Can an aircraft continue flying and land safely following an engine failure?

The answer to your question strongly depends on what kind of airplane you're talking about (in particular, what set of rules it was certificated under), as well as the phase of flight you are in (takeoff vs. cruise vs. approach/landing) and whether you are in a jet or a (turbine or piston) propeller aircraft.  (I'm going to exclude single-engine airplanes from this discussion, as well.)

Cruise Flight

In general, an engine failure in cruise flight is a manageable emergency unless you are in extremely high terrain in a light twin or some other corner case.  The general procedure is to "drift down" in a slow-ish descent to your single-engine cruise altitude -- if you don't already have a driftdown airspeed worked out, you can use Vyse as a substitute to get a slow driftdown -- and then divert to a nearby suitable airport to get the busted engine looked at, as you'll be flying lower and less fuel-efficiently as a result.

Takeoff

Takeoff is the most troublesome time for an engine failure to happen, bar none: you are at high gross weight and don't have altitude under you to turn into airspeed and landing options.  What you want to do is get to the pattern altitude, fly a pattern, and land in a reasonably quick, but orderly fashion -- you don't need to ultra-hurry things even if you have an engine on fire, but you do want to get back on the ground in a reasonable timeframe to get things looked at.

Light Twins (cabin class, commuter, pre-FAR 25 airliners)

These aircraft, unfortunately, struggle in single-engine situations on the best of days, as the certification requirements for single-engine performance in FAR 23 are minimal at best.  The common adage you will hear about light twins, even, is "the second engine will carry you to the scene of the crash" -- it is possible for a light twin to be type certificated with nil or negative worst case single-engine climb performance in the case of an engine failure at or shortly after takeoff.

Business Jets (certificated under FAR 23)

Corporate or business-type light jet aircraft (Citations, Gulfstreams, LearJets, Beechjets, etal) and their turboprop counterparts (such as KingAirs), while often certificated under Part 23, will generally have superior single-engine performance to light twins, although this is by no means guaranteed.  You'll likely get up into the pattern and be able to make a reasonably normal single-engine landing, barring any aggravating factors at least; this is because even the smallest turbine engines are large enough that the aircraft will have some degree of excess thrust as a twin, leaving it with a thrust reserve in a single engine situation.  These aircraft are also flown by pilots with type ratings and a CPL or ATPL, which means they will be more familiar with the performance of that specific aircraft and any aircraft-specific engine-out procedures needed to eke out maximum single-engine climb rates.

Twin-Engine Airliners (transport class twin turboprops and twin jets certified under FAR 25)

The FAR 25 requirements for engine-out takeoff performance are much more stringent than FAR 23, and practically guarantee that the aircraft is capable of positive climb in a V1 cut (engine failure right after decision speed) at maximum takeoff weight.  In addition, V1 cuts are a classic airline training scenario that every airline flight crew on the planet runs in the sim on a regular basis (I wouldn't be surprised if a V1 cut came up every few sim sessions or so, if not every sim session).

In a practical sense, this means that unless the aircraft is overloaded or is suffering from something beyond a simple engine failure (I'll talk about that later), an airline flight crew will handle engine failure on takeoff in an airliner as a routine event.

3 and 4 engine airliners

A single engine failure on a three or four engine aircraft is by no means critical, especially on three- and four-engined jet transports.  This doesn't mean that 747 crews don't practice V1 cuts any longer, though!

Props vs Jets

Engine failure in a jet, whether it be a T-37 or an A380, is simple: you put appropriate rudder in, ID which engine died (between your instruments and "dead foot, dead engine", you should have enough data to go on), add power as needed on the working engine (say, if you are doing an assumed/FLEX temp takeoff), and kill the dead engine, then run the rest of the checklist at a leisurely pace now that safe flight is more-or-less assured.

Propeller aircraft are a bit more complicated though in that you need to feather the dead engine's propeller to keep it from dragging the airplane down -- older constant-speed prop designs such as those on warbirds and piston-engine airliners had FEATHER buttons for this job, one per engine; newer aircraft with constant-speed props have a gate on either the power or the condition levers that serves in place of the feathering button.  You also have more levers to manipulate when adding power to the working engine(s) and killing the dead engine, and may have more difficulty figuring out which engine died without positive flight control responses (I can only imagine how baffling a center engine failure on a Trislander would be!).

As a result of the critical nature of the feathering process, modern (and even some not-so-modern) transport-class (and some other) propeller aircraft have an autofeather or NTS (Negative Torque Sensing) system that will automatically drive the blades of a propeller towards (or even all the way to) the feathered position if it is armed and senses that the propeller is trying to drive the engine.  However, feathering the propeller on an engine that isn't shut down is also a bad idea as it causes the propeller and engine to overspeed due to the airloads the engine was driving going away.

Of course, if you are in a light twin with fixed-pitch propellers, none of this feathering talk applies.  Be prepared for the unexpected emission of foul language during engine-out procedures, though!

Approach/Landing

An engine failure during the early phases of approach is generally unproblematic -- it's similar to a failure at cruise, just minus the driftdown.  However, an engine failure on short final can be troublesome due to the high workload of an approach, combined with the thrust asymmetry induced during a full-power, single-engine go-around.  Prompt rudder inputs are essential in order to maintain aircraft track and control during such a maneuver, and engine failure checklists are best deferred until stable flight.

Engine failures during the landing roll are rare, by the way, and typically a non-event.

Worse than Engine Failure

There are engine damage scenarios that represent a greater hazard to the aircraft than a simple engine failure, or even a fire in an airliner engine.  These fall into three categories: uncontained turbine engine failures, engine detachments, and propeller failures.

Uncontained Turbine Engine Failure

Turbine engine failures are divided into two types: "contained" failures where the busted parts fly out the tailpipe, and "uncontained" failures where a turbine or compressor disk basically explodes radially, sending parts flying in a 360° radius around the engine; at this point, further damage is a game of aerial roulette, and can range from a few holes in the cowl to near-catastrophic levels of damage that pose a threat to the entire aircraft.

Engine Detachment

Engines, even when pod-mounted, rarely fall off airplanes, and much of the time when they do, they depart quietly, a yanked-back thrust lever and nil engine readings the only signs of their absence visible to the flight crew.  However, a detached engine is somewhat unpredictable in its behavior, and can strike another engine on the same wing or another part of the aircraft, leading to further damage that can compromise aircraft systems or impair the operation of that neighboring engine to the point where the thrust asymmetry becomes uncontrollable.  Nacelle-mounted engines are actually worse in this regard -- a nacelle-mounted engine departing its nacelle leaves behind a big, draggy air scoop that will severely hamper single-engine flying, and on a light twin, this is simply insult atop injury as you have gone from "barely making it to your site of choice" to "we need to pick the nearest open spot NOW because we're trying to fall out of the sky in a hurry"

Propeller failure

Propellers do not fail nearly as often as engines do, but when a propeller fails in flight, the results can be catastrophic; an overspeeding prop can fly apart violently or rip its mated engine apart while producing asymmetric forces that have the potential to overwhelm all flight control, while the inability to feather a failed engine's propeller turns it into a drag brake on that side of the aircraft, crippling any attempt to obtain reasonable single-engine climb performance.


How the antenna on the B737 Max fuselage doesn't disrupt the airflow?

Anything new attached to the outside of the airplane will change the airflow in someway; that is unavoidable.

The only question is if it will disrupt the airflow in a way that has a significant negative impact on the plane.

You'll recognize that the antenna is installed very close to the CG, so the new air resistance has virtually no pitching moment.

It is far from any control surface, so those all work the same.

The increased air resistance affects fuel economy a very tiny amount, but paying customers have enough preference for inflight wifi that its worth it.


Why isn't there a single best airfoil for subsonic flight?

For the same reason why we do not have one single type of aircraft flying all commercial and military missions worldwide: flight has many variables, and there is no single optimum solution.

First off, you mention transonic flight in your question, which usually involves sonic flow at over at least part of the airfoil, which significantly alters the desired properties of the airfoil. To follow with this example, have a look at supercritical airfoils. They exhibit good qualities for their typical flight regime, albeit at substantial development and manufacture cost. A simpler NACA airfoil would be more cost-effective for applications that do not require high-subsonic cruise efficiency as one of their main points.

Additionally, there are more specific situations, like flying wings, that usually use reflex camber to deal with the lack of horizontal stabilizer. Again, this modification is rendered into pointless weight and cost if used outside this particular scenario.

Now, to specifically address your Lift-to-Drag requirement: that is simply not a good way to decide "the best airfoil for subsonic flight". High efficiency is important for aircraft with a mission that emphasizes endurance. This category is populated by gliders, and is indeed full of highly optimized designs ($C_L / C_d \approx 50$ is not unheard of) with little differences, mostly due to structural considerations.

Now take another subsonic aircraft with an emphasis on endurance: the maritime patrol aircraft, the best known example here is probably the P-3 Orion. A glider airfoil would be terrible because of the need for thickness to accommodate a spar that can carry the engines without breaking under a bad gust. Instead it uses a NACA 0014-1.10 at the root, transitioning to a NACA 0012-1.10 at the tip, meaning the designers had to compromise between two airfoils even within the same wing.


How does the stick pusher prevent an aircraft from stalling?

A simple explanation is that a stick pusher is a:

  ... device that pushes forward on the elevator control system
  whenever the aircraft’s angle of attack reaches the pre-determined
  value, and then ceases to push when the angle of attack falls
  sufficiently.

A detailed explanation is:

  A stick pusher system incorporates both a passive monitoring component
  and an active intervention component that consists of an hydraulic or
  electro-mechanical pusher mechanism. The monitoring component
  constantly evaluates critical flight parameters such as airspeed, load
  factor and flap setting against the aircraft angle of attack. If the
  angle of attack reaches a predetermined value, the intervention
  component of the system is activated and pushes forward on the
  elevator control system until the angle of attack is reduced to an
  acceptable value. The system operates autonomously and without any
  required action by the pilots.

FAA has an advisory circular (AC) for stick pusher training.

For Embraer 145, this video shows a demo of stick shaker, stick pusher and the warning systems.


