Is there always a stall if you exceed a specific angle of attack?

Yes, stall depends only on angle of attack. However

  Does this mean, that, at whatever speed you are flying (i.e. 500 knots), you would stall if you go on a climb angle of more than 16°?

No. Climb angle and angle of attack are completely different things.

This image from How It Flies shows the four different angles involved. Pitch is the angle between aircraft floor and horizontal, wing incidence is angle between aircraft floor and wing¹, angle of climb is angle between direction of flight (a.k.a “flight path” or “relative wind”) and horizontal and finally angle of attack is angle between direction of flight and wing.

The image shows that angle of attack + angle of climb = pitch + wing incidence.

Up to stall, lift depends approximately linearly on angle of attack and square of speed (and on air density). In straight flight the forces on the aircraft need to be balanced, so angle of attack will be such that they are. If you increase pitch, the angle of attack will increase, which will cause unbalanced force, which will cause upward acceleration and that will increase the climb angle at the expense of the angle of attack again.

So if you go on a climb more than 16°, the angle of attack will not significantly differ from what it is when you fly level at the same speed.

  I am just wondering, since, if you fly in the microsoft flight simulator with a big jet, you can have an angle of attack of 30° and more, and not stall until you get to the stall speed.

No, you can't. You, however, can climb at 30° or more, for a while before you run out of speed. Which at low altitude is actually quite long; the jet engines are designed to have enough power at high altitudes where air is much thinner and to allow taking off when one engine fails late in the take-off roll. Therefore low with all engines operating at full power you have quite a bit of extra thrust available.

Also note, that stall does not mean loss of all lift. You only loose part of it. A significant part, but not all. Stalled aircraft is still controllable (though ailerons effect is reversed) and some aircraft (though this would be fighters, not airliners like 747) may even have enough lift and thrust to maintain altitude when stalled.

¹ Specifically, the zero-lift line of the wing. This coincides with the chord of symmetric wings, but cambered wings have it tilted up.


What are the concerns and consequences of an overweight landing?

Two things:

Loads on the landing gear. This can be alleviated by carefully touching down, but you never know what exactly will happen in the next landing, so better don't count on it to be smooth
Deceleration distance: The higher mass requires a higher approach and touch down speed (higher by the square root of the mass ratio between your actual mass and the maximum certified landing mass). Now you have more mass and more speed, but the landing strip and the airliner's brakes are still the same. The risk is that you overshoot the runway with an airplane full of fuel or that you overheat the brakes (which will result in their failure, and again an overshoot). Since the kinetic energy is proportional to mass times speed squared, the energy which needs to be absorbed by the brake goes up with the square of the mass increase.

If the selected runway for your overweight landing is long enough and the weather is calm (so a smooth landing is easier), an overweight landing is not such a problem.

Now let's look at the 777-300ER in detail. I use the figures from Wikipedia, because the manufacturer's site is trying much harder to hide the relevant data. The MTOW (maximum take-off weight, which is actually a mass) is 351,534 kg, and the maximum landing weight is 251,290 kg, about 100 tons less. Now let's assume that taking off and returning to the airfield uses 5 tons of fuel, so the mass ratio is 1.379. Therefore, the approach speed has to be 17.4% higher and the total kinetic energy at touchdown is higher by a factor of 1.9 compared to the case at maximum allowable landing weight.

If we now assume that speed is reduced linearly during the landing run and that the wheel brakes will just absorb as much energy over time as in the case at maximum landing weight, the deceleration needs to be lower by the mass ratio, so the aircraft decelerates with only 72.5% of the deceleration at maximum landing weight. To shed its kinetic energy, the landing run will take longer by the increase in kinetic energy, i.e. 1.9. Since the average speed is also higher by 17.4%, the landing distance will be higher by a factor of 2.233 or 223% of the landing distance at maximum landing weight.

This neglects that the heating of the brakes is an instationary process, so you cannot simply brake with the same intensity for more than twice the time they were designed for. But this little estimation should illuminate what impact a higher landing mass has on the energy and distance involved.


What are the dimensions of the A320's wingtip fences?

Dimensional information can be found on Airbus's Airport and Maintenance Planning Documents for the entire product range.

You will have to do a little digging and calculation to find the sizes of the wingtip devices but they are there.

Specifically, on the A320, subject 2-3-0 lists the height of both of the bottom and top of the wingtip fences relative to the ground, and 2-2-0 provides dimensions from the top.


Why do control towers have tilted glass panels?

I'm pretty sure that has to do with reflections especially at night.

If you have ever stood between two mirriors you will understand the infinity mirror.

Light bounces back and forwards between the mirrors so when you look into them it appears like the scene goes on forever.

Window glass reflects a certain amount of light, like a mirror. In a control tower, where windows are all around you, if the surfaces of the windows are parallel you get that infinite mirror effect.

During daylight hours this can be seen as glare, but at night when you are trying to see that navigation light on Flight 594 amid a sea of runway and taxi-way lights, having your vision further confused by a myriad of reflections from the back window would be a bad thing. Further, since the room is a glass box, light can bounce all the way round the room. It would be quite possible to look off to your right and think so you see an unidentified aircraft approaching, but be actually seeing some truck's lights on the hill a couple of miles away over your right shoulder.

Tilting the windows outwards means the reflection angle is towards the ceiling, which is generally painted black, and the effect goes away.

Further, tilting out means you can no longer see your own reflection, or reflections from other lit workstations in the window. Ever tried looking out of a window at night into the dark and only see your own ugly mug staring back at you, then tried to move your head to the side to see around yourself. LOL

Of course, for all this to work, the ceiling should be dark.

A few other reasons include, less affected by rain, fewer refraction effects, and external reflections. Bonus feature, less greenhouse effect and AC bills. Downside... darn hard to clean.


What were/are the military designations of the JT8D and PW4000?

Two versions of license built military JT8D is called RM-8A and RM-8B.
PW4062 is a military version of PW4000 used in Boeing KC-46 Pegasus.


How safe is the Boeing 737-800 in high winds?

Extremely safe.

Firstly, your pilots will have access to much more detailed and real-time weather information than you can get. They want to get home safely as much as you do, and will not fly if it is not safe to do so.

If the wind is coming from straight ahead, there is no maximum limit, which is good as aircraft takeoff and land into the wind whenever possible. If the wind is coming from the side - known as a crosswind - the limit in a 737 is about 36 knots/19 mps (the specific number can vary but that's a guide). The reason for this limit is to avoid the winnd blowing the plane off the side of the runway. So if the wind is that strong, hopefully the runway faces into wind, otherwise your pilot may have to delay the takeoff until it calms a bit.

Once the aircraft lifts off the ground, the wind speed is irrelevant (except for navigation purposes). Imagine a fast flowing river. Placing your canoe into the river when it is at such speed is difficult, but once you are in the middle of the water it is smooth as silk. The transition from ground to cruising altitude is similar. The initial climb will probably be turbulent but the aircraft is built to sustain more than nature can throw at it. Once at altitude the wind speed will almost certainly be much more than 100 knots - but just like the fast flowing  river, if you close your eyes it will feel nice and smooth.

You should only cancel your flights if you want to throw away your money. Otherwise just try to relax, and understand that many airline delays that you hear of are caused by a pilot choosing safety over schedule.


Can an aircraft or helicopter run into its own wake vortex?

Helicopters are not easy to fly - whether full-scale manned aircraft or RC models. I would bet that your issues are more related to pilot error than any fault of the machine (other than the fact that it is a helicopter, and inherently unstable).

That said, almost any aircraft can be maneuvered in such a way as to encounter its own wake, and the helicopter is no exception. In fact it's much easier do to this in a helicopter than in a fixed-wing aircraft: A condition known as "settling with power" (or "vortex ring state") can occur when a helicopter descends into its own rotor wash, e.g. by descending directly vertically in calm air. The results of such an encounter can be "unpleasant" - a number of helicopter accidents have been attributed to this sort of encounter.


What is formula for induced drag in stalling regime?

That formula describes the "lift-induced drag" for a planar wing. Lift-induced drag

As the definition implies, this drag is induced by the generated lift, the effect of stall (flow separation) is not contributing to this drag component.

Therefore, there is no other formula for the stalled regime.


Are any jet engines used in combat aircraft water cooled?

Jet engines are cooled and temperature managed by the mass air flow itself which is used to surround and limit the boundaries of the flame, keeping it away from the burner can walls, and dilute the heat of the flame as it passes to the turbine (only a minority of the mass airflow's oxygen is actually burned - which is why afterburners work; there's lots of leftover oxygen to work with).

If you're talking about using a closed liquid cooling system with heat exchangers taking heat from the burner can and turbine somehow, well, I've never heard of a water jacketed burner can, and how you could use liquid in a closed system to cool a turbine, who knows.

Liquid cooling was used in the past as supplemental cooling to increase available power by spraying water directly into the mass flow as mentioned here, but in that case the water is a consumable.


Why doesn’t the A320 family suffer from the same design constraints regarding engine placement/landing gear length as the Boeing 737 family?

So how does the A320 design address this? Longer landing gear with attachment points further outward on the wing [...]?

Yes, the A320 has a longer and therefore wider landing gear. You can find general aircraft dimensions in the Airplane Characteristics for Airport Planning documents.
Airbus A320-200: 7.59m wide landing gear

Boeing 737-800: 5.72m wide landing gear

The same document also lists the ground clearances at different points. At MTOW (max. takeoff weight) or MRW (max. ramp weight), the ground clearance
below the fuselage is
A320: 1.72m, 737-800: 1.30m
and below the engine nacelle it is
A320: 0.57m, 737-800: 0.48m

Sources: Airbus, Boeing


Do jet fighters have air conditioning systems?

