What is the minimum thrust needed to takeoff?

You need at least enough thrust to keep the airplane flying at the speed of minimum drag. This is quite a bit higher than the minimum flight speed, so you should add something to quicken the acceleration to this point. Also, you want to climb eventually, so you better add some more thrust.

Normally, the static thrust of an airliner is at least a quarter of its weight. If the airliner is empty, this can become as much as half of the weight.

One reason is altitude capability: Since thrust goes down with the density of air, the static thrust in the cruise altitude is only a quarter of sea level thrust. The thrust of a modern high-bypass-ratio engine drops with speed, so at cruise speed and altitude, thrust is roughly a sixth of sea level static.

The second reason is safety: The take-off should be continued even after one engine fails in the late acceleration phase. Now a normally two-engined plane has only half as much thrust available and should still get into the air, so it doesn't crash into whatever follows at the end of the runway.

The thrust needed to sustain flight is about 1/18 of aircraft weight, and if you factor in the multiples given above, you will notice that if the aircraft can fly at full thrust in cruise, this fits nicely with a static sea level thrust force equivalent to one third of its weight force.

The factors for take-off thrust are:

Runway length: Short runways need more excess thrust for faster acceleration.
Runway elevation: Higher places have less dense air, so more speed is needed to get airborne, and less thrust is available from the engines than at sea level.
Runway slope. Taking off downhill is equivalent to having a little extra thrust.
Air temperature: Colder air is denser, so minimum speed is lower and the engines develop more thrust.
Wind speed: A headwind is equivalent to starting the takeoff run at this speed.
Minimum flight speed: A low wing loading and low-drag flap settings reduce the speed at which the aircraft can take off.


What sort of control mechanisms (i.e., PID controllers) do modern FBW aircraft use?

As others have commented, you've underestimated how fast an Intel 80186 found on an early A320 is. Its clock rate is 6 MHz to 25 MHz. While it's very slow compared to what's available nowadays, that's still 6-25 million cycles a second.

The A320's first flight was in 1987, here's what the Air Force Flight Dynamics Laboratory had to say about the subject (Theory of Closed Loop Flight Control Systems) 20 years earlier:

  The electronics field has miniaturized even more so. Microelectronic circuits enable mixing, blending, voting, and, in general, response shaping to be done on a relatively small number of easily replaced cards. Metal oxide semiconductor (MOS) techniques decrease the size of these components by several orders of magnitude. Using these techniques it is now possible to redundacize electronics at a functional module-level with a resulting decrease in size, weight, and cost and a net increase in system reliability.

For modern aircraft, say an A380, we're looking at 40-98 MHz computers:

(Cranfield University, 2016)


Why am I not getting the "TO" VOR flag as I think I should?

A quick review of the US Chart Supplement shows that the Lovelock VOR (LLC) is unusable at your current altitude and position. The VOR is 3.6 NM North by Northwest from the field. Your aircraft is 24.5 NM South by Southwest of the field. Your aircraft would have to be at or above 9600 feet MSL to receive a useable signal from the LLC VOR. This makes any reading you receive from your Nav radio receiver OBS or CDI suspect.

Source: skyvector.com

The probable reason for the VOR indication to work in a sim is that the sim does not replicate real world radio telegraphy. It is only basing the VOR CDI display on geographic position and magnetic variation.
Something of which to take note is the VOR equipment elevation of 4760 feet MSL, versus the highest point Southwest of the VOR at 6348 feet MSL. There is also a microwave tower West of the VOR. These things should be taken into consideration in flight planning.
If you were to use actual IFR charts, routes and procedures, you would notice that you are not allowed to fly below 10,000 feet MSL to still guarantee that you receive the LLC VOR signal on the Victor airway from the FMG VOR to the LLC VOR. As a matter of fact, prior to the HIXUP waypoint, the minimum enroute (IFR) altitude using GPS is 10,300 MSL. The Minimum Obstacle Clearance Altitude of 9500 feet does not guarantee signal reception.

Source: skyvector.com


Is there any U.S. / FAA regulation that could apply for aviation software?

For simulators you have Part 60 of CFR 14

For airborne software the FAA has published AC 20-115, but the main document that refers to is the FAA/EASA RTCA DO-178/ED-12 currently at the "C" version: Software Considerations in Airborne Systems and Equipment Certification.
If you want to certify (and thus commercialize) your software for flight, this is the main document to read.

Depending on the scope of the software and the design/development process there might be different supplements (see here):

  DO-330 Software Tool Qualification Considerations
  DO-331 Model-Based Development and Verification Supplement to DO-178C and DO-278
  DO-332 Object-Oriented Technology and Related Techniques Supplement to DO-178C and DO-278A
  DO-333 Formal Methods Supplement to DO-178C and DO-278A

It has been prepared by the RTCA/EUROCAE joint committee and approved by both FAA and EASA under different names, but the content is the same.

Note that these documents are not freely available.


What is the difference between MIL-H-5606 and MIL-PRF-5606 hydraulic fluid?

About 25 years ago, there was a major effort to revise MIL standards and specifications.  The biggest change in MIL specs was to move away from a design or manufacture spec to a performance spec. The downside of the old specs were that they didn't allow for an improved product without getting the spec revised.  By switching to performance spec (what it must do as opposed to how to make it), improvements can be made without spec revisions and contract revisions (that call out the specs) ultimately saving everyone time and money while delivering products that use up to date technology.

In your case, MIL-H-5606 is the 'old' spec.  The H is taken from the primary application, in this case "Hydraulics".  The current spec is MIL-PRF-5606.  PRF is used to indicate a 'performance' specification.

'MIL-PRF' and other abbreviations are defined within DoD 4120.24-M, [2], Defense Standardization Program (DSP) Policies and Procedures, March 2000, OUSD (Acquisition, Technology and Logistics).


Is Saudia's 777-368ER The Longest Passenger Aircraft?

As far as length is concerned, there are two versions of the 777 classic series, the -200 and -300. The -300 is the longer one, at 242 ft 4 in (73.86 m). Other than choosing one of these two models, there is no customer option to change the length of the plane. I'm not sure where the Saudia data comes from.

But the 777-300 is not the longest plane in the world. The A340-600 previously held that title, at 247 ft 4 in (75.36 m). The 747-8 surpassed this at 250 ft 2 in (76.3 m). The 777-9 may enter service in 2021, setting a new record of 251 ft 9 in (76.7 m).


Human-powered flight in vs. out of ground effect?

Ground effect plays a role when the aircraft is within one wingspan of the ground, so the aerocycle is getting the benefit of lowered induced drag. It looks to be flying about a quarter of a span above the ground, so using the graph that is about two thirds of normal induced drag. Flying out of ground effect would therefore require about 50% more power.


Do multi-engine jets need all engines with equal age to reduce asymmetry in thrust and fuel consumption arising out of deterioration?

It doesn't quite work that way.  When an engine wears out it's rated thrust doesn't decline; its "ITT Margin" (or some similar phrase - basically its thermodynamic margin at takeoff) declines.

When setting takeoff thrust on a turbofan there is a target N1, or target torque on a turboprop or turboshaft, or Engine Pressure Ratio on a pure jet, and the engine has to achieve that target, so it's making rated thrust or power, more or less, no matter how old it is.  What happens when it ages is the temperature required to get there goes up.

There is a maximum hot section temperature  (Inter-Turbine Temperature - ITT or Turbine Inlet Temperature - TIT, or Turbine Outlet Temperature - TOT, or something else, depending on where the probe is) for the engine when producing takeoff thrust or power.  On a new engine, the actual maximum temperature that you will see will be well below the maximum allowable (the temperature margin).

As the engine wears (turbine and compressor blade erosion mostly) and its efficiency declines, what happens is the hot section temperature when the engine is at takeoff rating goes up.  It creeps higher and higher as the engine ages until eventually the margin is gone (or down to some minimum), temperature exceedences on takeoff may start to occur, and it's time to come off.

So there isn't really a thrust asymmetry problem with mixing new and old engines, although there will be a small fuel flow difference, but you have an automatic balancing system to account for this.

Staggering engine times is common.  On an older, heavily depreciated jet especially, the engines may represent a huge part of the value of the airframe and it's a common practice to stagger the age of the engines avoid having to change out two at once when they wear out.


Can an APU be designed to also provide emergency thrust in the event of a double engine failure?

No, it would not be possible with current technology.

To scale the APU to an engine that provides thrust, you would basically have to turn it into another engine, with significant weight penalty. The position of the APU inlet and outlet would have to be re-designed, not to mention mechanisms that allow it to produce variable thrust. In short, it would be turning the plane into a tri-jet.

Furthermore, the chance of a double independent engine failure are slim. If a condition would lead to both engines fail, it would very likely lead to failure of any remaining engines. Converting the APU into a thrust producing device would be a complex engineering exercise with little to no benefit in risk reduction.

Perhaps decades later, we can produce a powerful jet engine using lightweight materials.


What is the correct traffic pattern at a towered airport?

When flying into a towered airport, you will be given specific instructions, as per the ATC Handbook, Section 10, Arrival Procedures and Separation such as:

"make left traffic for runway 15"
"enter a right base for runway 15"
"make straight-in runway 15"

You can also request whatever you want, like: "Tower, Cessna 3-3-Lima, information bravo, requesting left base for 15"," and the controller will then evaluate your request and issue you instructions.

These instructions refer to the following diagram form the Pilots Handbook of Aeronautical Knowledge (PHAK, p. 13-12):

Traffic patterns are also covered in the Pilots Flying Handbook, Chapter 7, and states that:

  When operating at an airport with an operating control tower, the
  pilot receives, by radio, a clearance to approach or depart, as well
  as pertinent information about the traffic pattern.

Which type of traffic pattern information ATC might give you, depends such factors as where you are relative to the airport, other traffic, noise abatement, obstructions, local procedure, etc.  For example, in the diagram below:

N or NE of the airport, you could be given "Left traffic"
NW you could be given a base entry
W you could be given a straight in.
If you're SW, S, or SE of the airport, you could be given the same pattern instructions as the north side, but with RIGHT instead of LEFT, or you could be instructed to overfly the field and enter, say, left downwind.

If you are in contact with ATC, and don't know what you're expected to do, then key the mic and ask the controller.


Are “zero-bag fares” really profitable for airlines?

