Is it legal to use GPS to navigate VOR Airways?

It's legal if you have a suitable and acceptable RNAV system as described by FAA Rules.
Also realize that it is only RNAV capability that provides for 'direct routing' without recourse to DR - Dead Reckoning - or Radar assisted DR needed by traditional Radio Aid based navigation.
When an RNAV system navigates to an out of service VOR, it is flying a computed course from it's position vis a vis the VOR to the VOR position. This is no different from flying from any point 'A' to any point 'B'. That is the whole purpose of the Advisory Circular being quoted. A few more extracts from the AC (quoted below) should make it amply clear.

FAA AC 90-108 extracts . . .

PURPOSE. This advisory circular (AC) is intended for the following purposes:

a. Provides operational and airworthiness guidance regarding the suitability and use of Area Navigation (RNAV) systems while operating on, or transitioning to, conventional, i.e., non-RNAV, routes and procedures within the U.S. National Airspace System (NAS). This guidance material applies to two broad categories:

(1) Use of a suitable RNAV system as a Substitute Means of Navigation when a very high frequency (VHF) omni-directional range (VOR), distance measuring equipment (DME), Tactical Air Navigation (TACAN), VOR/TACAN (VORTAC), VOR/DME, non-directional radio beacon (NDB), or compass locator facility including Locator Outer Marker (LOM) and Locator Middle Marker (LMM) is out-of-service, i.e., the Navigation Aid (NAVAID) information is not available; an aircraft is not equipped with an automatic direction finder (ADF) or DME; or the installed ADF or DME on an aircraft is not operational. For example, if equipped with a suitable RNAV system, a pilot may hold over an out-of-service NDB.

(2) Use of a suitable RNAV system as an Alternate Means of Navigation when a VOR, DME, VORTAC, VOR/DME, TACAN, NDB, or compass locator facility including LOM and LMM is operational, and the respective aircraft is equipped with operational navigation equipment that is compatible with conventional NAVAIDs. For example, if equipped with a suitable RNAV system, a pilot may fly a procedure or route based on operational VOR using that RNAV system without monitoring the VOR.

b. Qualified RNAV Systems. Describes the types of RNAV systems that qualify as “suitable RNAV systems”

DEFINITIONS. For the purposes of this AC, the following definitions are provided:

b. Area Navigation (RNAV). A method of navigation which permits aircraft operation on any desired flightpath within the coverage of ground- or space-based navigation aids or within the limits of the capability of self-contained aids, or a combination of these.

g. Substitute Means of Navigation. The use of information from an RNAV system in lieu of that from out-of-service conventional NAVAIDs and/or inoperative or not-installed navigation equipment compatible with conventional NAVAIDs.


What are the ground and flight requirements for high performance endorsement?

You seem to be confusing a high-performance endorsement with a high-altitude one. Both are in 14 CFR 61.31. They're too long to quote here in full, but the high-performance one comes down to this:

  (i) Received and logged ground and flight training from an authorized
  instructor in a high-performance airplane, or in a flight simulator or
  flight training device that is representative of a high-performance
  airplane, and has been found proficient in the operation and systems
  of the airplane; and

The high-altitude one is where your 25,000' number comes from:

  (g) Additional training required for operating pressurized aircraft
  capable of operating at high altitudes. (1) Except as provided in
  paragraph (g)(3) of this section, no person may act as pilot in
  command of a pressurized aircraft (an aircraft that has a service
  ceiling or maximum operating altitude, whichever is lower, above
  25,000 feet MSL), unless that person has received and logged ground
  training from an authorized instructor and obtained an endorsement in
  the person's logbook or training record from an authorized instructor
  who certifies the person has satisfactorily accomplished the ground
  training. The ground training must include at least the following
  subjects: [...]

As well as the ground training, you have to do (at least) the following in an aircraft or approved simulator:

  (i) Normal cruise flight operations while operating above 25,000 feet
  MSL;

  (ii) Proper emergency procedures for simulated rapid decompression
  without actually depressurizing the aircraft; and

  (iii) Emergency descent procedures.


Calculations for altimeter settings for variations in barometric pressure

Question 1: 550 ft.

Question 2: 660 ft.

(rounded to the next multiple of 10).

Atmospheric pressure drops by 1 mbar for every 8.5 m or 27.7 ft of altitude between 0 and 1000 ft, and the differences of your cases from the standard atmosphere are small, so I did not use corrections.


How to calculate "duty" when between flights in a 135 operation

I have not checked the latest regs, but the time beginning at the point where the pilot is done with all postflight duties until the time the preflight duties begin (ex. checking weather) is considered rest time ONLY IF the pilot is really off the clock.  If the company requires anything of the pilot (ex. "stay near the plane...just in case"), it is not rest time.


Why is one of two parallel runways sometimes closed in foggy weather?

SFO makes use of simultaneous close parallel approach operations.  This allows higher density operations than would otherwise be possible for runways spaced so close, but to make use of these ops, in SFOs case, requires 1600 ft ceilings and 4 sm visibility due to the requirement that aircraft maintain visual contact during close parallel operations.

It does look like SFO can run the ILS approaches simultaneously outside of close parallel operations, but is possible the required spacing makes its pointless to use both runways.  If weather was bad enough that cat II ops were in effect, I don't see any verbiage on the cat II charts indicating simultaneous ops are approved.

Regardless of how precise your instruments are, there are strict requirements on how close you can be to another airplane in the approach phase and that separation be maintained if both parallel aircraft perform the missed approach.

The ability to run parallel approaches in low visibility depends on how far apart the runways are laterally.  Airports like IAH and ATL can run triple parallel ops and if you take a look at their runway layout you will find they are spaced quite far apart and may be displaced relative to one another.


What are the implications of a Memorandum of Understanding during an aircraft order process?

A Memorandum of Understanding (MOU) isn't an aviation term or practice, it's a general business/legal term for a 'pre-contract' of some kind. Before two companies commit to a legally binding and perhaps very expensive contract, they'll often prepare an MOU to make sure that everyone involved has the same understanding of what will be in the contract. That way, there shouldn't be any big surprises or fundamental disagreements when the real contract is prepared.

In the context of aviation, that could be things like how many aircraft will be purchased and when, or what the price is anticipated to be, or anything else that both side consider important. That means that the information in an MOU could be very interesting for other parties ("can you explain why our competitors are paying you $50m less per aircraft than we do?"), so they're usually confidential.

Another common use for MOUs is for PR/Marketing purposes. If two companies are discussing a joint business venture they might come up with an MOU and use it to generate market interest or even raise capital ("I know we're a small company but we have an MOU with Boeing to jointly research alternative fuels").

Given that background, I don't think it's likely that you'll get any specific answers to your questions. An MOU could include all the things you mentioned but only a real contract is enforceable.


How come nobody survived Air Moorea 1121, yet other people have survived crashes from altitudes more than 90x higher?

I'm guessing you consider your examples to be crashes from "90x higher" because the initiating events happened at high altitude. This extra altitude was actually a good thing in these cases, because while the pilots lost most control of the aircraft, they were still left with partial control. The extra altitude gave them plenty of room to figure out what was wrong with the airplane and how to control it with what was still working. This allowed them to end up in more of a crash landing rather than just a crash. In airliners that really do crash from higher altitudes, there are no survivors.

United 232 was more of a crash landing. Although the hydraulic systems were lost, the plane was still trimmed for level flight and the pilots could use the remaining engines to control the plane. They had plenty of altitude and airspeed at the time of the engine failure to get the plane under control and figure this out. This resulted in the crash landing where about 2/3 of the people on board survived.

Japan Air 123 was similar in that the aircraft lost hydraulics but they also lost most of the vertical stabilizer. Again, this happened at a higher altitude which gave the pilots room to react to the issue. The pilots still managed to fly the plane for a while but ended up crashing into the mountains. The survival rate was less than 1% though this was partially due to delay in the rescue operation.

Air Moorea Flight 1121 lost its elevator control cable. While the pilot could have used trim to control the aircraft's pitch, the airplane initially entered a dive and 400 feet was much too low to recover from this. If the cable had broken at a much higher altitude it's possible the pilot could have regained control.

Another point to remember is that in a large airliner like the DC-10, the passengers have a lot around them to cushion the impact. In a small plane like the DHC-6 this isn't the case. A crash into the water also results in a much higher impact, and any survivors would have to be able to swim free to the surface.


Why doesn't the centre of pressure move in the case of a symmetric aerofoil?

Simple answer:
The pressure difference between lower and upper side on an uncambered airfoil or a flat plate can be summed up in a force acting at the quarter point, independent of angle of attack. Only when separation starts will this pressure distribution change shape and the force will move backwards. Since a flat plate has a sharp leading edge, separation happens at much lower angles than on an airfoil. If you think this is tautological, please read on.
More precise answer:
In potential flow theory, circulation strength is proportional to the local pressure difference on both sides of a body. When I now talk about circulation, just think pressure difference.
The distribution of the circulation strength $\gamma$ over an uncambered airfoil is given by Birnbaum¹ as $$\gamma = \sqrt{\frac{1-x}{1+x}}$$ for the lengthwise coordinate $x$ running from -1 at the leading edge to +1 at the trailing edge of the airfoil. Like this:

Now it is important to note that the shape of this distribution stays the same, regardless of angle of attack. Only the intensity of the circulation varies with angle of attack. Until separation starts, that is.
If you calculate the centroid (= center of gravity of the area under this curve), it lies at -0.5. If we now translate the X coordinate to the more usual 0 at the leading and 1 at the trailing edge, this center of gravity sits at 0.25 or the quarter chord point. And it stays there, regardless of angle of attack (again, until separation starts!). Circulation is equivalent to lift, so the same holds true for the pressure coefficient over chord.
This explains why the pressure distribution of a symmetric airfoil stays at the quarter point. It does so, too, in case of the flat plate, only that the angle of attack range where this is valid is much narrower. The sharp corner at the leading edge of the flat plate will cause air to separate already at small angles of attack, so the validity of potential flow theory (of which this proof is part of) is limited in case of a flat plate. Once separation starts, the pressure over chord tends to stay constant, so the center of gravity of the pressure distribution shifts towards X = 0.5.
¹ W. Birnbaum: Die tragende Wirbelfläche als Hilfsmittel zur Behandlung des ebenen Problems der Tragflügeltheorie. Zeitschrift für angewandte Mathematik und Mechanik 3, pages 290-297 (1923)
https://doi.org/10.1002/zamm.19230030408


What is the proper air strip closure procedure with the FAA?

