What are the specs for runways at international airports?

Runways for international airports are usually man made, which means that they are made up of asphalt or concrete and sometimes are a mixture of both. The depth for the runways are 29cm to 33cm.
Runways are usually around 150ft wide. For an international airport will have a runway around 6,000ft long, but depending on the size of the aircraft that land there a runway will need to be 8,000ft or more.
I found this link which should give you information on runway maintenance.


What aircraft broke the most [total] world records?

I'm not exactly sure what type of recored you are looking for (civil, military etc.), but a specially modified Su-27 claimed 41 records for altitude and rate of climb between 1986 and 1990. As globalsecurity.org notes:

Between 1986 and 1990, using a specially configured prototype aeroplane T10-15, which became known as P-42, the design bureau's test pilots established 41 IAF-registered world records of rate-of-climb and flight altitude, some of the records being absolute.

P-42 Streak Flanker; image from su27flankerfamily.wordpress.com
Some of these records are given here,

On October 27 and November 15, OKB test pilot Viktor Pugachev added eight climb-to-altitude time records to the table of world achievements in just in two flights-four absolute records for land based aircraft and four records for aircraft with takeoff weight up to 35,274 lb (16,000 kg). Pugachev climbed to 9,843 ft (3,000 m) in 15.573 seconds and to 19,685 ft (6,000 m) in 37.05 seconds.
On March 10, 1987, and on March 23, 1988, test pilot Nikolai Sadovnikov flew the Sukhoi P-42 to 25,528 ft (9,000 m) in 44 seconds, 39,370 ft (12,000 m) in 55.2 seconds and 49,213 ft (15,000 m) in 70.329 seconds.
On June 10, 1987, Sadovnikov claimed a world record for a N category level flight altitude of 63,435 ft (19,335 m).

In some other publications, a number of 27 records have been reported; in either case, it is quite impressive.


If you join the military, dedicate years of your life to service, work hard, show skill and talent, and are lucky enough to be selected, they will train you to be a pilot and fly for free.  You will even earn a modest salary at it.

In the USA, the Army has more pilots than any other branch.
The Air Force, Navy, Marines and Coast Guard all have flight programs as well.


What is the piece that covers the top part of tires?

Those are called speed fairings.

They make the shape over the tire more aerodynamic and reduce drag, thus increasing airspeed and fuel efficiency.

This is a page in a Cessna 172R information manual that comments on the differences in performance when they are installed.


When was the first THS (Trimmable horizontal stabilizer) used and on what aircraft?

If the question is understood to encompass any form of horizontal stabilizer which may be adjusted in flight (with or without a separate movable elevator), then the answer would appear to be Sir George Cayley's 1849 full-sized glider which briefly took flight-- see http://www.flyingmachines.org/cayl.html.  The Wright brothers also used all-moving horizontal surfaces on their early gliders and airplanes, but located in front, as canards.

However, a comment has clarified that the question is meant to only encompass a horizontal stabilizer which may be adjusted for trimming the aircraft, with an attached elevator for pitch control inputs.

According to page 9 of the book "Aces Wild" by Al Blackburn (see this Googlebooks link), the first use of an in-flight-adjustable horizontal stabilizer was in 1929 by Clarence Gilbert Taylor in his B-2 "Chummy", which eventually evolved into the Taylor Cub and then the Piper Cub, all of which used the same stabilizer trim system.  Naturally, all these aircraft featured an elevator attached to the adjustable horizontal stabilizer.

The same source says that many old Waco biplanes used the same feature.  In this photo of a 1936 Waco biplane, the slot associated with the adjustable horizontal stabilizer is clearly visible.


How is drag created from wingtip vortices?

Wingtip vortices don't create drag, just as wet streets don't cause rain.

Lift creation and viscosity create drag. Drag is composed of pressure drag and viscous drag, and induced drag is one part of pressure drag. Unfortunately, the Internet is full of memes which attribute induced drag to those wingtip vortices, but some swirling air behind a wing can hardly cause any drag, can it?

See it another way: If the wing were not creating any lift, the air would not flow around the tip and curl up. So why don't we read that the tip vortex is the source of lift? This uses the exact same logic as saying that the tip vortex creates drag, and is equally wrong.

Wingtip vortices are just the tip of a full vortex sheet which leaves the wing. This vortex sheet is the consequence of the wing accelerating air downwards. Now instead of repeating myself all over again, please allow me to point you to the many other answers which explain what is going on:

This answer explains in detail how lift is created and how the downward acceleration of air is accomplished.
This answer goes into the formation of the wake and the wingtip vortices.
This answer shows why more wingspan reduces induced drag. It matters little whether the wingtips are turned up, down or continue straight: A larger wingspan reduces induced drag.

Winglets increase the amount of air involved in lift creation and reduce induced drag for the same lift. In most cases they are used to create more lift with the same geometric wingspan without incurring a disproportionate drag penalty.


Why do pilots need the ceiling, time, and dew point in the ATIS?

The ceiling is the lowest altitude where clouds cover more than half of the sky. This is important because climbing above that altitude means you will most likely have to fly through clouds. This makes navigation more difficult and pilots are required to have special training to fly in low visibility. If the ceiling is too low, pilots can't be at a safe altitude above the ground and out of the clouds at the same time. Low ceilings are also critical for landing, and may require pilots to make an instrument approach and landing.

Zulu time refers to UTC time, which is the universal coordinated time. Zulu or UTC time is helpful as a worldwide reference in fields like aviation, to avoid issues like dealing with changing between local time zones. The ATIS will contain the Zulu time that it was updated so pilots know how recent the information is.

The dew point in relation to the temperature gives the pilots information about the humidity, and can affect visibility. If the dew point is close to the temperature, humidity is high, which can cause hazy conditions, or even fog. As with the ceiling, this can warn pilots of possible changes in conditions that will make it harder to see the ground or other aircraft while in flight. In terms of aircraft performance, the dew point is also needed to determine the true density altitude, when combined with the pressure and temperature. A high dew point means a higher density altitude, which reduces aircraft performance.

Dew point is also very important in certain helicopters with carburetors, like the Robinson R-22 and R-44 helicopters, which are subject to carb icing even during take-off because they only use as-required power rather than full throttle. In this case, carb heat needs to be applied whenever the temp/dew point spread is 15C or less. Here is the citation from the R-22 POH:


Why angle of attack is always shown against the relative wind parallel to horizon?

I think this has been at least hinted at in other answers, but, just to put it succinctly, the diagrams aren't actually intended to show the airflow as always being parallel to the horizon. The airstream is just shown flowing along the horizontal axis of the graph because it's convenient to illustrate it that way. There is no implication intended in the diagram that the horizontal axis of the diagram is actually parallel to the Earth's surface.
The behavior of the airfoil is exactly the same regardless of the actual orientation of the wing and airflow relative to the horizon. All that matters is how the airfoil is oriented relative to the airflow. You can rotate those diagrams any way you want relative to the horizon and what they depict will remain true.
The blue airflow lines you've drawn on the diagrams seem to be assuming that the airplane is always climbing at an angle roughly equal to the angle between the horizon and the wing's chord line, but this is not true. You can fly with a high pitch-up angle while maintaining level flight if you fly slowly enough, for example. You will practice this (called "slow flight") when training for a private pilot certificate. You can (and often do) even descend with a nose-up attitude. And, if you put the nose up too far, you can descend very rapidly with a nose-up attitude after your wings stall. For example, Air France 447 was falling 10,000 feet per minute with a nose-up attitude as one of the pilots held the stick back.


F/A-18E and F/A-18F Rhinos: What's the difference?

The only major difference between the E and the F is the extra seat and its consequences (lower internal fuel capacity, lower landing weight etc).

  Fuel Capacity internal: (F-18E) 14,400
  lb (6,530 kg) (F-18F) 13,550 lb (6,145 kg)

http://www.aerospaceweb.org/aircraft/fighter/f18ef/
(data and own sources on the bottom of the page)

It also has a lower "Carrier Bringback Payload".

  Carrier Bringback Payload F/A-18E: 9,900 lb (4,491 kg) F/A-18F: 9,000
  lb (4,082 kg)

http://www.boeing.com/defense/fa-18-super-hornet/#/technical-specifications


How to simulate magnetometer used on navigation system?

The unit does not really matter if you measure the right quantity. But obviously angle magnetic induction and angle are different quantities. Typically—but it might depends on the type of magnetometer used and is not true e.g. of mechanical compass—there will be two or three magnetometers detecting components of the magnetic induction vector, and then you calculate the bearing to magnetic north, and if you have three components the inclination from those.
The raw output of an electric vector magnetometer, measuring one axis of the magnetic induction vector, will be a voltage. You can convert it to the inductance in μT or whatever unit, but for navigation you only care about the direction and the units cancel out when you calculate that so you don't have to.
For magnetometers intended for nagivation, the required accuracy is only specified for the angle, in degrees, because the magnitude is not used.


At present, all US military aircraft follow the 1962 United States Tri-Service aircraft designation system. The first letter ('F' or 'B') denotes the mission of the aircraft, while the number denotes the design number. The designation system produces a Mission-Design-Series (MDS) designation. From Designating and Naming Military Aerospace Vehicles:

4.1. Designator Definition:
4.1.1.The  MDS designator is an official DoD recognized alpha-numeric symbol designation of a military defense aerospace vehicle. .... The designator describes the aerospace vehicle in two components where the components are separated by a hash.The first component, comprised  only  of  alpha characters, describes the mission of the vehicle.The second component, comprised of both alpha-numeric characters, describes the design number and design series of the vehicle.
4.1.2. Standard  aircraft MDS designators are comprised of the following: status prefix(optional), modified mission(optional), basic mission(required), design number (required), design series (required).

The document also gives some examples of this implemenatation:

Both tables from Designating and Naming Military Aerospace Vehicles
The 1962 system replaced the earlier system, where each service had their own systems in place for naming of aircraft.

From 1924 - 1962, the USAF (and the USAAF before them) used the 1924 United States Army Air Service aircraft designation system.

During the same time, the USN used the 1922 United States Navy aircraft designation system.

Once the USAF was formed from the USAAF in 1947, the US Army followed the 1956 United States Army aircraft designation system till 1962.

Before all of these was the 1919 United States Army Air Service aircraft designation system.

