Do logged hours with a Sport Pilot instructor count towards a private pilot certificate?

No.  Sport pilot instructors are not authorized instructors with respect to private pilot certification.

See 61.109(a).

The FAA has issued a legal interpretation on the matter.  See the Kern Ink interpretation


Why does my Cherokee PA28-180 Lycoming motor run hot?

You say it runs hot.  Why do you say that?  Is the oil temp pushing redline?  Do you have a CHT gauge?

EGT alone means nothing. Don't use it to set cruise settings.  What if the probes aren't all set 5" (or whatever) from the exhaust valve? What if they're only 3"?  Or 7"?  Or staggered between 3" and 7"?  Point is, the EGT number is just a repeatable value.  Don't think of it as a temperature.  Your Archer with probes 5" from the exhaust valve may read 1350° at full rich takeoff from sea level.  Your hangar mate with an identical plane (except for having probes only 3" from the valves) might see 1420° at the exact same setting.  Once you understand that EGTs aren't really temperatures and are merely reference numbers (or some type of "heat unit that isn't 'temperature'") the whole thing makes more sense.
Also, if you just have a single point EGT then just pretend it's not there and simply use the POH.  Single point EGTs tend to do more harm than good, especially if they're reading the confluence of two cylinder exhausts.  What possible useful information can you glean from an averaged temperature from half the cylinders on your engine, especially if it's carbureted?!?!

Does your mechanic know (and can he explain) why his tips make sense?  I'd love to hear his reasoning because I don't think it'll make sense.

You either have a bad oil pressure gauge or your pressure it too low.  Fix that.  A good gauge running below red line is very bad.  A bad gauge is better, but still bad.  The limits are not arbitrary.

Engine RPM limits are important.  Does Lyc publish a limitation between those RPMs for your specific engine suffix and serial number range?  If the limitation is an AD, has it been complied with and the limitation removed?
Running your engine at redline will not hurt anything provided the engine does not have a limitation (in the limitation section of the POH) on max RPM.  I know it feels right to "baby" the engine but there is no practical effect unless a limitation exists.  Note that "recommended procedures" are not "limitations."

I'd seriously consider talking with another mechanic if that's at all practical.  Your mechanic may be an airframe god but his advice regarding engines would have me shopping for a new IA.


Why is engine No.2 started first, instead of No.1?

The isolation valve in Open or Auto ensures that the Auxiliary Power Unit (APU) bleed air reaches the engine number 2 starter. Engine number 2 start Exhaust Gas Temperatures (EGT) are generally higher.

http://www.lt-vacc.org/images/mesti/Boeing%20737-300-400-500%20Operations%20Manual.pdf

Engine number 2 is started first because it's on the opposite side of the air bridge. When starting with external air or power it is normal to start Engine number 1 because it is further away from the carts.

http://theflyingengineer.com/projects/airbus-tech/hydraulic-systems/

According to Flight Crew Operations Manual (FCOM) 3 Standard Operating Procedures (SOP):

  Engine 2 is normally started first. It powers the yellow hydraulic system, which pressurizes the parking brake

Looking at the electrical schematic that Boeing provides, we see that Transformer-Rectifier (TR) 3 is powered from the R/H AC Bus. TR 3 is an important TR from which significant avionics are powered. Ergo, you would want to have this TR powered up and running first in case you lose AC power to the aircraft during start.


What is this pipe on the tail of this helicopter?

This device is the antenna for the HF transceiver.

Source

The antenna is the rigid wire running along the top of the fuselage and ending near the window, supported by insulators at regular intervals to move it away from the metallic fuselage for better efficiency.

HF antennas used on helicopters are often loop ("towel bar") and inverted-L antenna (the one you have found).

Length: RF signals travel in a wire and bounce at its extremities. This is also valid when this wire is used as an antenna. In that case the wire takes the name of radiator. The antenna radiates a stronger electromagnetic field when the direct signal and the bounced signal combine in an additive way in the radiator (resonance). This efficiency gain is also valid when working in reception.

RF signals travel in a wire at about 66 to 95% of the speed of light (velocity factor). To make the resonance happen the length of the radiator must be a multiple of the wavelength, or a carefully selected fraction of it, e.g. $\small 1/4$, $\small 1/2$, $\small 5/8$, ... (more) corrected by the velocity factor. The radiator size is therefore proportional to the wavelength used, and the radiator used in HF is longer than the radiator used in VHF.

Diameter: HF band also usually requires higher power (and higher voltage) for the long distance communications it is aimed to.

The result of both requirements is an HF antenna radiator should be longer and should have a larger diameter than for a higher frequency. This leads to designs similar to CH-53 antenna.

In practical the antenna won't resonate for all aviation HF frequencies which are spread over a large range (100 m to 10 m), shorter wavelengths will be privileged.

Some examples:

Source. Notice the smaller VOR/LOC antenna

Source

Source

See also: Why did some Caravelles have a very long dorsal fin?


What does the "remote control" for a QF-4 look like?

Here's a photo:

Retired Lt. Col. Thomas Mudge, a ground controller for the 82nd Aerial Targets Squadron, remotely pilots a QF-4 during a Combat Archer mission May 12, 2015 at Tyndall Air Force Base, Fla.

QF-4s were retired in 2016. They are now flying the QF-16.


Why is the position of the pilots' head (eyes) so important?

The correct seating position is important to ensure

A consistent viewpoint, which results in the final approach and flare always looking the same to the pilot. This is important when hand-flying the aircraft to ensure consistent landings.

Having a consistent viewpoint gives several operational advantages such as easing the handling of the aircraft by providing pilots with a consistent visual reference, repeatable at every flight. This is especially useful during final approach to be familiarized with the final approach path angle and also for the flare phase.

Best forward visibility, which maximizes the area in front of the aircraft you can see (Visual Segment):

Having the seat further backwards or lower would reduce the Visual Segment.

Good View of the Instruments, which allows seeing the PFD and ND without having to move your head down. This is how it looks with the correct seating position:

And this is how it looks if you are seated too high or too far forwards:

All sources: Airbus - Are You Properly Seated?

You also asked

Can't a pilot tell if they see enough, above/below/on each side, by just looking?

Yes, not all aircraft have the three balls for finding the optimum seat position. You can do it by looking over the glareshield and ensuring good visibility of the PFD/ND. On Boeing aircraft, this is how it is supposed to be done since they don't have a dedicated eye reference indicator:

Pilot Seat Adjustment
Adjust the seat position with the appropriate controls to obtain the optimum eye
reference position. Use the handhold above the forward window to assist. The
following sight references are used:

Sight along the upper surface of the glareshield with a small amount of
the airplane nose structure visible (A)
Sight over the control column (in the neutral position) until the bottom
edge of the outboard display unit is visible (B).

(Boeing 737 NG FCOMv2 - 1.40.44 Airplane General - System Description)


The UN charters aircraft full-time from ICAO-compliant commercial operators (the aircraft are also painted in the UN livery). So you need to be working at one of those airlines/operators the UN chooses, and then it will depend on that employer's internal policy.

To fulfill its mission, UNHAS uses a fleet of more than 90 aircraft, including helicopters, chartered from commercial air operators (...) (UNHAS)

For example, ET-ALJ (shown below) has been with Ethiopian Airlines since 2003, and it is now chartered to the UN since Aug 2020. Another example is VP-BOW, a currently Nordwind Airlines 737-800 that was chartered to the UN 2017–2018, and is now back in regular Nordwind service.

— https://www.jetphotos.com/photo/9937427

See also: Wikipedia: United Nations Humanitarian Air Service


What impact did the Concorde have on business of other sub-sonic airliners?

A few thoughts:

The British Airways Concordes only operated scheduled on the London Heathrow- New York JFK route. This implies this is the route under the most competition. There has been enough pressure on this route even after the demise of the Concorde for several companies (as well as BA) to try business-only services on this route.
By experience, changing flights is never quick in the US since you need to go through customs and add time margin to ensure you make the connection (Think three hours connection time on the ground). I think even before the current security state you'd rather have taken a direct flight than change from a Concorde to a domestic flight if possible.
I don't think the charter destinations would have caused much impact on other airline operations.


Why do Czech Airlines have the airline code (IATA airline designator) "OK"?

It starts with the International Telecommunications Union, which assigned radio call sign prefixes for each country in 1927. The OK prefix was assigned to Czechoslovakia. Other than the largest countries (US, USSR, UK, France, etc.) there seems to be no specific pattern to the assignments. When ICAO assigned aircraft registration prefixes for each country it usually based them on the ITU prefixes. In 1947, when ICAO assigned 2-digit airline identifiers they chose to use the country’s registration prefix for Czechoslovakia’s flag carrier. IATA originally based their airline ID’s on ICAO’s 2-letter ID’s. In 1982 ICAO changed to their current 3-letter format.


Who checks that pilots have their licenses?

Just as people can go for quite a while driving without a license before they get caught, there is no certain way to catch somebody who goes flying without a license.  There are various ways that it can happen, but none of them are certain.

There was a quip quoted elsewhere referring to the high proportion of unlicensed pilots in Alaska, that supposedly the FAA had a goal of getting at least half of them licensed.  I have no idea how much, if any, truth is behind that statement.

On the other hand, just as having a license can make various things you might do with a car easier or possible, there are plenty of instances where having a pilot license is necessary:

Renting a plane
Buying insurance for a plane you own (without a convincing story of who else would be flying it, at least)
A "ramp check" by an FAA inspector
Getting a job (from a reputable company, at least) as a pilot

If you file a flight plan for your flight (required for IFR -- mostly, not required but very highly recommended for VFR), part of that is to provide a name for the pilot.  But that's it, just a name, not a license number.  (Phone number, yes -- so they have somebody to call in case you're overdue so they can see if you simply forgot to close your flight plan.)  I don't know how often that info would be checked against any database of current pilots, but the potential would be there.  But the ways the FBI would find people in an investigation is wildly different from what's routinely done by Flight Service.

So if Farmer Joe (licensed) owns an airplane & his (unlicensed) brother Fred flies it every now and then from their private dirt strip, the chances of Fred getting caught are probably pretty slight, unless something goes pretty badly wrong.  And, depending on Joe and Fred's tolerance for risk, they might be entirely okay with that scenario.