Does the autopilot attempt to recover from a mechanical failure of a single control surface?

Normal autopilots don't. They expect all systems to work correctly, and in case of  failure of a single control surface they will stubbornly command actions which are no longer possible. For them, thrust is only for controlling the vertical speed, and the application of asymmetric thrust for yaw control is not possible.

There are experimental autopilots which compare the result of their actions with a number of pre-programmed scenarios and select for their next commands the scenario which agrees best with reality. These really do what you assumed, but the specific scenario must have been considered before so the specific control laws are part of the code. Computers small enough to be carried on airplanes became powerful enough to do this in real time maybe 20 to 25 years ago, but I am not aware that regular autopilots of airliners have this capability even today. It is, however, used for unmanned vehicles.


I'm Otto, the aviation.SE Autopilot!

I live in the site's chatroom and do useful-ish things like provide METARs and quote the FARs to people.

In order for me to stay in the chatroom I need people to say nice things about me, so if you wouldn't mind clicking the up-arrow next to my answer I'd really appreciate it!


What regulations apply to flying near blasting areas in Canada?

Blasting areas are not subject to particular regulation, they can be depicted on charts and/or announced by NOTAMs (code for blasting is WH, compliant to ICAO standard).
The blaster operator always ensures the area is clear of traffic prior to firing. The imminent blast may also be announced 4 and 1 minute(s) prior to the operation on 123.2 MHz. In case an aircraft is seen, the blaster operator will also use this frequency to inform the pilot of the blasting operation. See below for details.
It's pilot responsibility to remain clear of these areas:

Source: AIP Canada

Known permanent blasting activities can be depicted on VFR charts and announced by NOTAM until charts can be updated. From AIP Canada:

The “VFR Chart Updating Data” section of the CFS provides a means of
notifying VFR chart users of significant aeronautical information to
update the current VFR aeronautical charts. In this regard,
significant  aeronautical information is considered to be that which
affects the safety of VFR operation, e.g. obstructions, restricted
and advisory areas, blasting operations, cable crossings, and new or
revised control zones. New or  revised information of this nature,
which is required to be depicted on visual charts, is advertised by
NOTAM  until such time as the information can be published in the “VFR
Chart Updating Data” section of the CFS.  Subsequently, the NOTAM is
cancelled.

However temporary or itinerant blasting activities may not be advertised. From the Canadian AIM:

Another  concern  to  low  flying  is  the  blasting  operations
associated with the logging industry. The trajectory of debris  from
the blasting varies with the type of explosives, substance  being
excavated and the canopy of trees, if any. These blasting  activities
may or may not be advertised by NOTAM.

More details are given in the NOTAM Operating Procedures, chapter 5.5.5:

In the Pacific Region, NOTAM are not issued for blasting related to
logging activities under the following circumstances:

If using instantaneous blasting equipment.(The blasters will ensure the area is clear of all air traffic prior to the blast.)

If using a standard 6 minute-fuse and using aeronautical frequency radio. (The blasting operator will make two transmissions on 123.2 MHz
advising of the imminent blast. These transmissions will be at
approximately 4 minutes and 1 minute prior to the estimated blast.
These transmissions will include the geographical location referenced
to prominent landmark and the time to the blast.)

If blasters detect an aircraft in the immediate vicinity of a blast,
they will direct a radio transmission to that aircraft using aircraft
type and colour ("Red and white helicopter, you are over an active
blast site; clear the area immediately.").
Blasters may elect to use both methods for added safety.
A NOTAM will be required if the blast site is within 5 nautical miles
of an aerodrome or if the blaster elects not to use either of the
above procedures. In any case, the NOTAM will have a maximum duration
period of 14 days.

Minimum safe altitudes don't take blast risk into account. From the Canada Air Pilot publication:

"CYA, CYR and known blasting areas are not considered in the
establishment of MSA altitudes. For this reason, it is the pilot’s
responsibility to remain clear of these areas as applicable"

Source: Canada Air Pilot
More: See this discussion: Quarry blasting not regulated for aviation safety purposes.


What is the outer kink on the airbus 340-600?

The outer kink on A340-600 wing is located just outboard of the outboard engine, note trailing edge kink in planform drawing.


Effect of gravity vs airmass on a falling object

This answer assumes that the wind is uniform in direction and speed, from the balloon all the way down to the ground.

The object will impact the ground directly below the balloon, not "upwind" of the balloon.

As the falling object accelerates vertically, the trajectory of the falling object as viewed from the ground reference frame continually becomes more and more perpendicular to the ground.  Yet the horizontal components of airspeed, force, and acceleration are all zero throughout the entire fall, so the falling object remains directly under the balloon.

As viewed from the airmass reference frame, the trajectory of the body is purely vertical, i.e. completely perpendicular to the ground, throughout the fall.

The horizontal component of the object's groundspeed is constant throughout the fall, and equal to the wind speed.

Now imagine simultaneously dropping a low-density object and a high-density object from the balloon.  Both would be directly below the balloon at the moment of impact, but they would impact at different times.

For more, see Force Balance from Wind

Also, note that saying the object will tend to fall straight down relative to the earth, rather than relative to the balloon and the airmass, is essentially saying that the earth is a privileged reference frame, which goes against the laws of physics.


Do airliners adjust altitude for latitude?

(aviationweather.gov) Significant weather chart.

Note the numbers in boxes. They decrease as the latitude increases: 450 → 400 → 350 → 250.

Note: those values change day to day and season to season, they're not fixed.

Those are the tropopause heights. 450 is FL450, i.e., 45,000 feet at a standard altimeter reading.

This figure is very important in flight planning. Jets typically fly around this figure for optimal aircraft/engine performance.

So yes, you're right, the farther you fly from the equator, the lower you should fly. However, the following two statements are incorrect:

I'd expect that the air pressure at the top of the troposphere [be the same regardless of latitude.]

The pressure gradient is still the same. See: Why is the troposphere 8km higher at the equator than the poles?

As the altitude of an airliner increases, the angle of attack [also increases.]

As the altitude increases, so does the speed, to counter the thinner air. Until you end up in a coffin corner.

Also, for high latitude polar flights, an airline can do away with the optimal performance, because the rise in temperature helps keep the fuel from freezing, however I may stand corrected on that.


You can check out this info from the FAA

And the official FAA definition:

  Public use airport is an airport available for use by the general
  public without a requirement for prior approval of the airport owner
  or operator.

It should be noted that 4 airports in the US are considered "High Density" and have special rules about operations during certain times which require approval for use (arrival/departure) despite being public.

  §93.125   Arrival or departure reservation.

  Except between 12 Midnight and 6 a.m. local time, no person may
  operate an aircraft to or from an airport designated as a high density
  traffic airport unless he has received, for that operation, an arrival
  or departure reservation from ATC.

In answer to the question as its now worded,

No, there are public airports that are not federally funded. The airport I currently fly out of KDYL is owned and operated by the local government (Bucks County) and they are responsible for most things that go on there. I am not sure if they have received Federal funding in the past but I will ask around.

There is also such thing as "Privately Owned/Publicly Used" (elsewhere called POPS) airports like Trenton Robbonsville N87. These airports are owned privately, run privately, and generate their own income however you don't need to prior approval to land there and are open to general public use.


In an ATIS broadcast, is the visibility in statute or nautical miles?

The FAA has this handy chart to decode METARs (which are the printed version of the ATIS) and TAFs.

  Prevailing visibility; in U.S., Statute Miles & fractions; above 6
  miles in TAF Plus6SM. (Or, 4-digit minimum visibility in meters and as
  required, lowest value with direction)


What does the ATR72-600 MFD System display look like?

For me, it looks like the first picture is something like a screenshot. It looks real. (A bit blurred and pixelated)

The second one looks like a graphic made in a graphics program. There can be small deviations from the original screen design, because it's only for informational purposes.

The third one is a black/white graphic that is made for printing (in the FCOM). I think it should be showing the real MFD quite close to reality because pilots must see it as in real life. But this saves printer color and has more contrast.

I am pretty sure, the first one is a real screenshot. It shows commonalities with the drawing in the FCOM and it looks real.


What if you don't recognise an aircraft ATC is telling you about?

To add to Dave's answer, if traffic is pointed out to you which you are unfamiliar with, ask for clarification. ATC or FIS will have a good understanding of aircraft types and speeds, especially in radar environments the speed will be available as groundspeed (GS).

  FIS: DELFF, traffic information, 3 o'clock, 4 miles, same altitude, Mooney Bravo, passing right to left.
  PIC: DELFF, unfamiliar with aircraft type.
  FIS: DELFF, traffic is a low wing aircraft, 100kt groundspeed


Double deck vs wide body airliner, why would anyone build a double deck one?

Problems with just making the fuselages wider:

With the wing or main gear supporting the center of the fuselage, the front and back are cantilevered. Think of a hard landing or 2.5G pull up. The most effective structure to support bending is tall, with material on top and bottom (like an I-beam). A flat fuselage would have to be heavier to provide the same strength.

Depending on how you shape it, you're trading wasted space above and below the cabin for having an efficient pressure vessel shape. If you want to fit standard cargo containers below, that constrains your options.

Although you may get some amount of lift from the fuselage it will probably still push the wings and engines outwards by some amount, creating issues with gate width limitations.

In order to meet evacuation requirements, there would need to be more doors or at least emergency exits for a given length. That could mean more cross aisles and less room for seats. It may also be easier to access multiple doors for passenger to board/disembark if they are on different levels than the same level.

Lower ratio of windows to seats. Less natural light. People like window seats.


What is the difference between TAS and GS?

TAS = True Airspeed = speed that you get on radar gun as airplane flies by, when radar gun is held by someone in gondola of balloon in same airmass (wind motion) as airplane.

GS =Groundspeed = speed that you get on radar gun as airplane flies by, when radar gun is held by someone on ground.

As an example: TAS of 200 knots and a headwind of 20 knots gives a GS of 200-20=180 knots.  That is: the plane travels at 180 knots over ground but the air is flowing past the plane at 200 knots.


Can an outside observer tell if an aircraft is flying through turbulence?