That's mostly a marketing ploy; people that don't have any bags are more likely to go with a airline that has a no-bag fare.

However not having any checked-in luggage means less overhead in terms of baggage handling as it's a bag less to load and keep track of. It also means that if you got lost and didn't make it to the gate in time they don't have to offload any luggage but can simply pushback as soon as the gate closes.

The freed-up space is then available for non-passenger cargo transport like mail.


I assume you're talking about a light GA airplane (Cessna/Piper singles or twins).

The short answer is "Maybe, but you probably shouldn't.": The parking brake should only be used for as long as necessary to get wheel chocks in, and should then be released.

Aside from making it inconvenient for the local ramp personnel if they need to move/tow your plane, setting the parking brake has a few other downsides which are related to the way the parking brakes work on your typical light aircraft.

When you set the parking brake you're doing two things:

You are pressurizing the hydraulic lines that run to the plane's brakes.
You are doing something to prevent that pressure from bleeding back out.
(Exactly how you accomplish this varies depending on the plane - the "parking brake" on a Piper Cherokee is a tab that prevents the brake handle from returning to the "released" position, maintaining pressure in the cylinder. I think the Cessna 150 pressurizes and then turns a valve.)

Because of how the parking brake works it has two common failure modes when it's set: Pressure can bleed out or it can blow out.

Bleeding Out happens because fittings, seals, hoses, etc. in the brake system aren't perfect. Hydraulic fluid will escape past whatever little opening it can find, and eventually there will be insufficient pressure in the system to keep the aircraft from moving.
If you happened to be parked on an incline steep enough to get the plane rolling it will then go off on its own down the hill just as if you hadn't set the brake (and you will be very confused when you get back to where you left it).

Blowing Out typically happens on hot summer days when there aren't many little openings for pressure to leak out through: 5606 Hydraulic Oil (the stuff in the brake lines) expands as it gets warm, and with the parking brake set it doesn't have anywhere to go (it can't get back to the main brake reservoir). If you land at 11:00 (local time), set the parking brake, and go have a nice leisurely lunch there is a good chance that when you return to the plane at 13:00 or 14:00 you will find that the hydraulic fluid in your brake system has blown out of whatever the weakest point in the system is (often the seals on the toe brake cylinders, sometimes around the calipers, occasionally a hose fitting fails).
This means you're going to have a mess of hydraulic fluid to clean up at best, and at worst if you're on a hill you're in the same situation as above (the plane has gone rolling away), only now there's hydraulic fluid all over as well (sometimes in a little red trail to wherever the plane has wound up).

So bottom line: Try to avoid leaving the parking brake set for extended periods of time, especially if there might be a temperature increase while it's set.
Instead bring your chocks with you (if you own your own plane, or even if you're a renter, pick up a set of "travel chocks" - they're right at or just under 1 pound, you won't even notice them) and chock your wheels when you leave the plane. Ramp personnel will be able to spot the chock easily, and they're unlikely to fail.

Ideally you would also tie the aircraft down if possible, but some ramps don't have tiedowns (and others are bring-your-own-rope).


What Does "By ATC" Mean for an SID Route?

It means, don't file that transition yourself.  ATC may assign it, but it's their option to assign it or leave you on what you filed.


Where to relocate a bomb on a plane to minimize damage?

We covered that stuff during recurrent training and for the CRJ Regional Jets we were told to place it in the forward galley in front of the service door (opposite the main door) and cover with with as much weighty stuff as possible, wet blankets, heavy coats, and such.

You had the mass of the galley to protect the flight deck to some degree, and in theory the explosion would blow out the service door, hopefully leaving the structural frame surround intact, so that overall, it would have the least impact structurally for the fuselage as a load bearing tube with the peak stress just ahead and behind the wings.

In theory... nobody actually believed it would save the plane unless it was fairly small device, but as a calculated strategy to make the best of a hopeless situation, it made sense.

Don't know about other jets, but I would expect that the overall logic is similar.


Why are there 40 737 Max planes in flight when they have been grounded as not airworthy?

Most of them are probably on a ferry flight. The EASA directive allows 1 transfer with up to 3 flight legs without passengers.

Some of them are travelling between countries where they are not grounded.

When a commercial plane crashes, the airline is liable, unless it can prove that the manufacturer is at fault.

I revisited the FlightAware search for B737M today (March 15th), because I was curious how the picture has changed. Same time of the day, just 1 day later:

There is now much less B737M traffic in the US, none in EU, slightly less in Asia, and increased traffic in Africa. That would be coherent with what I answered yesterday, but I was also curious about @Ben's claim that the FlightAware data is not correct. Now this is what I found:

The search in FlightAware identified 26 flights as B38M. Cross checking with FlightRadar24 delivered:

1x 737 MAX 8
18x 737 other than MAX
1x 787-9 Dreamliner
6x not found

The only 737 MAX was - according to FlightRadar24 - AAL9663 from Miami to Phoenix.

I am not sure what exactly FlightAware is showing. My guess is that they are showing the types that are planned to execute the flight.


Why is this plane circling around the Lucknow airport every day?

That is a plane being used to train/practice landings.

It is without passengers and one of the pilots is training. There will also be another pilot on board, possibly two, providing support and checking that the trainee is performing their duties according to the manual.


As SkipMiller said, you can basically request flight following at any time and any certificate level - student, sport pilot, private pilot - the service is available to anyone.

Also:

We're told that FF is "workload permitting".
I used to think that meant they'd give you services when they can.   But I was wrong about that. Instead, once they accept you, you're in the system, and get full services.   If they get too busy, they'll tell you and kick you out of the system.  ("Radar Services Terminated; Squawk VFR")

FF depends on radar services.   When flying rather low and near mountains, its easy for them to lose you.

As for when you should request it:  You can request it at anytime.
Personally, I wouldn't be in a hurry to request it as soon as you depart.   Wait until you're established on course, in a cruise-attitude (instead of a climb), and everything is settled and running smoothly.  Then know your position, and how you're going to report it.  Know where you're going (both by name and ICAO identifier), and try to anticipate any questions they might ask.

Look for the Center/Approach/Depature where you are  (look in your AF/D for an airport close to you), and call up with:

You:   "Seattle Center; November 12345: VFR, with request"
translation:  Calling Seattle Center, this is N12345.  I'm VFR (so you haven't heard from me before... don't be surprised!), and I have a request.

Center:  "November 12345: Say request."

You:  "November 12345 is SkyHawk, 10 mi. South of Harvey Field, 4,500 feet.  Request VFR Flight Following to Friday Harbor"

translation: I'm a Cessna Skyhawk, my location and altitude will help you find me.  I'm asking for FF to this other airport."

Center:  "N345: Squawk 4532 and Ident."

You: (Set your transponder to 4532, press the Identify Button), and say "4532 and Ident, N345"

Center:  "N345: Radar Contact, 11 mi. south of Sierra Four Tree, at 4,500.  Traffic at your 1o'clock, 5 mi. North Bound, Altitude indicates 3,000."

translation:  I found you on my radar scope, and am describing the position I see you. (If you disagree, speak up!).  You have traffic ahead and slightly to your right.  Their transponder indicates 3,000 feet, but I cannot independently verify that.


What happens when auto-pilot fails over the ocean?

As @Bianfable points out in the comments RVSM airspace is a problem but ignoring that for a minute:

The question of will they continue? depends on the airlines op-specs. Different airlines will handle this differently and it may very well be handled different on different airframes within an airline. A call to base may even occur but there are lots of factors that can play into it such as what other equipment is operable.

Assuming the Op-Specs dictate that the flight continues

  how difficult it may be for two pilots to manually fly for this long

Potentially not too difficult at all, most pilots trained in aircraft with no autopilot and all pilots are qualified to hand fly the aircraft. However after Op-Specs it is ultimately up to the pilot and they will consider many factors. Hand flying an aircraft in IMC can be a tiring task for even the best of pilots, a pilot may chose to divert or land sooner if they feel it would be unsafe to continue even if they are capable of flying the aircraft by hand.


Did the contemporaries of the F-14 also have automatic swing wings?

MiG-23
For the MiG-23, it was manual.

[The] MiG-23 had a completely manual wing sweep control. But there was no gauge to indicate optimum wing position for the surrounding conditions. "You had to manually put the wings into position to safely fly the airplane," (...) "They had a very nice gauge that showed where the wings were commanded to, where the wings actually were if they were still in motion, and what the Mach limit was associated with that wingsweep position."
— Red Eagles: America’s Secret MiGs p.176

From Wikipedia we learn the sweep steps were 16°, 45°, and 72° – for one of the variants at least – which makes it easy to find that gauge. Here it is magnified below with the limiting Mach number (M2.35) and Velocity (1400 km/h indicated; 756 KIAS) for the current selected max sweep of 72°.

(worldwarwings.com)
Su-17/20/22
It started as a two-position wing, then it was upgraded1 so that the wing can stop anywhere between 30° and 63°. This improved the flight range.
Below, КРЫЛО means wing. And ОТКЛ means off, or deactivate (ОТКЛЮЧИТЬ). This leads me to conclude it too was manual despite the advanced avionics the Su-17 family carried.

(primeportal.net) The wing control switch and position indicator are on the left glareshield.

1 Source: Polish Wikipedia
Bonus: YouTube video showing the pilot using that switch


What is the reason to have LOC/VNAV landing method?

A VNAV with localiser approach is normally a backup to a regular ILS should there be a glide slope unserviceability. The use of VNAV  to manage the vertical portion of the approach would allow the use of APV minima which are normally lower than using a vertical speed mode.

VNAV is a better mode when conducting non-precision approaches as the aircraft is still following a defined glideslope - albeit derived from a database - which is more accurate than trying to follow a tabled set of heights and distances using vertical speed.


Could the reversers of a PW4000 on a 777 be deployed in-flight?

A basic requirement of certification is the probability of any single point of failure that causes loss of the airframe (hazard level = catastrophic) must be better than 10 -9, or one in a billion.  A reverser deployment in flight would meet that level of hazard so system design has to meet that probability level.

In the case of Lauda Air, I would have to assume Boeing made a mistake in the system architecture that allowed a one in a billion event to happen "prematurely", and in fact they introduced a design change to get back to the required probability level.  In the case of the 777, or any other airliner, you have to assume the homework was done properly and the architecture meets the requirement until an event indicates otherwise.

