What are some drawbacks to having a wingtip propeller on an aircraft?

Feathering isn't really an issue, if you can feather a prop on an engine further inboard you can do it on the tip too. There are 3 major drawbacks that come to mind:

The wing structure has to be stronger: engines are heavy, the further out they are the beefier the structure has to be to hold them. Stronger wings mean more weight and possibly a thicker cross section. Neither are good traits in a wing
Decreased roll rate: the farther the engines are the greater the moment arm and the slower your roll rate will be. Think about skaters spinning around, the farther their arms from their body the slower they spin. The same principle is at work here, so you need bigger ailerons to give you maneuverability, so more weight, cost and complexity
Safety in a single engine failure scenario: engines on the wingtips will cause more yaw in a single engine failure than engines further in board, so you'll need a bigger rudder to counteract it. A bigger rudder means more weight and cost, and there are also limits - eventually you will get to the point you can't counteract the force effectively and an engine failure will cause a loss of control. Yaw onset will be faster as well, giving a pilot less time to react, and there's nothing you can do about that; a bigger rudder doesn't help with reaction time. Mechanical cross-connections could be used to share power across the wing in the case of a single engine failure, like the V-22 Osprey, Chinook helicopter, however these increase weight, cost and complexity. Also, these systems aren't perfect, a single engine failure is still a possibility


Should 3 takeoffs and landings to stay day current be solo?

Yes you can count that time as PIC and towards this currency requirement.

The regulation requires that you are the only one who moved the flight controls during takeoff and landing. This means you could fly with anyone else in the cockpit (including a flight instructor, another pilot, or non-pilot friends) but you alone must be the person who performs those takeoffs and landings in order to remain qualified.

This eliminates a few scenarios from counting towards the currency requirement, including:

You flew with another pilot, counted yourself as PIC (because you were more qualified or by prior arrangement) but didn’t actually do the work yourself
You flew with an instructor, and they helped you with the landings


Is there any civil aircraft that decelerates with a parachute?

(airliners.net)

Some early civilian jets had drogue parachutes such as the Caravelle and the Tupolev Tu-104.

While the reverse systems are heavier than the parachutes, they are more practical (no stowing and running after rogue parachutes).

Regarding the edit for today's planes: they went out of fashion for the civilian jets.

For newly built jets, there aren't any as far as I know. Older jets that may still be airworthy, and military aircraft that may have been converted to civilian use, are not included in my assessment.

The weight saving makes sense for fighters which are range limited due to the high performance engines and the placement (and type) of the nozzle. The weight of a reverse system is better substituted with fuel or ordnance. The Saab 37 does have reverse though.

(Source) Parachute used for an attitude recovery system. It's not meant for decelerating though.

(Twitter) Norwegian F-35's will also have parachute brakes (related to the note on fighter generations).

Related and/or duplicate, you decide: Do any commercial airline models have a parachute at rear to help in landings? (Answers are more thorough and include gliders.)


What is a land and hold short clearance (LAHSO)?

It means that you can land on the runway but must hold short (read: do not cross) before some point on the runway.

AIM 4-3-11 Pilot Responsibilities When Conducting Land and Hold Short Operations (LAHSO)
6. A pilot who accepts a LAHSO clearance should land and exit the runway at the first convenient taxiway (unless directed otherwise) before reaching the hold short point. Otherwise, the pilot must stop and hold at the hold short point.

This is generally issued for smaller planes that don't need the full runway and a crossing runway/taxiway is also being used.
As the pilot you have final say in accepting the clearance, if you feel you will be unable to hold short then you should reply "unable" and request full-length landing clearance.

[same link as above]
3. The pilot-in-command has the final authority to accept or decline any land and hold short clearance. The safety and operation of the aircraft remain the responsibility of the pilot. Pilots are expected to decline a LAHSO clearance if they determine it will compromise safety.


Does a 1lb crow expend only 7.68 Watts to fly at 37 km/h?

The number cited by Orville looks quite reasonable. The crow is just cruising along, not banking, accelerating or climbing.

Now add a climb speed of just 1 meter (3.3 feet) per second, and the additional power is 5,93 W. Let it circle with 60° bank angle, which would double the required lift, and the power for staying aloft increases to 15.36 W.

Next comes the flight speed, which goes up with the root of the wing loading. The American crow has a wing chord between 25 and 33 cm and a wing span between 85 and 100 cm. Taking the average puts their wing area at maybe 0.25 m² (it is almost rectangular, after all), and their wing loading at 1.8 kg/m². I would expect that a battery-powered model would have a higher wing loading, maybe 5 kg/m². The required power goes up with the third power of speed, and the speed itself increases with the square root of the wing loading. This makes the model of the crow fly at 62 km/h and consume a power of 35.5 W - just for straight and level flight. Add some margin for acceleration, banking flight and climbing, and the 50W/lb rule looks quite reasonable.


This answer assumes you live in the United States. You should consider attending a Part 147 program at an Aviation Maintenance Technician School approved by the FAA. Some avionics technicians also get themselves an Airframe mechanic's rating from the FAA because a good percentage of what a line avionics technician does has to do with components of the airframe. (As a side note, military experience as a line avionics tech is considered sufficient to qualify to take the tests for the Airframe mechanic rating). You can also become certified through a repair station, but that may only qualify you to perform specific work. You should definitely also get the FCC radio-telephone operator certification or Aircraft Electronics Technician (AET) certification from the National Center for Aerospace and Transportation Technologies.


Why are TFRs issued around stadiums during games in the U.S.?

The 'stadium TFRs' were originally required by Congress after 9/11 to reassure people and encourage them to continue their normal activities without worrying about aircraft flying low overhead. And since then, Congress has repeatedly voted to maintain them; the FAA is just implementing them as directed.

There's more information in FAA Notice 8900.370:

  Following the events of September 11, 2001, Congress enacted
  legislation that restricted civil aircraft operations over sporting
  events such as NASCAR, Major League Baseball (MLB), the National
  Football League (NFL), National Collegiate Athletic Association (NCAA)
  Division I Football, and other open-air events containing more than
  30,000 people. These restrictions are implemented via a TFR. In 2004,
  Public Law (PL) 108-199, Consolidated Appropriations Act, Section 521
  was modified to allow civil aircraft limited use of designated
  sporting event TFR airspace.

The TFRs are generally very unpopular with pilots and perhaps as a result, there have always been rumours about other reasons why they were created, or - even if you accept the original reasons - why Congress insists on maintaining them today. For example, the NFL benefits from not having 'unauthorized' aircraft taking pictures or towing banners over their games, when they could be selling those rights exclusively for a lot of money. So perhaps the NFL has pressured Congress to maintain the TFRs for 'security' reasons, while the real motive is making more money. The same comments and thinking are often applied to the 'Disney TFRs', by the way.

Having said all that, there are some arguments that 'security theater' - i.e. feel-good measures that provide no actual security - can have a positive impact on people's comfort and confidence, so it's not a black and white issue. But that whole topic belongs on another site.


How to determine the maximum servo torque required for a nose gear?

Assuming that we are designing a steering system, for a single steering wheel aircraft.

The servo is yawing the wheel to a position. The position causes side force on the wheel. And that generates a yawing moment for the aircraft. (The aircraft can be moving in various directions, but assume you know the max side force required.)

This side force, multiplied with the distance of the wheel contact point and the wheel yawing axis is one major contributor to the servo torque. (Torque1)

Another contributor is the rotational friction of the wheel. Which is the resistance to yawing further. (Torque2)

Torque_total = torque1 + torque2.

This is the output torque for the servo mechanism. The mechanism will affect the torque on the servo shaft.


What is the feasibility of a Coanda/Magnus effect wing airplane?

A lot of research grants are wasted on scams or projects making exorbitant claims. See it this way: The people who judge an idea grant-worthy need to spend the money they have available somehow, and if they were clever enough to pick winners all the time, they would not work in a government bureaucracy.

On the other hand, who is to judge what idea is really good before it has been tried? You have to accept some losses if you want to move outside of safe bets - only then can new ground be broken.

NASA funded a researcher for more than three decades who was only working on joined wing projects. It's easy to see that they are a non-starter, but this guy built his career on that particular hoax.


For New Zealand1, the Airways Pricing Framework is a document which describes how the prices are set but not the actual prices themselves (that is in a different document that it appears you have to sign up to receive). Some excerpts:

Consistent with international practice and ICAO guidelines, Airways uses aircraft weight as the basis for its charges.
En-route charges also vary with distance flown. Intrinsic to the formulae is the principle that prices should be
transparent and practicable. A simple pricing system lowers Airways’ costs and those of its customers.

For IFR approaches:

For aircraft flying IFR, the greater of the Minimum Price or:

for aircraft weights under 5 tonnes = Base Rate x MCTOW / 5
for aircraft weights 5-30 tonnes = Base Rate + Weight Rate x (MCTOW – 5)
for aircraft weights above 30 tonnes = Base Rate + Weight Rate x 5 x Square root of (MCTOW – 5)

» where the Minimum Price, Base Rate and Weight Rate are provided by the relevant price table.
Price tables provide the prices for each service and location. Price tables are provided in Airways’
standard terms and conditions
» where MCTOW is an aircraft’s maximum certified take-off weight measured in tonnes.

There are also different formulas for aerodrome services, en-route domestic, and en-route oceanic service.
More information can be found at the New Zealand Service and Pricing Framework page.
1. Yes I know that New Zealand is not a country in Europe.


Is overall pressure ratio same as compressor pressure ratio for a gas turbine engine?

Modern turbofan engines typically have several stages of compression, the overall pressure ratio is the ratio of the highest pressure to the intake pressure. But the pressure ratios of each compressor can be a different.

The fan and booster add a bit of compression, followed by an optional intermediate pressure compressor and finally the high pressure compressor.

