpose is to inform the pilot of current takeoff conditions at the time of departure and arrival. At a controlled airfield, you will be required to confirm you have the most current ATIS information by relaying the ATIS Code to ATC. That ATIS code is acquired either by listening to the ATIS over the ATIS frequency, over your cell phone at the phone number given in the US Chart Supplement, or electronically. The ATIS Code changes each time the information on the ATIS is updated. For a Class D, E, or G airport, in most cases, that is once every hour around the 45-55 minute mark. It can be more frequent for a more advanced, automated digital, non-automated, or human recorded ATIS at a Class B, C or large D airfield.
By the way, many air traffic controllers I have talked to have said that they must hear the ATIS Code either at the beginning, right after your tail number, or at the end, as the last piece of information of your initial transmission/radio call. But, I do not have any citations or references for this. Maybe another poster can provide one.


Why do some aircraft have to have the landing gear pinned prior to towing?

The most direct answer is that gear pins are installed to prevent accidental retracting during towing. I'm not typed on the Phenom, but the landing gear actuators are most likely hydraulic. Even if they are electric, the airplane is expected not to have any form of power established during towing, making accidental retraction more possible, even if the gear is held in the down position by locks, not its actuators.

The requirement to install the gear pins is not related to the trailing link design. No matter what the design was, that requirement would be there for each gear.

This requirement is ubiquitous on larger aircraft. During airline operations, I have had an aircraft towed over to me many times. I have never seen a plane in tow, at least at my company, that did not have the gear pins installed during towing.


What is the difference between "Bay" and "Stand"?

The correct terminology for a place where aircraft park is stand or aircraft stand, where bay or parking bay is colloquial.

The official definition from the ICAO ANNEX 14/I Aerodromes is:

  Aircraft stand. A designated area on an apron intended to be used for parking an aircraft.

This can be either a stand at a gate or a remote parking stand.

The correct use of the word bay is for a holding bay as defined in ICAO ANNEX 14/I Aerodromes as:

  Holding bay. A defined area where aircraft can be held, or bypassed, to facilitate efficient surface movement of aircraft.

So you use the term stand for an area where aircraft park (i.e. shut down engines, load/unload cargo, (dis-)embark passengers, etc.) and you use the term bay for an area where an aircraft temporarily holds (typically with engines running).

There are some sources using the term bay for parking, but I would consider all of them more informal than the official ICAO definitions:

The ENAV (company providing air traffic control services in Italy) writes (emphasis mine):

  [...] which guides it right up to the parking bay.

on the English version of their website, but this could also be a wrong translation from the Italian original.
The Thales Group (French aerospace company) writes (emphasis mine):

  Tower ensures smooth and seamless aircraft control between TMA boundary and the parking bay.

which again might be result of incorrect terminology used by the translator.
This article by Qantas suggests that the term is actually used by Australian ATCs (emphasis mine):

  PILOT: “Qantas 635...we will arrive on blocks at 1500. Have 2 UMs, 2 WCHRs, 1 will need assistance to a taxi. Request a parking bay please.”

  MOCO: “Copy that Qantas 635. 2 UMs, 2 WCHRs. You are for parking bay 26...2...6. See you on the ground Qantas MEL.

The CAAS (Civil Aviation Authority of Singapore) is also using the term (emphasis mine):

  the aircraft was also assigned the shortest possible route from the runway to the parking bay to minimise fuel consumption.

Related:

What is the difference between a Stand and Gate in Airports? How do they differ ?
What are the correct names of the parking spaces for turn-around?


Is it allowed and safe to carry a passenger / non-pilot in the front seat of a small general aviation airplane?

There should be no problem in general with flying with a passenger in a front row seat in a GA flight, as long as the aircraft is certified for single-pilot operations. You'd want to check your national regulations to be certain, but I have a hard time imagining that it would be prohibited as long as you're allowed to carry passengers in the first place. In general, it's normal practice in small airplanes for passengers to fly up front.

However, especially for anyone not used to a cockpit environment, you would definitely want to brief them on expected behavior before beginning the flight, in addition to any pre-flight briefing required by legislation. Even if such legislation only require briefing before a commercial flight, it might be good, and put your passenger more at ease, to do something similar before a non-commercial flight as well. (How to get out of the seat belt, how to exit the aircraft, where the airsickness bag is, ...)

