Why aren't AMA certified radio-control club sites shown on aeronautical charts?

Model aircraft flying areas may be registered with a group such as AMA but there is no requirement to register these areas with the FAA. The current FAA rules expect RC pilots to stay out of airspace in use by manned aircraft, or give way to manned aircraft at all times.
It would require a lot of extra work for the FAA to register every AMA field and mark them all on charts or to enforce restricted areas around them. Also, model aircraft are not limited to AMA fields. This seems to be a reasonable compromise: the FAA lets you use the airspace as long as coordinate with nearby airports and avoid all manned aircraft.
The FAA has provided guidelines for model aircraft flying an an Advisory Circular (AC) as of January 2016:

Model aircraft operators should follow best practices including limiting operations to 400 feet above ground level (AGL).
The aircraft operates in a manner that does not interfere with, and gives way to, any manned aircraft

If you stay under 400 feet as the FAA suggests, you will not be interfering with manned aircraft, which should not fly any lower than 500 feet.
If you choose to fly above 400 feet, it is your responsibility to avoid manned aircraft. You can see them but they probably can't see your model aircraft. Stay aware of your surroundings, use a spotter if you have to.
Remember that the airspace belongs to manned aircraft, and you are only allowed to use it if you don't interfere with them.
See related question: Where is RC aircraft flying allowed in the US?


This company provides brake components for the B737,
the snubber brakes being among them:

 (Source)

They are made of what they call "AFT 200" material, which is described as:

  a phenolic treated, brass wire inserted cloth laminated under heat and pressure to a dense, strong composite. AFT 200 provides good fade and wear resistance and may be machined using standard, industry accepted practices. Its high strength makes it suitable for gear and lug driven applications.

I don't know if the snubber brakes in a KC-135 Stratotanker use this material as well, but the following picture shows where they would be installed:

 (Source)


How accurate is the inflight location information?

The route is actually quite accurate; it is derived from the navigation system of the aircraft. You can determine your departure and arrival routes pretty well from the inflight entertainment system if you are familiar with the routes on the airport you are flying.

In the image in your question you can see a slight course change East of Newfoundland. This is where the aircraft entered its oceanic track.

If the system was operating on MH370, it would have shown the course change as well.

Below you see what the IFE showed on 11 september 2001 when aircraft heading towards the USA were not allowed into US airspace after the attacks.

Source: airliners.net


Altimeter shows 100 foot drop when power is added. Is this a leak in the static system or broken altimeter and how long will the fix take?

The mechanic will do a static system leak check.  This is done by applying a sealed off suction source to the static port, then applying an inch of suction, causing the altimeter to rise a thousand feet, then holding that for one minute (I do it using a big syringe connected to the blanked off static port on my homebuilt).  The altimeter is supposed to not move more than 100 feet in 1 minute (that's the rather generous Canadian requirement - not sure of the FAA but I assume it's similar)

If there are no obvious static leaks, and the static port itself seems normal, the mech will probably swap out the altimeter and see what happens.  Or, swap out the altimeter first and then try it out.

The leak check will take about 30 minutes, and the altimeter swap-out a couple hours.  Shouldn't take more than a morning to resolve.


Can control surfaces for slow aircraft be 3D printed?

There are plenty of 3D printing methods available now with FDM being the most common. In my experience as small fixed wing UAV designer, all the 3D printing processes that are financially viable always under perform in comparison to alternatives. I can tell you the main issues I have encountered leaving the printing defects out:

additive manufacturing doesn't lend itself well to mass production.
It is too heavy for a core material.
melts under heat, Fire hazard and safety issues.
FDM prints are susceptible to fatigue especially when stress is transverse to the layers
for commercial use , the end customer doesn't like 3d printed parts on his aircraft. simple as that
machined metal parts are always stronger and cheaper than metal 3D printed parts.

However, it has some major benefits but mostly as a prototyping method. You can test the fits and physical size rather cheaply. I use it sometimes as a mold pattern for small parts. Also, 3D printing wings is not as common as you would think in RC world.
TLDR; with current technology, 3D printing is not suitable for stress critical components.


What kind of materials is being used for Fighter jets glass shields?

Today, the canopy is a multi-layer structure. In case of the F-16, it consists of three layers:

The innermost layer is 0.5 inch thick polycarbonate and drape-molded into the compound curvature shape.
The center layer is 0.05 inch polyurethane to bond the inner to the outer layer.
The outer layer is a 0.125 inch layer of acrylic (PMMA).

The canopy is bolted to a metal frame for assembly. Some canopy also use explosive cord on the outer layer to fracture the material shortly before the ejection seat fires.

F-16 canopy (picture source)

For less fast aircraft, a single layer of acrylic is sufficient. Funnily, the company which produces most of those canopies doesn't even have a page in Wikipedia. They use flat PMMA sheets and drape-mold them over a mandrel. The secret of their process is the grease they put on the mandrel so the acrylic flows easily into shape.


What are these antenna-like protrusions for on an airliner?

They are the various communication and navigation antennas of the aircraft. This figure shows the location of antennas in A320, the type of aircraft in picture.

Source: pprune.org

Some antenna (the ones with *) are optional and the installation varies with customer. The communication antenna location in A320 can be seen in this image.

Image from airbus training course from airbus.altervista.org

And the navigation antenna location in this one:

Image from airbus training course from airbus.altervista.org

The dome (2 in the picture) is the radome for the wi-fi system introduced by Jetblue, dubbed Fly-Fi.

Source: nycaviation.com

So,

1,3,4 - VHF
2 - Wifi
6 - ELT


Why do new helicopters have rotor blades with swept tip?

Helicopter rotor design is, among many other things, a balancing act of retreating blade stall and transonic effects on the advancing blade.
Helicopter blade tip devices usually serve to reduce transonic effects on the advancing blade. The Ka-50's blade tip is rather simple (only swept) as the coaxial design is affected less from these transonic effects, as they happen on both sides. For the same reason, retreating blade stall is also a lesser problem, so the designer can get away with a slower blade tip speed.
Helicopters with a single main rotor don't have this luxury, so many of them have complex blade tip devices with sweep, larger chord and sometimes different airfoils. I believe a good example is the Westland (now merged, AgustaWestland) Lynx.

Blade leading edge is top of picture. Sweep, increased chord and droop on end are evident.
For my Bachelors thesis, I was looking for blade tips with the highest drag divergence Mach number, the Lynx blade tip's was M 0,91. I believe this is an important reason why the Lynx is the fastest conventional helicopter.


Per the German Meteorological Service, the + means a ceiling 20,000 feet or higher.

  BLU: visibility>=8000m, ceiling 2500 - <20000 ft

  BLU+: visibility>=8000m, ceiling >=20000 ft


Different kinds of Software

We need to distinguish between several categories of software.

Field-loadable software (FLS) is, loosely defined, any software which can be reconfigured, updated, or uploaded by technicians and manufacturers, like the avionics software.
Aeronautical databases are not categorized as field-loadable software and are treated separately in regulations. These aeronautical databases may be a terrain database, a navigation database, an obstacle database, or an airport map database.
Factory loaded software, which is assumed not to change during without replacing the device it's on.  To change factory-loaded software you often have to break a seal and flash the memory.  It may also be on read-only memory like an EEPROM.

Thanks to advances in FLS practices, field-loadable software is being used in many places where factory-loaded software had been used previously and frequent software updates are becoming common on most systems. Software on virtually any part can be field-loadable if it follows safety and integrity measures.

Aeronautical databases are treated differently in part due to the difference in update frequency. An aeronautical database must change frequently (often more than once a month), while avionics updates are less frequent and may be less than once a year (especially because the entire aircraft configuration, software included, must be certified).

What steps are taken to update software?

A patent by Airbus explains the process excellently, even with diagrams in French:

  The first step is managed by the manufacturer of the aircraft. The latter decides upon a required modification for the aircraft it has constructed. It develops the modification for the solution found and certifies it with the certification authorities. The manufacturer thus shows that the new configuration proposed is compatible with the environment and with the configuration of the aircraft for which the modification is destined.
  Once the solution has been developed and validated, the manufacturer prepares a pack, referred to as service bulletin, containing a description of the operations to conduct to perform the modification of the aircraft and also a physical element containing the software to change and furthermore containing corresponding documentation. The physical element containing the software depends on the size of the software and it may for example be a USB key (USB standing for “Universal Serial Bus”), a CD/DVD, etc. This pack is delivered physically to the company concerned that operates the aircraft. This delivery may also be performed electronically.

  The second step is carried out under the responsibility of the operator of the aircraft, for example an airline company, or, when the aircraft is under heavy maintenance under the responsibility of the maintenance organization authorized for that. Similarly, this step may be performed by an authorized MRO (standing for Maintenance Repair Organization) when the aircraft is transformed for a change of operator. This is typically of the case for an aircraft hire company.
  The operator receives the service bulletin and transfers it to a technical center (FIG. 1) in order for the operator to allocate and verify the compatibility of the service bulletin received with the environment of the aircraft of its fleet. Once the verifications have been performed and the service bulletin validated, a work request is sent to the maintenance management department of the operator's fleet. That department then defines the times (stopover, heavy maintenance visit, etc.) at which the aircraft may undergo that update and provides the workshop with the software element to install on the aircraft (USB key, DVD, etc.).

  A maintenance workshop of the airline company or of a maintenance repair organization performs the requested task and downloads the software which is in the DVD or USB key (or other medium). The action is recorded and the configuration repository of the aircraft is updated. Of course, the technical center (and possibly other departments concerned) is kept informed of the upgrade which has just been carried out.

Navigational database updates were traditionally updated using a similar process according to this Honeywell patent:

  ... the information contained in the navigation database changes on a very frequent basis as new navigation aids are created, old navigation aids are retired, airports add or retire runways, or the like. Accordingly, government agencies such as the United States Federal Aviation Administration (FAA) typically require that aircraft update navigation databases on a regular basis, such as every twenty-eight days. Other components (such as global positioning systems (GPS)) may also make use of periodic data upgrades.