More details about the aircraft designation can be found in this page.
Basically, the counters were reset while the 1962 sytem was adopted, leading to unrelated sets of aircraft numbering. As for individual aircraft numbering, there has been a number of cases where the system was not followed, like the F-117 Nighthawk.
Adherence to this system has been patchy at best. So, you have B-1 Lancer and B-2 Spirit after B-52 Stratofortress (this was due to the counters being reset), while the next bomber has been named B-21 Raider.


What is this four-engine propeller airplane?

I believe it's an Ilyushin Il-18. Pic from here:


The tow line has the "Y" connection to a pipe/rod along the leading edge of the banner.  This keeps the leading edge perpendicular to the tow direction.  The bottom end of the pipe/rod is weighted so that once in the air gravity will rotate the banner to the vertical.


Will the Boeing 737 be built with a geared turbofan engine?

The current 737 NG has only one engine choice, the CFM-56. Although this means less choice for the customer, it allows the manufacturer to focus on supporting only one type of engine. The comparable A320 has options for the CFM-56 and the V2500.

The A320neo effectively replaced the CFM-56 with the LEAP-1 and the V2500 with the PW1000G. The 737 MAX will replace the CFM-56 with the LEAP-1, and continue to provide only one engine choice. Note that on the A320neo both engines offer comparable performance overall, and orders are basically split between the two.

Although the 737 MAX is behind the A320neo in sales, it's unlikely that adding another engine choice would make much difference for the considerable expense it would require. The cheapest option is to use the PW1000G, and that still requires a lot of work for the manufacturer to integrate it into the airplane, and then test and certify the 737 with that engine. As with the LEAP-1 and CFM-56, Boeing would prefer to have their own minor version of the engine certified, which adds more expense. There's just no incentive to add another engine option at this point.

A future version of the 737 could possibly use a geared turbofan, but it's too early to tell if such a version will even be built. It certainly remains an option for future designs as engine manufacturers develop the technology further.


Mind you, not all aircraft need one, especially slower piston ones.

As you get closer to higher speeds, where compressiblity becomes significant, and you are approaching the speed of sound, the air starts to behave differently aerodynamicaly.

Also: remember how the air is a little bit accelerated over the wing because of the shape of the wing? Well, if you fly close to mach 1 and accelerate the air even further, a little bit of that air is now moving supersonically over the wing. And you now have a shockwave on your wing.

The plane might start pitching down (wing momentum changes), wing stalls (yeap, from too much speed), aerodynamic center moves etc, flight controls might stop working. Google ‘Mcrit’ and ‘mach tuck’ for more, but there are a lot of bad things generally happening in that region.

What it all boils down to is that the wing now has a built-in limitation by the engineers:do not fly faster than (say) mach 0.9 or you will be in trouble.

Now that we have a speed limit that depends on the speed of sound, we really need an instrument to show the pilots when that limit is approaching.


Will manned aircraft have to defend ground targets against unmanned aircraft in the future?

Some advantages of UCAVs over manned aircraft in the strike role:

The enemy doesn't gain hostages when they get shot down over enemy territory
The numbers that can be deployed are limited by the rate at which they can be turned out on automated production lines, not by the time it takes to train a combat fast jet pilot to a high standard (about 5 years minimum)
The UCAV can potentially be much smaller than a manned aircraft, if a reduction in range is acceptable, reducing the radar signature and vulnerability to air defence systems
As a result of 3, the UCAV can potentially be based nearer the area of operations and launched by catapult or using a rocket booster, leading to a shorter reaction time

In a scenerio where manned aircraft are intercepting UCAVs it is probably reasonable to assume that the UCAVs will have an advantage in numbers. UCAVs engaged in tactical missions will probably operate at low level and rely on superior manouverability and short range missiles to defend against attacks by manned fighters.


How, exactly, did US1549 land on the Hudson?

The NTSB report is a great resource when looking for information about an incident like this.

There is an Engine Dual Failure Checklist discussed starting in section 1.17.1.2 of the report. This includes steps to attempt restarting the engines, and further steps depending on whether or not the engines can be started, and finally steps to help prepare for a forced landing. Pilots train on engine failures regularly, so they are already familiar with the procedures. The report discusses how their actions compared to what the checklists say. Since the incident occurred at such a low altitude right after takeoff, they didn't have time to complete all of the steps. They did what they had time for, and had to make quick decisions about what their options were.

The report also discusses in section 1.17.3.2 the ditching training the pilots received. There was guidance in the manual, but no specific scenarios included in their simulator training.

The autopilot is great for use in normal situations. However, as soon as anything is going wrong, the pilot should take control of the plane. You do not want to take time to figure out "what's it doing now" in a difficult situation. So in this situation, the autopilot probably disconnected when the engines went out, or was manually disconnected by the pilots.

Section 1.6.3 talks about the flight envelope protections. I believe these protections are what you are referring to when you say that the autopilot has more control. They are designed to protect the plane from stalling or otherwise exiting controlled flight. Because the pilot was able to start the APU to provide electrical power, the plane remained in the "normal law" mode where these protections were available. This limits the control the pilot has in order to protect the plane, in the sense that the plane will override pilot inputs to avoid dangerous situations.

Section 2.7.2 discusses the impact of these protections in this case.

  The airplane’s airspeed in the last 150 feet of the descent was low
  enough to activate the alpha-protection mode of the airplane’s
  fly-by-wire envelope protection features...

  Because of these features, the airplane could not reach the maximum
  AOA attainable in pitch normal law for the airplane weight and
  configuration; however, the airplane did provide maximum performance
  for the weight and configuration at that time...

  The flight envelope protections allowed the captain to pull full aft
  on the sidestick without the risk of stalling the airplane.

An interesting point in the report is that Airbus certified the plane to be able to land on the water intact under certain conditions. Here is how the actual conditions compared to the certified conditions.

Section 1.6.7

The report mentions that it would be extremely difficult to meet all of these requirements in an airplane with no power. The values that are higher, notably the mass and descent rate, are factors in the damage the airplane received.


As per the FAA's legend they are referenced to magnetic north

  Compass rosette will be based on the five year epoch magnetic
  variation model.


What is the thrust balance between compressor and exhaust nozzle for a turbojet engine?

The answer depends on two major factors: the engine design, and the flight speed.

Engine design. As mentioned in this answer, there are four major types of turbine engine design: turbojet, turbofan, turboprop, turboshaft. The turbojet has all air flow through the engine itself and derives all thrust from the combustion gas jet exhaust. At the other end of the spectrum, the turboshaft has negligible thrust from the hot exhaust and transfers all useable power to the output shaft.

Flight speed. At high speed (case a in above picture) air streams into the inlet at high velocity and is decelerated before it hits the compressor, which sees a static pressure at the front that is higher than ambient pressure. No suction at the compressor from end at high speed! Only at the lower speed of case b is the static pressure at the front of the compressor lower than ambient.

To start with the last question:

  I believe that helicopter turboprops produce no measurable thrust in the jet. Anyone?

Helicopter engines are turboshafts, which transfer all useful power onto the output shaft. No thrust from the exhaust stream here, ratio 100/0

Then the title question, which is a bit confusing because of the use of the word suction. IF we take the question as posted in a comment, it seems to focus on turbofans, and on the thrust ratio between hot stream and cold stream:

  The compressor acts as a tubed multi blade propeller. It compresses the airflow and the reactive effect is thrust on each rotor blade. What is the ratio between the thrust developed in compressor and the thrust developed in the exhaust nozzle?

Two sources for the answer:

From The Jet Engine 5th edition by Rolls Royce, page 94:

  A compressor is a device that raises the pressure of the working fluid passing through it - in this case, air. A fan is a large, low-pressure, compressor found at the front of most modern aero engines.

  For a modern large civil engine:the fan passes over one tonne of airflow per second; this flow produces around 75 per cent of the engine thrust

Gas Turbine Theory by Saravanamuttoo a.o. example 3.2, finds a ratio of 73.5% at sea level:

   Thrust of a twin-spool bypass engine with the following data:
   * Overall pressure ratio           25.0
   * Fan pressure ratio                1.65
   * Bypass ratio                      5.0
   * Total air mass flow             215 kg/s
   * Fan thrust (cold stream)     52,532 N
   * Exhaust thrust (hot stream)  18,931 N

These above percentages are from the engine itself - but in cruise flight, a large part of thrust is developed by different structural parts of the engine, notably the engine intake.

A supersonic turbojet engine with central intake cone, from an old paper format uni lecture book. The inlet starts developing thrust at below M = 1. A subsonic engine has its inlet optimised for lower velocities and contributes more to the thrust in cruise.


Why is this unit attached to the main landing gear not a common unit for towing or pushback?

I think it might not have enough clearance for smaller aircraft, while a towbar would work with pretty much everything.

Also the force you apply needs to be pretty much the same, independent from where you push/pull, as you only need to overcome the rolling resistance of the landing gears. The airframe and landing gears are sized for much larger loads, so there is not a lot of saving in my opinion.


Steady-state simulation of pitching motion

A "steady" rate of pitch condition is very rare because most aircraft are designed to be stable enough to avoid stalling themselves.  In other words, the more you pitch, the greater the control input you need to continue increasing AOA.
You can reach steady state in roll easily.  Here drag resistance to rolling will stabilize roll rate, provided the aircraft rolls smoothly around its axis.  Here, rudder and elevator inputs may be required.
So, for pitch, you could get a steady state pitch (relative to the horizon) in a loop.  Here, throttle inputs are definitely required (to get a perfect circle).
But for increasing AOA at a steady rate, this will lead to a stall.
There is also the analytical consideration of acceleration before reaching steady state.  Taking the easiest, the roll, roll rate goes from 0 degrees/second when ailerons are applied to steady degrees/second when drag force = rolling force (differences in AOA of rolling wings helps too).
Many early "video arcade" games do not simulate the acceleration (the deer is instantaneously in full gallop). To do an accurate simulation, acceleration to steady state must also be considered, so now you have a rate of acceleration to steady state.


If you are referring to the angled pieces above the front window, and below the nose; they are referred to as the WSPS (wire strike protection system). Designed to shear a line before it wraps around the landing skids or rotor.

Related post: Is special equipment required to perform high-voltage line inspections?


What is the difference between low energy warning and alpha floor in A320?

Low energy warning is a function of Flight Augmentation Computer (FAC). It monitors aircraft’s flight path and warns if speed is about to decay below the threshold where power is needed in order to maintain positive (ie. climbing) flight path with pitch control.

Alpha floor is provided by auto thrust (A/THR) - (commanded by FAC), which sets full thrust (TOGA) regardless of pilot input if angle of attack rises above pre-determined angle. The threshold depends on aircraft configuration.