Yes. Fighter aircraft have air conditioning systems. In general, they are called as Environmental Conditioning Systems (ECS). Their primary functions (as far as cockpit goes) include,

Cockpit Pressurization

Heating/Cooling/air-conditioning

Windshield anti-fog/anti-ice

The systems usually use conditioned engine bleed air or this purpose. The cockpit air conditioning is usually managed by the pilot. For example, in case of F-15, the following system is available:

Image from f-15e.info
with the available controls listed as,

TEMP switch: A three-way switch to manage cockpit temperature. When AUTO, cockpit temperature is automatically maintained at the temperature selected on the TEMP knob. When MANUAL, cockpit temperature may be changed with the knob, but not maitained automatically. When OFF, it shuts down off ECS air.
TEMP knob: A rotary knob to set the cockpit temperature.
FLOW switch: A three-way switch to select air flow. MIN, MAX and NORM settings are available for minimum/maximum/normal air flow, respectively.
FLOW knob: A four-position knob to set the air source. When BOTH, bleed air is supplied from both engines. When L ENG or R ENG, bleed air is supplied from the left/right engine only. When OFF, no bleed air is supplied.

The following image shows the other controls associated with ECS.

Image from f-15e.info


What is the function of the holes in splitter plates?

Do the holes in splitter plates reduce the boundary layer?

Yes. Suction is applied to remove the slow-moving layer of air close to the surface, so the air entering the intake has as uniform a speed distribution over the intake cross section as possible. That this air is used for cooling before being dumped overboard is sensible, but if cooling were the single purpose for sucking it in, then better and more efficient designs exist.

The boundary layer which has built up on the forward fuselage is removed by the splitter plate itself. The perforation is only for removing the fresh boundary layer which has built up over the upstream length of the splitter plate.

On some spike intakes the designers even implemented boundary layer suction on the intake cone, ducting the flow through struts in the intake to the outside of the engine. Even this complex arrangement seems to be worth it because it improves the efficiency of the intake and allows to widen its operating limits. From this article of the Airspacemag web site:

  The SR-71 inlet rids itself of boundary layer air by sucking it in
  through slots on the spike and passing it through ducts that exit the
  nacelle.

The airflow schematics in the picture below call this particular flow "centerbody bleed". Note how it is reversed at low speed in order to suck more air into the engine while it is used to dump the boundary layer air as soon as intake pressure rises above ambient pressure at higher flight speeds.

SR-71 engine airflow patterns (picture source)


Why does it take so long to develop a passenger aircraft?

It's similar with military aircraft. In a mature field it becomes ever harder to create something that is clearly better than what we have already.

Since every new development costs so much, the consequences of failure are immense. Therefore, management will try to lower the risk of failure which again drives up development cost and time. It is a self-reinforcing spiral.

Add to that the fact that we now have only two major civil aircraft producers which both are heavily backed by their respective governments and are too big to fail. This creates political interference which makes major decisions even more complex and precludes bold, risky decisions. Only the most safe* option will be chosen after years and years of deliberations.

And I refuse to believe that we don't know enough yet in aerodynamics or materials science. When a wing test lets the wing break at a load factor of 1.54 (where 1.5 is the goal) on the first try, we are pretty good already. Same for performance: New models hit their predicted fuel consumption within 2%! And regarding the many subsystems: COTS. Of course, if you insist on re-inventing the wheel all over again for a new airliner, then those 10 years are acceptable.

* "Safe" meaning the one promising the highest bonus to management for the time they hold their position, and with their current state of incomplete knowledge. Sadly, the ethos of companies like Newport News Shipbuilding, whose motto was: 'We will build good ships here — at a profit if we can, at a loss if we must, but always good ships.' has been lost to the Harvard MBA culture with its focus on short-term results.


Why can’t aircraft use GPS to generate the IAS, instead of using pitot tubes?

To answer the other part of your question, in a scenario where you lose all 3 speed indications, you are left with pitch and power.  If you know the airplane really well and are sufficiently skilled at flying, this should be enough.

For example if you've been flying some jet for a while you will know that at Vref on a 3 degree glide slope flaps and gear down you will have an fan RPM range of say 60% at lighter weights and 65% at max landing weight.  So when on the glide slope you just hold the pitch attitude that keeps you on slope and keep the power there and the speed will take care of itself, within reason.

Same if you're just flying around in level flight.  Just holding the pitch attitude and setting power at the value you're used to will keep your speed somewhere in the ballpark.  In fact, at the extremes, it's quite easy to tell the difference between 250 kt and 330 kt just from the sound (the roar at Vmo is unmistakable).

On a descent at idle, you'll know from experience that the pitch attitude is, say, 15 degrees below the horizon at 200 kt.   So you just fly the attitudes you know will work, with power that's appropriate to the speed range you want, and you'll be close enough not to fall out of the sky.

On top of that, the manufacturers all provide pitch/power setting tables in their QRH procedures that can be used to maintain speeds close enough to avoid falling from the sky (fallout from some of the clear-air pitot icing incidents).

I know personally of an Atlantic Southeast Airlines CRJ crew that lost all 3 airspeed inputs from ice crystals, used their pitch/power skills to manage things on decent until they got their speed indications back when they were lower.  But they would have had no problem landing the plane with no airspeed if it came to that, and that was before there were QRH pitch/power tables.

The Aeroperu guys were unfortunate in that they went into brain-lock and became disoriented in the darkness.


A deconfliction service is a specific type of air traffic service.

Normally, outside of controlled airspace, air traffic controllers do not alert pilots of potential encounters with other aircraft (conflicts).

However, there my be other services offered outside of controlled airspace, typically these are Flight Information Services (FIS).

In the UK, four air traffic services are distinguished outside controlled airspace: Basic Service, Traffic Service, Deconfliction Service and Procedural Service

  A Basic Service is an ATS provided for the purpose of giving advice
  and information useful for the safe and efficient conduct of flights.
  This may include weather information, changes of serviceability of
  facilities, conditions at aerodromes, general airspace activity
  information, and any other information likely to affect safety. The
  avoidance of other traffic is solely the pilot’s responsibility.

source: UK Flight Information Services CAP 774, February 2015

Note the last sentence.

The deconfliction service is defined as:

  A Deconfliction Service is a surveillance based ATS where, in
  addition to the provisions of a Basic Service, the controller provides
  specific surveillance-derived traffic information and issues headings
  and/or levels aimed at achieving planned deconfliction minima, or for
  positioning and/ or sequencing. However, the avoidance of other
  traffic is ultimately the pilot’s responsibility

Again, note the last sentence.


Did Kai Tak have a straight-in approach to runway 13 for higher-performance aircraft?

did Kai Tak have a straight-in approach to runway 13 for use by steep-approach-certified aircraft?

During the 1990s I regularly flew the Hong Kong IGS approach in 747s. At that time, to the best of my knowledge, there was no straight-in approach to runway 13.

  only the best of the best pilots were allowed to shoot the bent approach to runway 13, and only after extensive simulator training for that specific approach, and even they had considerable trouble with it, even in good weather.

While the above might have been true for some carriers, it was not true (Wikipedia to the contrary) for the two 747 carriers I worked for. Cathay Pacific might have had some such requirement as that was their home base.

Go to https://terryliittschwager.com/talking-of-flying.php#kaitak for an account of my first time in.

Wikipedia has another error or at least a poor choice of words IMHO when they say that upon reaching the checkerboard hill you started the turn toward the runway. if you look at the approach plate, you'll see the turn starts well before the checkerboard. The rule was that you had to have the checkerboard in sight ahead before starting the turn. If you didn't it was missed approach time. Fortunately I never had to do that.

  to the eternal gratitude of non-masochist pilots everywhere) had a hideously difficult and dangerous approach

I never considered the approach dangerous. Challenging, yes, but not dangerous. And I'm really not a masochist or at least I didn't think of myself as such. After you got used to it, it was fun!


Why, until recently, were smooth nose sections not popular?

Because it's bloody difficult to make the curved shapes out of the materials used until recently, with the technology available at the time.

The few aircraft that had it in the past generally were very expensive and labour intensive to build, compared to competitors, and therefore not economically successful.
Now, with improved manufacturing techniques and materials, plus the rising cost of fuel, it's becoming ever more viable and more such are appearing.


What happens when a temporary pilot certificate expires?

According to this AOPA article, you can request an extension online through the FAA's Airmen On-Line Services.

You also can look up your current status here:

http://www.faa.gov/licenses_certificates/airmen_certification/new_verification_info/

In my case, this was updated about a week before my card arrived in the mail.

You can also see what date's submissions they have processed here:

http://www.faa.gov/licenses_certificates/airmen_certification


What are the adverse effects of keeping the PACKs on the A320 running with the LP air conditioning unit connected?

Latest FCOM, after revision 24 of section 3.01.21, contain the explanation:

  AIR CONDITIONING WITH LP GROUND UNIT

  Do not use conditioned air simultaneously from packs and LP ground unit (to avoid chattering of the non return valves).

The non-return valves prevent air in the mixer unit to return into any source in the case this source delivers air at a lower pressure, or doesn't deliver air. Valves are the one-way separation between the air generation section and the air distribution section:

     Source

If the LP ground connection is used while the packs are ON, pressure will be comparable on both sides of the valves. Valves can start chattering instead of being stable in the open position. While pressures compete, air from the mixer unit can return to the packs.

Damage can occur, as described in this 1991 incident (air conditioning duct and non-return valve damaged).


Why are cambered airfoils used for horizontal stabilizers in some designs?

It's done to get a little more lift coefficient, and hence more tail downforce power, at low speeds and there is a drag penalty to take depending on how much camber.  The Zenith STOL family are the extreme example, and being draggy flying lunchboxes anyway, the penalty is minor in relation to the benefit and allows a smaller, lighter tail unit than would be needed otherwise.

Some high performance and transport aircraft have cambered airfoils for the tail but the amount of camber is subtle (a bit more curvature on bottom than top) and you can only tell if you can see the actual airfoil profile, or examine the surface up close.


Terms fist, to avoid any misunderstandings:

What you call cuboids is normally called a wing spar. It consists of spar caps for the tension and compression loads and a web between the caps to transmit shear. And yes, it runs all the way from one wingtip to the other.