  Conventional techniques of updating databases have been cumbersome and time consuming. Typically, a customer (such as an airline) obtains a diskette containing the upgrade for a particular aircraft type from a database or component vendor. The customer then duplicates the diskette and distributes copied diskettes to service technicians, who then go to individual aircraft and manually load the data update using a specialized data loader...

See also https://www.google.com/patents/US20030208579 for an example of how in-flight entertainment systems are traditionally updated.

What media is used?

A variety of media has been used over time since storage media changes quickly. Physical media like CD's are quickly being replaced by high integrity network updates due to the cost benefits involved.

A patent for a "Method for controlling customer-implemented data updates" explains how this process was done historically:

  Originally, airline maintenance personnel upgraded flight management
  computers by using an ARINC standard 603 portable tape upload device,
  but such tape loaders were clumsy and slow. Manufacturers then
  progressed to data loading computers that were based on ARINC standard
  615 (Data Loader standard), which is in essence a software protocol
  layered onto an ARINC standard 429 data bus. ARINC 615 data loaders
  abandoned the tape format of ARINC 603 in favor of a 3.5-inch floppy
  diskette medium for transferring data and software... The
  software or data for these updates has grown increasingly more complex
  as the systems in aircraft provide more functionality to the cockpit
  crew and traffic control.

In more recent history, "The media used to load FLS changes with time. In the early 1990's, 3.5 inch diskettes were used.  For example, the original Boeing 777 carried around binders full of floppy disks.  The technology has moved on to compact disks (Cds), digital video disks (DVD's) thumb drives, mass storage devices, and even local area networks (LANs)" source

Another patent discusses in detail the way that software can be loaded over LAN.  The image below is from the patent.  The principles are much the same:

The software must be part of a certified aircraft configuration
Aircraft in the fleet are checked over the network to see if their configuration is out of date or incorrect
Aircraft are updated to a new configuration when and only when the operator initiates the update
A reliable integrity check like a CRC is in place to make sure the update over LAN was successful

What safety and integrity measures are taken?

Fun fact: Field loadable software is considered a part, and therefore the configuration management that applies to parts also applies to software updates.  The updated software must be certified for the aircraft configuration it's on, must have a part number which can be verified, and must appear on the bill of materials for the new aircraft.  Sometimes an entire device will have a new part number when its software is updated, or sometimes the software has a separate part number that's updated while the hardware retains its own part number. Any modifications to the software must go through a change-impact analysis and recertification.

The field loadable software must be certified for the device and aircraft it's being loaded on and there must be checks on the software loading process, the software itself, the software part  number.  DO-178C specifically specifies that:

there must be protection from inadvertent loading (which also means that unlike Windows, it won't force you to update at the worst
possible time)
there must be detection of failed, partial, or corrupted loads
you must be able to reliably determine that the currently loaded software and all its files are correct (for example, by using a CRC)
if a display mechanism is used to display the software load, the display must be accurate and reliable

Integrity checks must have a level of reliability, similar to other reliability check in aircraft.  This often means that the software loading must have a 10^-9 chance of corrupting software or incorrectly indicating the software load is correct.  You can instead qualify the tool used to load the software, but this is less common than showing that the integrity checks are reliable.

Chain of Trust for Aeronatuical Databases

For aeronautical databases, safety levels and error checking are also seriously considered.  Each particpant in aeronautical database creation and transmission must have a compliance plan, configuration management, error checking, a method to ensure unauthorized changes don't occur, and quality management.  As outlined in AC 20-153, The FAA will provide a Letter of Acceptance (LOA) to each particpant in this process indicating their compliance with regulations like DO-200A.  Aeronautical data must meet various standards as applicable like ARINC 424 and DO-291B, but a discussion of those is out of scope of the question.

For more information:

Chapter 5 of FAA Order 8110.49 specifically addresses approval of field-loadable software.  RTCA's DO-200A is the standard for preparing and transmitting Aeronatuical databases from a regulated data provider to the operator of the aircraft.  See also FAA AC 20-153 for certifying compliance and granting letters of Acceptance to DO-200A.
I have heavily referenced "Developing Safety-Critical Software" by Leanna Rierson.  I suggest you reference this or another book.

Disclaimer:  I am not a DER or engineer for the data loading process and so this information is for reference only. For technical work please consult the source documents and a DER instead of relying on this information.

Updating A380 navigation using flash drives


What is the best method for an emergency takeoff?

Near as I know there are no emergency takeoff procedures and for good reason:  if you do have an emergency, stay on the ground. Period.  As for emergencies which happen during a takeoff roll, this one really isn't covered among them as there really is no emergency regiment to get airborne.  The KLM captain in the Tenerife accident made a series of judgement errors and failure to follow ATC instructions combined with bad weather and a crowded airport which contributed to the accident.  Once he was rolling, the best he could do was just hope the plane would reach Vr and climb over the PanAm jet, which didn't happen.  He panicked at the end with the tail strike, only making things worse.  But at that point he had painted himself into a corner with no escape.


Both, and it depends.  When a Hot Section Inspection is done, they are looking for mostly blade erosion beyond dimensional limits, and cracks.  Some cracks are allowed if the OEM's engineering determines they are benign (sometimes cracks form which fully relieve the stress that initiated them and the crack stops propagating - such cracks can be left alone, and the engine OEM will have clearly defined crack allowances and limits).

Erosion is mostly a function of how dirty the atmosphere is.  An engine running in the high Arctic that sees very little dust (outdoor dust close to the ground is mostly silica particles - sand paper without the paper) may run a very long time before significant erosion and the hot section might only have to be rebuilt due to burner can or blade cracking from operating cycles.

An engine running in the Middle East may only run half the normal TBO before blade erosion forces the engine off, made worse if an operator avoids using flex thrust to minimize engine demands on takeoff.

Then, some engines are more susceptible to erosion than others, depending on the compressor inlet design.  Turbofans with a stronger ram effect (good for overall efficiency and for windmilling after a flame out) suffer more than those with less.


What is the ICAO equivalent of /G in a flight plan?

I have a GNS-530W, which is identical to your unit except with a bigger screen and I file ICAO with a G, B, and S, which are GNSS/GPS, LPV, AND VOR/ILS, respectively, to indicate the equipment I have on board. Technically just the G would be sufficient but I list all I am capable of to assist ATC in routing me most effectively or in the event of an emergency.

This would be entered on the form as "G, B, S"

Here is an excellent article explaining the new fields and codes for filing ICAO as the FAA domestic flight plan form comes to an end soon:
Filing ICAO Flight Plans in ForeFlight


Is it possible to drop a payload via anchored parachute?

I'm trying to drop a payload via parachute with some accuracy.

Cut a hole in the middle of the parachute, make its edge smooth and install a pipe through the center of the box that contains the payload. Run the line through the pipe and parachute and let the payload fall from the balloon. I believe the trick will work for small parachutes able to deliver up to 10 kg to the ground.


A good source of public information is the aircraft characteristics document that the manufacturers typically publish for each model, including the A380.

A scale planform drawing can be found on page 310 of the PDF, subject 8-0-0. Based on this drawing, the rough size of the ailerons can be estimated.

The aileron is divided into three sections which move independently (see Why do some aircraft have multiple ailerons per wing?). The outboard section is about 4m (13 ft) long, the middle section is about 3m (10 ft) long, and the inboard section is about 2m (6.5 ft) long. In total they are about 9m (29.5 ft) long.

Derived from Airbus document:

Ailerons viewed from cabin:

Image source (other question)


Why don't helicopter blades look like other propellers?

Helicopter blades need to be long and thin. The diameter of the rotor disc determines the efficiency of the rotor at low speeds and can be compared to the wing span in fixed-wing airplanes. The rotation creates strong centrifugal loads at the blade roots which grow with the square of the tip radius at a given rotation speed, so they cannot be tapered much. Adding chord to the middle of the blade would increase its area and add more friction drag, increasing the torque needed to keep the rotor spinning. If the helicopter is only designed for hover, the blade tips could be tapered, but the added complications of forward flight make a rectangular blade the better choice.

In forward flight, the speeds due to the blade's rotation and the flight speed add up, increasing local airspeed at the advancing blade and reducing it at the receding blade. Since the center of lift is trimmed to be at the rotor hub using the swash plate, the advancing blade has a smaller angle of attack and the receding blade a higher angle of attack. On the receding blade at high flight speed, the root will be in reverse flow since here the rotation speed will not be high enough to compensate for the flight speed. Dynamic pressure is around zero at the middle radius, and only the tip area sees sufficient dynamic pressure to create the lift which is demanded from the blade. Reducing this tip area would reduce the lift which can be produced there, so designers kept the blade chord constant.

Two effects limit the maximum forward speed: The remaining dynamic pressure at the blade tip of the receding blade, and the maximum Mach number at the advancing blade's tip. In order to increase this maximum Mach number, modern rotor tips are swept, but simple sweep will lead to torsion moments which will twist the blade. The pitching moment along the blade needs to be finely balanced so no torsion loads result. To achieve this, helicopter blade airfoils are either symmetric or reflex, and the tip is first swept forward and then backward, so the resulting lift acts exactly at the elastic axis of the blade. See the picture of such a blade tip below. The small trim tab you can see at the trailing edge is used for fine-tuning the pitching moment of the blade.

Eurocopter Blue Edge rotor blade (picture source)

I would not be surprised if an optimized rotor shape has non-rectangular blades, but my impression is that the gains of optimization are small, especially with the wide spread of operation conditions of all rotor blade sections. The rectangular blade is easy to manufacture and good enough for most cases. However, I have not designed a rotor myself and do not know enough about the details to be more specific.


Does ducted fan require more engine torque than unducted-fan,at same RPM?

Two identical fans […]
I think ducted fan require more torque for same RPM

Yes, a little more. The shroud prevents the air flowing directly around the tips, allowing them to produce more thrust. And this extra thrust comes with induced power.

but in theory wall to wall airfoil must has lower drag than 3D wing at same speed and same AoA.

No, it doesn't. The comparison is always made for the same lift, never the same AoA.
For the same AoA the drag should be higher for the same reason as above.


How do airplanes get stacked in a holding pattern?