It looks to me like you need to file FAA Form 7480-1, Notice of Landing Area Proposal.  There is a checkbox for "Deactivation or Abandonment".

The form explains that you have to give 90 days advance notice.  So you shouldn't make any changes until 90 days after filing the form.  This presumably gives them time to update charts, so that pilots know the airstrip is no longer usable.

The form has the address and phone number for your FAA regional office, who might be able to help if you have questions about how to complete the form.


How does the safety record of the twin piston Diamond DA-42 compare to the single piston DA-40?

So it appears that Diamond answered this question for me.

See this page:
http://www.diamondaircraft.com/about-diamond/safety-features/

From this chart, it would appear that the DA42 has a slightly higher accident rate, and of those accidents, even more are fatal (which makes sense due to the higher speeds). Still loads safer that the SR22 though, and I'd personally prefer the 42 over water as well.


What is the floor of the class E airspace near KRHV when the tower is closed?

Short answer:

When looking at the airspace depiction on the sectional chart, it is logical to assume that the linear portion of the edge of the transition area with 700' floor, shown by the shaded magenta boundary, continues on through the blue segmented circle around KRHV, and this controls the floor of the Class E airspace in that area when the tower is closed and the Class D airspace reverts to Class G.  In that case, the Class E floor in area "1" is 1200' AGL and the Class E floor in area "2" is 700' AGL.  Similarly, it is logical to assume that the arcing circular edge of the 700'-floor transition area located north of KRHV also continues into the blue segmented circle around KRHV, but this section just barely extends into the blue segmented circle before it is intercepted by the linear edge of the 700'-floor transition area coming up from the southeast.

Long answer:

(Click here for a larger view of sectional chart centered on area of interest)

The ultimate authority for the answer to your question is found in the FAA's "Airspace Designations and Reporting Points" document, current edition Order JO 7400.11D.  The class D airspace for KRHV is described on page D-156 under the heading "AWP CA D San Jose Reid-Hillview Airport, CA".  No corresponding E2 airspace is listed-- it would be on page E-134 if it were present.  This confirms what we read in the Chart Supplement-- that the Class D airspace for KRHV reverts to Class G, not Class-E-to-surface, when the tower is closed.  The only exception is the small slice of airspace centered around the "6:30" position of the segmented blue circle around KRHV which does revert to Class-E-to-Surface when the Class D is inactive-- because it is part of an E3 "extension" associated with San Jose International (page E-153).

The magenta shaded border projecting southeast from the word "Evergreen" on the chart is the eastern edge of a "transition area" whose floor is 700' AGL, and your question is essentially asking whether this edge extends on into the segmented blue circle around KRHV, or deviates to include the entire segmented blue circle, or deviates in some other way.  Transition areas are "E5" airspace, and are described starting on page E-220 in the "Airspace Designations and Reporting Points" document.  The specific transition area we are interested in is described on pages E-960 through E-961, under the heading "AWP CA E5 San Jose, CA, San Jose International Airport, CA".  When reading this text, it is helpful to know that "San Martin Airport" (KE16) was formerly known as "South County Airport of Santa Clara County".

Here is the complete text of the E5 airspace description, with the relevant portion highlighted:

  That airspace extending upward from 700 feet above the surface within a 5-mile radius of the San Jose International Airport and within 4.3 miles each side of the NAS Moffett Field TACAN 157° radial extending from the NAS Moffett Field TACAN to 20 miles southeast of the TACAN and within 4 miles each side of the 139° bearing from the San Jose NDB, extending from the 5-mile radius of the San Jose International Airport to 24.3 miles southeast of the NDB and within a 6.9-mile radius of the South County Airport of Santa Clara County and that airspace bounded by a line beginning at lat. 37°30'00"N, long. 121°52'04"W; to lat. 37°22'00"N, long. 122°08'04"W; to lat. 37°22'00"N, long.122°24'04"W ; to lat. 37°30'00"N, long. 122°27'04"W, thence to the point of beginning. That airspace extending upward from 1,200 feet above the surface bounded on the north by lat. 37°30'00"N, on the east and northeast by long. 121°50'04"W; and the southwest edge of V-107, on the southeast and south by the northwest edge of V-111, and lat. 37°00'00"N, and on the west by the east edge of V-27 to lat. 37°30'00"N.

The 8-mile-wide strip of 700'-floor E5 airspace that extends 24 miles to the southeast of the San Jose NDB comes all the way up to the 5-mile-radius arc around San Jose International, and does not deviate either to avoid, or to completely include, the airspace enclosed by blue segmented circle around KRHV.  Likewise the curving edge of the 5-mile-radius-circle of 700'-floor E5 airspace around San Jose International continues a short ways into the blue segmented circle around KRHV, before it meets the linear edge of the 700'-floor E5 airspace coming up from the southeast.  So the edge of the 700'-floor E5 "transition area" does indeed run through the blue segmented circle around KRHV much as was sketched in the question.  Area "1" is outside the 700'-floor E5 transition area and has a Class E floor at 1200' AGL when the Class D airspace is inactive, while area "2" is inside the 700'-floor E5 transition area and has a Class E floor at 700' AGL when the Class D airspace is inactive.

This answer has followed the common practice of referring to E5 airspace with a 700' Class E floor as a "transition area".  This appears not to be actually supported by any current FAR or FAA document, including the "Airspace Designations and Reporting Points" document.  "Transition area" is a term from before the 1993 "alphabet" airspace re-organization, and actually included areas that had controlled airspace floors at 1200' AGL as well as at 700' AGL.  It is an obsolete term now, but still is often used by pilots, most commonly to refer to areas that have Class E floors at 700' AGL.  At any rate, note that area "1" is actually still inside the airspace that is defined as part of the E5 airspace associated with San Jose International-- specifically, it is inside the portion of the E5 airspace associated with San Jose International that has a 1200' AGL floor.  This answer does not intend to imply that there is some definitive reason to say that area "2" is inside a "transition area" while area "1" is not inside any "transition area".  The main point of this answer is simply that when the Class D airspace around KRHV is inactive, area "2" has a 700' AGL Class E floor while area "1" has a 1200' AGL Class E floor.

Note that the "Airspace Designations and Reporting Points" document uses nautical miles and true bearings.  A bearing of 139 degrees true is approximately 126 degrees magnetic at this location.


What are the differences between ADS + INS and ADIRS / ADIRU?

The primary difference is packaging, which saves space and weight. The ARINC 704A IRU is a 4 MCU size LRU. Likewise, the ARINC 706 ADC is also a 4 MCU unit. The ARINC 738A ADIRS combines both functions into a single 4 MCU LRU. Though the ADIRS also includes remotely mounted Air Data Modules (ADM) which reduce the amount of pitot/static plumbing.

Functionally, the ADIRS performs the same functions as the separate IRS and ADS. A big drawback to the older ADS was the need to run the pitot and static lines all the way to the LRU. These lines are a maintenance headache, requiring multiple connections all of which have the potential to leak.

The ADMs can be mounted near the pitot and static sources significantly reducing the plumbing. The ADM converts the pressures to digital signals passed to the ADIRU via ARINC 429 or similar data bus. This simplifies installation, maintenance, and weighs less.

It should be noted that newer aircraft are moving to even newer architectures. The Boeing 787 dispensed with ADIRS and went with the Goodrich SmartProbes for air data and an Earth Reference System (ERS) to replace the IRU.

The Goodrich SmartProbes do away with pitot/static plumbing entirely by incorporating the pressure conversion in the probe base. They also electrically cross-connect the probes to perform the ADC function with no separate LRU.

The ERS addresses the FAA/EASA concerns over common mode faults in the IRU by using an IRU/AHRS mixed sensor architecture. In each of the two ERS, the IRU acts as the primary reference with the AHRS acting as a monitor. The key is that the IRU and AHRS use different hardware and software so that a common design flaw can't affect both and cause an undetected failure.

It's just evolution in the function of the aircraft sensors. They do what they need to do. The big demand from Boeing, Airbus, et al, is to reduce size, weight, power consumption, and cost.


What is the difference between Full Throttle Height and Critical Altitude?

Bob Tait explains it perfectly:

Every turbo charged engine has a rated boost which is the maximum manifold pressure permitted for that engine. It is marked as a red line on the manifold pressure gauge. Because the ambient density drops with altitude, there will always be an altitude beyond which it will be impossible to obtain the rated boost. That is called critical altitude.
However the aircraft is still capable of climbing beyond that altitude but the manifold pressure available at full throttle will be less than rated boost. For every value of manifold pressure there will be some other altitude beyond which that particular manifold pressure will no longer be available. So every value of manifold pressure has its own full throttle height. Critical altitude is simply full throttle height for rated boost i.e. the red line on the manifold pressure gauge. (bobtait.com.au)


What about hours flown solo without a student pilot certificate?

Do I have to re-do the whole solo requirements or they will still count towards my hours?

You will probably not have to re-do the hours. An FAA examiner will look at your log, test you and decide whether to give you a license. It is unlikely that they would notice that your solo time was done before the student license was issued and then disallow the hours. If they did notice and disallowed the hours, you could appeal that decision.

As long as a CFI certified you for solo flight, the hours you did should count.

Do I need to file a complaint through AOPA or FAA or contact my AOPA representative?

No.

What are the rules and who is responsible for that?

It's your job as a pilot to know the regulations and follow them, including requirements such as obtaining student licenses and medicals. The CFI is not your nanny. It is YOUR responsibility to know the rules and follow them.


Is there a roadmap to satellite / inertial only based navigation?

I'm not aware of any program at present that does away with ground based infrastructure completely. Present plans are to have the ground based stations as a backup in case of a GNSS outage/interference.

The present FAA plan, for example includes DME while reducing the VOR coverage:

Navigation- En Route Transition; from FAA navigation Programs Update Sep 2013

As far as ground based navigational aids are concerned, the plan is to reduce the VOR coverage with VOR Minimum Operational Network (MON) as a middle step. However, the plan appears to be to retain DME at the expense of other Ground Based Navigation Systems (GBNS).