The simplest answer to your question is that the F-16 has not yet been retired because, for its cost, there's nothing better being built in enough numbers to replace the nearly 4500 Falcons produced.

The F-16 was designed on the trailing edge of a surge in technological development by the U.S. military in the wake of Vietnam. The U.S. had fought that war with an air force primarily designed for a standoff engagement with the Soviet Union directly, thus emphasizing interceptor-style fighters targeting bombers at extreme range using missiles. Robert McNamara, U.S. SecDef for the Johnson and Nixon administrations, also emphasized a "one-size-fits-all" approach to aircraft design, requiring the USAF and Navy to collaborate on common aircraft designs that covered a multitude of mission profiles. This created the F-4, a fast but heavy plane that was a handful to fly, weaknesses that were exploited by pilots of technologically-inferior MiG-19 and MiG-21 aircraft in close combat engagements that the Phantom was ill-prepared to fight.

The lesson "dogfighting isn't dead" prompted a renaissance in jet fighter design in the 70s, producing the F-14 and F-15 long-range air superiority fighters, and the smaller F-16 and F/A-18 multirole fighters. Maneuverability, a wide range of weapons from guns to long-range missiles, and high pilot situational awareness by reducing workload and integrating flight and fire control systems, were all emphasized strongly.

The Soviets were taken somewhat by surprise at this surge; as of when the F-16 first flew, the Soviet air force and those of its allies had nothing that could compete. They answered a few years later with the MiG-29, a smaller twin-engine design similar to the larger Su-27 which was in pre-production to answer the F-15. These six fighters - F-14, F-15, F-16, F/A-18, MiG-29 and Su-27 - represented the cutting edge of fighter design as of the collapse of the Soviet Union in 1991.

The new U.S. designs to enter production since, the F-22 Raptor and F-35 Lightning II, are themselves fairly old; the first production F-22 was built in in 1996 and flew in 1997, almost 20 years ago, the result of a design competition with planes flying back in 1990, and the initial RFP originating in the 1980s. The F-35 first flew in 2006, itself derived from the X-35 JSF testbed which first flew in 2000, so that design is between 10 and 15 years old now depending on how you count. Their protracted development times are a direct result of the reduction in pace of the U.S.-Russian arms race since 1991; with no other technologically-advanced military adversary on the horizon, there simply hasn't been the impetus to get these planes out to the front lines (there is some civilian talk of restarting the F-22 production line to bolster Raptor numbers, as the Sukhoi PAK-FA and Chengdu J-20 are very close to production and the F-35 is way behind projections and proving a disappointment so far, but another 100 new Raptors are projected to cost a ludicrous $225 million each due to increased costs of restarting the line and producing them in parallel with the F-35).

The F-35 also had the handicap of being a return to the "one-size-fits-all" design mentality, being intended as a replacement for practically everything besides the Raptor in the U.S. air arsenal, Air Force, Navy and Marines, with an F or A in its designation. That's caused a lot of technological headaches, since any replacement for the Marines' AV-8B Harrier is going to need STOVL capability, and the Navy and Air Force have always had a different though overlapping set of requirements relating to the Navy's basic need to operate aircraft from a ship at sea that's maybe a fifth as long as the USAF's minimum runway length requirements for its airbases. The resulting design is big, heavy, and relies on the most powerful single engine the U.S. has ever put in a fighter, which pushes the boundaries of the stress limits of the materials we use to make jet engines.

Lastly, military spending in the last 10 years or so has been preoccupied with developing and fielding technology to fight a low-tech insurgency; our enemies know they can't beat us in a toe-to-toe fight, so they don't fight that way, instead targeting our multi-million-dollar military hardware with Vietnam-era milsurp RPGs and oil-drum IEDs costing maybe $100 a shot. On this kind of battlefield, stealth air-superiority aircraft are kind of redundant as the enemy doesn't even have radar, much less an air force to exercise superiority over. That's why the F-22 has never seen real combat; the U.S. has enjoyed "air supremacy" by default in its primary combat theaters, as its enemies have never fielded an air force to speak of.


Which "Power Available" graph is more correct?

Power is work getting done over a period of time.
Work is force multiplied by distance.
So when you are sitting at the beginning of the runway, at full throttle and brakes on, while thrust available is very high, power available is 0, because no “work” is getting done.
Edit- basically you are applying a lot of force, or using a lot of thrust, but since distance traveled is 0, no work was actually done.
Which is why the power available is indeed 0 at a velocity of 0, and increasing rapidly.
Note- the second graph is exactly the same as the first, only it is showing the curve beginning at some point after the stall speed.


Is it possible to fly with counterbalanced single blade engines?

Both Bo-102 and 103 were experimental aircraft, with Bo-102 more of a jig than an actual aircraft. They were used a testbed for various technologies and the single blade rotor is only one of them , with the main thrust being in the development of (hinge-less) rigid rotor and (glass fiber reinforced) composite blades.

The single blade rotor offers some advantages over the (normal) multi-blade configurations like,

The blade passes through 'clean' air and is thus more efficient compared to the multi-blade configurations, where the (following) blade passes through the turbulent (wake) air from the previous blade, at-least in hover.
The single blade propeller is compact and for this reason, is used in some self launching gliders which fold their propellers inside their fuselage,like the Alisport Silent 2 Targa.

However, there are significant problems associated with this design,which makes it (mostly) unsuitable for widespread use.

For reducing vibrations, the blade has to be counterbalanced by a mass, which is practically dead weight. While this may be acceptable for small and lightweight propellers used in gliders, this is a major problem in helicopter blades, which are significantly heavier. For example, the Mi-17 Main Rotor Blade weighs ~140 kg.
If the mass is  kept low, the lever arm is huge and this increases drag.
Though the blade may be  balanced at the pitch axis (to reduce vibrations), torque induced in the rotor blade (due to lift) will cause significant vibrations. As the torque is increased, if the weight is fixed, the rotor will tend to rotate the engine and rip it off. The only way to prevent this is to balance the blade, both aerodynamically and centrifugally, which is easier said than done.
The same problem arises as the drag of the blade is different from that of the mass arm, with a torque being created parallel to the axis of rotation.
The rotor blades usually 'cone' in flight; this means that the lift vector is slightly tilted towards the center, not concentric with the rotor plane.
The blade has aerodynamic forces acting on it while the balance weight does not. Due to this, the precess differently, which causes unbalance and vibration.


Within Europe, whenever there is need to reduce the number of flights through a certain airspace, the Network Manager (Eurocontrol) puts in a so called "regulation". This results in flights planned through the regulated airspace being delayed or re-routed.

Regulations are given an ID; those starting with KALP are from the Karlsruhe Upper Area Control (EDUU), southern sectors (Alps) above Flight Level 315.

Since your flight was over three weeks ago, I can't check the exact "regulation Id" in the public database, but it is likely that it was related to staffing issues at Karlsruhe upper area control centre.

An example of a current regulation starting with "KALP" is below:

Karlsruhe UAC has severe staffing problems and is causing many traffic delays this year.

A delay of 6 hours due to a regulation sounds extreme to me. I don't know what the origin and destination of the flight was, but typically a re-routing avoids the regulated airspace with only a short delay.


Is there an aircrew bunk in the 747 cockpit?

Yes, there is a crew rest with two beds (bunk) connected to the cockpit on the 747. As MainMa notes, this can be found on 747-400 or 747-8 models, but not the older models. It can be seen on the seating charts here:

The crew rest is directly across from the two lavatories. While the lavatories open into the aisle of the cabin (grey area), the crew rest opens into the cockpit. There is a layout here that shows a how the upper deck is arranged. It's a freighter, but is was converted from a passenger plane, so it has the same crew rest location.

With the introduction of the 747-400, the position for the flight engineer was removed (seen below), with those functions being replaced by computers. This opened up a bit of room behind the pilot seats.

Source


Where can I find a list of internal airline designations for various aircraft/cabin configurations?

Internal designations are usually used to differentiate various seating configurations or differences internally for an airline. From your example, all those codes are various codes for the 757-200 (at Delta, they code the 757-300 as a 75Y). You can often look up various seat configurations at Seatguru.com, a site that generally tracks seating information on airlines. Additionally, all would be sent to ATC using the ICAO type B752.

The reason for these variations can be broken down to a couple areas of differences. One is exit configuration; in the same type (757-200), there can be 2 or more different configurations of emergency exits (combinations of doors and windows, and various types). If you have a fleet that mixes these, you'll often have to have different seating configurations for them. Another differentiation could be whether there is a subfleet equipped and used for ETOPS flights. There can be other reasons an airline could want a subfleet and a different cabin. Also, if you're in the process of upgrading a fleet, you might want to create codes to differentiate them so you know which is going where and be able to plan your revenue models around that.


Is there a database of airfoils for a given Reynolds number?

Reynolds Number is calculated as:  velocity × chord/kinematic viscosity of air

velocity is meters/second, chord is meters, kinematic viscosity of air is around $1.48 × 10^-5$

Then go to Airfoil Tools.
As you make your selections, you can see, in the polar diagrams, the effect Reynolds number has on the lift and drag properties of your wing.

A typical ultra light will have a Reynolds Number around 500,000 to 2 million.  A possible path to a solution may be to study aircraft of similar size and speed range.  These have been in existence for more than 100 years.

You may find a heavily cambered rectangular wing (Aspect ratio around 6-8) with a blunt rounded leading edge will give good low speed performance and very docile handling characteristics.  Variations at this Reynolds range will be mainly in amount of undercamber you choose,  depending on speed range you prefer and engine power.

The NACA 4418 may be a good place to start.


Would "wind turbine generators" in the bypass stream save fuel for jetliners?

There are a few Alternators on big planes.

Most large aircraft have an APU which is often in the back of the aircraft. It is effectively a small turbine directly bolted to an alternator. It provides power while the plane is on the ground (and the engines are off) and can also be used in flight if need be to supplement the main system or in the event of a main engine failure.

The engine alternators are generally mounted and driven directly by the turbine (via a transmission) in this case near the compressor stage. You can read more in this thread and check out this video for a nice overview/explanation of jet accessory drives. You can also see where in this picture,

(source)

As mentioned in the comments you can have a Ram Air Turbine driven by airflow but these are presumably not as efficient as directly mounting it to the engine.


Are there general accuracy requirements for aircraft power supplies?