ATC has many tools "in their belt" to keep traffic separated. When things back up, it can get crowded. Emergencies and weather regularly cause disruptions and ATC handles them according to the circumstances.

To illustrate some possibilities, I will use Seattle as an example here. You can find the airport information here.

Most aircraft coming into the area will be commercial flights on IFR flight plans, and they will follow a Standard Terminal Arrival (STAR) into Seattle. You can find this seciton towards the bottom of the AirNav page. There are different STARs depending on the direction from which the flight is arriving. Each STAR will include published holding patterns.

Listed here is the direction of arrival, the name of the STAR, and the holding fixes:

East - EPHRATA - FLAAK, EPHRATA, ODESS
East - GLASR - LOSTT, TEMPL, JAKSN
Southeast - CHINS - SUNED, BRUKK
South - OLYMPIA - BTG, OLYMPIA
Southwest - HAWKZ - BTG, HAWKZ
Northwest - JAWBN - JAWBN
Northwest - MARNR - MARNR

As you can see, there are 11 different holding fixes across the seven STARs. If you have one aircraft from each direction, they can each hold at the fix according to their STAR. The busiest STARs have multiple holding fixes that may be used. Aircraft may also be stacked on the same hold at different altitudes. You can read some FAA information about holds here.

Aircraft may also choose to divert. Depending on how much fuel they have and how the weather/emergency is playing out, they may not want to hold indefinitely on the GLASR arrival at LOSTT. Generally ATC will not ask for a diversion unless absolutely necessary. Among others, Portland, Vancouver, and Spokane are all fairly close to where the aircraft may be holding and could be viable alternates.


What's the difference between a Terminal Control Area and a Control Zone?

A Control Zone is the small (and usually circular) surface area around the airport that is handled by the airport's control tower. At smaller airports (but still large enough to have a tower), this is all they have.

A Terminal Control Area is a large and typically complex area above one or more Control Zones to manage large flows of fast traffic (i.e. airliners) moving in both directions through the congested area between the Control Zone(s) and the en route environment far above.

Note that while Canada (and the US, though it uses very different terminology) often uses the same class of airspace for the TCA and CZ, that isn't required, and there may even be several CZs with different classes under one TCA.


How is Reynolds Number derived and used?

You can derive the Reynolds number by non-dimensionalization of the Navier-Stokes momentum equation: Wiki link

The choice of reference length and velocity is somewhat arbitrary: usually they are chosen so that they represent "fundamental" dimensions of the study case, e.g.:

For a cylinder in a flow: freestream velocity and cylinder diameter
For a pipe: mean velocity and inner diameter
For a flat plate: freestream velocity and distance from leading edge

In the end of the day, it is a matter of conventions, but what you choose must be physically relevant (e.g. you cannot choose the plate thickness) in a way that, increasing either of them, you go from laminar to turbulent flow. Once the choice of the above pair (length, velocity) is standardized, you can define a critical Reynolds number, which marks the boundary from laminar to turbulent flow (actually, a range of it because of the complex behaviour of fluids during laminar-turbulent transition).


Is the descent performance of the PMDG 737-800 accurate?

You haven't provided everything possible to really ascertain the issue noted, but based on what you have I've noticed the following things:

You'll find most 737s at 240-250 KIAS passing through 10000 feet, rather than the 220 knots that you were going at (while 220 KIAS is above minimum clean speed at normal landing weights, it's still slower than most)
Being heavy actually makes minimum drag and max L/D speeds higher, which means that for the same speed, you'll actually descend at less of a gradient than if you were lighter
The Boeing 737-800W has a idle descent ratio of about 1:20, which means that at 250 knots you're only going to be descending about 1200fpm -- the 737-800 (especially with winglets) is a very slick bird.

For your reference, you can see the distances required for an idle descent (.78/280/250), plus allowances for a straight-in approach:

|=====================================================|
|          |       |      |       DISTANCE (NM)       |
| PRESSURE |       |      |---------------------------|
| ALTITUDE | TIME  | FUEL |  LANDING WEIGHT (1000 KG) |
|   (FT)   | (MIN) | (KG) |  40  |  50  |  60  |  70  |
|----------|-------|------|------|------|------|------|
|   41000  |   27  |  340 |  102 |  119 | 133  |  142 |
|   39000  |   26  |  340 |   97 |  114 | 127  |  136 |
|   37000  |   25  |  330 |   92 |  108 | 121  |  130 |
|   35000  |   24  |  330 |   88 |  103 | 116  |  125 |
|   33000  |   24  |  320 |   84 |   99 | 111  |  120 |
|   31000  |   23  |  320 |   80 |   94 | 105  |  113 |
|   29000  |   22  |  310 |   75 |   88 |  98  |  106 |
|   27000  |   21  |  300 |   70 |   82 |  92  |   99 |
|   25000  |   20  |  300 |   66 |   77 |  86  |   92 |
|   23000  |   19  |  290 |   61 |   71 |  79  |   85 |
|   21000  |   18  |  280 |   57 |   66 |  73  |   78 |
|   19000  |   17  |  270 |   52 |   61 |  67  |   72 |
|   17000  |   15  |  250 |   48 |   55 |  61  |   65 |
|   15000  |   14  |  240 |   44 |   50 |  55  |   58 |
|   10000  |   11  |  200 |   30 |   34 |  37  |   39 |
|    5000  |    7  |  150 |   18 |   19 |  20  |   21 |
|    1500  |    4  |  110 |    9 |    9 |   9  |    9 |
|=====================================================|


From which ATC station is push-back clearance requested?

At controlled aerodromes, the aerodrome control tower is responsible for separating aircraft on the maneuvering area (from other aircraft, and from obstacles, vehicles etc.). If a pushback is done onto a taxiway which is a part of the maneuvering area, the aerodrome control tower must approve this first. At large aerodromes, there are different tower working positions, operating on different frequencies and with different callsigns. So the "which exact ATC station" question really varies from airport to airport. You might talk to "xx tower", "xx ground" or something else entirely.

Note that at many airports, the gate area (apron) is NOT a part of the maneuvering area. Technically speaking, ATC is not responsible for separating aircraft outside of the maneuvering area. Instead, pilots, tug drivers, vehicles and other persons on the apron follow different priority rules when a pushback is required (traffic laws normally state that vehicles shall yield to aircraft; the rules of the air have rules regarding aircraft right-of-way).  However, some major airports have designated positions for coordinating this effort, which - from the pilot perspective - looks just like ATC. They operate on a VHF frequency, and typical callsigns are "xx apron" or "xx ramp". Note, however, that such stations do NOT provide air traffic control - technically, they provide advisory service, and they are not responsible if a collision occurs, because ATC separation is not provided outside the maneuvering area. Persons staffing such positions generally do not have to be fully qualified air traffic controllers (this will vary from country to country), and are sometimes employed directly by the airport, instead of an air navigation service provider.

In summary: if the pushback occurs on the maneuvering area, the aerodrome control tower has to approve it. If not, no ATC approval is required, but there might still be other stations coordinating pushback.


How to demonstrate that an elliptical circulation distribution can be induced by an elliptical chord distribution?

First, let's transform the coordinates to polar coordinates for simplicity by introducing a variable $\theta$ such that:
$$z=-s\cos{\theta}$$
In this coordinate, the chord distribution is then:
$$c(\theta)=c_C\sin{\theta}$$
Let's write the unknown lift distribution of the bound vortex as a Fourier sine series, again in the $\theta$ coordinate:
$$\Gamma(\theta) = \sum_{n=1}^{\infty}A_n\sin{n\theta}$$
Through Biot-Savart, the induced AOA can be computed from the trailing vortices, such that:
$$\alpha_i(z) = \frac{1}{4\pi V_\infty}\int_{-s}^{s}{\frac{(d\Gamma/d\zeta)}{z-\zeta}d\zeta} = \frac{1}{4\pi V_\infty}\int_{0}^{\pi}{\frac{\sum_{n=1}^{\infty}{nA_n\cos{n\theta_0}}}{\cos{\theta_0}-\cos{\theta}}d\theta_0} = \frac{1}{4V_\infty}\sum_{n=1}^{\infty}{nA_n\frac{\sin{n\theta}}{\sin{\theta}}}$$
Now collecting everything together and put into your original equation, we have:
$$\Gamma(\theta) = \frac{1}{2}a_{2D}V_{\infty}c_C\sin{\theta} \left[ \alpha - \beta - \frac{1}{4V_\infty}\sum_{n=1}^{\infty}{nA_n\frac{\sin{n\theta}}{\sin{\theta}}} \right] = \sum_{n=1}^{\infty}A_n\sin{n\theta}$$
The key, at this point, is to realize that each $\frac{\sin{n\theta}}{\sin{\theta}}$ is linearly independent to the others, so in order for the other terms to satisfy the above relation for all $\theta$, they must be simultaneously zero. That is,
$$A_n = \begin{cases}
      A_1 & n=1\\
      0 & n>1\\
    \end{cases}$$
So now the circulation and chord distributions have the same form, which are elliptical.


While @Peter Kämpf 's answer is great and sufficient to answer the question, I would like to add a clarification (which should be a posted as a comment, but is too long for this format).

In the image in the question, there are visible streams of condensed water vapor from the atmosphere. These streams are only present at the blade tips. The question seems to assume that these streams depict the wake from the propellers. They don't, or more accurately there are only a very small part of the wake volume.

1. Images of tip vortices from different devices

1a, tip vortex from a propeller

Source

Condensed water forms because the change of pressure is adiabatic, in simple terms it occurs with little exchange of heat with the neighboring regions. It occurs first where the pressure difference is large and the transition quick. (By the way, note the 8 rockets used to assist for takeoff.)

1b, tip vortex from a wing

Source

1c: tip vortex from a rotor

Source

There is not doubt the rotors spin in opposite direction.

1d, tip vortex from a wind turbine

Source

Notice: Actually after looking at oddities on this image (the direction of the wind), I realized that this is an experimental turbine used by the US DoE and the NREL to study winds. The white stream is actually smoke released from the blade. Probes are visible on the leading edge to measure speed at different locations of the blade. I keep the image as it's a good one.