FAA's Alternative Positioning, Navigation, and Timing (APNT) project is geared up towards maintaining aviation operations in case of a GNSS outage. According to FAA:

  The Alternative Positioning, Navigation, and Timing (APNT) project is investigating alternatives for providing higher precision back-up for Global Positioning System (GPS)-based position, navigation, and timing (PNT) services.

However, Ground Based Systems are still a part of the program (though VOR is not) and serve as a backup for the GNSS. One of the options is to modify the existing DME facilities in order to improve coverage/accuracy.

International Civil Aviation Organization (ICAO) 2013-2028 Global Air Navigation Plan also stresses the importance of having some 'conventional' ground based systems as a back-up for GNSS:

  Conventional navigation aids (VOR, DME, NDB, ILS) are in widespread use globally, and most aircraft are equipped with the relevant avionics. The vulnerability of GNSS signals to interference has led to the conclusion that here is a need to retain some conventional aids or alternative navigation service solution as a back-up to GNSS.

ICAO also concurs that DME is the most appropriate ground based equipment to be used in the future navigation system:

  The implementation of PBN will make area navigation operations the norm. DME is the most appropriate conventional aid to support area navigation operations(i.e. assuming DME multilateration on board capability),since it is currently used in multi-sensor avionics for this purpose.

At present, as far as I'm aware, there is no available roadmap for satellite/inertial only based navigation systems as far as civil air transport is concerned. Though GNSS will remain the primary means of navigation for the foreseeable future, plans still retain ground based systems as a backup.


EASA part 66 licence conversion to the Japanese version?

You'll probably need a letter from your part 66 licence holder's authority.
I know people who get equivalent between French and Australian.
The best approach is to contact the Japan's competent authority (JCAB-MLIT) for the application details.
Regards


No alternate destination when flying from Oakland to Honolulu: is that correct?

There are plenty of alternative airports in Hawaii, but none in-between of course. So what the author is getting at is that you're probably going to be dead if you run into trouble.

While I can't say I know anything much about the Cessna 402, it apparently has a normal range of around 1,273 nm (1,467 mi, 2,360 km), compared to a distance Hawaii-Oakland of 2050nm (2359mi, 3797km). Hence, you're going to have to install additional fuel tanks and fly pretty heavy.

There a few considerations if you get a problem:

You will have to descend since the engine can't generate enough thrust at that cruise altitude. I found a source stating the ceiling for both engines is around 26180 ft compared to 11320 ft for one engine.
The fuel consumption increases in the remaining engine and will be greater than the total for both engines for the same flying conditions.
You're going to have to run the remaining engine hard for the remain of the flight.
If your temporary ferry tanks screw up (or any of the normal ones for that matter as well), you won't make it.
You may damage/break the gear if you have to return to the airport overloaded. "I once saw a Cessna 402 parked on the ramp at Honolulu with the gear punched half way up into the wings from a poorly executed overweight landing." Source

I can't do a calculation on for what portion of the flight you would be 'screwed' but I imagine it might very well be a bit of the journey. Several people seem to be in the opinion it's a pain to fly heavy and difficult to with one engine.


Why do budget airlines not use the jetbridge that's right there?

The answer to the question you link explain many of the reasons. But aside from them, all valid, the main point is that the use of jet bridges is charged an extra fee from the airport. Some airport charges for use, some charges for time, so a low cost company which is trying to save money is going to save on the jetbridge too.


What is the meaning of sub-paragraph 3-9-6 j. in FAA JO 7110.65X?

If you search for the words "opposite direction" in the order it seems clear that they simply mean what they say, e.g. 3-9-7(a)(1):

  Separate a small aircraft weighing 12,500 lbs. or less taking off from
  an intersection on the same runway (same or opposite direction
  takeoff) [...]

This is confirmed in JO7210.3AA, Facility Operation and Administration:

  2−1−31. OPPOSITE DIRECTION OPERATIONS

  Opposite Direction Operations consists of IFR/VFR Operations conducted
  to the same or parallel runway where an aircraft is operating in a
  reciprocal direction of another aircraft arriving, departing, or
  conducting an approach.


Other airport questions have been answered here and the FAA seems to have been involved in early regulations so Id say this is in scope here.

Airport security is a bit older than the 70's. The first serious criminal  aviation incident occurred in 1955 but hijacking has occurred since the dawn of aviation with cases being recorded as far back as 1930. The first serious increase in security appears to have come in 1961 (bolding my emphasis)

  Antulio Ramirez Ortiz hijacks a National Airlines flight to Cuba after
  it takes off in Florida. It is the first aerial hijacking of a U.S.
  passenger plane.

  The U.S. government begins placing armed guards on commercial planes
  when requested by airlines or the FBI.

If you follow the citation in the metal detector wiki it sounds like the FAA started to make mandates in the early 70's following the DB copper incident but it clear things were happening before then.

  But sky marshals couldn't ride on every flight, and the hijackings
  didn't end. So in December 1972, the FAA gave the airlines one month
  to begin searching all passengers and their bags. Dennis O'Madigan,
  then Director of Security for Piedmont Airlines, says metal detectors
  known as magnetometers were rigged up from a device originally used by
  loggers.

You should also keep in mind that in the earlier days of aviation ticket prices were extremely high and traveling via air was not as accessible as it is today thus some level of security was closer to what we see on private jets today. As ticket prices came down and the popularity grew greatly security became more of a concern.

On a similar note airport security has varied over time around the world. El Al the flagship carrier for Israle has generally implements security well above what most others are doing.

As for your pictures, the first one is dated 1970 which is in line with the timeline following the slew of incidents in the late 60's and the FAA's mandate of metal detectors in 72. The second picture is a bit of a mystery, it could be mis-labeled or they could simply be asking about weapons leaving the country as Switzerland historically has fairly liberal firearm laws and many other countries do not. The third photo looks staged or like a special situation, you can even see another photographer in the background. The Woman may in some way be famous (I cant identify her) and appears to be posing. That also looks like an EKG or polygraph machine...


Are low wings less safe for aerobatics training?

No.

It has nothing to do with the configuration, but the structure, the engine and the fuel system of your aircraft. The SportCruiser is certified in the Light Sport Aircraft (LSA) category and is meant for flying right-side-up. For aerobatics, you need

a fuel system than can still feed the engine when the load factor is less than or equal to zero,
an engine which can still lubricate all moving parts when it is experiencing a negative load factor, and
a structure which can tolerate higher load factors than what you can expect from cruising along at 115 kts max in fair weather.

The wing location has no impact on aerobatic fitness. You might even argue that the unrestricted view up in a low wing aircraft helps to see better what is ahead in steep turns.


What was the range of a low-frequency radio range station?

[Ex-avionics engineer, but not old enough to have worked on this ;)]

It's not so much the power of the station that determines the range, although it does of course impact the range.  The more important factors derive from the wavelength (which is a factor of the frequency).

The wavelengths of low frequency radio are in the order of metres to kilometres.  Signals at wavelengths of this order are subject to a lot less attenuation in the atmosphere since the stuff in air (dust, moisture, air movement due to thermals and wind etc) impact much less on a signal whose wavelength (the distance from peak to peak in the signal) is so large.

They are also subject to the effects of ground wave which means that the signal can follow the Earths' curvature and therefore travel way beyond the normal line of sight, up to a thousand miles or more.

They are also subject to ionospheric refraction or "sky wave".

The effects of the latter two depend a lot on night or day, sunspot activity, weather and so on but safe to say that sufficiently powerful signals ( a couple of kilowatts or so which is relatively small) in these ranges will be receivable over hundreds of miles and sometimes over a thousand miles.

The other frequencies look like 4 VHF and one UHF.  I'm sorry.  I have no idea what these are. My guess is that they are for tower, area etc in some order dictated by the plate legend.


What is the correct phraseology for "runway 03 R”?

Runway 03 R would be pronounced as

  Runway Zero Three Right

As ever, although British, I thoroughly recommend CAP 413 the UK's Radio Telephony manual:

https://publicapps.caa.co.uk/modalapplication.aspx?catid=1&pagetype=65&appid=11&mode=detail&id=6973

It's mostly ICAO compliant and barring small differences, should contain plenty of information for most operations. You'll see all runways are stated using two digits. Unfortunately I can't find an example of parallel runways in there.

One important note

  Runway Zero Three Right

Designates runway 03R, as opposed to runway 03L.

However,

  Runway Zero Three Righthand

Designates runway 03 and a right hand circuit. Very different things! In real life the chance of confusion is fairly slim, but it's worth noting.

  Is there any standard or preference of one form or the other to reduce confusion during communication?

Absolutely. Considerable effort has gone into the standardisation of air traffic communications in order to decrease the risk of misunderstanding. Page 6 onwards of CAP413 above goes into excruciating detail about how to utilise numbers, for example.


How are aircraft transported to, and then placed, in an aircraft boneyard?

Most are just flown in to Davis-Monthan AFB and then towed over to the boneyard where they're 'pickled'.  There are a couple different levels of preservation depending on it's potential future (returnable to flight, parts, etc.).  More information is available at the AMARC web site.


How are the runways operated at Toronto Pearson?

According to Toronto Pearson's official website, the airport operates in four main configurations, this is what they look like:

Also judging by the satellite imagery, CYYZ is LAHSO enabled, that is the intersecting runways (05 and 33L, for example) can be used simultaneously. (It resulted in a near-miss back in 2002.)


What are the must-checks for purchasing an airplane?

There are plenty of great $20,000 aircraft out there - the hard part is finding them.

"What to look for" is an incredibly broad question, and varies substantially between different types of aircraft: You would not look for the same things on a Piper Comanche as you would on a Cessna 182.
Accordingly the first thing you want to do is find a mechanic who is an expert in the particular type of aircraft to help you check it out and do a "pre-purchase inspection".

Finding those mechanics is actually pretty easy: Look for a "type club" that supports the aircraft you're considering and ask them for recommendations (e.g. for a Cessna I'd talk to the Cessna Pilot's Association, for a Cirrus COPA, for most Piper aircraft the Piper forum, for Beechcraft Beech Talk, etc.

Talk to folks on those forums (and to your mechanic) about what you, as a buyer, should be looking at before you get the mechanic involved for the more detailed inspection. There are lots of things you as a pilot (even a student pilot) can determine just by looking at a plane (and/or the logbooks).