The spar carries the bending moment which has its maximum at the center and is zero at the tips (unless you use winglets). The more distance there is between the two spar caps, the lighter the spar can be built, so a thick mid-wing airfoil helps. Your choice of the NACA 64₃618 is a good start. I would advise, however, to taper the wing to something like a NACA 63₃412 at the tip. Thinner airfoils have lower minimum drag and higher maximum lift coefficients which helps to avoid the tip stalling first.

Or you move to newer airfoils which have been optimised for longer laminar boundary layer runs. Since you plan to use carbon/epoxy for the wings, you might take advantage of the exceptionally smooth surface this makes possible. The NASA contribution is of course the NLF series, NLF standing for natural laminar flow. The NLF(1)-0416 or the NLF(1)-0215 would be possible candidates. Even better designs might be possible when you search for modern glider airfoils; however, the published ones generally are at least 30 years old. Glider airfoils are optimised for minimum Reynolds numbers of around 1 million; when used in a GA aircraft this might be a bit conservative but could fit well to your low speed requirements.

The ultimate step could be to design your own airfoil. Take my glider recommendation and use XFOIL to tweak it to what you really need.

One last word on your choice of flaps:

When the inboard span uses powerful slotted flaps, their increased circulation will change airflow at the outer wing in such a way that the outer wing will stall before the inner wing had a chance to demonstrate it's lift potential. Either stay with plain flaps (for which the HQ-17 was designed - make sure you calculate it with a positive flap deflection at slow and negative at fast flight speed!) or add slats to the outer wing. In order to keep complexity manageable, I would recommend to use plain flaps and flaperons over the full span.


How can I find my grandmother's OLD instrument rating documentation?

The FAA has an airmen inquiry search portal. I put Nathalie Brown and came up with Nathalie Myrtle Brown with the following details:

Certificate: PRIVATE PILOT   Date of Issue: 11/25/1968
Ratings: PRIVATE PILOT
AIRPLANE SINGLE ENGINE LAND
AIRPLANE MULTIENGINE LAND
INSTRUMENT AIRPLANE

As @FredLarson points out in comments the date supplied seems to be the last change to their database, i.e. address, name or addition of rating, so that means she must have gotten all of her certificates at or before the 25th of November, 1968.
This is a start, but it doesn't give you real dates. If the FAA has that much information they should have a lot more, to get details you should contact the airmen certification branch. I'm not sure what hoops you have to go through, maybe prove you are family, etc.
There is a big database of pilots from the FAA search portal, but it is not complete - your grandmother wasn't in it for example, and there's no dates of ratings anyway. Maybe the FAA can get you access to a better airman database with more of those records, it's possible they simply don't exist anymore though, you'd have to ask.
If she has personal effects left then her pilots certificate or other details may be there, certificates used to be paper, probably folded up. Really useful would be her logbook, which would be a record of every flight she made, there would be endorsements in these which would be useful in learning when she achieved her ratings.


How wide is the cone of confusion above a VOR and NDB?

The value +/-40° is correct, but need to be interpreted. The primary reason of the existence of a "silence" (confusion) cone is a design choice to increase navaid range. Range and "isotropy" are antagonistic.
However, when the aircraft approaches the confusion cone, say at 45° elevation, while flying at 9 km above the station, its slant distance to the station is about 13 km. Even with a small apparent power (say a few RF watts), the radio link being not attenuated by obstacles, is still very good. It should not prevent the signal from being demodulated.
There is a second phenomenon, which is more critical for a D-VOR: The Doppler shift is created by the antenna scan in the horizontal plane only, and is maximum when the receiver is on the station plane. As the relative elevation increases, the apparent displacement in the direction of the receiver is reduced. This reduction of the distance results in a reduced apparent velocity toward/away from the receiver, hence a smaller Doppler shift.

Without the correct shift, -480 Hz to +480 Hz, bearing determination is inaccurate (for a detailed explanation of VOR principles, see this answer). For conventional VOR there is a similar problem but related to the amplitude.

Detailed case: D-VOR
A VOR radiates a signal that can be interpreted in the horizontal plane, so the system is designed with antennas radiating horizontally. There are two types of VOR, the most modern is the D-VOR (Doppler VOR). A common antenna for D-VOR is the Alford loop antenna which is horizontally polarized:

Left: Source, right: Source
The D-VOR antenna system consists of a circular array of antennas:

Source
This array has a radiation pattern similar to this in the vertical plane:

How to interpret:

The straight lines are elevation angles, 90° being the zenith. The brown circles are a scale for power radiated, the large circle is the power measured in the direction where it is maximum. The next circle is where power is only -3dB of the maximum. Using decibels to measure ratios is frequent when working with radio signals because this is a logarithmic scale. -3dB is half the power, -6dB is 1/4 of the power, etc.

The red curve is the radiation power curve of the VOR for any vertical angle. It is maximum around 30° and minimum at 90°. For 60° its about -20dB which is a ratio of 1/100th only.

VOR cone of silence/confusion is where the signal is too small to be correctly interpreted by the VOR receiver, and you can see there is a strong signal fall around 50°-60° (that is 30°-40° from the VOR zenith)

As visible, power is mostly radiated to one side, the other side of the antenna array radiates only a parasitic power. This is due to the way the D-VOR works: Interfering pattern between all the antennas of the array. Power is destructed on the right side of the diagram, while it is cumulated on the left side.

The interfering pattern is rotated electronically around the vertical axis at 30 rounds per second (1,800 RPM, 30 Hz), so the antenna actually radiates power in an annular volume (donut).

Doppler cone of confusion
Specific to the D-VOR, due to the way this VOR works:

In the conventional VOR relative bearing is obtained by sensing the phase difference between a reference modulation (FM) and a varying modulation (AM) which depends on the direction the VOR antenna is currently pointing to.

In the Doppler VOR, the varying signal is actually obtained by electronically moving the center of the antenna array. This creates a frequency shift that is equivalent to the AM modulation of the C-VOR, but in frequency (and the D-VOR electronically "rotates" in the other direction so that the inversion between AM and FM modulation is not visible, ensuring compliance between C-VOR and D-VOR with the receiver).

However the Doppler effect can be sensed only when the receiver is on the same plane than the electronic "displacement", i.e. the horizontal plane. When the receiver is located too close to the VOR zenith, the frequency shift becomes small, and cannot be sensed correctly. This is why, even with an isotropic antenna, the system cannot work at high relative elevations. So there is actually no point to have an isotropic antenna for the D-VOR.

C-VOR and NDB
A conventional VOR (C-VOR) works with a vertical antenna which radiation pattern is naturally similar to the one above without the need for interferences. The antenna actually rotates physically.
NDB use long wire antennas of many kinds. The power is radiated with nearly no particular preference (omnidirectional antenna), but the radiation pattern is still similar to the C-VOR one, except that there is no need to rotate it. The donut volume is obtained with the antenna stationary.
As the NDB is omnidirectional, the energy in the horizontal plane is not focused as strongly as for the C-VOR and D-VOR. However NDB range is still reasonable because:

NDB uses the LF/MF portions of the radio spectrum which are less subject to propagation losses.

NDB receiver doesn't require a strong signal to locate the beacon, as simply detecting the carrier is in theory sufficient.

Why is that done this way?
You may ask why not using an antenna (or an antenna array) with a circular radiating pattern radiating the same power in any vertical direction. Such "isotropic" antennas exist in practical.
The reason is the same than for rotating the antenna: It's to concentrate power in one direction, to increase the range. In technical terms this is to increase the effective isotropic radiated power (EIRP).
A good similarity is the one of a light bulb and a torchlight:

A light bulb has an omnidirectional radiating pattern, it lights up in all directions, but the power received at a distant point is limited (unless the light bulb is a very powerful one).

A torchlight focuses light in a small solid angle, multiplying by a large factor the intensity in the privileged direction. A high intensity can be perceived in this direction without using a huge power, and the range is increased at equal power. However to scan all points in space, the torchlight must be rotated.


Do afterburners use excessive amounts of fuel?

Yes the specific fuel consumption of the afterburner, lbs of fuel used per lb of thrust, is much higher than the core engine.  This is because the fuel is being added to a part of the engine where the air is less compressed, so the energy conversion is a lot less efficient. The bright orange flame coming out the tail pipe when in reheat is pretty much all that un-oxidized carbon fluorescing - wasted energy. See this article.

Fighters use reheat because all that extra power is available with minimal extra weight (the weight of the burner and additional fuel), but they can only exploit that power for short periods if they want to have decent range or endurance, so they are generally used for dashing somewhere, or to assist with maneuvering, or taking off with a heavy load.


Did the "feeler" ailerons of the B-52A-F make air-to-air refueling easier than with the B-52G/H?

The earlier variants were indeed easier to handle. The H-variant featured an independent spoiler panel for finer control to make it easier:

In practice, the short fin combined with spoilers-only lateral control induced a tendency to Dutch-roll and low level handling was more sensitive than on earlier B-52s. Raising the spoilers also caused a slight pitch-up movement which was considered a real problem for inexperienced pilots when flight-refuelling. A later modification (used on the B-52H) the 'Airbrake 1' position gave a 10 degree independent movement on the outer spoiler sections for minor corrections, particularly during flight refuelling. The spoilers were powerful control devices. A B-52G from Robins AFB (28th BS) was landed using only throttles and its spoilers after total failure of the elevator controls. This feat won Crew E-21 the Mackay Trophy for 1982. [emphasis mine]
— Davies, Peter E., Tony Thornborough, and Tony Cassanova. Boeing B-52 Stratofortress. Crowood, 1998.


It's fairly common for cargo, freight, and mail to be carried by aircraft - particularly for high value or priority cargo.

For example Royal Mail (the primary British mail service) uses short haul flights for distances of less than 100 miles (London Stansted to East Midlands Airport), along with around another 10 flights within the UK, every night.

These flights are used for priority (next day) mail, but will be filled with "cheaper" mail if necessary.

It all depends on the value of the cargo and the speed which it needs to travel, and aircraft only tend to be used where it is profitable to do so (ie where the cargo needs to travel fairly quickly and they can charge a high price to justify that).