2. Full wake turbulence

Contrary to the previous images, the ones below show the whole turbulence created by the same airfoils. While the tip vortices are materialized by condensed water vapor created by a transition from high to low pressure at the tip of the devices, the whole wake is visible only if air is not clear.

2a, turbulence from a propeller

Source
Principle (no photo found, do you have one?)

2b, turbulence from a wing

Source

2c: turbulence from a rotor

Source

2d, turbulence from a wind turbine

Source

3. Images where both effects are combined

Note that regardless of whether they are visible or not, both the tip vortices and full wake always exist. Their visibility greatly depends, like contrails, on the air moisture and temperature.

As explained by @Peter, the energy of the tip vortices is diluted in the energy of the actual wake turbulence:

Source

Source: What causes a plane's wing tips to leave a small white vapor trail?

4. Complexity of the wake

Wake from a wind turbine, mixing all sources of turbulence:

Source

The tip vortex is initially a very small part of the wake, created by the high pressure air escaping from the low side of the wing. The whole wake volume grows in length and diameter as the airfoil moves. The vertex diameter grows, until there is no more energy left and air stops moving (see images in §3):

Source

Source

See this question for details: How does an aircraft form wake turbulence?


For large jets, what is the primary means of slowing down after landing?

The brakes are much more effective than anything else, at least for the jet I have experience in (EMB-145).

Our landing performance data typically assumes full braking application, spoilers deployed and no reverse thrust.  The airplane will most certainly stop without using reverse thrust, just not as fast.  I never tried not using the brakes, and if I were to I would want a light airplane and a very long runway.

As Lnafziger pointed out in the comments, the brakes are part of redundant systems so that they are always available.  In the EMB-145, the brakes were serviced by two independent* hydraulic systems. The inboard brakes were on one system while the outboards were on the other for a total of four wheels each with big carbon fiber brakes.

To address the comments on slick runways, assuming braking action allows an attempt to land in the first place, you have to be careful. With reverse thrust alone you may not be able to maintain the runway centerline and directional control may become difficult through uneven deployment of the reversers and other factors.  In this scenario the spoilers are helpful to increase traction and brake effectiveness.  In short, if the runway is slick then the only way I'm attempting a no-wheel-brake landing is after declaring an emergency.

Finally, to address the question in the title, the wheel brakes are always the primary means of slowing the airplane.

*You could transfer fluid between our systems through the parking brake.


How could a light or buzzer on the ground be triggered from an aircraft?

People on the ground should have a radio tuned to listen to the local frequency. Then the pilot can simply radio a call to notify the people on ground (and any other planes that may be nearby) about the skydivers.

Having this radio also means that during emergency (like a jumper getting caught on the plane) there can be coordination between pilot and ground crew.


How are these parameters derived from readings of sensors in an aircraft: angle of attack, slip angle, and airspeed?

They use test flights.

They attach more instruments to the plane and move them outside the influence of the planes own turbulence.

From the known good values of these test instruments they can calibrate the actual instruments.


How can I decode Lycoming engine number?

I got the following information for this website:

Also if you scroll down here you can see the model numbers that you talk about in your question.

The last character seems to be an indication of the variant of the engine as shown in the document.  The D indicates Dual Magnetos and the 2 or 3 seems to indicate some type of counterweight application.


Could someone please explain why the A320 doesn’t have an anti ice system for its vertical and horizontal stabilisers?

On PPrune I found:

  The aircraft has been designed to account for that. (Simplistically,
  the tail is over-sized to compensate for reduced effectiveness when
  ice forms; it's easier/cheaper/simpler to make the tail a bit bigger
  and take a weight penalty than to install a whole extra anti-icing
  system on the tail, which is why that's the typical approach for
  higher speed aircraft)

To me this makes sense, as the weight penalty for making the tail a bit larger is not as big as the weight penalty for making the wing a bit larger.

Another thing that is different between wings and empennage is ice build up on the wing near the engine could suddenly let go and end up in the engine and cause damage. To prevent the ice buildup, anti icing is used. On the empennage this is no issue.


Is there a way to obtain real-time METAR data?

You might know this already, but if you want to get an AWOS/ASOS report minute by minute, you can call most of the automated sites. In the US the phone number is listed in the A/FD.


What is the difference between an aileron and a flap?

An Aileron is used to control the roll of an aircraft. Ailerons are found on the trailing edge of the wing, typically closer to the wing tip.
Ailerons will move in opposite directions to each other, as one goes up, the other goes down.

Flaps are used to increase the amount of lift that a wing produces by increasing the camber and surface area of the wing. Typically they are located near the root of the wing. Flaps on each wing are moved together, both extend and retract at the same rate.

Flaps are generally more complex depending on type. The basic flaps will just pivot down from the lower edge of the wing. Modern airliners have a fowler flap which both pivots down and extends back from the lower edge of the wing.


As a general rule, must the cg of a tandem ultralight be greater than 25% mean aerodynamic chord?

you want the cg always behind the Cp (25% MAC) of the wing, but in front of the plane's neutral point, as you want the tail to provide an offsetting tail up force

Yes, that is correct. The cg should be between the forward wing's quarter point and the common neutral point (NP) of both wings. However, if you want some agility when maneuvering the plane, it should be much closer to the neutral point. If both wings are of equal size, you definitely want the rear wing to contribute some lift. Since it flies in the downwash of the forward wing, it will see a smaller change in effective angle of attack and have a smaller lift curve slope, which already supplies some stall margin by helping to let the forward wing stall first. By shifting the cg a bit forward of the NP (10% to 25% of MAC should be sufficient), you will reduce lift on the rear wing further and increase stability.

  I understand the centre of pressure of a classic wing is at it's quarter point.

Only if the wing has a symmetric or reflex airfoil. With regular cambered airfoils the cp is further aft and moves forward to the quarter point with increasing angle of attack.


Why only the outboard ("low speed") aileron drops when there is no hydraulic pressure on the 747-8?

The Boeing 747-8 (unlike the 777) is not a full fly-by-wire aircraft, but some fly-by-wire controls have been added to the original 747 design. The inboard ailerons are mechanically connected to the flight controls, while the outboard ailerons are not. This allows them to droop without hydraulic power.

From the Boeing 747-8 FCOM (9.20.6 Flight Controls - System Description):

  Roll Control

  Inboard ailerons are mechanically controlled and hydraulically powered. Outboard ailerons and all spoilers are electronically controlled and hydraulically powered.

  Aileron and Spoiler Roll Control

  Rotating either control wheel positions ailerons and spoilers. Above approximately 258 knots/.53 Mach, the outboard ailerons are commanded to the neutral position to prevent overcontrolling. The outboard ailerons become operational at lower airspeeds. Inboard aileron deflection is limited when flaps are extended beyond 10.

  To improve takeoff performance and reduce noise, the outboard aileron is deflected down for flap detent positions 10 and 20. The downward deflection is removed if the angle of attack is above stick shaker. The inboard aileron is deflected down when the flaps are selected to 10 or greater.

  All spoiler panels operate with the ailerons. Spoiler panels are deflected up or down based on Speedbrake lever and control wheel inputs.

The following image from modernairliners.com shows all new features of the 747-8 wing including the Aileron droop.


I’ve chatted with a few F-14 pilots who are members of the Tomcat Association, aviation museum curators, as well as former NFWS Topgun instructor Dave “Bio” Baranak about the possibility of getting one or two F-14 airframes flying again.  The depressing conclusion we have all come to is that it is almost impossible for this to happen.  Multiple F-14 pilots, RIOs and maintainers have approached the DOD about doing so, to no avail.
Virtually all Tomcats which did not get donated to museums were cut up and melted down into beer cans, more or less.  The Navy destroyed nearly all of its Tomcat fleet to prevent spare parts from winding up in Iran, the last known Tomcat operator.  As of 2018, the DoD did maintain at least 11 flyable F-14 airframes in long term storage at AMARC and they are not parting with them.  Period.  The exact reason the DOD keeps these aircraft is unclear, though I suspect they are retained for limited purposes such as RedAir aggressor aircraft, flight test and research, or similar role that the type is deemed suitable for.  F-14s which were donated to museums or for public display as “gate guards” still remain the property of the DoD and the airframes have been mutilated to permanently prevent them from carrying flight loads.
The only other potential source of flyable Tomcats remains Iran and it’s believed that all or nearly all are out of commission due to lack of spare parts.  If somebody could purchase an F-14 airframe from Iran, then take it back to the states, it might be possible. However this would almost certainly be seized and confiscated by customs.
And even if you could get the aircraft back into the United States legally, plus find the enormous funding required for this enterprise, you’re still faced with the prospect of finding spare parts for it.  It will be very difficult to get anything from the manufacturer i.e. Northrop Grumman as the assembly lines have long since closed, there are ITAR and national security restrictions, and all existing spare parts, aside from those needed for the last AMARC F-14s, have been destroyed.
It’s a great dream, but it looks like if you ever want to see an F-14 fly again, the closest you will get is watching a DVD of Top Gun or Final Countdown.


Can small planes see lights on the ground?

Yes we can see lights on the ground from small planes, but your extra lights do not help approaching aircraft. If anything they may serve to disorient pilots. In low visibility situations, provided the pilot is properly rated and the aircraft is properly equipped they may be flying IFR. Under these types of operations when popping out of the clouds we may be looking for runway lighting. Other lights on the ground can (and have been) confused for runway lights in the past.


Is it possible to hand start modern planes?

You sure can!

In reality the engines in modern prop planes are not all that different (in some cases even identical) to the engines of the hand crank days. The reason many older planes were hand crank was simply to save the weight toll of a starter motor and battery to drive the system. Some older aircraft have no active electronics (the piper cub comes to mind). Remember the engines magnetos drive the spark for the ignition system unlike in a car where the spark is driven by the electronic system. As long as proper precaution is taken its more than possible. The FAA even explicitly discusses it in their airplane flying handbook (p 2-13)

  A spinning propeller can be lethal should it strike someone.
  Historically, when aircraft lacked electrical systems, it was
  necessary to “hand prop” an aircraft for starting. Hand propping an
  aircraft is a hazardous procedure when done perfectly. The
  consequences of not mitigating the hazards associated with hand
  propping can lead to serious injury, fatalities, and runaway
  airplanes. All alternatives must be considered prior to hand propping
  an aircraft and, when a decision is made to do so, the procedure must
  be carried out only by competent persons who have been trained to
  accomplish the procedure, understand how to mitigate the hazards, and
  take all the necessary precautions.