Some key items to look at before you go see the plane:

NTSB Records
Like Larian mentioned go to the NTSB site (or the equivalent if you're not in the USA) and search for accident records. Not every accident will show up in the database, but sometimes you'll find out that the cream puff aircraft being advertised has actually been "substantially damaged" in an accident. The NTSB database search is free and there's no reason not to do it.
Logbooks
All aircraft have logs, so if possible get a copy of them before you even go to look at the plane.
Read through the logs (yes, all of them): You'll find all sorts of interesting things in there, but what you're mainly looking for is good, consistent maintenance and regular use of the aircraft. As a secondary concern you're looking for major repairs (or significant minor ones) that you might want to ask your mechanic about.
FAA Records
You can request a copy of the FAA's records for an aircraft online for a small fee.  This includes registration information and any records of major repairs/alterations ("Form 337") filed for the aircraft.  It is generally an "interesting subset" of the logs.
This is something you'll want to have handy when your mechanic looks at the plane, though it's not something you need to have before you go look at it yourself. Theoretically the owner should have all the documents that this record contains as part of their records/logbooks, but in practice paperwork sometimes gets "lost".

If all that looks good it's time to look at the plane:

How is the overall condition of the aircraft?
Cosmetics can lie, so don't be dazzled by a shiny coat of paint and a nice interior:

Is the on-board paperwork (ARROW) all in order?
Are the tires, hoses, and other rubber components in good condition?
Is the engine bay (relatively) clean? Are there any leaks, drips, or other items of concern?
Are there obvious signs of damage (skin patches, dents, fabric tears, etc.)?
Are there obvious signs of corrosion (bubbles under the paint, etc.)?
Is the paint in overall good condition (no major chips, no cracks, no flaking)?
Is the aircraft itself clean?
(As much as cosmetics lie, a plane that looks like it's been neglected probably has been...)

Does the aircraft pass a very thorough preflight?
Go through the preflight checklist with an eye for anything abnormal -- ask yourself "Would I fly this aircraft today?".
If the answer is no, think carefully about why.
If the answer is yes it may be time to test-fly with the current owner.
Does the aircraft operate correctly on the test flight?

Do the engine and propeller operate properly?
Do all the instruments and avionics function correctly?
Does the aircraft fly well? Can you trim for hands-off straight and level flight?

If the aircraft passes all your checks it's time to turn your mechanic loose on it - they will inspect the aircraft for problems (major and minor) that you as a pilot might not notice which can wind up costing you a lot of money. This pre-purchase inspection (and the ensuing negotiation based on what the mechanic finds) is usually the last stop before handing over your money and taking the keys.


What helicopter has the most rotor blades?

Special mention for Raúl Pateras Pescara de Castelluccio (good article) who was fond of lots and lots of rotor blades, settling on sixteen for most of his designs, although his Model 3 had twenty.

Pescara's helicopters may look a little comical (and dangerous!) but they are an important part of early helicopter evolution, pioneers in the first fully controlled helicopter flights, as well as the first use of the what would be recognised as modern helicopter controls.

Here's a video of Pescara testing one of his helicopters in 1922 wearing a Homburg hat with about 5mm of clearance to his head. He had many setbacks, but persevered. It's visionary, brave guys like him who make advances in aviation.

Plus, loads of blades.

Here is his Model 3 from 1929:
(source1)


Did any aircraft ever use stick twist for rudder control?

Yes, the RAH-66 Comanche FBW system used a twist control for the yaw channel.
The RAH-66 Comanche used a twist in the pilot's stick to control the rudder/yaw inputs.  It had no rudder pedals.  (Yes, a helicopter is an aircraft).
Comanche unfortunately was canceled near the end of LRIP (Low Rate Initial Production) in 2004 as the program was moving into EMD (Engineering and Manufacturing Development). There were at least 2 prototypes flying at the time. Test and development flights took place from 1996 to 2004.
Extracts:

"... the RAH-66 Comanche design incorporated a 3-axis, limited displacement, uniquetrim sidearm controller [replacing cyclic and yaw pedals] for control of the longitudinal, lateral, and yaw axes. A proportional collective with approximately 6 inches of displacement was used. An enhancement tailored to the scout mission was the incorporation of limited control in the vertical (fourth) axis of the sidearm controller. This allowed the pilot to command stabilized climbs and descents with the altitude hold system engaged. This was used primarily for vertical unmask and remask maneuvers, which enabled the pilot to fly through the autopilot without even temporary disengagement."
— "Impossible To Resist" - The Development Of Rotorcraft Fly-By-Wire Technology (PDF—Paywall)

and

"The RAH-66 Comanche program has proposed 4-axis controller (Harvey, 1992), but this approach is now questionable."
— A Four-Axis Hand Controller For Helicopter Flight Control

(Source)

Note that either the '3 + 1' or '4 + 1' controller configuration would likely have been the ones decided on for the Comanche, on the basis that all the cockpit pictures that have been seen feature a sidestick and a collective stick, but no pedals.

As noted in the first text block (Impossible to Resist) the 3+1 (collective) was the final form, although the cyclic had some control authority in the vertical axis (as described). I added the emphasis in bold, and the note on "side arm controller" vs "cyclic" in brackets.


Does having lead-in lights in sight allow descent below MDA?

No, you may not descend below MDA having only the lead-in lights in sight.
Reference FAA Order 6850.2b, "Visual Guidance Lighting Systems", page 1-3 through 1-5.
According to this order, the list of approach lighting systems is as follows:

Medium Intensity Approach Lighting System (MALS).

Medium Intensity Approach Lighting System with Sequenced Flashers (MALSF).

Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights (MALSR).

Simplified Short Approach Lighting System with Runway Alignment Indicator
Lights (SSALR).

High Intensity ALS with Sequenced Flashers (ALSF-2).

Omnidirectional Approach Lighting System (ODALS).

The Lead-In Light System is not in this list.  Instead, it is found further down the page.  Here's the key sentence:

The LDIN may be terminated at any approved approach lighting system, or it may be terminated at a distance from the threshold compatible with authorized visibility minimums permitting visual reference to the runway environment.

The LDIN is not an approach lighting system and so you may not use it to descend below MDA.


Does angle of attack change in a sustained climb?

We have seen that

  A climbing aircraft needs less aerodynamic lift than in horizontal flight, not more.

this means that if we keep constant airspeed and if we do not alter the configuration, the angle of attack will be (slightly) smaller, at least until the air density does not change.

As your assumption is that

  You apply full power

to enter the sustained climb, you will have even more thrust during the climb, and this will reduce even more the needed lift. This, together with the fact that you are slightly accelerating, reduces even more the angle of attack.


How wide would an A330's wingtip vortices be around a minute after landing?

Vortices of large aircraft often move laterally at speeds of 2-3 knots when they sink to within 100-200 feet of the ground.
In calm wind conditions, vortices created by large aircraft during landing operations can remain for many minutes over the normal touchdown area. They can also slowly drift from one runway to a nearby parallel or crossing runway. (NASA; emphasis mine)

and

Source: FAA

Using the two pieces of information above, the vortices start moving laterally at say T+15'. At T+60' (45 seconds later) they would have covered a lateral distance of 150–225 feet. In windier conditions they would travel farther downwind but dissipate quicker.
The day the video was taken (July 23rd, 2016) there were winds in daytime but almost all the reports having the direction variable, e.g.:

EDDF 231150Z 03005KT 330V110 9999 BKN023 SCT080 24/18 Q1017 NOSIG=

Assuming for the sake of simplification that the variable wind lessens the travel/dissipation, and plotting 650 feet (225 each direction + ~200 feet wingspan) on Google Earth on the affected runway, this result is shown below.

The core is surrounded by an outer region of the vortex, as large as 30 metres in diameter, with air moving at speeds that decrease as the distance from the core increases. (CAA New Zealand via skybrary.aero; PDF)

For the core diameter above, that would be a radius of ~50 feet at each end for a large plane.

About 3,200 feet down runway 18


How is an aircraft designed to be longitudinally stable?

My short answer:

Stability is controlled by moving the center of gravity (CoG).
The handbook should give center of gravity limits. A more forward CoG means a more stable airplane.
Shifting it past the neutral point makes the airplane unstable, so movements away from the trimmed state are accelerated. However, at supersonic speed this airplane will become stable again.
Airplanes with sophisticated computer control can artificially augment stability, so they behave like a stable airplane at all speeds.

For the long answer, let me first clarify terms:
Static stability is the tendency of a system to return to it's old state after being disturbed. Take a pendulum: If you pull it to one side, it will return to the middle. Eventually.
Dynamic stability is the tendency of an oscillating system for the oscillations to die down over time. Take the same pendulum: It will swing from side to side, and  friction will ensure this happens with ever smaller amplitude.
Now we need to add dimensions, all three of them: Pitch, roll and yaw. An airplane can be stable in one dimension and unstable in a different one. I understand your question such that you ask about the static pitch stability (or longitudinal stability) of fighter aircraft.
The Wright Flyer was longitudinally unstable (see here for more). Once aircraft designers learned that aircraft can be made to fly stable, and learned that this is of immense benefit in pilot training, static stability became a requirement for new aircraft. When war in Europe broke out, the British forces were equipped with a superb training aircraft, but it was so stable that it took effort and time to convince it to change course. They were shot down in droves.
From now on, low stability was a prime requirement for fighters and aerobatic aircraft. Static stability is proportional to the control forces (more precisely: To the hinge moment of the respective control surface), so reducing stability gave pilots more response for the same effort. Longitudinal static stability is measured as the relative distance between neutral point (NP) and the center of gravity (CG). See here for more. Longitudinal static stability is achieved by placing the CG ahead of the NP. Shifting the CG back gives you a more responsive airplane, but also one which is more easily disturbed by gusts.
This is the design technique you asked about. Pretty simple, right?
Once you shift the CG aft of the NP, stability is lost and the airplane will increase deviations from the trimmed state. This can be helpful if you want large angle changes, and quickly. An unstable aircraft only needs a small kick and will do the rest of the maneuver all by itself.
This is how it helps in maneuverability. But it is even more helpful to reduce the inertias, especially around the roll axis, for a faster response. That is why all combat aircraft have their engines close to the center.
Of course, negative stability is not acceptable when you need to take your hands off the stick to get a map out or to pee on a long flight. So without computer control, the limit was a CG position near, but not aft of the NP.
With supersonic aircraft, things get more complicated. Now the aircraft operates in two flight regimes, one where lift acts at the quarter chord of the wing and one where it acts at mid-chord. Aircraft with low static stability become very stable in supersonic flight, and the tail surface has to create a high down-force so that the sum of all lift stays where the CG is. Creating lift always incurs a drag penalty, and in supersonic flight it has to be payed twice: One for the excess lift on the wing (which is needed to compensate for the tail's down-force) and one for the down-force on the tail.
Using a flight control computer offers the possibility to allow the pilot to let go of the stick without the aircraft going off course. Now the stick does not command elevator deflection, but pitch rate, and the CG can be moved back from maybe 12% of MAC (mean aerodynamic chord) to -2%. If you compare the wing areas of stable and unstable jets (Jaguar and Mirage F-1 are prime examples), you will see how much is achieved just by going back with the CG by a few percent of wing chord.