Short answer:

Operational voltages on the 28 V bus may range from 22 V to 30 V.
Abnormal voltages on the 28 V bus may occur from 0 V to 60 V.

The detailed requirements depend on the manufacturer, the type of plane and the jurisdiction.

USA: MIL-STD-704

US military standard MIL-STD-704(F) Aircraft Electrical Power Characteristics defines electrical properties of military aircraft equipment. For instance the 28 V DC bus is specified as:

A similar standard should exist for commercial aircraft, unless they just apply MIL-STD-704 as well.

Europe: ISO 1540

In Europe there is ISO 1540:2006 Aerospace -- Characteristics of aircraft electrical systems. This standard differentiates by the actual power source:

Category A: TRU (transformer)
Category B: engine driven DC generator
Category R: regulated DC power from active converter

Category A and B are specified identically for their DC characteristics. Category B is the worst case for AC ripples. Category R is the best case, as it is already regulated. Nevertheless, connected equipment needs to cope with the worst case, that is category B (engine driven generator).

ISO 1540 specifies the 28 V DC bus characteristics (summarized) as:

28 V DC bus - Normal operation: 22 V - 30 V
28 V DC bus - abnormal/onset: 0 V - 60 V


Can TRACON increase plane speed on approach?

Yes, we can ask pilots to speed up on approach, but it is discouraged and not commonly done. This is because, as an aircraft approaches an airport, the crew will configure it for landing. This includes lowering the flaps, which lowers a number of reference speeds - essentially, making them unable to fly very fast. In order to speed up, they would have to raise the flaps again, which would result in extra workload and bad fuel economy.

The controller you heard knows this. They used the phrase "if able" to emphasize to the pilots, that they only had to comply if it was convenient for them.

ICAO provides the following guidance (form Doc 4444):

  4.6.1.3    Speed adjustments should be limited to those necessary to establish and/or maintain a desired separation minimum or spacing. Instructions involving frequent changes of speed, including alternate speed increases and decreases, should be avoided.

  ...

  4.6.3.5    Arriving aircraft should be permitted to operate in a clean configuration for as long as possible. Below 4 550 m (FL 150), speed reductions for turbojet aircraft to not less than 410 km/h (220 kt) IAS, which will normally be very close to the minimum speed of turbojet aircraft in a clean configuration, may be used.

  4.6.3.6    Only minor speed adjustments not exceeding plus/minus 40 km/h (20 kt) IAS should be used for aircraft on intermediate and final approach.

  4.6.3.7    Speed control should not be applied to aircraft after passing a point 7 km (4 NM) from the threshold on final approach.


Is taxiing a small aircraft on a residential street legal?

It doesn't matter whether or not the road is residential, it depends more on public or private. If the road is a public road, taxiing an aircraft will usually not conform to state motor vehicle regulations without a pilot car and a permit. In rural areas where nobody cares, it doesn't matter. When there are enough people around somebody will object, and then it does matter.

An airpark preserves community access to a runway via residential roads by making them private, and not subject to state or local motor vehicle law. Rules are enforced by conditions on titles to property, or by reference on the title that the property is subject to rules made by an HOA or other organization of the sort. Look at your title.

I think it unlikely you bought into an airpark without knowing it, but if your street signs look like this, taxiing on the streets is probably legal.


Does leading-edge droop increase or decrease lift, other things being equal?

From this NASA study on LE flap/droop for a light general aviation wing:

Variations of lift are small up to $\alpha$ 10°, but the stall is delayed to a higher angle of attack (and $C_L$) for a full-span droop (see: How do droops help to avoid stalls?).

And from a NACA study published in 1954 (NACA-RM-SA54B16) on the Effect of a Leading-edge Flap upon the Lift, Drag, and Pitching Moment of an Airplane Employing a Thin, Unswept Wing:

The variations of lift with angle of attack and of pitching moment with lift near zero lift were not significantly affected.

In general at all test Mach numbers, the drag at zero lift increased with flap deflection.

The maximum lift-drag ratio was increased at subsonic speeds, and the increment in the maximum lift-drag ratio for a given flap deflection decreased as the Mach number approached unity. At supersonic speeds, flap deflection had no influence upon the maximum lift-drag ratio.

(Above plot shows the round leading edge data at Mach 0.6; left-to-right: $C_D$, $C_L$, and $C_m$.)
Note: The second study is on a thin airfoil, but the core premise (reduction of incidence and increase of camber) is covered here.


What prevents someone from hijacking a radio frequency mid-air?

This sounds like a “people problem”. That kind of problems is best solved with enforcement.

Source of radio broadcast can be localized and it is not particularly difficult. There are techniques for transmitting something secretly, but they need specific modulation. Rogue broadcast or jamming on simple AM voice channel will be trivial to triangulate.

So if somebody did it, the FCC or FBI would pull out appropriate equipment, hunt them down and throw them in jail. Broadcasting without license, or contrary to the license you have, is in itself a crime and they'd throw in charges for endangering, which are quite serious.

Now of course it would take some time to hunt the perpetrator down. However, the situation is not that dangerous. Basically it could be treated as communication failure. VFR flights would continue flying visually, IFR ones would follow last clearance and then as filed, landings can be cleared with a light gun. And then either the surrounding sectors would be OK, or the pilots would probably try to establish some alternate communication. Cell phones should work fine for small aircraft while airliners would probably use HF or Sat links to dispatch and ask the dispatcher to relay.


How do pilots get enough sleep in preparation for a long night flight?

Short answer: Sleep aids cannot be used this way in the US. FAA regulates the use of such medications with a delay:

Pharmaceuticals (Therapeutic Medications) Sleep Aids:

More on medication advice to medical examiners: Pharmaceuticals (Therapeutic Medications) - Do Not Issue - Do Not Fly.

Only the zaleplon molecule (a Z-drug ⁞ hypnotic) could be used in a practical manner (not publicly available in France nor likely in many other countries).

Circadian rhythm

What you are referring to has got the scientific name of circadian rhythm (circa = around, diēs = day), which is the subject of an article at SkyBrary: Circadian Rhythms. About the night flights:

  Night operations create a host of problems for flight crews. The
  primary problem is having to work efficiently and safely at a point in
  time when the work requirements are not in synchrony with circadian
  rhythms. Under worst-case conditions, crew members must perform
  demanding tasks during the early morning hours (2 am to 6 am) when
  their biological functions and performance efficiency are at their
  lowest level. This problem cannot be quickly solved by adaptation of
  the biological clock. Complete adjustment to night work requires at
  least 21 night shifts in a row with no days off. Adjustment of the
  biological clock does not even commence until about 10 days after a
  shift change.

Fatigue

Long article about Fatigue Countermeasures in Aviation, about zaleplon:

  This misalignment of the sleep/wake cycle and endogenous circadian
  rhythms could be the result of shift lag, jet lag, or attempting
  sleep at other than the habitual bedtime or at the second circadian
  dip in the afternoon. For such circumstances, the U.S. Air Force and
  Army have approved the limited use of temazepam, zolpidem, and
  zaleplon. These hypnotics can optimize the quality of crew
  rest in circumstances where sleep is possible, but difficult to
  obtain.

Inflight rest

As additional information about sleep management inflight: On a 8-hour flight, usually there will be 3 pilots, and each one will be able to sleep (outside the flight deck).

Air France Inflight rest for crews.
Air Canada When do pilots get to rest during long haul flights?
What Do Cabin Crews' Chillaxation Spots Look Like?


How is the phraseology of IFR clearances different between the US and Europe?

It's not only the IFR clearance, in Europe (where ICAO regulations are used everywhere) the phraseology is very different to the one in the US.
In Europe the phraseology is clearer and easier to understand, in the US it's shorter, less formal but easy to misunderstand.

Some examples are:

  118.350
  FAA: one one eight point three five
  ICAO: one one eight decimal three five zero

  Holding over DKB:
  FAA: Hold over DKB to the west.
  ICAO: hold over DKB as published, FL90

To answer your specific question about the IFR clearance:
In America an IFR clearance would sound like this:

  American 590, Ft. Lauderdale clearance delivery, cleared to Atlanta Intl' Airport, ARKES1 departure, then as filed, climb via the SID, expect FL320 onezero minutes after departure. Departure frequency 126.05, squawk 5523.

According to ICAO (specifically german phraseology):

  American 590, Frankfurt Delivery, startup approved, cleared to Atlanta aerodrome via DKB8S departure route, flightplanned route, climb altitude 4000ft, squawk 1000

So to sum it up, what's different are the parts "flightplanned route", "climb via the SID", and the departure frequency. If it comes to vectored departures it gets even more different, as in the US the clearance just states "via radar vectors" whereas in Europe the whole vectored departure procedure is inside the clearance ("... via vectored departure, after departure runway 18 climb altitude 4000ft on runway track, passing 3300ft proceed direct DKB, flightplanned route, ...").


What are the equations of motions for parafoils?

I don't want to sink in rigid body physics and it will be comfortable for me to stay on next level of abstraction.

Then I'm afraid you will stay stuck at your current level.

Your first equation is only a coordinate transform for the airspeed vector.

The reference area is just an arbitrary area. It makes sense to use the same area for all force components, and the wing area has been universally agreed for this. You will note that c$_D$ is quite a bit smaller than c$_L$ - why should the area be different?

When the same area and speed is used, you can calculate with coefficients just as if they were the real forces. This makes comparison between different speeds and different aircraft (or parafoils) much easier.

Regarding the effect of pulling on the risers (yes, that's the proper word): This changes both the load distribution and the local shape of the parafoil and is not easily expressed in a simple equation.


How can pilots fly VFR over-the-top in overcast conditions?

Perhaps the most important rule for a VFR pilot is "see and avoid" -- be able to see any immediate dangers (other aircraft, buildings, ground) and avoid them. When flying above the clouds, you can certainly see other aircraft and avoid them (as long as you're maintaining required cloud clearances), and the same for buildings. You cannot see the ground but on the presumption that your altitude is well above the ground and not significantly changing, this is not a factor.

As long as you're able to see the horizon, you're unlikely to become disoriented to the point of not actually knowing that the aircraft is or isn't flying straight and level. (Contrast that with flying in the clouds, where it's easy to become spatially disoriented and not be aware that you're starting to dive.) Limitations are basic: it's the PIC's responsibility to follow the regulations.