Generally trucks will be used for shorter distances (<500 miles) for low value cargo, and for longer distances for heavier cargo or cargo which does not need to travel quickly.

http://www.eastmidlandsairport.com/emacargo.nsf/content/customer_royalmail

https://en.wikipedia.org/wiki/Royal_Mail#Fleet


How does experienced pressure vary with airspeed?

1) Pressure is simply a force divided by an area, so yes: The dynamic pressure experienced by a forward-facing surface will, in an incompressible flow, vary with the square of the speed.

2) The dynamic pressure increases dramatically as one approaches the speed of sound, once going faster than mach one the pressure will begin to decrease. The trans-sonic phase (around mach one) is difficult to describe and can depend on the airflow around the body - but in many cases it can be quite stable.

-edit-
For the second question here's a couple of links that can provide more information:

Transonic flow around a rocket
NASA history of transonic research


What does ATC do when a VFR flight in the mode C veil has a malfunctioning altitude encoder or transponder?

A lot of this has to do with whether or not you're talking to ATC.

If you're talking to ATC and your Mode C disappears or goes insane they'll ask you to report your altitude (and if your Mode C altitude reporting is wildly off they'll probably tell you something like "Stop altitude squawk - altitude differs by 500 feet". This is your cue to take the plane to an avionics shop and have the system checked/serviced, and not to attempt to enter B or C airspace, or fly above 10,000MSL, until its fixed.

In most cases ATC will continue to work you in the system until you are clear of the Mode C veil (possibly expediting your exit if having no altitude readout on your target is messing up their day) because it's better to be talking to you than not.

If you're not talking to ATC things get a bit more complex:
If your Mode C altitude readout is missing ATC will generally report you as "traffic, altitude unknown" to other aircraft and apply lateral separation exclusively (nobody is allowed within the minimum lateral separation distance of your target unless they have you in sight and can maintain visual separation). If/When other pilots spot you ATC will usually ask them for your type and altitude so they have some idea of who you are and what you're doing.

If your encoder or transponder is malfunctioning and reporting an incorrect altitude that's substantially more dangerous: ATC has no way of verifying your altitude other than asking you (or another pilot), so they'll be maintaining separation based on an incorrect altitude. This is why even VFR aircraft equipped with Mode C need an encoder check.
In this case ATC will find out about a malfunction when you're called as traffic to someone and they respond with "Is that my traffic above/below me?"


What can cause the engine temperature to be high in piston engines?

Low oil quantity, improper cooling, running excessively lean of peak.  Excessive boost from a turbo or supercharger at high altitudes where sufficient cooling is not possible.  Ther are quite a few reasons.


Are there any cockpit indications when an engine has separated from the aircraft?

This is the indicator that shows you when one engine falls off in a multi-engine aircraft:

If the right engine falls, off, the little ball will move left. If the left engine falls off, the little ball moves right.

If you only have one engine, or both engines fall off, you need to use a different indicator that looks like this:

if both engines fall off, this white pointer will start to move towards the "40", and you might hear an alarm, a voice shouting "stall, stall", or feel the stick shake.

if you have one engine and it falls off, the white pointer will move, but in an indeterminate direction.


Does the wake from horizontal stabilizers merge with the wing wake?

Yes, when viewed from far enough away.
Close up, both will have their own developing wake. The boundary layer leaving wing and tail will leave a speed discontinuity, and the downward moving wing wake will be complemented by a tail wake, which will slow down this downward movement directly behind the tail, and increase it left and right of the central tail wake. Normally, the horizontal tails of transport aircraft produce a considerable downforce during landing to compensate for the backward shift of the center of pressure when the high lift devices are employed.

Aircraft model flying through illuminated smokescreen (picture source)
This animated GIF shows the wake of the tail as a darker box inside the bigger wing wake. It forms two small vortices which rotate against the rotation direction of the wing wake and get spread out when being absorbed by the wing wake.
Friction will soon dissipate the much weaker tail wake, so at some distance all what is left is a single wake which looks slightly distorted around its center, when compared to the wake of the isolated wing.
Fun fact: The negative lift on the tail can even contribute thrust.


It doesn't really make sense to "go and get" a type rating for any large aircraft. A type rating on a 727 would be very expensive for most people, when the airline that needs pilots will likely train you when you're hired. If the bulk of people that have the rating are gone, and the airline needs pilots, it will either have to be very patient when searching for pilots, or it will train new pilots.


According to a story in Flying Magazine Nov 1956, the Grumman SA-16 Albatross in that story (see page 58) carried an anchor.

For pre-flight, the FAA says:

  Check that necessary marine and safety
  equipment, such as life vests, lines (ropes), anchors,
  and paddles are present, in good condition, and
  stowed correctly.

(FAA)

(wikimedia.org) Nose access on the Albatross.

The answer seems yes.


How are Rolls-Royce engines different to others?

Yes, RR engines typically have 3 spools while GE and P&W generally have 2.  There are several design tradeoffs.  Briefly:

3 spools are easier for the aerodynamic design. For example, compressor stall can happen when the front stages of the compressor are pumping more air than the back stages are able to accept.  On a 2 spool machine, the front and back stages are all on the same shaft going the same speed.  However, on a 3 spool machine, the front and back stages are on different shafts.  So one shaft can speed up or slow down to better match the stages.  To work around this issue, 2 spool machine usually need to have more variable geometry (such as variable stator vanes) than 3 spool machines.

2 spools are easier for the mechanical design.  Every spool needs to be supported by bearings.  More spools means more bearings.  Bearings have to be supported by frames and cases.  More bearings means more frames (or more complicated frames).  Every spool has critical speeds. So more rotors means more possible critical speed issues.

There is not a clear winner.  2 spools are better for some things but 3 spools are better for the other.  Each company is going to tell you that theirs is "the best", but really they are about even overall.


Would an area-ruled fuselage improve the MiG-15/17's performance?

In a word, yes. But that sort of depends on the definition of "performance". The top speed would likely be effected only in a minor fashion, but the transonic acceleration would likely improve, as would the fuel economy.

It is worth pointing out that, largely by luck, many of these aircraft got some of the benefits of the area rule without specifically designing it. The location of the cockpit behind the intake required the fuselage to become larger in that area, especially when one considers the canopy, which ends just in front of the wing. And then the tail begins near the end of the wing and the fuselage begins to narrow behind the engine as well.


Why do airplanes bank sharply to the right after air-to-air refueling?

Fighter jets are very maneuverable, so they may make anything from a shallow bank to a breakaway maneuver. The breakaway is a standard way for fighter jets to exit a formation. It provides a way to safely and quickly gain separation from the other aircraft.

In this case the bank is fairly shallow, but when the aircraft disconnects they are already in a shallow right turn, so the total bank angle is a bit larger.


What would be the ideal plane specs that minimizes consumption for 1000 kg of cargo payload (slow speed, wing span, whatever..)?

The most fuel-efficient configuration would be one having a very high L/D. The best examples are modern sailplanes, aerodynamically clean, and with very long, slender wings.


Is there information available about an aircraft incident from New York to LHR in 2004?

Here it is: British Airways flight diverted to Bangor.

  At about 8 p.m. British Airways Flight 112, traveling from John F. Kennedy International Airport in New York City to Heathrow Airport in London, diverted to Bangor after smoke was discovered in the cockpit.

Story was published on June 10th, 2004. Article says Wednesday night, so it should have happened on June 9th.

Both the AAIB and the NTSB don't have any reports. It must have been a minor issue. Just a BA 777 on the same day, fuel leak on departing Heathrow.


Are there any real life instances of aircraft aborting a takeoff or landing to avoid a vehicle?

Not only is it possible but it happens. This is formally called a "runway incursion" and it does happen like 2005 Logan Airport runway incursion or the B733 / vehicle, Amsterdam Netherlands, 2010. Skybrary has a full list you can find here which is quite lengthy and includes a full section for Vehicle Incursion.


What is the optimal time to get from ASEL to ASES certification?

The instrument airplane PTS has both maneuvers for single and multi engine airplanes. Obviously, when you first get your IR in an ASEL airplane you cannot complete the maneuvers required for multi-engine airplane.  Hence, if you choose not complete those maneuvers when you take your AMEL checkride, you will be limited to VFR.

There are no specific IR maneuvers in a seaplane so once you complete your IR in a ASEL airplane, you will also have IR privileges in a ASES airplane.

The answer is found in the instrument PTS / ACS book.

If you were to have both ASEL and AMEL ratings and took your initial IR in a AMEL, it would be valid for all aircraft that you are rated in or get rated in later on: ASEL, ASES, AMEL, AMES.


What is “Weather and Chaff” information provided to pilots by ATC?

In the Pilot/Controller Glossary, this is the definition of "Chaff" and would be its meaning in the context of "Additional Services" referenced in your question.

CHAFF- Thin, narrow metallic reflectors of various lengths and
frequency responses, used to reflect radar energy. These reflectors,
when dropped from aircraft and allowed to drift downward, result in
large targets on the radar display.

On some radar equipment chaff may appear similar to areas of precipitation.


What does the term "loading" refers to when we talk about Blade loading and Stage loading in Turbomachinery?

The term “blade loading” is basically the same as “pressure ratio”. A blade with a higher blade loading causes the exit pressure from that blade stage to be higher than if the blade loading was lower. Hence, the pressure ratio (exit pressure/inlet pressure) is higher when the blade loading is higher.

The optimum number of blades is a very complex problem. But, in simple terms, too many blades, and the weight is too much, too few blades, and either the exit pressure of the compressor is lower (which makes the engine less fuel efficient), or the pressure ratio across each blade is higher, and the engine is much more likely to suffer compressor stalls. The fuel control may have to allow only a very slow acceleration and deceleration rate, to avoid stalls. It may also stall more easily in crosswind situations. Neither of these are ideal in a take-off situation. You don’t want the engine coughing and losing thrust when you are past the point of aborting the take-off, but aren’t high enough to fly a circuit and land.