None of this needs to be complex stuff; what I have in mind here is mostly things like keep your feet clear of the pedals, keep your legs clear of the yoke, don't touch any of the controls unless told to, and similar. As Jamiec points out in their answer, it's very unlikely that someone not used to light aircraft would know what the rows of instruments, switches and controls are about, so a quick "fly safely in the cockpit" style briefing would absolutely be appropriate in addition to a general pre-flight briefing.

For a (somewhat humorous) example of what I have in mind, you might want to check out Preflight Announcement, Maule on Youtube.

Especially since this is someone you know, and you'd therefore presumably be able to gauge their reactions more easily than if they were a stranger, don't be afraid to sprinkle some appropriate humor into the briefing. For one example, I've heard of the airsickness bag being referred to as the rollercoaster bag.

It may also help put your passenger at ease if you specifically tell them what you're about to do before you do something unusual or non-obvious, such as the engine runup and magneto check. Particularly with non-pilot passengers, you don't want to get technical; something like "I'll do a few engine tests to make sure it's running smoothly before we take off" is more meaningful to them than "I'll bring the engine to 2391 RPM while holding position, and then check the magnetos and carb heat before reporting ready to Tower". Certainly when flying with another pilot you might just say "mag check", or even nothing at all (they'd probably be expecting you to do it).

Especially if your friend is an adult or an able teenager (but probably not for people much younger than that), do consider the possibility of enlisting their help with simple tasks during the flight. Regulations permitting and of course assuming that you as the pilot in command feel comfortable with it, you could even let your friend take the controls for a while, as long as you're able to take over if necessary and you're able to ensure that nothing untoward happens. If nothing else, they can definitely help look out for and call out nearby traffic while hopefully enjoying the view.

You could also show your friend how to use the radio to contact ATC in an emergency, and at least the very basics of keeping the airplane in the air (things like mostly straight and level flight; shallow turns, possibly without rudder; climb and descent; stall indication and response; where the throttle is and how to operate it; and possibly the IDENT function on the transponder). In the unlikely event that something were to happen to you, while not a guarantee, doing so would greatly increase the odds of both of you eventually making it out of the airplane in one piece. I have written a much more in-depth answer about this from the passenger's perspective which you might find informative. It's possible that there are even courses specifically tailored toward GA passengers in your locale, which would/could cover such topics; if not, any instructor worth their salt should be able to put something together easily enough for a given airplane type. If this is someone you expect to fly with often, that might be money well spent for both of you.


Why does the F-22's wing give it such great maneuverability?

The wing design is different between F-16 and F-22 (which is similar to YF-23) because the requirements were different.

The wing of F-22 (and that of F-23) were designed with stealth in mind, with the wing (and control surface) edges parallel to each other. There was no such design requirement in case of F16.

F-16 is a highly maneuverable aircraft in its own right. However, there are some reasons the F-22 is more maneuverable (i.e. it is super maneuverable) compared to the F-16, most of which are unrelated to wing design.

In general, lesser the wing loading, higher the performance. F22 has a lesser wing loading compared to F-16 (377 kg/m² vs 431 kg/m²). Though this figure will vary depending on various conditions, the F-22 has a lower value, helping in maneuverability.
The F22 has thrust vectoring, which basically acts to increase the control authority and also helps in controlling in high alpha region where the conventional controls would've become unusable.
The F22 is maneuverable in the post-stall region, something the F-16 is not capable of. This helps the F-22 in performing maneuvers like the Cobra and Kulbit, which is not possible in F-16.

As a side note, the F-16 VISTA technology demonstrator (which had thrust vectoring) is considered super-maneuverable on par with THE F-22, though it had the same wing.


Does a Second In Command have to be landing and instrument current like a Pilot In Command does?

FAA

This is a compilation of what I could find relevant to the question. Feel free to come up with corrections if I missed anything (I'm an EASA FCL guy)

Co-pilot Landing Currency:

Part 61: 3 takeoff/landings in previous 12 months (61.55)
Part 135: no requirements other than those in part 61 (above)
Part 121: 3 takeoff/landings in previous 90 days (121.439)

Co-pilot Instrument Currency:

Part 61: no requirements for SIC
Part 135: 135.245 requires that SIC's must meet part 61 PIC instrument currency requirements in 61.57(c) (see below)
Part 121: recurrent flight training every 12 months, including at least 1 ILS approach to minimums

Following is the list of relevant FARs :

§ 61.55 Second-in-command qualifications

  (b) Except as provided in paragraph (d) of this section, no person may serve as a second in
  command of an aircraft type certificated for more than one required
  pilot flight crewmember or in operations requiring a second in command
  unless that person has within the previous 12 calendar months:
  (2)
  Except as provided in paragraph (e) of this section, performed and
  logged pilot time in the type of aircraft or in a flight simulator
  that represents the type of aircraft for which second-in-command
  privileges are requested, which includes --
  (i) Three takeoffs and
  three landings to a full stop as the sole manipulator of the flight
  controls;

  (d) This section does not apply to a person who is:[...operating part
  121,125,135...]