Because of these multiple shafts and therefor having some parts of the compressors not working on their design point you probably won't get accurate results by simulating a single stage compressor.


When ATC uses distances, are they using nautical miles or statute miles?

ATC uses nautical miles, this is because it's the ICAO standard documented in Annex 5 - Units of Measurement to be used in Air and Ground Operations, which states that Nautical Miles are to be used for distance and Knots for speed as an alternative non-SI measurement. Kilometers are actually the primary distance measurement because they are the SI standard, however nautical miles are so entrenched they've kept them and there's no termination date.

The ICAO annex is hard to find because everyone wants you to buy it, however the standards have been copied into this CAAS document word for word if you want some light bedtime reading.


Remember, radials come from a fix.  You cannot hold south of a VOR on the 360 radial in the same way that you could not hold east on a 270 radial using the VOR as the holding fix.
You could hold south on a 360 radial, but the fix would have to be somewhere away from the VOR.  For example, if you're told to hold south of the 10DME on the 360 radial, that could be done.
What that would mean is that your fix, for the purposes of the inbound course, would be the 360 radial of the VOR at the 10 DME distance.  So your racetrack pattern would be south of the point 10 miles north of the VOR (per the compass rose's north).
Examples:


Is $24.01 million for 15 used A320 reasonable?

Short Answer: If the 24 Million was for just 15 airworthy A320s, then yes, its a steal because $24 Million is barely enough to buy 2 or 3 A320 engines. However, Niki Airline likely has hundreds of Millions of dollars in debt that British Airways is also "buying", that is why the final price seems so low.

Longer Answer:
There is so much that goes into the value of an aircraft that this cannot be definitively answered. Even a properly maintained aircraft may be of little value if it has too many cycles (landings and take-offs) and total hours. For example, if those 15 A320s all need engine overhauls then its going to cost a lot more than $24 Million to get those done, not to mention the downtime.

Additionally, and adding even more uncertainty to your question (sorry), is that the $24M was for the airline. As you probably know, the airline includes other assets, such as the landing rights that you mentioned, but it also includes other liabilities, such as debts to previous creditors (i.e. vendors, debt service, etc).

So, just as a simple illustration, lets say that the 15 A320 are collectively worth 150M and the landing rights are worth 200M for a total combined value of $ 350M, if the company has liabilities (debts) of 300M, then the net value would be 50M for the whole company, and paying 24M would be a steal!  But on the other hand if the company had liabilities of 400M then the company would be worth -50M. Usually, when a company is insolvent it is in this situation where it may have some valuable assets, but it has more liabilities than the assets or cash flow it generates. British Airways is likely hoping to streamline the business and turn it around, or just scrap it and take the landing rights for its own fleet.


What is the US FAA concerned about when it comes to psychiatric medications?

The FAA is concerned that individuals taking anti-depressant medication will not have the mental focus required when juggling multiple tasks in real time in the cockpit.

anti-depressant medications are psychotropic -- They are specifically intended to alter the takers' mental state.  The assumption is that any artificial modification of mental state will negatively impact aeronautical decision making.

The SSRI special issuance protocol requires, among other things, the applicant to demonstrate the ability to quickly and accurately perform multiple tasks simultaneously.  The idea is to make sure that you aren't being slowed down by the medications to the point where you can't make the right decisions rapidly enough to ensure safety of flight.


Do financiers request IDERA's for small aircraft?

Firstly just a little bit of background. IDERA's - Irrevocable Deregistration and Export Request Authorizations - are issued under the Cape Town Convention (or Cape Town Treaty). This is a voluntary convention that countries can subscribe to. It essentially provides more assurance for financiers, who can therefore provide lower interest rates to aircraft buyers.

The FAA states the eligibility requirements  for IDERA's, which, for fixed-wing aircraft, need to be able to carry at least 8 people, or can carry goods in excess of 2750 kilograms (6050 pounds). So most aircraft considered 'small' probably would not be covered.


What airplane does this vintage instrument panel come from?

The shape makes it clear that this is from a single seater or tandem aircraft. This makes a glider very likely, which is supported by the "Vario" engraving over the column of small holes on the bottom right.

A little googling then brings me to this page and the assumption that this panel is from a Schempp-Hirth Standard Cirrus, Serial No. 176. The plane was badly damaged at Minisink, NY on October 23, 1976 in a botched landing and consequently written off. At that time it was registered as N11JY.

Schempp-Hirth Standard Cirrus (picture source)

Standard Cirrus instrument panel (picture source)


What is the optimum speed for takeoff flaps?

I assume the question means optimum climb speed.

From the Boeing 737 NG FCTM (3.30 Takeoff and Initial Climb):

  V2 + 20 is the optimum climb speed with takeoff flaps. It results in the maximum
  altitude gain in the shortest distance from takeoff. Acceleration to higher speeds
  reduces the altitude gain. If airspeed exceeds V2 + 20 during the initial climb, stop
  the acceleration but do not attempt to reduce airspeed to V2 + 20. Any speed
  between V2 + 15 and V2 + 25 knots results in approximately the same takeoff
  profile. Crosscheck indicated airspeed for proper initial climb speed.


What concerns do the FAA and EASA have in 2014 with "own-ship position display" on EFBs?

Display of ownship's position has a very strong effect on the mental model that the pilot has of it's navigation. When the EFB displayed position is wrong, the change that the pilot will detect that by comparing to other instruments or outside visual are very limited. This is a safety concern.

To have the EFB approved to display ownship's position, the most straightforward way would have been to certify it under TSO C129a "Airborne Supplemental Navigation Equipment using the Global Positioning System (GPS)" TSO-C129a has now been superseded by TSO-C196 which has slightly different requirements.

Often class I or class II EFB will have a GPS receiver that technically could be used as the source of ownship's position. The GPS receivers chips used in are not designed and certified against the "Minimum Operational Performance Standards for Airborne Supplemental Navigation Equipment Using Global Positioning System (GPS)” (RTCA document DO-208), which is a requirement of TSO-C129a or "Minimum Operational Performance Standards for Global Positioning System/Aircraft Base Augmentation System" (RTCA document DO-316) which is a requirement for TSO-C196.

The major technical difference between simple commercially available GPS chips and aviation grade GPS chips is that the latter include a Receiver Autonomous Integrity Monitoring (RAIM) function which does Fault Detection (and Exclusion).

If a GPS satellite would drift out of it's orbit or GPS data gets corrupted in the receiver, an ordinary GPS chip would most likely display a position error, while an aviation GPS chip would either indicate a failure state (fault detection) or still display the correct position (fault exclusion). This protects the pilot from being mislead by a map shift.


Why do commercial pilots always engage reverse thrust even if it is not necessary?

The correct answer is, habit patterns.

If your habit, as a pilot, is to ALWAYS select reverse thrust, you'll do so reliably even when the weather is bad, you're fighting gusty crosswinds, and there is whatever else going on. On the other hand, if you sometimes do & sometimes don't select reverse thrust, that habit pattern isn't there to back you up when you have the proverbial "dark & stormy night" and getting into reverse thrust right away may be the difference between staying on the runway or running off the end.

For example, if I'm landing a fairly light aircraft on a 12,000' dry runway in DEN with a little headwind, it is entirely possible to leave the thrust reversers stowed, roll out with the speed brakes deployed, tap the brakes slightly, and exit on the last high speed taxiway at a normal taxi speed.  And I'd burn less fuel and make less noise doing that.  But at my carrier, I'm not allowed to, because it's considered that the habit pattern of always deploying the T/R is so important that it's worth it to burn that extra gas even when it isn't strictly necessary, so that on the day when it's vital, the habit pattern to grab the T/R's right after touchdown is strong.

I don't think that this is an OpSpec (i.e. FAA) requirement, at least for the aircraft that I fly, but I'm quite certain that it is a requirement in our books, so my supposition is that it's a company requirement.  If that assumption is correct, then other companies might choose to do differently (and I recall one early morning arrival into Frankfort on a Lufthansa A-320 that used NO reverse thrust, but some heavy braking instead -- presumably to reduce noise at that hour of the morning).  The fact that safety is so important, though, probably drives plenty of operators to make the same choice that our carrier does: build the habit of ALWAYS using reverse thrust -- even though that means sometimes using it when it isn't necessary.


Is it harder to learn to fly rotary wing after learning on fixed?

Rotary flying is much harder than fixed wing to learn, however learning after you get a fixed wing license is easier in some ways because you already know:

Radio procedures
How to set up and use instruments
Navigation and flight in controlled airspace
Air law and regulations
The "gestalt" of flying

This means all you need to do is learn to fly the helicopter, which is tricky because helicopters are much less stable than fixed wing airplanes. If you take your hands off the controls of fixed wing airplane it will generally stay pointed where you put it, especially if it's trimmed properly. If you take your hands off of a helicopter's controls in hover things will go very, very badly in a real hurry so you have to be making constant control inputs. The controls of a helicopter are also very sensitive, it is a very different (and more challenging) type of flying.


Do biplanes need bigger tail volume coefficients than monoplanes?

Tail volume is a measure for the ability of the tail to compensate for the destabilizing pitch moment created by the wing in case of the horizontal tail and for adverse yaw in case of the vertical tail. This pitch moment is proportional to the square of the wing chord (one factor comes from the area, the second from the lever arm), so if you compare two otherwise equal designs, one of which is a biplane and the other a monoplane of twice the chord, the dimensionful horizontal tail volume (expressed as tail surface times tail lever arm) of that monoplane needs to be twice that of the biplane. To counter adverse yaw, however, the dimensionful vertical tail volume is the same.

Tail volume is normally made dimensionless by referencing it to the wing area and the mean aerodynamic chord (for the horizontal) or wing span (for the vertical tail). Since the area of both designs is the same and the MAC of the monoplane twice as large as that of the biplane, both dimensionless horizontal and vertical tail volumes become equal even though the dimensionful horizontal tail volume of the monoplane is twice as large.

