How can pilot remember when or where to do tasks such as changing radio frequency and change fuel tank?

Make your own checklists

While the manufacturer provided check lists are a good starting point and generally cover the operation of the aircraft well the FAA does not forbid you from extending them. If you have a few more steps you feel are worthy of a checklist write up and print your own.

If you are switching tanks it sounds like you are flying a piper. Are you starting a time right before takeoff? If not you should be and you should always be changing tanks around the 30 minute mark. Another good rule of thumb with tank changes is to always execute them when near or overflying a field. Waiting an extra 5 minutes or switching 3 minutes early if their is a field below you is always a bit safer (should the engine cut out). Remember, for the pilot, a flight is not a journey from point A to point B it’s a series of maneuvers from one potential emergency landing spot to the next.

As a student pilot you are also still deloping habits which will be honed over time. You should debrief either with an instructor or do a self review after every flight. What went well what didn’t, what can be improved and how. The next time you get in the plane work these things and eventually you will build a good cockpit workflow.


Why aren't there more helicopter aerobatics at airshows?

First off: I'm not a pilot.

I believe there are two additional issues here:

There is no pilot in the RC helicopter. The forces exerted in some of those maneuvers look pretty extreme, I highly doubt even the most well-trained aerobatics pilot/astronaut/fighter jock would be conscious longer than about 2 minutes into the video you posted. I'm not even sure if they would be able to survive that.
Scale. All sorts of weird things happen when you scale complex systems up or down. (A famous example is the square-cube law: when you scale a structure up linearly, it's area scales as a square, and its volume (and thus weight) scales as a cube. So, an ant that is 100 times bigger will have feet that are 10000 times bigger but will have to support a weight that is 1000000 times bigger.) For example, the airframe of the RC helicopter is much stronger in relation to its size than it is on a real helicopter. Also, RC models (not just helicopters) are typically ridiculously overmotorized compared to their real-life counterparts.


Aeroelasticity is the elastic deformation of a structure caused by aerodynamic forces. An example is the flexing of a wing. The change of the shape of the structure has in turn an effect on the aerodynamics.

Aeroelastic effects can be static, such as the upward deflection of a wing under the influence of lift, or dynamic.

In the static case, the aerodynamic for cause the structure to deform. If the structure is very flexible this can cause a stability problem: the deformation causes an increases of the aerodynamic load, that will in turn increases the deformation until the structure fail.

In dynamic cases there is an interaction between the aerodynamic forces, the inertial forces and the deformation of the structure. Usually the dynamic behaviour is transient and damped.

When the dynamic behaviour is undamped (the aerodynamic forces add more energy than is dissipated in the transforming structure) an increasing vibration will occur. This is called flutter. Flutter is unwanted the because the resulting severe vibrations can cause structural damage.

Here is an example of flutter on a small aeroplane:


Are matches in checked baggage a safety problem?

The reason that matches are banned on most airlines is not that they might accidentally catch fire. Especially not in the cargohold of the plane. Sometimes the cargohold is not even pressurized. and a lot of safety measures are taken to prevent cargo fires, including suppression systems in case this does happen.

Most likely the ban is for carry-on baggage. Most airlines will allow you to take a lighter with you, but only 1.
The reason is that if someone wants to start a fire in the passenger cabin, this is not as easy with a lighter.
A box of matches on the other hand is a lot easier and faster to set on fire.


What's the difference between multiple disc brake and segmented rotor brakes?

More properly, both types are multiple-disc brakes. Disc brakes, in turn, can be either continuous or segmented.
Regular continuous disc brakes are somewhat similar to car disc brakes, except for the brake pads being replaced by an entire stator disc. The calipers can be placed in one spot, like on a car, or on larger planes spaced symmetrically around the disc, and the areas away from the calipers are only pressed against the rotor by the pressure plate's and the stators' rigidity.
Much of this action is lost as the discs heat up and expand, causing them to warp. When the discs are warped, only the closest part of the disc keeps making contact. The pressure is very inconsistent among the disc, governed by geometry; something will touch, but it's a few radial lines across the disc, not the whole.
Segmented disc brakes return to (semi-)individual brake pads, spaced around the disc evenly, with a caliper per each brake pad. Most importantly, the rotors are split into separate sectors (only loosely connected around the carrier), so they get room to expand in all directions.
When a segmented disc expands from the heat, the sectors almost touch, but without significant warping. And each brake pad is forced against the rotor by its own caliper (even though there's a pressure plate in between); they are less fixed geometry and more fixed pressure. The theoretical contact area is smaller overall, but it's maintained constant even as the brakes heat up. All of the brake pads keep creating friction against the rotors at all times.
I could probably sketch something up, but you can as well do an experiment - push two plates of any material firmly against each other with your hands and rotate them against one another. It won't be difficult to do, even if they're rough, because your hands aren't very rigid, not ensuring constant contact areas. Now place a few clothespins around their perimeter. You'll notice that they'll become much harder to turn against one another, even though the clothespins are weaker than your arms.
Regular disc or multi-disc brakes clamp only a small part of the disc, with rigidity somewhat helping elsewhere, like with two plates held in your hands. Segmented-disc brakes rely entirely on the latter effect, braking at multiple very firmly clamped areas across the disc stack. They provide strong braking torque even when very hot.


What are these red lights next to an airport runway?

These are VASI lights, which stands for Visual Approach Slope Indicator. When approaching a runway to land, an aircraft follows a specific glide slope. Usually, that slope is around -3 degrees.

These VASI-lights help the pilot visually verifying that they are not too low and not too high. There are a total of four lights, representing two bars.

Now you only see two reds on the VASI, but there is also another color, that you will never get to see, except if you sit in a cockpit of a plane: White. Using this two colors, the VASI tells pilots if they are approaching the runway too high or too low.

The VASI works analog, so it does not know how high a plane is and it's position and changes lights accordingly. Both red and white light at the same time and by using a lens-mechanism, the pilots gets to see the correct lights.

There are three color codes of a VASI:

Source

When both the VASI-bars are red, as in your picture, the plane is too low and needs to pitch up. Red and white means on glidepath and two whites mean too high and the pilot needs to descend faster.

There's also a mnemonic to remember the (very easy tbh) color codes:

  White over White, you're high as a kite.

  Red over White, you're alright.

  Red over Red, you're dead.

  White over Red, unsaid.

(White over red is no color code actually, because you would have to fly inverted to get it, that's why it's "unsaid".

Here's how a VASI-light looks close-up:

Source


How are credit cards processed during flight?

Presumably, they use an off-line transaction. The reason your credit card has raised numbers is that, in the old days, before ubiquitous data connections, a card transactions used a machine like this

to transfer an imprint of your card details onto a form, using carbon paper. You would then sign the form and the merchant would send it off to the bank to get paid. It wasn't possible to verify in advance that you had enough money in your account but the deal was that the bank would honour the transaction and then come after you with a big stick.  The point of my mentioning this is that, although we're now very used to the idea that the merchant talks to your bank while you make a card transaction, this wasn't the case even 20 years ago.

Today, it's still possible to make a card transaction without verifying in advance that the card has sufficient funds, so that you can still buy stuff on your card even if the merchant's phone line or internet is broken. In fact, the last-case fall-back is to go back to the swipe machines and carbon paper.


What's Concorde's engine fan blade tip speed at full thrust?

Apart from the fact that the Rolls-Royce/Snecma Olympus 593 engines were pure turbojets so they did not have any fan, it's pretty easy to calculate (better approximate) the tip speed of the first Low-Pressure Compressor's wheel.

The Olympus 593 had a diameter of about 1.2 meters [Wikipedia]. Let's say the first compressor wheel had a diameter of about 1 meter.
As we're talking about the LP Compressor, we're interested in N1 speed. At 100% N1 speed, we are at 6500 rpms [FAA Type Certificate No. E20EU] (for N2, at 100%, 8530 rpms).
Now it's just math to calculate, or, just use an online converter.

The result, as DoRoCro already wrote in his answer, is about 340 m/s.


What can cause a sudden jump in Indicated Air Speed?

Yes, exactly, the change of wind direction is the cause for your sudden increase of IAS.

I have marked your aircraft heading with a magenta arrow and the direction the wind comes from with a brown arrow. So, you are going 140 KIAS at this moment and you have a steady 5 knot tailwind. That means you have a GS of roughly 145 kts (we will ignore air density and that it's not a perfect tailwind in this example).

Now the wind direction changes all of a sudden.

You have now got a nearly direct headwind. That means there are in total 10 kts more worth of air going into your pitot tube and thus indicating 150 KIAS. That's because your aircraft lost the 5 knots tailwind and at the same time got a 5 knot headwind. Because of the fast wind direction change, the aircraft kept its "momentum" and the airspeed increases by double the wind speed.


Was a 7300-mile non-stop flight possible in 1979?

Even for zero payload, no B707 model is able to fly more than 6000nmi (11111km). B727 even has less range.

However, Iranair planned to run Tehran-LAX flight, which length is 12222km, but never materialized because of 1979 revolution. The flight could have been operated by the 747SP (introduced in 1976), similar to their Tehran-JFK route.


How can I isolate altitude as a specific range variable on a Sporty's electronic e6b?

TL;DR; You need to look up the burn rate in your POH.

I think you are misunderstanding the examples...

Your fuel burn rate is determined by your power setting and altitude from your charts in your POH. You need to look that up, so to calculate the range, here is what you do:

First, use your POH to look up your fuel burn for a specific power setting/manifold pressure/altitude, here is an example from a Cessna 172 POH:

You can then you can use that fuel burn rate in your calculations. A range calculation is simply:

$$
Range = {Fuel \above 1pt BurnRate} GS
$$

So using the table above, if we are cruising at 6000 feet @ 2200 RPM on a standard day we are burning 7.7 GPH. The 172 has a capacity of 53 gallons. If we are indicating 100 knots ground speed on a GPS (1knot = 1 nautical mile per hour), we can calculate our rate as:

$$
Range = {53 \above 1pt 7.7} 100 = 688
$$

The result would be 688 nautical miles (this is burning every drop of usable fuel, not taking into account VFR or IFR reserves).