Me personally, there's no *%#@ing way I'd be party to any such arrangement, but I'm probably more cautious than some Alaska bush pilots that way!  This thread discusses the consequences for flying without a license.


How does a combat aircraft handle the recoil force of a mounted gun?

In case of combat aircraft, the guns are hard mounted on the fuselage (or wings, for that matter) so that the recoil force is distributed throughout the body. In this case, the large aircraft mass acts to reduce the effects, though if the gun has too much recoil, it can cause damage to the aircraft. For example,

  The MiG-27's GSh-6-30 cannon didn't prove particularly useful in practice. It was an impressive weapon in principle, ..., but the recoil -- about 5.5 tonnes (6.05 tons) -- still had a tendency to inflict damage on the aircraft. ... Landing lights almost always broke after firing,

In case of smaller aircraft or drones, you can chose a gun with lesser recoil. Or the drone (for example) could be programmed to fly back to its original position as a way of 'absorbing' the recoil.

Another way is to mount the gun on stabilization platform, which makes sense only if the gun is quite small. A few such systems exist, which usually use robotic stabilizers to reduce the effects of the recoil due to the gun.


What prevents a commercial jet from electronically "resetting" the way a computer sometimes does?

I'm a programmer and private pilot, so maybe I can help dispel some of those fears.

The computers that run a commercial airplane are conceptually much simpler than the one that runs your phone. This means far less chance of a bug in the software, just because there's less for the programmer to keep track of.
If your phone restarts, it doesn't imperil anybody's life. So, the testing and Q.A. for such a device is basically whatever the company wants to do. On the other hand, computers in aviation are much more thoroughly tested before they can be certified to fly.
Similarly to point 1, the computers on an airplane each have only one job. A lot of the crashes on a typical PC or smartphone come from different apps stepping on each other's toes. (The operating system is supposed to keep each app apart so they can't do that, but point 2 applies to operating systems as well.)
The airplane isn't one single computer, like your phone. Yes, your phone probably has multiple processors, each with multiple cores, but they're tightly coupled together in order to form one computer. The computers on an airplane are networked together, but they are separate computers. If your phone crashes, even if the guy sitting next to you is on the same network, it doesn't affect him, does it? Similarly, if the FADEC for one engine fails (a vanishingly rare occurrence, because FADECs are conceptually among the simplest of computers), all that will happen is that one engine will shut down, with no effect on the rest of the plane.
On the other hand, the really important computers (such as fly-by-wire controllers) have multiple redundancies. So, if one fails, the rest of them can pick up the slack. Even the pilot wouldn't notice except for the warning light that would show in the cockpit.

If you want to see what actually happens when things fail on an airplane, take a look at the following videos:

Complete avionics failure over the ocean.

   The pilot flew the airplane by hand while he shut down and restarted the avionics. The flight then proceeded normally.

Autopilot failure. (Ironically, the same guy as the previous link!)

   The pilot actually let the autopilot have it for a few seconds, just out of curiosity as to where it would take them. But once it started banking more than it was supposed to, he disengaged the autopilot and took over manual control with no issue.

Brand new pilot (less than 60 hours total flying time) suffers complete electrical failure at night

   Engine stayed running despite losing all electrical power to the entire plane. He landed safely.

Edit: Well, just two hours ago as I type this, another video of an in-flight failure just happened to pop up in my YouTube feed:

Generator failure in flight

   He switched to his backup generator, and other than an annoying whine in the headphones, had no other issue with the flight.


What is the "No Step" flap thingy used for on an A320 engine?

It's a vortex generator explained in full in this question

"NO STEP" means don't put your foot on it. It's too weak to hold a person's weight and would get damaged.


How does scaling of UAV size impact range?

If you compare geometrically similar aircraft, the larger one will have more range.

First, its volume grows by the third power while areas grow only with the square of its scale, so wing loading will be higher for the larger aircraft. This will translate into a higher cruise speed, because the range optimum dictates an optimum speed for each aircraft. In a first order approximation, an aircraft of twice the size will fly at 1.41 times the speed of a smaller aircraft. The much higher internal volume will allow it to carry much more fuel, but even when the fuel fraction for both designs is kept constant will the larger aircraft fly farther.

If we restrict fuel to the same fraction of total mass, the exponent for mass increase is slightly above 2. All surfaces grow by an exponent of 2, but the stresses would be higher in a linearly scaled structure, so the structure of the larger aircraft needs no be beefier. An exponent between 2.2 and 2.3 has been found to best represent reality. This means that doubling dimensions will result in a mass increase by a factor of 4.76. In order to fly at the same polar point, the large aircraft needs to fly at 109% of the speed of the small aircraft.

In a more detailed analysis, we need to first look at the installed power: If we focus on piston engines and scale the engine in the way we scale the aircraft, for a size increase by a factor of two will the displacement grow by a factor of eight while the engine speed will decline by a bit less than a factor of two. The smaller engine will have higher friction, thermal, sealing and combustion losses, so it will have a noticeably lower efficiency. If we just look at statistical data, power output grows slightly less than linearly with displacement:

Statistical data for power over displacement. Source: Menon, S., and Christopher P. Cadou. "Scaling of Miniature Piston-Engine Performance, Part 1: Overall Engine Performance." Journal of Propulsion and Power 29.4 (2013): 774-787

Next, we need to look at Reynolds number effects. The larger aircraft will fly at a higher Reynolds number for two reasons: Increased length and increased speed. Together, a doubling in length will translate into a first-order Reynolds number increase by a factor of 2.18. The coefficient of friction will scale with Re$^{-0.3}$, so doubling the length of an airplane will reduce the friction coefficient of the large airplane to 79% of that of the small airplane. This will not only affect total drag, but also the polar point for best range. Since the optimum lift coefficient is proportional to the square root of zero-lift drag, the optimum lift coefficient for the large airplane will only be 89% of that of the half-size airplane and cruise speed will be higher by a factor of 1.225. This means that dynamic pressure is higher by a factor of 1.5.

Ideally, this calculation needs to be iterated, but for now I keep it at one iteration step.

This higher dynamic pressure now needs to be multiplied by the increase in reference area to arrive at the zero-lift drag: 1.5 times 4 times 0.79 means that doubling the size will let zero-lift drag grow only by a factor of 4.74. Since zero-lift and induced drag are of the same size at the optimum cruise point, the same factor applies to the total drag. The required power, however, is proportional to speed, so doubling the size will increase the power demand by a factor of 5.78. This is well below the power increase from a scaled-up engine, so the larger aircraft actually needs a proportionally smaller and lighter engine, leaving more reserves for fuel. Or it can scale up the engine linearly and load proportionally more fuel.

Fuel consumption is proportional to engine power, but we get another advantage from the larger engine: Its specific fuel consumption will be slightly better:

Specific fuel consumption over displacement (same source as figure above).

In sum, the larger aircraft will

cruise at 122.5% of the speed of the small aircraft
will consume 5.5 times as much fuel per time for a mass increase by a factor of 4.76. Combined with the speed increase this leaves only a 5.5% advantage.
If we assume a scaled-up engine with an increased power by a factor of 7.27, the mass increase can be by a factor of 6 with maybe twice the fuel fraction of the smaller aircraft and 7 times higher fuel flow per time. This takes into account that the cruise speed will grow with aircraft mass.

This 70% longer flying time coupled with the then 24% higher cruise speed will leave the smaller aircraft in the dust.


Why did the Daimler-Benz DB 605 compression ratio vary between cylinder banks?

The 605 (601E above) used a "wild" valve timing. This valve overlap would start letting in the air/fuel mixture, while the exhaust valve was still open. So the intake would help push out the exhaust. This hurts the low RPM performance, so a special low-speed intake was also added.*

This overlap, the rotation direction, the compressor (supercharger) being closer to the left bank, are some of the reasons that resulted in the right bank having a lower compression ratio than the left. This affected the 603 and 605, but not the 601 because it didn't have such a wild timing overlap.**

But isn't compression ratio constant due to the fixed volume (a reply to a comment):

No, dynamic compression ratio is a thing that is affected by valve timing. An example (not 605 related) is given as:

  However: intake valve closure (sealing the cylinder) always takes place after BDC (bottom dead centre), which may cause some of the intake charge to be compressed backwards out of the cylinder by the rising piston at very low speeds (...)

* enginehistory.org

** ww2aircraft.net (translated from another link)


If commercial airliner cabin is depressurized, are pilots protected against it in any ways?

No, the cockpit is not separately pressurized. That would be impractical and not particularly useful.

However, pilots do have oxygen masks, just like the passengers. Unlike the passenger masks, these masks are generally designed to be donned extremely quickly, with one hand (they tend to have automatic straps that clamp on without needing to be manually adjusted). The masks also have a separate oxygen supply from the passenger masks, and have much more oxygen available for each mask, and have other nice features. Furthermore, when one pilot is off the flight deck, the other wears an oxygen mask that's either releasing oxygen or set to automatically do that if the plane depressurizes.

If sudden depressurization happens, there are still a few seconds of useful consciousness for most people. That time is enough for airline pilots to put on their masks. Once the crew has on oxygen masks, they can control the depressurized plane just fine (depending on how it depressurized, of course: if the tail broke off, there's not much that can really be done).


What precautions should I take when flying over a mountain?

When flying over mountains Pilots will have to encounter unpredictable winds, high density altitude, steeply rising terrain and box canyons, mountain waves, rotor clouds, turbulence, and clouds covering high ground .

http://www.swaviator.com/html/issueAS99/basics.html

It is therefore essential to take the below mentioned factors into consideration :

(1) ROUTE PLANNING : When flying over mountains Route Planning is extremely important because a straight line between two points may not always be the best way to go . Therefore, pick a route that avoids the rugged areas and highest peaks where an emergency landing could not be made. It usually takes very little extra time to bypass the most mountainous areas and follow major roads through more populated areas and lower terrain .