Conventional SEPECAT Jaguar and CCV version (picture from Ray Whitford's Fundamentals of Fighter Design). Both configurations have the same airfield and combat performance!
These airplanes are unstable without computer control at subsonic speed. This is no benefit in itself (for better maneuverabiliy it helps more to reduce inertias, as explained above), but it dramatically cuts trim drag at supersonic speed. In supersonic flight such an aircraft is still stable, but much less than one that is also stable at subsonic speed. This means less lift is needed on the wings and less downforce is created on the tail, so the drag of botch surfaces is small and their size can be reduced, too, resulting in a virtuous circle of drag savings.


Does an airport need to have at least one instrument approach that I can use in order to fly IFR to it?

Under Part 91, you can file IFR to any point in space, including an airport without an instrument approach. But that doesn't mean you'll be able to land there.

FAR 91.175(a): "Unless otherwise authorized by the FAA, when it is necessary to use an instrument approach to a civil airport, each person operating an aircraft must use a standard instrument approach procedure prescribed in part 97.."

What ATC can do is clear you to that point in space at their lowest vectoring altitude there. If, when you arrive, the conditions are VFR, you can cancel your IFR and land. If not, you have to go somewhere else, possibly the alternate airport you would be required to have filed in your flight plan. And it's that alternate airport that MUST not only have instrument approaches, but have weather forecasts and reports high enough to meet the alternate minimum requirements of 91.169(c).


Why are the tips of the flap track fairings painted red?

Elaborating on Peter Kämpf's comment: The flashy tips are for preventing accidents during ground handling operations, e.g. by belt loaders. This can be a painting or an adhesive tape (possibly reflective, useful at night).

According the pages referenced below, this is done for the A320 family aircraft for which the flap track canoe fairings are not low enough to be obvious, not high enough to not cause a problem.

It seems this is a company decision not required by regulation. Several airlines do it.

Variations on the painting (taping):

Only the fairings close to the locations where ground handling personnel works.
Only the right side of the aircraft.
Also the winglet.
Color used: Red, bright pink, reflective green.

Photo Taha Ashoori on Airliners.net (source)

Photo Vin Lane-Kieltyka on Flickr (source)

(Source)

References (non authoritative):

Air Canada Flap Track Fairing Speed Tape? (Airliners.net).
Why Do Airliners Paint Trailing Edge Flap Fairing (Airliners.net).
Colour On Flap Track Fairings (Airliners.net).


Has a fixed-wing aircraft ever been built that featured multiple turbines powering a single propeller?

The LearAvia LearFan 2100 used two separate PT-6B to drive a single pusher propeller through a common gearbox.

LearFan 2100 in flight (picture source)

If you want to know why its official first flight date is December 32, 1980, read here.

LearFan 2100 engine arrangement (picture source)

This engine arrangement was the LearFan's eventual undoing when the FAA denied it a proper certification because of concerns that the single gearbox constituted a single point of failure.


Is the airspace at KUGN class G from the surface to 1200' AGL where class E starts when the tower is closed?

SVC means Service, not Surface, that would be SFC. 1200-0200Z is a time range, that means the zone is class D between 12:00 UTC (that's what the Z or Zulu time means) and 0200Z, which would translate to 07:00-21:00 local daylight savings time in Waukegan. Basically, the tower is open during those times and then it closes so it becomes a class E zone, traffic would presumably use unicom if the airport is still open.

The zone is not defined in the sheet, you'd have to look at a chart to get the details on size, shape and how high it goes.


Does making a mistake mean you lose your cert?

Probably not.  Depending on how poor your planning was (or appeared to be) you may have nothing happen, have letter placed in your file (not a violation), receive a violation, have to make a 709 ride with a Fed, or have your cert suspended, or maybe even a combination of some of these.

If you were a real goober and just went flying without checking fuel, and then lied about checking fuel, and then get caught lying to federal investigators then, yeah, revocation is a realistic possibility.  They don't like liars.  They can deal with stupid mistakes, but they will not tolerate a liar.

//thanks for the edit but was written as a runon//


What does the ATC instruction "Make left traffic, runway 19L" mean?

'Left' or 'right' traffic means that when you are flying the traffic pattern, all turns are to that direction.

The wikipedia article on traffic patterns isn't bad, and has some decent graphics, including this one from the FAA's Handbook of Aeronautical Knowledge:

The top pattern is left traffic, while the bottom pattern is right traffic.


Why does the P-51 Mustang takes so much altitude to recover from a spin?

Others can probably give you more precise info since I'm not a P-51 pilot, but I am studying aircraft dynamics in school right now, so maybe this will help.

Many fighter aircraft are designed such that they are very agile. This is especially true with roll dynamics, where modern fighters are even designed to be inherently unstable. They can then roll faster since the dynamics promote the roll. For roll stability, the wing design is often the main concern. Now, to spins.

I believe spins are mainly a yaw-plane event (though I'm sure there is some coupling of the equations). this means its a rapid rotation about the z-axis, the axis normally considered down. For stability, or desirable spin recoverability characteristics, the tail design is key. I don't know all the details or considerations behind the P-51's tail design, but any number of things could cause slow spin recovery, meaning you need to fall for a while (sorry, pilot!)

For example consider the distance between the tail's centroid and the overall plane's center of gravity. Imagine we added a lot more fuselage, basically extending the tail farther out. Now, with our extended tail, we have a different system. a really long tail might be too resistant to any yaw - basically it wants to got a certain direction, like an arrow.

Now, shorten the body instead, making like a short little squished P-51 with the tail right behind the pilot(shorten the arrow). while flying, the tail now might not help the plane fly very straight, at least not easily.

Finally, put the tail in front of the pilot and try to find anyone brave enough to fly it! No one will want to, because they won't make it home. its like shooting an arrow backwards, or throwing a paper airplane backwards- the dynamics of the vehicle just aren't favorable - any sort of deviation and the instability induces more deviation.

Thats only one part of tail design. You also need to consider size, number of tails, control surface size, and this doesn't even include the yaw dynamics that come from the rest of the plane in a spin.

I apologize if you already understood all that, but maybe it would help with my key idea. That is, that the reason it takes so long to recover from a spin is due mainly to its tail design. I don't know specifically how they designed it, or what design goals they were looking for, but because of what they chose, maybe considering manufacturing ease, structural considerations, aesthetics, drag, turn performance, weight, heck, maybe they just sketched it up and tried it, they ended up with a plane with this yaw plane recovery performance. It might be bad, but maybe their other design goals were met and they chose to live with it.

Other aircraft with better spin recovery performance will likely have different tail features like larger control surfaces, different tail volume... Overall, their tail design will give it better yaw stability and authority (control power available) to recover sooner.

Its late, and I'm sure I've missed things. I hope others can chime in and fix anything I may have mistaken. Let me know what I can add to improve my answer


Are there any specific weight or structural reasons to choose low vs. high wings for a cargo aircraft?

@Ron Beyer has pointed you in the right direction.  Study existing designs going all the way back to the Gigant.

The wing is by far the strongest part of the aircraft as it must carry leveraged aerodynamic loads and the weight of the aircraft while flying. A low wing may be slightly stronger to positive G loads as the fuselage forms an arch over the middle of the wing.  However, for cargo transport the high wing offers the advantage of a lower set, roll through cargo bay and more stability in flight.

As far as landing gear, the low wing offers placement
of gear on wings for wider track. High wings mount theirs in the fuselage, but the high wing offers the opportunity for greater ground clearance of obstacles on "unfinished" landing strips.

As you can see both are made and both are in service worldwide.  Commercial freight would favor the 747 type, military the C-17.  And let's not forget turboprops for fuel efficiency!

Both high and low wings will fulfill the requirements for cargo hauling, what about both on one plane to get wingspan back under 150 feet!.


What about an airfoil's shape makes air flow faster around it?

The flow of a viscous fluid can be described using the Navier-Stokes equations. This includes describing flow of air around an airfoil. Your assumption about conservation of momentum or energy is correct, both of these enter in the derivation of Navier-Stokes, together with conservation of mass:

[The Navier-Stokes Equations] describe how the velocity, pressure, temperature, and density of a moving fluid are related. [...]
The Navier-Stokes equations consists of a time-dependent continuity equation for conservation of mass, three time-dependent conservation of momentum equations and a time-dependent conservation of energy equation.

(NASA, emphasis mine)
Since there is no generic way to analytically solve Navier-Stokes, numerical approximations are typically used to derive a solution (see Computational Fluid Dynamics). When solving for the flow around a wing, the solutions show faster flow at lower pressure above the wing and slower flow at higher pressure below the wing. This might not be the simple answer you are looking for, but any answer that does not involve complex maths usually oversimplifies something.
While you are right that Bernoulli's principle relates the speed of the flow and its pressure, you have to be careful about implying causality from this:

Bernoulli-only explanations imply that a speed difference arises from causes other than a pressure difference, and that the speed difference then leads to a pressure difference by Bernoulli's principle. This implied one-way causation is a misconception. The real cause-and-effect relationship between pressure and velocity is reciprocal.

(Wikipedia)
To understand why airfoils are shaped the way they are, I recommend you have a look at the NASA page on Aerodynamic Forces. They have a good description of how the total force is generated from the pressure difference:


As a US citizen living in Europe, must I use a trust as the owner of an N-reg aircraft?