  (e) The holder of a commercial or airline transport
  pilot certificate with the appropriate category and class rating is
  not required to meet the requirements of paragraph (b)(2) of this
  section, provided the pilot: [... is not carrying paying
  passengers...]

§ 61.57 Recent flight experience: Pilot in command.

  (a) General experience.

  (1) Except as provided in paragraph (e) of this section, no person may
  act as a pilot in command of an aircraft carrying passengers or of an
  aircraft certificated for more than one pilot flight crewmember unless
  that person has made at least three takeoffs and three landings within
  the preceding 90 days, [...]

  (c) Instrument experience.

  Except as provided in paragraph (e) of this section, no person may act
  as pilot in command under IFR or in weather conditions less than the
  minimums prescribed for VFR, unless within the preceding 6 calendar
  months, that person has: [...6 approaches, holdings, intercepting
  &tracking course...]

§ 135.245 Second in command qualifications

  (a) [...] no certificate holder may use any person, nor may any person
  serve, as second in command of an aircraft unless that person holds at
  least a commercial pilot certificate with appropriate category and
  class ratings and an instrument rating. For flight under IFR, that
  person must meet the recent instrument experience requirements of part
  61 of this chapter.

This is an excerpt from an FAA Legal Interpretation concerning 135.245:

  Next, unlike a PIC, an SIC's qualification to operate an aircraft
  under IFR in part 135 service is not dependent on compliance with §
  135.297.  Rather, § 135.245 sets the qualifications for pilots serving as SIC in part 135 operations.  It states that a pilot must meet the
  instrument experience requirements of part 61 to serve as SIC in
  flight under IFR.  Section 61.57(c) sets out the recent instrument
  flight experience requirements which include, among other things, six
  instrument approaches within the previous six months.  See Legal
  Interpretation to Gerald Naekel, from Donald P. Byrne, Assistant Chief
  Counsel Regulations and Enforcement Division (June 18, 1991) (noting
  that although the section title refers to pilots in command, the
  instrument recency requirements of that section apply to SICs).

§ 135.247 Pilot qualifications: Recent experience.

  (a) No certificate holder may use any person, nor may any person
  serve, as pilot in command of an aircraft carrying passengers unless,
  within the preceding 90 days, that person has—

  (1) Made three takeoffs and three landings as the sole manipulator of
  the flight controls in an aircraft of the same category and class and,
  if a type rating is required, of the same type in which that person is
  to serve; or [...]

§ Part 121.433 Training required

  (c)Recurrent training. (1) No certificate holder may use any person
  nor may any person serve as a required crewmember on an airplane
  unless, within the preceding 12 calendar months --  (i) For flight
  crewmembers, he has satisfactorily completed recurrent ground and
  flight training for that airplane and crewmember position and a flight
  check as applicable;

§ Part 121.439 Pilot qualifications: Recent experience.

  (a) No certificate holder may use any person nor may any person serve
  as a required pilot flight crewmember, unless within the preceding 90
  days, that person has made at least three takeoffs and landings in the
  type airplane in which that person is to serve.

EASA

FCL is very clear about it: PIC and co-pilot both need to be landing current. If holding an IR rating then specific night currency is not required. No instrument currency is required as long as the IR is valid.

FCL.060 Recent experience

  (b) Aeroplanes, helicopters, powered-lift, airships and sailplanes. A
  pilot shall not operate an aircraft in commercial air  transport or
  carrying passengers:

  (1) as PIC or co-pilot unless he/she has carried out, in the preceding
  90 days, at least 3 take-offs, approaches and  landings in an aircraft
  of the same type or class or an FFS representing that type or class.
  The 3 take-offs and landings shall be performed in either multi-pilot
  or single-pilot operations, depending on the privileges held by the
  pilot; and

  (2) as PIC at night unless he/she:

    (i) has carried out in the preceding 90 days at least 1 take-off,
    approach and landing at night as a pilot flying in an aircraft of the
    same type or class or an FFS representing that type or class; or

    (ii) holds an IR;


When does a turbine need to go to maintenance?