They also provide a pretty clear checklist on how to do it.

  The procedure and commands for hand propping are:

  • Person out front
  says, “GAS ON, SWITCH OFF, THROTTLE CLOSED, BRAKES SET.” 2-14

  • Pilot seat occupant, after making sure the fuel is ON, mixture is RICH,
  magneto switch is OFF, throttle is CLOSED, and brakes are SET, says,
  “GAS ON, SWITCH OFF, THROTTLE CLOSED, BRAKES SET.”

  • Person out front, after pulling the propeller through to prime the engine says, “BRAKES
  AND CONTACT.”

  • Pilot seat occupant checks the brakes SET and turns
  the magnetos switch ON, then says, “BRAKES AND CONTACT.”

As far as i know, you can not hand start a turbo prop (which some GA planes have) due to the higher RPM needed for start.


In constant speed propeller, if i increase RPM lever from 2300 to 2500, will the Blade AOA decrease?

When you adjust a constant speed propeller to a higher rpm, this will be done by making the propeller blade AoA smaller.
Contrary to your question though, manifold pressure and power output will not remain constant unless you adjust the throttle. Neither will your airspeed, not surprisingly.
Exact effect will depend on the engine, but basically power is torque x rpm, so for a constant throttle position, increase in rpm will increase power output unless we are near max rpm.
See What is the relation between manifold pressure, RPM, and power, in a constant speed prop? for reference.


What are the visual differences between the ATR42 and the ATR72?

By Julien.scavini (Own work) [CC BY-SA 3.0], via Wikimedia Commons

The ATR72 is quite a bit longer than the ATR42, and has several more windows to allow for more passengers.

According to Wikipedia:

  The ATR 72 was developed from the ATR 42 in order to increase the maximum seating capacity (from 48 to 78) by stretching the fuselage by 4.5 metres (15 ft), increasing the wingspan, adding more powerful engines, and increasing fuel capacity by approximately 10 percent.

So it's longer, and has larger wingspan. The stronger engines and larger fuel tanks can't be seen from the outside.


Why do suborbital planes feature H-tail and/or large wingtips?

Dreamchaser isn't intended to be suborbital. Don't know about your 3rd picture, but the Spaceship 1 & 2 were designed by the same person/company, so it's not surprising they use the same design elements.

The designs of Dreamchaser vs Spaceship N address two different problems.  An orbital vehicle has to decelerate from ~17,000 mph, while a suborbital vehicle on a ballistic trajectory (simplistically straight up and straight down) starts from zero speed at its high point, and needs to keep from gaining too much speed.  So if I'm not mistaken, a main function of the H-tail is to allow the entire vehicle to act as a drag device.  That wouldn't be practical for an orbital reentry vehicle due to heating & aerodynamic forces.


What is this smoke coming from an F/A-18 shortly before takeoff?

It is not smoke.  It is bleed air being blown behind the heat exchanger which forces cool air across the front of the heat exchanger, this is only happens on the ground. The left side of the aircraft has a secondary heat exchanger that is also cooled by a water spray nozzle.  The water is created by the ECS taking bleed air and cooling it.  The water is blown out by the bleed air so you can see it more on one side than the other. In the picture, it seems to be raining so the air being blown out is more visible because of the rainwater.
-6287 (Fixed-Wing Aircraft Safety Equipment Mechanic, F/A-18)


Does an F/A-18 require a lot of rudder in turns?

I used to be an avionics instructor teaching maintenance type courses for the F/A-18. I have plenty of hours flying in the simulator where I would get the students to conduct navigation flights to familiarise themselves with the operation of the instruments as well as flight controls. I can confirm 100% that the rudder is barely touched once airborne. There is no need to co-ordinate turns as the flight control system does it for you. These things are incredibly easy to fly. It is the controlling of your radios, weapons, FLIR, navigating and keeping an eye on the RADAR all at the same time that is the hard part.


What does this statement about steep descent mean?

The statement is only true if you fly at a speed below the best glide speed. For simplicity, let's look at a glider: Below you see the plot of the L/D ratio over speed of the DG-1000 two-seater glider:

Glide ratio over speed diagram for three different wing loadings (source). If we just look at the lowest wing loading (leftmost curve), the best L/D can be achieved when flying at 95 km/h. Minimum speed is around 62 km/h, so it is entirely possible to fly along at 80 km/h. When the pilot reduces the angle of attack, the aircraft will pitch down and speed up. If it now flies at 90 km/h, he has just improved his L/D from 43 to 46, so he will descend less steeply when dropping the nose.

Note that our flight path angle is now less steep, and the change in attitude is less than the commanded change in angle of attack. Nevertheless, the pitch attitude is reduced and the pilot has the impression that he dropped the nose.

The same is true in reverse when slowing down. When approaching the stall speed, large angle of attack changes will result in relatively small speed changes, so the effect of a steeper descent when pitching up becomes more pronounced as the airplane slows down.

The underlying reason is the fact that drag will increase when the pilot moves away from the best L/D speed. Slowing down will increase drag, and more drag will result in a steeper descent. As soon as he shifts his starting point to higher speeds, things reverse and the aircraft will descend more steeply when the nose is lowered.

Adding an engine will not fundamentally change this behavior. It is only easier to explain when using gliders.


Could the toilet be used as an extra passenger seat?

When I was with Weber Aircraft we provided many lavatories for Boeing aircraft.  There was never any requirement for a passenger in the lav during structural tests/qualification.  Based on this I know that it would be illegal for have someone in the lav during takeoff or landing as it would exceed the structural qual test requirements.


What distance can you see aircraft lights from?

Aircraft lights can be easily spotted 50-60 km away during clear nights.

I used to live in Rotterdam and could spot aircraft at night when they turned exactly towards me at ARTIP which is an initial approach fix of Amsterdam airport Schiphol. ARTIP was exactly 100 km from my house.


Is it the engines or the fuselage that limits service ceiling?

Service ceiling is defined as the maximum altitude at which the aircraft can maintain a specified rate of climb (typically 500 feet/minute for jets).

The service ceiling is dependent on a number of design factors like,

Engine power
Engine efficiency at high altitudes
Wing design

The service ceiling is usually limited by a number of factors, and engine is important among them.

Thrust (or power) decreases with altitude (density) and at some point the aircraft reaches an altitude where even at the 'maximum rate of climb' speed, the engine will not be able to produce enough (excess) thrust to get the required rate of climb. This will be the service ceiling. Usually this is the limiting factor for GA aircraft.
In case of very powerful engines, the wings may stop producing enough lift, though this is rarely the case.
In case of transport aircraft, the service ceiling may sometimes be limited by the maximum altitude from which they can descend to 14,000 ft in less than a specified time (4 min). Commercial airliners are usually limited by this certification altitude.
In commercial airliners, the cabin pressure altitude is held constant (usually ~8000 ft ISA) and the differential pressure will cause stresses on the fuselage, but this is usually not the primary concern as fuselage design incorporates elements (for e.g. relief valves) to relieve pressure when this differential pressure goes beyond a limit.

In short, usually it is the engine, rather than the fuselage that limits the service ceiling.


Why are there full-fledged entertainment systems on aircraft when today everyone has a smart phone?

Here are some points to consider:

The screen size is a huge part of the experience. People with smartphones mostly still view content on a large regular screen when they are home or at a hotel etc. Hence, given a choice a passenger is always going to prefer the larger screen you can pack into the seat back than the relatively smaller smartphone display.
If you can be sure every seat has an IFE screen you can use it for other purposes like mandatory safety announcements & videos. Unless  you can be sure there's no seat without a smartphone owner depending on them for such messages is hard
If you have an existing aircraft the cost & effort to modify it & recertify the changed config. isn't worth it
Smartphones have only become ubiquitous in the last 5 years.
Average fleet age is much more than that. A typical aircraft you fly on might have been built 10, 15 or even 20 years before today.
Manufacturing date is not as important as the design date: If you are flying even in a 5 year old aircraft but the design was made 20 years ago there's no chance the designer could even forsee the smartphone revolution so he put in the IFE.
New designs you can expect modifications e.g. Many recent aircraft have a local USB port you mention & allow the passenger to plug in his device & view his own movies or listen to his own music on the IFE screen. http://www.turkishairlines.com/en-int/travel-information/frequently-asked-questions/on-board/in-flight-entertainment

  Connections enabling passengers to listen to, or watch on their
  individual screens, content on their personal iPods or USB devices are
  available on B777 and some of our A330 aircraft.

The power and waste heat tradeoff of smartphones vs dedicated IFE isn't clear: If you encourage IFE via smartphones you would need to provide charging capacity for simultaneous plug in of hundreds of phones. The electrical resources for that aren't  insignificant.
The devil you know is better than the one you don't: Dedicated IFE is tested & certified with well known characteristics. Having hundreds of unknown chargers plugged in & batteries charging adds other variables to the game. You'd also have to support multiple OSs, screen sizes etc. on the software side.


Testing control surfaces pre flight; what feedback does pilot recieve?

According to this PDF from Airbus (see section "The importance of the pre-flight, flight controls check"), the PF (pilot flying) moves the sidestick around in a defined manner while the PNF (pilot not flying) watches the ECAM F/CTL (flight control) page and calls out "full up", "full down", etc. (Actually the procedure is described in the A330 SOP but the linked document explains it in a comprehensible fashion.)

Source

The ECAM F/CTL page displays the actual position of the control surfaces. This video from Captain Joe explains the behaviour of the sidestick in an Airbus and shows how the control surfaces can be checked on the ECAM F/CTL page (from approx. 1:40 to 2:15).