However, if you compare wings of the same aspect ratio (which might be a better basis), both the chord and the wing span of the monoplane are larger by a factor of √2 but there is only one wing to consider versus two in case of the biplane. Now the dimensionful horizontal and vertical tail volumes for the monoplane are larger by a factor of √2.

Only when you make the chord of both wings equal (doubling the span of the monoplane in the process) will the dimensionful horizontal tail volume of both designs be equal but now the vertical tail volume needs to be twice as large.

Wing stagger with the same incidence on both wings would move the biplane closer to the monoplane with twice the chord whereas a lower incidence on the rear wing would indeed create that reflex effect and reduce the instability of the wing. Still, you need control power to change angle of attack quickly enough for maneuvering, so I would be careful with any further reduction of tail volume even if the staggered biplane wing by itself is stable already.


Have there been any 'proper' field trials of Automated Air Traffic Control?

No

Short answer, but there has never been anything resembling a "proper" trial. There have been a few small scale, limited and tightly controlled trials, but nothing over any significant time frame, involving a significant number of aircraft, or even involving aircraft in "normal" use.


Blackburn T.5 Ripon

The Blackburn T.5 Ripon was a British carrier-based torpedo bomber and reconnaissance biplane which first flew in 1926. It was used by the Fleet Air Arm as a torpedo bomber from 1930 until 1935. Ripons were also sold to Finland, where they continued to be used in action in the Winter War and the Continuation War until 1944.

(Source: iwm.org.uk) The exact one, number 4 on the side.

A Blackburn Ripon Mk.IIA torpedo bomber of No 811 Squadron touches down on the flight deck of the fleet aircraft carrier HMS FURIOUS.


Does angle of rotation during takeoff affect the g-force?

The increase in g-force in a banked turn is due to centrifugal force. That's a completely different situation than the g-forces during takeoff.

The forces during take off will be due to acceleration from thrust and, at rotation, an upward acceleration due to lift (and part of the thrust). The pitch angle doesn't have a direct relationship to g-force as the roll angle has in a banked turn. During climb the pitch angle can be as high as 15°, but once you've established a steady climb and a steady airspeed the g-forces are just the 1g of gravity.


Writing Research: What stick sensation would you expect in an Su-15 with a total hydraulic flight system failure?

Su-15 (as well as all Sukhoi interceptors since Su-7) had a completely irreversible control system with no manual override. This means, 100% of torque was produced by hydraulic boosters, and the force on the control stick was simulated with a special variable spring loading mechanism.
So, a theoretical total hydraulic failure would result in loss of control, while the stick would move 'normally' - just without any effect.
Su-15 had 4 hydraulic systems, with 2 of them used for flight control. The most anticipated reason for dual failure would be loss of the engines; for that, there was an electric pump in one of the systems. In case of control problems, the pilot would check and ensure that the emergency pump was on. This pump provided only a limited amount of control (and for a limited time).
Now I'll have to challenge the premise a bit. First, Su-15 was an interceptor, and low-altitude flight (even training) would be quite unusual for it (though not impossible). Its lowest altitude of intercept was 2 km, and the main emphasis was on intercepting higher altitude targets. Its radar was unable to track targets on the earth surface background. It was not meant for terrain following, so even if it was flying at a low altitude, it would be fairly clear of immediate obstacles. Which gives the pilot at least a few seconds to react.
Second, the pilot would, of course, eject. Even though in emergency situations (esp. unanticipated emergencies) people do all sorts of things, pilots, and esp. pilots of aircraft with irreversible control, know that loss of control = eject. It's pointless to 'fight' with the stick. However, as I said, in all likelihood there would be a few seconds to think. In most situations (like the engines failure) you won't have an immediate loss of control: the failure is fairly gradual. This would see the pilot trying to ascertain what was happening. Difficulties with control at low altitudes often require reducing the airspeed.1 But a catastrophic sudden loss of control is a clear signal to eject.

1 By the way, early Su-15 had pitch control problems at transonic speeds at low altitude due to insufficient booster torque. It felt like no response (or poor response) at higher G manoeuvres. This things could be resolved by reducing speed.


Barometric altimeter data during high vertical g-forces?

In the formula $dP = -\rho gdz$, $g$ is the local gravitational field that is pulling on the fluid (the atmosphere).  The apparent value of $g$ within the airplane is not relevant.

So other than making sure the sensor itself isn't affected by changes in apparent weight, there's no need to correct for accelerations of the barometer.

  And yes I am intending to ask whether the sensors are designed such that their “apparent weight” (or more generally their mass acted on by any directed force) is not an appreciable factor in their reported measurements?

My understanding is that no, it's not.  Altimeters already have a measurement error at level flight, and they have a lag when altitude is changing.  Additional errors due to apparent weight would have to exceed those to be worrisome.

"vertical acceleration" is rather small for almost everything that's not a military fighter.  But a plane could easily pull 3g's in a level turn, and you would want your altimeter to remain accurate.

Obviously it's possible to design an instrument that is more susceptible to such inaccuracy (such as have the pressure vessel balance against a weight to indicate the altitude), but that shouldn't be a problem for a normal instrument.

The aneroids in a diaphragm barometer can be oriented so that downward forces have no effect on the reading.  Also, the smaller and lighter the disks, the less that any acceleration will affect the reading.

I found lots of articles on various corrections for barometric altimeter readings based on temperature and different atmospheric profiles, but none on g-load corrections.  That suggests to me that no correction is necessary for standard instruments.  Perhaps someone can find published performance data for an installed instrument that calls it out explicitly.  The lack of information I found appears reasonable, but not completely satisfying.


Yellow chevron markings at end of runway, what do they mean?

Those are not chevrons but arrowheads used to mark the start of the runway. So, yes, he did land on the taxiway.

Source: FAA Airfield Standards Quick Reference

He does land slightly before the runway threshold. He even says he is going to land short. Since there was nothing on the taxiway leading to the runway then it seems there is no problem doing that.

screenshot from Google maps of KYKM runway 22 threshold

For comparison, chevrons mark either stopways or blast pads and look like this:

same source as first image

They may include an EMAS bed, so touching down there would not be a good idea.


Do any aircraft have a "self-contained ILS"?

Approaches guided by GPS are called RNAV; it can provide both lateral and vertical guidance, in some cases to the same precision as ILS Cat I, without need for a radar altimeter--which is not standard equipment. (There are also non-GPS ways of using RNAV, which are mainly used by older airliners that haven't been upgraded yet.)

Note that standard GPS has accuracy of 100m; SBAS (aka WAAS) gets that down to 7.6m.  Both are standard in aviation GPS units these days, and GBAS (aka LAAS) will eventually get that down even further.

There are already three times as many RNAV approaches as there are ILS approaches with more appearing every day, and most aircraft are now equipped to use them or probably will be soon. IOW, the essence of what you propose is already here.

Instrument approaches do have to be pre-planned to ensure obstacle and terrain clearance, so airplanes can generally only use them to land at airports. (The rules are different for rotorcraft, and that's generally what you'd use for rescue, but I'll have to leave the specifics to someone else.)

Many large aircraft carry weather radar, but it's too heavy for light aircraft; both can use satellite weather data services, in addition to getting weather updates via radio the traditional way.


Can an S-duct fit a turbofan exhaust instead of the intake?

Yes they can, and it has been done in the Garrett AiResearch ATF3. Although the engine was not hugely successful, it is still being used in aircraft today.

From this answer:

  The hot exhaust stream is deflected back into the fan bypass, which cools it down and results in a low IR signature. This engine is used in the Dassault Falcon.

You can see several S-ducts leading the hot exhaust gases internally into the little staircase-like contraptions behind the fan.


How much does it cost to design a jetliner's wing?

This is what I could find, but perhaps there are other methods as well.

A 2002 MIT research[1] arrived at a correlation between weight and cost based on publicly available figures. The non-recurring (development) cost of a wing is broken down into:

engineering
manufacture engineering (ME)
tool design
tool fabrication
support

The engineering of a wing (clean slate) costs \$7,093 per pound. The total for the wing is \$17,731 (per pound). If it is not a clean slate design, say the DC-10 / MD-11 example, then it's 20% of the engineering, 5% of the tool design/fabrication, and 50% of the ME and support.
Applying to MD-11 and MD-90
The heaviest (OEW) MD-11 weighs 291,120 lb. With the wing 23% of that based on the research, and accounting for inflation (from the year 2000), the total development cost would have been $783 million (in 1987) for the wing if MDC had went with a new design.
MDC spent less than that for the whole "engineering, tools and flight testing," a cool \$700 million. Plus "$2.5 billion in inventory for initial production." (latimes.com, 1990)
Based on this method, the value is $328 million (in 1996 dollars) to redesign the MD-90 wing (full value, not just engineering).

Engineering
ME
Tool Design
Tool Fab
Support
Totals

40.0%
10.0%
10.5%
34.8%
4.7%
100.0%

Wing
\$7,093
\$1,773
\$1,862
\$6,171
\$833
\$17,731

Empennage
\$20,862
\$5,216
\$5,476
\$18,150
\$2,451
\$52,156

Fuselage
\$12,837
\$3,209
\$3,370
\$11,169
\$1,508
\$32,093

Landing Gear
\$999
\$250
\$262
\$869
\$117
\$2,499

Installed Engines
\$3,477
\$869
\$913
\$3,025
\$408
\$8,691

Systems
\$13,723
\$3,431
\$3,602
\$11,939
\$1,612
\$34,307

Payloads
\$4,305
\$1,076
\$1,130
\$3,746
\$506
\$10,763

Seeing how the table above shows how expensive the empennage and systems are, and with the major changes done to those areas on the MD-11, one can see why they went this way.
(Regarding a comment about the weight of composites vs. metals: a composite airliner is generally not lighter.)

1: Markish, Jacob. Valuation techniques for commercial aircraft program design. Diss. Massachusetts Institute of Technology, 2002.