The strakes (or root extensions) only have a secondary purpose aerodynamically. Mainly, they solved a particularly vexing problem on the Rutan canard designs (Vari-eze and its offspring), where the wings were swept and the operating C of G  was forward of the wings due to the canard configuration; where to put the consumable load, the fuel, where it can be as close as possible to the C of G.
You couldn't put fuel in the main wings farther aft, because depletion of fuel moved the C of G forward too much, and the Vari-eze already suffered from C of G and main gear placement issues due to the pilot forward, forcing Rutan to use the kneeling camel nose gear arrangement to avoid a tail skid to hold the back end up when empty (a really big problem when there's no tail to speak of, just a propeller).
There was no room in the fuselage for a tank of significant size and still have space for any baggage.  That left the sides of the fuselage ahead of the wing leading edge. He could have just put blisters there for fuel tanks, but that makes drag with no other benefit. The root extensions were an obvious and much more elegant solution.  Minimal drag increase, and a beneficial aerodynamic effect at high AOA, and plenty of fuel volume that changes the balance very little when depleted.
The presence of the strakes moves the mean area of the wing forward somewhat, but minor adjustments to the configuration take care of that.
"Regular" airplanes can put fuel in the straight wings and don't need strakes of that size and if they are used, there are strictly to improve stall behaviour. Some homebuilt owners, like the Thorp T-18 guys, have experimented with small leading edge strakes to improve high AOA behaviour, but these were only about the size of your hand and are just being used as vortex generators (can't find a pic of one so far).


Are there aircraft with multiple inlets for a turbojet engine?

It’s common on military fighters. For instance most single engine fighters eg F-35, JAS-39, J-18, etc. will have a pair of inlets on either side of the fuselage feeding these single engine.  Some aircraft will have auxiliary air intakes eg B-2, F-117, F-22, MiG-29/35, SU-27/30/33, etc. to provide additional air on takeoff or other high power settings or to provide protection against FOD ingestion.


Is there a minimum altitude for ejection seats?

It depends on the ejection seat.

Modern zero-zero ejection seats are designed to be usable at zero speed, zero altitude.

Older ejection seats had different minimums which varied from model to model.

On a side note, the early F-104 ejection seats required quite a bit of altitude to deploy properly, since the pilot exited through the bottom of the aircraft. This was done because there was some concern that the pilot would hit the F-104's T-tail with a standard ejection seat.

EDIT

It appears that it may actually be possible to eject from an inverted aircraft. According to Wikipedia (bold added for emphasis):

  The minimal ejection altitude for ACES II seat in inverted flight is
  about 140 feet (43 m) above ground level at 150 KIAS. While the
  Russian counterpart - K-36DM has the minimal ejection altitude from
  inverted flight of 100 feet (30 m) AGL. When an aircraft is equipped
  with the Zvezda K-36DM ejection seat and the pilot is wearing the
  КО-15 protective gear, he is able to eject at airspeeds from 0 to
  1,400 kilometres per hour (870 mph) and altitudes of 0 to 25 km (16 mi
  or about 82,000 ft). The K-36DM ejection seat features drag chutes and
  a small shield that rises between the pilot's legs to deflect air
  around the pilot.


Why do military aircraft use a different kind of aviation fuel?

Military aircraft can and do fill up on civil Jet-A -- this is common at facilities where the extra expense of providing both Jet-A and JP-5 or JP-8 fuel isn't worthwhile.  However, the military jet fuel types do provide some advantages over Jet-A:

JP-5 has a high flash point, improving its handling properties over civilian jet fuels.  This is important for fire safety in the close confines of an aircraft carrier.
JP-8 is similar to civil jet fuel, but also has extra thermal stability additives in it.  This allows for longer-term storage under harsh field conditions, and better resistance to deposit formation in places like afterburners and fueldraulic movable nozzles where the fuel is exposed to high temperatures even before it's burned.  It also may be specified for properties such as cetane rating that are essential for proper performance of diesel reciprocating engines run from JP-8.

(I'm omitting JP-4 from this discussion as it's a wide-cut fuel, comparable to civil Jet-B, and was retired from USAF service in 1995.)


Are there any rules regarding construction near a private strip, such as stand off distance?

Best is to contact your FAA regional office as the details of the procedures seem to vary a bit depending on your region, and the use of the airport.

AC70/7460 gives guidance the lighting and lighting of obstructions that may affect the airspace. The first paragraph reads:

  A sponsor proposing any type of construction or alteration of a
  structure that may affect the National Airspace System (NAS) is
  required under the provisions of Title 14 Code of Federal Regulations
  (14 CFR part 77) to notify the FAA by completing the Notice of
  Proposed Construction or Alteration form (FAA Form 7460-1). The form
  should be sent to the Obstruction Evaluation service (OES). Copies of
  FAA Form 7460-1 may be obtained from OES, Airports District Office or
  FAA Website at http://oeaaa.faa.gov.

More information can be found here   here.

The reporting requirements are laid down in CFR 14 part 77 §77.9


What is this aircraft seen at Peachtree City, GA?

It's one of many privately owned Aero L-39s, some of which are in the US. Here's one registered in Georgia, USA, with a similar livery at the same airport:

(flickr.com) N915WE.

  N915WE Aero L39C
  Preparing for takeoff. Falcon Field-Peachtree City, Ga.

It could actually be the same one you photographed.


When was Kai Tak permanently closed to cargo service?

The cargo terminal was closed for good by 24th August, 1998.

First Anniversary of Hong Kong SAR: Infrastructure Development

  Air cargo handling was more seriously affected by problems with the automated handling system at the new 'Super Terminal 1' operated by Hong Kong Air Cargo Terminals Ltd (HACTL). This forced HACTL to re-open its air cargo facility at Kai Tak until the new terminal at Chek Lap Kok - one of the world's biggest - was running smoothly. By August 24, all incoming and outgoing air cargo was being handled at HACTL's new Super Terminal 1.


What is the difference between a service manual and a maintenance manual?

I don't see the definition in the FAA site.  But based upon experience in military aviation we look at them as synonymous terms. The terms differ at the frequency and level of care provided by maintenance technicians.
https://www.faa.gov/guidance/
Maintenance manuals are aligned with the term Operations & Maintenance manual, which is for daily operations maintenance and corrective actions.
Service manuals are for longer interval maintenance practices when the aircraft is in the hangar undergoing longer maintenance projects.
Ex:  engine flush vs engine disassembly


What's the correct ATC phraseology to enter a nonpublished hold?

You didn't mention any particular country or jurisdiction, but for the US the FAA's ATC orders say in section 4-6-4:

  PHRASEOLOGY−
   HOLD (direction) OF (fix/waypoint) ON (specified radial, course, bearing, track, airway, azimuth(s), or route.)

  If leg length is specified,
  (number of minutes/miles) MINUTE/MILE LEG.

  If
  direction of turn is specified,
  LEFT/RIGHT TURNS.


What would the density profile of this shock wave look like, roughly?

The shock observed is effectively the same as the one over a wing. Compression waves are normally considered of infinitesimally small thickness, although due to the non-continuous nature of gases made of particles, this normally makes the shock on the same order of magnitude as the mean free path of a gas molecule (See here for the values at different altitudes).

For visualization's sake, here's a CFD from a transonic NACA0012 airfoil with a shock on the suction side, and a plot of the density gradient on its surfaces. The step in density is not a pure discontinuity, as it would be physically, due to the relatively coarse mesh used, but I hope it still delivers the idea.


Is 'bouncing' an airliner on landing in high winds a deliberate technique, or something always unexpected?

Bouncing a landing is neither intentional nor desirable. There are several reasons why a student pilot might bounce, but for a professional pilot, it's most likely related to wind gusts, which are a challenge no matter how much training and experience you have.

Gusts are by their nature unpredictable, and if one hits the plane right as it's touching down, it can suddenly lurch upward and/or downward, resulting in a bounce. That's probably also why your plane was "rocking" before landing.


Are turbofans compensated for gyro effect?

There are a few counter rotating turbo fans, such as the GEnx. But the majority are co rotating.


Does lift coefficient vary with the wind velocity for a given angle of attack?

Yes, it does vary slightly due to viscous effects.

In inviscid flow, the flow speed would not affect the lift coefficient - angle of attack relation. However, increasing the flow speed will result in a thinner boundary layer and a slightly different shape of the airfoil - boundary layer combination as "seen" by the outer flow. This influence is captured by the Reynolds number. See below for a plot of the venerable NACA 4412 from Abbott and Doenhoffs collection of airfoil data (picture source):

Note that the lift coefficient is plotted for Reynolds numbers R of 3, 6 and 9 million.


How do I determine holding pattern entry and direction in this example?

Neither of the two representations show holding North if the arrow depicted in the corner is truly pointing towards 150°. If this is the case, North is at the bottom of the page and South is at the top. Therefore, both representations are showing holding South of the fix.
If the dot depicted is the fix, the representation on the left is not a holding pattern. Holding patterns have their inbound leg terminating at the fix. Your turn towards the outbound leg would then begin when crossing the fix on the outbound leg.
Furthermore, your HSI is showing that you are on the 150°  To-Radial of the fix, on a 155° Heading, and a 16.5 DME. This would put your aircraft inbound, 16.5 Nautical Miles North of the fix, roughly on the 330° From-Radial (or just Radial). You should intercept the inbound leg 360° Radial of the fix well before crossing it. Then effect a Direct Entry, Performing your 5Ts Once you hit the fix with wings level.
You could, however, continue direct to the fix, inbound on the 330° Radial, and still perform a Direct Entry. I just, personally, think it’s easier to intercept the inbound (360° Radial) leg first.
Research AIM 5-3-8 for further details.


What are the different structural weight limitations that have to be considered when loading large aircraft?

Is there a difference in complexity as to whether it's a passenger aircraft or a freighter being loaded?

Yes, very much so. The resulting load of a passenger in every seat is nowhere near close to the structural limits (note that I said structural limits, not performance limits). Generally speaking, having to check for the load being within structural limits is a concern for freighters, not passenger aircraft.

There are a lot of structural considerations for the semi-monocoque design used for all modern large aircraft. Using one variant of a 747-400F as an example, its Weight and Balance Control and Loading Manual runs to 584 pages. Items that need to be checked for each load include:

Linear and Floor Loading

The manual snippet above covers the main deck; there are like tables for each cargo area. The linear loading is the lb/in measured along the longitudinal axis of the airplane. I don't really understand why it's necessary to check both the linear loading and the floor loading, given above as lb/sq ft.