The wings are flexing because there is a change in lift.
The wings are more aerodynamic than the body of the aircraft. I.e. the wings are more "responsive", they respond to changed aerodynamic forces more rapidly.
As a result of the change in lift in the wings, the body (being connected to the wings) follow the change.

Therefore, to an observer who is immune to turbulence, the wings would flex first, followed by the aircraft as a whole. If the turbulence is causing the wings to flex up and down repeatedly (e.g. imagine sine wave), the body of the aircraft can be observed lagging behind the wings and smaller in amplitude.


Why do (or did, until very recently) aircraft transponders wait to be interrogated before broadcasting beacon signals?

The Secondary Surveillance Radar system provides range in a method similar to primary radar: by measuring the time between the transmission of the interrogation signal and reception of the reply. The range is proportional to the time difference, minus a constant that allows for the aircraft transponder to perform processing.

This would not work if transponders replied without a interrogation.

Azimuth is traditionally found by observing the direction of the SSR antenna the moment this occurs, though some modern systems utilize the time delay between multiple receiver locations (multilateration).


Would a large airliner such as a 747 or an A380 survive an inversion?

Could it? Yes.
Tex Johnson famously performed a roll in a Boeing 707. If performed properly it is a 1G maneuver (the airframe experiences +1G stresses through the maneuver - as far as it's concerned nothing unusual is happening).

Should you attempt such a maneuver without aerobatic training? No.
Should you attempt it in an aircraft not certificated for aerobatic flight? Absolutely Not.
This is one of those "If you do it wrong the wings fall off" maneuvers, and chances are you're not Tex Johnson.


How are military aircraft directed to targets?

The controller has radar ID of both aircraft. The radar display used is 'smart' in that it can plot the direction and speed of flight of the target and attack aircraft. It then is a simple matter to direct the attacker on a course to intercept the target.  At least that is how I did it, once.


What does pre/post modification mean in Airbus MPD?

It means that operator have to check what status of the particular MOD have the subject A/C, pre or post. Therefore it affects operators MP.


How can a stowaway hide in the undercarriage?

Wheel wells are deceptively large spaces when the gear is down. It is fully possible to climb up and hide inside one. It's a very different story when the gear is retracted. On many aircraft, the gear doors are  closed when the gear is not in motion, making the space look bigger.

They are fairly easy to access through the landing gear with a little bit of climbing, or if low enough (like the example below) just jump up into.

 737 Wheel Well, Petr Volek, from airliners.net

A graphic about a similar event in Hawaii a few months ago:

 From the Independent

Gear stowaways are not new and there have been plenty of occurrences over the years, unfortunately most result in fatalities.

Gear bays are unpressurized, hence normally very cold with air too thin  to sustain life.
Gear bays are very cramped when the gear is up. If you're in the wrong spot, you will be injured.

It is when the landing gear is lowered (and doors opened) for landing that the fatalities occur, assuming they have not already expired from the environment during the flight. Unable to hold onto the airframe and stay off moving parts they (very gruesomely) fall out minutes away from landing. This is also the story that media often picks up.


How should I establish initial contact with ATC after being handed off by another controller?

In your situation:

Oakland Center, Aircraft Identification, Altitude

For example:

Oakland Center, Cessna 123AB, Level four thousand fife hundred.

See Aeronautical Information Manual, 5-3-1: ARTCC Communications.

b. ATC Frequency Change Procedures.
2. The following phraseology should be utilized by pilots for establishing contact with the designated facility:
(a) When operating in a radar environment: On initial contact, the pilot should inform the controller of the aircraft’s assigned altitude preceded by the words “level,” or “climbing to,” or “descending to,” as appropriate; and the aircraft’s present vacating altitude, if applicable.
EXAMPLE-
1. (Name) CENTER, (aircraft identification), LEVEL (altitude or flight level).
2. (Name) CENTER, (aircraft identification), LEAVING (exact altitude or flight level), CLIMBING TO OR DESCENDING TO (altitude of flight level).
NOTE-
Exact altitude or flight level means to the nearest 100 foot increment. Exact altitude or flight level reports on initial contact provide ATC with information required prior to using Mode C altitude information for separation purposes.
(b) When operating in a nonradar environment:
(1) On initial contact, the pilot should inform the controller of the aircraft’s present position, altitude and time estimate for the next reporting point.
EXAMPLE-
(Name) CENTER, (aircraft identification), (position), (altitude), ESTIMATING (reporting point) AT (time).
(2) After initial contact, when a position report will be made, the pilot should give the controller a complete position report.
EXAMPLE-
(Name) CENTER, (aircraft identification), (position), (time), (altitude), (type of flight plan), (ETA and name of next reporting point), (the name of the next succeeding reporting point), AND (remarks).
REFERENCE-
AIM, Position Reporting, Paragraph 5-3-2.


Who designed and built Rans S-7 airplane?

The Ran's S-7 is a kit plane. The article didn't clearly state it, but the gentleman from Ohio bought a Rans kit and assembled it himself, he didn't design the aircraft, he put a kit together.


Can gliders and single-engine planes have vortices?

The vortices that you are referring to (I think) are wing-tip vortices, a product of the wing generating lift.  Since glider wings do generate lift (due to the airflow over the wing) and are propelled (without engine created propulsion) wing-tip vortices are created. Single engine airplanes also create wing-tip vortices since lift is being generated (aided by propulsion)
The jet in your photo is showing "vapor trails" or "contrails" from condensation (from the engines' exhaust) and are not wing-tip vortices.
I'm pretty certain there are a number of engineers on ASE that could provide a more technical answer, but the bottom line is the engines of an airplane do not create vortices (in the context of wing-tip vortices that I believe you are thinking of).


How is an A320 on the ground kept cool inside if the APU fails?

They can leave one engine running to take the place of the APU. If that's not possible for whatever reason, the interior just gets warm.


How to calculate the Glide Ratio from Drag & Lift?

The glide ratio for a given angle of attack is the ratio of lift to drag. Both of these are proportional to the respective coefficients (with a proportionality constant of $\frac12\rho v^2A$), so the glide ratio is simply $c_{\mathrm L}/c_{\mathrm D}$.

Practically, what you're looking for may be the maximal glide ratio. Finding the global maximum of
$$\frac{c_{\mathrm L}}{c_{\mathrm D}} = \frac{c_{\mathrm L}}{0.03+0.095 c_{\mathrm L}^2} = \frac1{c_{\mathrm D}}\sqrt{\frac{c_{\mathrm D}-0.03}{0.095}}=\sqrt{\frac1{0.095}\frac1{c_{\mathrm D}}-\frac{0.03}{0.095}\Bigl(\frac1{c_{\mathrm D}}\Bigr)^2}$$ should be a simple matter of algebra -- for the last expression you don't even need calculus, just finding the apex of a parabola.


What's the acceleration and absolute minimal RWY length for an A320 during take-off?

At takeoff weight of 78.9 tonnes and -20°C temperature (best case scenario), the A320 needs 2,250 metres (7,400 feet). (This includes the distance to reject a takeoff.)

As for the forces, you forgot to take into account the aerodynamic drag and rolling friction, both will slow down the acceleration.

This PDF from Virginia Tech explains the forces at work and the equations needed.


Why was a complete test flight of Hughes Hercules H-4 (Spruce Goose) never undertaken?

By the time the government had pulled the plug on the program. Even that hop got Hughes into trouble because they had been expressly forbidden from taking off (he got off on a technicality, claiming it'd been unintentional, unexpected behaviour from an experimental machine, etc.).

If it had been anyone except Hughes I'm pretty sure the H4 would have been destroyed rather than preserved as a museum piece, the US government was that intent on killing the project there and then. They had a lot of air bases with long runways to find a purpose for, and long range air travel was an excellent purpose. They also wanted to find customers for the thousands of surplus transport aircraft (and bombers to be converted to that role). So getting rid of the traditional way to fly intercontinental, the flying boat, was important.

Were people curious? No doubt. But they also were budget conscious, the H4 had no more military application so there was no money coming out of the Pentagon. It had no civilian application, as for large payload ships are cheaper and for small, fast payloads it was too large. So even if there had not been active hostility towards the flying boat concept at the time from people with the power to release or deny budgets, there would have been little point in implementing an expensive flight test program (which usually requires multiple vehicles...) for an aircraft for which it was highly unlikely there would ever be any peacetime orders.

Of course 50 years later the idea was kinda revived with a short period of interest in Wing In Ground effect vehicles to fly troops and supplies over the feared Soviet submarine fleet in the Atlantic. But that didn't start up until near the demise of that threat in the 1990s and nothing ever made it past concept drawings (except paradoxically a few Soviet craft in the Caspian and Black Sea regions, the Ekranoplans).

I've little doubt the H4 would have worked as advertised, seeing it it looks sound in design, basically a scaled up B314. But there was just no market for it. It was an example of too big, too late.


What can a new student pilot do on their own to prepare for class and instruction?

Usually the best way is to call your local flight school and ask to take a discovery flight.  It’s a 30 minute or so flight in a Cessna 172 or similar aircraft and you’ll get a good introduction to flying, even some stick time in the airplane.

If you’re looking for material to read on the subject of learning to fly, I suggest getting copies of the pilots handbook of aeronautical knowledge, and the airplane flying handbook. Both are available for free as PDFs on the FAA’s website.  They will be the fundamental textbooks for your private pilot training and most of the knowledge and practical information on flying that the FAA will test you on are going to come from these documents.


What are these unsymmetrical parts at the tail of the Tupolev TU-144?

The four parts you're referring to contain the actuation mechanism for the rudder, similar to the wing pods that contain the flap actuation mechanism.

The reason they are not arranged symmetrically is that the rudder has two sections (you can see the 'cut' in the middle in your image)- apparently to provide redundancy and improve safety. So,each section has two actuation mechanisms on the same side, with both of them in opposite sides.

The Concorde had a similar arrangement, albeit with only a single mechanism on either side, as can be seen below.

By Simon Boddy, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=31619795


Can a transonic airfoil have two shock waves?