As to heading in the right direction and navigation in general, VFR flight does not mean one cannot rely on radio aids to navigation. VOR and GPS certainly make navigation very possible while on top, but to get to your question of "can it be done safely?" -- I suppose this comes down to a question of how reliable are your electronics and where are the weak spots; is the pilot under flight following or otherwise in contact with ATC, etc. If one were on top and were to lose the electrical system, there's certainly an emergency to be declared. If already in contact with ATC, it's an emergency that can likely be managed with the utmost of safety.


is there difference b/w moving object in a fluid and static object in a moving fluid?

That's called Galilean invariance. There's no difference whatsoever between a steadily moving object in a stationary fluid, and a stationary object in a steadily moving fluid.

You seem to be thinking that in a wind tunnel, some air will always get trapped downstream of (that is, behind) the object; and that for an object flying outdoors, air will never get trapped behind (that is, downstream of) the object. Neither of those things is true.

I see that you're thinking about supersonic flight; you're saying that

it seems like if an object is flying supersonically, it will leave a vacuum in its wake, but
it also seems like if an object is stationary in a supersonic wind tunnel, it will not have a vacuum in its wake.

I actually agree with your intuition here; I also think it seems like these two things will happen.

But when my intuition contradicts a law of physics, it doesn't mean that the law of physics is wrong; it means that my intuition is wrong.


Are there any Boeing 747 still flying for commercial use?

Quite a few, actually.

British Airways is the largest operator of B747-400 and flies a number of routes:

  Where does the Boeing 747-400 fly?

  The aircraft operates on a variety of routes, including:

  Beijing  Boston Cape Town Dubai Lagos

  Las Vegas Mexico Miami New York (JFK)

  Phoenix San Francisco Toronto

Air China operates both 747-400s and 747-8s

KLM does so but is phasing the 747-400 out

Korean Air, Lufthansa, Thai Airways, Virgin, El Al, Saudia operate 747s, among others.

Wikipedia lists 489 747s in service as of July 2017 though around half of them are cargo and the numbers would have reduced still further by now.

The latest data that I could lay my hands on lists the following airlines (less than twenty, sadly):

  Air China
  Air India
  Asiana Airlines
  Atlas Air
  British Airways
  China Airlines
  Corsair
  El Al
  Iraqi Airways
  KLM Royal Dutch Airlines
  Korean Air
  Lufthansa
  Mahan Air
  Qantas
  Rossiya Airlines
  Thai Airways
  Virgin Atlantic
  Wamos Air


How do I follow an ILS glideslope on the ADI in Falcon BMS?

The trick to flying a raw-data ILS is to find the pitch attitude that gives you the descent rate that achieves the target glide slope as far out as possible, then hold the attitude as you monitor the ADI, making small attitude changes and waiting for the result when corrections are required.

So try this procedure:

As the ADI comes alive in level flight, gradually lower the nose as the indicator approaches the middle index to an attitude that is giving about 6-700 fpm down The required descent rate depends on ground speed - a shallow glide slope like that going 130-140 kt will be somewhere around that descent rate; finding it by trial and error is easy enough (a normal 3 degree glideslope, which you are probably really referring to, will need about 750-800 fpm going that speed).  Note the pitch attitude in degrees and hold the attitude.
Monitor the ADI.  You want it to be very slowly creeping toward the target. If it stops above the target index or starts rising, you are descending a bit too fast.  Raise the nose 1 degree on the pitch index, hold the new attitude and wait. Vice versa if the opposite problem.  If it keeps moving the wrong way, change the pitch another degree and wait.
When the ADI is on the target, pitch a degree to stop it from moving, and wait.
At some point with these little tweaks you will find yourself on slope with the ADI not moving.  Note the pitch attitude and concentrate on holding that pitch attitude.
If the ADI starts to drift up or down, same deal, pitch up or down one degree and wait. If that's not enough, pitch another degree and wait.  And so on.  The key thing is to keep the corrections small and be patient.

As you get farther down the ILS the sensitivity goes up and the deviations become harder to track so it becomes critical to get sorted out as far out as possible and have the pitch attitude nailed as you get close in.  If you have the pitch angle and hold it the slope will generally take care of itself unless you encounter a change in wind that affects your ground speed.

The other thing is trim trim trim.  When you are on-target and on-speed, trim to hands off. Now only slight pressures are required to make corrections, and the "default" or relaxed, control input is the nominal correct one.


How to pick a good airfoil based on Cl and Cd

The $\alpha$=0 point on the polar would be a poor metric - there is nothing special about it, and your aircraft will not fly at this polar point when you strive for longest endurance. But your common sense is correct in predicting that this will be a slow airplane.

The precise answer normally depends on your means of propulsion. Since this is for gliders, the answer will be quite simple.

Your definition of efficiency is minimum energy loss. Energy means potential energy in this case $E_{pot} = m\cdot g\cdot h$, and the loss of potential $\frac{dh}{dt}$ energy over time is expressed as the sink speed $v_s$. So we need to find the polar point at which the glider will have the lowest possible sink speed.

Let's start with the parabolic drag equation which splits the total drag coefficient $c_D$ in one component which is constant over the lift coefficient range and one which changes with the square of the lift coefficient.
$$c_D = c_{D0}+\frac{c_L^2}{\pi\cdot AR\cdot\epsilon}$$
 The symbols are:
$\kern{5mm} m\:\:\:\:$ aircraft mass
$\kern{5mm} g\:\:\:\:\;$ gravitational acceleration
$\kern{5mm} \rho\:\:\:\:\:$ air density
$\kern{5mm} v\:\:\:\:\:$ velocity
$\kern{5mm} v_z\:\:\;$ sink speed
$\kern{5mm} c_{D0} \:$  zero-lift drag coefficient
$\kern{5mm} c_L \:\:\:$  lift coefficient
$\kern{5mm} \pi \:\:\:\:\:$  3.14159$\dots$
$\kern{5mm} AR \:\:$  aspect ratio of the wing
$\kern{5mm} \epsilon \:\:\:\:\:\:$  the wing's Oswald factor
$\kern{5mm} S \:\:\:\:\:$  wing area

Next, we need an expression for the sink speed. This should be easy: It is the forward speed times the tangent of the glide path angle $\gamma$. If you allow to approximate the tangent function for small angles by the radian of the angle, you can write:
$$v_z = v\cdot tan\gamma ≈ v\cdot\gamma = v\cdot\frac{c_D}{c_L}$$

Now insert the drag coefficient
$$v_z = v\cdot\left(\frac{c_{D0}}{c_L} + \frac{c_L}{\pi\cdot AR\cdot\epsilon}\right)$$

and make the speed dependency of the lift coefficient obvious:
$$v_z = \frac{c_{D0}\cdot\frac{\rho\cdot v^3}{2}\cdot S}{m\cdot g} + \frac{m\cdot g}{\pi\cdot AR\cdot\epsilon\cdot\frac{\rho\cdot v}{2}\cdot S} = v^3\cdot\frac{c_{D0}\cdot\rho\cdot S}{2\cdot m\cdot g} + \frac{1}{v}\cdot\frac{2\cdot m\cdot g}{\pi\cdot AR\cdot\epsilon\cdot\rho\cdot S}$$

Now we are ready to differentiate with respect to $v$ and find the condition when the derivation will become zero.
$$\frac{dv_z}{dv} = 3\cdot v^2\cdot\frac{c_{D0}\cdot\rho\cdot S}{2\cdot m\cdot g} - \frac{1}{2\cdot v^2}\cdot\frac{2\cdot m\cdot g}{\pi\cdot AR\cdot\epsilon\cdot\rho\cdot S}$$

Now re-insert the lift coefficient, which simplifies the equation mightily:
$$\frac{dv_z}{dv} = 3\cdot\frac{c_{D0}}{c_L} - \frac{c_L}{\pi\cdot AR\cdot\epsilon}\,\overset{!}{=}\, 0$$
$$\Rightarrow 3\cdot c_{D0} = \frac{c^2_L}{\pi\cdot AR\cdot\epsilon}$$

So your energy loss will be minimized when the induced drag is three times bigger than the zero-lift drag. The polar point is then:
$$c_L = \sqrt{3\cdot c_{D0}\cdot \pi\cdot AR\cdot\epsilon}\;\;\text{and}\;\;c_D = 4\cdot c_{D0}$$
With wings of a high aspect ratio this gives a rather high lift coefficient, so you might need to pick a high-lift airfoil in order to actually trim this polar point. The figure of merit when selecting the airfoil should be the ratio $\frac{c^{³⁄₂}_L}{c_D}$; this should reach its maximum at the lift coefficient of minimum energy loss. Enter the lift and drag coefficients into a spreadsheet and create a new column for $\frac{c^{³⁄₂}_L}{c_D}$ (or $\frac{c^3_L}{c_D^2}$; doesn't matter). Select an airfoil that maximises this value at the calculated optimum lift coefficient.


Why does Boeing name its aircraft B7x7 and Airbus names theirs A3x0?

Airbus started with the A300, which as usernumber commented was a 300-seat airliner design. So A for Airbus, and 300 for the number of seats. An A250 was also considered (guess how many seats), which became the A300B. The models counted up by 10 from there.

Boeing model numbers historically counted up, including the Model 40, Model 80, Model 247, Model 307 Stratoliner and Model 377 Stratocruiser. At the dawn of the jet age, they decided to change up their numbering scheme:

  To support this diversification strategy, the engineering department divided the model numbers into blocks of 100 for each of the new product areas: 300s and 400s continued to represent aircraft, 500s would be used on turbine engines, 600s for rockets and missiles and 700s were set aside for jet transport aircraft.

The 707 prototype was called the 367-80, or "Dash 80." When the time came to give it an official number they knew it was going to be a "Jet Transport" and would get a 700-series number, and they decided "707" had a better sound to it than "700". They kept the 7's and have counted up from there (not entirely in order).


Is a smartphone required to control a DJI Phantom 2 Vision+?

I'm pretty sure it works without the smart phone. If I understand correctly, the smart phone app simply relays the imagery from the camera, which can be useful for navigating especially if you do not have a clear line of sight.

Ars Technica ran a piece on this very model, which might interest you.


Why does linear airfoil theory break down at hypersonic speeds?

The linear theory makes certain assumptions in its formulation:

The flow is irrotational and isentropic.
The perturbations are small; i.e. the bodies are small at small angles of attack.

However, hypersonic flow violates these assumptions:

For a body in hypersonic flow (blunt body with detached bow shock), an entropy gradient is developed that varies along the distance of the body. It results in an entropy layer that persists all along the body.
In a hypersonic flow, the viscous boundary layer interacts with the shock and entropy layer and the kinetic energy of the flow is dissipated by the effect of friction within the boundary layer. Due to these viscous effects, the flow is no longer irrotational.