Most of the time, gaps in design redundancy turn up during in-service events that are not as nasty, but that set off alarm bells at the OEM as potentially something more serious, and after a long process of analysis of risk and design, changes are implemented in the field by Airworthiness Directive.

It seems cold and calculating, but the whole thing is a numbers game where people with pointy hats with stars and crescents on them work out probabilities, of risk of death basically, using arcane methods like weibull analysis, to decide what to do and how soon to do it when design flaws turn up.  The transportation system couldn't function without it though.

Anyway, it's safe to say the risk of a reverser deployment in flight on a 777 is microscopic, but it's not zero, as nothing is in aviation.


What should a pilot flying IFR in IMC and on final, do if the vacuum system fails?

Your scenario isn't really realistic, the turn coordinator and the AI are almost always on different sources of power to protect against this very event. The TC is almost always electrically driven because it gives an alternate source of information.

A loss of an instrument or even a whole suite of instruments is something instrument rated pilots train for, and should practice once they have their rating. We call it partial panel, where you use your other instruments to make up for the loss. If you lose your vacuum driven instruments you fall back on your electrical and non powered instruments like the altimeter, airspeed gauge, VSI and magnetic compass.

Addressing your question, if I experienced a loss of vacuum on short final when I was established on an instrument approach I would most likely simply continue the approach and land. A loss of vacuum doesn't immediately cause those instruments to keel over and die, they keep working for awhile, getting less accurate as they spin down. Heck, if I'm on a short final I may not even recognize the failure!

If I'm on a longer final and I lose my vacuum powered instruments I would also continue the approach unless there was alternative with better conditions or less hazards nearby. Your vacuum instruments aren't going to fix themselves, so there's no point in flying around waiting for something else to go wrong.

The exact situation you describe in your question would be extremely unusual to say the least, this would most likely be caused by something pretty catastrophic that would mean continuing the approach is impossible. If I had a total powered instrument failure but somehow my ILS and radio stayed up I would continue the approach using the residual momentum of the gyros to keep situational awareness as long as possible, then fall back to my working instruments. I'd also declare an emergency, and ask for ATC to give me surveillance radar data, they can give me a running commentary of which direction I'm turning.

Of course, if it was me I'd activate emergency AI app I have on my tablet GPS or my phone. Both use the phone/tablet sensors to produce a pretty reliable picture.


What is this aircraft with elaborate folding wings?

Fairey Gannet ECM.6, c/n F9311, stored at White Waltham Airfield in the county of Berkshire in England. This place is incidentally where the Fairey Aviation Company built and test-flew the Gannet. An aerial picture from Google Maps:

Farey Gannet XA 459 at White Waltham Airfield. Google Maps
In Feb. 2020 the aircraft was Finally moved to Solway Aviation Museum to be heavily restored for public display.
The wings can be folded in order to park the aircraft on a carrier deck, or on its storage areas. Unfolding the wings (video).

Fairey Gannet ECM.6
Fairey Aviation was a manufacturer which worked a lot with the British Royal Navy's Fleet Air Arm (FAA). With the role played by German and Japanese submarines during WW2, the FAA reinforced its anti-submarine warfare. Fairey Aviation developed the carrier-borne Type Q, later renamed Gannet version AS.1 quickly upgraded to a more powerful AS.4.

Fairey Gannet AS.4. Source
The prototype first flew on 19 September 1949 and made the first deck landing ever by a turboprop aircraft, on HMS Illustrious in June 1950. The anti-submarine role was later taken by helicopters, and AS.4 versions were converted for electronic countermeasures (ECM.6). A third seat was later added over the wing trailing edge for a second observer. This disturbed the airflow over the horizontal stabilizer, requiring the addition of small finlets:

Fairey Gannet ECM.6 with three seats. Source: Gothic-Air

Fairey Gannet landing on Australian HMAS Melbourne. Picture David Tomkinson, source
The Fairey Gannet was powered by a dual Armstrong Siddely Mamba, driving two contra-rotating propellers. One engine could be shut down in flight to conserve fuel if required.
XA 459 RN
A total of 348 Gannet were built, this particular airframe is c/n F9311 registered XA 459 RN for the Royal Navy. It entered 814 NAS in March 1957 as AS.4. Here at RNAS Culdrose in 1976, after it was converted into ECM.6:

Fairey Gannet ECM.6 at RNAS Culdrose, 1976. Photo by Ray Barber at flickr
The aircraft was decommissioned in 1978 and later displayed at Wales Aircraft Museum (Cardiff EGFF):

Fairey Gannet ECM.6 at Wales Aircraft Museum, 1982. Photo by Chris England at ABPic
The museum was disbanded in 1996. The Gannet was then acquired by private individuals in order to restore it. However tragical events prevented the restoration. It was finally bought by White Waltham airfield in 2006.

White Waltham from 2006 to Feb. 2020

XA 459 at White Waltham. Photo by Renegade53 at ipernity

XA 459 at White Waltham. Photo by Jon Wickenden at Flicr
Ian Meredith told us in February 2020 the Gannet was moving to a new place:

Tonight the Gannet and its spare engine(s?) was aboard a low loader
for a UK museum. A place of restoration, a place in the dry.

This place is the Solway Aviation Museum at Carlisle Lake District Airport. On the move:

Fairey Gannet XA 459 moving to its new place, Feb 2020. Source.
Solway Aviation Museum since 2020
Video of its arrival

More about the aircraft:

Exhaustive description of the Fairey Gannet: Alchetron
Pictures: Fleet Arm Association of Australia
Pictures: Flickr
History: Stephen Metcalf's page
History: South Wales Aviation Group


Does a GPS OBS selector use magnetic or true courses?

Magnetic, except for places on Earth where it would be truly ridiculous (such as high latitudes).

Basically, you want to navigate with one reference or the other, no matter which method you are using, to avoid confusion. Using magnetic reference is somewhat of a legacy: it's natural to use it when your primary method of navigation is a compass. Or even not a primary: stars and INS are referenced to True, but the pilot should be able to fall back on the compass at any moment (and cross check the instruments), so a correction (= variation) is always maintained.

GPS naturally works in True coordinates. But to provide 'backward compatibility' it also calculates Magnetic track. To do that, the avionics must maintain a current database of magnetic variation across the globe.

Furthermore, remember that GPS cannot really measure the heading, it can only measure the track. Heading is still measured using gyros, which are periodically corrected using magnetometer, i.e. the same compass.

Modern avionics can be switched between Magnetic and True references (see, for example, the G1000 guide). So technically the answer to your question would be 'it depends on the mode', but usually it is expected to be Magnetic.


What's the point of separating the Alternator and Battery switches?

I will expand a bit on @Noah Krasser's answer with some situations where you would want one or the other. FWIW under-volt scenarios are typically far less of a problem than over-voltage scenarios.

Bad Voltage Regulator: Alternators vary their voltage output with RPM. To keep your system operating properly a voltage regulator is installed on the alternators direct output. This keeps your systems power supply at a constant voltage, typically at the cost of some power in the lower end. These things can and sometimes do fail, if they fail in such a way that the alternator is at a high RPM and putting out a voltage that could be potentially harmful to your avionics you are going to want the ability to cut it off while still drawing from your battery.
Battery Short: More often than not batteries are stored in the tail section of GA planes or potentially anywhere. If the cable chase leading to the battery develops a short you may want the ability to cut the battery circuit out while still having the ability to power you aircraft from the alternator.
Thermal Runaway: Batteries can runway on you and cause an over-volt issue. Again in flight you are going to want to be able to cut it from the system.


Can I get a sport pilot license while taking Mirapex?

Assuming you have never applied for a medical certificate:

You need to ask your doctor. Sport pilots don't need to have a medical certificate, but they do need to be capable of operating an airplane safely. Mirapex is on the do not issue, do not fly list, so the presumption is that you cannot fly while taking it. In order to legally fly solo or with passengers while taking Mirapex, your doctor must tell you that it's safe to do so.

Your doctor may tell you that it's not safe to fly while taking Mirapex. In that case, you only have two options: stop taking the medication (with the approval and supervision of your doctor), or don't fly (except as a student receiving instruction).

If you have applied for a medical certificate ever in your life: You need to get a medical certificate in order to fly solo or with passengers. In this case, you need to talk to an aviation medical examiner for advice; there's no way around this.


Are there any programs to build a hydrogen powered airplane?

Aviation is very energy-hungry. While hydrogen is quite efficient in terms of energy per mass (141.8 MJ/kg), it is awful in terms of energy per volume. Aircraft today use their wings for fuel storage, which helps to reduce bending loads and uses a volume unsuitable to transport payload. This will not work for hydrogen.

The biggest problem is storage, and none of the solutions is really attractive:

Cryogenic: Storing the hydrogen at a temperature where it is liquid (below 20°K) greatly reduces volume demands, but now you need to add insulation, and even then the energy per volume is only a quarter compared to hydrocarbons. This is used in rockets, because they can rely on extensive ground support before launch and use up the stuff in a few minutes. Airliners, however, need to store their fuel over tens of hours, so their hydrogen tanks will be much heavier and bulkier than those of rockets.
Compressed: This avoids the energy input for liquefaction, but now you need a strong and heavy pressure vessel. Current gaseous hydrogen storage uses up to 700 bar pressure, but even then the volume demand is six times higher than that of kerosene for the same energy content.
Hydrides: Some metals like magnesium or sodium can bind hydrogen and release it when heated. However, even in the most efficient compounds like sodium tetrahydroaluminate, only 7.4% of mass is useable hydrogen, making this exquisitely unsuitable for mass-critical applications like aviation.

Currently a mixture of cryogenic and compressed storage looks the most attractive and has been tested widely.

The first (partially) hydrogen powered aircraft was the LZ-127 Zeppelin which used a mixture of gasses of equal mass per volume as air (Blaugas) to power its engines.

Tupolev designed and flew the Tu-155, the first hydrogen-powered heavier-than-air aircraft, in 1988. The results showed that the principle worked, but could not compete with kerosene.

Currently, several demonstrators are in operation, but none with the hope of widespread application - as it stands, binding hydrogen chemically to carbon will still give the best way of storage (liquid and unpressurized) for aviation.