Very Interesting results. I must say I have never before seen such a peculiar case. Yes, theoretically it seems possible to have this situation, but it's difficult to say if this is possible in reality or not. I found another similar behavior mentioned here:

One of the three aerofoils has dual shock.
It's difficult to say whether it's a physically correct situation or a mere artifact of CFD, especially without data on type of solver, type of simulation, numerical methods employed, mesh details etc. It would be advisable to simulate the same case in another code and see what results are seen.


Can the dome gunner on a B-17 Flying Fortress shoot the plane's tail off?

There's a profile cam in the turret track ring that operates a mechanism that interrupts the guns when the barrels are pointed at parts of the aircraft.  Waist gunners were the only ones who had to worry about hitting their own plane.

The bigger problem was gunners hitting adjacent aircraft.  The "box" formation design attempted to provide as much of an open field as possible to each gunner.


Why does the 737 auto-land trim up at around 400 feet RA?

My educated guess is that they had to find a way to give the autopilot more pitch authority for Autoland.  It's possible that the pitch feel system force the AP servo has to work against to flare the airplane, which would be more than its normal in-flight range and would also need to include some margin to apply more than the normal flaring range if necessary, is more than the servo can handle for one reason or another.  Slip clutch limits, torque load limits, maybe the operating range of the servo capstan, something like that.  Possibly it was fine for 95% of conditions but there were extreme cases uncovered in testing that had to be catered to.

So the system sets stab trim to a slower speed, which requires the AP servo to maintain a nose down load to maintain Vref.  The servo now has increased effective pitch up range because the first part of the flare action is just to stop pushing, and from there is has the normal nose-up-from-neutral range available as additional authority.

Rather than go to all the trouble to certify a new, more powerful servo, they worked out this little cheat to get the extra pitch range they needed.

Just a theory, which assumes this feature is only active during Autoland.  An alternative theory (say if the same feature works in normal non-Autoland approaches) would be they wanted a positive pitch up tendency built in if the GA button is pushed due to the airplane's behaviour somehow.


Where can I find a cross sectional area plot for the A320 or other modern airliners?

There seem to be plenty of drawings available with A320 dimesions.

https://www.google.com/search?q=a320+cross+sectional+area&tbm=isch&source=iu&ictx=1&fir=xqsB2UJmwNJExM%253A%252CZ-goV0XUZnxtFM%252C_&usg=__VvKRKRr0Rto02mNZc1OcLUazPPY%3D&sa=X&ved=0ahUKEwjUpvCm54XbAhWBPZoKHXyTC9gQ9QEILTAB#imgdii=3XaIv6qHo-5doM:&imgrc=IdDuWmIhnnky0M:  I'd suggest pulling the data from several as needed and model the A320 so you can try changes in SolidWorks as the Raptor design team did for their video.

Maybe SolidWorks has a student license you can download & use.

https://www.solidworks.com/


How much pressure does the compressor of an engine of B787 exert on air?

Wikipedia will tell you that two engines are offered for the 787, namely the General Electric GEnx and the Rolls-Royce Trent 1000. Their overall compression ratios are given as 52:1 for the Trent 1000 and 41:1 for the GEnx.

Note, however, that this just one point which will change over the whole operating envelope. In case of the Trent 1000, the point is given as "top of climb", whereas the number for the GEnx is given without context. At high speed, the intake will already raise the pressure at the compressor entry by approximately 20%.

If we now assume that ambient pressure at the (not specified) top-of-climb altitude is a quarter of sea level pressure and add the intake pressure increase, the total pressure of the air inside the engine at the compressor exit of the Trent 1000 is 1,580,000 Pascal or 15.6 times sea level pressure.

In the static case (at rest, on the ground), the engine needs to actively suck in air, so the pressure at the compressor entry is lower than ambient (approximately 88% of ambient pressure). If we now assume that the compression ratio is around 45, the absolute pressure at the compressor exit would be 4,012,500 Pascal or 40 times sea level pressure.


After passing a checkride, can I get the plastic certificate card by visiting the nearest FSDO?

No, sorry. They don’t have the device at the FSDO that would produce a plastic card.

If you want to see the page that shows what date they are currently processing for, click here.

Unfortunately it’s typically around 6-8 weeks.


What is the function of interplane strut of a Biplane?

The wing strut prevents the lower wing from bending upwards due to the lift forces.

The biplane is a truss structure: rectangular shapes are "crossed out" by diagonal structural members, in order to create triangular shapes with only tension and compression in their structural members, no bending. If the diagonal is a rod, it can transfer both compression and tension forces and only one diagonal is required. If it is a cable, it can only transfer tension forces, and the other diagonal needs to be crossed out by a cable as well.

In flight, lift wants to bend the wings upward and lengthen the diagonal, which becomes tension loaded. The upper wing is then prevented from bending upwards and becomes compression loaded.

The interplane strut connects the lower wing with the upper wing, and prevents the lower wing from bending upwards. It is compression loaded: the diagonal exerts a downward force, lower wing lift exerts an upward force.

The method of how to compute the force is in this answer. In a truss structure the intersection points are modelled as hinges, and the structure members are dimensioned to carry the resulting tension/compression loads.


How does flying at ECON computed speeds optimise fuel burn.?

The key is the word 'Econ', which has nothing to do with 'Fuel Burn'. The 'Econ' setting is a MIN COST method of operating, taking into account not just the cost of the fuel, but also the other operating costs of the airplane.
If your hourly costs (maintenance, crew) are high, then you'd burn fuel to get there fast with reduced hours. If your hourly costs are low, then it's worth flying slow, and thus conserving fuel.


How to select and electric propulsion system for my experimental Ultralight?

FLÜGEL World Directory Of Light Aviation 2019/2020 - English PDF could be a good starting point. On pages 278 - 281, a total of 71 lines of electric motors from 42 manufacturers are featured. Disclaimer 1: some data fields are incomplete for many of the entries. There are German, English French and Chinese versions in paper and pdf, starting at €8. Here's the paper version in German:
Welt-Index Ultraleicht und Flugzeug 2019/20 Wings of the World

In any version, the aircraft listings themselves may also be of interest, as aircraft models which are available with electric motors as the primary powerplant are highlighted with a green e icon. In browsing those, you may glean some emperical inspiration in terms of electric motor vs aircraft size. Disclaimer 2: the power-plant details for the aircraft listings are not always complete.

The free annual e-flight Journal by the same publisher includes motor manufacturer adverts which may be of some use.

Lastly, at the end of the online Kitplanes 2020 Engine Buyer’s Guide are four electric motors from one manufacturer.

Final Disclaimer: I have no vested interest in these magazines, publisher or any products listed or advertised.


Is it possible and effective to perform a forward slip in a large commercial jet?

It's it possible?  Yes, you would do it the same way as in any other airplane.

Is it effective?  Yes, just look at all of the fuselage area that is exposed to the relative wind.

Is it useful?  Not really.  With all of the other drag devices, you shouldn't really need it.

Is it recommended?  You would have to check the AFM.  I looked in the A320 Flight Crew Training Manual and there is no limitation against it, but if you need to slip then that's a strong indication of poor planning and an unstabilized approach which would require a go around.  Even at higher altitudes, it isn't very comfortable for the passengers!


What is a typical altitude for a dogfight?

At what altitude(s) do dogfights typically occur?

All of them.

Throughout history dogfights have generally started at one of the aircraft's "best altitude", which depends on the aircraft, and then descended as the pilot's trade altitude for airspeed.

Altitude disparity can be so great that one or the other will simply not engage, or do so at a serious penalty if they are forced to. This occurred during the Falklands when the Argentinian aircraft had much more performance than the UK's Harriers, but only at higher altitudes. The Harriers simply refused to fight them, so if the Argentines wanted to get to the ships they had to fly down where the Harriers had the advantage. The same occurred during WWII when US B-17's flew at altitudes where German fighters were struggling, allowing the escorting P-51's to chew them up.

It is not uncommon for extended dogfights to end with troops on the ground shooting down some of the aircraft, as was the case with the Red Baron (or so the Australians will claim).


Why are the Boeing 737 nacelles odd shaped?

The engine in question is a CFM56 turbofan engine which is larger than the JT8D the plane was originally designed for and thus has less ground clearance. This meant that they needed to flatten the bottom by moving the accessory gearbox to the side from the bottom and shrinking the fan.

To quote Wikipedia:

  In the early 1980s Boeing selected the CFM56-3 to exclusively power
  the latest Boeing 737 variant, the 737-300. The 737 wings were closer
  to the ground than previous applications for the CFM56, necessitating
  several modifications to the engine. The fan diameter was reduced,
  which reduced the bypass ratio, and the engine accessory gearbox was
  moved from the bottom of the engine (the 6 o'clock position) to the 9
  o'clock position, giving the engine nacelle its distinctive
  flat-bottomed shape. The overall thrust was also reduced, from 24,000
  to 20,000 lbf (107 to 89 kN), mostly due to the reduction in bypass
  ratio.

They also mounted the engine in front of the wing rather than below to get every bit of clearance they could.


What are the black boots on this Extra 300's prop?

The inner portion of the blade is protected by a self-adhesive PU-strip, unless the blade is equipped with a de-ice boot.

The outboard edge as you can see in the very lower-right corner is protected with a stainless steel erosion sheath. Since the inboard section is slower (radial speed), its protection is a lighter polyurethane-strip/tape.

The Extra 300's service manual lists the 3-blade prop as one of two MTV-9 series (you can see the MT logo already in your photo). The above quote and illustration are from the MTV-9 series operation manual from mt-propeller.com. An example tape is the 3M 8663HS, which comes in black or transparent.


I have trouble understanding why the ball (on the turn & slip indicator) falls into the turn ... in an uncoordinated turn (slipping
  turn). What are the forces that goes into this?

The ball is displaced to one side because the aircraft is being allowed to fly sideways through the air.  The nose is not aligned with the instantaneous direction of the flight path, but rather is yawed to point to the left or right of the instantaneous direction of the flight path.

As a result, the airflow is striking the side of the aircraft and generating an aerodynamic sideforce, which is what causes the ball to displace to the side.