Why does the thrust limit page display the thrust in percentage (« % ») and not in pound-force?

Does it mean the same percentage of takeoff thrust might provide different thrusts according to the operator?

Not just per operator, it is different per engine installation in one fleet. That's why calculations are done according to each airframe's AFM. And as the engine ages, its thrust decreases* (and fuel consumption increases), and this is reflected in the calculations. (The fuel flow (and drag) offsets are based on data from previous flights, and are presented to the pilots as corrections/biases to input.)

    The selection will finally show as a percentage.

The final selection will be percent N1, EPR, or for the latest planes (A350 and 787 with R-R engines) as an actual available thrust percentage. So it depends on the plane/engine/technology.

As to why, because lbf or kN mean nothing at first glance.

The calculations are very complex to do by hand.
Density altitude would make a correct number feel incorrect. In other words, 95% N1 (for example) is a different thrust force at SL at 15°C from at 5,000' MSL at 35°C.

The number simply shows without guesswork or confusion** how much of the available thrust will be used. And it makes the AFM (or EFB) easier to present/use.

* As an example, a heavily used fan will not be in a good condition, so two similar fans (but different ages) running at the same rotation (N1 percentage) won't deliver the same force. (The same for the conditions of the rest of the stages and combustor.)

** Plus, the engine controllers have no way of measuring force, this is another reason why the selected level during flight prep must match the engine instrumentations, otherwise the crew can't verify the takeoff thrust that's been preset, has been achieved.


According to aviation-history.com the design never left the drawing board.

In 1935, the US Navy ordered the XF4F-1 as a backup to the US Navy’s first monoplane fighter, the F2A-1 Brewster Buffalo. However, data from the Buffalo demonstrated that the biplane fighters could no longer match the performance of the monoplane. It was now apparent that biplane fighter's days were numbered as the XF4F-1 performed no better than the re-engined F3F.
The design never went further than the drawing board and the Navy’s thinking had finally reached the conclusion that the navy fighters were lagging far behind land-based fighters. The biplane design was scrapped in favor of a new prototype, designated the XF4F-2 (G-18).


Why are there fewer stages in the turbine than in the compressor of a turbine engine?

Very simply, a turbine has fewer stages than the compressor, because the flow in the turbine is going in the direction of reducing pressure - the air wants to go that way naturally. But a compressor has to make the air flow in the direction of increasing pressure. If this is done too aggressively (attempting too much pressure rise per stage), the air flow on the blade seperates, and stalls. In severe situations, the flow can completely reverse direction and exit the intake.


Is it possible to build a jet engine that utilises all excess heat?

No, any thermal machine always transfers energy from the heater to the cooler (Carnot cycle). The maximal yield depends on the temperature difference and cannot achieve exactly 100%. It is equal

$$
1-\frac{T_\text{C}}{T_\text{H}}
$$

where Tc is the temperature of the surrounding air and Th is the temperature of the burning fuel. Jet engine as normally understood in aviation is a thermal machine.


How many plane crashes are prevented by pilots?

Any manually-flown landing would meet your requirements. If the pilot does nothing on final approach, the plane will almost certainly come to a fiery end.

Landings that were very, very close to a crash aren't reported all that often - if you made some monumental screwup and managed to salvage it, would you write it up for the FAA? Not many people report almost-car-accidents or red light violations either.


How does a labyrinth seal work when the engine isn't rotating?

An example of oil labyrinth seal use

I'm taking the bearing sumps example. There are several bearings to maintain the engine rotors and shafts centered within the core and the stators. Some may use labyrinth seals.

Source.

Pressurized cavity during operation

In a bearing sump with classic dry design, oil is provided directly to the bearing, and labyrinths seals maintain oil within a first cavity (the sump). There is another cavity around the first where compressed air is injected. Air is tapped for internal use from a compressor stage (bleed air).

Source.

This way if oil escapes the first labyrinth of the oil seal, it is contained by the pressure of air coming from the outer cavity on the other side of the seal.

Actually air, which is provided at a higher pressure than oil, will enter the inner oil cavity and mix with oil to form a mist. This is why scavenged oil must then be filtered to separate air when returning to the oil tank (oil must also be cooled has the bearing generates a significant amount of heat).

Oil is directed to the bearing using jet nozzles, the sump is not completely filled. Someone more knowledgeable may explain why, perhaps an oil boundary layer would appear and create unnecessary friction:

Source: Gas Turbines, A Handbook of Air, Land and Sea Applications

In today's engines, oil is circulated using pumps. There are two pumps: One to supply with oil and one to scavenge oil. To ensure oil doesn't accumulate into the sump, the scavenge pump has a higher capacity. Both pumps are driven by the rotation of the engine.

Non operating engine

The pumps are mechanical and driven by one of the engine shafts.

When the engine is not operating, the pumps stop, oil is not supplied any more and it leaves the sump by the scavenge pipe. Bleed air isn't necessary any longer.

When the engine is started, the pumps also start. Oil is therefore injected again into the sump.

The bearing can sustain lack of lubrication for a short time, and there can be an emergency system if oil supply from the tank is interrupted.

Residual leakage

As there will be some limited leakage anyway, oil is extracted by the cavity drain and disposed overboard (or returned to the oil tank).


Why do propeller blades not have winglets?

Winglets on wings help because they increase the volume of air on which the wing can act. Extending the wing span would be much more efficient, but when span is restricted or the maximum wing bending moment is limited, winglets bring a small improvement in efficiency at high lift coefficients.
On propellers, however, the winglets would run through air which is already affected by the tips of the propeller. No additional air will be involved, so no efficiency increase will be possible. Please note that propulsive efficiency is increased by accelerating more air by a smaller amount. The formula for the propulsive efficiency $\eta_p$ of an air breathing engine is
$$\eta_p = \frac{v_{\infty}}{v_{\infty} + \frac{\Delta v}{2}}$$
where $v_{\infty}$ is the speed of the inflowing air and $\Delta v$ the speed increase of the air affected by the propeller disc. A smaller $\Delta v$ acting on a higher mass flow makes the engine more efficient. This effect is most pronounced when $v_{\infty}$ is low.
The prop tip winglets would operate in a region of high dynamic pressure and generate more friction drag without contributing to the prop's efficiency.
Things become different when the propeller blades have a very low aspect ratio and there is a hard restriction on propeller diameter: This is true for ships, where draught puts a hard limit on propeller size. Here a sort of winglet does indeed help: The Kappel propeller has its tip bent forward and increases efficiency by 3 - 6 percent. Given that marine propellers even for large ships have efficiencies between 50% and 60%, this is a noteworthy increase in efficiency.
By the way: Whoever tells you that winglets reduce induced drag quite a bit has something to sell to you, but I digress.


Why most of the supersonic or fighter aircraft use all-moving control surfaces?

The biggest two reasons to have a stabilator (the most common all-moving control surface) are stability at supersonic speeds and increased maneuverability.

As an airfoil approaches its critical Mach number, the diverted flow moving past the wing's leading edge, because it has to move faster than the wing itself to follow the contour, starts to exceed Mach 1 and then decelerates below it, causing a transsonic shockwave to form behind the wing's leading edge. This shockwave causes boundary separation of the airflow at the trailing edge of the wing, where traditional elevator surfaces are placed. This reduces the wing's lift and also the effectiveness of elevator surfaces, a phenomenon known as "Mach tuck". By instead moving the entire control surface, this problem is avoided as the entire airfoil, regardless of the quality of the flow of air over any point of it, is used to direct airflow and thus rate the aircraft's nose.

Second, and more intuitively, the larger the elevator surface, the more air it redirects and thus the more force it places on the tail section, in turn allowing the pilot to pitch the aircraft at higher rates. The ideal endpoint of this line of thought is that the entire stabilizer also becomes the elevator surface; a "stabilator".

Both of these considerations are critical to the design of fighter jets, which as of the fourth generation were almost all capable of Mach 1 (and a few could exceed Mach 2), and which also have to be highly maneuverable even as the moment of inertia of the airframe in the pitch plane increases (an unavoidable side effect of wrapping an airframe around two high-performance jet engines traversing the length of the fuselage).


What's exactly meant by the "slippery when wet" report on ATIS?

why the runway condition is expressed as "slippery when wet" rather than just as "slippery."

Because the runway is normally not slippery, and thus it cannot be described simply as "slippery", but it must be specified when this occurs, particularly when it is wet it is slippery.

Saying only "slippery" would mean that the runway is always slippery, and is not the case.

Saying only "wet" does not convey the information that it is also slippery in that condition. (and you want to specify this because not all runways are slippery when wet)

It is not said "slippery when icy" because "when icy" everything is slippery, so that does not need specification, "icy" is sufficient.

"slippery when snowy" I never heard of it, generally because either the runway gets snowploughed fast enough, or because when there is too much snow the runway gets closed.


Autobrake is a smart system which basically implies that the pressure is applied to the brakes when a set of circumstances are reached, such as when the plane detects that it is on the ground and the thrust is in idle.

There are in principle only advantages with an autobrake system, since it reduces pilot workload during the moments after landings and reduces necessary runway to stop. While autobrake has what I know not been the reason for any accidents, the faulty computer logic of the computers in the autobrake and spoiler system contributed to a Lufthansa accident in 1993.

As I gather, the Fokker 100 autobrake will be activated when the thrust levers are commanded to idle reverse and the system is on. It has 5 settings: RTO (Rejected Takeoff), OFF and LO/MID/HI, the latter 3 representing the amount of automatic brake pressure.

Autobrake is closely related to the spoilers, which are simply a button on the Fokker 70/100. The direct effect of spoilers on the landing gear is that they are pushed harder down onto the runway (since the lift from the wings is disrupted), making the braking more effective early on during landing.