Are military jets always scrambled when communication to a commercial aircraft is lost?

Over Europe and many other parts of the world, the general rule is that if an aircraft in controlled airspace does not reply to instructions from Air Traffic Control, military jets will be scrambled to intercept the aircraft.

Basically you are asking if there are exceptions to that rule.

I think there are a few. First of all, ATC will not inform the military of every instruction that is not reacted to; there wouldn't be enough jets. Pilots do miss instructions occasionally, sometimes aircraft are handed of to the wrong frequency by ATC, wrong frequencies are entered into the radio etc. All these things usually sort themselves out in matter of minutes and it would be a waste of resources to scramble. If no contact is established after a certain amount of time, only then the military will be involved. However if an aircraft starts to deviate from earlier acknowledged instructions without reacting on the radio, it is safe to assume that the time to alert the military is considerably shorter.

And then of course the aircraft must be in range of military jets. An aircraft halfway across the Atlantic is simply too far out for most interceptors so until the aircraft is getting closer to shore I don't think there is much reason to scramble jets.

Some more information about loss of communications, causes and prevention  can be found in this Skybrary briefing note. For obvious reasons the exact procedures for scrambling military aircraft are not publicly available.


Do airline pilots practice stalls in actual aircraft?

In 727 and 747-100/200 aircraft and their simulators for the two airlines I flew those aircraft for up to my retirement in 1999, all stall training was done in simulators, never in the actual aircraft.

Stall training in the sim consisted of slowing (or otherwise loading up the wing) until the stick shaker started. Recovery was accomplished by unloading the wing and then adding power in that order. Whether unloading the wing was accomplished by just relaxing back pressure or by positive forward movement of the control column (or by rolling out of a bank if you were in one) was a judgement call.

Typically the sim instructor wanted a significant stick shaker warning, not just a quick blip that you immediately stopped. Also, it was considered bad form if, once you stopped the stick shaker, it started again. Obviously that meant you had loaded up the wing again and were moving toward a secondary stall, which was a definite no-no. As I remember, that was more likely to happen if you made the mistake of leading with power rather than first reducing the angle of attack.

Every once in awhile someone would want to play a bit and see how the sim reacted to a full stall. As I remember, the sim would just bounce around with a very high sink rate. I never felt its response to a full stall was at all representative of what the actual airplane would do.

I experienced the stick shaker in flight in a 747 three times that I remember: once during a test flight in which that was part of the testing, once with a check airman who liked to play, and once on the line.

The instance on the line was when I was still an f.o., and it was the captain's leg. He had extended the speed brakes for the descent. When he brought the power up for the final approach, he forgot about the speed brakes. The stick shaker came on immediately. He realized what he had done, and retracted them, and the stick shaker stopped.


What is the aerodynamic benefit of trailing edge sweep?

Both leading and trailing edge sweep help to reduce compressibility effects. For simple estimates, quarter chord sweep is used. This is more influenced by the leading edge, but the trailing edge is still involved with 25% of the total value.

If we look at the particular influence of trailing edge sweep, it is mostly found in the effectiveness of flaps and ailerons. Their effectiveness is proportional to the cosine of hinge line sweep. However, flaps at the end of a long wing chord will create a high pitching moment, requiring a big tail. Most delta wings use simpler, less effective flaps with less moment change.
In supersonic aircraft trailing edge sweep helps to reduce sonic boom intensity.

In the end, trailing edge sweep is mostly an outcome of the design process, similar to wing chord. The structural engineer will want to have a deep root airfoil in order to have enough wing height for a stiff spar or the landing gear without increasing relative thickness too much, and the aerodynamicist wants to reduce wetted area, since it will create friction drag and increase wing mass. In the end, all have to agree to a compromise.


What is the difference between a P-51 Mustang and an A-36 Apache?

They were largely the same aircraft but the first line of the A-36 wiki sums it up nicely

  the ground-attack/dive bomber version of the North American P-51
  Mustang, from which it could be distinguished by the presence of
  rectangular, slatted dive brakes above and below the wings

later in the article they go on to list some more features

  The contract for 500 A-36A aircraft fitted with bomb racks, dive
  brakes, and heavier-duty wing, was signed by Kelsey on 16 April
  1942,[6] even before the first flight of the first production P-51 in
  May 1942.

This website also lists the same mods as well as some other fun facts.

This website lists two other features noteably the vent window which is not mentioned elsewhere.

  ...and the installation of small vent windows in the windscreen side
  panels. In addition, two Browning M2 .50 caliber machine guns were
  mounted in each wing, and two more .50 cal. guns were mounted in the
  lower nose to fire through the propeller.


How do flaps deploy and stow with very large wing flex?

If the flap is on 3 tracks, it flexes with the wing and there is compliance built into track system.  If the flap is on two tracks, it'll stay straight as the wing in front of it curves.  But in a two track system, the panel is short enough that the wing curvature is negligible to the flap.

What that statement means is that with a 3 track panel, as the flap flexes with the wing, the total distance between the 3 tracks gets longer and shorter by some value, say an eighth or quarter of an inch or whatever.   To accommodate this the center track is used to control the lateral position of the panel, while the inner and outer track has lateral side play built in to the roller system so the change in distance doesn't cause binding in the outer tracks.

Slat systems are the same. The center track has guide rollers that locate the slat and the outer ones are "floating" laterally by having larger roller clearances.  Other panels on the wings like spoilers that are much shorter are able to get away with just using spherical bearings that allow some compliance as everything moves.


Does an airline have to pay if fighters intercept one of its aircraft?

Probably not very likely. In 1978 Soviet Union asked US\$100,000 (\$375,200 today) for "caretaking passengers" after their interceptors forced to land KAL 902 on the frozen lake (has never been paid). However firing the two R-60 missiles from interceptors into the airliner was for free.


What is the optimal sequence of departures and arrivals on a single runway?

Usually a mixed usage runway is more efficient than a dedicated arrival runway(s). Arrivals are harder to get closer together than departures as well. Running a final with 5 mile gaps(for wake and all departures) is a good way to do dep-arr-dep-arr.

With dedicated Dep-Arr runways, and assuming you have aircraft ready to go, your expected hourly rate for Arrival only runways is usually around 30, whereas with a departure only runway the rate is about 45 or so(assuming minimal spacing, and have decent fan headings, and the departure routes are split decently to allow good separation heading to the center).


Is there an engine thrust level limit for deploying thrust reversers?

Engines must be at idle thrust to enter reverse thrust.  This may not be 100% true of the physical action of engine entering reverse thrust (opening the buckets or translating the cowling), but it is required by the thrust levers.  In all airplanes I'm familiar with the thrust levers must be at idle to enter the reverse regime,  In the EMB-145 the reversage was below idle (i.e. you keep moving the levers aft) through a gate.  Even if the engine is capable of entering reverse thrust not at idle, there is no way to command it without first being at idle.


What can I do to save my life if oxygen masks fail to drop down? Is it possible?

If you are asking about all or some of the masks as your title suggests, it has happened before.

One such example from 2008 is Qantas Flight 30.

  After the accident, numerous passengers said that some oxygen masks did not deploy, whilst others had deteriorated elastic. Consequently, it was reported that one passenger smashed a panel of the ceiling to attempt to gain access to the masks. It was stated that these passengers were deprived of oxygen until the plane was lowered to a breathable altitude.

Best thing to do is to stay clam, and to breathe slowly/normally (deep calm breaths).

Worst case scenario if a person is a smoker and obese, they'll pass out but will regain consciousness when the pilots reach a lower altitude. In a rapid depressurization emergency, the pilots act quickly to descend, it will be a matter of few minutes until the air would have sufficient oxygen again.

Pilots have different mask systems that should be tested routinely.

Related:

How long will one remain conscious in the event of a sudden cabin depressurization?
Is it possible to suffer barotrauma during decompression?


Would shutting down the engine have prevented the Atlantic Southeast Airlines Flight 2311 crash?

The description of the accident says the propeller went to a flat pitch of 3°, which is still positive. At such angle, the air is trying to spin the propeller in the same direction as the engine, so the engine running helps the propeller spin. Only if the propeller went all the way to negative pitch would the engine be the air trying to spin it in opposite direction and therefore produce additional drag, but it appears that propeller was not built to allow negative pitch.

So I don't think it would have helped. It probably wouldn't have made much difference in the very flat pitch.


Which is more efficient: a jet engine or a rocket-powered engine?

Jet engines are far more efficient. The metric to compare them is 'Thrust-specific fuel consumption', i.e. the amount of fuel used to produce one unit of thrust. Fuel consumption per distance traveled is proportional to this.

A few figures from that page:

Rocket engine: Space Shuttle main engine, 225 g/kN.s

Jet engine in afterburner: EJ-200: 48 g/kN.s

Jet engine, dry: CF-6: 17 g/kN.s

So a rocket uses ~10 times as much fuel to produce the same thrust. Even if you add afterburning, a jet is more efficient.

During and after World War 2, there was some interest in rocket-engined aircraft. The Me-163 saw service in the Luftwaffe.

The interest continued for a decade or so, until jet engines with afterburners were developed. One exponent of that interest was the Saunders-Roe SR-53, a short-range interceptor with both a jet engine and a rocket.

It was developed in response to an RAF requirement for an aircraft that could take off and get to high altitudes very quickly; more quickly than could be attained with the jet engines of the day.

Jet: Armstrong Siddeley Viper, 1640 lb thrust.
Rocket: De Havilland Spectre, 8000 lb thrust.

Fuel carried:
jet: 500 lbs
rocket: 10,500 lbs

Endurance:
jet: 45 minutes
rocket: up to 7 minutes

speed:
jet: 180 kts
rocket: accelerate to Mach 2 once, then the fuel ran out

(source: mostly 'British experimental jet aircraft', Barrie Hygate.)