How to verify the runway numbers in a systematic way given the high workload during landing?

There are a few common (?) techniques you could use, although how you work them into your actual checklists is up to you. Here are some that I've been taught, there are probably more:

Tune the localizer and/or load an approach

Pros: reliable and accurate (if you set the avionics up right) because it gives you guidance for a specific runway
Cons: can lead to fixation on instruments when you should be looking outside; not every runway has an approach; your aircraft may not have the necessary avionics; may be awkward or distracting to set up and verify

Set the heading bug to runway heading

Pros: many pilots do this for takeoff, so it's a familiar check; works for any runway; convenient if you go around and are told to "fly runway heading"
Cons: doesn't uniquely identify a parallel runway

Write the runway number on your kneeboard

Pros: simple; easy to glance down at quickly
Cons: none that I can think of, unless you don't have a kneeboard

Or use all three techniques together, of course.

ATC could still change your landing clearance, or something else could force a change of plan, but stuff happens and you just have to deal with it. Personally I like the localizer/approach method at night and/or at an unfamiliar airport, otherwise I'll just write down the runway number on my kneeboard.


How the stabilizer cutout switch functionality has changed from Boeing 737 NG to 737 MAX?

What do you know, I found the answer to my exact question in the Seattle Times:
First of all, even after two fatal crashes,

Boeing declined to detail the specific functionality of the two switches.

Nevertheless,

The Seattle Times found that the left switch on the 737 NG model is capable of deactivating the buttons on the yoke that pilots regularly press with their thumb to control the horizontal stabilizer. The right switch on the 737 NG is capable of deactivating just the automated controls of the stabilizer.

So far this corresponds to the information I found in the 737 NG FCOM myself.

As Boeing was transitioning from its 737 NG model to the 737 MAX, the company altered the labeling and the purpose of those two switches.
On the newer 737 MAX, according to documents reviewed by The Times, those two switches were changed to perform the same function – flipping either one of them would turn off all electric controls of the stabilizer. That means there is no longer an option to turn off automated functions – such as MCAS – without also turning off the thumb buttons the pilots would normally use to control the stabilizer.

If the above is correct, then not only MCAS, but STS/autopilot as well cannot be turned off on the MAX while keeping electric trim on the control wheel functional.

Peter Lemme, a former Boeing flight-controls engineer, said if the company had maintained the switch design from the 737 NG, Boeing could have instructed pilots after the Lion Air crash last year to simply flip the “AUTO PILOT” switch to deactivate MCAS and continue flying with the normal trim buttons on the control wheel.

(^ bold is mine). This is exactly what I was alluding to in my question. I really want to hear the reasons for the change.

Lemme said he’s surprised that Boeing made the change to take away the functionality that could have allowed the pilots to shut off MCAS without shutting off the electric switches at their thumbs.

Oops.


Are there generic routes all pilots can fly?

In short, yes it is a lot like travel on the road. There are treaty agreements that came from the Chicago Convention on International Civil Aviation in the 1940s which allow quite a substantial freedom of international travel and cross recognition of pilot certificates.

In the USA most routes are open to most pilots, the restrictions are based on the conditions and chosen rules of flight. In an emergency the pilot is legally allowed to do anything needed to address the emergency and get the aircraft on the ground without regard for any routes or other rules, as such I will not mention the emergency exceptions for each separate item and situation.(91.3[b] in an in flight emergency requiring immediate action, the pilot may deviate from any rule of this part to the extent required to meet that emergency)

As you said for driving, the rules of driving may change by country but this applies to all drivers equally, it is mostly the same for pilots.The restrictions for pilot certificates mainly relate to the carry of passengers or cargo for hire not the location or route of flight, similar to the divide between private family car and a taxi or delivery service. Exceptions are the very limited hobby flight categories (ultralights, light-sport, and recreational) but this would be similar to a small moped or Vespa which is not allowed on highways marked above 40mph(60kph).

Flying under visual flight rules generally does not strictly adhere to designated routes. The primary designated routes are federal airways(for the space between) and preferred departure and arrival procedures(near the airport), these routes are actually designed to assist instrument flight rules flight planning and the ATC managing said IFR traffic, however following these routes while VFR is allowed. VFR is literally visual, just look out the window and see where you are traveling. Flying under instrument flight rules will require an instrument rating on your pilot certificate, however the instrument rating applies to both private and commercial certificates.

Certain airports are designated as ports of entry and have customs offices, just like old time marine ports and road border crossings; a port of entry is the first landing after crossing the border, though it may be hundreds of miles from the border. A filed flight plan is recommended to reduce border problems but not strictly required in all cases.(see Chicago convention) A port of entry is open to domestic flights just the same as any other public airport.

There are additional restrictions on the choice of route and airport for regularly scheduled commercial operations, as compared to unscheduled air-taxi and private operations. Also the practical physical limits of the airplane and landing surface; length, width, strength of pavement, climb over local obstacles, etc.

We [USA] have airspace classes A, B, C, D, E, G and "special use". A and B are positive controlled meaning that you must negotiate with ATC for clearance to enter. Most special-use are associated with military training or high security areas, though some are simply alerts or caution areas for other potential hazards such as a large flight school in the area.

Class A is everything between 18000 feet above sea level to flight level 650 (about 65000 feet depending on barometric pressure) and class A requires instrument flight rules which will require both filing a flight plan and an instrument rating on the pilot's certificate.
B is used for the busiest airports, every flight in B must talk to ATC and get explicit clearance to enter B, IFR flights get priority. When ATC is very busy VFR flights that are just passing through and not landing within the class B area may be turned away. B generally covers an area up to 30 miles from the primary airport, though it has a complex shelf structure that steps up as you get further from the airport and allows other airspace below and above the shelves.
Classes C and D are also airport tower controlled but they are smaller than B. C is around secondary international and primary regional size airports, and D is for the least busy airports with a control tower.The main difference is that class C requires a radar transponder with altitude encoding and has a 10 mile radius with one shelf, D has a 4 to 6 mile radius no shelf and no transponder requirement. Both require two way radio acknowledgment from ATC but they do not require explicit permission to enter, planes with no radio can be accommodated if arrangement is made with ATC at least one hour prior.(this is to allow for antique aircraft or flights to repair stations) C, D, and E are controlled but not positive-control airspaces, as such IFR traffic is looked after and kept separated by ATC while VFR traffic just minds its own business for the most part, mainly contacting ATC during landing or for departure. Many D airports are so small they close the tower at night and revert to class E or G pilot-controlled airports.(The Boeing factory airports are all public class D) My local air-force and army-airfield bases are both class D and while I usually just cut through (near my preferred airport and I don't want to take the long way) they do allow some non-military landings with prior permission.
Class E is controlled enroute space, it is all the area between B, C, and D where ATC support is available. Low level Federal airways are all in class E, VOR "victor routes" are the most common type and usually are from 1200feet above ground to 18000 feet above sea level and 8 miles wide, though there are a few T routes [GPS or inertial navigation]. These routes are designed for IFR but they are not restricted, any VFR pilot can fly on them or in between them, though IFR will fly at 1000ft altitudes[eg 5000, 6000] and VFR will add 500ft[eg 5500, 6500]. E also covers air above FL650, though all airspace above FL450 is considered point to point and there are no designated routes. Most airspace above 1200ft is now E, some places E starts at 700ft or at the surface near some airports.
G is all the space between where ATC is not available, also known as uncontrolled airspace, mostly found from ground to 1200ft, where ATC does not have radar coverage G can go as high as 14000ft. G has no IFR because there is no ATC, and no designated airways because there is no IFR, the grey middle is a class G airport with an instrument approach, generally the instrument approach requires minimum cloud base/decision height above the G to E boundary. Flight in IMC is allowed in G without an active flight plan, at your own risk.
Special use airspaces are of several types and can be active only select hours (military training fighters or artillery range) or full time; and they can be only an alert to hazards like heavy student training or moderate military operations; "restricted" during certain hours for heavy military use (though you can still radio the controlling agency and ask them for permission to pass); or fully prohibited.(the only prohibited around here is a ballistic missile submarine base, and it only extends to 2500 feet above the surface)

We also have VFR flight plan filing in the USA, but this is voluntary and not permission to fly. A VFR flight plan is only a statement of intended route and estimated time so that a search can be made if you do not contact the service within 30 minutes of the stated arrival time. Flight plans can be changed in flight or canceled and closed by the pilot over the radio without actually completing the trip as filed. IFR flight plans can also be filed, opened, changed, canceled, and converted to VFR by the pilot while in the air.


Is there any good database for aircraft technical specifications?

One word for the definitive authority on this subject: Jane's.  They'll get you anything you want to know - if the price is right.

Another good source, especially for military aircraft is The Military Analysis Network, run the Federation of American Scientists (FAS).  Great information database and it's free, too!

As with so many other subjects, Wikipedia remains an excellent source of information on aircraft.  It is not a recommended source to cite for writing technical publications of your own, but is a excellent internet portal to additional information and resources e.g. books, periodical articles, etc.


What can I do as a bystander on the ground if I see an aircraft above me that appears to be failing?

Honestly, very little.

First, be clear as to whether you are actually see something failing. If you see flames, or a wing has broken off, then yes, it's a problem. However, if you see someone doing a slow spiral towards an empty field with the power idling, they're more likely to be practicing engine out procedures (something that's required for all US pilots to practice and demonstrate during their checkride for their certificate).

In the event that you actually see an impact, fire, off-airport landing and so on, call 911 and give them your location. They'll send the appropriate crews.

Otherwise, if the aircraft is still flying, there's a strong chance the pilot(s) are already talking to ATC about their problem, if it actually exists. There's nothing you really can or need to do in this case.

Quick Anecdote: I've been told the story of a local police department who gets phone calls virtually every time a citizen lands his small airplane in his private field. Fire/police/medics/etc are summoned, when absolutely nothing bad has happened. This is why you should make an attempt to verify that a problem actually exists before reporting it.


What type of aircraft is depicted in the Taylor Swift music video "Look What You Made Me Do"?