Hydrogen becomes the best source of energy only when combustion speed is critical, such as in supersonic combustion ramjets (scramjets).


Both are different ways to express the boundary layer thickness in a deterministic way.

The boundary layer according to wikipedia:

  a boundary layer is an important concept and refers to the layer of fluid in the immediate vicinity of a bounding surface where the effects of viscosity are significant.

Since there can be debate about what significant means, multiple formulations for the boundary layer thickness exist. And depending on the problem to solve, one of them can be more suitable than the other.

Therefore the boundary layer thickness is by typically specified as the distance where the velocity reaches 99% of the free stream velocity.

The boundary layer momentum thickness can be exactly specified as the distance a uniform flow field should be displaced by to equal the total momentum flux (m*v)*v of the real boundary layer (non-uniform).

There is also the boundary layer displacement thickness, comparing the mass flux deficit (m*v) rather than the momentum flux deficit (m*v)*v, as highlighted by the slides in Juan Jimenez's comment.

Take a look at this quora answer as it contains good explanatory figures.

Update:

I found a paper with comparative figures of the displacement and momentum thickness based on XFOIL results. It's worth to take a look at. Iliev, Sergiu. (2016). Aerofoil Analysis using XFOIL - Practical Implementation for Preliminary Wing Design. 10.13140/RG.2.2.30861.54243.

An example of where displacement and momentum thicknesses are useful can be found in the XFOIL documentation.
The displacement thickness can be used to couple a boundary layer solver with a potential flow solver (ISES code).
XFOIL uses the momentum thickness to calculate the viscous drag.

  Viscous Formulation

  The boundary layers and wake are described with a two-equation lagged
  dissipation integral BL formulation and an envelope e^n transition
  criterion, both taken from the transonic analysis/design ISES code.
  The entire viscous solution (boundary layers and wake) is strongly
  interacted with the incompressible potential flow via the surface
  transpiration model (the alternative displacement body model is used
  in ISES).  This permits proper calculation of limited separation regions.
  The drag is determined from the wake momentum thickness far downstream.
  A special treatment is used for a blunt trailing edge which fairly
  accurately accounts for base drag.


Why are swept wings better for breaking the sound barrier?

It's all about the 'effective' Mach number that the wing sees.  In essence, for a swept wing, the Mach number that the wing 'sees' as far as compressibility effects are concerned is the Mach number of the component of the freestream normal to the wing chord:

(Source: stanford.edu via archive.org)

By sweeping the wing back, you can get closer to the speed of sound without getting supersonic flow over the wing (remember, a wing generates lift by accelerating the air flowing over it, thereby decreasing the pressure - so you'll get supersonic flow over the wing before the freestream is supersonic).  Of course, once you fly supersonic, there's really no getting around having shock waves over the wing - however, you can reduce their strength with wing sweep.


Why is white light more visible than red and green on this Cessna model on a sunny day?

The navigation lights are meant to give away the airplane's orientation (i.e. which direction it is travelling) at night. The red and green lights are small. Their purpose is to be observable from a long distance, which only requires a small light. For the same reason, the anti-collision red lights of tall structures are small as well.

The landing lights (white light) are meant to illuminate the runway, taxiway or any terrain in front of the aircraft. The light must travel to a certain distance in front of the aircraft then bounce back. They are very bright. To experience that, go to a busy airport at night and stand near the approach end of a runway. In fact, standing next to an airliner with its landing lights fully on would likely damage your eyes.

Landing lights must also be turned on when any aircraft enters an active runway. Here they serve the same purpose of turning on the headlights of your car at night: to make sure others can see you. This regulation came after an airliner landed on an occupied runway at night. It was determined that the plane on the ground blended in with the runway lights, and the pilots of the landing aircraft were unable to spot it. Had the plane turned on its landing lights, the very bright light source would have give away their position and alerted the crew to abort its landing.

The model is simply a replica of the real life scenario.


How does email communication with a private pilot affect FAA rules on compensation?

I'll answer it from the FAA since that's what I know.

The FAR is pretty clear on the matter here

  (a) Except as provided in paragraphs (b) through (h) of this section, no person who holds a private pilot certificate may act as pilot in command of an aircraft that is carrying passengers or property for compensation or hire; nor may that person, for compensation or hire, act as pilot in command of an aircraft.

However if you want to split the cost evenly, you can:

  (c) A private pilot may not pay less than the pro rata share of the operating expenses of a flight with passengers, provided the expenses involve only fuel, oil, airport expenditures, or rental fees.

For what it's worth I would say you can still operate under Part 91 in the case you have outlined.

Basically the FAA prevents a PPL holder from receiving any kind of compensation for a flight. This Article talks about some of the points that the FAA discussed when shutting down these services. The issue with some of these sharing services is that the middle man (AirPooler) and the like take a fee, this seems like the aspect that the FAA had an issue with since although the pilot was not profiting per se, someone was, this seems to be the FAA trigger. I don't know much about the deep aspects of the law but I'm sure there are things that can also arise with being a middleman/deal broker of these kinds of things.


What is the standard rate of turn for heavy aircraft?

I'm only able to find the following about bank angles, which specifically refers to turns while in a holding pattern:

AIM 5-3-86.(b):

  (b) Make all turns during entry and while holding at:

  (1) 3 degrees per second; or

  (2) 30 degree bank angle; or

  (3) 25 degree bank provided a flight director system is used.

  NOTE-
  Use whichever requires the least bank angle.

This is also in the Instrument Procedures Handbook which under *High Performance Holding on page 3-25 says that a flight director has a bank angle limit of 25 degrees.

If we use the above guidelines, then a flight director will use 3 degrees per second or 25 degrees of bank, whichever is less.  My calculations give us the following bank angles and associated rate of turns1:

        Standard Rate      Actual        Rate
TAS      Bank Angle      Bank Angle     of turn
80         13.17           13.17         3.00
120        19.34           19.34         3.00
160        25.08           25.00         2.99
200        30.33           25.00         2.39
240        35.07           25.00         1.99
280        39.31           25.00         1.71
320        43.10           25.00         1.49
360        46.48           25.00         1.33
400        49.48           25.00         1.20
440        52.15           25.00         1.09
480        54.54           25.00         1.00

As you can see, a jet travelling at 480 Knots TAS (not uncommon at altitude) would require almost a 55 degree bank angle to make a standard rate turn, which would be an amount considered by almost anyone as excessive.

When limited to 25 degrees of bank, this would result in a rate of turn of 1 degree per second (or a 6 minute turn).  Anything over 160 Knots TAS would be less than a standard rate turn, and once past 320 Knots TAS it  wouldn't even be a 1/2 standard rate turn.

As far as the 1/2 Standard Rate, they often use the 1/2 BANK autopilot mode at high altitudes.  This would result in a rate of turn approximately halved, so a 360 degree turn would take 12 minute at the same 480 Knots TAS.  ATC expects the normal bank in the terminal environment though, so it isn't used at lower altitudes.

As others have said, transport category jets don't even have a rate of turn indicator (it isn't required by 14 CFR 25 if you have a third attitude indicator) and they simply fly bank angles.  Normal hand flying is limited to 30 degrees, which would allow a standard rate turn at a slightly higher airspeed, but then starts to taper off just the same.

That being said, the Instrument Flying Handbook does include this little tidbit in the section on turn indicators on page 5-21:

  The dial of these instruments is marked “2 MIN TURN.”  Some
  turn-and-slip indicators used in faster aircraft are  marked “4 MIN
  TURN.” In either instrument, a standard  rate turn is being made
  whenever the needle aligns with a  doghouse. A standard rate turn is
  3° per second. In a 2 minute  instrument, if the needle is one needle
  width either side of  the center alignment mark, the turn is 3° per
  second and the  turn takes 2 minutes to execute a 360° turn. In a 4
  minute  instrument, the same turn takes two widths deflection of the
  needle to achieve 3° per second.

So maybe at some point in the past it was more common (or maybe faster but-not-quite-as-fast-as-todays-jets) but you just don't see that anymore.  (It could be where all of the references to 1/2 standard rate turns come from though.)

1 Math adapted from the formulas here.


What does the preliminary report on the Ethiopian B737 MAX accident show?

In the short summary, the preliminary report (33-page PDF available here) gives these details:

  Shortly after takeoff, the Angle of Attack sensor recorded value became erroneous and the left stick shaker activated and remained active until near the end of the flight. In addition, the airspeed and altitude values from the left air data system began deviating from the corresponding right side values.

Among the few initial findings, the preliminary report has these:

  Shortly after liftoff, the value of the left angle of attack sensor deviated from the right one and reached 74.5 degrees while the right angle of attack sensor value was 15.3 degrees; then after, the [left] stick shaker activated and remained active until near the end of the flight.
  After the autopilot disengaged, the [Flight Data Recorder] recorded an automatic aircraft nose down (AND) trim command four times without pilot’s input. As a result, three motions of the stabilizer trim were recorded. The FDR data also indicated that the crew utilized the electric manual trim to counter the automatic AND input.

In the section giving details derived from the Flight Data Recorder and Cockpit Voice Recorder, the following items are included:

  At 05:40:00 shortly after the autopilot disengaged, the FDR recorded an automatic aircraft nose
  down (AND) activated for 9.0 seconds and pitch trim moved from 4.60 to 2.1 units. The climb was
  arrested and the aircraft descended slightly.
  At 05:40:03 Ground Proximity Warning System (GPWS) “DON’T SINK” alerts occurred.
  The column moved aft and a positive climb was re-established during the automatic AND motion.
  At 05:40:12, approximately three seconds after AND stabilizer motion ends, electric trim (from
  pilot activated switches on the yoke) in the Aircraft nose up (ANU) direction is recorded on the
  DFDR and the stabilizer moved in the ANU direction to 2.4 units.

A second similar sequence (automatic nose down trim, “DON’T SINK” from GPWS, and pilot-commanded electric nose up trim) then occurred from 05:40:20, to 05:40:28.

The diagram below, from a report appendix, shows aircraft pitch related data from the FDR from the first automatic nose-down to the end of the recording.  (Time advances from left to right.)