Do not approach a ridge until you have sufficient altitude to cross with a safety margin. If you encounter too much sink, you must have enough altitude to turn away towards lower terrain. To make that turn as easy as possible, its wise to turn your aircraft to a 45-degree angle to the ridge before you cross .

http://www.avweb.com/news/airman/190015-1.html?redirected=1

(2) THE TERRAIN FACTOR : The rising terrain will often out climb non-turbocharged aircraft. If your aircraft has a service ceiling of 14,500 ft., that is based on standard atmospheric temperature which is 59 °F at sea level and decreases an average of 3.5 °F per thousand feet. If the surface temperature at 5000 ft. is 100 degrees, the density altitude on the ground is about 9,000 ft. When you climb to an indicated altitude of 9,500 feet you have reached the service ceiling of you aircraft.

(3) THE WIND FACTOR : In a light aircraft, it is best to stay on the ground if the winds are greater than 35 miles per hour. Due to the venturi effect, winds will be much greater in the vicinity of mountain passes. Cross passes as high as possible, as downdrafts up to 2,000 feet per minute can occur on the leeward side.When strong winds of 40 to 50 miles per hour are blowing perpendicular to a mountain range, expect mountain waves and strong downdrafts for many miles on the leeward side.

(4) THE CLOUD FACTOR : The combination of rising ground and lowering ceiling can be deadly. Mountains disappear not only in clouds, but also at night. You should not fly over high territory after sunset unless you are at the minimum en route IFR altitude which provides a 2,000 ft. clearance along airways. When flying after dark, closely monitor your altitude and when in a turn, your rate of descent.

A mountain checkout flight is all that is required to get started. The checkout will enable you to operate around some pretty impressive terrain :

Flatlander Focus : Two good books on the market are The Mountain Flying Bible by Sparky Imeson, and Flying the Mountains: A Training Manual for Flying Single-Engine Aircraft by Fletcher Fairchild Anderson. Reading either one will give you a solid foundation on which to build your skills.

Most Importantly - Know Your Aircraft & Its Limitations

http://www.caa.govt.nz/safety_info/GAPs/Mountain_Flying.pdf

(a) What distance over the ground does your
aircraft cover in a rate-one turn?

(b) What’s the distance for a steep turn?

(c) What speed and configuration do you use for reduced
visibility and for a minimum radius turn?

(d) What is the best-angle-of-climb speed?

(e) Do you know the manoeuvring speed (VA) and
understand its application in potentially
turbulent conditions?

(f) How is your aircraft performance and handling affected by
altitude and turbulence?

(g) How is performance affected when operating at
maximum-all-up-weight?

Needless to say recent practice and currency are vitally important.


Why do planes not fly "backwards" (up from the planes POV) when in a vertical climb?

Short answer: Yes. But only for a moment.

As you suggest, let's focus on the 90° case, because many things will become simpler. Intermediate climb angles can be covered by a linear superposition of horizontal and vertical flight.

Now we shoot up at 90° flight path angle (engine thrust permitting) and leave some angle of attack for the wing to create lift. Lift acts orthogonally to the local flow direction, so the lift will pull the aircraft sideways (up in the aircraft's frame of reference). Since there is no other force which will oppose this lift (drag, weight and thrust all act at 90° to the lift, parallel to the flight path), the aircraft will accelerate sideways (again, up in the aircraft's frame of reference). The angle of attack will immediately decrease and lift creation will stop — or the pilot forces the angle of attack to stay constant by pulling the elevator, and now the aircraft will further increase its flight path angle.

That is a complicated way of saying that the pilot forces the airplane into a loop. If he wants to maintain this 90° flight path angle, he better avoid creating any lift.


Why do NOTAMs consist of code instead of plain language?

The NOTAM format is from the time when people still would call the value of individual bits over a phone line.

Ok, that may not have happened, but my point is that data transfer was incredibly slow compared to current day standards. Therefore a compact format saved significant  transmission time and cost without losing any information. The format didn't change since.


Calculating lift with lifting-line theory in MATLAB

Your general formulation seems fine. Two things to point out:

If you choose to sample only half the wing, then you cannot utilize the relation: $C_L=A_1\pi A$. You would have to do the integration: $C_L=\frac{2}{V_\infty S}\int^{b/2}_{-b/2}{\Gamma(y)dy}$. That being said, maybe you can simplify the expression and get a closed-form result? Haven't tried myself.
Your code doesn't seem to handle for the case where $\sin(\theta)=0$.

You can take a look at the code below for reference:

% Wing area, span, chord etc.
S = 0.8; % [m^2], wing area
b = 1.56827; % Wing span
s = b/2; % Semi-wing span
taper = 0.25;
Cr = S/s/(1+taper);
Ct = taper*Cr;
MAC = 2/3*Cr*(1+taper+taper^2)/(1+taper);
AR = b^2/S;

% AoA and zero-lift AoA:
AoA = deg2rad(0);
AoA_0 = deg2rad(-6.4);

% Discretization
num = 10;
[N,Ts] = meshgrid(1:num, linspace(0,pi,num));
ys = -s*cos(Ts);
Cs = (Ct-Cr)/s*abs(ys)+Cr;

% Construct linear system
B = 2*b/pi./Cs.*sin(N.*Ts)+N.*sin(N.*Ts)./sin(Ts);
if Ts(1)==0
    % Singular case, use l'Hopital's rule
    B(1,:) = N(1,:).*N(1,:);
end
RHS = AoA - ones(num,1)*AoA_0;

% Solve
A = B\RHS;
CL = A(1)*pi*AR;


Like all complex artifacts, aircraft primary structure design is an iterative process.  It begins with aerodynamicists designing the Master Surfaces of the Aerodynamic Envelope.  Structures designers then cope with the space requirements thereafter, although compromises between multiple design teams will often be needed.

A few things will be known.  We will know the intended operating envelope of the aircraft with some intended design limitations in airspeed, maximum Mach no., service ceiling, etc of the aircraft so we can calculate the aerodynamic loads on the pylon.  We also can obtain performance numbers on the engine, so we can determine the thrust loads and moments about the mount.  We also have the design load factors for the aircraft as well as crash and emergency design loads based upon aircraft certification requirements, factors of safety, etc.  From there these external loads can be computed and used in the design requirement as external loads to a 'black box', that is an as of yet determined structural assembly for the pylon.

The exact design of the pylon and associated mounts are going to depend on these figures.  Pylon design uses similar structures from OEM to OEM and its based on their years of experience designing these thing based on both expected mathematical models as well as flight test data.  Unfortunatly the exact details of how and why it's designed the way it is remain a proprietary trade secret of the OEMs and they are not likely to talk about it.  Boeing, like KFC, has a secret recipe for its wings and is not freely released to the public.  The same is true for its pylons, empennage, etc.

The basics are most new pylons will be based upon this proprietary structural arrangement used in previous designs.  The design loads and basic configuration of the parts an assemblies going into the pylon will have been calculated by a stress engineering group into sizing for the geometry of the parts to be designed.  The first pass at the assembly design will be done by the pylon group, then used as a basis by stress for sizing and this iterative process will be repeated until an acceptable design solution is found.

Ground and flight tests will be the ultimate proof of the design and also usually leads to a weight reduction process to reduce part geometry of excess material once the actual flight loads have been verified.

Your question is an interesting one and it may be more beneficial to consult with either a retired employee from an aircraft design company who worked on these structures or a scholar in aircraft design.  Your school could probably forward you on to someone like that and you can consult with them about this.

After doing so, it might be beneficial to take a trip out to an aircraft boneyard and examine an existing engine pylon on an airplane like a 737, 747, DC-10, etc.  Heck, if the airplane is decrepit enough or about to be sold for scrap, ask the manager how much it would cost to amputate an engine pylon (minus the engine!) and take it back with you for the Master's project.  You could examine it and build CAD and FEA models of the unit, then test these using expected loads for the aircraft and engine in question.  While this might not answer your immediate questions, it will provide your project with a treasure trove of information about how and why an engine pylon is designed the way it is.  You can then examine other OEM pylon design and dissect and analyze them very accurately based on this previous experience.

Hope that helps!


Does the pilot still have final control authority on modern Boeing airplanes?

I think you fell for a common misunderstanding:

Fly by wire ≠ flight control augmentation

It is - in the first place - another method to get the pilots input out to the control surface just like cables or pushrods. Just not mechanical but electric/digital.

If you want to alter the pilot input for whatever reason it is way easier with digital signals then with a mechanical input.

Example: The speed brake in an A320 vs in a B747. If you rapidly extend the speed brake in an A320 aircraft, the extension rate is limited by a computer making for a smooth movement of the control surface. If you do the same in a B747 the system tries to match the lever position as fast as possible with all available hydraulic power (3000 psi). So rip on the speed brake lever in a B747 and the heavy aircraft will jolt quite a bit.

Concerning flight control augmentation it really boils down to the design philosophy. In a B747 you can do basically whatever you want (even stalling) but in the B747-8 you have some systems augmenting pilots input. Tail strike prevention on rotation and the nose down trim when flying a flaps 30 approach come to mind. I can't speak for the B787 but the B747-8 is, despite its largely fly-by-wire architecture, still a conventional airplane with (almost) full control authority by the pilots.

The B777 family brings flight control augmentation to the table where the computer shows you the limits via the control forces generated in the control column. The computer shows you where it thinks you should stop but if you decide to press on you just have to double the force exerted on the control column and the aircraft will do what you want.

The Skybrary has a good primer article on flight control laws for both Airbus and Boeing designs. It gives a good overview about the similarities and the differences in design and philosophy. Shoutout to user Simon Opit who brought it up.


HEPA filters, airliner HVAC and COVID 19

The air that enters the cabin of an airliner usually comes from a mixing manifold, like e.g. shown here for the Boeing 737:

(Boeing 737 NG FCOMv2 2.31.7 Air Systems - Air Conditioning System Description)
There are three ways to supply air to the mixing manifold:

From the PACKs (Pneumatic Air Cycle Kits): these are the air conditioners on the aircraft, which are supplied by hot and high pressure bleed air (either from the engines, the APU (Auxiliary Power Unit) or via an ASU (Air Start Unit) on the ground). During flight, the engines supply the bleed air to the PACKs, which results in fresh air entering the cabin.
From the Ground PCA (PreConditioned Air) hose: here the air conditioner is on the ground (usually in the airport building) and it supplies conditioned air to the mixing manifold while the PACKs are still off. See also What is this tube connected to a 757 for?
From the Recirculation Fan: here air is taken from the cabin and the fan returns it into the mixing manifold. You can see the filter in the diagram in this related answer in front of the recirculation fan, which is the HEPA filter preventing the spread of a virus via the mixing manifold. Even in flight, some air is always recirculated to reduce the required amount of bleed air from the engines.