As a US citizen you can own an N-reg aircraft directly, regardless of where you live. The regulations on aircraft registration are in 14 CFR Part 47. They say who can register an N-reg aircraft, but they don't say anything about where that person must be. 47.3(a)(1) simply says:

§47.3   Registration required.
(a) An aircraft may be registered under 49 U.S.C. 44103 only when the
aircraft is not registered under the laws of a foreign country and is—
(1) Owned by a citizen of the United States;

The regulations are summarized in a more readable way on this FAA site. A trust allows a non-US citizen (or non-resident alien) to own an N-reg aircraft provided they have no more than 25% of the voting rights in the trust, per 47.7(c)(2)(iii).


What types of data can be extracted from a non-motion flight simulator?

It will depend on the representativeness of the modeling.

If your fuel system model, your engine model, and your aero model are representative of the aircraft, whatever is the qualification of the simulator, you will have good results. However, it will never be as accurate as the aircraft because of the unprecision of the modelisation and the fact that we are not able to modelise the thermodynamic part of the engine. We are using tables to get that and it creates a lot of inconsistency.

For example, if you try to look at the engine consumption in cruise it will be pretty accurate, but during acceleration phases, it will not be accurate at all due to the inconsistencies.

A simulator qualified as FNPT II + MCC under EASA or Level 5 under FAA should have the same representativeness as a Full Flight Simulator Level D for all the models talked above. So it will give you a good idea, but will never be accurate. However, it is still the best you can have from a simulation.


Why do lower molar mass rocket exhaust products give higher specific impulse?

Your question is slightly confusing. What you seem to ask is why, given that momentum is proportional to the energy, and speed increases only with the square of the energy input, a heavy rocket fuel is so much worse than a light fuel.

For a rocket, the speed of the burnt gases exiting the nozzle is important. Heavy molecules need more energy for the same acceleration, so the lighter the rocket fuel is, the higher are the nozzle speeds. Momentum is less important, because the mass of the fuel is on both sides of the equation: Heavy fuel in the rocket's tanks needs more energy for the same acceleration, and the chemical energy of the fuel is not proportional to its molecular mass.

Thrust is mass throughput times exit speed. For a given mass, thrust can be increased if the exit speed can be maximized. Since this mass must be accelerated, the total fuel mass needs to be as small as possible, not the number of fuel molecules (as your question implies). As you say, using lighter molecules helps to achieve this. The only problem is that lighter fuels need more volume, so a hydrogen rocket is bigger than one using alcohol (V-2) or Kerosene (Vostok).

To get the best specific impulse, the mixture in a hydrogen rocket engine is not stoichiometric, but uses only as much oxygen as required to heat up the gases up to their dissociation temperature. Adding more oxygen would set free more energy, but this would only be used up to ionize the combustion gases, not to heat them up more (Oberth effect).


What was the first aircraft equipped with a RAT?

So far, the oldest I have found is LZ-127 Graf Zeppelin, first flight in 1928. It used a propeller-driven generator to power its radios and a second one (with buffer battery) to keep the ship illuminated. In the drawing below (source) they are indicated as "Wind-Dynamo", being on both sides of the main gondola.

I am rather sure that the wartime Zeppelins used those generators as well, but have yet to find proof for it.

LZ-127 on August 26, 1929, in Los Angeles (source). The right generator is circled in red.

EDIT: Now I have found a source that attributes a RAT to the Zeppelin Staaken Riesenflugzeuge of WW I. The source is Tom Morrison's book "Quest for All-Weather Flight" and it says on page 28:

  In November 1917 the Drexler bank indicator was introduced instead [of the Anschütz gyro]. Much simpler than the Anschütz instrument, it weighed only 5 kg (11 pounds). It was powered by electricity from a generator driven by a small propeller in the slipstream and took less than a minute to run up to speed.

So this dates the first RAT back to November 1917. Sorry, no online sources.


Why are cabin doors outlined with a different color than the fuselage?

The doors are painted like this because it is a federal law that all cabin doors on commercial airplanes should be outlined in a color which contrasts with the fuselage color. It is done so that in case of an emergency on ground, rescue crew can find the doors easily and open them quickly.

It happened in past years that passengers survived some crash landings (especially at night) but perished because the rescue crews could not locate the cabin doors in time to rescue them from the burning airplane. The contrasting outlines of the doors allow them to find the doors instantly.

Here is the actual text of this federal regulation:

14 CFR 25.811 (f) Emergency exit marking

  (f) Each emergency exit that is required to be openable from the
  outside, and its means of opening, must be marked on the outside of
  the airplane. In addition, the following apply:

  (1) The outside marking for each passenger emergency exit in the side
  of the fuselage must include a 2-inch colored band outlining the exit.

  (2) Each outside marking including the band, must have color contrast
  to be readily distinguishable from the surrounding fuselage surface.
  The contrast must be such that if the reflectance of the darker color
  is 15 percent or less, the reflectance of the lighter color must be at
  least 45 percent. “Reflectance” is the ratio of the luminous flux
  reflected by a body to the luminous flux it receives. When the
  reflectance of the darker color is greater than 15 percent, at least a
  30-percent difference between its reflectance and the reflectance of
  the lighter color must be provided.

  (3) In the case of exits other than those in the side of the
  fuselage, such as ventral or tailcone exits, the external means of
  opening, including instructions if applicable, must be conspicuously
  marked in red, or bright chrome yellow if the background color is such
  that red is inconspicuous. When the opening means is located on only
  one side of the fuselage, a conspicuous marking to that effect must be
  provided on the other side.


Do pilots use the pedals in flight on planes with a sidestick (Airbus)?

The rudder pedals are not usually used in flight, even with the autopilot off.
The rudder on the Airbus A320 can be controlled via a mechanical connection to the rudder pedals in the flight deck, but also electrically via the fly-by-wire mechanism. The following graphic shows an overview of the rudder control:

(Airbus A320 FCOM - Flight Controls - Description)
As you can see the sidestick input goes to the ELAC (ELevator Aileron Computer) and from there a Yaw Order is sent to the FAC (Flight Augmentation Computer). This will then be passed on to the rudder via the Yaw Damper Servo Actuator.

Electrical Rudder Control
The yaw damping and turn coordination functions are automatic. The
ELACs compute yaw orders for coordinating turns and damping yaw
oscillations, and transmit them to the FACs.
Mechanical Rudder Control
The pilots can use conventional rudder pedals to control the rudder.

(Airbus A320 FCOM - Flight Controls - Description)
Since the yaw damping and turn coordination are fully automatic, there is usually no need for the pilot to use the rudder pedals in flight.
There are however some situations, where manual rudder input via the pedals is required:

Takeoff Roll: The rudder pedals move both the rudder and the nose wheel steering (NWS, see "NWS ORDER" in graphic above) on the ground to maintain directional control during takeoff and landing. After initiating the takeoff roll, the pilot flying (PF) will use the rudder pedals to control the aircraft:

The PF should use pedals to keep the aircraft straight. The nosewheel steering authority
decreases at a pre-determined rate as the groundspeed increases (no more efficiency at
130 kt) and the rudder becomes more effective.

(Airbus A320 FCTM - Normal Operations - Takeoff)

Landing: When landing the aircraft in a crosswind the direction in which the aircraft points is not aligned with the runway. To align the aircraft before touchdown (called de-crab), the PF needs to apply rudder input via the pedals during the flare:

During the flare, rudder should be applied as required to align the aircraft with the
runway heading. Any tendency to drift downwind should be counteracted by an
appropriate lateral (roll) input on the sidestick.

(Airbus A320 FCTM - Normal Operations - Landing)
This is the only time (for normal operations) where the rudder pedals are actually used in flight.

Engine Failure: After an engine failure the asymmetric thrust of the remaining engine needs to be overcome with the rudder. For an engine failure during the takeoff (but after V1), this needs to be done manually with the rudder pedals:

On the ground: Rudder is used conventionally to maintain the aircraft on the runway centreline. [...]
When safely airborne: [...] Since
the lateral normal law does not command the full needed rudder surface deflection,
the pilot will have to adjust conventionally the rudder pedals to center the beta
target. [...]

(Airbus A320 FCTM - Abnormal Operations - Operating Techniques)
Once the aircraft has accelerated, the rudder is trimmed and no pedal input is required any more.


If engines are closer to the wing (or in the wing) does it increase efficiency

Yes, mounting jet engines in the wing root increases aerodynamic efficiency due to:

No drag from engine pods
Smaller yawing moment upon engine fail, and resulting smaller vertical tail.

But that is about it. There is a host of disadvantages to mounting the engines in the wing root, one of them being that high lift devices cannot be used and the wing is bigger, causing more drag.

Three huge advantages of mounting the engines in pods, underneath the wing, in front of the aeroelasitc axes are:

High bypass engines can be mounted, vastly improving fuel efficiency.
The engines are within easy reach for maintenance.
The weight of the engines provides both bending relief, and reduces structural weight to prevent flutter.

Also see this question.


Are there dual pilot planes to pilot myself?

Yes, the vast majority of airplanes have dual controls. You can just call up your local flight school and explain what you want. A "Discovery Flight" is typically 30 minutes of flying, just to see if you're interested, but if you want to go for longer than that, just let them know beforehand.


How does an aircraft maintain level flight while accelerating?

Simply put, in the scenario stated, to maintain level flight the appropriate amount of nose down input would be applied.

As the op points out, the increase in speed through the air increases lift, and the AOA (angle of attack) needs to be reduced.  This is normally done with stick (or yoke) input, followed by trim.

On most aircraft the lowering of the nose would be accomplished by lowering the elevator (and/or raising the trim tab) on the rear horizontal surfaces.


Do real aircraft have something close to the GPS/NAV modes in FSX?

In the Boeing world, LNAV is Lateral Navigation, and VNAV is Vertical Navigation.

When LNAV is engaged, the autopilot will follow the Flight Management Computer (FMC) guidance laterally, i.e. left & right.  When VNAV is engaged, the autopilot will follow the FMC guidance vertically, i.e. climbs & descents.

LNAV is conceptually pretty simple: you have a magenta line on the map, your desired course, and the autopilot will follow it.  The points defining your course are database points in the FMC that may but certainly do not have to correspond with VOR's or other conventional NavAids.  You can use LNAV to fly VOR-to-VOR, or it can fly point-to-point-to-point equally easily.  (You don't have to tune any frequencies in either case.)