There are many reasons why an aircraft might tend to fly yawed slightly toward the left or the right in a turn.  Most of these reasons tend to promote a slip, rather than a skid.  Other than the most obvious reason of a significant, intentional deflection of the rudder by the pilot, these reasons include the curving nature of the relative wind during turning flight and its effects on tail surfaces (also described as "aerodynamic damping"), and the fact that the outboard wingtip must move faster, and thus tends to generate more drag, than the inboard wingtip.  In an aircraft with a propeller, P-factor can also play a role, tending to promote either a slip or a skid depending on the direction of turn.  The setting of the rudder trim may also be factor.  When the bank angle is changing, adverse yaw from the deflected ailerons and from the rolling motion itself plays a major role, strongly tending to promote a slip when the bank angle is increasing and a skid when the bank angle is decreasing.  In all cases, the cure is for the pilot to use the rudder as needed to compensate for these effects and align the nose of the aircraft with the instantanous direction of the flight path, so the nose is pointing straight into the "relative wind" and the airflow is not hitting the side of the fuselage.

Note that "having too little or too much lift in relation to the bank angle" or "having too little or too much centrifugal force in relation to the bank angle" are not causes of slips or skids.  Rather, they are results of slips or skids.  The causes are the aerodynamic effects listed above, creating a yaw torque that makes the aircraft fly slightly sideways through the air, despite the generally stabilizing effect of the vertical fin.  More on this later.

So why does the slip-skid ball get displaced off center when the aircraft flies sideways through the air?  When the airflow hits the side of the fuselage, this generates an aerodynamic sideforce, acting orthogonal (perpendicular) to the flight path in the direction that is roughly parallel to the wingspan,  This sideforce points toward the high wingtip in a slip, and toward the low wingtip in a skid.  This real aerodynamic force has been completely omitted from the diagram of the slipping turn attached to your question.  This is a major flaw in the diagram.

This aerodynamic sideforce contributes to the net aerodynamic force generated by the aircraft, so that the net aerodynamic force vector is no longer pointing
straight up" in the aircraft's reference frame, i.e. parallel to the vertical fin.

The slip-skid ball always tends to position itself in the curved glass tube at the point in the tube that is exactly perpendicular to the net aerodynamic force vector.  If the ball is positioned at any other point in the tube, it will "feel" an apparent force to the left or right, and will shift position.  If the net aerodynamic force is not pointing "straight up" in the aircraft's reference frame, then the ball will not position itself at the "bottom", i.e. at the center, of the curved glass tube.

Another way to look at the situation is to consider the apparent "load" acting on the ball, due to the combined effect of weight and "centrifugal force".  The ball always tends to position itself in the curved glass tube at the point in the tube that is exactly perpendicular to the "load" vector.  If the "load" vector is not pointing "straight down" in the aircraft's reference frame, then the ball will not position itself at the "bottom", i.e. at the center, of the curved glass tube.

The key thing to understand is that the apparent "load" felt by the aircraft structure and contents, including the pilot and the slip-skid ball, is nothing more than the mirror image of the real aerodynamic force vector generated by the aircraft.  This is explored in more detail in a several answers to the related ASE question "Forces "felt" by pilot, G-meter, inclinometer--are they the aerodynamic forces generated by the aircraft, or the sum of weight+centrifugal force?".

The diagram is misleading because it suggests that some mysterious effect, presumably somehow related to turn rate, yet seemingly unrelated to any real aerodynamic force, is affecting the amount of "centrifugal force" generated by the aircraft or acting on the aircraft.  This is false.  The difference in the magnitude of the "centrifugal force" vector between a "coordinated" turn and a "slipping" turn is due to the way that a sideslip generates a real aerodynamic sideforce vector, as described above.

While it is in fact true that the "load" acting on the ball can be said to be equal to the vector sum of weight and "centrifugal force", this is not a concept that has a lot of explanatory power, unless we understand that the "centrifugal force" is intimately related to the real aerodynamic forces generated by the aircraft.  The "load" vector, which can be said to be the vector sum of weight and "centrifugal force", is nothing more than the mirror image of the real aerodynamic force generated by the aircraft.  The "load" vector is always equal and opposite to the vector representing the real aerodynamic force generated by the aircraft.1

An extreme case of a slipping turn is a forward slip or sideslip (these are actually exactly the same thing, just aimed differently in relation to the target), where the aerodynamic sideforce from the slip is sufficient to bring the turn rate all the way to zero, creating a linear flight path.  Whenever the flight path is linear, the slip-skid ball doubles as bank angle gauge.  The most extreme case of a non-turning (linear) sideslip is vertically-banked sustained knife-edge flight, like we often see at an airshow.  In this case the aerodynamic sideforce vector from the airflow striking the side of the fuselage (plus an additional component due to the engine thrust line being aimed above the horizon) is supporting the entire weight of the aircraft, and the wing's lift vector is zero.  In this case, the "load" vector is simply equal and opposite the aerodynamic sideforce vector from the slip (including the component due the engine thrust), because aerodynamic sideforce vector and the net aerodynamic force vector are one and the same.  The net aerodynamic force vector is equal to the weight of the aircraft but acting in the upward direction, while the "load" vector is equal to weight of the aircraft, acting in the downward direction.

While established in a steady-state turn at a constant turn rate and airspeed, trimmed for hands-off flight, if we then pull aft on the stick to "load up" the wing with "extra" lift to boost the G-load to a higher-than-normal value for the bank angle, or if we push the stick forward to "unload" the wing to decrease the lift vector and drop the G-load to a lower-than-normal value for the bank angle, the turn rate will immediately change, and so will the horizontal component of the "centrifugal force" vector.  The diagram above might tend to lead us to think that the ball will immediately shift off-center.  This is not the case.

In a situation like this, the flight path will curve up or down, introducing a vertical component of "centrifugal force".  The vector sum of weight and centrifugal force will still be "straight down" in the aircraft's reference frame, and the ball will stay centered.

Or to look at it from a much simpler perspective-- when we pull the stick aft or push the stick forward to change the wing's angle-of-attack, we are increasing or decreasing the magnitude of the lift vector, but we aren't introducing any aerodynamic sideforces-- we aren't yawing the fuselage to fly sideways through the air.  Because the net aerodynamic force vector still acts "straight up" in the aircraft's own reference frame-- parallel to the direction that the vertical fin is pointing-- the ball still stays centered.

(For simplicity, we're ignoring the forward or aft components in the net aerodynamic force vector-- the components that wouldn't show up in a head-on view of the aircraft.  The basic explanation here remains the same regardless of whether thrust is exactly in balance with drag, or not.)

Of course, "loading" or "unloading" the wing in this manner during a turn will also drive a change in airspeed, as the flight path curves up or down.  For an aircraft of a given weight at a given bank angle, there is only one value of the lift vector (G-loading) that will yield a steady-state turn at constant airspeed.2

  From reading up online, many sources quote that in a slipping turn, the aircraft is banked too much for the rate of turn.

From the content above, you'll see that this isn't always true.  It can be true given certain constraints, but it is not a concept with a lot of explanatory power.

As noted above, if we are established in a stabilized turn, and then we pull the stick back, or push the stick forward, to boost or decrease the lift vector and G-loading, the turn rate immediately changes, but the ball does not shift off-center.3

The idea that (for a turn at a given airspeed) "in a slipping turn, the aircraft is banked too much for the rate of turn" is only true given the constraint that there is zero upward or downward (skyward or earthward) curvature in the flight path.  And the only way4 that (for a given airspeed) we can have a mismatch between the bank angle and turn rate, while not allowing the flight path to curve up and down, is that we are applying the rudder to expose the side of the fuselage to the airflow and generate an aerodynamic sideforce, or we are failing to apply the rudder as needed to cancel out other aerodynamic torques that are tending to expose the side of the fuselage to the airflow.  If we do this, while adding or subtracting power as needed, we can indeed create the following situations.  Starting from a stabilized coordinated turn at a constant airspeed and altitude, we can--

a) vary the turn rate and turn radius while holding altitude, airspeed, and bank angle constant

b) vary the bank angle and while holding altitude, airspeed, and turn rate and radius constant

The ball will deflect off center in both of these sitations.  It is equally true to say that the ball goes off-center because the centrifugal force vector is no longer correctly matched to the bank angle, or because the load vector (the vector sum of centrifugal force and weight) no longer points straight "down" in the aircraft's reference frame (i.e. parallel to the vertical fin), or because the net aerodynamic force vector no longer points straight "up" in the aircraft's reference frame (parallel to the vertical fin), or because the pilot is using the rudder in a way that exposes the side of the fuselage to the airflow, which generates an aerodynamic sideforce.

The pilot's rudder usage is the key to centering the slip-skid ball, or to intentionally driving it off center.  The sideways force we "feel" in a slip is the real aerodynamic force generated by the air striking the side of the fuselage, which changes the direction of the net aerodynamic force vector, and its mirror image, the "load" vector.  Explanations centered around some sort of "balance" or "imbalance" between bank angle and turn rate, or bank angle and lift force, or bank angle and G-loading, are misleading, and have little explanatory power, and certainly do not apply to aerobatic flight.  These explanations tend to obscure, rather than illuminate, what is really going on.

Some of these sorts of explanations are well suited to a car driving on banked track, or a bobsled going down a banked track, but not to flight, where the trajectory is not constrained to have a specific turn radius, and also is not constrained to have no upward or downward (skyward or earthward) curvature.5

Note that in flight, generally speaking, changing airspeed while holding the bank angle constant creates no tendency toward a slip or skid, though the turn rate and radius will both vary.  As long as the net aerodynamic force vector continues to point "straight up" in the aircraft's reference frame, there will be no slip or skid.  Though again, we can come up with specific contrived situations where varying the airspeed while holding the bank angle constant does cause a slip or skid-- for example if the turn rate and radius are constrained to remain constant as the airspeed is changed.  Again, this can only happen if the pilot applies the rudder to expose the side of the fuselage to the airflow, generating an aerodynamic sideforce.