Your question seems to focus on the time where the aircraft has already left the gate (so ground PCA is out of the question), but is still on the ground. At this time, the engines are usually running, so they could supply fresh bleed air to the PACKs. For longer waiting times, the engines are usually switched off to save fuel, but the APU would be running to power the aircraft. The APU could then also provide fresh bleed air to the PACKs.
As the quote from quora you included shows, this bleed air is not always of the best quality on the ground. It can therefore be switched off by the pilots. The following picture shows the bleed air panel of a 737-800:

(Boeing 737 NG FCOMv2 2.10.2 Air Systems - Controls and Indicators)
At the bottom are the bleed air switches for the engines and the APU. When they are switched off, the only source of air into the mixing manifold is the recirculated air. So in this case, you are already running on 100% recirculation, which is then HEPA filtered. Since the air does not go through the PACKs, it is not conditioned though, so it will get hot and stuffy in the cabin.
The top row of switches on the panel are for the two recirculation fans. They can also be switched off, in which case no air would enter the mixing manifold any more. This would make the cabin even more uncomfortable on the ground and of course also remove any HEPA filtering.


Why is cabin pressure increased above ambient pressure on the ground?

Short answer

The purpose of pre-pressurization is to avoid discomfort for passengers and crews during takeoff and landing.

By storing air in the cabin before the aircraft rotation or landing, the pressurization controller is able to smooth out:

The variations of bleed air supply when the engines deliver the highest thrust and need all available air.
The variations in both air supply and air release, due to the aircraft leaving or entering the ground effect. In particular this ground effect would force air into the cabin through the forward outflow valve when the angle of attack is increased for takeoff rotation or landing flare out.

However pre-pressurization involves relatively limited pressure differentials.

236 ft for a B737-NG (9 hPa).
140 ft for a Dash8-200-300 (5 hPa).

The case you mention seems ways higher with 40 hPa.

Pressurization system

The source of cabin air for the aircraft is commonly bleed air from the engine compressor stages. Air is sent to packs for conditioning and enters the cabin (see a more complete description in this answer):

(B737-800, source)

Bleed air pumped into the cabin then escapes it by one or two configurable exits, the outflow valves:

Outflow valve (and near to it the safety valve) on a Boeing 737-NG. Source

Cabin pressure is obtained by controlling the rates the air enters and leaves the cabin. This is indeed the job of the pressurization controller. This job is more difficult at takeoff and landing:

Air taken from the compressor is not used for the production of thrust, which can be a problem when thrust is critically required, e.g. for takeoff roll and rotation, or go-around. For these sequences, bleed air may be not available, or may be delivered at reduced or unstable rates. Normal bleed air delivery capability is restored after takeoff when the engines need less air.
The ambient pressure around the aircraft is subject to variations when the aircraft rotates and leaves the benefit of the ground effect, and also when it enters this effect before the flare. So the differential pressure at the outflow valve varies as well as the bleed air supply, and both need to be compensated too.

Pre-pressurization

Unmanaged variation of bleed air supply or cabin air outflow create air bumps in the cabin. To avoid discomfort, on some aircraft the cabin is pre-pressurized at a pressure slightly higher than the ground ambient pressure.

The pre-pressurization occurs during the takeoff roll and shortly before landing. It creates a stock of air the pressurization controller can use to smooth out bleed air bumps.

Source: B737-800 FCOM:

  The air/ground safety sensor signals whether the airplane is on the
  ground or in  the air. On the ground and at lower power settings, the
  cabin is depressurized by  driving the outflow valve to the full open
  position.

  The cabin begins to pressurize on the ground at higher power settings.
  The controller modulates the outflow valve toward close, slightly
  pressurizing the cabin. This ground pressurization of the cabin makes
  the transition to pressurized flight more gradual for the passengers
  and crew, and also gives the system better response to ground effect
  pressure changes during takeoff.

This additional amount of pressure mustn't compromise the ability to quickly open the doors in case of emergency, so pressure differential is limited. On a B737-NG, the differential is 0.125 PSI (9 hPa). This is equivalent to an altitude 236 ft below the runway. The system has a fail-safe mode which automatically opens the outflow valves quickly after the aircraft has landed (unless the Ditching switch has been pressed).

After the aircraft is airborne, or has landed, the pressurization system releases air previously stocked, to recreate a smooth altitude increase.

For the sake of completeness: The cabin will not "climb" or "descend" as fast as the aircraft, and will have its ceiling at 8,000 ft to maintain oxygen pressure at a safe level to breath without a mask.

Cabin pressure vs. atmosphere pressure

Here is a representation of the pressure differential during a flight (with the takeoff/landing highlighted. Note the cabin (dashed line) "is lower" than the aircraft.

(Source)


Where can I find a free/cheap small airplane wing?

Wings may be tough to come by as they generally last the life of the plane and can be re-skinned/fixed if need be so they are not scrapped all that frequently. You can try a used parts dealer like this one or this one but they generally deal in air worthy parts which will not be cheap. Here is a guy parting out a 152 in FL he "has wings", you may want to give him a call and check other part out barnstormers adds.

Your best bet may be to wonder on down to your local GA field and ask some questions at the FBO or maintenance facility if there is one. Its more than likely someone has a wing or wing section that is no longer air worthy from some accident or the like. You may even just see a junked wing sitting in a field behind a hangar...

STC's are specific to part or aircraft/engine so testing on a generic wing may not be a good basis (depending on what  you are doing) you may want to get the wing from the aircraft you intend to STC.


Is it possible to "take a bullet [missile]" for another plane as shown in the movie Air Force One?

Possible and Plausible are two different things.

Is it possible to fly a fighter jet between a missile and another aircraft, and either (a) confuse that missile so it follows the fighter instead) or (b) have the fighter be hit by the missile instead of the original target aircraft? Yes.
Modern fighters are capable of maneuvering in the manner shown: they can even sustain knife-edge flight or vertical climb for a while. It's even possible that in a moment of desperation a pilot would attempt such a maneuver, sacrificing themselves and their aircraft to save their commander-in-chief.

(The G-forces involved in these maneuvers may be unpleasant or even unbearable for the pilot, but if you're committing yourself to a course of action that ends with your plane blowing up to save another plane the G-forces are probably the least of your concerns.)

It isn't plausible that such a maneuver would work - at least not as depicted in the movie.

Missiles are REALLY FAST - this footage includes several slow motion shots of an air-to-air missile as it's fired (at it's slowest relative velocity), and it's still pretty darn quick: It's gone in a few frames of high-speed footage.

For this maneuver to work the intercepting pilot would need to be in exactly the right position and exactly the right time, and perform the maneuver perfectly in order to intercept the missile: A little error in any direction - too fast, too slow, too far left, or too far right - and the  missile would fly right past them and continue on toward its target.
The intercept is further complicated by the fact that, assuming the missile is guided, both the missile and the target are maneuvering as well.
(If it's a non-guided "dumb" missile all the target aircraft needs to do is change course to avoid being hit - a maneuver that might stress the airframe a bit, but certainly less than being hit by a missile would.)

To give a little more context, the "anti-missile missile" programs have often been described as having your friend throw a baseball over the roof of your house while you stand on the other side and try to hit it with a golfball as it comes over the top.
This intercept is of similar difficulty, except the balls involved are all steering themselves toward different objectives.


Is someone holding an EASA PPL (A) allowed to operate a "November" registered aircraft in Europe?

This is regulated by the FAA in FAR 61.3 and local regulations specific to each country

  (a) Required pilot certificate for operating a civil aircraft of the
  United States. No person may serve as a required pilot flight
  crewmember of a civil aircraft of the United States, unless that
  person:

  (1) Has in the person's physical possession or readily accessible in
  the aircraft when exercising the privileges of that pilot certificate
  or authorization—

  (i) A pilot certificate issued under this part and in accordance with
  § 61.19; (ii) A special purpose pilot authorization issued under §
  61.77;

  (iii) A temporary certificate issued under § 61.17;

  (iv) A document conveying temporary authority to exercise certificate
  privileges issued by the Airmen Certification Branch under § 61.29(e);
  or

  (v) When operating an aircraft within a foreign country, a pilot
  license issued by that country may be used.

To operate a US-registered aircraft you either need an FAA license or a pilot license issued by the country where the aircraft is operated in. This also means that you are not allowed to fly into another country, unless you also have a license issued by that country. Even if individual countries allow foreign registered aircraft to be operated by a license holder of another (non-FAA) country, it would still be a violation of FAR 61.3.

Bottom line: if you want to fly a N-registered aircraft without an FAA pilot license in Europe, you need a pilot license issued by every country you're flying into. For example, if you plan a trip from The Netherlands to Portugal you would need 5 different EASA PPL licenses issued by The Netherlands, Belgium, France, Spain and Portugal.


Report here states it is suspected to be due to foreign or domestic object damage (FOD/DOD).

Provided with the photos taken of the NZ99 engine after it landed back in Auckland, a spokeswoman said: "The cause of these incidents is yet to be determined and this is the role of the Transport Accident Investigation Commission. But the damage sustained on Tuesday suggests an engine part has travelled through the engine."
An aviation source told Newsroom: "The damaged blades are in the aft section of the turbine blade sections. It is likely the damage has resulted from a failure of a turbine blade or blades in an earlier section that has been spat out the back with a domino effect.”

I would suspect an over temperature and/or excessive vibration may also have occurred. It seems similar to the damage in these two events, which featured those events:
Boeing 777-200, GE90, Dec 2010.

The damage pattern leads to the suspicion that one or more fuel injectors in the combustion chamber behaved abnormally leading to an excessive temperature build up in the turbine area, which probably caused the LPT guide vanes material to fail. The engine manufacturer has registed six similiar failures which are all suspected to be the result of fuel injector malfunctions.

Boeing 737-400, CFM56, Nov 2009.