  At 05:40:35, the First-Officer called out “stab trim cut-out” two times. Captain agreed and FirstOfficer confirmed stab trim cut-out.
  At 05:40:41, approximately five seconds after the end of the ANU stabilizer motion, a third instance
  of AND automatic trim command occurred without any corresponding motion of the stabilizer,
  which is consistent with the stabilizer trim cutout switches were in the "cutout" position.
  From 05:40:42 to 05:43:11 (about two and a half minutes), the stabilizer position gradually moved
  in the AND direction from 2.3 units to 2.1 units. During this time, aft force was applied to the
  control columns which remained aft of neutral position. The left indicated airspeed increased from
  approximately 305 kt to approximately 340 kt (VMO). The right indicated airspeed was
  approximately 20-25 kt higher than the left.
  At 05:41:46, the Captain asked the First-Officer if the trim is functional. The First-Officer has replied
  that the trim was not working and asked if he could try it manually. The Captain told him to try.
  At 05:41:54, the First-Officer replied that it is not working.
  At 05:43:11, about 32 seconds before the end of the recording, at approximately 13,400 ft, two
  momentary manual electric trim inputs are recorded in the ANU direction. The stabilizer moved in
  the ANU direction from 2.1 units to 2.3 units.
  At 05:43:20, approximately five seconds after the last manual electric trim input, an AND automatic
  trim command occurred and the stabilizer moved in the AND direction from 2.3 to 1.0 unit in
  approximately 5 seconds. The aircraft began pitching nose down. Additional simultaneous aft
  column force was applied, but the nose down pitch continues, eventually reaching 40° nose down.
  The stabilizer position varied between 1.1 and 0.8 units for the remainder of the recording.
  The left Indicated Airspeed increased, eventually reaching approximately 458 kts and the right
  Indicated Airspeed reached 500 kts at the end of the recording.

The "automatic aircraft nose down" events mentioned in the above can be ascribed to the MCAS (Maneuvering Characteristics Augmentation System), which Boeing only started informing pilots about in late November, 2018.


Has there ever been a diesel-electric helicopter?

Helicopters currently use lightweight but fairly inefficient gas turbines. Diesel-electric engines have great energy efficiency, in terms of mechanical energy delivered per kilo of fuel. However, they're quite heavy. This means that you need more lift, which in turn means more power is needed. This negates the initial advantage.

With the advent of lightweight materials, the latter effect decreases so this situation might change.

Diesel engines can throttle up and down quite a bit, unlike gas turbines,  but this capacity is irrelevant to helicopters. Note that helicopters need a pretty constant amount of lift.


Identify a balloon accident in the 90s or 2000s

P 15 of this link describes an incident on July 20 1990 where an unmanned scientific balloon project accidentally experienced a freefall of the payload from 120,000'.  Any chance that what you are remembering was this, or something similar?

http://hdl.handle.net/2060/19910006317

  The 1990 calibration actually consisted of two flights,
  one on July 20, 1990 and the other on September 6, 1990.
  A malfunction occurred during the first flight, which
  resulted in a complete loss of data and a subsequent free fall
  of the payload from _ 120,000 ft which bent up the tracker
  assembly and destroyed several cell modules. The tracker
  was rebuilt, several cells were replaced, and the refurbished
  payload was flown again in September.


What does Alternate NA mean on an approach plate?

That symbology means this approach cannot be considered when deciding if this airport is a suitable alternate.  This is probably due to the lack of weather reporting or the navaid might not have the required monitoring.  This means the availability of the approach cannot be guaranteed and so you can not rely on it as an alternate.

To file TTA as an alternate you must comply with the the non-standard alternate minimums and you must be legal and equipped to fly either the RNAV (GPS) RWY 03 or RNAV (GPS) RWY 21 procedures.  If the ILS Y RWY 03 is available when you get there, you may fly that procedure instead of the RNAV procedures, you just cannot file it as an alternate on the basis of the ILS.

The wording in the Terminal Procedures legend (PDF) is

  Alternate minimums are Not Authorized due to unmonitored facility or absence of weather reporting service


What is that invisible bump in the air called that occurs after completing a 360 degree turn?

It's your aircraft's wake, as in wake turbulence.


Do gyroscopic forces (from rotating engines) significantly affect yaw or pitch?

Yes. The more so the higher the inertia and speed of the rotating masses and the lower the control authority. While the gyro forces of a jet are negligible in regular flight due to the high damping provided by the wings and tail, in hover they can become dominant. The Bristol-Siddeley Pegasus engine of the Kestrel, Harrier and AV-8B jump jets needs to have the low pressure spool run in opposite direction of the high pressure spool to balance its gyro effects. If that would not be the case, a yawing motion would produce a pitching motion, and vice versa. When you sit on a jet, the thrust of which is equivalent to your weight, tilting this jet fore or aft only slightly will produce a quick shift of your location, so any maneuvering in hover will become extremely hard.

USMC AV-8B Harrier in hover (picture source, © Richard Seaman 2001)

Generally, contra-rotation of engine parts has been used to reduce gyro effects. They first became an issue with rotary engines in WW I. A rotary engine has its crankshaft fixed to the airplane, and both the cylinder block and the propeller rotate. This gives better cooling at low speed and produces a flywheel effect, so the engine runs more smoothly. But when you yaw, the gyro effect pitches the aircraft up or down, so any precise maneuvering becomes very hard.

With the increasing engine power in 1916 and 1917, this effect became so severe that geared engines were developed where the cylinders rotate in one direction and the propeller in the opposite direction. As a consequence, the propeller had only half the RPM in air as it had with the cylinder block. This resulted in great propeller efficiency, but also big propeller diameters, so airplanes with those engines needed a high landing gear. Below is a picture of a Roland D XVI with a Siemens & Halske III contra-rotating rotary engine from 1918. This was an excellent fighter aircraft for its time with almost no gyro coupling.

Roland D XVI (picture source)

Generally, jet engines are sensitive to maneuvering: Changing load factors will bend the spools between their bearings such that the tip clearance of both the turbine and the compressor need to be big enough to avoid contact under g forces, or when rolling with a wing-mounted engine. Every engine manufacturer will publish a load factor envelope within which the engine is safe to operate. Widening this envelope will reduce engine efficiency because the gaps between the rotating parts and the engine housing need to grow with the maximum load factor.


What are the effects of the tilted lift vector in a banked plane?

In a banked turn under cetripetal force, what causes the change in the heading of the plane such that its longitudinal axis remains facing the relative wind?

The simplest case of a flat wing will create lift orthogonal to its direction of motion and the direction of wingspan, and some drag parallel to its direction of motion. Both lift and drag will act in the plane of symmetry. Let's assume that drag is compensated by a constant thrust, so the level wing is in equilibrium. A tilt will contribute a sideways lift component that is not compensated by weight and will accelerate the wing sideways.

This will move the wing into the direction of lift and reduce its angle of attack. Lift will drop which reduces sideways acceleration. Unfortunately, this also means that gravity will not be fully compensated. The wing will be accelerated downwards which increases its angle of attack. Both effects will settle at a point where the wing moves side- and downwards, the sink speed depending on the drag increase since more lift in total must be generated.

But the picture is incomplete without the contribution of the tail surfaces. The sideways motion will cause a side force on the vertical tail which will weathervane the aircraft into the direction of sideslip. Only that lateral stability contribution will start the turning motion. Now you get a continuous process in which the wing accelerates the whole airplane sideways and the tail will yaw it into the wind, resulting in a not well coordinated turn. The yawing motion will add a centripetal acceleration which will eventually balance the sideways acceleration from the tilted lift force.

Since we decided to leave thrust constant, the added lift requirement will cause more drag and the aircraft will sink in order to compensate for the energy loss from turning. If we now add the freedom to change the elevator deflection, we can trim the aircraft for the higher lift and a lower speed so that (depending on the position of the initial state on the power curve) the aircraft could fly a level turn at a lower flight speed.

I also neglected pitch stability so far. At higher bank angles it becomes important and contributes to the turn in proportion to the sine of the roll angle. With a constant elevator deflection, pitch stability will try to keep speed constant and pitch damping will reduce the turn rate. Once we allow to adjust the elevator, pulling will reduce pitch damping and trim a higher angle of attack, so the turning rate will pick up.


Is it possible to get permission to fly a quadcopter around the St. Louis Arch for non-professional means

The Superintendent's Compendium for Gateway Arch National Park says

  Launching,  landing,  or  operating an  unmanned  aircraft  (UA)  from  or  on lands  and waters administered  by  the  National  Park  Service  within the  boundaries  of  the Jefferson National Expansion Memorial  is  prohibited  except  as  approved in  writing by  the  superintendent.

Since drone flight is not listed under activities that require a permit they clearly don't approve such activity on a regular basis. The only way I imagine they would approve non-commercial activity is if there was some sort of organized event. On an individual basis I expect the answer would be no.


Any aircraft, from a helicopter to a 747, can soar.

All it has to do is enter and maintain its position in rising air. How the pilot accomplishes that would be based on picking a strategy for staying in the rising air, and using his skill to do it.


Does a request for a Pop-Up IFR clearance constitute filing a flight plan?

I think Porcupine911 nailed the first question perfectly with the reference to JO 7110.65W: A "pop-up" IFR clearance counts as filing an IFR flight plan.
ATC considers it an "airfiled" flight plan (VFR-to-IFR), and the controller talking to you will take at least the bare minimum information necessary to enter you into the ATC system and generate a flight plan / strip for your aircraft.

Your second question is a little more complicated, but the short answer is that pop-up IFR clearances aren't "tacit authorization to omit information required by 91.169", but controllers are busy people and don't have time to key all that into the computer when they're supposed to be working traffic.

The longer version is that what you probably should be doing to get an IFR clearance in-flight is calling the local flight service station over the radio and air-filing your IFR flight plan with them, then checking in with ATC (who will have all the information Flight Service took from you and entered into the computer, without having to tie up their frequency interrogating you for it).

The FAA (or at least the ATC organization) is not without a heart though: They understand that if you're calling them for a pop-up IFR clearance it means you're in a bit of a situation (like IMC closing in on you with no good "out" that will allow you to remain VFR) and you need to get into the system before you hit the ground, a building, or another aircraft.
Giving the controller the bare minimum skeleton of a flight plan allows them to get you into the system and under positive ATC control to ensure you're operating at a safe altitude without any traffic conflicts, which satisfies the first of the three ATC operational criteria ("Safe") -- the other two (Orderly & Expedient) are a lower priority and can be dealt with later.