It was superseded by the EE. Lightning, which had 2 afterburning jets. It had 4 times the range despite carrying less fuel and more payload.


Can the phrases "carbon fibre reinforced polymer composites" (CFRP) and "carbon fibre-epoxy composites" be used interchangeably?

No.
Epoxy resin is more specific than the terms polymer or plastic from CFRP. CFRP does also include carbon fibre composites with other duroplastic matrix materials (e.g. phenolic resin) or even thermoplastic matrices.


These are antennae for the IFF (Identification Friend or Foe) system.  IFF is a system to help distinguish friendly aircraft from unfriendly ones.

This particular antenna arrangement is used on only a couple of F-16 models. The first was the F-16 Air Defense Fighter (ADF) version. This model was converted from the F-16 Block 15 for use as a fighter interceptor for the US Air National Guard. A total of 271 F-16A and F-16B aircraft were upgraded to this standard between 1989 and 1992. One of the modifications made during the conversion process was installation of the Teledyne/E Systems Mk.XII Advanced IFF system, given the designation APX-109. This system included four antennas, often nicknamed "bird slicers," placed in front of the cockpit canopy with additional antennas on the bottom of the inlet.

From: http://www.aerospaceweb.org/question/planes/q0286b.shtml


Are there cases of aircraft moved off runway by pushing them with vehicles?

Pushback trucks are called that for a reason, they push aircraft :)

They could be used to push or pull a stuck airliner like you mention, IF the muck isn't so bad they themselves get stuck trying that is. Most AFAIK aren't exactly designed for off road operations.


What are the aerodynamic advantages and disadvantages of the Weltensegler wing?

The inspiration for the Weltensegler wing were birds. The reason for their wing shape is structural, however, not aerodynamic. Your photo shows the 1922 version, called "Baden-Baden Stolz", which was a follow-on to the original and more ambitious version of 1921. The 3-side-view below shows the planform (picture source). However, this airplane never flew, which probably saved the life of its pilot. While pitch and limited roll control was possible with the elevons on the outer wings, no consideration was given to directional control.

The 1921 version was controlled by warping of the outer wings, the washout of which was controlled with pulleys and springs. The idea was that this would help to adjust the wing shape to flight speed. The picture below shows the first and last flight, which is historically significant as the first glider flight in which a considerable gain in height was achieved. However, it ended in a spiral dive which killed its pilot (picture source).

Weltensegler is actually the name of the company which was founded by Friedrich Wenk. Alexander Lippisch was one of his employees.

The configuration cannot be recommended for a glider. It is much better to have a straight inner wing and dihedraled outer wings, as explained in this answer. The anhedral of the outer wings of the Weltensegler wings will produce a downforce on the windward wing, rolling it into the wind which is the opposite of what is needed for coordinated flight. Other configurations using an "M"-shaped wing did so for different reasons and use rudders and much more anhedral on the outer wing panels.


Can a low flying jet fighter lift water?

The visual effect in the picture you found seems to suck water out of the sea, in this real footage the f-18 air shockwave tends to push water down, and makes a trail.


What are the bump outs on a Bell 430 helicopter for?

They are called sponsons and act as enclosures for the retractable main landing gear.  The 430's ancestor, the Bell 222, was equipped with the same fairings.


Why would an artificial horizon's roll axis be different on ground and in flight?

The problem
As already pointed out in some of the comments, this is a structural problem of using an IMU-only AHRS unit. This unit cannot distinguish between acceleration due to centrifugal force, and acceleration of the earth.
For example imagine that you fly level, and then roll into a coordinated turn. The short-term roll-rotation will be picked up by the gyroscope, however in the coordinated turn itself the AHRS only "sees" a constant acceleration through its local z-axis (because you are in a coordinated turn). The gyroscopes on the other hand, will not see any movement at all. Therefore the filter will (over time) assume level flight. In essence, you cannot distinguish between gravitational forces and centrifugal forces in forward flight with the accelerometer alone.
Ways to solve this problem
I am aware of two ways of fixing this problem:

Buy a good gyroscope: If you buy a very good gyroscope, you can simply use its measurements and completly omit the accelerometer. However even good MEMS Gyroscopes still have considerable drift (typically you will notice an roll-angle drift after a couple of minutes). If you are willing to spend your life savings (I belive the price tag is 250k$) on a Ring Laser Gyroscope, you can also solve your problem. Fun fact: A couple of flat earthers bough one of these devices and ultimatively measured the earths rotation...

If you are on a Budget however, it may be cheaper (and more reliable) to give your algorithm some sort of velocity feedback. Typically, this is either a GPS unit (which not only produce a measurement of position, but also a velocity measurement), or a velocity measurement based on a pitot tube. With this measurement available, the centrifugal force can be calculated and be accounted for.

Implementation
How can you implement this in software? Well either you take existing projects from any of the common flight controllers like Ardupilot, or betaflight and adapt these to your needs (not knowing your hardware, I cannot tell you how labor-intensive this will be). Or you try to program your own estimation unit based on your IMU and velocity sensor. Before you try to figure out everything by yourself, I would recommend to first take a look at existing Software, which already implements everything necessary. In a nutshell, you just have to program a relatively simple Kalman filter based on the known equations of motion of a 6-DoF point which also estimates the gyro offsets. A very good example of how such a filter is designed can be found on the PX4 project (yet another flight control stack), which details how their Kalman filter is built up. One (open access paper) detailing such an implementation can be found here. I would regard this as the state of the art, and how one would commonly address this problem. The block diagram is displayed here:

Another implementation hinging on a simpler complementary filter, is described in this paper. Based on some minor assumptions it removes the centrifugal force via the airspeed, and uses the centrifugal-force-free acceleration as an input to a complementary filter. Although the used IMU is very high quality, and no algorithm for bias and drift compensation is used, you might get this to work with some adjustments. The block diagram is quite compact:

Disclaimer: I have no affiliation nor contact with any of the authors of the aforementioned papers. I do not own any of the images displayed here, these are directly taken from the papers.
P.S.: Interestingly enough, I also came across this link which offers some bounty for an open-source software implementation of such an AHRS unit.


How is windspeed scaled in wind-tunnel tests?

In order to achieve the same flow conditions, you need to match several similarity numbers. The most important one expresses the ratio of inertial forces to viscous forces within a fluid and is called Reynolds number (Re):

$$\text{Re} = \frac{v\cdot l\cdot\rho}{\mu}$$
Nomenclature:
$\kern4mm v\kern6mm$flow speed
$\kern4mm l\kern7mm$characteristic length along flow path, like wing chord
$\kern4mm \rho\kern6mm$fluid density
$\kern4mm \mu\kern6mm$dynamic viscosity of the fluid

The next one on the list is the ratio between flow speed and the speed of sound in the fluid and is called Mach number (Ma):
$$\text{Ma} = \frac{v}{a}$$
Nomenclature:
$\kern4mm a\kern6mm$speed of sound
Others depend on the nature of the flow - if oscillating vortex shedding is involved, the Strouhal number needs also be observed, with elastic oscillations the Froude number or with heat transfer the Prandtl number.

In your case of a 1:10 model, the flow speed needs to be increased tenfold in order to match the Reynolds number. However, this will bring you in conflict with the Mach number, because the faster flow will probably already be supersonic. This problem is discussed at length in this and the linked answer, however, knowledge of the influence of flow speed is implicitly presumed.

Normally, in a wind tunnel test the flow speed is too low for correct scaling (which means that the viscous forces are higher in proportion to the inertial forces), and the consequences of this mismatch need to be covered by correction factors.

There is no need to scale forces correctly. Wintunnel models were hung on wires which were connected to scales to measure forces and now are mounted on a sting, the bending of which is captured by strain gages or an internal balance. Only the models used in free-fall tunnels for spin research will create as much lift as they weigh. The forces measured are used to compute coefficients, dimensionless numbers which are normalized for speed and size. When multiplied with the speed and size of the original, the (corrected) coefficients will yield the actual forces and moments.


Why does the Information Manual say "C172S - Flaps 10 (Preferred) for Normal Takeoff", when the models before S-model do not have this note?

The Cessna 172S has more power (180hp vs 160hp for 172R) and higher MTOW
(2550lb vs 2400lb for 172R).
This means that folks used to rotating at 55 knots IAS in earlier models would be closer to stall if taking off "clean".  Another way of doing it would be to add 5 knots and rotate clean at 60 knots.
Vx is also a bit higher in the 172S at 62 knots IAS.
Vy is at 74 knots and Vbg is still at 65 knots, indicating few changes aerodynamicly, just a bit more weight requiring more airspeed to generate adequate lift, or flaps can be added to increase lift coefficient at a lower airspeed.


How does the mounting location of a jet engine affect aircraft performance?

Engine location performance-affecting factors:

1. Mounted in the wing root

low asymetric yaw on engine failure, less rudder required: less drag
no engine pods: less parasitic drag
engines closer to CG, less downforce needed from the tail:  less drag
very little reverse thrust available
Little space for high-bypass-ratio engines

2. Mounted in pods under the wing

high asymetric yaw on engine failure requires larger rudder: drag penalties
engines provide bending relief on the wing, allowing better wing design (thinner wings): less drag
at high incidence angles the pods can prevent spanwise flow: less drag and better stall characteristics
full thrust can impose a large, undesirable, pitch up moment (think stall recovery)
less freedom in roll on cross-wind landings
Location ahead of the wing's elastic line helps to dampen flutter

3. Mounted inside the tail or on pods on the rear fuselage

low asymetric yaw on engine failure, less rudder required: less drag
wing design is freed from the need to accomodate engines, allows for more complex wing designs: better performance throughout the flight envelope
heavy engines so far aft of the fuselage require wings mounted further aft, and a higher tail to support that: more drag
Lower landing gear required, especially in case of short fuselages

That's about what I can come up from memory, maybe someone can merge all answers into a comunity wiki kinda post..