The in-flight malfunction of the aircraft’s right engine was a result of a cascading rupture of the stage-1 LPT blades, [which] was probably precipitated by thermal degradation of the blade alloy, resulting in excessive creep extension, tip shroud/seal interference and blade rupture. Material characteristics of some of the LPT blades installed in the engine were consistent with a raw material manufacturing cast that had previously been identified as being susceptible to creep rupture.


What contra-rotating propellers would be appropriate for this engine?

Contra-rotating props correctly address the problem of how torque
complicates the steering of a PPG.
(To solve this, others have even powered PPGs with large "quadcopters"
where two of the four props are counter-rotating,
despite the screaming of four small fast props.)
In conventional aviation two contra-rotating props typically have the
same diameter and pitch and speed.  For a PPG, keeping them the same size
is particularly useful to cancel torques.
To replace one prop with two, and otherwise keep everything the same,
we should not change the pitch speed or RPM, only the diameter,
to spread the thrust load evenly across both props.
The OP says that a similar engine powers a 49x28" prop at 2700 rpm.
The OP's engine redlines not much past that, so call the RPMs the same.
Then the prop pitch also remains the same, so prop diameter is the only thing left to vary.
Coaxial contra-rotating props are roughly 10% more efficient,
compared to non-coaxial props as on a conventional twin-engine airplane.
So each one of the pair has 45% of the load of the original single prop.
So each prop provides 45% of the thrust of the nominal 49x28" prop.
If all else is equal, thrust varies with the fourth power of diameter.
So we should scale the diameter of the 49x28" prop by 0.451/4 = 0.82.
So the engine should use a pair of 40x28" props.
Exactly the diameter that was guessed.


What type of mechanism is used to operate the Embraer EMB 120 front door?

From the EMB120 Ops Manual:

  FORWARD ENTRY DOOR

  The forward entry door incorporates a folding air stairs and is fixed
  at the fuselage's lower edge.

  The door can be raised manually or hydraulically. For normal
  operation, two hydraulic actuators powered by the green hydraulic
  system or by an accumulator, raise the door. This actuator has the
  capability of performing four complete operations and is controlled
  from the INTERIOR FWD DOOR CONTROL PANEL (ATTENDANT'S PANEL) or from
  EXTERIOR FWD DOOR CONTROL PANEL. Each panel incorporates a pushbutton,
  which energizes a solenoid valve that allows hydraulic power to raise
  the door. A blue light illuminates while the door is moving up. This
  system's circuit breaker is located at the INTERIOR FWD DOOR CONTROL
  PANEL (ATTENDANT'S PANEL).

  The door may be raised manually by an outside ground attendant who
  lifts the door to its closed position.

  The spring accumulator is located in the hydraulic compartment at the
  right side of the fuselage forward section. Once the door is raised,
  moving the red inner or outer handle down will latch it. The hydraulic
  circuit provides a damping function when the door is opening.

  The hydraulic circuit is provided with an emergency valve, which
  allows the forward door to be lowered when the solenoid valve fails.


The curently operational GE90-115B engine is somewhat more powerful than the listed specs I've seen for the GE9X, at 115,540 lbf thrust vs just 105k.

That engine powers three current variants of the 777. Interesting to note that the 777-300ER is actually 5% heavier than the original 1966 version of the 747. Two of the 90-115 also have more takeoff thrust (~230k lbf) than the original 747-100 (~175-205k lbf).

So, in theory, two modern engines can power a 747, but only the original, not the 747-8.

Twins have higher thrust requirements, as they have to be able to take off with just one engine, while quads can use three. The 741's wings aren't as effective as the 777's, so even the 741's 5% lower weight might not quite suffice. But as the "741-twin" could use less fuel than the original, it could still maintain the 741's original payload and range.

There are other changes required for a twin and for ETOPS, so it won't be just a re-engine. All in all, a twin-powered aircraft with the early 747's fuselage, general layout and performance, but some control modifications, should be possible.

The 748 is a much heavier aircraft than the 741. It could in theory be ferried with the power of two GE9x engines, but its total weight would have to be restricted to less than that of a 741. That cuts its useful load in half - essentially, half the aircraft is now useless.

If operated, it wouldn't be able to fill all its seats or fly its full range. Such an aircraft would have no value for commercial operations. The only uses for it I can think of would be an oversized vomit comet or carrying something extremely light. And there are special aircraft with oversized fuselages for that like Airbus Beluga or Boeing Dreamlifter.

The minimum a modified 748 could operate commercially with is three modern engines. With two out of three GE9x running it would get 210,000 lbf of thrust, which is marginally above the 200k that three of the 748's engines produce.

TL;DR version: Two GE9x could keep a 748 in the air, but not in the black.


Simply put, it's supposed to follow a constant flow/fanspeed curve but multiple stages and the mechanics of surging make it a lot more complex in practice.

  The surge line slope on multistage compressors can range from a simple, single-parabolical [sic] relationship to a complex curve containing several break-points or even 'notches.'  The complexity of the surge line shape depends on whether or not the flow limiting stage changes with operating speed from one compression stage to another; in particular, very closely matched stage combinations frequently exhibit complex surge lines... The surge line in many cases has an approximately constant value of Q/N [mass flow/fan speed].  In many multi-stage units, and especially in units which are controlled by variable inlet guide vanes, the surge line curves bend dramatically at higher flows and speeds.Source: "Practical Aspects of Centrifugal Compressor Surge and Surge Control" by  Meherwan P. Boyce (pdf)

So some of the shape comes from the curvature and irregular spacing of the constant speed lines, and some of the curve comes from adding in different stages.

Unfortunately, exact surge conditions are not easy to describe mathematically even if we know the properties of each stage in the compressor.  There are things like multi-blade interactions and boundary layer effect that make things difficult really fast.  These factors are so important because surge is not quite the same as a stall on compressor blades.  Surge is a more complex unstable compressor flow resulting from stalls. Single blade stall, which isn't observed much in practice, will not cause a surge.  Surge happens when the stall propagates across several blades due to blocked incoming air.  There aren't easy,exact, and universal equations for this complex behavior unfortunately.


A listening squawk is a transponder code you set to indicate to an ATC controller that you are listening out on a particular frequency.

Unlike squawk codes assigned by the controller, the listening squawk is not unique to your aircraft but is a set (and published) code for the particular area. In the UK it is commonly used in the uncontrolled airspace around a major airport's terminal control area.

Examples in the UK include the airspace surrounding Luton, Stansted, Leeds, and one dedicated to the narrow "low level corridor" allowing VFR flight between the class D airspaces of Manchester and Liverpool.

The procedure is: after signing off from whatever facility you were previously in contact with, set your com radio to the assigned listening frequency and set your transponder to the published listening squawk. Do not contact the controller, instead listen out for any broadcast which may be intended for you (eg the controller may ask the aircraft in a particular location to respond). They will know you are on frequency because of the code you are squawking.

The controller will generally only attempt to contact you if you are about to violate controlled airspace or have a traffic conflict. Note that this should be treated as a backup only, the responsibilities for navigation and see-and-avoid remain as ever with the pilot.

Once out of the area, or when you need to change frequency to your destination or next enroute contact, turn the transponder back to the VFR conspicuity code 7000.

If I recall correctly my instructor told me that this is a UK/CAA-specific initiative and is not found in other countries.


Can I use my aviation handheld transceiver on MURS?

You asked for legal opinion, so the main "legal" reason would be that a radio must be type-accepted for the service for which you want to use it. So unless Icom A-24 is MURS type accepted, and it is not, then it's illegal to use it.

You don't need a special FCC license. FCC says this about licensing:

  MURS is licensed by rule. This means an individual license is not
  required for an entity to operate a MURS transmitter if it is not a
  representative of a foreign government and if it uses the transmitter
  only in accordance with Section 95.1309. There is no age restriction
  regarding who may operate an MURS transmitter.

But the transmitter itself must be marked as MURS transmitter. FCC has this to say about that:

  A MURS transmitter must be certified by the FCC. A certified MURS
  transmitter has an identifying label placed on it by the manufacturer.

There is technical reason as well which makes it impossible to use it on higher VHF frequencies: Above 137 MHz, the traditional modulation type is FM. Aviation VHF is AM. So even if you wanted to talk to MURS users, you wouldn't be able to do so normally due to different modulation types used. Another technical issue is frequency coverage. A-24 can transmit 118.000 MHz to 136.975 MHz. I don't know if it's possible to unlock it for extra coverage (but I'd be surprised is that was possible, due to use case), but with default frequency coverage you can't go high enough to reach MURS frequencies.

UPDATE:  I just checked and it seems that AM is actually allowed on MURS. So it is, and you can somehow unlock the A-24 to operate on those frequencies, you could technically speak to other AM MURS users, but again it wouldn't be legal due to licensing system used for MURS.


Why are liquid ring compressors not used in a jet engine?

You said to ignore the cooling of the liquid, but that's something that cannot be ignored.  With the compression ratios achieved in typical jet engine compressors, the air leaving the last stage of the compressor may be 800 - 1000 deg F.  You won't find a lot of liquids that won't just completely vaporize at those temperatures.  Yes you could potentially cool the liquid, but the cooling apparatus would add a huge amount of weight, as well as consume a lot of power.


How does an AMRAAM communicate securely with the aircraft that launched it?

Do you have a need to know?

Fortunately, there is a simpler answer to your question: the original AMRAAM does not communicate with the host aircraft. Only the host aircraft communicates data to the missile. This data is transmitted in the form of fixed-format messages, repeated multiple times with redundancy.

Security would fall outside the scope here, except in most general terms. In general terms, when secured, unidirectional datalinks use fixed key symmetric encryption. A missile's downlink isn't necessarily secured, as it's only transmitting the enemy's position for guidance correction.

Newer and more complex missiles that do communicate bidirectionally typically use Link 16. That is a secure encrypted protocol. It's well-documented and you can find a fairly good overview of the protocol on the net.


Yes, it is legal to fly above Vatican City, but not below 2500 FT if flying IFR or 3500 FT if flying VFR.
There are several Prohibited Areas established over Rome. Prohibited area 212, mentioned by @JanHudec, is not actually above Vatican City, instead it is there to protect the Regina caeli prison.
However, there is a prohibited area covering the Vatican City: P243, in which IFR traffic is prohibited below 2500 FT and VFR traffic is prohibited below 3500 FT. The AIP (ENR 5.1.1-14) notes that the area is "subject to overflyng restriction for security-safety reasons". While not mentioned directly in the AIP, presumably, there is a way to get permission to fly into the area in special cases, for example to access the Vatican City Heliport.