  I have trouble understanding why

This is not surprising, because you have been provided with faulty explanations, as well as faulty diagrams.  The diagrams attached to your question have omitted the aerodynamic sideforce vector caused by the airflow striking the side of the fuselage.  The diagrams attached to your question give the impression that the net aerodynamic force vector generated by the aircraft is the same in all 3 cases (coordinated flight, slipping flight, and skidding flight), when it actually is not.  The diagrams attached to your question give the impression that the "load" vector can somehow be something other than the mirror image of the net aerodynamic force vector, when it actually cannot be anything other than the mirror image of the net aerodynamic force vector.

To read more about the specific errors in the vector diagrams attached to your question, see the related question What is missing from these diagrams of the forces in slips and skids? and answer What is missing from these diagrams of the forces in slips and skids? .

Other related ASE questions or answers:

(Q) Forces "felt" by pilot, G-meter, inclinometer--are they the aerodynamic forces generated by the aircraft, or the sum of weight+centrifugal force?

(A) Forces "felt" by pilot, G-meter, inclinometer--are they the aerodynamic forces generated by the aircraft, or the sum of weight+centrifugal force?

(Q) What does the balance ball actually indicate?

(A) What does the balance ball actually indicate?

The topic of accuracy of the diagrams illustrated in your question has also been discussed on Physics Stack Exchange.  See--

(Q) Is this vector diagram of the forces at play in turning flight correct?

(A) Is this vector diagram of the forces at play in turning flight correct?

Footnotes

1 -- For simplicity, we're assuming that the slip-skid ball is located near the aircraft's CG, or aircraft's yaw rotational rate is constant, or both.  A change in the yaw rotational rate will create an apparent centrifugal or inertial force that displaces the slip-skid ball to one side if it is located far forward or aft of the CG, and this displacement does not reflect any real aerodynamic force component.  For example, if the yaw rotational rate is increasing toward the left, a slip-skid ball located far in front of the CG would tend to be displaced toward the right, and a slip-skid ball located far aft of the CG would tend to be displaced toward the left.  These second-order effects are beyond the intended scope of this answer, and are also beyond the scope of what pilots are generally able to notice in actual flight.

2 -- For simplicity, we're overlooking the fact that magnitude of the lift vector associated with a steady-state coordinated turn at some particular bank angle and some particular airspeed and angle-of-attack is very slightly different when we are descending or climbing, than when we are maintaining altitude (with respect to the airmass in all cases).  For modest dives and climbs, this is a very minor effect and definitely not something that someone still learning about the basics of slips and skids should concern themselves with, but in the interest of accuracy, this point should not be completely omitted.  To learn more about the "unloading" of the lift vector in a descent or climb, see What produces thrust along the line of flight in a glider? and Does lift equal weight in a climb?

3 -- Surprisingly, Wolfgang Langewiesche's classic flight-mechanics-for-pilots book "Stick and Rudder" (1944), which contains a lot of good material on the physics of turning flight, does make the claim (see pages 205, 219-220, and 223-226) that while excess back pressure on the stick does not cause a slip or skid, too little back pressure on the stick can cause a slip, with the ball deflected to the low side of the turn, which should be corrected by increasing back pressure rather than by applying inside rudder.  This is probably the only faulty idea in the entire book.  The 3rd edition of the book "Modern Airmanship" (1966, edited by Neil Van Sickle, Major General USAF) has similar content on pages 308-309.  By the 8th (1999) edition of "Van Sickle’s Modern Airmanship", edited by John F. Welch, Lewis Bjork, and Linda Bjork, this content had been deleted, while the remaining content on the physics of turning flight had been retained (page 441).  For more, including specific quotes from these books, see https://web.archive.org/web/20180905112047/http://aeroexperiments.org/critiques.shtml .

4 -- Strictly speaking, it's not exactly true that the only way that (for a given airspeed) we can have a mismatch between the bank angle and turn rate, while not allowing the flight path to curve up and down, is to deflect the rudder to the side in a way that exposes the side of the fuselage to the airflow.  But it's a good first approximation.  For a more nuanced view, we have to consider the effect of the sideforce generated by the rudder itself.  For example, we could shut down one engine on a conventional piston twin and apply the rudder just enough to keep the fuselage exactly aligned with the airflow.  Since the sideforce from the rudder itself is not zero, the ball will be slightly deflected (toward the working engine) when the nose of the aircraft is pointing straight into the relative wind.  If we bank into the good engine as needed to cancel all turning tendency, we'll end up flying along in a straight line (zero turn rate) while banked slightly toward the good engine, as discussed in detail elsewhere on ASE, such as here, here, and here (link to be added).

5 -- Speaking of bobslebs on curved tracks, "Hang Gliding Training Manual" and "Performance Flying" by Dennis Pagen both include extensive content-- including an illustration of a bobsled on a track-- purporting to show how, as a pilot enters a turn while flying a hang glider, if he or she doesn't immediately "load up" the wing with an adequate pitch input, the glider will slip sideways through the air, toward the low wingtip.  Also the idea that an intentional reduction of angle-of-attack and lift and G-loading while turning will make the glider slip sideways through the air toward the low wingtip.  See for example pp. 128-129 in "Hang Gliding Training Manual", and page 45 in "Performance Flying".  A similar idea appears on page 70 of Peter Cheney's "Hang Gliding for Beginner Pilots" (3rd edition, 1997).  I've checked these ideas in flight with a yaw string, in hang gliders as well as conventional aircraft, and found no basis for them.  For more on the content in these books, see https://web.archive.org/web/20180905112047/http://aeroexperiments.org/critiques.shtml .


What does this METAR remark mean? 'RMK RWY 7 ATIS G LL'

I have a suspicion that you're looking at KLZU's METAR. Basically, they're inputting their manually written METAR into the system, and when they send it out they're adding the Runway in Use(RWY 7) and ATIS code(ATIS G) to their METAR, which they're really not supposed to do. I suspect that LL is the person who recorded it's operating initials at the facility, also not supposed to be transmitted as a part of the METAR.


Yes, they can, these are called lifting body aircraft.

Source: Wikimedia

They maintain directional stability using the control surfaces near the tail.

If you like retro documentaries, here's one on YouTube about lifting bodies done by NASA.

As for aircraft that normally have wings, they can sometimes fly when losing (most) of one of them:


Why does thrust-to-weight ratio depend from max Mach number?

Disclaimer: I have no copy of Raymer's book, so I have to guess what this table looks like.

There should be no direct dependency, except that all aircraft need to operate in the real world. If you look at the wing loading of regular jet transports, you will notice that they bunch together around 500 - 600 kg/m². This is the maximum wing loading which still allows them to operate from normal airports - go to higher values an you need a dry lakebed for take-offs and especially landings.

To push the resulting wing to higher flight speeds needs more thrust - hence the dependency. If you start with a higher wing loading (say, 800 kg/m²), the thrust/weight ratio for reaching the same Mach number is lower. The approach and landing speeds grow with wing loading as well, which in turn affects the resulting landing distance. I guess there is a maximum landing distance requirement for all aircraft in the table which is not explicitly mentioned.


How works the system of frequency for aircraft commercial Airline

I think you have a misunderstanding on how individual radio frequencies are used.

Individual radio frequencies are not assigned to aircraft.  They are assigned to Air Traffic Control facilities like Control Towers or Area Control centers.

Each aircraft will have it's own "radio licence" but they can tune in any frequency that is needed for both transmitting and receiving. All aircraft in a specific area will use the same frequency as assigned by ATC. You may have 20 or 30 aircraft on the same frequency, but only one aircraft should be transmitting at any time.

There is a lot of congestion on the radios in a busy sector and "CPDLC" (Controller–pilot data link communications) is gradually being introduced in many areas. This allows ATC and the pilot to communicate directly via data-link text messages.

In some areas where there is no ATC control, aircraft can monitor or communicate on a common "air to air" frequency.  123.45 is used in some areas.


Why the "Terminal" in Terminal Aerodrome Forecast?

Terminal refers to the airspace near the airport, more or less similar to the ATC usage of terminal as in "terminal airspace" or area. TAFs cover the airspace in a 5 mi radius of an aerodrome, the immediate terminal area. The T in METAR also refers to terminal as in "Meteorological Terminal Aviation Routine Weather Report".


Running torque is also called the "friction torque". It's the torque required to make the nut or bolt turn while the nut is "loose" you might say.  With a locking nut, the locking feature (normally either a plastic insert, or a distorted bore section of the threads that directly squeezes together on them) takes a certain amount of effort to overcome.

Since torque value is an attempt to measure the stretch in a bolt as the rotary sliding wedge of the threads is applied to pull the two ends apart, any rotational resistance forces that are added, not directly applying the clamping force to the part, will skew the final result.

If you torque to 100 inlbs, and it takes 30 inlbs of torque just to make the nut turn because it's a lock nut, when the wrench trips at 100 inlb you will only have actually applied 70 inlbs worth of "stretch" to the bolt. So if you measure 30 inlb while spinning the nut down before it clamps down, you add that to the 100 inlb value, and run the wrench to 130 and will have the proper 100 inlb application to the bolt or stud.

The proper procedure is to run the nut or bolt down to maybe half a turn to contact (washer still loose).  Measure the torque required just to move the nut the last bit before the nut makes contact, and add that to the total.  If the nut spins freely because it's a castellated nut and has no friction device and you can spin it down all the way with your fingers, don't bother because the value will be too low to measure.

This is the problem with preset click-over torque wrenches that can only measure a limit that is set beforehand, when torquing friction-locking nuts.  When a procedure calls for that running torque part, it's better to use a dial indicating or other continuous indication torque wrench that lets you do the running torque observation and addition to the final value on the fly.

When a torque is for a critical part where precision is essential, it's also important to get to the final torque in one motion value without stopping.  That's because if you stop mid way just below the final value, the torque required to get started again will be high, and may be higher than the final value, and you may get a false "I'm there" indication when you really weren't there yet.  Better to back off half a turn and do it again.

If a torque spec says to lubricate threads, this is critical as well, as the friction of the thread and nut interface itself, while the clamping force is being applied, can skew the final result. On aircraft cylinders, where a precise torque application is vital, it's standard procedure to use lots of the recommended oil on the nut and threads to get the thread friction, and the nut to flange friction, as low as possible.  Piston engine cylinder nuts generally don't use any locking devices (or washers) at all, and totally depend on clamping force to avoid backing off, and if done properly, they never do.