What is the minimum turning radius of an SR-71?

The Turn Radius of the SR-71 would depend on its speed. The faster it went  the wider its turn radius was.

The SR-71 had a minimum turning radius at altitude of about 80 nautical miles (NM) . It was not an airframe limitation but a matter of wing area. At 80,000ft, the air is too thin and the wings too small to allow for much lift to turn with.

At a turn radius of 80 NM, the SR-71 would cover about 145 miles, taking about 4 minutes in the process of making a 180 degree turn.

Details are provided in the SR-71 flight manual handbook, which is now declassified:


What does "radar contact" mean in ATC calls?

The FAA's Pilot/Controller Glossary gives both US and ICAO definitions:

  RADAR CONTACT- a. Used by ATC to inform an aircraft that it is identified on the radar display and radar flight following will be
  provided until radar identification is terminated. Radar service may
  also be provided within the limits of necessity and capability. When a
  pilot is informed of “radar contact,” he/she automatically
  discontinues reporting over compulsory reporting points. [...]

  b. The term used to inform the controller that the aircraft is
  identified and approval is granted for the aircraft to enter the
  receiving controllers airspace. (See ICAO term RADAR CONTACT.)

  RADAR CONTACT [ICAO]- The situation which exists when the radar blip
  or radar position symbol of a particular aircraft is seen and
  identified on a radar display.

  RADAR CONTACT LOST- Used by ATC to inform a pilot that radar data used to determine the aircraft’s position is no longer being
  received, or is no longer reliable and radar service is no longer
  being provided. The loss may be attributed to several factors
  including the aircraft merging with weather or ground clutter, the
  aircraft operating below radar line of sight coverage, the aircraft
  entering an area of poor radar return, failure of the aircraft
  transponder, or failure of the ground radar equipment.

Note that this is not a universal term, Canada uses "radar identified" instead. Their equivalent of the P/CG is the Glossary for Pilots and Air Traffic Services Personnel:

  “Radar identified”

  An expression used by ATC to inform the pilot of an aircraft when radar identification is established.

  Fr: « Identifié radar »

And:

  “Radar contact”

  U.S.: Expression for: “Radar identified”


Why do swept wings decrease the drag increase that occurs in transonic flows?

Shock waves form where air can no longer "get out of the way" and begins to compress.

Sweeping the wing effectively increases the chord and reduces the rate of wing thickness increases as airflow moves across it, essentially making the body longer and more "streamlined". Instead of running into a steep hill and compressing, it can flow over a more gently sloping barrier with greater ease.

What is most interesting is the decreasing drag of the 47 degree sweep at high subsonic.  As sweep increases, airflow over the wing may transition from the classical front to back flow seen in straight wings to the deflected "spanwise" airflow of swept wings to the rolling vortices seen in highly swept "slender delta" wings.

At some combination of speed and sweep, airflow will roll up into a vortex rather than washing off the back or end of the wing.  It may be that, at higher subsonic speeds,  with greater sweep, the vortices roll into the back of the wing and push the aircraft forwards.

It has been thought the same thing occurs underneath thin undercambered wings, which may help account for some of their "magical" slow flight properties.  Definitely worth studying.

As far as 11, and 35 degrees of sweep, they follow predictable patterns based on compression effects at transsonic speeds, as does the Area Rule.

Are swept wings better for breaking the sound barrier?  Not really, as the X-1 proved.  But they do significantly delay transsonic drag at high subsonic speeds.


What are the main sensor value that cause High pressure compressor fault in turbofan engine?

It sounds like you are looking for an understanding of how the HPC efficiency affects the overall engine performance.  My suggestion here would be use NASA's excellent engine simulator: https://www.grc.nasa.gov/www/k-12/airplane/ngnsim.html  One of the many variables that you can play around with is HPC efficiency.  Note that as you decrease HPC efficiency, overall EPR is going to drop.  In a real engine, the controller will notice this and dump in more fuel to compensate and get back to the original EPR.  In this simulator, you will have to do that by adjusting the throttle controller.

Here's a screenshot of the engine simulator running.  The one on the left has a high compressor efficiency and the one on the right has a low compressor efficiency (note how i've changed the throttles and the different fuel flow).  Note how the temperatures on the right are all higher.  This a symptom of a less efficient component.  The engine has to work harder to generate the same thrust.  There are a number of other outputs.  You can also play around with other components, e.g. see how a degraded turbine efficiency looks versus a degraded compressor efficiency.

The only thing that this simulator does not have is rotor speed. For that, although I've not run out the calculations, I think that fan speed won't change too much with HPC efficiency, at least for a high bypass configuration.  Like I said, the control is going to change fuel flow to get back to the same thrust (via EPR), and since the majority of the thrust comes from the fan, the fan speed will be about the same.  The core speed, on the other hand, should go up.  Because the core has to work harder to produce the same amount of energy output.


How can I get started on a winglet design for a small remote controlled aircraft?

For best results, put good flaps on the wing and forget using a winglet.

If you insist on bending the wing up at its end, just continue with the tip airfoil and select the incidence such that your circulation distribution over the wing and winglet will become elliptical when you plot it in a straight line. The small size of your airplane implies that you will not need to unload the tips to reduce root bending moment.


Four Fundamental Forces

Weight

Weight is the force of gravity acting upon an object's mass.  The mass of an airplane is the sum of all parts that make up the airplane, including fuel and lubricating oils, crew/passengers, and cargo.  In a normal flight attitude, this force acts in the down direction, and it will always act towards the earth's center of gravity.

The airplane's center of gravity, or CG, is the location where the aircraft's mass/weight is evenly distributed in all directions.  Optimally, the CG should be as close as possible to the airplane's center of lift.

Lift

In a normal flight attitude, lift is the force opposing weight, acting in the up direction.  It is produced by the interaction of the wings and fuselage with the surrounding air as the aircraft travels through.

There are three scientific principles at work in the production of lift as it applies to aircraft.

Bernoulli's Principle: As air travels faster, its pressure decreases.  A typical airplane wing is designed like a foil, where the upper surface is comparatively rounder than the lower surface.  Air flows faster and at lower pressure over the top of the wing than air flowing underneath it, actually arriving somewhat earlier at the trailing edge than the air traveling underneath the wing.  This pressure difference accounts for most of the lift, but not all.
The Coandă Effect: Airflow is attracted to nearby surfaces.  Air "hugs" the wing as the wing passes through it.  Additionally, since the airflow over the wing is faster than that below the wing, the net result after the wing has passed through is downward air movement.  As the wing angle relative to the initial airflow (the angle of attack) increases, the trailing airflow is increasingly deflected downward.  (However, too much angle of attack will result in disrupted airflow on the leeward side of the wing, causing the wing to stall, resulting in a loss of lift.)
Newton's Third Law of Motion: A force in one direction caused by an object is countered by an equal force upon that object in the opposite direction.  Air deflected downward off the trailing edge of the wing results in a simultaneous upward force on the wing itself.

Drag

Drag is the force of all friction acting upon the airplane, operating in the backward direction.

Drag comes in many varieties.  Skin friction is the resistance caused by moving a solid object (the plane itself) through the air.  Induced drag occurs at the wingtips, where the high pressure air below the wing flows into the low pressure region above the wing, creating inwardly rotating swirls of air (vortices) behind the airplane.  Additional drag is encountered as an airplane's speed approaches the speed of sound and beyond.

Thrust

Thrust is the force causing the aircraft to move forward through the air.  In most airplanes, thrust is produced by a propeller or jet engine.  This is Newton's Third Law in effect as well: as air is pushed backward, the aircraft moves forward.  This forward motion creates a flow of air over the wing, producing lift.

When an airplane's thrust produced equals its drag, the airplane remains in level flight (barring any pilot control inputs).  When thrust exceeds the drag, the increased airflow over the wing creates additional lift.  When thrust is less than drag, the decreased airflow results in less lift being generated.


Is it ok to lift locked armrests on aisle or window seats?

I'll have a go at this, but this answer applies only to the US.

First, is it legal? As far as I can see, yes. There are various regulations (e.g. 14 CFR 121.317) about specific items that passengers have to be briefed on and comply with instructions on. They include smoking, seatbelts, emergency exits, screens and tables etc. But there's no explicit mention of armrests and I didn't see any generic clause like "any other equipment" or whatever. So in the absence of any explicit or general regulation that says you can't, I would say you can.

Second, will it get you "into trouble"? Maybe. As the answer to a related question shows, the FAA doesn't want armrests to become an obstacle to evacuation and they advise crew members to make sure that armrests are locked down for takeoff and landing. Many airlines I've traveled on have an announcement about the armrests, even if there's no regulation that requires it. If the crew ask you to put your armrest down and you refuse then the 'best' thing that can happen is that they decide you're rude but not dangerous and let it go. But if you refuse repeatedly and they decide you're being confrontational or unlikely to follow other instructions then 14 CFR 91.11 would apply:

  No person may assault, threaten, intimidate, or interfere with a
  crewmember in the performance of the crewmember's duties aboard an
  aircraft being operated.

Under that regulation, if the crew decides you're "interfering" with their duties (which include keeping you and everyone else safe), you'll probably get a police escort off the aircraft, especially if alcohol is involved.

But having said all that, I don't think this is a big deal at all. The FAA's concern seems to be about armrests that get stuck at an angle, not about ones that can be fully lifted. I've often seen passengers put up their armrests and I've never heard a crew member comment on it, but if they do ask you to lower them, arguing about regulations would probably be a bad idea.


When using the phonetic alphabet, for airways, should we say Uniform or Upper?

ICAO

ICAO Annex 11 and Doc 4444 confirm the usage of Upper.

Airways are four groups per ICAO, the older group is A, B, G, and R. Those stand for Amber, Blue, Green, and Red. There are three other groups.

So an airway named UG1 will be called Upper Green (not Golf) One on the radio.

Example they give in Doc 4444:

  N0450F310 L9 UL9 STU285036/M082F310 UL9 LIMRI

  (...) the flight will proceed on Airways
  Lima 9 and Upper Lima 9 to a point bearing 285 degrees magnetic and 36 NM from the Strumble VOR. From this (...)