Note that the linear theory is not applicable if the flow is considered hypersonic. M > 5 is usually taken as hypersonic. Linear theory is not applicable in transonic regime either.


Why do airplane indicators start at 12 (o'clock), unlike cars that start at 7?

Most old-style indicators (RPM, cyl. head temperature, outside air temperature, oil pressure, etc.) are geared in such a way as to present their full operating range over a needle swing of 270 degrees. It is also common for the gauge mechanism to be oriented in such a manner as to put the nominal operating point somewhere near the middle of the needle's swing arc, where the gauge mechanism introduces the fewest errors in the reading.
Early (crude!) altimeters were also 270 degree swing gauges (i.e., barometers), but this made it impossible for the pilot to read that gauge to an accuracy better than perhaps 500 feet- which is insufficient for modern use. Later versions of the altimeter had gear trains inside them to magnify the needle movement enough to read the gauge to an accuracy of ~50 feet, but this in turn dictated that the gauge range cover multiple revolutions of the needle around the face of the instrument... like a clock.
Since we are all used to reading clocks that start at the "12:00" position, the multi-turn altimeters were set to start at 12:00 too and geared so one full needle revolution corresponded to one thousand feet on the "minute" needle, and ten thousand feet on the "hour" needle. This worked fine for small planes that rarely flew higher than 10,000 feet.
Registering multiples of 10,000 could be done with a third needle but a three-needle gauge isn't the easiest thing in the world to quickly scan. A better solution is to have a window cut into the gauge face behind which altitudes greater than 10,000 feet are displayed as numbers instead.
As an aside, in older American-made car speedos (1960's-era), 60 mph was most commonly positioned at the 50% scale point ("straight up" on the dial face) to give the driver a quick visual indication of 60, without having to read the numbers. When the US federal maximum speed limit was reduced to 55 during the oil crisis of the mid-1970's, 55 was then positioned at the straight up spot.


Declaring an emergency: How should you report fuel remaining?

There is no standard because there's no standard emergency. The response to "Say fuel onboard" (or the way the question is phrased) depends on who cares most about the answer.

Fuel Remaining (in minutes)
This is how you report it when you declare a minimum fuel emergency, and it's most useful for approach and tower controllers to know exactly how long they have to get you on the ground before your engine gets quiet (and if they can get you to an airport in that timeframe).
Fuel Remaining (in hours)
This is what you'll give for most general emergencies, and also what's entered on flight plans. It's the most generally useful number to a pilot or controller.
If you're VFR-only pilot stuck on top of an overcast and call ATC with a pan (urgency) message because can't see a way through the controller will want to know how far they can vector you to find a hole before it becomes a fuel emergency too.
Fuel Onboard (in Pounds/Kilograms or Gallons/Liters)
The folks who care about this number drive around in ugly fire trucks wearing silver jumpsuits (the ARFF crews): If the worst happens they want to know how big a fire they might have to deal with, and how much foam they're going to need to handle it.


Can you identify this unusual plane by its description?

Sounds like it may have been a Boeing RC-135

(source)

No windows and a flat grey color would lend to either a cargo aircraft or a military aircraft with military being likely considering the color choice.


How do pilots stay disciplined and use checklists, even after they have become routine?

You stay vigilant by having seen things go wrong.

Like Jamiec mentioned the importance of a proper preflight is drilled into you by your primary instructor from day one in light aircraft, and that mentality carries through all the way up to heavy transport-category aircraft: You want to find any problems you can while you're on the ground, because if you take a problem into the air with you it's a decision you can quickly come to regret.

Personally I've found all sorts of "interesting" things on preflight inspections of light aircraft, including (but not limited to):

Mud wasps building a nest in the pitot tube
Mud wasps building a nest in the fuel drain
(still don't know what was up with that)
Missing screws from a fairing
Flat-spot on a tire
A tennis ball stuffed in between two cylinders
(a common flight instructor trick to see if students are doing a thorough preflight)
Position light lenses installed backwards
(another common CFI trick, but this one was actually a maintenance shop screw-up)
Various light bulbs burned out
Water in the fuel after a heavy storm.

I've also heard some scary stories:

Migrating colony of bees hanging out on the tail of the aircraft
(described as "The tail was literally dripping bees")
Flight controls rigged backwards
Big gouge in the wingtip
(acquired by the previous pilot scraping the tip against another plane's tail taxiing in on the ramp)
The ever-classic "ran out of fuel because you didn't visually check the tanks"


Can rotorcraft pick up a dangerous electric charge?

In the same way than an aircraft will build static charge on the wings from friction with the air, the same thing can happen with helicopters from fast moving blades.
From a 1962 US Army document:

Any aircraft flying in the atmosphere can be considered as a conductive body located in a highly electrically insulated environment. In such a body, electrostatic charge is generated by three principal mechanisms:

Charge transfer created by a triboelectric effect between the aircraft and the atmospheric particles, such as dust, water, water vapor, snow, etc.
Unbalance of the ionic content of the exhaust gases produced by the aircraft engine(s).
Induction charge due to high electrostatic
field gradients which are found occasionally in the aircraft flight path.

Source

Here's a more detailed photo of the US army discharging a helicopter while wearing insulating gloves:

 SGT Nathan Rodeheaven uses a static probe to discharge static electricity from a UH-60 Black Hawk before his teammate, PV2 Danny Browning, hooks up the cargo to the helicopter. The safety measure prevents the hook-up man from being electrocuted in the event there is accumulated static electricity. Photo: Kristin Molinaro


How can one quickly estimate interference drag for a configuration?

Use Sighard Hoerner's Fluid Dynamic Drag. It lists tons of wind tunnel and flight test data for a wide variety of configurations and flight regimes.

Interference drag has several sources:

Flow separation due to the coincidence of the pressure rises of two bodies. Each of them by itself would show attached flow, but in the vicinity of a similar body with its own pressure rise, the flow separates. This is most pronounced at low speed.
Addition of the accelerated flow of two bodies in transsonic flight. While each of the single bodies has no supersonic pocket around it, both in combination will cause a local supersonic area with a subsequent shock.
Disturbance in the spanwise lift distribution, such as wings interrupted by the fuselage or engine nacelles.

Look for areas where one of these conditions is fulfilled, and then try to find a similar case in Horner's book to estimate its severity. Note that all interference drag varies with speed and angle of attack. Doing so carefully will bring you within 10% of the real drag, but needs some experience.

In the end, drag estimation is like bookkeeping. You need to carefully add each component and make sure to avoid double-counting or mixing up reference areas. Sorry, but if you want a good result there are no shortcuts.


Is takeoff permitted from an aerodrome inside a CTR when it's outside the tower's operating hours?

In the United States, if you are VFR at an airport in Class G or E airspace, you may take off without needing clearance or permission from ATC.
Normally Class D airspace reverts to E or G outside of tower operating hours, therefore no communication with tower is required or even possible.


Why is there a plateau in helicopter H/V diagrams?

As speed increases, most helicopters pitch up.  This is because the lift generated on the side of the retreating blade gets progressively less than the lift generated on the advancing blade side.

Due to precession, the effect of this is felt 90 degrees later so instead of rolling to the left (or right, depending on which way the blades rotate) because of the dissymmetry of lift, the tail drops, therefore pitching the nose up.  Whether this happens on a particular helicopter, and by how much, depends largely on the pitch stabilisers.  However, helicopters are naturally unstable in pitch.  You cannot take your hand of the  cyclic and maintain a constant attitude, absent any autopilot or other automatic assistance.

As the helicopter accelerates, the pilot subconciously counteracts this by applying foward cyclic pressure.  The higher the speed, the more forward pressure is needed to maintain altitude and the helicopter flies nose down.  You fly a helicopter by "sight picture" to such an extent, that to accelerate, you pitch the nose down to give you the "65 kt picture", or the "100 kt picture", allow the aircraft to accelerate to the desired speed, then trim.  The nose is pitched down a lot at 100 kts compared to say 50.

When the engine quits, assuming it's an instantaneous failure, there is nothing to stop that forward pressure forcing the nose down and at such low heights and high speed, losing 18 feet of height before the pilot reacts and pulls back to flare would be easy.  Even if they react really quickly and flare without losing much more than 5 or 10 feet, there is a very real risk that the tail will strike the ground and at those high speeds, that will result in a really bad crash.

Let's assume that everything goes right. There is no time at that height to lower the collective and raise it again.  You will also have a lot less than a second to flare so will lose very little forward speed.  In the best case, you are going to land at 50 kts or higher with the collective in your armpit and the rotors already stalled, if not stopped altogether, and this is at best a bad crash, quite possibly fatal.

The most important thing to remember is that the shaded areas represent the flight regimes where test pilots, with instant reactions since they initiate the manoeuvre, cannot demonstrate a safe landing with no damage.  This is at the edges of the shaded areas and once they get to the point of saying "one more foot, and we would not have had a successful landing", they stop exploring the envelope and draw the curve in the POH.  To add a safety margin, the tests are done at max weight.  Even so, the wise pilot will give those areas a wide berth whenever possible.

Why isn't there some automatic device to pull the cyclic back?  Because you do not do this if the engine quits when in a hover or up to about 10 kts at low height.  In the avoid area you ask about, it would need to pull, then push to level the skids again in the blink of an eye.  It's different when hovering at 1,000 ft and different again if doing 90 kts at 1,000 ft. And that's before we add all the variables - pressure altitude, temperature, wind strength and direction.

To deal with all of this, you would need a very clever system loaded with sensors.  Most people call such systems "pilots".

I would rather just avoid the shaded areas.  It's no big deal.


Does the person directing the plane to parking not risk getting ingested by a jet engine?

A marshal should always ensure that he is in the line-of-sight of the pilot, failing to do so will effectively mean that the pilot is losing its extra sets of eyes. It is unable to see the hand gestures of the marshal guiding him into a parking spot.
To be visible for a modern jet liner pilot, you have to be meters in front of the nose of the aircraft. In the picture below, you have to be roughly on the right side of the orange line to be visible to the pilot. Modern airports use a digital marshal on a screen mounted to the terminal building.

Incidents of people getting sucked into the engine mostly happen due to miscommunication. Someone already walking up to the rear wheels with the blocks while the pilot spins up the engines to move the plane a little bit forward.


How are the limits of the center of gravity chart established?