Source (not very good but the best i could find)


Are there any aircraft where the wings are swept forward of the cockpit?

The closest thing from the real world that comes close to the ones you found on deviantart are "Canard Aircraft"

If you read about this concept you will find that it is complicated to implement it succesful.
Then most of the art employ a forward swept wing, this has some complications as well. I would suggest you read some more about the NASA X-29

As far as I know a combination of the two has never been demonstrated in real life and only exist in fiction, therefore there is no general name for as far as my knowledge goes.


What are dimensions of the B-17 propellers?

According to the maintenance manuals from here about halfway down the page (part 1 page 3) the B-17 was equipped with:

  PROPELLER.

  Type: Three-bladed, hydromatic, WEE50-473 or 505,
  full feathering.
  Mfgr.: Hamilton Standard.
  Hub: 23E50-473.
  Blade: 6477A-6.
  Diam.: 11 ft. 7 in.

Part two of the manual has all the installation and setup instructions instructions if you are looking for those as well.

Hamilton Standard seems to have been acquired by (or turned into) UTC Aerospace which appears to still make propellers. You may want to reach out to them as they may have more info on hand. There are quite a few B-17's lurking around and there may even be one near you that you can go take a look at and possibly even measure.


Why are highly cambered airfoils rarely used in propellers or wings?

First propeller use: A highly cambered airfoil would cause high pitching moments and twist the propeller blade. Of course you can pre-twist the blade so it will assume the correct shape in the desired operating point, but a propeller needs to work over a wide range of operating points, from take-off roll to high speed flight at altitude. In off-design points (i.e., most of the time) the propeller would have poor performance when compared with one which tolerates more diverse conditions.

Note that indeed thin, highly cambered airfoils are used on compressors and turbines in jet engines. Those are more stubby and enjoy much narrower variations in flow conditions, so the highly cambered, thin airfoil is indeed the best choice here.

Use on wings: Some aircraft do indeed use highly cambered airfoils. Those with low maximum speed like human powered or electric propulsion aircraft prefer those airfoils because they create the needed lift at the lowest possible speed, so the aircraft can fly with the limited installed power. As soon as the aircraft needs to cover a wider speed range, however, a lower camber is needed to keep drag low at high speed. This is similar to the use on propellers: A wider operating range requires to move away from the narrow optimum offered by those highly cambered airfoils.

Note that aircraft with a high wing loading use extensive and extensible high lift devices which turn their wings into thin, highly cambered structures for landing. Again, as soon as a lot of lift at low speed is needed, thin, highly cambered airfoils are the best choice. Adding slots between segments will make those work even better than a solid airfoil and allow to use more camber.


What is the difference between Line-Replaceable Unit (LRU) and Integrated Modular Avionics (IMA)?

A Line Replaceable Unit is a piece of hardware that can be exchanged for a replacement part in a relatively short time by only opening and closing fasteners and connectors. You will find the term LRU in avionics but also in ATC hardware. Examples are FMC, transponder, etc.
When you have a complex avionics system you tend to end up with a great variety of LRUs. All these LRU have a very specific function. To be able to quickly replace malfunctioning parts, maintenance needs to keep a large stock of spares for all these LRU's.
The Integrated Modular Avionics concept attempts to reduce the variety of LRU's by designing the avionics with common components. E.g. one type of power supply, one type of memory unit, one type of processing board and only a few variations of input/output modules. Instead of working with very function-specific LRUs, the IMU works with more generic Line Replaceable Modules (LRMs). This reduces the number of replacement parts that need to be kept on stock. The LRMs of IMA have more generic functions than in a traditional avionics system.


What is the exhaust port on the tail of jetliners for?

That's the exhaust port for the APU (Auxillary Power Unit).

The APU is usually used to power on-board electronics when at the gate, or used to start the main engines. They may or may not be running while in-flight.


What wind change gradient is necessary to be classified as wind shear?

On one hand this has to do with how wind shear is actually reported which makes it tough to put an official value on it some times. Wind shear is often reported by pilots when they experience it on landing, takeoff or in the air. This may come in as a PIREP and be disseminated out to other pilots. When you are actually in the left seat you will see the manifestation of wind shear as a sudden loss of airspeed or severe weathervaning of the aircraft. There are many conditions that may cause a pilot to report wind shear. Since different planes at different times may experience different conditions its somewhat subjective.

The Wikipedia definition puts it at:

  Airplane pilots generally regard significant wind shear to be a horizontal change in airspeed of 30 knots (15 m/s) for light aircraft, and near 45 knots (22 m/s) for airliners at flight altitude. Vertical speed changes greater than 4.9 knots (2.5 m/s) also qualify as significant wind shear for aircraft.

The FAA has a nice briefing on it here and their definition (as official as its going to get) is:

Frontal Wind Shear

  As with so many things associated with weather, there is no absolute
  rule, but a couple of clues tell you that wind shear may occur:

  The temperature difference across the front at the surface is 10 °F
  (5 °C) or more.
  The front is moving at a speed of at least 30 knots.

Thunderstorm Wind Shear

  These winds can change direction by as much as 180 degrees and reach
  velocities of 100 knots as far as 10 miles ahead of the storm. The
  gust wind speed may increase by as much as 50 percent between the
  surface and 1,500 feet, with most of the increase occurring in the
  first 150 feet.

Temperature Inversion Wind Shear

  One particularly bothersome aspect of temperature inversion shears is
  that as the inversion dissipates, the shear plane and gusty winds move
  closer to the ground. In some areas of the Southwest, a 90-degree
  change in direction and 20- to 30-knot increases in surface winds in a
  few minutes are not uncommon

Wind Shear From Surface Obstructions

  Some airfields are close to mountain ranges, and mountain passes are
  close to the final approach paths. Strong surface winds blowing
  through these passes can cause serious localized wind shear during the
  approach. The real problem with such shear is that it is almost
  totally unpredictable in terms of magnitude or severity

From personal experience low level wind shear can really do a number on small planes. Bigger planes with more mass will still be affected but less so from what I hear. I have seen speed drops of 15kts momentarily and heading shifts upwards of 30 degrees on final approach in a Piper Warrior in even light shear conditions.

Here is an overly dramatic (and personal favorite) rendering of a micro burst causing wind shear

(source)

Some airports (110 in the US so far) have been lucky enough to have Low Level Wind Shear Detection Systems installed which are pretty neat units, they will detect that as:

  LLWAS wind shear alerts are defined as wind speed gain or loss of between 20 and 30 knots aligned with the active runway direction. "Low level" refers to altitudes of 2,000 ft (610 m) or less above ground level (AGL)

Here is a pretty neat overview from NASA of the various methods to detect it in the air.


What is the MEL (minimum equipment list)?

As mentioned here:

  A minimum equipment list is a list of equipment that must be installed
  and operable for the aircraft to be considered airworthy. It is
  aircraft-specific and spells out which pieces of equipment may be
  inoperable while maintaining airworthiness. If something is found to
  be inoperative, the pilot goes to the MEL, finds the entry for that
  item, and determines if the airplane must be grounded until that piece
  of equipment is fixed.

A Master minimum equipment list is:

  An MEL for a specific aircraft originates from a master minimum
  equipment list (MMEL). The MMEL is a list of all equipment on an
  aircraft type; it details which equipment is allowed to be inoperative
  without grounding the aircraft. (Think of a MMEL as a general, broader
  MEL.)

FAA publishes MMELs by manufactures.


What are these aircraft? Seen in silhouette over Palm Springs

Looks like two Douglas DC-3, the one on the right being the military version known as the C-47 "Skytrain".

Source: Adrian Pingstone


The APU is usually located at the rear of the aircraft, in the tail, so the intake is generally somewhere on the side of this location. Aircraft place the inlet in different places though, and some even put the APU somewhere different. For some examples:

737 intake, the small NACA inlet at the bottom

E145 (the place they don't want you to put de-icing fluid)

B777 (the scoop that opens upwards)

A330 (a scoop on the underside of the tail)

B727 (inside of the wheel well)

Here is an interesting thread including other examples.


What is this aircraft on the grass in Budapest International Airport?

It has the distinct shape of the 767, and it is indeed a 767 (registration HA-LHB, ex Malev) as can be seen in these photos:

https://www.airliners.net/photo/Malev-Hungarian-Airlines/Boeing-767-27G-ER/4847571
https://www.airliners.net/photo/Untitled-Malev-Hungarian-Airlines/Boeing-767-27G-ER/4850697
https://www.airliners.net/photo/Untitled-Malev-Hungarian-Airlines/Boeing-767-27G-ER/4808155

By the state of the airframe (and the fact that it is illuminated) it is indeed looks like it is being used as a firefighting/rescue training frame.


Could you use radial blowers to propel a model aircraft?

Interesting question, and I can only answer in general terms because much depends on speculation.

Short answer:

use one central exhaust
one big blower is better than two small ones
one short flow channel is better than two long ones
suction on top might be beneficial for high lift

Radial-flow compressors are very light and achieve high pressure gains per stage. However, the simple plastic thing in your illustration will not have good efficiency. Generally, cambered blades are better than straight blades, and the thinner they are the better. Thick blades block more of the flow path. The drawback is their high diameter, and by placing the blower on its side, you get around this obstacle in an elegant way.

The idea of using two exhausts complicates things; if you use a single one, you can avoid problems due to unsymmetrical thrust. Given that the compressor runs in one of two directions, asymmetries will be very hard to avoid. By placing vanes into the exhaust you can actually give the model plane some degree of sideways thrust vectoring. Also, two flow channels will have more surface area per cross section than a single channel. Your losses will be higher if you use two like in the illustration because they are longer than necessary.

The same goes for the blower: A single, larger one will always be more efficient. The gap size in a small blower is probably relatively bigger than that of a larger blower, and gaps are real efficiency killers.