This is a very broad question, but if we limit ourselves to just high bypass turbofans, such as the CFM56 or LEAP-1A used on the A320, and limit "maintenance" to mean major maintenance that requires the engine to be removed from the wing, then the primary driver is typically the total number of flights.  Depending on the engine, it would be removed from the wing for a complete teardown, inspection, and rebuild perhaps every 5,000 - 10,000 flights (typical lifetime of the engine could be between 30,000 and 50,000 flights). Many major components are limited by low cycle fatigue (LCF) driven by thermal stress, so the cold-hot-cold cycle of a flight is what drives the maintence interval, more so than the total flight hours.  i.e. a 1 hour flight and a 12 hour flight are pretty similar in how much they wear out the components.


Neither. The best one would something between 2 and 3. The continuation of the wire should cross the intersection between the middle lines of the spar and compression tube.

In structures with two-force members, such as trusses and combinations of rods and beams with wires, the members are intended to work primarily in tension/compression. To achieve this, the middle lines of the cross sections of all members at a joint should intersect in a single point. If they don't, some of the members will have to carry additional loads such as bending or torsion moments.

Problems due to eccentricity at joints often show up as fatigue problems: even if the aircraft structure passes all static tests, the stresses due to the additional bending moment make the structure fail much earlier than it would have if correctly assembled/designed.


Why doesn't Ketchikan, AK have a control tower?

A tower can only control what it can see, visually or with radar. The traffic in that area is at low altitude and landing or taking off many places that are not the central airport, much is VFR and not inside the space of a class D tower.


Elliptical wing planform and elliptical lift distribution

Lift force over the wing is said to be of elliptical distribution if the lift per span ($L'$) along the wing span is of the following:

$$L'(y) = \rho_\infty V_\infty \Gamma_0 \sqrt{1-(\frac{2y}{b})^2}$$

where $\rho_\infty$ is density of the airflow, $V_\infty$ is the free-stream airspeed, $b$ is length of wing span, $y$ is lateral coordinate along the wing (0 being wing root), and $\Gamma_0$ is the circulation at wing root.

The above is essentially an equation of an ellipse, and hence the name elliptical lift distribution.

In low Mach flight, it can be theoretically demonstrated that an elliptical lift distribution produces the least induced drag for a given flat span. Induced drag of a lifting surface in incompressible flow can be expressed as (Ref Anderson, Fundamentals of Aerodynamics):

$$C_{D_i}=\frac{C_L}{\pi e A}$$

where $C_L$ is the lift coefficient, $A$ is aspect ratio and $e$ is the span efficiency factor.

For a flat span, $e$ must be smaller or equal to 1, and it's only equal to 1 when the lifting surface has an elliptical lift distribution.

When the wing has zero twist, an elliptical planform produces an elliptical lift distribution. However, elliptical lift distribution can also be coaxed by judiciously twisting the wing for a planform that is not geometrically elliptical.

Addendum on non-flat span:

In the case where the span is not flat, either because it has dihedral or is curved, it has been theoretically demonstrated that a non-flat span can achieve lower induced drag than a flat wing of equal projected span. This forms the theoretical basis behind winglets, end plates, spiroids, etc.

However, if we compare the non-flat wing to a flat wing whose length is that of the unfurled non-flat wing, the flat wing always has lower induced drag. That is, if there is no limit on the wing span length, elongating it is always better from an induced drag perspective.

Below is a graph comparing the induced drag of an optimal non-flat (circularly cambered wing) wing to that of an elliptically loaded flat wing. A value of 1 indicates no change. A value greater than 1 indicates more induced drag and a value less than 1 indicates less. $\beta$ is the span camber factor.

Data and figure compiled from https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19630006412.pdf


Why does NASA's B-52 008 have a smoking engine in this photograph?

@Adam is right. The aircraft, NB-52B has smoke generator installed to assist in tracking.

A smoke generator has been installed on the left wing of the Boeing NB-52B Stratofortress mothership to assist in tracking the airplane.

Its use during the test of X-38 is detailed here:

Outside I could see the white trail from the smoke generator in the number-2 engine nacelle of the NB-52B approaching from the east
... I aimed my telephoto nearly directly up at the tip of the smoke trail.

As the same aircraft was used during the X-43 tests, it certainly served the same purpose.