These "bends" (or sloped straight lines) are due to various structural constrains on the aircraft.

In level flight, the sum of forces must be zero:

LiftWing - Weight - LiftTail = 0

The summation of moment should also be zero, otherwise the plane will pitch up or down.

The wing has a structural limitation, i.e. a maximum loading. Solving the above equations for constant LiftWing yields a slopped straight line. This is the "bend" portion you see in the graph.

Drawing these lines (shown as colored lines here) on top of a weight and balance graph yields:

The resulted graph is the intersection of the various constraints.

In the C-182 graph, there are five constraints (five edges). Wing loading and tail loading is used as an example here, since I do not know what is the actual constraint used by the engineers. Another possibility is strength of the nose gear.

Main landing gear loading and aft tipping limit would have resulted in a downward slope, which does not correspond to the given graph.

Source: Center of Gravity Limitations (PDF)


Should I have carb heat on for landing in a C152?

The approach and landing phase are the times when carburetor icing is MOST likely to occur.

Once a carburetor has ice, it may take a period of time for full application of carburetor heat to clear any ice.  Furthermore it is possible to have enough ice accumulation that application of full throttle and carburetor heat would be insufficient to melt carburetor ice, and little or no additional power would be available at go-around.

So in short, not applying carburetor heat puts you at unacceptable risk of loss of power in the event of a go-around, and potentially even in the event of the need for additional power to compensate for wind shear on approach and for glide path adjustments.

Having examined the risks of no-carb-heat on approach, we should look at the secondary consequences. The operation is contrary to the POH, and the POH is the manufacturer's best guidance for the safe operation of the plane. The practice of asking yourself, "What would the accident review board have to say about this?" is a healthy tool for evaluating decisions. To deviate from the POH, and from conventional wisdom and practice in a critical phase, where there is little recovery time, presents an unreasonable risk on your flights, and is scarcely defensible.  Without an articulable and compelling argument as to why EVERY time you make an approach and landing, the carburetor heat should be off, you are hard pressed to justify a deviation from the manufacturer's guidance.

Ok let's go to an extreme, and say that you are landing in high winds at a desert strip with blowing sand across the runway.  In a situation like that, and experienced private pilot might elect to turn off carb heat just prior to landing to prevent unfiltered air with sand from being ingested into the engine. On the other hand, if the wind is blowing that hard, the possibility of a missed approach and go-around is even higher.

There are circumstances when carb heat may be left off on an approach.  If the aircraft is equipped with a carb temp gauge, and the carb temp has been verified to be above 32F, then it is commonly considered acceptable to avoid carb heat.  Some planes equipped like that will also have a warning alert to announce temperatures which are conducive to carburetor icing. That alert is often coupled with an ice detector sensor in the carburetor. Likely your 152 has neither a carburetor temperature gauge, nor a carburetor ice annunciator.

Let's also talk training risks, since you are a student pilot. Your operations for some time will be as a single pilot, and your procedures should be designed to minimize risk. One way to accomplish that is to simplify your procedures so that they can be accomplished by rote. Having the same procedure each time, without the need to collect data and make evaluations, helps simplify your piloting chores. You are not flying complex aircraft with complex pilot chores, and you do not have the benefit of a second crewmember to make observations and read you checklists.

Most CFIs, DPEs (pilot examiners) and FAA Operations Inspectors, will expect that you follow the POH and the manufacturer's checklist and procedures. In the case of the 152, that will be to turn on carburetor heat prior to the reduction of power (in the pattern).  On balked approach, the procedure is to apply full throttle, and at most altitudes, verify mixture rich, and then remove carb heat. If the removal of carb heat causes a reduction in power (or RPMS) then carb heat is to be reapplied.

There may be other aircraft with different procedures, but you are not flying them. You are flying a 152, and it would be best practice and a defensible position to fly in accordance with the manufacturer's published procedures.

If you were taking your private pilot check ride with me, and you failed to apply carburetor heat in a C152 lacking a carburetor temperature gauge and/or ice sensor, you would not pass the check ride.

Finally, let me just add a story...on a crisp fall day, without exceptional humidity, a student/instructor were flying in the pattern doing touch and gos. The airport was surrounded on all sides by quarry, with a road leading to the flight school. That road also had the power lines to operate the stone handling and crushing quarry equipment. The plane was a new C152, the first year that they were available. It was later found that the cable had slipped in coupler on the valve for carb heat.  You know where this is going. The student was mis-aligned on her approach, and when she applied full throttle for a balked approach, insufficient power was available to establish a climb. The instructor took over, and had to weave the wings between 13.2kV three-phase power lines on each side of the road, to land the plane on the road to the flight school.

Why adopt practices which will unnecessarily test your exceptional flying skills?


What would happen if flaps are extended beyond 40 degrees?

Depends on the kinda of flaps installed on the aircraft; in the example above with fowler flaps, the design would begin to just create excessive drag without gainful lift and would require a pretty bulky structure to accommodate for the aerodynamic loads imposed upon them.

Now some other types of flaps like the split flaps or dive brakes like those found on the Spitfire fighter were designed to extend 90°.


What is the difference between the Flight Control Systems of different F16 models?

The  main difference  is  processing speed, with the digital FCC's being faster than the analog models ( the analog-equiped aircraft it takes their FCC longer to detect the over-G, determine a correction, and send the correction to the actuators)and that's why first blocks until the 40 blocks will show +9G in the HUD .


What is the correct phraseology to request a climb?

I would say that “Request climb FL350” is better.

I never use the word “to” in altitude requests as it can be confused with “”two” as in “request climb to seven thousand” (request climb two seven thousand)

If you get in the habit of using “to” with flight levels, you will probably use it in a baro altitude request as well.

I also leave out “climb” and just say “request FL350”. But, when ATC says “climb FL350”, I will read back “climb FL350”.


When would these two fixes at KMEM be used?

Those are part of the Basic T of the Terminal Arrival Area (TAA).

  The basic design of the RNAV procedure
  underlying the TAA is normally the “T” design (also
  called the “Basic T”). The “T” design incorporates
  two IAFs plus a dual purpose IF/IAF that functions as
  both an intermediate fix and an initial approach fix.
  The T configuration continues from the IF/IAF to the
  final approach fix (FAF) and then to the missed
  approach point (MAP). The two base leg IAFs are
  typically aligned in a straight-line perpendicular to
  the intermediate course connecting at the IF/IAF...

  – AIM 5-4-8

They're used in vectoring. Depending on where the aircraft is coming from, it'll be directed to the dual purpose IF/IAF or one of the flanking IAF's. According to the AIM they're not used when traffic levels are high. They can be used with or without a STAR, either way they reduce the workload.

  TAAs are primarily used on RNAV
  approaches but may be used on an ILS approach when
  RNAV is the sole means for navigation to the IF;
  however, they are not normally used in areas of heavy
  concentration of air traffic.

Follows is a brief description of TAA's. (Linked article is also informative.)

  TAA effectively replace feeder routes, and they enable ATC to issue succinct, efficient clearances to RNAV-capable aircraft flying along an airway that passes over or near an airport or proceeding direct toward an airport from any direction. Using TAA eliminates the need for a series of vectors, which also makes them useful in areas where ATC may have poor radar coverage at the altitudes typically needed to guide airplanes onto feeder routes or the final approach course.

  – bruceair.wordpress.com


Would a 2nd row of distributed props on a 2nd staggered wing of a biplane increase its efficiency?

Source: nap.edu

Not really no. The velocity off a propeller does not shoot straight back, rather in circular motion (shown above and below).

Source: High-Lift Propeller System Configuration Selection for NASA's SCEPTOR Distributed Electric Propulsion Flight Demonstrator, NASA

From the conclusion of that NASA report on span-wise propellers generating lift:

  A potential constraint on the design of the high-lift propellers system is the total thrust. If large amounts of lift augmentation are required from the propellers, then high thrust values from the high-lift propellers are likely. If these propellers produce excess thrust, then the aircraft will be unable to sustain flight at the desired speed. This implies that drag producing devices may need to be added to the aircraft or the primary propellers operated as windmills to produce additional drag.

Applying the same conclusion to the biplane, thrust will be wasted, and possibly will work only in a limited angle-of-attack range for the prop-boosting-prop-boosting-wing idea.

Own work; variable pitch blade

Note that a very fast stream before a propeller leads to [forward] thrust losses due to the propeller's angle-of-attack (shown above). And the less efficient the thrust becomes, since the momentum change will be harder – propellers add little velocity to large amounts of air, in fact, the pressure rise (a thrust measurement, which also is indicative of the mass flow) is around only 2% for propellers.


Which books should I study to understand more about Supercritical airfoils?

Introduction to Transonic Aerodynamics

Roelof Vos, Saeed Farokhi (more)

  Written to teach students the nature of transonic flow and its
  mathematical foundation, this book offers a much-needed introduction
  to transonic aerodynamics. The authors present a quantitative and
  qualitative assessment of subsonic, supersonic and transonic flow
  around bodies in two and three dimensions. The book reviews the
  governing equations and explores their applications and limitations as
  employed in modeling and computational fluid dynamics.

Transonic Aerodynamics of Airfoils and Wings

W.H. Mason (more)

  Professor emeritus by the Virginia Tech, expert in aerospace
  engineering who worked at Grumman Aerospace where he served in the
  structural mechanics section and later in aerodynamics and worked on a
  number of high-profile projects, including the Grumman X-29. Has
  taught classes — including his "famous" Configuration Aerodynamics
  course.

Review of NASA Supercritical Airfoils

Richard T. Whitcomb (more)

  NASA supercritical airfoils are characterized by a substantially
  reduced curvature of the midcord region of the upper surface together
  with increased camber near the trailing edge. The basic aerodynamic
  phenomena associated with the airfoils and representative wind tunnel
  results are discussed. The results indicate that the drag rise Mach
  numbers for NASA supercritical airfoils are 0.1 higher than for
  comparable NACA 6-series airfoils. A recent analytic method for
  predicting the aerodynamic characteristics of supercritical airfoils
  is described. The flight demonstration programs of three applications
  of supercritical airfoils utilizing the F-8, T-2C and F-111 as test
  beds are summarized.

Richard T. Whitcomb on Wikipedia.

NASA Supercritical Airfoils, A Matrix of Family-Related Airfoils

Charles D. Harris (more)

  The NASA supercritical airfoil development program is summarized in a
  chronological fashion. Some of the airfoil design guidelines are
  discussed, and coordinates of a matrix of family related supercritical
  airfoils ranging from thicknesses of 2 to 18 percent and over a design
  lift coefficient range from 0 to 1.0 are presented.