How does jet training work for private pilots? Are there jet trainers?

There is no FAA requirement for any specific pilot certificate level beyond Private to get a type rating in any jet. In fact, many owner/operators of small business jets (CJ, 500s, Phenom, etc) only have a Private certificates.

See 14 CFR 61.31

The only FAA requirements are that you have a Private certificate with multiengine and instrument ratings. Additionally, a High Altitude Endorsement is required to take the actual type checkride unless you meet the grandfather requirements of the HAE. RVSM is NOT required to take the checkride, but it is required before flight into or through RVSM airspace.

You can enroll in a simulator based Part 142 course (think Flight Safety, Simcom, LOFT) and complete your entire training in a Level C or D full flight simulator, but once you complete your training you will have an SOE limitation on your type rating. This is per 14 CFR 61.64. This regulation says you must have 25 hours of Supervised Operational Experience in the aircraft before you can act as PIC in that aircraft unless you meet specific requirements including total time, time in multi-engine turbine (including turboprop) aircraft, military training, etc.

You can enroll in a part 61 course and complete your training in the actual aircraft and once you pass the type rating, you would not have the SOE limitation under 14 CFR 61.64 since you took the actual checkride in the aircraft as opposed to an FFS.

You can enroll in a Part 142 initial hybrid program that offers simulator training for the first part and when you have complete the sim portionof your training they move you to the aircraft for the final training segments and checkride. This also eliminates the 61.64 limitiation on your certificate.

Three things to remember: First, ALL type ratings are done to ATP standards regardless of certificate level and Second, SOE or not, insurance companies rule on how much time you will need to fly with a mentor pilot before going out on your own and finally an in-aircraft checkride for your type rating will be far easier than an in in-sim checkride.


Who has authority over stadium TFR exceptions in VFR flight?

The answer will vary based on the location - San Francisco, Los Angeles, and New York may each have different arrangements. However, in general, it'll come down to how the different ATC facilities have the situation worked out with each other.

The stadium TFR itself does not help much. The relevant section states that:

  THE RESTRICTIONS DESCRIBED ABOVE DO NOT APPLY TO THOSE AIRCRAFT AUTHORIZED BY AND IN CONTACT WITH ATC FOR OPERATIONAL OR SAFETY OF FLIGHT PURPOSES

Any of those facilities could provide the authorization - so it's then down to which will do so. The answer to that will depend on the structure of how the facilities work with each other. The ATC facilities will have Letters of Agreement which state that a given area of airspace is managed by a given facility, as well as how handoffs are handled.

The facility that can provide flight following is also the facility that can authorize you into the TFR in that area. To figure that out, all you have to do is ask: call up Norcal Approach or Oakland Tower, and ask for flight following. If they can do that, then they're the right folks to ask about transiting the TFR. If not, they'll give you another frequency to try. Of course, just because they have authority over the airspace doesn't mean they'll grant the request.


Airline flight scheduling method differences

There are many academic papers available for general airline scheduling topics. Airline flight schedule planning is a huge topic, existing within the more general field of Operations Research. The models and algorithms used are not simple by any means, and thus there could exist many kinds of differences between the methods used by each of the different airlines.

Considering such models are part of how airlines gain a competitive advantage, specific airline methods, at least for now, are proprietary information.  Perhaps this will not always be the case, but it would take a change in the  way the airline industry operates for this type of information to be publicly available.

That being said, the data about the output of those models are freely available, collected by the U.S. Government (see the Bureau of Transportation Statistics).

Theoretically, one could mine the available data to reverse-engineer some differences, but these will be theories at best.


Is the life of pets considered when dealing with a cargo fire indication?

What happens to live animals in cargo depends on the type of airplane and the class of cargo compartment they're traveling in. For a typical passenger airliner, if you check your animal as baggage, they're going into the "lower lobe cargo compartment" under the cabin floor. This is classified as a Class C compartment, which essentially means that the crew have no access to it in flight, so it must contain fire detection and extinguishing systems. The applicable regulation is 14 CFR 25.857.

Quite simply, there are no considerations for live animals in Class C compartments. If you look in Boeing cargo fire checklists (copyrighted so can't post here, but you might get lucky with Google), the steps in the checklist deal with discharging the Halon into the cargo compartment and adjusting the pressurization system to minimize flow into the cargo compartment. This helps maintain the minimum required Halon concentration to provide the first big knockdown blast to stop the fire from spreading, and then maintain a low-level concentration to keep it suppressed for the length of the diversion to a landing. Unfortunately, that means any live animals will suffocate since Halon displaces oxygen.

For dedicated freighters such as the 747-400F/747-8F/777F etc., the main deck area is considered a Class E cargo compartment, which doesn't have a fire extinguishing system. If a fire is detected here, the procedure is to depressurize the entire cabin and minimize/cutoff air flow to the main deck area, and climb/descend to a mid-altitude (somewhere in the 24,000-28,000' range depending on the airplane) to minimize oxygen and help suppress the fire. If animals are transported here, rather than the Class C lower lobe compartments, they may survive. They may become hypoxic and lose consciousness, but there's no Halon to suffocate them. Depending on the length of time for the diversion to safe landing site, the lack of oxygen may be a serious issue for some animals just as it can be for humans, but that's a guess as I'm not a vet.

Bottom line is if you're taking your pet with you on a commercial flight, the safest, most comfortable, and least traumatic place for them is with you as a carry-on item.


Why aren't there any jets with horizontal-stabilizer-mounted engines?

There are two configurations I can think of.
1. The jet mounted on the horizontal stabilizer (above, below, or the tip)
Unlike the vertical stabilizer, the horizontal stabilizer is trimmable (THS). It's constantly moving, which means when it moves, so would the thrust line. A kind of thrust vectoring that you don't want. For example, trimming for slow flight during approach, the thrust line will point down and aft of the CG, which will in turn point the nose further up, this is a kind of a destabilizer. Even if the angle is not too big, the changing thrust line will always act against the intended trim. And lastly with the engine constantly on the move, the blade tip clearances will need be bigger, which will in turn reduce the engine's efficiency.
The required strength issues that result in a heavier weight are also a factor. This also impacts the loading flexibility; a tail heavy plane will reach a point where you can't put as many passengers in the back without adding a forward ballast.
2. The jet mounted at the root and doesn't move with the THS
While certainly achievable, like the L-1011's number two engine wrt the vertical stabilizer, the issue here is not why aren't the jet engines there, it's why the THS is not there.
The horizontal stabilizer of a plane like the DC-9 (and its extended family) is purposefully placed above the tail, creating a T-tail. With the tail swept back, the top of it is farther from the plane's center of gravity, giving the THS a bigger moment arm, and in turn allowing a smaller THS, and the other benefit that comes out of that is the end-plate effect of the T-tail, which also permits a shorter fin for the same control authority.
You'll also notice buried engines are of the older small-diameter type, except for large planes like the L-1011, but still that makes maintenance access a lot harder, than an exposed engine.


The only reason for your flight to operate at such low altitude is because it is cheaper for them to do so.

As you said it is due to weather, other route/altitude may not be available. They can cancel the flight but that is likely to be costly. They may have to find accomodation for you and crew until they can put you to the next flight. Sub-optimal flight maybe better than no flight in this case.
They may need that aircraft at that location the next day. If they choose to cancel your flight today, they will have to find a way to have this aircraft or another aircraft to fill in for the required flight the next day. They might as well fly a slightly more expensive flight at lower altitude rather than fly an empty plane to Boston.
It is possible for them to wait for weather to improve but there is an issue of crew working hour. A pilot cannot work more than 8 hours in a day without provision for additional crew. They may approach that limit and the wait for weather to improve might means the airline has to provide another crew for the flight and might mess up crew schedule for the next few days.

So for the airline, in this case, flying lower and slower maybe a better option for them. Hence higher fuel comsumption is better than no flight.


Do airline companies have a Chief Medical Officer?

I'm not sure if every airline is the same. However each major airline I am familiar with does have a medical unit, usually headed by a doctor.

However, most of their efforts are actually dedicated internally - by that I mean looking after their employees. Things like:

Assessing the employees ability to return to work after an injury or illness
Fatigue management policy
Assessing whether a certain condition is acceptable to work with
Overseeing drug and alcohol rehabilitation (in some cases in Australia at least the employee is not automatically fired for being drunk/on drugs, they are allowed to complete a program and continue work)
Occupational health and safety assessments
General 'doctoring' duties for aircrew

Of course they are also involved in passenger health policy development, but as I said - the majority of their work is dealing with their own staff (at least, this is from my viewpoint, but I may not be seeing the whole picture).

In terms of an outbreak like you have mentioned, there is always an action plan ready to be put in place which is developed with the government health department (or CDC in USA).


On SEP airplanes, why does the fuel consumption decreases with temperature, pressure and airspeed being equal?

In the examples cited, there is a slight increase in Density Altitude (DENALT), which results in a slightly higher TAS.  As the air becomes thinner, fewer molecules pass by the aircraft per mile, resulting in a lightly less loss due to drag.  Increased temperature does not have the same range of change as altitude, however, it is nonetheless a higher DENALT, which is thinner air.

As an aside, in practice, you will note that the throttle becomes wider open with less dense air, until it is fully open. (Note that RPM is not the primary measure of power, rather fuel burn is. RPMs will become higher at higher DENALT for the same power.) At that point there will be no more available power, and any increase in temperature or altitude cannot be compensated for by increasing the throttle setting.

You will also note that less energy is expended per mile at higher DENALT, not factoring in the cost of a climb to that altitude.

Finally, a different practical example of this: When flying in icing conditions, conditions (and the POH) may call for continuous carburetor heat at altitude. When this is done, the engine should be releaned, as the DENALT will be higher, and if uncompensated for, will result in a rich mixture which could foul spark plugs.