Another efficiency killer is flow separation in the ducts. Make sure that cross section changes are gradual and avoid bending the flow as much as possible. It will probably help if you install cambered guide vanes at the entry of the exhaust to convince the rotational flow to change direction and leave the round compressor chamber.

Suction on top is also interesting. There have been many ideas about boundary layer suction to increase maximum lift, and your turbine inlet will certainly help to remove some of the boundary layer where it will separate first. Normally, turbine intakes are placed where the normal flow field already shows some pressure increase due to ram effects, but at the speed of a model airplane this will not be a factor. I expect the best intake in your case is a hole on top of the aircraft with nicely rounded edges. Those rounded edges should already produce some lift, and the whole configuration will probably achieve a higher stall angle of attack when the engine runs at full power than at idle power.

I can only speculate how much power will be converted to thrust, but I bet placing an ordinary propeller at the usual place will be more efficient. But the configuration you propose has its own merits.


Can I do a dual VOR check on the ground?

Be careful performing a dual VOR check on the ground, especially if you are located near other aircraft or buildings that may interfere with the signal.  I have performed a VOR check on the ground at a few airports around the Southwest, and I have found that you can get erroneous readings, on the ground, compared to performing the dual check in the air. I would say its more accurate in the air.
As for how to log it. DATE, PLACE, ERROR, and SIGNATURE. Place, meaning the VOR station identifier. 91.171(d)


Why do fighter jets land faster than Jumbo commercial aircraft?

It is not only the mass that affects the landing speed. Wing area plays an important role as well.

A larger wing can lift more weight at the same speed than a smaller wing. If you compare the wing loading of these aircraft the differences are smaller:

A388:

Maximum landing weight: 391000 kg
Wing area: 845 m2
Wing loading: 463 kg/m2

B744:

Maximum landing weight: 295000 kg
Wing area: 525 m2
Wing loading: 468 kg/m2

F-16A:

Estimated landing weight: 13000 kg
Wing area: 28 m2
Wing loading: 464 kg/m2


Why do my ears pop if the cabin is pressurized?

Here is an illustration of how cabin pressure changes during a typical commercial flight:
image source: http://aerosavvy.com/aircraft-pressurization/

Note how when the pressure outside the aircraft is changing, the pressure inside the aircraft is also changing, but not as much.

During the flight shown here, you would experience about the same pressure changes that you would in an unpressurized Piper Cub that only went to 7000 feet.


How should I log time when I fly from one airport to another and back again without landing?

The time from when you started the engine to when you stopped the engine.  It doesn't matter where you went, except for where you specifically need to record the trip details for training requirements purposes, or for your own historical record.  So you'd log the overall trip time, startup to shutdown, adding something like, "CC YYY to XXX back to YYY - no landing at XXX" in the Remarks.


In EASA, what is Panel 12? Is this just the same as Panel 10?

Reading through CM-SWCEH-001, the Background section is identifying the EASA system panels, one of which is identified as the primary panel for certification requirements for the system being developed. My understanding of Panel 10 is that it serves as a secondary panel for some of those requirements.

The document defines Panel 10 as:

  The EASA panel in charge of software and AEH aspects of certification.
  This panel includes at least one software and AEH expert (the
  coordinator) and, depending on the size of the project, may include
  additional software and AEH experts.

I would say that it is not a typo, with Panel 12 being the System Saftey panel.


How energy efficient is an aircraft take off?

You can make a decent approximation with very basic numbers. Take for example the CFM56-7B (which is incidentally also used on the 737NG).

Maximum thrust specific fuel consumption $TSFC$ at takeoff: ~10.9 g/s/kN
Maximum thrust $F$ at takeoff: 121 kN
Jet fuel specific energy $e$:  43 MJ

Combining these figures gives a fuel burn of 1.4 kg/s at takeoff, or 57 MJ of chemical energy released every second ($P=57MW$).

To get an airplane of mass $m$ to a certain speed $v$, it needs $$E=\frac{1}{2}mv^2$$ of kinetic energy. It does so in $$t=\frac{v}{a} = \frac{vm}{F}$$ seconds (remember, $F=ma$). The efficiency $\eta$ is useful work done $E$ divided by input energy ($Pt$),
$$\eta =\frac{mv^2}{2Pt} = \frac{vF}{2P} = \frac{v}{2\cdot TSFC \cdot e}$$

Immediately, we see why TSFC is an important figure. Plugging in some numbers, let's say $V_R =145\mathrm{kts} \approx 75\mathrm{m/s}$, we get a total efficiency of $\eta \approx 8\%$ until rotation.

Note that this calculation assumes constant TSFC while in reality it is very much a function of $v$ (indeed, with this calculation you could have $\eta>1$ if $v\to\infty$ which is clearly impossible).


What is the coordinate system used in an Aircraft?

Stations (STA), generally Fuselage Stations (FS), designate location along the length of the aircraft, increasing from nose to tail. Generally station 0 is somewhere in front of the airplane. One reason for this is that if the airplane grows longer, there still won't be any negative stations, and sections of the plane keep their station numbers. FS 100 can also be placed at an important location (looks like the firewall below).

Water lines (WL) designate location in the height of the aircraft, from ground up. You can probably guess by now that these are holdovers from the marine industry. Like the stations, water line 0 is generally a bit below the aircraft, possibly to have WL 100 at the center of the fuselage, or WL 0 could be at the bottom of the fuselage.

Butt lines (BL) designate location left/right on the aircraft, generally centered in the middle.

While the main system is based on the whole airplane, different parts (like the wings) have their own system of STA, WL, and BL.

The stations are generally in whatever unit is being used for the aircraft. In the US, this is inches.

See this link for an example and further explanation.

For a picture similar to the one below but with more detail, see here.


Does the term track guidance apply only to conventional procedures?

ICAO Doc 8168 "Procedures for Air Navigation Services - Aircraft Operations - Volume I - Flight Procedures" states under 2.1.3 Types of SID:

  Track guidance may be provided by a suitably located facility (VOR or NDB) or by RNAV.

To answer your question: RNAV/RNP SIDs are considered procedures with track guidance.

The better your tracking is the smaller the protection area required (especially for turn construction). So flying inbound or outbound a navaid or having RNAV capabilities greatly increases your precision und therefore allows for procedure construction with relaxed climb gradients in areas with difficult obstacle situation.


Which FAA or EASA regulation does prevent a high wing to cross the passenger compartment?

There is no reference to such a regulation in the design reference books that I have. As I remember, in the F27 the high wing did make the passengers tuck their head in when walking to the rear seats: the wing does cross the fuselage, which makes for a much lighter construction than when placing the wing on top of the fuselage.

Image source

There is also no regulation stating a minimum height between floor and ceiling.
There is statistical data on average passenger length, and design departments of aircraft manufacturers are very much concerned with passenger appeal. So they may be instructing the construction department that the wing must be placed on top of the fuselage, despite the weight penalty, in order to increase market share. Populations are getting taller over time.


What factors determine where an aircraft can dump fuel?

Fuel dumping was regulated by FAA Order 7110.65P - Air Traffic Control, which was canceled in 2006. FAA has the following to say regarding fuel dumping:

  ...If the need arises, aircraft are instructed by Air Traffic Control to dump fuel at high altitudes as far away from the airport or any populated areas as possible.

At present, there are no hard and fast rules (at-least in US, for other countries, see below) regarding fuel dumping and it is left to the air-traffic controllers to guide the aircraft.

The main criteria in determining an are for fuel dumping are:

-Altitude In general, fuel jettisoned above 5000 ft will vaporize before reaching the ground. Due to this, some manufacturers recommend fuel dumping above 5000 ft. In general, the ATC will guide the aircraft to an altitude where it can dump fuel so that it vaporises before reaching the ground.

-Atmospheric conditions The evaporative characteristics of the fuel dumped depends on the altitude and the atmospheric temperature. The aircraft fuel tends to vaporise faster in a warm day.

-Aircraft separation The ATC will try to keep a minimum lateral separation (~5 miles) between the aircraft dumping fuel and other aircraft and also some vertical separation (~2000 ft, according to Order 7110.65P).

Except in case of safety emergency, the fuel dumping is carried out at high altitudes.

Note: Some countries do have fuel dumping regulations, like Switzerland, which says,

  The choice of the dumping area is determined by the urgency of the incident, the actual flight path, meteorological conditions and the general air traffic situation. The aircraft is led to a selected area by the air traffic control to dump fuel. At the minimum speed of 250 knots at an altitude of 6,000 ft, but usually with 350 knots at 14,000-16,000 ft fuel is dumped ... There exist no predefined dumping areas ...


How does distributed propulsion work in a pusher configuration?

The wings don't benefit all that much.  Look at a small airplane from head on - how much wing is directly behind the prop?

My airplane for example, the prop is 86" diameter. The fuselage is 46" wide - so 20" of wing on either side is behind the prop.
The wing itself is 35'6", or 426", so less than 1/10" is in direct prop airflow.

The prop pulls the plane forward, airflow over/under the wing then creates the lift.


What type of aircraft is this Airplane in Riga (junkyard)?

An Su-7U. I initially confused it with a Mig-21 and later with an Su-17 due to the similar nose cone, but you can see the exact airframe on the Museum's website:

The wing fences are a giveaway, as is the tail shape and slightly less prominent intake cone.
From the museum website:

At the beginning of 1960's Sukhoi Design Bureau finished to develop its new fighter-bomber Su-7B («Fitter») and another important task arised — to make two-seat training variant of this type. This objective was urgent because Su-7B was hard to control, especially on landing and critical flight stages. Two-seater, designated Su-7U («Moujik»), destined to make training process easier and quicker for pilots.
Nevertheless Sukhoi team managed to release first Su-7U prototype only in October, 1965 due to its high workload connected with evaluation of Su-7B and another projects. Trainer was a bit longer than Su-7B, also was unmounted one of the two cannons in order to reduce weight. The rest of the armament remained mostly the same. Crew seats were located behind each other under the separate canopies. Rear canopy was equipped with large retractable mirror to improve instructor's field of view on take-off or landing. Also instructor had full set of instruments and controls and was able to interfere in flight whenever he decided. Emergency ejection system allowed crew to leave aircraft in dangerous situations separately and safely.
Su-7U production commenced at Komsomolsk-na-Amure Aviation Factory in 1966 and continued till 1971, together with Su-7BKL and Su-7BMK manufacturing. Two-seater' export modification Su-7UMK was bought by Algeria, Afghanistan, Egypt, India, Iraq, Syria, North Korea, Poland, Czechoslovakia and took part in 1970-80's wars and conflicts. Soviet Air Force used Su-7U for very long time — till beginning of 1990's, because of its similar performance with Su-7B's successor Su-17.
Museum's Su-7U serialled 43-red and has production number 2318.