VNAV is a little more complicated, because you may only be cleared for some of what the FMC wants to do vertically.  Simple example: you're cruising at FL370, planning to start down at a given point so as to cross AAA at FL240, and then continue the descent to cross BBB and 10,000' and 250 knots.  ATC clears you to "descend at pilot discretion, maintain FL 290."  That means you can start down at whatever point you want, but until you get cleared lower later on, you can't descend all the way to FL240 or 10,000.  Yet.  Or maybe the controller needs to put you at FL350 right now to avoid a traffic conflict 100 miles ahead, and your clearance is "descend now and maintain FL350, pilot discretion FL290."

It's a lengthy section of Ground School how the pilot sets up the FMC and the mode control panel to accomplish all of this, but hopefully that illustrates some of the complexity of VNAV.

It's a good system; under typical conditions you can go into LNAV and VNAV shortly after takeoff and stay in them both until shortly before landing, and the FMC gives you smooth (mostly) and efficient guidance.


Transonic buffet - reason for a rapid movements of the shockwave along the wing chord line?

Viewing the airfoil as a rotating cylinder, the highest velocity on it's surface occurs at the top of the cylinder (90° using polar coordinates) therefore that's where the shockwave begins and hence where flow separation will start

I know that as the free stream velocity gets higher the point at which the velocity on the surface on the airfoil (cylinder) goes supersonic occurs closer and closer to the leading edge therefore the first tendency of the shockwave is to move "forwards" (towards 0° on the cylinder representation)

I also know that flow separation occurs under an adverse pressure gradient however between 90° and 0° the pressure gradient on a cylinder is favourable (due to geometry), therefore perhaps that is why the flow reattaches when the shockwaves moves <90°


Is there a simple relationship between angle of attack and lift coefficient?

In the post-stall regime, airflow around the wing can be modelled as an elastic collision with the wing's lower surface, like a tennis ball striking a flat plate at an angle. Lift and drag are thus:

$$c_L = sin(2\alpha)$$
$$c_D = 1-cos(2\alpha)$$

I superimposed those (blue line) with measured data for a symmetric NACA-0015 airfoil and it matches fairly well. I don't know how well it works for cambered airfoils.


In an articulated hub rotor craft, what could cause the blade to flap negatively?

The first thing that comes to mind does not occur in forward flight. That would be a hard landing. Depending on the rotor design and the amount of articulation and the landing gear type, a hard landing can result in some serious problems, notably, Ground Resonance.

In-flight, it may be possible to achieve with a rapid unloading of the rotor (Zero - G) plus cyclic input. One adverse condition which causes negative flapping is Mast Bumping. Usually, if not always fatal. Mast bumping takes a specific set of conditions and control inputs, to take place. It is typically occurs with 2 bladed teetering rotor systems at zero G.


Can a non-instrument rated safety pilot log PIC during an IFR flight?

No

The way that both pilots can log PIC is that the pilot using a view limiting device is logging PIC as sole manipulator and the safety pilot is logging PIC because he is acting PIC and a required crew member.

If the flight is operating under an instrument clearance then the acting PIC must be instrument rated. If only the pilot with the view limiting device is rated then he is acting PIC and is the only one eligible to log PIC. The safety pilot is also not allowed to log SIC as a required crewmember without an instrument rating while operating under IFR.

If you are in actual IMC then you shouldn't be logging anything and they other guy shouldn't be wearing a view limiting device.

If you want the PIC time ask your friend to fly VFR or get yourself an instrument rating.


What is this button (pressed during approach) on the Airbus A320?

This is the TERR ON ND button, or Terrain on Navigation Display. An EGPWS feature that paints the ND screen with the terrain. The color coding indicates if the surrounding terrain would pose a hazard if flown close to. The push button operation is:

At 46:10 in the video the TERR mode was off, the captain turned it on, pointed something out to the first officer, and turned it off. Zurich (the destination) has areas of high terrain around the airport.
(Source) Click to view.
The color coding and example:
Click to view.


Why would a C150 tachometer be sluggish?

No you don't have to "break in" flight instruments.

When a TSO'ed instrument is new it will get an Acceptance Test Procedure (a functional test) from the factory done before it is released and it has to perform to specification.  There is no such thing as a break in in service.

That being said, sometimes parts get by the ATP and malfunction in service, so you never know.  In my years in the regional airline industry, "bad from stock" is not uncommon even with super fancy Transport Category components.

Problems with the flex drive could be a factor, but a flex shaft would have to be binding and winding up a hell of a lot to create that kind of lag.  It's still something that could be checked.

Before that though, you should call Mitchell's tech support and describe what it's doing and see what they say.   Maybe they'll tell you there is a break in, but I'd be pretty surprised if they did.


Why does the 737 Original have an explicit hydraulic-quantity indicator for only the A hydraulic system?

Your question: Why doesn’t the Original have quantity gauges for both main hydraulic systems, rather than just for the A system?
On the B737 100/200 airplanes the system B hydraulic reservoir is filled from the system A reservoir.  So, when the system A gauge displays a normal quantity the system B reservoir quantity would also be normal (separate B quantity gauge not required).
If the B hydraulic reservoir "low quantity" warning light illuminated then the A hydraulic reservoir would be at a level of about 1.8 gals (balance line between the A & B reservoirs leaves fluid in the A reservoir if only the B system leaks) and its quantity gauge would indicate so. (and there would be a low quantity or total depletion of the B system reservoir also)
B737-300 airplanes and later models have a differently designed hydraulic system in this regard.


It used to be done launching crushed walnut shells into the running engine and the blades are polished by the process.  Known as Coke Blasting.  The process is uncommon these days.

Similarly they use a walnut shelll coated emery cloth to polish crankshafts after machining

http://www.dennisdawson.com/jetblast.htm

It is still commonly done on industrial turbines apparently


What is the exact responsibility of the Landing Signal Officer on an aircraft carrier?

An Landing Signal Officer (LSO) is a naval aviator with additional specialized training to better facilitate recovery operations on the ship.  LSOs provide guidance for aircraft making approaches to the carrier.  They monitor the approach and remain in contact with the pilot during the approach by radio.

Carrier approaches or 'passes at the boat', while analogous in technique to an approach to land at a terrestrial airport, require much more precision and have far less margin for error due to the landing area's small size (75 x 600ft). And the requirement that the jet must impact the deck on speed and on angle of attack within a small area to snag an arrester wire and trap successfully makes this even more difficult.

The Navy has adopted this policy of the landing signal officer as well trained LSOs can quickly dissect problems with the approach and alert the pilot to correct prior to the pilot even becoming aware that there is a problem developing.  Particularly insidious errors like settling in the groove or settling at the ramp leading to a dangerous rampstrike or liquid landing can be spotted by the LSO before the pilot even realizes its happening.

In addition to forcing each pilot to perform at their best, the LSO grades each pass.  Multiple LSOs observe the approach and comment on the elements of the approach e.g. Long in the Groove, a little fast, low at the ramp, etc.  These are used to assign the following grades to a pass.

OK UNDERLINE - perfect pass, only awarded in extreme circumstances or
emergencies. Worth 5 points.
OK - excellent approach. On lineup, speed and glidepath with minimal
deviations, each corrected for quickly.  Hook snagged the 3-wire.
This is the best grade assigned for normal operations. Worth 4 points.
(OK) - A fair pass, exaggerated deviations with delayed corrections,
but approach was safe and conducted properly.  Worth 3 points
OK-BOLTER - an an OK or (OK) pass where the tailhook did not snag a
cross deck pendant.  Worth 2.5 points.
NO GRADE - Approach was safe but had gross deviations and
unacceptable corrections. Worth 2 points
WAVEOFF - Approach terminated, either by the LSO or the pilot for a
variety of unsafe reasons e.g. foul deck, PIO, etc.  worth 1 point.
CUT PASS - Unsafe approach attempted by the pilot, generally after
refusing to comply with a waveoff instruction.  If you survive it,
you can probably expect to have your wings clipped in a Field Naval
Aviator Evaluation Board.  Worth 0 points.

Grades do matter.  A single bad landing or a bolter will get you a razzing by your squadron mates; habitual bad landings and low grades will get you a FNAEB and most likely reassignment to flying helos or to shore based aircraft.

At least four LSOs will be on hand to observe and grade landings.  This 'Wave Team' will consist of a Controlling LSO, who monitors glideslope and speed, ultimately assigning the grade, a Backup LSO, generally more senior than the Controlling LSO who monitors lineup and assists with grading, and a Deck Status LSO, who monitors the condition of the deck in order to provide a waveoff alert to both the Controlling and Backup LSOs.  A fourth LSO, the Airwing LSO 'Paddles CAG' will be on hand to observe and supervise the whole operation and mentoring junior level LSOs.  There are two Paddles CAGs on every cruise and at least one is on the platform for every recovery.

In the photo above you have a group of LSOs observing approaches during a recovery.  The wired wands that two of them hold are controllers for the waveoff and cut lights on the IFLOLS optical landing aid system to the left of the landing area.  These give visual cues of mandatory instructions from the LSO for a waveoff or for the pilot to cut their engines on the approach.  Each LSO is noting where the aircraft was during the approach vs where it should have been to get a consensus as to what grade and comments to assign to an approach.


What kind of dihedral would be most stable?

More dihedral doesn't necessarily make an airplane more stable. With too much of it, oscillations like the Dutch roll are not damped any more.

A polyhedral wing can be chosen for different reasons than just stability: With the dihedral of the outer panels, any angle of attack change there is reduced by the cosine of the dihedral angle. This means that the lift curve slope is flatter there and stall happens later. This is a great way to combine an almost elliptical circulation distribution with pleasant stall characteristics, similar to a raked wingtip, but using dihedral instead of sweep!

For the stability derivatives of partial dihedral I recommend to turn to no other source than Sighard Hörner's Fluid Dynamic Lift. In chapter XIV it shows a plot of a rectangular wing with an aspect ratio of 6 where the location of the onset of the dihedraled wing fraction is plotted over the X axis. This data is taken from NACA's technical report 548:

Figure 13 from Chapter XIV of Fluid Dynamic Lift by Sighard Hoerner. Note that it plots the derivative of a derivative on the Y axis!