Not only does the linear loading for each cargo compartment need to be checked, but the combined linear loading of all decks together along the longitudinal axis has separate linear limits as tabled below:

Cumulative Loading

There are cumulative load limits for both the forward body and the aft body. Using the forward body for example, you add up individual items (more often than not ULDs) starting at the front and proceeding to a point over the wing box. I'm not sure exactly how that point is chosen insofar as structural and aerodynamic considerations are concerned. The aft body cumulative load starts from the tail and proceeds to the same point.

Below is a forward body cumulative limits graph. Note that there are two lines: one for use when the ZFW is 610,000 lbs or below, one from that weight up to 635,000 lbs. For this particular airplane, the aft body also has two lines, but the differentiation is based on the takeoff c.g.. Some 747s have only one line for each, some one line for one but two lines for the other. Obviously things can get tediously complex, and loadmasters and the software they're using has to accommodate all the possibilities.

Unsymmetrical Main Deck Limits

Widebody aircraft that can accommodate two rows of ULDs on the main deck have the option of carrying more weight in one container if the container laterally next it is given a lower limit. I know of one operator that didn't want to contend with the limit of, say, the position on the left being higher than the position on the right, and chose to forego the flexibility of unsymmetrical limits. An unsymmetrical limit graphs is below:

So, does anyone want to do a weight and balance for a large cargo aircraft? Fortunately we have software to do that for the great majority of loads that are containerized. However, loadmasters might still have to contend with unusual loads manually.


How long does the gear extension/retraction takes on the ATR-42?

In this youtube video showing landing gear maintenance operations on an ATR42, I'd say about 11 seconds for both extension and retraction.
A more precise timing could be gathered from an uninterrupted cockpit video, measuring from gear lever action action to "three green" on.


How to convert a pressure height (ADS-B) to a geometric height?

ADS-B gives both pressure altitude and geometric altitude.

In the position messages you will find the pressure  altitude which is essentially a pressure converted to an altitude. For this conversion the ICAO Standard Atmosphere is used.

In the velocity message you will find the difference between the geometric altitude and the pressure altitude. Since the difference between them is fairly limited a few bits could be saved by encoding the difference instead of the geometric altitude.

If you don't have the geometric altitude and you want to obtain it from pressure altitude (regardless where it cones from) you will have to know the relation between pressure and geometric altitude in the atmosphere.

You can model it according to the hydrostatic equations of the ICAO Standard Atmosphere and correct for actual temperature, lapse rate and local pressure. This gives fairly good results.

For higher altitudes data from meteorological models can be of help to improve accuracy.


What cargo airplanes can transport fully assembled large turbofan engines?

Engine nacelles are part of the aircraft and not the engine. I think you're asking about fully assembled engines.

Oversized jet engines are usually transported by road when possible; in case air transport is required, the Antonov An-124 'Ruslan' is your best bet. It is the only aircraft capable of transporting engines like the Engine Alliance GP7000 and RR Trent XWB.

Image from antonov.com

For smaller engines (or partially disassembled ones), other aircraft like the Boeing 747F and A330-200F are used.

Interestingly, this filing with US DoT shows the An-124 being used to transport GE GEnx engines from Rickenbacker airport to Seattle to ensure smooth production in Boeing factories.


How far from a taxiway, can a walking or biking trail be built?

ICAO recommends somewhere between 16.25 and 57.50 metres from the centreline, depending on the type of aircraft that use the taxiway (code letter A-F).
From ICAO Annex 14:

3.9.8    Recommendation.— The separation distance between the centre line of a taxiway and the centre line of a runway, the centre line of a parallel taxiway or an object should not be less than the appropriate dimension specified in Table 3-1, except that it may be permissible to operate with lower separation distances at an existing aerodrome if an aeronautical study indicates that such lower separation distances would not adversely affect the safety or significantly affect the regularity of operations of aeroplanes.

...

3.11.1    A taxiway, other than an aircraft stand taxilane, shall be included in a strip.
3.11.2    Recommendation.— A taxiway strip should extend symmetrically on each side of the centre line of the taxiway throughout the length of the taxiway to at least the distance from the centre line given in Table 3-1, column 11.


What is the correct phraseology for declaring a fuel emergency?

(This is very closely related to this question, and see this one too.)

At least in the US, cutting into fuel reserves isn't an emergency by itself. But assuming that things have gone beyond "minimum fuel" and you clearly need priority for landing then you should indeed declare an emergency.

The wording you mentioned seems 'weak' to me; if you do have to declare an emergency, there should be no possible doubt about it or about what you need. Assuming that I was already in contact with ATC, I'd probably say something like this (see the AIM 6-3-2):

  Mayday, mayday, mayday. Louisville Approach, N12345 is declaring an emergency, low fuel. We are now direct runway 35R for landing. 3 on board, 15 minutes fuel remaining.

Note that if time is critical I'm not going to "request" anything, I'll just tell ATC what I'm doing and let them sort out the rest. That phraseology and statement of intentions should be understood anywhere in the world.


What medical issues or procedures can cause denied medicals?

Its really no big secret, the FAA publishes their full guide for AME's and you can read it if you like (all 514 pages...) and generally speaking it lists a lot of the disqualifying factors. They offer various guides as well, all of which are public.
If you are worried that something relating to you personally is grounds for denial you can always reach out to an organization like AOPA for assistance.
Routine Procedure is a fairly broad term and an answer cant really be provided since this can be highly case by case depending on what the procedure is.


Some answers:

  1) How much does it cost.

Cost will vary based on numerous factors, such as your age; being older seems to take more hours than younger - different reflexes, different reactions compared to experience from other motor vehicles. At the same time, being older one can probably be able to fly more regularly, which really helps. Or perhaps not if being older one is stuck with house and car payments and saving for college, etc.
For a full-up private license, a minimum of 20 hours of dual and 20 hours of solo time is needed.  I started at 33, could afford twice a week, missing a lesson seemed like two steps back at times. Ended up with about 70 hours total by the checkride, and my wife ended up with similar when she got her license a couple of years later.

  2) Get a cheap plane or chopper

I believe Plane will be less cost - helicopter lessons are more. Must be a maintenance thing - they do seem to just want to vibrate themselves apart! The times I have looked into it, helicopters seemed to be twice as much.

  3) Where to take lessons

Someone else already answered - find an airport near you and ask around.  If it becomes too impractical for you to get there on a regular basis, you may not be likely to keep doing it.

  4)Theory and practical

Depending on the school, you may or may not be required to take "ground school" with them, where a lot of basics are covered, and prep for the knowledge exam and the checkride is done.  Being a college grad, I took the self study path instead, and anything I couldn't figure out, or didn't understand, I brought up during flying lessons.  Jeppesen.com has good study materials, as well as courses you can find at Sportys, King Schools, etc. Once you apply for the student license/medical, you will get a lot of stuff in the mail.  Do that early to make sure you can pass the medical (it's very basic).  Ask at the airport for recommendations on nearby Aviation Medical Examiners (AME).

  5) Is there a difference which plane or helicopter I may fly, especially in size

Airplanes, you may start in a small 2-seater (I started in a Cessna 150) or a somewhat larger 4-seater (Cessna 172 is very popular), or a similar low wing plane from Piper (like a Cherokee).  Helicopter, the Robinson R-22 is a popular 2-seater for starting. R-44 for 4-seats.

Which license you go for depends on your "mission".  Want to take some friends up and go sightseeing without spending a fortune? Plane I suspect is more affordable.  You can also look at "trade a plane" magazine to see prices on what's for sale in the used market. There are also plenty of kit planes and helicopters and gyrocopters you can build if so inclined.

There are also plenty of very light sport aircraft (LSA) planes, basic 1 and 2 seaters with limited speed and fuel capacity, not intended for more than just local flying, but longer trips would be possible with some tenacity.


Do adding high thrust in plane prevents it from stalling?

Every aircraft can be made to stall with a combination of low speed, rear c.g. location and high load factor.

Thrust acts in the airplane's lengthwise direction. Lift acts in a mostly perpendicular direction, so whether the aircraft stalls does not depend on its thrust when lift demand exceeds the available lift capacity.

As you observe, this will not be the case in a climb. We know that lift demand is actually lower in a climb than in steady flight. So we need to look somewhere else.

The obvious case is in turning flight when the aircraft has to counteract not only gravity but also a centrifugal force. Now lift demand can grow to multiples of that in steady flight and any aircraft will readily stall if mass times normal acceleration surpasses the lift capacity of its wings. More installed thrust will only reduce the rate of energy loss in a tight circle.

Only if pitch authority is not sufficient can stall be avoided, but then the control system will not allow to trim the full angle of attack range. This could conceivably happen with a very forward center of gravity location but should place this configuration outside of certifiable limits.

As a side note: Stall depends on more than just the angle of attack.


What effects to controllability are there when the rear doors are opened on a KC-130?

Answer based on information found on-line. Related documentation:

USAF C-130 Operations Procedures
C-130T Flight Manual
Lockheed News Service, 1957
KC-130 Specifications
KC-130J Specifications
C-130 HALO Practices

C-130J Hercules
Source: Flight Global

The KC-130 Hercules is the tanker variant of the C-130 Hercules. The cargo opening consists of a door, and a ramp which can be operated separately.

The door is opened by rotating up and inwards the top panel.
The ramp is opened by rotating down and outwards the lower panel

Source: CQ Planes Spotting

KC-130 / C-130 have a good maneuverability at low speed.

From the the C-130 flight manual:

Door and loading ramp are operated at a speed of 150 KIAS, with flaps down at 50%.
Same conditions for flying with door and/or loading ramp open.

Low speed adjustments:

Reducing speed from 300 kt to 150 kt requires nose up trimming.
The center of gravity may be adjusted by ballasting fuel in the tanks (refueling tank and aircraft tanks).