The red area in the image above shows prohibited area 243. Marked with blue is the heliport.
There appears to be no restrictions for traffic above 3500 FT. There is even an airway (L5) almost directly above the Vatican City (black line on the map), which has a lower limit of FL95 (9500 FT) - which is a completely normal lower limit of an airway, Vatican City or not - so it seems IFR traffic will routinely fly directly above, albeit not a low levels.


What is the purpose of the Boeing SCAP module?

The Standardized Computerized Airplane Performance (SCAP) interface is a standardised model for calculating aircraft performance of air transport category aircraft. The SCAP standard is developed and maintained by IATA and leading aircraft manufacturers.

From the IATA website:

  One particularly complex requirement is the calculation of takeoff performance data. Most airlines use programs supplied by the airplane manufacturers for each airplane type, and interface these programs with their own computer operating environment, airfield database, and data output format requirements.

  In order to reduce the development effort for the airlines
  (interfacing with different airplane manufacturers' programs) and
  manufacturers (meeting individual airline requirements for
  customer-specific features) there are clear advantages in
  standardizing as much as possible the input/output features of these
  programs, and also data formats.

  Having recognised this potential benefit, IATA, ATA and several
  manufacturers set up a Standardized Computerized Airplane Performance
  Task Force (SCAP TF).

A  SCAP module is a FORTRAN program that implements the SCAP standard. It takes a set of well defined inputs to produce a well defined output.

The advantage of this approach is that it is possible for a third party to design a software program that requires aircraft performance data without having access to this proprietary data. The software can then be used for aircraft performance calculations of any aircraft as long as it has access its SCAP modules.

There are 6 SCAP specifications for Takeoff, Landing, Climbout, Inflight, Noise and APM (Aircraft Performance Monitoring).

I don't have access to the official SCAP specification, but from what I can find online I gather that for take-off performance the following is required:

TODA (Take-Off Distance Available)
TORA (Take-Off Run Available)
ASDA (Accelerate Stop Distance Available)
runway elevation
runway surface condition
runway heading
wind speed and direction
ambient Temperature
QNH
MEL/CDL items affecting performance
max take-off thrust and reduced (FLX) option
anti-icing options
flap settings
V1/VR (fixed or opt)
V2/VS (fixed or opt)
minimum acceleration altitude
actual take-off weight

I gather the landing SCAP module needs:

LDA (Landing Distance Available)
runway surface condition
runway elevation
runway heading
wind speed and direction
ambient temperature
MEL/CDL items affecting performance
approach type (CAT I/II/III)
anti-icing options
presence of residual ice
flap setting (fixed or opt)
expected landing weight


A wing can be tested in any orientation as long as the load is applied correctly. The classic wing test photo is the 787 in a fixture showing its extremely flexible wings.

I thought it might be fun to add an ultimate load test, so here is the 777 tested to failure. Sorry for the early 1990s video quality.

Boeing 777 wing fail at 154% design load


Can a weather balloon move horizontally?

An ordinary weather balloon cannot maneuver horizontally (unless an external force is applied to it) because it lacks the means to do that. It has only one purpose, to soar up to the altitude where the air pressure inside is more than outside and then burst.

If you want it to steer, you can add steering servos (as mentioned in this PDF). Of course this will add cost and complexity.

There are some websites for Balloon Trajectory Forecast, which might be helpful.

Only if Larry Walters had thought about this, things would have been different for him.


Is there a service to review prior flight plans?

Lockheed Martin Flight Services (LMFS) provides a history of filed flight plans on their web site under Flight Planning & Briefing | History. The path to the particular page is: https://www.1800wxbrief.com/Website/showPilotHistory.

Unfortunately, only the last 15 days are available. So if your flight plan is older, it won't be displayed. Additionally, if you're filing your flight plans through a service provider that doesn't provide full LMFS integration (e.g., ForeFlight) it won't be displayed even if within 15 days. In this case, you'll need to refer to your service provider's interface.


Is the destination of a commercial flight important for the pilot?

The pilots in this case did know where they were going: Edinburgh.

BA said a paperwork error was to blame, with the pilot following orders from Germany, where WDL’s head office had filed the incorrect flight plan.  The pilots flew according to the flight plan they were given, and ATC happily routed their plane along that flight plan as well.  The pilots had no reason to suspect the flight plan was incorrect, and safety was never compromised.

The dispatchers involved could use improvement, though.


Yet another "Why aren't I soloing yet?" scenario

This question is pretty open ended.  As a CFI myself, I really couldn’t assess whether you are ready to solo or not until I have flown with you and seen how you are handling the airplane on takeoff, landing, and in the traffic pattern.

My general assessment standard for readiness to solo is to see the student exhibit solid knowledge and practical fundamentals for takeoffs and landings and the required airmanship needed to perform them down pat.  They can either correct for errors in the approach and landing or exercise good judgment when a go around should be executed.  Very rarely, if ever, do I need to provide technique guidance, verbally or otherwise.  The student may not yet be acceptable quality for a checkride, but the technique is solid, safe and the student is exercising sound judgment in ADM and risk management for airport operations, including go-around assessment and techniques, pattern spacing, accounting for the effects of wind, solid crosswind skills in light winds.

First off, we want you, the student, to be safe.  The last thing I want as a CFI is to grab a newspaper or turn on my TV and see an airplane crash in the news with my student’s name listed as a casualty.  Secondly the CFI is legally responsible for whatever you do on a solo flight he/she has authorized and their ticket can be on the line if anything happens and the authorities determine they are culpable.  We don’t want you guys going out and breaking the law, unintentionally or otherwise.  Third, we don’t want you to learn and ingrain any bad flying habits and techniques, particularly when sending you out on your own, so it’s best - and particularly during the pre-solo phase - that we route them out early.

Finally, everybody is in a rush to get the magic minimum number of hours to go for a checkride.  Or solo.  Or go on a cross country, etc.  We all have heard stories about people going from no experience to PPL in two weeks (drunks at a bar tell fanciful tales, too, BTW!).  We all expect to do this or better because every pilot thinks he/she is Sierra Hotel and wants to be better than the other guy.  While I can appreciate this, especially from a financial standpoint, keep in mind that that’s just the MINIMUM seasoning the FAA expects in an applicant.  Typically people are getting a PPL these days at around 70 or so total flight hours.  While the regulations provide guidelines for what an knowledge and practical skills an applicant should bring with them for a checkride, solo or any other phase of their flight training, the real answer is are they unconsciously competent at their airmanship to do it.  Like any human endeavor which requires motor control and practice we have good days and bad ones.  When your ‘bad day’ in the airplane is at or above the standards set for that phase of flight training, be it solo, checkride, or otherwise, you’re probably ready to pass.

I hope that helps.


What determines CFD accuracy for aircraft design?

CFD is a prime example for "garbage in – garbage out".
There is a large range of parameters that needs to be set correctly, from fluid properties to surface roughness. If the persons feeding the software do not understand what they are doing, it is very hard for them to judge the result. Lots can go wrong and will produce colorful but wrong results.
CFD is best suited when you know what to expect and can check the correctness with real-world data. Then it is fair to assume that the results over the whole flowfield are realistic and looking into corners that cannot be observed in an experiment makes CFD supremely useful.
Why else are wind tunnels still solidly booked and running? Today, it is mostly for validating CFD results and making sure the complex software produced realistic results.
Now I have answered your question body. Since you asked something rather different in the title: That answer follows here:
Accuracy depends on:

The code: Potential code cannot model separation, Euler codes cannot model viscosity. Navier-Stokes codes can, but still have trouble with turbulent, separated flows. For more detail, make sure to read the answer of @XRF.
The mesh geometry: It is hard to get the mesh right so solutions iterate well and results are robust.
Mesh resolution: A coarse grid (2D) or mesh (3D) will create poorer results than a fine mesh. Of course, computational load goes up with mesh size.
The domain being investigated: Subsonic, fully attached and steady state flow is easier to get right than separated flow or the exact shock position in transsonic, instationary flow.


This is about 3 videos released by the Pentagon. The vehicles in those videos don't fly extraordinarily fast. The 3 videos in question show normal aircraft and a balloon. The reported speeds are incorrect due to imperfections in the equipment used and optical illusions.


C-152 carb heat on before landing in hot weather?

You should always pull the carb heat when throttling back no matter the conditions for 3 reasons:

Ice forms from moisture (duh!), and there's much more moisture in hot tropical air than cold arctic air, so being in a tropical location does not lower the icing potential. The temperature drop is caused by the Venturi Effect which aerates the fuel in the carburetor, fuel is not frozen in the carb by the outside air temperature, you can get carb icing on a hot day
Habit: it's important to get into good carb heat habits, otherwise you may forget to pull the carb heat when you need it. Make it so automatic it just happens without conscious thought
Workload: Deciding when to use carb heat or not requires thought, you have to consider density altitude, temperature, relative humidity, the make of the carb, and other factors to make the right decision. Why add to your workload when 90% of the time you're probably going to conclude you do need it? Approach is a busy time, you should be spending time looking for traffic, maintaining airspeed and the other critical aspects of flight

It's worth reminding as well that icing can happen in cruise as well, so keep in the habit of applying carb heat regularly.


What are the ICAO fuel reserve requirements?

The following includes the changes you allude to (which were proposed in ICAO State Letter SP 59/4.1-11/8 on June 30, 2011).