According to Reddit, it is a Gulfstream G650 with the wings cut off, from a Taylor Swift music video “Look what you made me do”.

It has 8 windows like a G650, but is not a real aircraft.

the engine fans don’t look right
the wing leading edge has non-flush rivets and there are too many of them
the window size, shape, and spacing are wrong
there is no front entry door

And no one would be crazy enough to actually cut the wings off a 65 million dollar aircraft.

I don't think it is CGI because of how poorly some of the details are rendered. CGI should be more accurate.

It’s probably a Hollywood prop left over from some movie.


What is the effect of the Load Factor on wing Structures?

https://en.m.wikipedia.org/wiki/Load_factor

As a start for an aircraft the load factor is the ratio of total lift to total Weight

An easy way to imagine this concept is to understand the idea that when the aircraft is flying at high speed during cruise with a small angle of attack the load factor is very close to 1, this corresponds to the first case on the left of the picture here below

Now what is lift, the picture here below is self explanatory, so it is important to understand that the lift is not always an upward vertical force; when the aircraft is under a coordinated bank angle the lift has two components ; horizontal and vertical.

Now to simplify we shall consider the lift to be totally produced by the wings, while in real flight it is the result of the wing, the body, and the tail.

Since the Aircraft is subjected to a load factor of 2 this means the aircraft as a complete body is subjected to a total lift( not vertical) equal to twice the total weight of the Aircraft

The lift produced is therefore: $2\cdot(5000 + 1500)\,\mathrm{kg}\cdot g = 13000\,\mathrm{kg}\cdot g = 128\,\mathrm{kN}$

If we consider we are in the steep banked turn indicated on the right of the picture above:

The weight of the aircraft body without the wings is a downward force on the root of the wings

Also the wings have their own distributed weights, that produces a torque to the root of the wings

Also the distributed fuel in the wings produces a torque to the wings roots

Also each wing is subject to a distributed lift of $\ 6500\,\mathrm{kg}\cdot g = 63.8\,\mathrm{kN}$

The exact computation are difficult because

we don’t know the bare weight of the wing nor the centre of gravity of the wing
we don’t know the distribution of the fuel in the wing, so we don’t know the centre of gravity of the fuel of each wing.

Therefore it is impossible to calculation the shear forces and the torques at the wings roots.

Nevertheless I imagine the main question concerns the relationship between lift and load factor, And here the most important point is to understand that the lift is not always a vertical force


Why would a commercial flight be landing with a tailwind?

Assuming 'I just' means today 17 Oct UTC time, then American Airlines 2539 arrived at 22:52 local, or 2:52 UTC.
Reported METAR at that time:
KBOS 170254Z 32013KT 10SM SCT060 08/01 A3015 RMK AO2 SLP209 T00780011 51027
The winds being 320/13 and runways 22L/R facing heading 215, that means the tailwind component was 3 knots. Well within the 737-800 limitation of 10 knots tailwind.
As for the why, it's to maintain the preferential runway system or to avoid switching back and forth if the anticipated winds will not shift more toward the other end. The preferred direction can be used in tailwind up to a limit (8 knots component in certain places for example).
For the US, acording to the National Safety and Operational Criteria for Runway Use Programs, it's 7 knots for the clear and dry runways.

Under ideal conditions aircraft takeoffs and landings should be conducted into the wind. However, other considerations such as delay and capacity problems, runway length, available approach aids, noise abatement, and other factors may require aircraft operations to be conducted on runways not directly aligned into the wind.
(...)
Where anemometers are installed near the touchdown zone of the candidate runway for landings, or near the departure end for takeoffs, any tailwind component must not be greater than 7 knots.

If there are no TDZ anemometers, then it's 5 knots.
The forecast agrees the winds will stay roughly the same and will shift more towards 220.
KBOS 162320Z 1700/1806 32010G20KT P6SM SCT150 BKN250
  FM170400 33009KT P6SM FEW250
  FM172000 21006KT P6SM SKC
  FM180400 23007KT P6SM SKC

Reading TAF guide: https://www.aviationweather.gov/static/help/taf-decode.php

According to the flight track, you landed on runway 27. And according to massport.com, below is the normal configuration for the NW winds. I should have checked the track first


That is a Silk Way Airlines Ilyushin Il-76. Here is a snapshot from flightradar24 from 13:03 UTC (6:33 PM IST) where the aircraft is approaching Delhi Airport:


What is that yellow square to the right of the main entry door of this Lufthansa A350?

It's a yellow square that says Willkommen / Welcome. In one case I have seen that additional text was written into the square with a black (removable?) marker.

Source
This website explains it like this:

A yellow welcome panel painted beside each of the passenger boarding
doors is now visible on each aircraft. The mark is a flat yellow
rectangle, with the word 'welcome' in both German and English,
accompanied by the iconic logo in the corner. What I love so much
about this - is that that bright yellow warmth is presented to every
passenger, right as they board every aircraft. Upon boarding, each
passenger is welcomed, setting the stage for the onboard experience
and hospitality that will follow. The crew can write personalised
messages to give a more human welcome to this otherwise mechanical
setting.


Here in this amendment to the EASA CS-25 it says on page 4:

  ... for a new Class B cargo
  compartment definition as well as design criteria for a new Class F cargo compartment
  type. This latter class of compartment was introduced because whilst it was concluded
  that manual fire fighting was not feasible for larger compartments, alternatives other
  than just the existing Class C were identified.

And a bit further on page 5 (emphasis mine) :

  ... Further, a new Class F cargo
  compartment definition is added, which is not limited in size and which provides the
  means to control or extinguish a fire without requiring a crewmember to enter the
  compartment. This proposed Class F compartment standard accommodates the carriage
  of large amounts of baggage and cargo loads on Combi aeroplanes as well as in
  compartments of smaller sizes exceeding the new Class B definition. New aeroplanes
  designs can take advantage from the variable solutions under the Class F definitions to
  ensure an acceptable level of fire protection.

And more concrete:

  The AMC further provides guidance for usage of other fire
  protection means in the new Class F compartment such as Fire Containment Covers
  (FCC) or Containers rather than having a liner installed to contain a fire and to protect
  the critical systems and structure of the aeroplane.

I guess it's meant to allow storage of cargo in non-cargo areas (which do not have the adequate fire protection measures such as liners) if other non-traditional measures are installed (such as the Fire Containment Covers)


What options would Qantas Flights 7/8 have in case of emergency?

Although it appears that going from Australia to North America, there is nothing but the great Pacific Ocean underneath. However the truth is (as Federico mentioned) that there are many airports along the way which can allow an A380 to land there, and many more close enough that an A380 can divert to in case of an emergency.

During the early days of this flight (Qantas 8 to be exact), it had to stop at Noumea, New Caledonia for a fuel stop as the pilots thought that it would be safer to do that.

Wikipedia has a list of diversion airports in Pacific. If you turn on the options to view nearby airports on FlightAware and zoom in on the map, you can find many airports.

It should also be noted that not all emergencies require an immediate landing.


What you seem to have found is the Litening Targeting Pod.

  Northrop Grumman's widely fielded LITENING system is a combat proven,
  self-contained, multi-sensor targeting and surveillance system.
  LITENING enables aircrews to detect, acquire, auto-track and identify
  targets at extremely long ranges for weapon delivery or nontraditional
  intelligence, surveillance and reconnaissance missions. Source

pod http://media.defenceindustrydaily.com/images/ELEC_LITENING-AT_on_F-16C_lg.jpg

The F16 does have a cannon as well, but it's located on the port side under and aft of the canopy:


Who does ATC call when a plane disappears with no response?

Most countries have established some sort of Rescue Coordination Centre responsible for search and rescue operations in case an aircraft or ship goes missing. The RCC typically has direct access to various SAR resources such as helicopters. They can also call in local emergency teams (police, firefighting, ambulances etc.)

How exactly the RCC is notified of an incident can be different. It may be through a normal emergency telephone number (such as 911) or via some direct communication channel.


Did people really hand-start big bombers in WWII?

When you shut down a radial the unscavenged oil in the case (oil coating the surfaces that didn't get pumped back to the reservoir tank) runs down and seeps past the rings of the cylinders directly below and to each side at the bottom.  In theory, it can create an hydraulic lock if there is enough oil collected in a cylinder, that happens to be on its compression stroke (both valves closed), and the oil volume is more than the cylinder volume at top dead centre.  Although an actual hydraulic lock is fairly rare (it takes quite a lot of oil), you still have to check for it because if a jug fires on start while one of the bottom cylinders is locked, it'll bend that jug's connecting rod and/or crack the head.

The engine has to be turned with no ignition/fuel to test for this.  Typically it's done by hand as shown in those films.  If you feel a hydraulic lock coming on as you pull through, you turn the engine the other way to back it off and can remove the lower plugs to let the oil drain out.

An aircraft could have propellers that are out of reach of the ground, or there may be some other reason, so you also have the option of doing it with the starter with fuel and ignition turned off.  If there is an hydraulic lock in a cylinder the starter won't be able to do any damage on its own (it'll either bog down or its clutch will slip), so it's safe to do, if done properly.

There is always some oil collected and when the engine is cranked it goes out the exhaust valve when it opens and coats the inside of the exhaust ducting.  The coating of oil takes quite a while to burn off the inside of the exhaust manifold, which is why they belch smoke for 30 seconds to minute after they start.

It IS possible to "hand start" a big radial in a fix, using things like tires slipped over the prop and pulled by a car with a rope, but not by hand unless it's a smaller radial, say under 1000 cubic inches.


What is the usage ratio of the An-225 Mriya?

As a privately-operated aircraft, this is probably not going to be a question which is completely answerable. All that is available is best guesses and incomplete information!

That said, the An-225's last tracked flight on FlightAware – as of today – was March 15, 2012 between Bangor, Maine (KBGR) and Port Harcourt, Nigeria (DNPO). That suggests that the An-225 is either being excluded from flight tracks, or simply hasn't visited the US since early 2012.