Supercritical Airfoil Design for Future HALE Concepts

Kasim Biber, Carl P. Tilmann (more)

  This paper presents design and analysis of a new airfoil for future
  High-Altitude Long-Endurance (HALE) aircraft that has an operational
  condition at supercritical speeds. The XFOIL and MSES computational
  codes were used to design, modify and analyze the airfoil.

Design of Laminar Supercritical Airfoils Based on Navier-Stokes Equations

Zhong-Hua HAN, Jie DENG, Jun LIU,  Ke-Shi, ZHANG, Wen-Ping SONG (more)

  This paper aims to develop a suit of design methods and
  tools for laminar supercritical airfoils, based on
  high-fidelity computational fluid dynamics (CFD). The reliable
  transition perdition method, efficient inverse design and
  global optimization design methods are regarded as
  three key issues, which are addressed in this paper. The automatic
  transition prediction method coupling Navier-Stokes equations
  flow solver and eN linear
  stability analysis method is applied to the design and analysis of the
  laminar supercritical airfoils; inverse design and optimization design
  methods based on kriging surrogate model is developed to
  attain favorable pressure gradient while reducing wave
  drag; efficient optimization based on kriging model and an
  improved EI (expected improvement) method is developed for finding
  the global optimum.

NASA Technical Memorandum 103933 An Experimental Investigation of a Supercritical Airfoil at Transonic Speeds

George G. Mateer, H. Lee Seegmiller, Lawrence A. Hand and Joachim Szodruch (more)

  Benchmark experimental data obtained in the two-dimensional, transonic
  flow field surrounding a supercritical airfoil are presented. Airfoil
  surface and tunnel wall pressure and LDV measurements are used to
  describe the flow on the model, above the wing and in the wake.
  Comparisons are made with calculations using the Reynolds-averaged
  Navier-Stokes equations. The results illustrate the performance of two
  turbulence models in both separated and attached flows. The largest
  differences between theory and experiment occurred in separated flows
  with the Johnson and King turbulence model providing the best
  estimates.

Analysis of Aerodynamic Characteristics of a Supercritical Airfoil for Low Speed Aircraft

P.Sethunathan, M.Niventhran, V.Siva, R.Sadhan Kumar (more)

  The main goal of the proposed paper is the analysis of aerodynamic
  characteristics of an various supercritical airfoils like 0406, 0412,
  0706 and 1006 influence on the  dramatic improvement in lift and
  reduction of drag in low speed aircraft. In a precedent work,  a  cusp
  like  structure  at  the  trailing  edge  of  an  unsymmetrical
  airfoil  produces a  very  high  improvement  in  climbing performance
  of an aircraft.

Two-dimensional Wind-tunnel Tests of a NASA Supercritical Airfoil with Various High-lift Systems

E. Omar et Al. (more)

  Three high lift systems for a 9.3 percent blunt based, supercritical
  airfoil were designed, fabricated, and wind tunnel tested. A method
  for calculating the viscous flow about two dimensional multicomponent
  airfoils was evaluated by comparing its predictions with test data. A
  comparison of high lift systems derived from supercritical airfoils
  with high lift systems derived from conventional airfoils is
  presented. The high lift systems for the supercritical airfoil were
  designed to achieve maximum lift and consisted of: (1) a single
  slotted flap, (2) a double slotted flap and a leading edge slat, and
  (3) a triple slotted flap and a leading edge slat.

Aerodynamic Characteristics of an 11-percent-thick Symmetrical Supercritical Airfoil at Mach Numbers Between 0.30 and 0.85

Blackwell, J. A., Jr. (more)

  Abstract: The aerodynamic characteristics of an 11 percent thick
  symmetrical supercritical airfoil were determined in an 8 foot
  transonic pressure tunnel over a Mach number range of 0.30 to 0.85.
  The Reynolds number of the tests, based on the airfoil chord, varied
  with Mach number over a range of 360 million to 774 million. The
  geometric angle of attack varied from -0.5 to 10.5 deg. The abrupt
  drag rise for the supercritical airfoil at zero normal force
  conditions occurs at a Mach number just above 0.82. The corresponding
  drag rise Mach number for a conventional NACA 0012 airfoil is
  approximately 0.70. At zero normal force conditions, the level of
  supervelocity over the supercritical airfoil is considerably reduced
  from that for the NACA 0012 airfoil. Also, the shock wave for the
  supercritical airfoil is substantially weaker than that for the NACA
  0012 airfoil.


What is the registration number of the 10,000th Airbus?

The answer you are looking for is: 9V-SMF.

Current registration number: 9V-SMF (source)

Let's try to add some related details.

Aircraft can have multiple ID during their life, at least a preliminary ID to be used by the manufacturer prior to delivery to the customer, and then at least a national registry ID.

Manufacturer pre-delivery ID

Airbus aircraft final assembly line for the A350 is in France at Blagnac, a small city near Toulouse, with parts coming from several countries. There are other final assembly lines, but none is for the A350.

The first test flights will therefore happen in France, well before delivery to the customer. The French registry delivers temporary IDs to Airbus, the same IDs being continuously reused on successive airframes. Airbus uses a lot of them.

In France temporary IDs start with letter W. This A350 has been registered F-WZFD until being delivered to Singapore Airlines:

The special 10,000th aircraft delivery logo on A350-900 MSN 54 with its temporary registration: F-WZFD (source)

This same number was previously used on other aircraft, e.g.this A350 c/n 9 and will be reused on next pre-production or pre-delivery aircraft.

Customer registration

Singapore Airlines then requested an ID which was delivered by the Singaporean registry. This ID is 9V-SMF:

This number was previously used for a B747 at Singapore Airlines.


What is the "departure cable" that tower mentions?

The "departure cable" refers to an arresting gear cable on the departure end of the runway, similar to the one used for landing on aircraft carriers. Airports that often have fighter jet traffic may have an arresting system installed near each end of the runway.

Fighter jets tend to take off and land at higher speeds than other aircraft, and don't have the same braking power that other jets do. The speed brakes may not provide substantial drag, and the engines typically do not have reverse thrust capability. Since there is more room on a runway than on an aircraft carrier, land-based systems take more distance to stop aircraft.

The system is not used for every landing, but is useful to have in certain situations. For normal landings or aborted takeoffs, the system on the departure end will be used to prevent a runway overrun. If an aircraft needs to make an emergency landing, it will use the system closest to the approach threshold. Some cable systems are able to retract into a recess in the runway when not in use, which prevents issues when aircraft roll over it.

When the system is deployed in normal use, the tower will advise aircraft that the departure end cable is up. The departing aircraft will generally be in the air by the time it reaches the cable, but in case of a late rotation or aborted takeoff, the pilots can anticipate running over the cable.

Arresting gear is indicated on the FAA airport diagram as follows:

Source

The cable is marked by 10-foot diameter yellow circles on the runway.

Source: Google Maps


Why are fighter jets equipped with dorsal fin?

There are two features that you may be referring to.

A) Is an antenna that is shaped to provide low drag. Not all F16 have this.

B) The true dorsal "fin":

increases structural strength
decreases drag by providing a fillet for the vertical stabilizer,
improves stability about the vertical axis,
and specifically in the case of the f16 (when installed)
     aerodynamically blends the drag chute pack (box at base of Rudder)
many aircraft use this as a convenient air intake for
     equipment or auxiliary cooling.

source


How is a stolen aircraft returned to its owner?

If the owner retains ownership (rather than an insurance company who paid out a claim on the loss), it's up to the owner. The owner can either go pick it up if it is airworthy, or arrange for someone to ferry it back to the owner's home airport.


Does the ditching switch allow an A320 to float indefinitely?

The answer is no, not totally, but it would really slow things down. I don't think anybody knows the precise answer because only flat water ditchings seem to result in the airplane stopping in the water in one piece (such as 1549 and a similar one in Malaysia) and flat water incidents (like Malaysia and some airport overruns) are usually in shallows where the ditching valve is moot.

But assuming an A320 was able to ditch on open ocean swells without breaking somewhere, certainly it would float for a much longer time, but not forever. Pressure hulls are never absolutely fluid tight; door/hatch seals leak a little bit, and there may be tiny leaks through various entry points below the water line like bleed air shutoff valves, fay-sealed skin laps, rivets, control cable pressure bulkhead fairleads, etc (the older the airframe the leakier).

Wing dry bays may be sealed off with a tape made for the purpose but they are not usually totally water tight.  Water can migrate into the fuel tanks through the vents.  Full fuel or nearly full fuel would be a bonus, fuel being buoyant.

You certainly would have a lot more time to get onto the rafts (perhaps Airbus has estimated the theoretical sink time by calculation), but it would sink eventually (it would take quite a few hours, maybe even a day or two), and you aren't going to be staying on board any longer than necessary regardless.

(Now, if you ditch in a composite foam sandwich sailplane, well you've got yourself an unsinkable boat right there, and if you took a paddle along, you could actually go places.  If I'm in a glider that gets low over rough forested terrain, and there are lakes around, I'm putting it in the water and paddling it to shore with whatever I have at hand).


Turbine Blade
The turbine blade (part number 1475M35P01) is from the High Pressure Turbine (HPT) a CFM56-3 according to this ATSB report on performance testing of the engine. The report contains several images of blades which look similar to your photos.

Compressor blade
A search on locatory.com for the part number (B778503) lists the description as C-3 suggesting it could be a Stage 3 compressor blade. This would fit with the high aspect ratio of your blade.


Can a surrendered type certificate be reacquired by the manufacturer or by another entity, or is it considered to be permanently lost?

From the FAA point of view, the TC is not lost but cannot be reissued. You have to get a new one if you want to become the new TC owner. Order 8110.120 states:

"The surrender of a certificate is a final action. Once surrendered, the action cannot be reversed. A certificate cannot be reissued to a third party or a former holder. A new TC for the product could only be issued as part of the full TC process with a new application, subject to all current regulations."

I don't know EASA's policy but I suspect it likely mirrors the FAA's.

In addition, your statement that aircraft covered by the surrendered TC are grounded is incorrect. Surrendering a TC does not affect the airworthiness status of aircraft produced under the TC. From the same document linked above:

"The surrender of a TC does not affect the airworthiness certificates of existing aircraft. The aircraft remain subject to future AD actions for safety of flight issues that could affect their airworthiness certificates."