Is possible to stick two '2-blade' propellers to get multi-blade propeller?

Sure, this is not only possible, but even has some advantages over single-plane propellers. The catch is you ideally want the two to spin in opposite directions to cancel out torque and vibration.
You're building a contra-rotating propeller:

Pictured is a Sun Flightcraft contra-rotating gearbox kit for Rotax 503 and Rotax 582 engines.
Although more efficient (on the order of 10%) than single-plane propellers, they are also much more complicated to design. The gearbox will be heavier and harder to maintain. And they are also often much louder, although the Rotax kit pictured above is claimed to be quieter.
They're not just for small engines. Here's a Tu-95 strategic bomber:

On helicopters, the same idea is called coaxial rotors:

"Co-rotating" propellers are also possible, but far less common, as the key advantages (efficiency and cancellation of torque and vibration) are reduced or lost. I could only find some academic papers on it. Here is another.


What is the certification process for a new propeller blade design?

The airworthiness regulations specify functional requirements. They do not specify materials, form, etc. Thefore, the regulations in themselves do not prohibit innovation using new materials or construction techniques, so long as the final product meets the same functional safety requirements as any other design.
It is the manufacturer's responsibility to submit the required proof that a design meets the requirements. I'm not a "propeller guy" but for engines, there is usually a round of pre-certification discussion with the certifying authorities (e.g. the FAA or the equivalent in other countries) to agree exactly how the demonstration of will be carried out - for example whether by modelling and computer simulation, or by testing the finished product. In the case of computer simulation, this will include the method by which the software was verified (i.e. "how do you know that the software actually does what you think it does") and how the model was validated (i.e "how do you know if the model results are consistent with real life.")
The US certification requirements for propellers are Part 35 of the airworthiness regulations, and publicly available here.
Of course the entire process is carried out by humans, who are fallible. The regulations are often updated as a consequence of their failure - and not just for newsworthy major failures like the B787 battery fires of the B737-MAX problems.


Why isn't the course fixed along an airway?

Isn't it supposed that an airway has always the same magnetic course between navaids?

No. The course depends on where you plot it from.

That's a random RNAV airway I picked, it has two headings, 114° and 298°, and the difference is not 180°, it's 184°, so over the course of 112 nm there is a 4° shift.

That's due to the curvature of the Earth.

Consider the following image carefully, notice the North-South needles, how they look on a 2D projection and on the actual globe.

Source: Wikipedia

That's the shortest path connecting those two points in South Africa and Australia.

If I'm in South Africa, looking at Australia, I'll look toward 141° (not 90°), as I get closer, this converges on 42°. If I look back from Australia, I'll face 222°. The difference between 222° and 141° isn't 180°.

If your airway exceeds 150 nm, this becomes noticeable. It becomes even more noticeable if you are flying between distant RNAV waypoints (e.g. NAT route), your heading (track to be more precise) will keep changing.

If you chase a true heading, and keep it constant over a long distance, this happens:

Source: Wikipedia

That's a very long turn, not straight-and-level flying.

Flying a great circle route, or staying on an airway between two navaids, requires flying a course, not a heading/track. The course's heading is only valid from where you plot it / start it. Along that course (i.e. route), the track keeps changing as the first image illustrates, and you're not turning.

An advanced autopilot follows the route computationally; a pilot hand flying would intercept the course, keep the selected course unchanged, and fly the deviation. If no factors (e.g. wind) push the plane off course, no turn inputs will be needed and the actual course will shift as the plane flies straight-and-level. The Course Deviation Indicator won't show any deviation because there isn't any.

Where It Starts

To further clarify why the course depends on where it starts, it's the fact that a VOR station—for example—transmits the radials in straight lines, those straight lines translate to a curved line on a 2D projection. They don't appear curved on a chart because the distances aren't big, even for the most powerful high altitude VOR station.

Hypothetically, if VHF had a huge range and wasn't limited by line-of-sight, VOR navigation would have become a bit confusing the farther out you are from a station.

Speaking of VOR

Just for the sake of completion, you'll notice I focused on RNAV waypoints. There's another factor affecting VOR stations. Two nearby VOR stations may have different alignments to the magnetic north. It depends on when they were built. One could be 20 years older than the other.

Once they're built and aligned, they are in most cases never re-aligned when the magnetic declination changes. It has to do with the cost and the redrawing of airways.

That can amplify the shift further.

So, think of a radial's heading as a highway marker.


Where does an FMS wind information comes from to calculate V approach?

It uses the wind entered in the PERF APPR page to correct the computed VAPP:

Takeoff, performance and go around speeds
[...]
The FMGC uses the performance model and either the predicted landing weight or the
current gross weight at transition to the approach phase to compute approach speeds
(VLS, VAPP, F, S, Green Dot). On the PERF APPR page, the selected LDG CONF determines
the applicable VLS and VAPP, the latter being updated by the WIND correction that the pilot
enters on the same page.

(A320 FCOM - Autoflight - Flight Management - Performance, emphasis mine)


What is this gigantic dish at Ben Gurion airport?

It is just a design feature, and serves no technical purpose, beyond filtering some light and providing a waterfall feature.

  Safdie designed the roof of the rotunda as an inverted dome, an asymmetric dish floating above the piazza that lets sunlight in and filters the daylight with a special white fabric ceiling.
  source: https://www.bdcnetwork.com/ready-takeoff

and

  Rain falling upon the suspended dome drains towards the center and enters the rotunda through an oculus skylight as a waterfall. In the dry season, a continuous flow of water washes the roof, contributing to the rotunda’s cooling and forming a fountain through the oculus.
  source: https://www.safdiearchitects.com/projects/ben-gurion-intl-airport-airside-terminal

Image, because it looks nice (Same source as second quote above)


What would cause an RPM drop and engine cutoff after starting a Cessna 152?

Gradual power loss would not be caused by "air in the fuel lines".

The most likely cause is blocked vents. There are pipes that allow air into the tanks so the fuel will flow out. If they are blocked for any reason, fuel will stop flowing, often in a gradual manner.

Another possibility is that there is corrosion or sediment which is blocking the fuel line. Are you checking drain valves on every preflight and after refueling?


Ramstein is a major US logistics airbase in Germany. Originally Ramstein used to have only one runway. The runway was built with fighter aircraft in mind and could also host C-130 Hercules aircraft. Bigger freight aircraft and passenger aircraft could not use Ramstein and were handled at Rhein-Main base, which was at Frankfurt's international airport.

When Frankfurt needed to expand their civil operations, Rhein-Main base was closed and all the US military tranport operations were transfered to Ramstein. In order to accomodate the big transport aircraft at Ramstein, the airport needed an upgrade. To keep the base open during construction works it was elected to convert the old India taxiway into a runway (08-26) which was made longer, wider and thicker that the original 09-27 runway. Also new aprons were added to the North and South of the runways. When the work was completed in 2005, the old runway was closed for reconstruction. It was then resurfaced and extended so that since 2008 there are two operational runways at the airport, so that in case of maintenance or an incident the operations can continue.

There is no relation to launching fighter aircraft in rapid succession.


Who activates the fasten seat belt warning on commercial flights?

It's P1's decision, and P2's hand that moves the switch.
But, there's a really nice position of the switch, "Auto", which switches them on/off automatically based on some rules (which are usually passing through 10,000ft). Using the "Auto" position means that you can't forget them!


Why does the Sukhoi-30 MKI have both canards and conventional horizontal stabilizers?

Yes, increased maneuverability and redundancy are the main benefits of this layout. Another is a wider possible range of the center of gravity.

In the video linked in Federico's comment you can see that the canards reach high negative deflection angles in high-alfa attitudes: This means they will still operate in attached flow when wing and tail are already fully stalled. A canard-less airplane would only have thrust vectoring for control in this situation. Also noticeable in the video is the negative static stability which becomes evident in the lively elevator movements during the landing approach towards the end of the video. When you need agile pitch controls for artificial stability, it helps to have a second pair of them in highly dynamic maneuvers. The small size of the canards might be misleading: Since they will affect the flow over the inner wing, they are quite effective and powerful control surfaces.

A multirole, long-range aircraft will have to deal with a wide variety of ordnance and fuel loads, so the addition of canards will allow to trim a wider range of c.g. positions. Without them, some load configurations, and consequently some missions, might not be possible.


Would this modified tire work to prespin an aircraft tire?

The idea is good in concept but it would be pretty difficult to match the rpms to the actuual ground speed, in fact if the wheel was spinning faster it would actually wear the tyre more!

Another factor is that aircraft wheels often do not hit the runway straight on. In a crosswind situation they could be off a few degrees so the tyre would still scrub.

Also the fact that adding weight is anathema to airplane designers, not only the motors but electronic controllers and associated wiring. This weight will have to be carried for the duration of the flight.

Finally the hardest working part is not the tyre but the wheel bearings.. on a longer widebody flight they go from cold-soaked to very hot in a few seconds. Tyres actually fare pretty well, I've seen new tyres fitted and come back after a few sectors which still looked pretty new.

As mentioned by John K in the comments above, its cheaper to recap they tyre.


Is it dangerous for a supersonic aircraft to fly at exactly Mach 1?