Commercial Flights

Per ICAO Annex 6, Part I, section 4.3.6 "Fuel Requirements," airplanes should calculate their required fuel quantity as follows (summary; see below for actual ICAO text):

Taxi fuel
Trip fuel (to reach intended destination)
Contingency fuel (higher of 5% of "trip fuel" or 5 minutes of holding flight)
Destination alternate fuel (to fly a missed and reach an alternate)
Final reserve fuel (45 minutes of holding flight for reciprocating engines, 30 minutes for jets)
Additional fuel (if needed to guarantee ability to reach an alternate with an engine failure or at lower altitude due to a pressurization loss)
Discretionary fuel (if the pilot in command wants it)

General Aviation

For general aviation, ICAO Annex 6 Part II, section 2.2.3.6 "Fuel and oil supply" requires:

For IFR, enough fuel to reach destination, then alternate (if required), plus 45 minutes
For day VFR, enough fuel to reach destination plus 30 minutes
For night VFR, enough fuel to reach destination plus 45 minutes

ICAO Annex 6 Part I

From the ninth edition:

  4.3.6.3 The pre-flight calculation of usable fuel required shall include:

  a) taxi fuel, which shall be the amount of fuel expected to be consumed before take-off;

  b) trip fuel, which shall be the amount of fuel required to enable the aeroplane to fly from take-off, or the point of in-flight
  re-planning, until landing at the destination aerodrome taking into account the operating conditions of 4.3.6.2 b);

  c) contingency fuel, which shall be the amount of fuel required to compensate for unforeseen factors. It shall be five per
  cent of the planned trip fuel or of the fuel required from the point of in-flight re-planning based on the consumption
  rate used to plan the trip fuel but, in any case, shall not be lower than the amount required to fly for five minutes at
  holding speed at 450 m (1 500 ft) above the destination aerodrome in standard conditions;

    Note.— Unforeseen factors are those which could have an influence on the fuel consumption to the destination
    aerodrome, such as deviations of an individual aeroplane from the expected fuel consumption data, deviations from
    forecast meteorological conditions, extended taxi times before take-off, and deviations from planned routings and/or
    cruising levels.

  d) destination alternate fuel, which shall be:

  where a destination alternate aerodrome is required, the amount of fuel required to enable the aeroplane to:
  i) perform a missed approach at the destination aerodrome;
  ii) climb to the expected cruising altitude;
  iii) fly the expected routing;
  iv) descend to the point where the expected approach is initiated; and
  v) conduct the approach and landing at the destination alternate aerodrome; or
  where two destination alternate aerodromes are required, the amount of fuel, as calculated in 4.3.6.3 d) 1),
  required to enable the aeroplane to proceed to the destination alternate aerodrome which requires the greater
  amount of alternate fuel; or
  where a flight is operated without a destination alternate aerodrome, the amount of fuel required to enable the
  aeroplane to fly for 15 minutes at holding speed at 450 m (1 500 ft) above destination aerodrome elevation in
  standard conditions; or
  where the aerodrome of intended landing is an isolated aerodrome:
  i) for a reciprocating engine aeroplane, the amount of fuel required to fly for 45 minutes plus 15 per cent of the
  flight time planned to be spent at cruising level, including final reserve fuel, or two hours, whichever is less;
  or
  ii) for a turbine-engined aeroplane, the amount of fuel required to fly for two hours at normal cruise
  consumption above the destination aerodrome, including final reserve fuel;

  e) final reserve fuel, which shall be the amount of fuel calculated using the estimated mass on arrival at the destination
  alternate aerodrome, or the destination aerodrome when no destination alternate aerodrome is required:

  for a reciprocating engine aeroplane, the amount of fuel required to fly for 45 minutes, under speed and altitude
  conditions specified by the State of the Operator; or
  for a turbine-engined aeroplane, the amount of fuel required to fly for 30 minutes at holding speed at 450 m
  (1 500 ft) above aerodrome elevation in standard conditions;

  f) additional fuel, which shall be the supplementary amount of fuel required if the minimum fuel calculated in accordance with 4.3.6.3 b), c), d) and e) is not sufficient to:

  allow the aeroplane to descend as necessary and proceed to an alternate aerodrome in the event of engine failure
  or loss of pressurization, whichever requires the greater amount of fuel based on the assumption that such a failure
  occurs at the most critical point along the route;
  i) fly for 15 minutes at holding speed at 450 m (1 500 ft) above aerodrome elevation in standard conditions; and
  ii) make an approach and landing;
  allow an aeroplane engaged in EDTO to comply with the EDTO critical fuel scenario as established by the State
  of the Operator;
  meet additional requirements not covered above;

    Note 1.— Fuel planning for a failure that occurs at the most critical point along a route (4.3.6.3 f) 1)) may place
    the aeroplane in a fuel emergency situation based on 4.3.7.2.

    Note 2.— Guidance on EDTO critical fuel scenarios is contained in Attachment D;

  g) discretionary fuel, which shall be the extra amount of fuel to be carried at the discretion of the pilot-in-command.

ICAO Annex 6 Part II

  2.2.3.6 Fuel and oil supply

  A flight shall not be commenced unless, taking into account both the meteorological conditions and any delays that are
  expected in flight, the aeroplane carries sufficient fuel and oil to ensure that it can safely complete the flight. The amount of
  fuel to be carried must permit:

  a) when the flight is conducted in accordance with the instrument flight rules and a destination alternate aerodrome is
  not required in accordance with 2.2.3.5, flight to the aerodrome of intended landing, and after that, for at least 45
  minutes at normal cruising altitude; or

  b) when the flight is conducted in accordance with the instrument flight rules and a destination alternate aerodrome is
  required, flight from the aerodrome of intended landing to an alternate aerodrome, and after that, for at least 45
  minutes at normal cruising altitude; or

  c) when the flight is conducted in accordance with the visual flight rules by day, flight to the aerodrome of intended
  landing, and after that, for at least 30 minutes at normal cruising altitude; or

  d) when the flight is conducted in accordance with the visual flight rules by night, flight to the aerodrome of intended
  landing and thereafter for at least 45 minutes at normal cruising altitude.


Is there any regulation that authorizes autopilot use when cleared for a visual approach?

The general answer is no. A visual approach isn't considered an instrument approach according to ATC so there's no restriction - or direction, if you prefer - on how to fly one:

  A visual approach is an ATC authorization for an aircraft on an IFR
  flight plan to proceed visually to the airport of intended landing; it
  is not an instrument approach procedure. Also, there is no missed
  approach segment. An aircraft unable to complete a visual approach
  must be handled as any go-around and appropriate separation must be
  provided.

And from the AIM 5-5-11:

  The pilot must, at all times, have either the airport or the preceding
  aircraft in sight. After being cleared for a visual approach, proceed
  to the airport in a normal manner or follow the preceding aircraft.
  Remain clear of clouds while conducting a visual approach.

That means that when you're cleared for a visual approach it's entirely up to you how you approach and land, providing that you follow the rules mentioned in the AIM and  - in the case of airline operations - whatever procedures are detailed in your operations specification.

But if you're asking about autoland specifically (not general autopilot use) then the FAA does have a few relevant comments in their guidelines for CAT III operations:

  Autoland or HUD to touchdown operations are required for all CAT III
  operations, and many operators use autoland or HUD for CAT II, CAT I,
  and visual flight rules (VFR) operations as well. Part 121, §
  121.579(c); part 125, § 125.329(d); and part 135, § 135.93(d) prohibit the use of autoland or HUD to touchdown in any operation unless the
  operator is specifically authorized via OpSpecs.

And:

  Practice autoland or HUD to touchdown operations may be conducted at
  CAT I runways in CAT I or better weather conditions where the facility
  classification is unknown, because the flightcrew is monitoring system
  performance, visually verifying the position of the aircraft, and can
  determine whether to continue to a landing or execute a missed
  approach in CAT I or better weather conditions. Though it is not
  recommended, flightcrew monitoring and increased visibility also
  permits practice autoland or HUD to touchdown operations using an ILS
  classified as I/A, I/B, I/C, or I/T, provided the operation is
  performed in VFR conditions

I understand that to mean that autolanding is allowed in visual conditions (provided it's authorized via OpSpecs) for training/practice purposes, and since they mention autolanding use even under VFR I don't see why it wouldn't be allowed on a visual approach.


Are military and jet pilots given any extra training before entering commercial aviation if yes, then how?

Watch out for the words "centerline thrust only"!

The overall answer to your question depends on the military pilot's background and experience.  Military heavy jet pilots (bomber and transport) will have very little difficulty converting over to civil airliners, as civil airliners and military transports of equivalent role are close cousins in flight characteristics, and many bombers aren't that far off either.

Fast-jet pilots, however, can run into one specific difficulty when transferring to civil jet aircraft.  Most (albeit not all) twin-engine tactical jets have their engines mounted very close to the aircraft centerline.  This means that there is very little yaw when an engine fails in a tactical jet, which is quite difference from the response of an airliner, or even most light twins, during an engine failure.

Hence, a pilot whose sole multi-engine experience is in twin-engine tactical jets may receive a "centerline thrust only" restriction on the CPL/AMEL certificate they are issued on the basis of their military experience.  This restriction must be lifted before they can fly or receive a type rating in a non-centerline-thrust aircraft (even a DC-9 yaws enough on engine failure not to count).  Thankfully, it's not a hard restriction to lift -- in the worst case, it's simply a matter of passing the multi-engine checkride in a light twin with wing-mounted engines, and may be liftable as part of a type rating course for a non-centerline-thrust multi-engine aircraft for that matter.


Are red obstacle lights near an airport required to be lit during the day?

It's unclear exactly which lights you're referring to (none of the example pictures you linked to are red), but the FAA AC on obstruction lighting says that only structures over 200ft are required to be lighted:

  Any temporary or permanent structure, including all  appurtenances,
  that exceeds an overall height of 200  feet (61m) above ground level
  (AGL) or exceeds any  obstruction standard contained in 14 CFR part
  77,  should normally be marked and/or lighted.

However, there are exceptions:

  The FAA may also recommend marking and/or  lighting a structure that
  does not exceed 200 (61m)  feet AGL or 14 CFR part 77 standards
  because of its  particular location.

The same document describes the use of red lights:

  Aviation Red Obstruction Lights. Use flashing beacons and/or steady
  burning lights during  nighttime

The rest of the document suggests that red lights are for night use and white for day use. The FAA also has a dedicated portal for obstruction evaluation and reporting if you're involved in building or managing potential obstacles.


What is this device they bring on board from the jet bridge when we park?

It is a temperature probe for the preconditioned air (PC air) unit.

Bleed air is required in order to operate the air conditioning packs on an aircraft*. Thus, either an engine or the auxiliary power unit (APU) must remain running, burning jet fuel.  PC air pumps heated or cooled air into the aircraft and allows the pilot to shut down the engines and APU to conserve fuel.