Jeppesen Airway Manual also confirms it, check page 251:

FAA (for airways only)

Q is called Q (kyo͞o) on the radio (not Quebec), J is called J, not Juliet or Jet (Jet is what it means). See FAA JO 7110.65X 2−5−1 AIR TRAFFIC SERVICE (ATS) ROUTES.

  VOR/VORTAC/TACAN airways or jet routes.
  State the word “Victor” or the letter “J” followed by
  the number of the airway or route in group form.

  EXAMPLE−
  “Victor Twelve.”
  “J Five Thirty−Three.”

The FAA is similar in using the color code for the aforementioned group:

  Colored/L/MF airways. State the color of the
  airway followed by the number in group form.

  EXAMPLE−
  “Blue Eighty−One.”

Also check the FAA Instrument Procedures Handbook, page 2-24 of Chapter 2, here are two examples they give:

  UR5—Upper Romeo Five

  UW456—Upper Whiskey Four Fifty Six

Yes the FAA handbook does not agree with their ATC Job Order regarding R being Red (this will be for the old airway system such as those still in Alaska).

Note: the question asks about airways, the information here is not for tail numbers, navaids, etc., only airways.

See here for how the FAA decides on the designations: How are Victor airways defined and numbered?


Can Microsoft Flight Simulator help me learn to fly (or make me a better pilot)?

Clarification:This was written about Microsoft Flight Simulator X (FSX).   Parts of the answer probably apply to the new Microsoft Flight Simulator (2020 release), but that isn't what I had in mind when writing this.  Maybe a new answer will be appropriate after using MSFS for some time.

@Pondlife gave a very good answer, and I'll add a few bits to that.
Even after having gotten my license, I still use flight sims (mainly Microsoft FSX and X-Plane 10) for some practice.
Before flying into an unfamiliar airport, or over an unfamiliar area, I'll often load it up in a simulator, and fly it.
Especially when I was a student, I found this incredibly helpful for my long cross country flights. You can look at a map all you want, but its still not the same as sitting in the simulator, and looking around ("I see the mountain on my left.... and the lake below me.  I can follow this valley all the way to the airport..." etc). And I've generally found the simulator, with good terrain and textures loaded, can be pretty close to reality.
The night before I did a student flight from KBFI to KVUO, I flew the entire thing in FSX. The next day, it really felt pretty much like making the same flight all over again. Based on the landmarks, timing, views, etc, I knew exactly where I was, and I was confident that everything was going right.

That said, in my opinion there are some things simulators do very poorly.
Some of these are:

TakeoffsThe application of power and left-turning tendency on the ground just doesn't feel realistic at all. The climb out doesn't feel right.

LandingsGround effect is difficult to observe in a simulator. The flare doesn't feel like reality, and touching down (or bouncing) is not realistic at all.

Cross Control, Slip, Spin & Unusual AttitudesAnything beyond basic maneuvers up to 30 degrees bank or 20 degrees climb doesn't match reality.

This is dependent on your simulator, some perform certain things more realistically than others.
Because of these limitations, I would NOT use a flight simulator to try to learn takeoffs, landings, or certain maneuvers. (You can learn the "procedure" in a simulator... when to reduce power, when to add flaps. But the "feel" will be all wrong).

If you're going to try to incorporate flight sim into your training, there are some basic things you should do:

Spend LOTS of time configuring itUnlike a video-game, this is not "plug-n-play". Spend time learning all the controls.
Turn on RealismWhen adjusting your controls, set all "null-zones" to zero, set "Sensitivity" to maximum, turn off helpers like "auto-mixture" and "auto-rudder", etc. (However, I do keep "Gyro-Drift" turned off in my sim.  Its annoying, and adds little practical value)
Turn on WeatherThe flight simulators typically come pre-setup with zero wind, good weather, standard temperature, etc. Configure yours to pull from real-world weather sources, or add some clouds, a variety of winds, and don't always fly at noon. Set the timing for early morning flights, twilight flights, night flights, etc.

Another "fun" area where flight simulators can be slightly helpful is in emergency procedures.
Typically in real-world training, my instructor told me:  "We're going to practice engine-out emergencies" and my mind immediately starts preparing for that... And naturally, we have to do them at a safe altitude in a safe area.
In a flight simulator, you can set up the computer to give you a random emergency at a random time. You might get the problem on short-final, or over a metro-downtown area. Something that you just can't do in reality.
I haven't had any real-life emergencies, so I don't know how accurate a flight simulator is. But I believe that some practice is better than no practice at all, and flight sim lets me fly into storms, icing, get lost in fog, fly approaches below minimums, have an engine seize up on me, etc, all without risking my butt or a $200,000 airframe.

Since @Lnafziger suggested more specifically addressing flight training:
I do believe that flight sim can help with certain aspects of training, but in other areas, it is no help at all, or actually harmful.
Training Areas simulators can help with:

ProceduresReviewing steps and procedures before going in the air.  For example, for a student, steep turns or stall recovery can be a little nerve wracking at first. It may be much easier (and cheaper) to do it in a sim with an instructor, discussing all the steps and reasons for actions. Then when the student gets in the air, they won't have the "feel" for it, but at least the general process is already familiar.

NavigationTuning and identifying VORs, and interpreting the needles can be done just as well be done on the ground as in the air. If the sim has good, realistic terrain (I prefer MegaSceneryEarth), it can also be used for some visual reference lessons.

Instrument interpretationScanning and cross-checking the 6-pack of instruments can be done in a simulator just fine, and a student can practice doing it for long periods of time for a fraction of the cost of flight time.

Training Areas simulators are very bad at:

On the ground & Outside the planeAnything on the ground, such as taxiing and parking, or anything outside the airplane, such as pre-flight inspection, or weather interpretation, just doesn't work in a sim.

RadiosI haven't seen any flight sims that really work for the practice of talking on or listening to the radios. (I haven't used VATSIM, which might help). I don't think there's any good substitute for actually flying in a real airspace while simultaneously engaging in real radio conversations.

FeelEven the best full-motion sim isn't a substitute for the forces a student feels in a real airplane. This is especially true on ground-reference maneuvers, takeoffs, and landings, where I feel sims fall far short of reality.  No one will ever get a "feel" for the plane from a simulator.

For much more information on the topic, I recommend these books:
Scenario-Based Training with X-Plane and Microsoft Flight Simulator

Microsoft Flight Simulator X For Pilots Real World Training

And here's a picture of my old simulator rig.
(Its been improved a bit since this picture)


How will flying through mountains cause altimeter problems?

You basically answered the question yourself already.
Venturi states: the sum of pressures in a system stays constant.
The system is the valley and the pressures are the air (static pressure) within the valley and the wind flowing through it (dynamic pressure).

Static Pressure + Dynamic Pressure = Total Pressure
If the wind flows faster, we got higher dynamic pressure. Since the sum stays constant the static pressure has to fall as a consequence.
Of course, then, all pressure levels shrink under lower static air pressure as they would do under cold temperatures. Flying at a constant pressure level results in following these shrinking levels and eventually end up at a lower true altitude.
That's the main reason why your true altitude is lower than your indicated.

If you knew the actual static pressure in the valley, you could adapt your altitude by the rule of thumb: per 1hPa: 30ft

So answering your question: if the venturi effect reduces static air pressure in the valley, the above stated applies.


What would be the drawbacks of using a rotating engine as thrust reverser on airliners?

I wouldn't worry to much about the mass of the engine. That's actually not the biggest problem. Instead, I'd be scared far more by the angular momentum. That turbine has a large moment of inertia and also a higher angular velocity.To flip it, you have to reverse the angular velocity. It's essentially flipping a gyroscope, but this is a gyroscope weighing several tons.


Are 'climb via a SID' instructions actually used in the US?

In my experience, I've received a climb via SID many times at airports like Las Vegas and Teterboro.

This is common at certain airports, but a lot of airports don't use it because the procedures aren't designed that way.

I think that a lot of pilots, especially those flying smaller non-turbine powered aircraft, don't receive this type of clearance because:

They are flying at smaller airports that don't have a SID which uses it, or
They are not assigned the SID's which do have it because the SID is only assigned to turbine-powered aircraft or aircraft capable of flight above a certain speed or altitude.

It is also a relatively new procedure in the US.  They were originally going to start using it in 2014, but it got delayed and was finally implemented a year or two ago (I don't remember exactly when).  For a while, the US was only using "descend via" clearances, and not "climb via" clearances.

Here are a couple of resources about this:

NBAA PBN site
FAA Climb Via/Descend Via Speed Clearances
Frequently Asked Questions
FAA “Climb Via” and “Descend Via” Procedures and Phraseology Air Traffic Policy Notice


Do the stabilators on the F/A-18 also have a roll function similar to the F-22?

Yes it has differential stabilators. Below is a description from the F/A-18's (A/B/C/D) NATOPS flight manual. Almost every surface including the flaps and leading edge devices are used in rolling the aircraft (fly-by-wire magic):

2.8.2.8 Control Augmentation System (CAS).
The lateral control system uses ailerons, differential trailing edge flaps, differential leading edge flaps, differential stabilator, and rudders to achieve the desired roll characteristics. Scheduled air data roll rate feedback is used to augment inherent airframe roll damping. At high airspeeds, aileron travel versus stick movement is reduced and the ailerons do not deflect above 600 knots. Differential stabilator and differential trailing edge flap travel is reduced at high speed to prevent exceeding structural limits. The leading edge flaps deflect differentially up to ±3° when below 30,000 feet and above Mach 0.7. Differential flaps are not used in the takeoff or land modes nor above 10° AOA in the auto flaps up mode. At low airspeeds, aileron and differential stabilator travel are reduced with increasing AOA to minimize adverse yaw. Differential stabilator may also be limited due to a pitch command which has priority. With lateral stick deflection, the rolling-surface-to-rudder interconnect (RSRI) schedules increasing rudder deflection as a function of decreasing airspeed and increasing AOA for roll control, coordination, and to reduce adverse yaw.


How is the weight of an airplane measured?

The empty weight of airplanes can only be given to single-pound precision for one specific airplane. Minute differences in metal sheet thickness, equipment and paint will make sure that there is a difference of many pounds between airplanes of the same type and furnishing. Add to this the difference in seating, galleys and instrumentation between airplanes of the same type which are operated by different airlines, and a precise number as in your question becomes almost meaningless. A better way would be to give a range in which most airplanes will fall, or to round the number like the Concorde weight of your question.