Make sure to read this answer to understand what is special about Mach 1.
Pilots regularly report that, approaching Mach 1, the airplane is shaken by oscillating shocks (they don't use that term, though, they speak of buffeting) and once the Mach meter needle crosses the 1, the airplane becomes calm and flight smooth again. Since the flow speed around the airplane is normally a bit higher than flight speed due to the displacement effect and the need to produce lift, supersonic pockets start to occur as early as at Mach 0.6 (depending on the particular design) and expand the closer flight speed comes to Mach 1.
Swept wings delay those Mach effects and the peak of the drag coefficient of supersonic-capable designs is also delayed to somewhere between Mach 1 and 1.2. While the drag coefficient normally drops a bit past this peak, drag itself normally rises with speed. Flight at Mach 1 is particularly inefficient but, apart from that, drag is not an issue.
What is more important is the shift in the center of pressure when changing from sub- to supersonic flight. It will move aft and requires the pilot to re-trim the airplane. Supersonic-capable designs normally use full-flying tails for that and delta airplanes raise their trailing edge flaps. Concorde added pumping fuel aft and the XB-70 reduced the rear part of the wing by folding its wing tips down. When flying at Mach 1, the airplane is smack in the middle of the largest pitch moment change over speed range, so any change in speed means also a strong change in pitch moment. When no trim change accompanies that change in speed, the airplane will be unstable in pitch: Flying faster will move the center of pressure aft and make the airplane dive (Mach tuck), speeding up more, and vice versa. Reducing speed might even lead to structural failure from the sudden pitch-up and increase in load factor if not corrected by control deflections.
That is what makes flight at Mach 1 unadvisable. If the pilot or the FCS keep pitch under control, flight at Mach 1 can continue until the fuel runs out and the airplane hits the ground, causing speed to drop dramatically.


Get lots of airspeed,pitch up within ac flight envelope limits and as you approach stall speed for your configuration, push forward so that 0 G is shown on the g meter, and keep it there.
As you come over the top pull out again within it's so you neo not exceed Vne,Vmo or Mmo or g limit's for your planes . A parabola for a few minutes or second depending on the plane.


During multiengine training, are pilots taught how to use the throttles for control?

No.  In a piston multi course the focus is on flying the airplane and single engine procedures.  Loss of rudder control in something like a Seminole is not a big deal unless the engine quits after that and then you have a problem, and it's not one of controlling yaw with differential thrust.

If your rudder cables broke with both engines running you would naturally use bits of differential power to center the ball as required while flying straight, and little rudder is required to turn so that's not a big deal and you would just leave it and put up with a bit of adverse yaw. This all wouldn't require much training to figure out.

Sioux City was what you would call a freak event, with multiple simultaneous failures of flight controls for all axes, that is not catered to in design in the first place (notwithstanding the mistake, on the DC-10, of running all the hydraulic lines though one choke point; most airplanes separate control runs as much as possible to cater to turbine burst events).  They were trying to control both pitch and roll, with differential thrust to turn by skidding and by using the pitching moment of increasing/decreasing thrust to climb/descend.

No type course trains for that.  There are a million one-of-a-kind events you can dream up, which can theoretically happen, for which airliners are not certified to cope with, and where a crew might have to figure things out on the go.  If you had to train for all of them, the type course would take years to complete.


Are electromechanical actuators used in aircraft other than the Boeing 787?

Electromechanical Actuators are used in many aircraft, and in many applications.
Applications vary from controlling doors,  trims, control surfaces, flaps and air inlets to moving your business class seat to the most comfortable position.

For quite a range of examples see the product website of this manufacturer.

Or this video of an aileron application


Can instruments be fixed via a swift punch?

If the static port gets blocked in an aircraft with no alternate static port, you can break the glass of the VSI (Vertical Speed Indicator) to allow air from inside the cockpit in the static system. By doing this you will sacrifice the VSI in favour of the altimeter and airspeed indicator

Due to venturi effects, air inside the cockpit has usually a slightly lower pressure than the pressure measured by the static port outside your aircraft.

This causes your altimeter to indicate a higher altitude and the airspeed indicator will also indicate a greater speed. The VSI is useless after you break it.

Needless to say this does not apply to pressurized cabins nor to glass cockpits...

This works because the inside of the VSI contains a diaphragm in a pressure chamber. The diaphragm is connected to the static system through an unrestricted tube. The chamber is connected to the static system through a  restricted (calibrated) leak. If the static pressure changes, the pressure in the diaphragm  changes instantly, while the chamber pressure lags slightly behind. This causes the membrane to expand / retract which drives the needle on the instrument.

When the glass is broken, the chamber will be at the same pressure as the cockpit. Through the calibrated leak, the static system will be levelled with the cockpit pressure, but of course with a delay as well. The VSI will now work in opposite direction (if you didn't destroy the needle).

The inner workings of an IVSI

Some VSI apparently have the calibrated leak into the cockpit already. For such VSI's smashing the glass does not work. Here the diaphragm should be destroyed as well.


How does ATC direct aircraft on ground from the parking to the runway?

Yes, it's the same. An airport consists of one or several runways, one or several parking areas (aprons) and a number of taxiways connecting them. All runways and taxiways are uniquely named.

When taxiing around the airport - be it from runway to parking, or vice versa, or between parking areas, hangars etc. - ATC instructs the pilot of the exact route to follow by specifying the taxiway names in order. ATC can also instruct the pilot to stop and wait at a certain position, or to follow or give way to specific other aircraft. Some airports, in addition to named taxiways, have named holding points around the airport which can be used to specify where the aircraft should stop and await further instructions.

Pilots who are not familiar with the airport will have no problem following instructions, since they all have a ground chart (essentially a street map) of the airport layout, with all the taxiway and runway names.

Example of aerodrome chart - Copenhagen Airport, reproduced from AIP Denmark

Some modern airliners even have a moving map which shows the aircraft GPS position directly on a digital airport map in the cockpit. In addition, signs are posted at all taxiway and runway intersections, showing the name of the current and any adjacent taxiways and runways.

Taxiway signs

In extreme cases, ATC can make use of turn-by-turn instructions (progressive taxi), but that is very rarely needed. Follow-me/marshall vehicles are also available, but those are usually not to help the pilot find the way, but rather to provide an extra set of eyes when taxiing very big aircraft, to ensure they stay on the pavement during a narrow turn/tight gap etc.


Will ICAO 24 bit addresses suffer the same fate of IPv4?

I don't think there will be an ADS-B mandate specifically for drones. Instead I expect ADS-B will be mandated for certain airspaces.

The US has taken this approach from the beginning, Australia has a combined airspace & flight rule approach (IFR in class A,B,C & E airspace). The EU so far has based the ADS-B mandate on aircraft weight (>5700 kg MTOM) or speed (>250 KTAS). That is likely to change in the future.

For drones operating outside this ADS-B mandatory airspace, no ADS-B will be necessary. I guess the number of drones inside mandatory airspace will be limited, since there is no efficient way to integrate them into the Air Traffic Control system. However, over time this will likely change.

The big problem I see is not so much the limited address space, but the overloading of the 1090MHz frequency that ADS-B will be working on. On the long term I see a need to rethink frequency allocation for surveillance and navigation (and while we are at it, communication too). The limited number of addresses should be dealt with at the same time. With so many investments in the current system, it is going to be very difficult to transition to a new system.


Why the excessive wait after shutdown before using the manual starter valve on the PW1000G?

The FCOM page reports MSN 7172 which corresponds to an A320neo with PW1127G engines. Why is this important? Because this engine family is prone to bowing, so much that it requires a dedicated cooling procedure on start performed by FADEC:

However, the ENGINE START VALVE MANUAL OPERATION procedure requires you to perform the MAN START of the engine, which disables many safety feature of the FADEC and does not permit the FADEC to close the start valve in case of the detection of an abnormal situation (this is actually the reason why you want a MAN START). So, I suspect it also disables bowed rotor protections, and this is why that procedure requires the engine to be completely cooled down.
If you are wondering how is possible that 9 hours are necessary for the engine to cool down, consider that such engine requires about 2 minutes of forced cooling even after 1 hour since shutdown (source). The most critical point for is around 2 hours since shutdown (source). In some forum you can find pilots reporting ~6 hours the needed time for residual EGT to go to ambient temperature for LEAP engine, which is even less problematic for thermal characteristics compared to PW.
So it's reasonable to think that the engine core with its massive thermal capacity may require many hours to reach ambient temperature, and the need of MAN START probably disable safety features that would avoid bowing, which does not allow you to start the engine if it's still hot.


Why can't flight management systems receive instructions directly from the controller?

Short answer: it's coming soon.

For why can't they, the answer is limited data transfers at the moment, which is being worked on.

See: How can shifting to TCP/IP make current aviation systems more delay-tolerant?

Once implemented, it will be like the current CPDLC, where an instruction awaits the crew to press accept, reject, or cancel. A plane like the Boeing 787 already supports simple instructions to be loaded directly into the Mode Control Panel (MCP): the pilot's interface with the autopilot for the different lateral/vertical modes. The 787 is also ready to accept route changes from ATC via the FMS:

Boeing 787 CDU message for accepting a route uplink from ATC. The crew can then press LOAD FMC to view the changes before activating it.

See MCP interface here: What are the differences between ACARS and CPDLC?

When to expect it?

In ICAO's Global Air Navigation Plan, it is expected to be in 'Block 1':

  FANS3/C with CNS integration (via ATN B2) will be
  available providing communication and surveillance
  integration through a connection between the
  FANS and NAV (FMS) equipment. This avionics
  integration typically supports the automatic loading
  in the FMS of complex ATC clearances transmitted
  by data link.

(Emphasis mine.)

Block 1 is between 2018 and 2023. Of course it requires new equipment on airplanes alongside the new ground equipment.