In the procedure you're quoting, the objective is to seat the "plug" for some reason with a larger than final force, then back off and re-tighten to a pretty low value of 15-20 (this sounds like a procedure intended for sealing purposes). Factoring in the running torque will be critical to achieving the 15-20 inlb final value.


Why do the 737-100/200’s thrust reversers blow fully open if hydraulic pressure is removed while the reversers are partly open?

If the buckets could be opened by engine thrust, they would be ineffective to reduce speed. By the same token, you want airflow to help them deploy when needed. The controlling force then is the hydraulic actuators. Without hydraulic power it would be very difficult to achieve positive control over the buckets' position.


Are ADS-B Airborne Squitters inherently inaccurate?

Yes, there is a inherently inaccuracy caused by the delay between a position is determined by the GPS receiver and the time it is transmitted.

However, for installation certified for the EU and USA ADS-B regulations, the inaccuracy is very limited. The accuracy of ADS-B is therefor better than radar even when ignoring the latency in radar systems.

The first part of the latency is caused in the GPS unit itself; there is some processing time between the position signals arrive at the GPS antenna and the  of the time of output of the computed position. Further delay can occur if the GPS-receiver is not directly wired to the transponder. If the position signal has to travel through another box (for example the ADIRU) additional latency can occur.

Finally the position arrives in the transponder and is delayed until the next position message is scheduled for transmission.

In installations certified for the ADS-B mandates of the EU and the USA, the position latency is limited to 0.6 seconds. This is usually achieved by direct wiring the GPS to the transponder. Additionally the latency is compensated for by extrapolating the position using the ground speed vector. The position within the transponder is thus update periodically (e.g. at 10 Hz) using the groundspeed vector. This extrapolation reduces the effect of latency by introducing a small error based on the accuracy of the groundspeed vector and any manoeuvring going on.

The total accuracy of the ADS-B signal is the combination of

GPS accuracy
accuracy of speed vector used in the latency compensation
manoeuvring going on between the time of position validity and time of transmission not compensated for by the linear extrapolation using the speed vector
residual uncompensated latency

In some installations the residual uncompensated latency is negative (i.e. the position is over-extrapolated). The limit is 0.2 seconds ahead of the current position. The recommendation in the ADS-B Minimum Operational Performance Standard (MOPS) is that the uncompensated latency should not be more than 0.4 seconds.

Note that most of the inaccuracy due to latency is only observable in the along-track direction.

The magnitude of the position error caused by the latency is very limited.
For an aircraft flying 270 meter per second (972 km/h, 525 KTAS), the upper bound of 0.6 seconds latency limits the error to 162 meter. That is much better than the position accuracy that en-route radars typically achieve (and in addition, radar also has latency).

In the TMA, the speeds are usually slower and so are the latency induced errors. So ADS-B here outperforms the TMA radars.

For reference, the 0.6 seconds is a limitation in the USA is from FAA AC20-165A (PDF) and in the EU from EU 1207/2011 (applicability dates amended by EU 1028/2014). The full Certification Specifications for ADS-B in the European Union can be found in the CS-ACNS.


Which Terminal Arrival Area depiction is correct between NACO and Jeppesen plates?

I'm not familiar with Jepp plates but as far as I can see both plates are the same, it's just that Jepp chose not to depict ACUBO on the base area icons (as the FAA calls them). I assume that's to reduce clutter on the chart but I don't know for sure. In any event, I don't see how it would change the procedure in any way: all the fixes are still shown on both plates, and all the details seem to be the same.

As for the HILPT, the rule for procedure turns is that by default you have to fly them unless you have a valid reason not to (see this question). In the case of this approach, the plate says NoPT if you're approaching from the straight-in area or on the direct tracks from CADAC/BEBAC to ACUBO. If you get to ACUBO any other way, you have to fly the HILPT. The most likely reason would be that you're coming from the south and ATC vectors you directly to ACUBO rather than to CADAC or BEBAC: "N12345, proceed direct ACUBO, cleared for the RNAV 19R approach".

The FAA Instrument Procedure Handbook (chapter 4, p. 4-58) has detailed information on TAAs, including this:

  ATC may clear aircraft direct to the fix labeled IF/IAF if the course
  to the IF/IAF is within the straight-in sector labeled “NoPT” and the
  intercept angle does not exceed 90 degrees. Pilots are expected to
  proceed direct to the IF/ IAF and accomplish a straight-in approach.
  Do not execute HILO course reversal. Pilots are also expected to fly
  the straight−in approach when ATC provides radar vectors and
  monitoring to the IF/IAF and issues a “straight-in” approach clearance;
  otherwise, the pilot is expected to execute the HILO course reversal.

But even if ATC vectors you to ACUBO they can't give you a straight-in clearance if your intercept angle is greater than 90 degrees (ATC Orders 4-8-1(d)
 and (e)).

You also asked in a comment what happens if ATC clears you for the approach without specifying the IAF. That's explained in the IPH:

  On rare occasions, ATC may clear the aircraft for an approach at the
  airport without specifying the approach procedure by name or by a
  specific approach (e.g., “cleared RNAV Runway 34 approach”) without
  specifying a particular IAF. In either case, the pilot should proceed
  direct to the IAF or to the IF/IAF associated with the sector that the
  aircraft will enter the TAA and join the approach course from that
  point and if required by that sector (i.e., sector is not labeled
  “NoPT), complete the HILO course reversal.


Do all airplanes have the same turning radius when operating under the same conditions regardless of size and weight?

Take the no-wind case for simplicity.  For a given bank angle, and a given groundspeed (airspeed), there is only one turn rate that will center the slip-skid ball, so the answer to the question must be "yes", assuming that "coordination" is being defined in relation to the slip-skid ball and not some other instrument such as a yaw string.

Due to various interesting aerodynamic effects that happen when an aircraft's size is significantly large in relation to the turn radius, flying with the slip-skid ball completely centered will not always be completely optimum.  Similarly, the answer to the question would be different if the question were to specify that "coordination" were to be measured in reference to a yaw string or other similar instrument located at some given point on the aircraft, rather than a slip-skid ball. For more, read "Circling the Holighaus Way" by Richard Johnson.


What is the significance of the 10,600 lbs MTOW limit?

It's nothing more than playing catch up.

If company X managed to build an aircraft for a certain mission at the lowest ever MTOW. Company Y will try to get down to that MTOW to be able to compete. Lowest is good if the mission is the same.

Check the MTOW of the Airbus A320-100 and the Boeing 737-400, to save you time, they are 200 pounds apart. But the A320-100 didn't sell well, the A320-200 did. Guess what, the 737-800 matched that weight.

Here's why:

There's something called Weight Factor.
$$
\text{Weight Factor}=\sqrt{\frac{\text{(MTOW in kg)}}{5}}
$$

The Weight Factor determines the route charges.

  This charge takes into account the distance flown and, less than proportionately, the aircraft weight.

That's why it's vital for competitors to have similar MTOW's. So they can advertise similar operating costs. MTOW is also used in airport fees.

The only interesting thing about 10,600 lb / 4,800 kg is that the weight factor is kept a tad under 10.00 (two decimal places are used). Now, is there a higher charge for a plane with WF at or above 10? I scoured the internet, there doesn't seem to be WF brackets set that way, to my dismay.

Ryanair has part of their fleet tailor-made to an MTOW of 66,990 kg (WF ~36.60) for similar reasons apparently, or they're just being cheeky.

It's also why some airlines don't choose the Extended Range. The 777-200 airframe and its ER version are the same (no auxiliary fuel tanks).

The differences are extra certification for higher MTOW, and the same engines but certified for higher thrust. Airlines can request a conversion to ER if they open routes to farther destinations.


I was in the Regional Jet industry a long time and never heard of screen burn-in as a complaint on Rockwell Collins ProLine CRTs.  You mentioned "cheaper" monitors and that may be the key.  CRTs built to an aviation TSO (Technical Standards Order) are by no means cheap.


Are these logged time assumptions correct for commercial checkride applicants?

Your question is slightly unclear, but I'm assuming the following:

You're asking about the US/FAA Part 61 requirements
The candidate is planning to take the CSEL checkride
The candidate holds a private ASEL certificate, without an instrument rating
The candidate has received some MEL training (you didn't say how much), but isn't yet rated for MEL

In that case, the answers are:

61.129(a)(3)(ii) requires 10hrs of instruction in a complex or turbine aircraft, but it doesn't say how many engines the aircraft has to have or what the training has to include. So using time from general MEL training is fine.
The FAA has said that 'double-dipping' time from private to commercial is not allowed, therefore flight time as a solo student cannot count towards the commercial certificate (Theriault (2010) interpretation).
If the pilot was receiving instruction in an aircraft that they weren't rated for then there's no way for them to log PIC time because none of the scenarios in 61.51(e) for logging PIC time apply. As you said, logging PIC as sole manipulator of the controls also requires you to be rated in the aircraft.

(This question is related.)


The air entering the first compressor stage of the SR-71's engines could be as hot as 450C while at maximum cruise conditions. If that air got any hotter, it would begin to soften the compressor blades, and this put an upper limit on the speed of that plane.


Historical gap in high aspect ratio wing transport aircraft

High aspect wings provide the best efficiency, but the current airline business model needs more than just efficiency; it also needs to keep speeds up.

Modern airlines could save on fuel by flying slower, but they would lose some business to other forms of transport or airlines that did not slow down as much. As long as fuel prices remain under a certain limit, this trend will continue. In this answer, Peter Kämpf speculates that limit might be around 200USD per barrel (originally gallon, but likely a typo).


You're right, as an exhibition piece it would had been quite an attraction. But it was not up to the Bristol company to decide her fate.

During and after the war, most British aviation development was managed by the government. The Brabazon was the result of a committee which set the goal to develop a transatlantic airliner with 1943 technology, not by a company and its technological visionaries. If you had asked people like Willy Messerschmitt in 1943 how the future airliner would look like, he would had basically described a Boeing 707: Swept wings, turbojet engines, pressurized cabin for about 100 passengers. But Government bureaucrats put the goal for the Brabazon quite differently, and the result was technically obsolete by the time it took to the air. Even before the Brabazon flew first on September 4, 1949, the de Havilland Comet had already flown on July 27, 1949 and was on its way to revolutionize air travel. Its development had started later and was directed by engineers, not bureaucrats.