Opening the ramp will change the aerodynamic shape of the aircraft:

The ramp will not be moved past the horizontal position (only need for full down position is to load cargo on the ground).
Moves the nose down.
Balanced by some trim accordingly.

If loads are dropped (pallets, paratroopers) or fuel is delivered, the center of gravity will roll back, with a significant nose-down tendency, and trimming will be required.

Opening the door will be less of an issue as seen on the image below:

The aircraft is near level.

Above: KC-130J Hercules (source: Military.com).
Note that the attitude is not so far from level, in spite the door is open.


How miraculous was the miracle on the Hudson?

This would be an extremely difficult question to answer without being opinionated, but I'll give a try. As part of the investigation, the NTSB, along with other agencies carried out a number of tests on simulator, where pilots were tasked with either landing or ditching the aircraft.
There were three different scenarios contemplated:

Normal landings on runway 4 at LGA, starting from an altitude of 1,000 or 1,500 feet on approach;

Attempted landings at LGA or TEB after the bird strike, starting both from zero groundspeed on takeoff from runway 4 at LGA and from a preprogrammed point shortly before the bird strike and loss of engine thrust, and;

Ditching on the Hudson River starting from 1,500 feet above the river at an airspeed of 200 kts.

In the first case, all the landings were successful, which is not surprising. However, in the second case, landing was successful in (slightly) more than half the cases, but only where the response from the pilot was immediate (i.e. there was no delay between loss of thrust and decision to return to airport).

Regarding the second flight scenario, 20 runs were performed in the engineering simulator... Five of the 20 runs were discarded because of poor data or simulator malfunctions. ... In eight of the 15 runs (53 percent), the pilot successfully landed after making an immediate turn to an airport after the loss of engine thrust.

In the one case where a (35 sec) delay was included, the landing was not successful.

One run was made to return to an airport (runway 13 at LGA) after a 35-second delay, and the landing was not successful.

It has to be noted that in all these cases, the pilots were already briefed about the manoeuvre they were about to perform.
The third series of tests were conducted to see whether the pilots were able to achieve the target flight path angle of -0.5$^{\circ}$. Only one Airbus test pilot was able to come near that value. From the report:

Regarding the third flight scenario, a total of 14 runs were performed in the engineering simulator in which pilots attempted to touch down on the water within a target flightpath angle of -0.5°, consistent with the structural ditching certification criteria. Two of the 14 runs were discarded because of poor data.
In 11 of the 12 runs, the touchdown flightpath angle ranged between -1.5° and -3.6° (the touchdown flightpath angle achieved on the accident flight was -3.4°). In 1 of these 12 runs, a -0.2° touchdown flightpath angle was achieved by an Airbus test pilot ...

From these simulations, it appears that the flight crew took the correct decision to ditch in the river. Also, we have to take into account that taking decisions in real world under extreme stress is quite different from taking them in a simulator. The report notes that,

The one simulator flight that took into account real-world considerations (a return to LGA runway 13 was attempted after a 35-second delay) was not successful. Therefore, the NTSB concludes that the captain’s decision to ditch on the Hudson River rather than attempting to land at an airport provided the highest probability that the accident would be survivable.

Another thing to note is that there was no simulator training to the pilots, either as part of the airline or manufacturer program. In fact, the dual engine failure scenarios were presented only at high altitudes.

Ditching scenarios were not included in either the US Airways or Airbus simulator training curriculum.

A similar incident happened in case of the Scandinavian Airlines Flight 751, where the pilots successfully landed the aircraft without any fatalities.
One also has to consider the other issues in ditching in water (like the associated visual illusions). From these, we can form the opinion that a sizeable minority of airline crews would have ditched the aircraft successfully on the river after bird strike so as to enable rescue. As for zero fatalities, it would be near impossible to say that with any certainty, as there are too many factors in play here.


Why does Schiphol airport have such a long taxi way?

Firstly, I'd like to make clear that the particular reasons for the placement of the taxiway are not all publicly disclosed, and there are undoubtably multiple factors involved. After looking at the airport in Google Maps, I notice a couple things. (Excuse the large picture, explanation below!)

1) Physical & Geographical Limitations

There is a pre-existing highway in between the runway and the rest of the airport. The runway could not be placed closer to the airport in the current direction without either removing the highway, or bridging over the highway (as the taxiway does). The highway would be unlikely to ever be removed, due to the extreme cost of removing pre-existing infrastructure, nor would they like to bridge a runway over the highway. Runways require a fair amount of maintenance in comparison to taxiways, and including a bridge in the design of said runway would drastically increase the cost and complexity of maintenance.

Looking at the map, there is absolutely nowhere to place a runway of that length and bearing without drastically engineering a solution. Beyond that, there does not seem to be anywhere within the "block" of the main airport to create a runway of that size, regardless of bearing.

2) Noise Abatement

The fact that the runway is in a less dense area also means that aircraft on approach would cause less noise disturbance for the populated areas nearer the core of the airport. In fact, for the northern approach, there are not many developed areas - it is primarily open fields. Aircraft are only allowed to takeoff to the north, and land from the north, on this runway, to avoid overflying the populated areas to the south of it.

3) Other Potential Factors

The above reasoning we can be relatively certain about. However, there may be other contributing factors, such as ground quality. As there are rivers and streams nearby (including the one that the taxiway bridges), much of the ground may be more difficult to build on, and require more expansive foundations.

Conclusion

Regarding a taxi time of twenty minutes, there is certainly potential for a taxi of that length, but it is not due to distance. The distance is not anything extraordinary compared to many other "Hub" airports. The time is likely substantially increased by the fact that, if runway 18/36 is in use, they will likely be told to taxi around 18/36. The primary reasons for the creation of this runway, cited by the planning committee, were arrival/departure capacity and noise abatement.

While this is certainly not a very efficient system, it is certainly the only solution I can see to provide a runway of that size. There could be various improvements, but cost is the overarching factor.


Does the EASA/FAA require additional life vests, and life vests for infants/children?

From the FAA's Flotation Equipment for In-Lap Children InFO (Information for Operators):

The FAA recommends:

  Consider installing flotation equipment designed specifically for in-lap children.

(Emphasis mine.)

We also find:

  If an air carrier provides flotation equipment for in-lap children that is located or operates
  differently from the typical flotation equipment for other occupants, then additional information
  regarding that special equipment would be required in the briefing given to passengers.

Which means it will briefed to the passengers if it is present. (Too many if's.)

For the FAA, there is no requirement to have multi-sized flotation devices. Remember, seat cushions work well, and infants aren't good swimmers, but they also don't panic in water (maybe not all of them).

  A reflex called the bradycardic response makes babies [up to 6 months] hold their breath and open their eyes when submerged in water, says Jeffrey Wagener, a pediatric pulmonologist in Colorado. (Source)

Cute video: Baby's first swim - underwater!


Why do most authors use wingtips vortices as reason for 3D flow around wing?

It depends a bit on the definition of a "wing tip vortex".
If this is defined as just the local flow around the wing tip, it is too narrow to encompass all 3D effects and you are right.
If, however, the term "wing tip vortex" describes the beginning of the whole wake rollup process caused by downwash and sideways flow, then this does cause induced drag. The vorticity behind the wing cannot create drag anymore; this can only be done by things happening directly at the wing. But induced drag is spread over the whole wing and not restricted to its tips, so the "wing tip" part of the name is misleading.
In my view of the process, induced drag is caused by the gradual bending of the flow by the wing. By bending an already deflected flow further downwards, the reaction force must have a backwards component, which is induced drag. Note: No wing tip flow required for the explanation! But that is too simple, or pure 2D drag would also produce induced drag. In fact, the flow is first bent upwards ahead of the wing (induced angle of attack) so the bending happens not beginning with straight but upwards moving flow. Without the added downwash of the trailing vortices, all effects cancel out so only a vertical force is left. Add the downwash over the wing produced by the free vortices and - bingo! - the backward component is precisely the induced drag added in 3D flow.
The often-heard explanation that the flow around the wingtips causes induced drag is much less helpful and similar to saying that wet streets cause rain. In the end, wingtip flow is only a reaction to local pressure differences, in the same way that the induced angle of attack is. And it is this pressure difference over the whole span which causes the flow to bend around the wing and be accelerated downwards. This downward movement then causes wake rollup and the wake vortices, which in turn start at the wingtip.
As to the "why" you are asking: In my opinion it is copying from others without fully understanding cause and effect.


Have any large aeroplanes been landed — safely and without damage — in locations that they could not be flown away from?

TACA Flight 110 made a deadstick landing on a grass levee. Engines got replaced and it took off using a nearby NASA facility.

https://en.wikipedia.org/wiki/TACA_Flight_110


What should I look for when choosing a kneeboard?

You don't want something so big that it interferes with fully moving your control yoke/stick.  I have one that is about 1/2 sheet of paper in size (or about the size of an approach chart), that works good for me. Decent width of velcro strap to go around your leg.
Sportys.com has Aluminim VFR and IFR kneeboards, with good info printed right on it.  If you roll your own, they also have the same info available as a placard you could stick on.  The kneeboard and a few pieces of paper are all I've used.
I fly my own plane, so I can leave pens/pencils in places that are convenient for me.  If you are switching between planes, then maybe a kneeboard with holders for a pen or two would be handy also.
I also have a yoke mount clip that holds an approach chart. I found that trying to read a chart on my leg under the yoke was too difficult.  I may change to an ipad holder on the yoke as that seems to be the trend now.


Why is a part from a Boeing 777 being analysed by Airbus?

Why are they taking the wing to Toulouse, FR?

Because the part was found on the island of Réunion, which is French territory.

  Why is a part from a B777 being analysed by Airbus?

It is not. Airbus is not the only company/institution to have plants/facilities in Toulouse: The BEA (France's equivalent to the NTSB) also has facilities there.


Why is this 777 zig zagging over the Pacific (and delayed by 2.5 hours in air)?

It's just a glitch. The most reliable public live flight tracking site is Flightradar24.com (but even it has bugs), and it shows that CX806 has flown in more or less a straight line and will be arriving early.


Could the SR-71 Blackbird be used for nearspace tourism?