Weighing is quite straightforward: All tires of the landing gear are placed on scales and the weights are summed up. If the attitude of the airplane does not change, the weight on the tires can even be measured consecutively, so only one scale is needed. Small floatplanes can be suspended from a crane with a scale in the line holding the aircraft.

In Ernst Heinkel's biography he remembers an aircraft deal with the Soviet Union in the late 1920s. He had to deliver five floatplanes of a specified weight, and the Russian approval inspectors insisted on all planes having the exact same weight. Of course the planes were not identically heavy, but his advantage was that the scale in his factory was indicating the weight by printing it on cards. So the evening before the inspectors came, he let one aircraft be weighed five times, put the cards back into the machine and had the printing mechanism disabled. The next day he closed the business successfully with his very happy Russian guests.


Who is responsible to check for radar-altimeter disagreement?

That depends on regulations but broadly speaking it is ultimately always the Pilot In Commands responsibility to make sure all instruments are functioning properly.

  § 91.3 Responsibility and authority of the pilot in command.

  (a) The
  pilot in command of an aircraft is directly responsible for, and is
  the final authority as to, the operation of that aircraft.

Now your probobly thinking "But if the autopilot is flying then who's really in command" well its the opinion of the FAA that even if the autopilot is taking care of everything you are still responsible for the aircraft and for making sure everything is working correctly. This question covers that more in depth.

As for things like warnings, alerts and auto-disconnects that depends on the specific system in question and the desired failure mode. For example if you have 3 radar altimeter inputs to an autopilot/auto-throttle the system can reasonably detect if one is erroneous and use the other two. There is lots out there on triple redundancy which is the basis of this.

What if the aircraft starts barking alarms at you saying "TOO LOW!, GEAR!" how can you even check that aside from cross checking your altimeters?

You can check your GPS altitude if available, while not a legal source for navigation you bet its a good backup.
If you are flying a stabilized approach (and in a plane like that you really should be) you should, at any given time know generally where you are on the approach and if you are on the glide slope (when available) you can gain a pretty good idea of your altitude.
In VMC, just look out the window!


What flight simulator software did Captain Zaharie Ahmad Shah use?

Based on the red little strip (notification bar) on the bottom of the instrument panel in the middle, it must be either Microsoft Flight Simulator or Lockheed Martin Prepar3d. The red notifiation bar is specific to Flight Simulator 2004 (FS9) and Flight Simulator X (FSX). Laminar Research's X-Plane uses a different graphics engine and would not have produced a scenery that looks like on the three outside view screens.

The source is not really quotable, but if the name and picture can be taken a proof, then Mr Shah himself writes on the X-Sim.de Forum about FS9 and FSX being used:

  Elo guys,
  zaharie here.... pls to join x-sim. About a month ago I finish assembly of FSX and FS9 with
  6 monitors .... with the latest graphic card ( 2 pieces of asus 7970) on one cpu awesome view on 3 panasonic 32 in. LCD HDMI
  and 3 touchscreen Dell 21 inches for main (MCP) , center pedestal, overhead panel.
  time to take to the next level of simulation.Motion! looking for buddies to share this passion.
  Capt Zaharie Ahmad Shah
  BOEING 777 MALAYSIA AIRLINES

Answer based on own experience with all 3 simulators/publishers.


How can the pilot tell the center engine failed on a piston aircraft with three engines?

If the engine quits you will lose some thrust which will affect the plane's handling. You may even begin to descend slowly which the pilot will notice.

Most importantly you have engine instruments which will tell you, quite quickly, the engine has quit. If you have one, your manifold pressure will drop since you are no longer producing power, or your tach will reflect what is happening.

If all that fails you I would think there would be an audible difference if the engine cut out.

This is the cockpit of the aircraft in question:

(Image Source: Jetphotos.net)

It does show independent MAP and RPM gauges for each engine as opposed to some planes that have a single gauge with multiple hands (one for each engine). You would surely be able to see an altered reading on one of these gauges.


Why would a plane drop 14.000 ft mid flight?

I looked up the flight on Flightradar24.com. The descent starts at 16:10 UTC and ends at 16:29 UTC, going from 38.000 feet to 24.000 feet. So, the aircraft descended 14.000 feet in 19 minutes.

14.000 divided by 19 makes roughly 750 feet per minute, which is a relatively normal descent rate for airliners.

The cause for this is probably an ATC instruction. The descent starts around 20 minutes ahead of the border of the U.S.A and ends directly in front of it (SSM VOR is the entry point to US Airspace).

Source

So, this is probably the cause for the descent: The pilots contacted the US controller around 20 minutes ahead of them entering US airspace. The controller then instructed the pilots to descent to 24.000 feet and reach this altitude at the SSM VOR. So, no uncontrolled drop there.


Can the four-engined Lockheed JetStar II fly on one engine?

I have 3000 hours in jetstar.... The answer is no... It will not fly on one... Two yes and you really don't need that much rudder.. In the simulator with two out I used to put the inboard operating engine at 98% and modulate the outboard engine to control speed/sink doing that it really only needed 1/4 rudder trim


How does one choose the number of blades and the diameter required for a turboprop propeller?

The prop diameter is chosen to provide suitable ground clearance for the desired installation. Then the reduction gearbox ratio is chosen to keep the prop tips subsonic. Then the number of prop blades is chosen to absorb full engine power. Compromises then get made to take advantage of off-the-shelf props in the market and standard gear ratios offered by the engine manufacturer.


Can the safety of the Boeing 777 be extended to other models?

What's the "safest aircraft" depends in large part on who operates it, how they operate it, and where.

For many operators the 777 will be their prestige airliner, being assigned the most senior, most experienced, crews, the best maintenance, etc. etc..

That alone will mean less incidents and accidents than other types. They also have the range and ceiling to be able to fly around or over most serious weather. A 30 minute detour on a 10 hour trip can be made up, a 30 minute detour on a 1 hour trip in a 737 or A320 can't be (even if the aircraft would have the spare fuel to fly that detour).

The rest is mostly statistics. I seriously doubt there have been statistically more accidents per hour flown or per rotation on say an A340 as compared to a 777. There have been more airframe losses, but those include several lost on the ground due to them being stuck on airports in warzones (think what happened on Sri Lanka where Tamil separatist mortar bombs destroyed several airliners on the ground, damaging the until then flawless safety record of the type).

There have been AFAIK 3 777 hull losses (including the missing MH370) in flight.

Given the far higher number of say 737s in operation, and the far longer service history of that type, often with operators with shady operational procedures (more than a few are for example blacklisted by the EU) it's little surprise there have been more hull losses among the type. But comparing say the 737-900 only with the 777, with somewhat similar technology and number in service, as well as similar prestige level for crew assignments, you'll find a similar safety record.


Is there a comprehensive source for aircraft specification data for most of the aircraft in the world?

You can find a lot of information about aircraft in their Type Certificate Data Sheet that is available from the FAA or other certificating authorities. The FAA's is located here. It takes a bit of time to find certain things, and other things aren't included like range, or sometimes dimensions.


In xflr5,how is the value of Fz calculated?

When you have taken the Cl of the airfoil concerned, the Co-efficient refers to an infinite wing. You have to compute the CL of the wing, which refers to a finite wing, taking into consideration the 3D nature of the flow.


These "FICON" NOTAM's contractions aren't in the FAA contraction list. What do they mean?

FICON is outlined in FAA JO 7930.107 "FICON REPORTING".

FICON is the "FIeld CONditions reporting. It identifies information that used to be called "braking action", but is now a little more succinct.

The conditions for the runway are reported in thirds, [First Third]/[Middle Third]/[Last Third], with the following data outlined on page 6:

So 5/5/5 means that the runway is covered with frost or is wet and is "damp or 1/8" or less of standing water". Pilots used to report this as "good" braking action.


Where is the center of gravity on a tiltrotor?

The c.g. limits change in forward and hover flight, so loading the aircraft takes special care. On the Bell XV-15, the range of c.g. was around 16 inches. For comparison, the internal cabin was 157 inches long. Based on the fuselage stations below and the image above, the c.g. limits were very close to the rotors in helicopter configuration.
For the control method in-flight, see: How do VTOL aircraft like the V-22 Osprey not tilt?
Commentary: how much forward ballast (see image below) an aircraft like the V-22 has -- I don't know (classified).

Maisel, Martin, D. C. Borgman, and D. D. Few. "Tilt rotor research aircraft familiarization document." NASA TN X-62 407 (1975).


What do these ramp markings mean at KIFP?

They are helicopter parking markers, as per the AC that defines them:

I was never taught about this in my training and it was not on the fixed wing PPL exam nor is it on the FAA's quick reference guide but its a good idea to know what they are.

Although interestingly they are not where the airport diagram denotes the "Helicopter Parking"


Why do the wing tips on the Boeing 777X fold up instead of down?

The FAA has decided/proposed (Nov 2017) that the folding mechanism must comply with certain standards, of which:

The wingtips must have means to safeguard against unlocking from the extended, flight-deployed position in flight, as a result of failures, including the failure of any single structural element.
All sources of airplane power that could initiate unlocking of the wingtips must be automatically isolated from the wingtip-fold operating system (including the latching and locking system) prior to flight, and it must not be possible to restore power to the system during flight.
The wingtip latching and locking mechanisms must be designed so that, under all airplane flight-load conditions, no force or torque can unlatch or unlock the mechanisms. The latching system must include a means to secure the latches in the latched position, independent of the locking system.
It must not be possible to position the lock in the locked position if the latches and the latching mechanisms are not in the latched position, and it must not be possible to unlatch the latches with the locks in the locked position.

Source: federalregister.gov (broke it down into paragraphs for easy reading)
As to why they chose up and not down, only the responsible engineering team at Boeing can answer that. My guess is that they trust their design over the drivers around the plane when it's parked.
This is echoed by airinsight.com:

(...) Boeing could point out that the upward folding wing offers considerably less opportunity for "ramp rash".  It is, unfortunately, true that vehicle drivers around aircraft are often clumsy and hit aircraft.

Interestingly, the folding wingtip was envisioned 28 years ago for the 767-X (what eventually became the 777):

(flightglobal.com)