You give an example of an instruction to intercept the ILS. With the avionics integration discussed above, the ATC will receive a downlink from the airplane for its FMS computed performance (e.g., descent performance based on weight and winds). And based on that the flight will receive an uplink with the assigned optimized arrival route to the runway based on 4D navigation (3D + time). The pilot then needs to arrive at each 'checkpoint' at the correct time for traffic separation. This is an example of a "complex ATC clearance".

Above example is still a decade or more in the future (Block 2). The implementation will be in steps. Of those steps is the extension of the arrival management to the en-route area, to be deployed in late 2023 in Europe.


Why am I seeing extremely high L/D ratio of (e.g. L/D = 90) in my 2D airfoil analysis?

The difference is that one figure looks at 2D flow around an isolated airfoil, where L/D ratios of up to 200 can be reached, while the other figure is for the 3D flow around a whole airplane, warts and all. The additional sources of drag which are absent in 2D flow around airfoils are:

Induced drag. This will double the total drag right at the polar point of best L/D.
Fuselage and tail drag. Of course isolated airfoils only have their own surface where friction drag occurs, but all the non-lifting parts on whole airplanes will bring D up without helping L.
Lift loss at the tips. L/D for airfoils uses the pressure distribution and maybe a drag rake at the windtunnel center section, so no tip effects will tarnish the result, but the outer wings of airplanes will have reduced lift relative to the local surface and drag because of tip effects and to improve stall behavior.
Trim drag: The tail can very well add a downforce to balance the lengthwise lift distribution with the location of the center of gravity. Now extra lift has to be produced by the wing, and both, downforce at the tail and extra lift on the wing, will produce more drag.


Is it practical to integrate turbofan or ramjet engines into an airliner wing?

The first turbofan, the Rolls-Royce Conway, had a bypass ratio of only 0.25 in order have a small enough diameter for placement in wing roots. It was initially planned for the V bombers and planned civilian derivatives of them. So yes, it is practical to place a turbofan engine in the wing, but comes at a cost:

Buried engine placement will shift the optimum to smaller bypass ratios, which reduces fuel efficiency.

Next, now your leading edge is occupied by an intake and cannot use any of the possible leading edge devices to increase lift at low speed for take-off or landing. The same goes for the trailing edge. The consequence is:

Buried engine placement will require a larger wing because the use of high-lift devices is not possible near the engines.

Larger wings weigh more and produce more drag in cruise. The last reason might be the most important: In operation, a podded engine is much easier to service and to repair than a buried one. The lower maintenance cost was the main driver for podded engines in the later members of the first generation of airliners (Boeing 707, DC-8, Convair 880).

Buried engine placement drives maintenance cost up.

There are fewer designs with ramjet engines, many of which never took to the air. Here, placement in the wing plane was mostly chosen to avoid thrust-related pitch moment changes. However, a ramjet is best used at high speed, and then you need to keep wing thickness down in order to reduce wave drag. Therefore, the engine placement cannot really be called buried anymore, but is closer to the buried than the podded variety.

The best example is the Lockheed D-21 drone pictured below (source). Since the aircraft is practically a ramjet with wings, the engine dominates the appearance.

Due to the high thrust needed for supersonic flight, supersonic aircraft keep their engines close to the wing and designs with podded engines like the Convair B-58 or the Myasishchyev M-50 were the exception. Stealth aircraft want to hide the hot exhaust and often use an overwing exhaust location which makes their engine placement also a buried one. You might argue that the engine of the Lockheed RQ-3 pictured below (source) is actually in the fuselage, but being a flying wing it does not have one:

The RQ-3 and similar designs like the Northrop B-2 clearly show that a turbofan engine location inside the wing is very practical indeed.


Why isn't there a "check engine" light in airplanes?

With a few exceptions (modern aircraft engines with FADEC systems) a "Check Engine" light on an aircraft would be essentially useless.

In a modern car we have an Engine Control Unit which manages things like mixture and engine timing. The "Check Engine" lamp illuminates when the ECU has detected a fault that requires some sort of attention, but it's not usually specific as to what the fault is or how urgent the problem is.

In most light GA aircraft (like the Cessna or Cirrus in your question) the engines are straight out of the 1950s/1960s: There are no computers managing the engine for you, and the pilot is acting as the ECU.
The pilot should be checking the engine's health regularly (by looking at the engine gauges) and adjusting power, mixture, and propeller pitch as required.

Since there is no computer supervising the operation of the engine in most light GA aircraft there's no system to determine when the light should be on, so there is no "Check Engine" light.

Note that some light aircraft do incorporate warning lights for system status information. For example, the status cluster on newer Piper Warriors:

Top row: Low bus voltage, Pitot Heat off/inop, starter engaged.
Middle row: Vacuum inop, Alternator inop, Oil Pressure.
Bottom row: Not used on this aircraft.

The information provided by these lights is more specific than simply "Check Engine" - directing the pilot's attention to a specific system or condition. The lights are also not a substitute for regularly scanning the engine instruments and managing the powerplant, they're merely a supplement to catch your attention between scans.


Swing-up canopy not shut in high-speed flight, what would happen?

(Source) T-38 Talon

Yes, it's possible. If it didn't separate, then it needs to be checked after the scary and cold flight is completed.

There will be warnings if the canopy is not closed shut.

(T-38 Talon Pilot's Flight Operating Instructions)


Where can I find a free list of ICAO and IATA airport identifiers?

It depends on whether it should be reliable enough to be used operationally. If yes, I don’t know one and would to the best of my knowledge advise spending some sort of money. If no, maybe openflights.org could help?


Why would a jet engine use cannular combustors if the annular design is superior?

Single combustor cans are simpler to develop. To get the ignition and combustion process right in an annular combustor is quite a challenge. When the first jet engines were developed, Junkers decided for separate cans while BMW wanted to design a theoretically superior annular combustor. In the end, the troubles with the combustor meant that Junkers got their engine fielded much earlier, even though BMW had started their jet engine development before Junkers.

With today's CFD tools the annular design is not quite such a challenge any more.


Is it possible for a person to fly with mechanical wings attached to his torso?

You could reasonably call a hang glider "wings strapped to the torso" for this purpose -- hence the answer is "yes, sort of."  With a well designed glider, one can launch from sloping ground and soar on slope lift or thermals, limited by oxygen requirements and fatigue.  Hang gliders have done cross country flights running to many hours, stayed up literally dawn to dusk on ridge lift, and flown high enough for the pilot to require oxygen (and then some, I believe the altitude record is around 18,000 feet).

None of this, of course, is powered by the pilot, using either arms or legs, but this is clearly "wings strapped to the torso."

Add a small engine and you get a modern ultralight/microlight, or something like Rocketman's jet powered wings.  The latter, especially, is still pretty clearly "wings strapped to the torso."


What prevents companies like Cessna and Piper from connecting multiple alternators to a single engine?

You almost answered the question yourself.

Having more than one alternator would introduce more complexity not only mechanically but also in the electric system (even if they work correctly). Alternators scale really good so that a bigger alternator generates more electric power then two smaller of the same weight.

So the only reason to do that on a smaller air plane is to have a backup if one of them fails.

This brings up two questions:

How often do alternators fail?
what are the consequences of a failed alternator?

For the first question I have a (non representative) experience:
At my airfield 6 SEP plane are are posted. In 25 years I'm flying there we had 1 failed alternator.

For the second question we have to look in the flight instructions and the planes manuals. For smaller planes like those you mentioned they state that you should turn off some electric devices and land on the next reachable airfield. That means there is no immediate risk when an alternator fails.

The conclusion is that we simply don't need more than one alternator in a SEP plane.


What is the effect of non-LASER light sources on pilots?

The short answer is "If you intentionally pointed the Luxor beam at an aircraft (flying low enough for it to constitute a hazard) you would probably be arrested".  The real question is What would they charge you with?, and the FAA regulations aren't where you want to look for that: You need to look in the "United States Code".

18 U.S.C. 39A makes it an offense to aim a laser pointer at an aircraft. It goes on to define "laser pointer" as:

  any device designed or used to amplify electromagnetic radiation by stimulated emission that emits a beam designed to be used by the operator as a pointer or highlighter to indicate, mark, or identify a specific position, place, item, or object.

The Luxor beam certainly isn't that, so you're safe there.

Instead you will probably be charged under a creative application of 18 U.S.C. 32(a)(5), which says

  Whoever willfully … interferes with or disables, with intent to endanger the safety of any person or with a reckless disregard for the safety of human life, anyone engaged in the authorized operation of such aircraft or any air navigation facility aiding in the navigation of any such aircraft … shall be fined under this title or imprisoned not more than twenty years or both.

While this law was originally conceived to deal with in-person threats (kicking down the cockpit door and clobbering the captain with a frying pan) it would not take a very creative US Attorney to make the argument that shining a 40 billion candela light at an aircraft's cockpit would "interfere with or disable" the flight crew, and shows a "reckless disregard for the safety of human life".
Similarly it would not take much creativity to argue that swinging such a beam around in the sky in an area where it may interfere with aircraft operations would also show a "reckless disregard for the safety of human life", unless you took the time to file an appropriate hazard NOTAM.

Note that in my initial statement I said that you would be charged if the aircraft were flying "low enough for it to constitute a hazard" -- as has been pointed out non-coherent light source intensity falls off according to the inverse square law, and with sufficient altitude the Luxor beam is just a bright spot on the ground and doesn't have anywhere near the effects of laser illumination.

The Luxor's beam was in fact part of a study on the effect of lasers and high intensity lights in relation to air traffic safety. That section of this report (and indeed the entire thing) makes for interesting reading.


Can a Private pilot fly a company aircraft for business purposes if he is not being paid?

I'd say you'd be on thin ice with this. The principle is that private pilots cannot be compensated for their flying, with very few exceptions. That doesn't necessarily mean getting paid to fly, it can mean having the expenses of the flight given to you in some way.

Say you take 3 friends on a trip, and your friends pay all the costs. You'd be in violation of FAR 61.113 because you haven't paid your share, in other words you've received compensation. You need to pay 1/4 of the costs of the trip.