Significant issues with the concept: the SR-71 lacks RCS, so you'd lose attitude control if you got significantly above normal operating height.  I originally wrote that it doesn't handle in-flight restarts well, but apparently it has the opposite problem -- it needs them all too frequently in normal operation.  It's also not an aircraft built for near-vertical climbs or high-G maneuvers, so a zoom climb is outside its normal operational envelope.
So, you can't demonstrate long (> 1 minute) periods of microgravity without the likelihood of loss of aircraft, crew, and paying passenger.  Beyond that, however, there's virtually zero visibility from the rear seat.  Who'd pay $100,000 for a "near space experience" with no zero G and no view of the black sky and curved horizon?
Never mind the fact that the SR-71 doesn't run on standard jet fuel (JP-1 or Jet-A); the engines could be retuned to do so, but then wouldn't continue to operate at 80,000 feet ASL or push the aircraft to around Mach 3 at that height -- in other words, it wouldn't do what an SR-71 is famous for doing.  And the special fuel the SR-71 requires hasn't been manufactured since the aircraft were retired -- it would probably cost more to restart production of that fuel than you'd make back in a reasonable twenty-year "space tourism" operating life (never mind cost of refurbishing an aircraft, pulling still-classified equipment out of at least the passenger seat, training new pilots -- oh, right, you'd have to refurb one of the trainers, that would at least solve the passenger visibility issue)...
Bottom line: no chance.  You'll get a better experience with the Russians; at least they can do a zoom climb and have RCS to point the nose back down so they don't wind up in a flat spin like the one Yeager had back in the day.


Where is the weather data for the Garmin G1000 retrieved from?

That is coming from a satellite based XM weather service which provides a variety of weather products on demand to pilots using a G1000 system.


How far can A&P mechanics operate aircraft under US regulations?

The laws for an A&P are the same as they are for a pilot. To fly the aircraft you must cary the appropriate licenses and ratings required for the airframe. No special cases are made for mechanics even for return to service flights.

However mechanics often fire up the engines and may run them up outside of the hangar to test things. As far as I know no certified pilot is required to start up and run aircraft engines.

The part about taxiing is partially addressed here. I know that mechanics can get some kind of approval to taxi aircraft if they do not hold any licenses, when I flew out of KPNE I knew some of the mechanics on the field and they needed to get some training on radio operations (as it was a towered field) before being allowed to taxi aircraft.

The last limiting factor, that may be a bit more ambiguous is the insurance regulations. For example say you were to own a little C172, your insurance may stipulate that only you (and perhaps an instructor) was allowed to fly the aircraft. In this case it would be unwise for your mechanic even if properly rated to fly the airplane as your insurance policy does not cover that.


Does a headwind/tailwind affect your rate of climb?

A steady (continuous) head wind (or tail wind) will not affect your climb rate, only your climb angle. It means you will reach a specific altitude in the same time interval, but your ground distance will be affected.

A head wind increase (as in a gust) will momentary increase your indicated airspeed, which you can trade for a (momentary) increase of climb rate. Similarly, a tail wind gust will temporarily decrease your indicated airspeed and you might have to pitch the nose down a little, to maintain airspeed and therefore reducing climb rate. These are only transitory effects, until the plane settles back to its original trim speed.


What is the transient bleed valve in a gas turbine engine?

The high pressure compressor in a typical engine has many stages (e.g. GE90-115 has 9) all running on the same shaft, and thus all at the same speed. The problem is that sometimes the flow/pressure that the front stages are producing does not match the flow/pressure that the back stages are able to accept. When this happens, the compressor will stall (this is bad).

This can happen in several different situations, and one of them is a quick transient.  For example a very quick acceleration from idle to full power.

During this quick transient, the front stages might be trying to pump too much air versus what the back stages are able to accept. Eventually, everything will even out, but for a few seconds there may be a mismatch.

There are several different ways that engine designers can accommodate this situation.  One is a transient bleed valve.

When the engine performs a very quick acceleration, the transient bleed valve is opened and some of the air from the compressor is just dumped overboard.  When the engine reaches a steady operating condition, the valve is closed.


Why are the Constellation's nosewheels canted inwards?

@JohnK gives an excellent explanation for castor - the horizontal offset between the steering axis and the tire contact point.
But maybe the question is about camber. That is the angle between the vertical axis of the tire and the vertical direction relative to the ground. The camber angle on the Connie's nose wheels is called positive camber, and an extreme case can be found on the tractors of that time. Curiously, it is a distinct characteristic only of US tractors like the John Deere (left) and Farmall (right) tractors below (picture source).

The reason is easier steering in rough terrain. As a tractor discussion board explains:

I have read that positive camber is intended to align the kingpin axis with the center of the tire contact patch. Supposedly this reduces the force required to steer the axle. If that theory is true, then changing the height of the tires would change the intersection point of the camber angle and the kingpin angle; it's improbable that swapping between, say, the correct R4 tires and the correct R1 tires for your tractor would make significant differences.
However, I am not convinced by the theory that the positive camber is there for steering ease. Here is why: I think it would be easier to roll a tire around in a circle than it would be to simply twist it, especially if one considers the tire will be pushing dirt out of the way as it twists.
I think the reason for the positive camber is to attenuate the camber thrust that can occur when the tires encounter uneven terrain. This would tend to help the tractor track straighter, and require less steering input to maintain a straight course. That characteristic, along with the caster geometry, should make the tractor track straight naturally, rather than tending to turn more when either a steering input is made or some uneven terrain is encountered.

The author of this post has his own theory; however, the point made in his first sentence actually has merit: Since steering in automobiles and European tractors is made easier when the steering axis runs through the contact point of the tire with the ground, positive camber is an attempt to reduce the steering roll radius of the twin tires which indeed should make steering easier.

Steering axis inclination reduces the roll radius in cars (picture source); since the sideways axis inclination could not be used in nose gears or tractors, both resorted to tire camber.


How do "fundamentally unstable" aircraft deal with the risk of computer failure?

"fundamentally unstable" but über-responsive aircraft have multiple computers that take a vote on everything the pilot wants to do. If one computer fails the others will take over. There is often no direct connection between the control column and the flight surfaces so the "no computer aid" situation would be the same as #2.

If everything fails, the checklist is rather short: eject immediately.


What is this strut in biplane rigging, attached only to wires, not bearing any load?

It's just a stick set between the flying and landing wires (the "wires" are actually solid stainless steel rods with an almond cross section for streamlining - they are VERY expensive).  Normally they are made from wooden dowel with notches for the wires to fit, retained in the notches by wraps of lockwire, or on fancier biplanes they may be made from aluminum tube with a bullet nose and pointed tail.
They are usually called "wire stays". Their main function is to stop the wires from vibrating in the airflow (they're more or less metal vocal cords), which can create a lot of noise (that's the traditional diving airplane sound effect from the movies, as you can hear hear here, at 1:50:30, in Hell's Angels, one of the earliest sound movies with airplanes). The noise is from the "Wind in the Wires" (the title of a book by WWI pilot Duncan Grinnell-Milne). More importantly, the vibration can also induce fatigue cracking of the streamlined rods over the long term. Linking them together changes the natural frequency of the wires to something much higher than an individual wire, and stops them from vibrating in the airplane's speed range.


What's the relation between TAS and Mach in tropopause?

The speed of sound depends only on air temperature, not density. So, for a given temperature, a given Mach number will always equate to the same TAS.

In other words, for a given Mach number, TAS remains constant throughout the constant-temperature region above the Tropopause (ie. 37000ft to 65000ft in the International Standard Atmosphere, ISA).


Is failure to comply with evacuation procedures illegal?

No. The intent of the statute involves "assaulting or intimidating" a crew member. Passively failing to obey a crew member has no criminal liability nor does disobeying generic safety guidance given by crew members or aircraft literature.

The actual statute reads like this (49 U.S.C. § 46504):

  An individual on an aircraft in the special aircraft jurisdiction of
  the United States who, by assaulting or intimidating a flight crew
  member or flight attendant of the aircraft, interferes with the
  performance of the duties of the member or attendant or lessens the
  ability of the member or attendant to perform those duties, or
  attempts or conspires to do such an act, shall be fined under title
  18, imprisoned for not more than 20 years, or both.

Normally, disobeying a crew member generally has the effect of getting the passenger kicked off the flight. Note that a captain can remove any person for ANY reason from a flight, nor does the captain need to give a reason. Of course, if the flight is in progress, then removal is not an option.

(Also, note that this answer is for the United States only. In authoritarian/Salic law type places like France or Germany, they have laws that generally make it criminal to disobey authorities, which is different than the United States.)


How should I answer this question about measuring airspeed using dynamic pressure?

You're confused! Great! Confusion is just an opportunity to learn.

In the spirit of education, I won't answer your question, but I will give you some things to consider.

"Give your argument on the statement" - This usually means you're being asked to support or refute whatever comes next. It will be up to you to decide which is appropriate.
Measuring dynamic pressure - What is dynamic pressure? Are there other kinds of pressure? Is there something else besides pressure that could be measured instead?
is - Is it or is it not?
the way to - the only way? Are there other ways?
determine the indicated airspeed - Is that what is determined? Is anything else determined? Is indicated airspeed the proper thing to determine or do you need something else?
of an aircraft. - Is that correct?

If you can answer all of those, you should have no problem putting them together into a solution. If you're having problems with a specific portion, let us know what's unclear.


Where to find information on weight breakdown for helicopters?

Helicopter Performance, Stability and Control by Ray Prouty has a section on weight estimates on page 663. A few of the equations, rest are in the book:

I'm afraid Mr. Prouty used imperial units.


Do professional pilots have to show their passports every single time when flying back & forth between the same airports?

Pilots (and aircrew) usually go through an expedited security screening, usually separate from passengers, in order to reduce wait times.

For example, US TSA has a program called the Known Crewmember Program that allows pilots and crew members to bypass normal (passenger) security line.

Pilots (and aircrew) have to show the documents as required by the local authorities. Usually, this will be the passport/visa or General Deceleration. This varies from country to country.