Would turbulence created by two jumbos less than 100ft apart cause both of them to crash?

The probability of two jets surviving such a close encounter are extremely remote.

Setting aside the fact that it is difficult to imagine two aircraft flying in the same altitude in opposite directions (commercial aircraft are separated by 3 miles laterally and 1000 ft. vertically) ,if the scenario unfolds as in the movie and the horizontal separation between the aircraft on approach is as shown, the pilots would not have time to react and take the necessary evasive actions.

Assuming that the jets are cruising towards each other at 900 kmph, the combined speed is around 1800 kmph, or half a kilometer per second.

If the TCAS is not working and the aircraft come within five km (the distance in the video is considerably lower, less than a km) of each other, the pilots have less than 10 seconds to get out of each other's way.

The civil aircrafts are not designed for such rapid roll rates. The inertia of the aircraft (especially the 747) will limit it.

Another thing to note is that the modern flight control systems will not allow airline pilots to carry the maneuvers shown in the flight. The pilot can override the Flight control Computer.However,in this case, they would not have time to react.

If by some miracle the aircrafts cross each other, they will fly right into the other aircraft's wake turbulence, which will have disastrous consequences, especially for the smaller aircraft.

Sources: airpower.maxwell.af

In case of small aircraft flying behind a heavy jet, FAA regulations require a minimum separation of 5 miles, lesser than which the effect of the wake turbulence (wingtip vortices) can have serious consequences.

Source: Aeronautical Information Manual

FAA conducted a test on the effects of wake turbulence by flying a 737 behind a 727, which shows the loss of control associated with flying in the wake of another aircraft.

Once (if) the aircraft pass each other, they should be brought to level flight as quickly as possible (whether it is possible or not is another question) to prevent stall. In this critical juncture, if the aircraft wings encounter wake turbulence, the control of the aircraft will be loss, resulting in stall.

Finally, in case two aircraft do approach each other in the same altitude in opposite directions, there are laid down procedures to follow. None of them involve the stunt shown in the movie.

When two aircraft are flying head on, each must move to their right.

Source: planefinder.net

If two aircraft are at the same height and on converging courses, the aircraft with the other on its starboard side has to give way.

Source: planefinder.net


Are there any airliners not made by Airbus or Boeing?

Yes. Ignoring companies that used to exist but are now bankrupt/merged into Airbus or Boeing, you have companies from countries that aren't historically too friendly with the US and Western Europe. For instance, Tupolev makes the Tu-204, which is currently in production and seats over 175 passengers. The Ilyushin-designed Il-96 is a widebody in current use some places (Russia, Cuba). Before the Cold War ended, Russia had more indigenous airliners; Aeroflot now largely uses Boeings and Airbuses, but there are still Russian aircraft that see use.

In addition, you have newer manufacturers starting to enter the market: Bombardier with their CSeries, Comac (in China) with their C919 (in development), and Irkut with their MC-21 (in development). Embraer makes planes of more than 100 seats (although they're shorter-range, and you might consider them regional jets).


How would fighter jets make contact with a previously hijacked aircraft?

Nothing. There is no possible world in which someone has the necessary training, knowledge, and experience to operate the complex communication equipment, yet doesn't know 121.5.


How does an aircraft maintain an orientation that was actually caused by a external disturbance?

Stability of the aircraft has nothing to do with control surfaces or moving CG to control the aircraft (that kind of aircrafts are very rare anyways). When researching or testing for aircraft's stability, control surfaces are either fixed to neutral position or they let alone to float freely, so control surfaces are not used to make aircraft more stable. That's of course true for conventional aircraft.
On the other hand you can produce an unstable or neutrally stable aircraft, however in that case you are required by regulations and nature to use some kind of control computers to keep aircraft in control all the time. MD-11 and Boeing 777 are two examples of this. Even though they are not unstable nor neutrally stable, they are definitely less stable than the requirements for the conventional aircrafts. To get away with that they have to have couple of flight control computers to keep the aircraft sane. However, even when the automation fails these aircrafts still have some positive static stability. How far you can go towards unstable side depends on design choices. You can further read Peter's post about why there is really less bang for buck when you further decrease the stability.
When statically stabil aircrafts are disturbed by any outside or inside forces (gusts, hitting control column etc) it  creates a restoring moment which returns aircraft to its initial position. That makes aircraft easier to fly.  Unstable aircrafts however tends continue to move in the direction of disturbance. So if a gust hits the aircraft and increases the AOA slightly, the aircraft continues to increase its AOA by itself and snap out of control eventually. That’s why you need flight control computers to stop any uncommanded movements.
The picture you show illustrates a neutrally stable aircraft, which means that it does not show any reaction to disturbances and maintains its disturbed position. Some aircrafts are designed that way to increase its maneuverability, reduce trim drag and increase fuel efficiency. Check out that link for a comparison of stable and unstable fighter aircrafts and how they behave during maneuvers. Some of these aircrafts are dubbed under different names such as relaxed static stability instead of calling them unstable or neutrally stable aircrafts in order not to freak out the masses.
Stability of aircraft is very closely related with CG position. As a general rule moving CG forward makes it more stable and moving aft makes it less stable and eventually unstable if gone out side of CG limits. Normally you won’t intentionally move CG out of limits but there are accidents which caused that. For example in this Boeing 747 accident at Bagram, payload got loose and moved aft of the aircraft uncontrollably during takeoff and aircraft become extremely unstable that no control input would be able to recover it.
These all are static stability. The dynamic one is another beast.


Can supersonic conditions be replicated on the ground?

Yes, supersonic conditions can indeed be replicated on the ground for purposes of airframe and engine testing.
Arnold Engineering Development Complex (AEDC)
The U.S. Air Force and NASA both operate supersonic wind tunnels, as do Lockheed, P&W, and others. The most advanced of these facilities are probably those at Arnold Engineering Development Complex on Arnold Air Force Base. I won't mention any specific numbers from memory because they've likely changed since I worked there and I can't remember exactly which ones were classified/FOUO/otherwise-not-public, but let's just say they're pretty good.
AEDC has test cells designed both for testing jet engines as well as for testing scale models of airframes (or full scale airframes if it's a small enough airframe, such as a missile.) Additionally, it has facilities for testing upper-stage rocket motors. Lower-stage rocket motors don't need the facilities at Arnold, as those are designed to operate in the atmosphere and can just be lit up out in a desert somewhere.
According to Wikipedia (which I believe is sourced from publically-available information,) Hypervelocity Wind Tunnel 9 can generate air flow of Mach 14 with simulated altitudes from sea level to 173,000 ft.

AEDC Tunnel 9 (with test article)  Source: Wikipedia
In case that's not enough, G Range can fire projectiles at roughly the speed of low Earth orbit. However, this one is kind of stretching the definition of "supersonic," since it's typically pumped down to such negligible air pressure that Mach number isn't really defined before a shot at that kind of velocity. Still, as the wiki article indicates, it's capable of shots at up to 1.7 atmospheres, so it definitely counts as legitimately supersonic on those shots.

AEDC Range G  Source: Wikipedia
Holloman Air Force Base
In addition to wind tunnels and other facilities at AEDC, the U.S. Air Force also occasionally uses rocket sleds, such as the one at Holloman Air Force Base, which currently holds the speed record for any type of non-air/space vehicle at 6,416 mph / 10,326 km/h (Mach 8.5.)

Holloman High Speed Test Track Source: Wikipedia

Land Speed Record Rocket Sled at Holloman Source: Wikipedia

The "Speed Limit" at Holloman Air Force Base
Source: some guy's website, which got them from publically-released images from Holloman AFB


How did Wilbur Wright create and use the formulas he mentions in his letter to Octave Chanute?

I do not have first-hand knowledge of this formula, so what I write below is speculation. But the Wrights used sound physical reasoning, and I will try do do the same.

Power in physics is the product of force and speed. The formula does indeed contain a force (thrust) and a speed (pitch times rotation speed) if the terms used by Wilbur are interpreted in a certain way. Pitch today is an angle, but I would think Wilbur meant with pitch what is termed distance D in the picture below.

Propeller advance ratio (picture source)

This is consistent with his earlier sentence where he gives a length for the term pitch. The term pitch * RPM/60 is actually the flight speed in m/s.

Now to the term 5/6: I would expect that Wilbur calculated the pitch from the incidence of his propeller. Since the propeller blade needs some angle of attack to produce thrust, the actual distance traveled through air is a little smaller than what Wilbur got. Therefore, I think the term 5/6 accounts for that slippage and had been determined empirically.

Now for the revolutionary increase in efficiency: I do not know what engines Wilbur used for comparison, but the low number he cites suggests that he used exceptionally poor specimens .


Transition level has to be readback and what about transition altitude? is it also required to be readback by the pilot?

The word “level” is used to refer to Flight Level (or Pressure Altitude). It can (and probably is in this case) also infer the word Altitude (or True Altitude). They are sometimes used interchangeably. Though, by strict definition, they are not the same.

In the US, QNH (Transition Altitude), QNE (Transition Level), and QFE (Transition Height) are not widely used much outside of the military. Instead, the term Lowest Usable Flight Level is substituted. The word “Transition” itself is commonly used to refer to passage through an area. The process to transition the Transition Layer between the Transition Altitude and the Transition Level is standardized for all flights and airspaces.

The Flight Level is the altitude standardized at an altimeter barometric pressure setting of 29.92 inches of mercury. That allows all aircraft to fly at a standardized altimeter adjustment. In theory, this should avoid confusion caused by aircraft flying at different Indicated Altitudes but the same actual True Altitude due to different Kollsman Window settings. All aircraft in the US are to adjust their altimeters and fly using Flight Levels at and above 18,000 feet MSL. Above this Flight Level, precise Absolute Altitude is not necessary.

The following was taken from the FAA-H-8083-16B, Instrument Procedures Handbook, 2017 (IPH)


Can I apply for a Gold Seal any time, or only when I renew my CFI certificate?