This is what the system looks like from the outside:

A probe (located in the passenger loading bridge) is inserted into the cabin to regulate the air temperature while PC air is hooked up and running.

Upon parking, ground crews will typically hook up both ground electrical power and PC air, especially if the aircraft will be parked for any length of time. Since the air hose takes some time to unroll and roll, PC air may not be used if the flight is a "quick turn" and the APU will be left running.

* Except for the Boeing 787, which has a no-bleed system.


Can a GPS waypoint be used when filing a VFR flight plan?

Yes, nothing prevents you from doing so, and it is quite common.

Flying VFR does not require you to actually navigate by means of visual reference, it just requires you to remain VMC in accordance with the airspace class you are in.


Why aren't large, low-speed propellers widely used?

You are not wrong, it is more efficient to accelerate a large mass by a little than a small mass by a lot.

This is due to momentum being linear with speed and mass, while energy is linear with mass but quadratic with speed, so the same momentum can be obtained more efficiently by slowly pushing a large amount of air, e.g. with a large propeller.

The reasons against this are as you imagined, like clearance from the ground and other parked craft. Also, extremely long propeller blades will suffer from high inertia and bending moments, without the benefit of centrifugal stiffness. And then there is the issue of keeping the propeller tips subsonic, to avoid wasting a lot of energy in the form of sound.


What's the process for an uncontrolled airfield to become controlled/towered?

I finally found an AOPA article that discusses requirements for a control tower.

They say:

  The FAA has the authority to establish control towers or discontinue
  control tower services through the National Airspace System when
  activity levels and safety considerations merit such action.

In order to open a new tower, there must be a positive Benefit-Cost ratio (which is a complicated thing to calculate).  The FAA typically pays for the cost, and here is the criteria that they list:

  Criteria

  According to FAR Part 170.13, the following criteria, along with
  general facility establishment standards, must be met before an
  airport can qualify for a control tower:

  The airport, whether publicly or privately owned, must be open to and available for use by the public as defined in the Airport and
  Airway Improvement Act of 1982;
  The airport must be part of the National Plan of Integrated Airport Systems;
  The airport owners/authorities must have entered into appropriate assurances and covenants to guarantee that the airport will continue
  in operation for a long enough period to permit the amortization of
  the control tower investment;
  The FAA must be furnished appropriate land without cost for construction of the control tower; and
  The airport must meet the benefit-cost ratio criteria specified herein utilizing three consecutive FAA annual counts and projections
  of future traffic during the expected life of the tower facility. (An
  FAA annual count is a fiscal year or a calendar year activity summary.
  Where actual traffic counts are unavailable or not recorded,
  adequately documented FAA estimates of the scheduled and nonscheduled
  activity may be used.)

  The FARs specifically state that an airport is not guaranteed to
  receive a control tower, even if the airport meets all the criteria
  listed above. This is where the contract tower program comes in. The
  FAA, responding to an airport sponsor's request for an air traffic
  control tower, can elect to establish a contract tower. The FAA can
  either elect to pay for the service in its entirety, or enter into a
  cost-sharing agreement with the sponsor, depending on the results of
  the benefit-cost analysis. Typically, the airport sponsor is
  responsible for 10 percent of the cost of construction and operations.

For the Benefit-Cost calculation, they use the following criteria:

  Site-specific activity forecasts are used to estimate three categories
  of tower benefits:

  Benefits from prevented collisions between aircraft.
  Benefits from other prevented accidents.
  Benefits from reduced flying time.

  Explicit dollar values are assigned to the prevention of fatalities
  and injuries and time saved.

  Tower establishment costs include:

  Annual operating costs: staffing, maintenance, equipment, supplies, and leased services.
  Investment costs: facilities, equipment, and operational start-up.

The article contains a lot more information, along with links to the relevant regulations, etc.


On the A320, why is it not recommended to use the HP ground unit when the APU Bleed is on?

The uses of the HP air of the pneumatic system are in the FCOM:

  air conditioning
  engine starting
  wing anti-icing (see here)
  water pressurization
  hydraulic reservoir pressurization

The HP air sources are engine bleed, APU, and HP ground connection. The Bleed Monitoring Computers (BMC) do not recognize if the ground cart is connected or not.

The BMC of the engines can detect overpressure and overheat and act accordingly (check FCOM for logic schematic). However, the APU logic does not check for overpressure and overheat (see below).

Having APU and ground as dual HP sources can lead to overheat and/or overpressure of the pneumatic system.

Even when starting an engine with external pneumatic power, engine bleeds should be selected off (no need letting the BCM catch an error for you).


Does go-around require more power than take-off?

It really is something watching the Buran 'takeoff' versus 'liftoff'.

The answer is no. Given the same weight it should be roughly the same power needed. That is if we are calculating it from the point of rotation for a takeoff and point of initiating a go-around.

Given the same starting conditions—weight and velocity—both aircraft will have the same kinetic energy. If the takeoff / go-around is to 2,000 feet above starting condition, then the change will be the same gain in potential energy.

If they take the same time to reach that height, then it is the same power used. (Ignoring ground effect.)

The objective of the 2 engines would be to extend the glide distance for a space reentry, say if an incorrect calculation or unforeseen event caused the space glider to come short. A corrective action would need to be applied not close to the ground, but high enough to have a meaningful effect.


A rod soft enough to not be quickly destroyed by the propeller (or to damage the propeller) would likely be too soft to apply impacts forceful enough to shatter ice along the full length of the blades.
A "baseball card" big enough to handle the full length of the blades, and also soft enough, would likely be blown aft forcefully enough to not touch the prop at all.
Frame challenge:  so-called deicing boots accomplish the same, with no risk of damage and with proven reliability, by electrically heating the blades to melt the ice.


How can I correctly calculate fuel for a Cessna 152?

The short answer is: Yes, your calculation is reasonable.

Fuel consumption values are not an exact science, they are average values and rounded in many cases or based on pilot experience. Using 24L/hr in your example for traffic patterns is the right assumption, as you will most likely remain in rich configuration. Even if you lean a bit within the pattern, you would not gain enough fuel efficiency to offset these 24L/hr.

Your 5L run-up and taxi obviously depends on the airport you are based at or use the formula at. If this value was your calculation for a smaller airfield, you might need to adapt your formula when flying to larger regional airports or airports with high-traffic, where your taxi time could be significantly longer.

Be reasonable however with topping up your values. Going from 52.6L to 60L is the equivalent of 5.3KG, which you will need to consider in your weight and balance calculation.


If an aircraft does not have an FDR, must one be installed to comply with Flight Data Monitoring requirements in EASA countries?

For 20 PAX and more, it becomes mandatory.

https://www.lepoint.fr/sport/le-piper-malibu-un-avion-delicat-22-01-2019-2287804_26.php

  Les boîtes noires sont obligatoires sur les appareils de transport public d'au moins vingt sièges.


What are some of the largest propellers post-WWII?

From Google, here are some of the largest post WWII propeller diameters:

Antonov AN-22: 20'4" (6.2 m)
Convair B-36: 19' (5.8 m)
Douglas C-133: 18' (5.5 m)
Hughes H-4 "Spruce Goose": 17'2" (5.2 m)
Boeing B-29 and B-50: 16'7" (5.1 m)
Martin Mars: 15'2" (4.6 m)
Vought Corsair: 13'4" (4.1 m)


How are taxi to and hold instructions given on an airport without taxiways to the runway end?

A is a taxiway, not the ramp. It will have stop bars and signs at the end. Here, the double solid lines are on the taxiway side and must not be crossed without clearance.

If the instruction is hold short, you hold at the end of Alpha.

NB.  An active runway is never a taxiway.  The clearances and instructions are for runways, even when backtracking.

The initial clearance will likely be:

  Taxi via Alpha, hold short runway 07.

Followed by

  Line up runway 07 via backtrack and wait.

Then finally:

  cleared for take-off runway 07

The initial clearance might combine the first 2.

  Taxi via alpha, line up runway 07 via backtrack and wait

Note that the runway designator is always the departure runway so enter 25 and backtrack would not be used.


Why does A320 Main Wheel need to be tightened 3 times during installation?

FreeMan - Commercial jet aircraft wheels are installed with a single nut on the axle, like a wheel hub on a car.
The commercial jet aircraft axle is a few inches in diameter and is hollow. The wheel bearings are tapered, and while the axle nut is being tightened the wheel is spun ih the normal direction of rotation. A higher initial torque is applied to the nut, and the pressure on the bearings helps to get the races properly seated while the bearings are rolling over them.
The nut is loosened, then the process is repeated using the torque specs specified in the manual.
One of the airlines I worked for had a policy that required that the final time the nut was tightened, it would be turned by hand. After a while, they went back to following the manufacturer's recommendations.
To recap, really tight to seat the bearings, looser for in service operation.
I hope that helps.


What are the reasons for using an instrument approach on a clear day / CAVOK?

There are actually quite a few reasons to fly an instrument approach, especially one with vertical guidance (like an ILS), even if the weather doesn't require it:

It serves as a backup to the visual approach.  There are various visual illusions that can cause a pilot to fly an approach too high or too low and monitoring the vertical guidance can help to mitigate those.
It helps to ensure that you land on the correct runway, and even at the correct airport.  (Unlike this airplane.)
ATC uses it when pilots do not have the airport or runway in sight.  This happens quite frequently at large airports where they have to line many aircraft up on final.   The last guy is a long distance from the airport so may not be able to see it but can fly the approach.
It can be useful if it is hazy or the sun is making it hard for the pilots to find the airport.
Some parallel runways are approved for simultaneous approaches (as is the case at Narita for runways 34L & 34R) so ATC will clear two airplanes for the respective ILS's.  This keeps them tracking the centerline of the approach instead of maneuvering visually where they might drift over into the way of the other airplane.
Flying the approach on the autopilot leaves more time for the pilot to focus on other things and possibly catch something that might have been missed while hand flying a visual approach.
Sometimes instrument approaches are used for noise abatement reasons.

If I had to guess about the particular approach that you mention, I would say that it is probably company SOP (Standard Operating Procedures) to fly the ILS whenever possible for the safety benefits, and that Narita allows simultaneous parallel landings to the two runways so ATC would require it as well.