Aside from that, the only other likely place for flight information is photo sharing websites like airliners.net and flickr, or on youtube. Browsing through flickr, I tried to track down dates of recent photos in unique locations (which is a guess at best):

May 21 2013
June 24 2013
September 25 2013
September 26 2013
November 12 2013
November 17 2013
December 10 2013

I'm sure there are more, but I stopped searching. It looks like it's probably doing charter cargo trips at most a couple of times a month, which is honestly more frequently than I expected! If you're interested, I'd encourage you to track down more on the sources I mentioned.


Does stall angle of attack in inverted flight change due to the camber of an asymmetric airfoil?

Short answer: Asymmetric airfoils have different positive and negative stall angles, the largest absolute value of the two depends on factors like nose shape and camber. With positive camber (normal and utility aircraft), the negative stall angle can be the largest (in absolute values) but the maximum negative lift available before stall will be smaller than for the positive stall. Larger Reynolds numbers push the stall further away in both directions

It depends on the airfoil. With symmetric airfoils, the stall angle is the same for positive and negative stalls. Positively cambered airfoils (the sort mostly used) have their negative stall at a smaller absolute value of the lift coefficient compared to their positive stall, but the stall angle can well be at a higher absolute value.

Below you see a polar plot for a supercritical airfoil which I used for this answer. The positive stall angle of attack is 8°, while the negative one is around -10°.

Polar plot of the R2A airfoil at Mach 0.6 (own work)

The stall angle depends on details of the nose contour and the camber: Positive camber means that the zero lift angle is shifted to negative values, so there is some bias to negative values in the polar. However, if the lower part of the nose has very high curvature, it will create a high suction peak which leads to flow separation just aft of the nose already at a small negative angle of attack.

One extreme case would be the Göttingen 417a airfoil. Airfoiltools unfortunately plots only a range of Reynolds numbers suitable for model airplane enthusiasts, but the plot below should get the point across. The positive stall angle is 12° at the highest Reynolds number, while the negative stall angle is only around -8°.

Gö 417 lift over angle of attack. The lowest Reynolds number (blue line) is 50,000 and the highest is 1,000,000 (olive green line). Note that all curves are XFOIL predictions - real-world data might look differently.


How are cloud bases and tops reported on PIREPS?

It depends. For a PIREP cloud Heights are reported as they are read by the pilot.

FAR AIM 7-1-16(b)

  ... In reports disseminated as PIREPs, height references are given the same as received from pilots, that is, above MSL.

This means some conditions may be reported MSL as read of the altimeter at local barometer settings while others may be set at standard pressure and read from there. I would assume that altitude reports less than 18,000ft are MSL.


Is there a good reason why modern airliners can't have conventional landing gears (vs. tricycle landing gears)?

Short answer: Yes. Not one, but several. A taildragger configuration for modern airliners comes with several disadvantages:

Visibility during taxiing is much worse.

Visibility while taxiing is a safety-relevant issue (Picture source)

Braking hard will result in a headstand. And with today's landing speeds, braking hard is needed if you want to fly from standard length runways. Carrier-borne aircraft were the first to feel this consequence of increasing landing speeds, so they converted first to tricycle gears.

That is what is colloquially called a "headstand" (Picture source)

Loading and unloading will become more complicated. The current way of sliding containers manually on a flat deck would need to be replaced by internal winches pulling the containers up the ramp to the door.
Drag during ground roll is much higher as long as tail lift is not sufficient to get the tail up. Take-off distances would also become longer.

In short, it comes down to minimizing field lengths and increasing safety.

Who says there are no taildragger airliners? (Picture source)


Is the SEPECAT Jaguar's design aerodynamically inferior to more modern jets?

Only aerodynamics? Then the answer is simple: It lacks artificial stability.

In a paper by Ray Whitford on fighter design he published a comparison study between the conventional Jaguar and an advanced version optimised for relaxed static stability. The improved version is slightly unstable at subsonic speeds and much less stable at supersonic speeds, resulting in much less horizontal tail downforce and reduced size of all lifting surfaces.

Both configurations have the same airfield and combat performance! However, the smaller surfaces and the reduced trim drag improve performance noticeably. Note that this optimization was for the ground attack role; an optimized fighter version would had maintained a larger wing and horizontal tail for higher agility.


Who decides the regular procedure followed by the pilots before takeoff?

The manufacturer will publish a checklist.  Some airlines will choose to use the manufacturer's checklist verbatim, while others will adapt it to their specific operation based on things like safety reporting data from their fleet.  The end result will need to be approved by the regulating authority (in the US, the FAA -- specifically the Certificate Management Office or CMO for that airline) before it's used by crews.

An example of how an airline might modify the checklist would be to adapt it in light of new Human Factors research.  Telling crews to "run this checklist" during some large interval of time (say, between leaving the gate and reaching the runway, or between leaving cruise altitude and starting the approach) can lead to a missed checklist, and research recommends "anchoring" the checklist to some cue that's unlikely to be missed.  So, "run THIS checklist before you release brakes and start to taxi, and THIS checklist when you have about 2000' left to taxi before reaching the end of the runway, and THESE 3 items as you take the runway for departure" gives crews anchor points that they'll observe anyway and leave them less likely to look back and wonder "did we read the Before Takeoff checklist?"

The manufacturer might have made it all one long 15-item checklist that they have crews read "whenever," but the airline could separate out the items that are best accomplished before starting to taxi (knowing that the more items you put here, the longer the delay before the aircraft starts moving), the items that can be accomplished while taxiing (probably not stuff that requires a lot of 'heads down' time like reviewing the FMC routing), and the items that should be delayed until immediately before departure (strobes lights, landing lights, radar etc).


Will I fail a skills test for doing a constant-aspect climb-out?

I fly in the UK, and while there is certainly a "standard circuit" (ie pattern) in the syllabus there are many, many fields that have a non-standard circuit for one reason or another. This is often to avoid antagonizing unfriendly neighbors.

There's also the fact that the NAP is not a rule or regulation, it's more how the airfield management would like you to fly.

I personally don't like the constant aspect climb-out idea at all, it will mean you are paying more attention to aspect than airspeed and looking out for other traffic. It also means that the pattern traffic is not predictable for other visiting your airfield or by others in the pattern. So I would push back on your instructor on this.

As for whether you will fail your skills test if you do it would depend on the examiner's view, and what they are looking for. While a constant aspect departure shows skill, I personally would take a dim view of people doing it despite the published departure procedure, even if it is non-binding. I would discuss it with your examiner ahead of time, and practice your circuits how they say they want it, or at least discuss it with them on the day.


How safe is the single engine taxi out for twin engine aircraft?

I am not aware of mechanics watching civil aircraft start up. They usually have far better things to do. Aircrew are responsible for the aircraft at this point.

The question on a twin is about directional control not safety. How easy is it to taxi on one engine without losing control or stressing the aircraft or tyres in any way? I think this probably depends on the aircraft, some will be easier than others. Also if its a piston twin, you don't want to wait for the other engine to warm up when you are ready for departure. Some four engined aircraft might taxi on two engines - one either side but I've never heard of twins doing this routinely.


Is there any reason in principle that large aircraft couldn't be converted to be controlled remotely?

Yes for reasons of hacking prevention. There is no way to be absolutely sure any interface can't be hacked to crash the plane remotely into a suburb.
Yes autopilots can follow a track of navigation marks to an airfield and can auto-land using the ILS.

But again there is no way to ensure only signals from people who have the best intentions with the plane can activate that mode.


Could a 'wind wall' help to reduce the wind shear problem at St Helena airport?

It's a completely different problem, and I'm afraid something like that would make the wind shear close to the ground actually worse since it is inhibiting air flow within 200 ft of the ground while the wind just above is unaffected.

Plus the additional turbulence created by those thingamajigs sticking up.  Most pilots know how unpleasant it can be trying to land on a runway with a stand of tall trees adjacent to it, with the wind shadow and burble generated by the trees.

The windshear problem for aircraft isn't the wind velocity itself, it's the sudden changes in horizontal velocity at certain levels, which in a large aircraft with a lot of mass, creates large airspeed fluctuations as you climb or descend through, along with vertical flows caused by mountainous terrain can can generate high sink rates that, because of the mass, are slow to be addressed with power.  None of that would be helped by a surface barrier.   All the barrier would do is create an extra nasty shear + turbulence right at 200 ft.


Relative thickness of the airfoil, thickness repartition over span, and low dihedral angle of the entire wing, tells it's a Hurricane.


Why hasn’t the Wankel rotary engine seen more use in aircraft?

They do not have drastically lower rates of failure than comparable piston engines. Their manifest unreliability in automotive applications is one reason they failed so badly in the marketplace. My college materials science TA owned one and had it rebuilt four times. His record for the shortest distance before failure on a zero-timed Mazda rotary engine was 150 miles.
The breakdown mode was failure of the apex seals at the tips of the rotor due to poor lubrication, leading to excessive wear and scoring and the complete destruction of the seals. According to my TA, Mazda went through more than six fundamental redesigns of the apex seal system but never could completely solve the basic problem.


How are sensors in the wheels connected to power and data buses?

For small planes simple systems can be installed that fit on the inflation tubes and replace your standard cap. They use small batteries in the sender units and a little read out.

It looks like Boeing gets their tire pressure/break temp systems from Crane Aerospace. The latest and greatest systems are all wireless

  The Crane 777 Tire and Brake Monitoring System (TBMS) provides
  continuous real-time monitoring of aircraft tire pressure and brake
  temperature. The design incorporates our SmartStem® wireless tire
  pressure sensor with integrated fill valve. The SmartStem uses sensing
  technology with triple redundant sensing channels to provide high
  reliability and accuracy. The Crane TBMS replaces TPMU and BTMU units
  (from the legacy system) with a single Tire and Brake Monitoring Unit
  (TBMU) that interfaces with the existing brake temperature probes. The
  existing wheel interface unit is replaced with an in-axle transformer
  and relay transformer hubcap assembly that allow the tire pressure
  signal to be transmitted magnetically with no physical contact between
  the components. Retrofit of the Crane TBMS requires no change to the
  AMC, EICAS, and CMC system interfaces.

That does not shed to much light on how it all works though. Their handheld system is RFID based and presumably their built in system is similar.