In another case you are going on a business trip and decide to fly yourself and your employer pays all the expenses. This is legit because flying is incidental and not the purpose of the trip.

In the case you are stating you have no reason to be flying the airplane other than the flight itself, therefore flying for free means you are receiving compensation and a violation of FAR 61.113.

Note other countries may vary, the UK is extremely similar to the US on this, as are most European countries, I can't speak for anywhere else.


What is the metal bit in the front of this propeller spinner?

It is a fitting for a Hucks Starter.

Photos from Vintage Wings Canada


In case of emergency, is it possible (doable) to land a small propeller-driven aircraft on an aircraft carrier?

A South Vietnamese Air Force Cessna O-1 landed on the USS Midway at the end of the Vietnam War. Fixed-wing VNAF aircraft usually flew to Thailand, and the naval evacuation was carried out by helicopter (with crews sometimes ditching in the water after the flight decks ran out of room), but this O-1 pilot wound up making his first carrier landing, with his family on board and an hour of fuel left.

Wikipedia wrote a paragraph about it and has another couple photos.


Yes, the SR-72 project has indeed been officially announced. Lockheed confirmed it to Aviation Week back in 2013. Apparently it actually did get quite a bit of attention at the time, enough to actually cause Aviation Week's servers to go down for a while after the announcement.

The source quoted in the question is correct that Lockheed's announcement did confirm that the SR-72 would be hypersonic:

  But now Lockheed Martin believes it has the answer. “The Skunk Works has been working with Aerojet Rocketdyne for the past seven years to develop a method to integrate an off-the-shelf turbine with a scramjet to power the aircraft from standstill to Mach 6 plus,” says Brad Leland, portfolio manager for air-breathing hypersonic technologies.

Also, from Lockheed Martin's own website, confirming both the Mach 6 capability and the intention for it having at least the option of flying unmanned:

  Envisioned as an unmanned aircraft, the SR-72 would fly at speeds up to Mach 6, or six times the speed of sound.

According to Lockheed, a technology demonstrator aircraft may be flying by 2018:

  Lockheed has run scaled tests on components. “The next step would be to put it through a series of tests or critical demonstrations,” Leland says. “We are ready for those critical demonstrations, and we could be ready to do such a demonstration aircraft in 2018. That would be the beginning of building and running complete critical demonstrations. As of now, there are no technologies to be invented. We are ready to proceed—the only thing holding us back is the perception that [hypersonics] is always expensive, large and exotic.”

Here's a rendering of the proposed design from the SR-72 Wikipedia page:

Source: Wikipedia, which apparently took it from Lockheed's website.

Lockheed was recently awarded a grant from NASA to study the viability of their proposed combination turbine/ramjet engine solution for the SR-72.

  Task Order No.NNC15TA03T provides for a parametric design study to establish the viability of a Turbine Based Combined Cycle (TBCC) Propulsion system consisting of integrating several combinations of near-term turbine engine solutions and a very low Mach ignition Dual Mode RamJet (DMRJ) in the SR-72 vehicle concept. Task Order NNC15TA03T is issued under Contract NNC10BA08B on a firm fixed price basis. Firm fixed price is $892,292.


How do I log simulator time in my logbook as a CFI?

Buy a second logbook
Here's one that costs $11
As a CFII who had exactly the same problem that you did, I can tell you that this is the easiest and simplest way to keep your simulator dual given and your airplane dual given separate.  You just log all of your simulator time as if it was airplane time, but in a simulator.  So, flying a sim that emulates a multi-engine airplane? Airplane Multi-Engine Land column!  Put the student in the soup?  Actual instrument column! Record the serial number of the AATD in the "Aircraft ID" column and you're all set!
But it would be simpler to have just one logbook...
In that case, see if there's an unused column in your logbook that you can cross out and relabel as "simulator dual given".  Airplane Single-Engine Sea works well for this.
Isn't there some kind of technology that could solve this problem?
Sure is!  Electronic logbooks are the bee's knees.  Try Zululog, I don't use it but it's free so if you hate it all you've lost is some time.  Foreflight has a logbook option too. I don't like it (it seems lightweight to me) but you might.
Can I log flight simulator time?
Technically you can log anything you want, including passenger time, chair flying time, and time spent in the hangar arguing about taking off from a treadmill.  The question is whether or not that time is valuable toward future certificates, ratings, or employment.  Dual given as an instructor in a simulator is, sadly, not at all valuable.  No one really cares and you can't use it toward any certificate or rating that I'm aware of.
Which is why you want to log your simulator instruction in a separate logbook; assuming you're not planning to instruct for the rest of your life like me, when you go in for interviews you'll be able to just bring your aircraft logbook and leave the simulator one at home.


This is the nearest you will get to aerobatics. You can check out their website for more information.

Company History
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approval for G-FORCE ONE, a specially modified Boeing 727-200, to take
passengers on commercial parabolic flights. In August 2004, ZERO-G
flew its first commercial flight operating under the same safety
standards of all major air carriers and established its place into the
extreme tourism industry as the first and only commercial Zero Gravity
flight for the general public.
Additionally, in April 2006, ZERO-G became the first commercial
company to gain permission from the Kennedy Space Center to use the
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flights.
ZERO-G has provided thousands of individuals the opportunity to
experience weightlessness including clients Stephen Hawking, Martha
Stewart and Buzz Aldrin.
ZERO-G not only caters to private clients but various organizations as
well. For example, National Geographic, Nick News and Discovery
Channel have all flown on G-FORCE ONE.
ZERO-G has also been featured on NBC’s The Today Show, Biggest Loser
and The Apprentice.
Apart from commercial flights, ZERO-G also provides research and
educational flights.


Shouldn't the upwash on an airfoil increase the effective angle of attack?

The problem is the true AOA varies depending on where in the flow you measure it.  So what point do you use?  An inch forward of the LE?  Farther forward?  Higher? Lower?

Better to use a consistent value that is independent of the local flow variations in the upwash by using the angle of the chord line to the free stream.


How does an inoperative Anti-Skid affect V speeds?

When you say it affects V speeds, I assume you mean V1 (and possibly VR), but not V2. V1 is usually calculated from the balanced field length, which is where accelerate-stop-distance and accelerate-go-distance are the equal:

(image source: boldmethod > Engine Failure On Takeoff: Do You Stop Or Go?)
While the accelerate-go-distance will be unaffected, the accelerate-stop-distance is affected by anti-skid because you will not be able to brake as efficiently as with anti-skid operating normally:

the antiskid system stops the airplane for all runway conditions in a
shorter distance than is possible with either antiskid off or brake pedal
modulation.
[...]
Braking with Antiskid Inoperative
When the antiskid system is inoperative, the following techniques apply:

ensure that the nose wheels are on the ground and the speedbrakes are
extended before applying the brakes
initiate wheel braking using very light pedal pressure and increase
pressure as ground speed decreases
apply steady pressure and DO NOT PUMP the pedals.

(Boeing 737 NG FCTM 6.45 - Landing, emphasis mine)
As you can see from the above quote, you will increase the stopping distance compared to a normal braking with anti-skid, which results in a larger accelerate-stop-distance, which then reduces the balanced field length V1.
It has nothing to do with the brake energy limitation because the maximum energy that can be absorbed by the brakes is the kinetic energy of the aircraft at the moment you start braking. It does not really depend on how you brake, but with anti-skid inoperative there is a chance that the tires will lock up while decelerating which actually reduces the amount of energy going into the brakes and increases the energy that goes into the tires (in the worst case, this energy will then cause a tire blowout).


Do today's aircraft still have INS (inertial navigation system)?

Short answer
Aircraft still use inertial navigation systems because INS is autonomous, it doesn't need any external support to work, it provides more information, and is more accurate than a GNSS in the short term. There is no plan to stop using it.
On the contrary, INS is required for certain operations. For instance the B787 cannot be flown without at least one IRU operative. See B787 Master Minimum Equipment List MMEL, item 21-01-01 page 182.
The usual solution for air navigation is to use INS, frequently updated by GNSS to contain drift, as long as GNSS signal is available, accurate and reliable (professional GNSS receivers are able to determine their reliability).

GPS/INS sensors fusion, source

Details
While INS has several disadvantages, namely initial alignment time and drift, it has also unique capabilities:

INS is autonomous, position is determined without external cooperative support.

INS position can be updated 1,000 times per second.

INS provides position information like GNSS, but also orientation (attitude), rotation rate and related accelerations. In the short term these data are very accurate. For example, the yaw damper uses instantaneous motion data to counter Dutch roll.

INS provides True North direction.

On the other hand, global navigation satellite systems (GNSS):

Contrary to inertial navigation systems (INS), are dependent on a lot of factors to work, including space vehicles, ground stations, antennas, or solar activity.

GNSS signals can be obstructed, altered or jammed.

GNSS is updated at a slow rate (e.g. once or 10 times per second, that is by increment larger than 20m for an airliner at Mach .85), due to the heavy computation required to extract and process the weak GNSS radio signal.

The best known GNSS, the American Navstar GPS, is a military system funded and managed by US Air Force.

While GPS is in effect always accurate for civil uses, it must be remembered there is no guarantee from the US DoD on that. The Navstar GPS operational specifications for SPS (civil) service allows for 72 minutes per day (2σ / 95th percentile) with a DOP > 3, that is more than 17m horizontally and 37m vertically. During these 72 minutes, the error is unlimited.

In the field of aviation, GNSS and INS are more and more coupled with air data and magnetometers, that's called data/sensor fusion to take the best of each system, cross check results and detect sensor failure.
As a everyday life example: Without an inertial sensor in a car "GPS receiver" (more accurately: a GPS-aided navigation system), the navigation system would be helpless at roundabouts. The GPS receiver instantaneous precision, its low update frequency, and its lack of orientation sensing would prevent it to correctly derives the actual position and the closest roundabout exit.