The $c_{l_{\beta}}$ curve can best be approximated by a sine curve. Note that the Y axis shows the $c_{l_{\beta}}$ and $c_{n_{\beta}}$ derivatives over changes in the dihedral angle $\Gamma$. To arrive at your expression with constant tip elevation for different dihedral onset locations, the curves need to be modified by dividing them by the cosine of the partial span (assuming the root is 0 and the tip is $\frac{\pi}{2}$). This would yield a constant value for $c_{l_{\beta}}$, so the dihedral onset is of secondary concern and the dihedral effect depends on the tip elevation. Note: This is valid only for rectangular planforms - as soon as taper is involved, things get more complicated. This PDF has more on effective dihedral of tapered wings.

NACA TR 548 supports your opinion:

  The tests also showed that with dihedral only the outer one-fourth of
  each semispan, the dihedral effect was maintained to a much higher
  angle of attack than when the complete wing had dihedral.


Official way for tower to address all aircraft on frequency for new ATIS?

The tower will usually broadcast a note such as “Attention all aircraft: ATIS information Victor is now current. Wind two two zero at seven knots.  Altimeter three zero one four”.  This isn’t official phraseology and really isn’t required of ATC, but is a courtesy call to all pilots operating around the airport to retrieve the latest ATIS broadcast for reference.


Are there full scale helicopters capable of sustaining inverted flight?

There is no real helicopter capable of sustained inverted flight and certainly not of hovering inverted.

The simple reason is that there is no operational need to do so.

Is it theoretically possible?  Yes, but you have a lot of engineering problems to overcome.  In addition to inverted fuel and oil systems, the rotor head will be much more complex than it needs to be.

When flying normally, the fuselage effectively hangs like a pendulum underneath the rotor with a large nut (OK, it's more complex than that) holding the rotor onto the rotor shaft hub.  The rotor pulls the fuselage up.

To fly inverted, the rotor must be able to push the fuselage up so the hub would have to be engineered to apply and withstand the appropriate forces in both directions.

Then, the rotating blade cuffs, and associated hinges, must be designed so that the blades can have negative pitch (as seen from the normal attitude) across the full range.  In turn, this means that the collective mechanism must be designed so that it is possible to set positive and negative pitch as required.

The blades would also need to be more rigid, so that they do not cone excessively and contact the fuselage.  This would add more forces to the head joints which would need to be strengthened.

Finally, you must "reverse" the cyclic controls so that the expected collective pressure, cyclic back; nose up; reduce speed; works in the opposite sense.

I've probably not considered other factors.

All of this would add significant complexity and weight which, given that there is no requirement for inverted flight, will not happen.

By the way, the power required to fly or hover inverted would be the same as for normal flight.  There is no intrinsic reason why inverted flight would need more power - blades rotating at a certain speed, with a particular angle of attack will generate the same amount of lift no matter which way they are pointing.

The reason model helicopters can do this is that the ratio of the weight of the rotor to the weight of the fuselage is much lower than for a real helicopter, and therefore requires a lot less power to produce the required lift, and models have a much higher power to weight ratio.

The reason real helicopters can go inverted for a short time in aerobatic manoeuvres is because the momentum on the fuselage is pulling away from the rotor so that the lift vector pointing up, toward the fuselage, is countered. Consider an outside loop, which would be impossible, since the momentum of the fuselage and the lift vector would combine.

You should be able to demonstrate this in a model with a normally designed rigid head.  Add some (secure) ballast in the fuselage until you must accelerate in ground effect to gain translational lift in order to be able to climb out.  Now try to fly inverted!


Has anyone considered putting a hydrofoil on a sea plane?

Yes. I mean, sort of. Nobody's ever built a production hydrofoilplane.

It's not a bad idea, but seaplanes are a relatively niche product these days and there doesn't seem to be a lot of innovation in the field. Back when there was, there was innovation everywhere so the idea of hydrofoils didn't stick.

The Convair F2Y Sea Dart, a 1950s prototype jet-powered fighter, used two 'hydro-skis' for takeoff and landing. It was more or less awful compared to the crop of land-based aircraft coming along and after a prototype disintegrated they (probably wisely) chose to shut the program down.

There are some other prototype aircraft that used actual hydrofoils that I found after some quick googling. A company called Lisa Airplanes seems to have an LSA - the Akoya - that's under development using tech similar to the Sea Dart.

The 1929 Piaggio P.7 used hydrofoils, and was intended to compete for the Schneider Trophy, but never made it airborne. Interestingly enough it had a screw (marine propeller) at the tail and a proper aviation propeller up front, and the pilot would've had to do some juggling between the two.

It's likely there were others, but I'm running low on sleep.


What website(s) can I use to plan an IFR route along airways? WORLDWIDE

For the United States, Skyvector is easy and free.
Use the buttons in the top-right corner to switch to "World Lo", that will give you instrument charts.


Can general aviation use UHF to contact ATC?

The UHF air band operates in AM in a general range of 225.0–399.95 MHz. Many ATC functions have both VHF and UHF frequencies. For example, Newark Liberty Tower uses 118.3 and 257.6. ATC will often broadcast on both the VHF and UHF frequencies.
You can look up these frequencies on the FCC frequency allocation table to see who is allowed to use these frequencies. This is also located in CFR Title 47, §2.106.
According to the table, the the non-emergency allocation of these frequencies is Federal use:

In the bands 225-328.6 MHz, 335.4-399.9 MHz, and 1350-1390 MHz, the fixed and mobile services are limited to the military services.
The bands 235-322 MHz and 335.4-399.9 MHz are also allocated on a primary basis to the mobile-satellite service, limited to military operations.

There are no non-Federal uses cited for those ranges. Also, per Title 47 §2.102(c):

Non-Federal stations may be authorized to use Federal frequencies in the bands above 25 MHz if the Commission finds, after consultations with the appropriate Federal agency or agencies, that such use is necessary for coordination of Federal and non-Federal activities

So it seems that if you don't have a military purpose, outside of special agreements you are not allowed to use these frequencies. For more information, the National Telecommunications & Information Administration (NTIA) has reports on the usage of the lower portion and upper portion of this band.

Technically there are also limited non-Federal uses but they don't apply to this question:

The frequency 243 MHz is the frequency in this band for use by survival craft stations and equipment used for survival purposes.
...may also be used, in accordance with the procedures in force for terrestrial radiocommunication services, for search and rescue operations concerning manned space vehicles.

For the gap in the ranges mentioned above:

The use of the band 328.6-335.4 MHz by the aeronautical radionavigation service is limited to Instrument Landing Systems (glide path).

And additionally for 322-328.6 MHz:

...all practicable steps shall be taken to protect the radio astronomy service from harmful interference.


How does an outflow valve work mechanically?

The driving force for the valve is a vacuum source that is connected at the vacuum connection at the bottom of the diagram.  The valve operates by varying suction to chamber 3, creating a pressure differential between 3 and 1 (cabin pressure) that allows the pressure in 1 to drive the valve open (to the left in the diagram) against the return spring.  Take away the vacuum, and the spring will close the valve (move to the right).
The vacuum source is usually an ejector pump in the engine bleed air plumbing, so the vacuum is available whenever the bleed system is on.
So in other words, the valve is sucked open (by bleed-powered vacuum), and sprung closed, and is modulated by varying the suction (by the electropneumatic control valve) against the constant spring pressure.  More suction moves in more open, and less suction moves more closed, and if the suction is completely removed the spring fully closes the valve.
On transport aircraft there are normally two outflow valves for redundancy, but both will usually be located next to each other, typically at the rear pressure bulkhead, and all of the air in the pressure hull will exit at that spot, all of the pressurized zones being interconnected.  Where separated spaces are vented to each other in the pressure hull, but would have a hard time equalizing quickly in a rapid decompression event, like a cockpit bulkhead with the door closed, there will be special blowout panels (like in the cockpit door or elsewhere on the bulkhead) to allow equalization to occur rapidly.
You will also typically find a separate dump valve that opens on on the ground to keep the aircraft from being (slightly) pressurized by ground cart inflow when the bleeds are off and the outflow valves are closed (which can cause problems with opening plug doors), and also to provide an exhaust path for avionics cooling during ground operation with the main doors closed.
The opening size of the pressurization outflow valve has to be large enough to allow more air out than the maximum bleed flow in, so it has to have a fairly large exhaust opening to be able to control pressure at the margins with the pressure hull as airtight as it can be.
Aside from altitude, how much the valve opens in normal flight depends on the main air conditioning bleed inflow (which is usually constant, being regulated bleed flow) and how leaky the hull is (an older airplane with worn door seals, leaky rivets etc, can be quite leaky, and the valve may run pretty much almost fully closed some of the time because of all the air that is getting out through other points - if you've ever been at the forward galley area and wanted to hold your ears due to some crazy howling sound, that's a door leak, and the outflow valve will be running more closed than normal to compensate).


How does one calculate the taper ratio of a compound wing?

Taper Ratio is a simple geometrical metric that is valid for rectangles and trapezoids. If the leading edge and/or trailing edge of the wing is bent or jagged, Taper Ratio does not have a very useful meaning anymore. The Taper Ratio of the Concord wing in the OP diagram is zero.

For the compound wing in the OP diagram, the situation is a bit ambiguous as well. Is the wing root the projection of the leading edge into the fuselage, and is the extension at the root just an aerodynamic streak that uses the structural members of the main wing?

The definition of Mean Aerodynamic Cord uses wing root and wing tip as well, and is subject to the same complications. There are some pretty intricate graphs for wings wing a compound planform, this one is from Torenbeek.

If you would want to use Taper Ratio with a compound planform wing, the best average would be a weighted one, where for each of the wing planform segments the Taper Ratio and the area is determined, resulting in average TR per area.


Why do we have a booking code and a ticket number?

Part of it is a hold-over to historical systems (where airlines ran their own booking systems). Now that most airlines use a global system like Amadeus this is less of an issue.

The ticket number (PNR) and booking number (record locator) do have slightly different purposes though. The former contains the details needed for the actual flight (your name, contacts details, flight numbers, etc) while the record locator can also contain other information not directly related to the flight.
In short: The record locator contains a reference to the PNR but can also contain additional information that is not contained in the PNR.