When that became obvious, the bureaucracy felt too embarrassed to keep the Brabazon around. The situation was similar to Beechcraft and the Starship: Burt Rutan's 85% scale prototype was cut into pieces out of spite when it became eventually clear even for Beechcraft's board just what a turkey it was. The same fate befell the Brabazon.

But its legacy for Bristol is still very positive - without the Brabazon, it would certainly not employ as many people in aerospace as it does up to this day.


What is (or was) the "international frequency"?

The international distress frequency has been 500 kHz, since 1908.
Copious details are at https://en.wikipedia.org/wiki/500_kHz.

During the war, this frequency was used for reporting distress and for monitoring distress, by the Germans and the British.  It was also used before and after the war for this purpose, by many countries, by aviators and mariners and others.


Is there any practical benefit of the Boeing-787 to perform near vertical takeoff?

The 787 was not designed to perform such a maneuver. Any jet airliner could do this.
What you need for such a steep climb is a good thrust to weight ratio (or enough excess speed to bleed off during the maneuver). A passenger twin-jet is designed such that it can still climb with at least 2.4% climb gradient after a single engine failure during a takeoff at the maximum takeoff weight (see e.g. this answer). When the aircraft carries no passengers and only enough fuel for a short demonstration flight, it is much lighter than that (source):

Aircraft
Operating Empty Weight
Maximum Takeoff Weight

Boeing 787-9
284,000 lb / 128,850 kg
560,000 lb / 254,011 kg

As you can see, the empty weight of a 787-9 is only about half its maximum takeoff weight. And if both engines are operating, that gives you a lot of excess performance for such a maneuver. At normal weights, the 787 could not perform such a steep climb and there is also no "practical benefit" in doing so since clearing terrain must still be possible after an engine failure, which results in much less climb performance.
Also note that the aircraft was not flying at a high angle of attack. It was flying at high pitch (although not nearly vertical). The angle of attack is the angle between the average chord line of the wings and the relative airflow. When climbing steeply, the angle of attack is therefore not necessarily high.


Why don't airliners have a navigation GPS as back up in case of a pitot tube malfunction?

Airliners do generally have GPS receivers, but GPS doesn't give you the information that's needed in this case.

In AF 447, the primary consequence of the blocked pitot tubes was that the flight envelope protection system couldn't do its job properly and therefore automatically disengaged together with the autopilot. The subsequent crash was caused by the pilots' confusion and failure to realize which consequences this had for the aircraft's reaction to their control inputs.

However, what this system needs to function is not something a GPS system can possibly provide. GPS knows how fast the aircraft is moving relative to the earth, but for flight envelope protection you need to know how fast the aircraft is moving relative to the surrounding air, which GPS doesn't have any way of knowing. The differences between these values is caused by wind and can be pretty large. It would be a recipe for disaster to let the computer limit what the pilot can do based on an arbitrary assumption that there's no wind. (And, as Terry comments, there's an additional difference caused by air pressure).

If I remember correctly, the AF 447 investigation concluded that the pitot tubes had thawed and began functioning properly well before impact; it was not the loss of airspeed indication that prevented the pilots from salvaging the situation. By this time the pilots were confused and thought the airspeed indication was still malfunctioning because it showed a much slower speed than they thought they ought to have -- whereas in fact it was working perfectly well.


Why are the throttles of aircraft such as the Twin Otter placed on the overhead panel?

I think it was for two reasons:

It makes for straight path for the controls to reach the engines, as all of these are fly by cable. Many of these aircraft where also designed for harsh climates, so I imagine it's an advantage to have less pulleys and other things which might rust and require maintenance.
There is very little space to place the throttles further down, especially with the control column mounted on the DHC6 Twin Otter where it is. If you did want a pedestal, you'd have to seperate the control columns, requiring further mechanical components, and you'd have to route the engine cables upwards, both of which would be undesirable.

As you mentioned, there are downsides. Commonly mentioned ones are:

It is not particularly comfortable to have you arm raised for an extended period of time, and you lose some sensitivity in it.
You hope that the other pilot used his deodorant that morning.

Other somewhat similar aircraft which use this configuration are the PBY Catalina and Grumman Goose. Another one is the Avro York heavy transport aircraft.


Why does a pilot bank up to 5 degrees into the operating engine following failure of the other engine?

The 5 degrees of bank is to create a side slip component that offsets the skewed thrust line created by the asymmetric thrust, and the rudder input made to counteract the asymmetric thrust.

You have the live engine on one wing that wants to make the airplane turn.  You apply opposite rudder to stop the turn.  With the rudder moment pushing sideways, you end up with a resultant thrust line that is offset, and the airplane proceeds forward with a lateral skew toward the dead engine even though you think you're going straight.
By banking into the live engine, bank angle makes the airplane want to side slip toward the down wing, which is in the opposite direction to the skew effect mentioned above.  The 5 degrees of bank is roughly what gives the necessary amount of side slip tendency.  Close enough in other words.

The result is that you will be flying with 5 degrees of bank, but actually proceeding straight through the air.  The skid ball will be offset into the bank because you are actually still in coordinated flight and the offset location of the ball is the true "centered" location.


What is the relationship between blade inertia and rotor kinetic energy?

The relationship between blade inertia and rotor kinetic energy is:

$$K = N\frac{1}{2}I\omega^2$$
$$I = \int mr^2dr$$

Where:

$N$ is the number of blades
$I$ is the moment of inertia of a blade
$ω$ is the rotational velocity (rotor rpm)
$m$ is mass
$r$ is distance from hub along the blade

For a fixed RPM increasing the moment of inertia of the blade increases kinetic energy of the rotor. An increase of the moment of inertia can be obtained by increasing the mass of the blades (inefficient, rotor gets heavy and requries more power from engine, less payload, etc.) or by placing relatively small masses at the tip of the blade.


What would cause a non-zero indicated airspeed reading on the ground?

A mechanical blockage inside the airspeed gauge could prevent the needle from dropping all the way back to zero -- assuming the aircraft had exceeded 200 KIAS in the first place.
Whether this or the pitot-related failures in the @CamilleGoudeseune answer, the pitot-static unit, airspeed indicator, and altimeter (also connected to the static port) should be checked and repaired as needed by a qualified person.


Modern commercial airliners have 2 different wind shear protection system:
1) predictive wind shear warning system
2) reactive wind shear warning system.

These systems work independently. PWS (predictive wind shear) works with weather radar. Reactive wind shear works with FAC ( Flight augmentation computer)

Basicly PWS can be switched ON and OFF from the WX-Radar  panel and it has some prerequisite for working :
Ground speed should be above 30 KTS, WX-Radar should be ON, At least one engine working etc. (may differ with different types).

PWS scans 5 NM ahead from 0-2300 ft and 1500 ft below according to phase of the flight. It works like a doppler radar. It scans the movement of air mass in front of you and "predicts" something goes wrong and warns you according to how bad is the situation. Doppler frequency will shift significantly in case of a microburst so PWS will catch this shift and warn pilots with amber or red cautions.

Reactive Wind shear system works with on board computers that takes real time data from all sources. This system will be active generally from 50 ft 1300 ft. (may differ)

Reactive Wind Shear basiclly monitors aircrafts energy level. For Airbus; FAC is responsible for that.
In computing the energy level FACs use different data from different sources: ADIRS - air, ground speed, vertical speed , slope. from other sources - wind gradient, vertical wind etc.

It will be active when the a/c energy level goes below predetermined threshold. It will alter from amber to red if your energy losing trend is faster.

You can read this document from airbus includes many general aviation information for more details :
http://www.airbus.com/fileadmin/media_gallery/files/safety_library_items/AirbusSafetyLib_-FLT_OPS-ADV_WX-SEQ02.pdf

Hope it helps.


How do non-US pilots get the hours necessary for an ATP?

Under the rules of ICAO Annex 1, Personnel Licensing, you don't need an ATP License to fly as second in command (SIC) on a commercial aircraft required to be operated with a co-pilot. A commercial pilot license (CPL) is sufficient to be SIC on an aircraft that requires to be operated by more than a single pilot.

And since 2006 ICAO have defined a Multi Crew Pilot License that also allows a pilot to be second in command on a commercial air transportation multi-crew aeroplane.

The  ICAO website about Multi-Crew Pilot Licence (MPL):

  The MPL allows a pilot to exercise the privileges of a co-pilot in a
  commercial air transportation on multi-crew aeroplanes. It provides
  the aviation community with an opportunity to train pilots directly
  for co-pilot duties. It is a new licence that has been introduced in
  addition to the existing pilot licences defined in Annex 1 — Personnel
  Licensing.

  The licence focuses on ab initio airline pilot training.
  MPL training and assessment will be competency-based and involve a
  multi-crew environment and threat and error management from the onset.
  It provides for greater use of flight simulation training devices and
  include mandatory upset training. At this stage, only aeroplanes are
  considered for this new licence. The details of the requirements for
  the licence are contained in Annex 1 — Personnel Licensing and in the
  Procedures for Air Navigation Services — Training (PANS-TRG). These
  documents outline the minimum international Standard for the
  implementation of the MPL by any State; they can be purchased directly
  from ICAO through the Document Sales Unit.

In Annex 1, the requirements are laid down for the MPL. One of the requirements says:

  Experience

  2.5.3.1 The applicant shall have completed in an approved training course not less than 240 hours as pilot flying and pilot
  not flying of actual and simulated flight.

The MPL, combined with a type rating, will get you to the right hand seat of the aircraft of choice.

So it's likely there are 250-to-500-hours commercial pilots flying Second In Command (SIC) into JFK. With experience in Beech Bonanza's, Cheyenne/Seminole, maybe CitationJet, a lot of simulator time and a couple of hours in a B777.

To answer your title question, in many countries pilots get their ATPL after building hours as SIC flying with a CPL or MPL within an airline training scheme.