You can apply now. It will be reissued every time you renew your certificate.

http://www.pilotratings.com/goldseal.html


Is there a source of information on the Aerodynamics of Non Rotating Round Disc Wings?

Yes.

The first published results of measurements made by O. Flachsbart of the AVA Göttingen on a flat disk can be found in the collection Ergebnisse IV (PDF!). He reported on a hysteresis in the angle of attack range between 39° and 42°, where the wing is either stalled or not, depending from which side this angle of attack range is approached.

Lift and pitching moment coefficients of a flat disk, page 97 of Ergebnisse IV

When C. H. Zimmerman tested disk-shaped wings with an Clark Y airfoil section in the early 1930s in the NACA 7 x 10 ft wind tunnel, he called them circular airfoils. The results of this testing can be found in NACA Technical Note 539 (PDF!) from August 1935.

Figures 10 and 11 from the last page of NACA TN 539

Sighard Hörner collected the little data available on circular wings in his book Fluid Dynamic Drag (page 17-8) and concluded:

  Disregarding any dreams of "flying saucers", the athletic implement
  called discus seems to be the only practical application of a circular
  planform.

However, Zimmerman went on to inspire the Vought V-173, the "flying pancake" of 1942, from which the Vought XF5U was developed.

Vought V-173 in flight (picture source)


How would a tricycle-geared aircraft be recovered from a tip-up?

While I do not have a specific source to cite, which is always important to reference in regard to any aircraft work, I'm basing this answer on my training as an FAA certified aircraft mechanic.  (There are many more experienced mechanics than myself out there, but alas, none who have done this particular process have arrived yet.)

In general, if you have to work on something that does not already have specified methods from the aircraft manufacturer, the go-to reference is:

  AC43.13 1b/2b - Acceptable Methods, Techniques, & Practices of Aircraft Inspection and Repair

But I don't know if that volume covers this mishap.

I can tell you with some certainty that several inspections will be called for on that aircraft.  The skin and structure of the empennage, of course, but also the main gear will almost certainly require a "hard landing check", since the airframe was adversely loaded so much that the nose lifted.

There's every chance that the event will call for a "tail strike" check, which can be extensive.

If the aircraft were tipped forward in an uncontrolled fashion, the nose gear may come down quite hard, but the fact that the forces involved would be unknown (compared, say, to a landing touchdown at a known sink rate and aircraft weight,) would also necessitate a hard-landing inspection of the nose gear.

In a hard-landing event, the fuselage structure may also be compromised, and relevant areas are also checked, as prescribed by the aircraft's particular inspection and maintenance documents.

When an airframe ever does something in an uncontrolled fashion, many inspections will be needed to conservatively account for every possible imagined consequence, and that can cost a great deal of time and money.

All this is preamble to the kind of approach a good mechanic will take to a problem that offers little previous experience.  Every A&P can change a tire, balance a control surface, and check for corrosion, but getting an aircraft back on all wheels safely is not often addressed.

We know a few things:
• The nose gear can support the unloaded nose of the plane (and we know from records what weight range that is).
• Dramatic movements are frowned upon.
• The aircraft was fine before that last load was introduced.
• Personnel safety is a primary concern. (No dangerous heroics!)

Things we don't know:
• How hard you can pull down on the nose gear before damaging something (they were not meant for such loads!)
• Whether the main gear are at or over their load limit already.  (If people were watching the aircraft's weight and balance figures, we wouldn't be in this mess.)
• Whether the fuselage/empennage has been structurally compromised.
• How fast/hard the nose might come down with the weight distribution corrected - too fast?

From these things, we can determine what NOT to do:
• Pile a bunch of baggage handlers in the nose until it tips back down.  Yay, concussions!
• Adding weight (ballast) in general. (Will the airframe be damaged further?)
• Haul downward on the nose with a winch. (Don't tear the nose gear off!)
• Jack up the tail from the rear. (We don't know if it will hold.  Probably, but we don't take chances.)

Variables that could be leveraged:
• Can the cargo be winched back towards the front without endangering anyone?
• Does this model ("type") have fore and aft fuel tanks in the main fuselage, and if so, can fuel be moved between them (or pumped out) for weight shift, in safety?

We're left with two primary goals:
• Decrease the weight moment behind the mains in a controlled fashion, hopefully without adding any weight to the airframe.
• Do not let the nose fall uncontrolled.

My approach would resemble the following, depending on equipment available (or that could be found in the local region):

Provide safe support under the nose of the aircraft that can support the normal full weight of the nose of the aircraft.  We want to ensure the nose cannot come down without our say-so.  A sling is ideal, and the airframe manufacturer will have specifications on how to lift and support the airframe.

In a comment, @TomMcW provided a nice linked visual in this YouTube video:

As seen in the video, the best option would be an overhead crane, with a sling approved for lifting that airframe wrapped under the forward fuselage.

Here's a more extreme example of using a sling to lift an aircraft:

Once the aircraft is in a stable support with minimized risk of unexpected movement, the next phase is to UNweight the rear, in the safest way we can.  That might be to pump out fuel from an aft tank, or winch a cargo container slowly forward, or (the least favorite) manually unload items, using as few personnel as possible.

As weight is removed from the rear, the airframe will weigh down the sling.  You can lower the sling in a slow and controlled way, with the main gear "chocked".

Once the nose is down, sorting out the rest of the cargo and fuel will be trivial, as flight crew can enter and operate internal systems.

But one thing I know for sure: that bird ain't flying today!


Does anyone have photos of internal parts of ELAC, FAC, SEC or Boeing 777 flight computers?

This is an indirect answer at best, but I think you'll get something good out of it.

I would definitely recommend you have look at CuriousMarc's series on YouTube where he and a couple other SMEs restore an original Apollo Guidance Computer to working order. You might think "that's not civil aviation, why?", but the AGC was the first digital fly-by-wire system. It was revolutionary both in terms of it's use of silicon integrated circuits and it's effects on software engineering. the AGC was also the basis for the first fly-by-wire systems installed on aircraft for atmospheric flight.

The other reason I'd recommend this is because it has all of the electrical cutting and shutting that you seem to be expecting. They spend a lot of time looking over original schematics and performing diagnostics with Marc's extensive personal collection of equipment in order to find individual failed circuits which require repair. They also had to find ways to interface the computer and emulate missing components, which involved a lot of bespoke design.

I'll be honest, I think there is a possibility you might find modern computers quite boring in comparison if your interest is limited to the circuits and does not include the software (not easy to tell from the wording of the question). This is for two reasons:

The AGC represents a time where the atomic components of the digital computer could still be seen with the eyes and cut/soldered out by hand. That is almost certainly not the case with modern computers, and I would also expect that the vast majority of people who work with the aircraft directly have never cracked open one of the computers for this reason. They are sealed (maybe even tamper-proofed), and are simply replaced as a unit and shipped back to the OEM when any invasive work is required.
A cursory search informed me that the original A320 computers actually used derivatives of the Intel 8086. If you're interested in early x86 micro-architecture (especially in fault-tolerant configurations), this is interesting. But, if you're expecting to open the computer and find the flight control laws to be implemented in hardware, you'll be a bit disappointed.


How does the position of vortex generators on engine cowlings affect flight?

The vortex generator helps only at high angle of attack by energizing the airflow between nacelle and wing. During cruise it will create additional drag without much benefit, especially if the nacelle-wing-combination has been designed well.

However, in the landing configuration it can help to lower minimum airspeed by several knots and make shorter landings possible. Now the aircraft maker has to decide what is worth more: Shorter field length, or slightly less cruise drag.

The Boeing 737 started life with a much more slender engine and had a very short landing gear when more fuel-efficient engines came to market. A lot of brain- and computing-power was needed to develop its pear-shaped engine nacelles, and the vortex generator became an essential element of it. At the inside location it helps to keep the flow path between wing, fuselage and nacelle clear of separated air, whereas on the outside a second generator would make only a minor difference.


will a Sears-Haack body straighten itself out if "launched" sideways?

will an object moving at high speed find and stay in its most aerodynamic orientation?

No. It will most likely tumble around. With the center of gravity behind its center of pressure, a body of rotation is inherently unstable.

  if not, will a major control surface like fins make it do so?

Yes. That is the reason for those large surfaces at the rear end of airplanes.

This answer is about directional stability over Mach. At supersonic speed directional stability drops with increasing Mach number.

This answer covers a similar topic; now it is about the proper location of fins at supersonic speed.


Why is a 737 Original speed-restricted below 10 kft with inoperative windscreen heating?

To reduce damage in case of a bird strike.
The restriction is not only for the 737-100 and -200 models, the 737 NG QRH says:

WINDOW HEAT OFF
In flight:
WINDOWS HEAT switch (affected window) ..... OFF
Limit airspeed to 250 knots maximum below 10,000 feet.
Pull both WINDSHIELD AIR controls. This vents conditioned air to the inside of the windshield for defogging.

The reason for restricting the speed is that the windows are less elastic at lower temperatures and can therefore not absorb a bird strike as well as at nominal temperature. Since most bird strikes occur below 10,000 feet, the restriction only applies there.
I could not find a good source for this, but it is e.g. discussed on pprune.org:

Window heat also ensures the screen vinyl layer is kept elastic and resilient and better to absorb damage in case of a bird strike - not so if the screen is cold and hard.

and airliners.net:

cold windows become very brittle whereas warm windows have a degree of elasticity in them that makes them withstand birdstrikes better.

A new window was developed for the 737 and is installed on all models built since mid-September 2010. The technical data by PPG Aerospace list the following among the improvements:

Elasticity at low temperatures reduces potential for delamination and cold chipping

So low temperature elasticity seems to be improved. I do not know, if they removed the restriction from the QRH for the newer models.
Airbus also does not seem to have such a restriction. From pprune.org:

When I asked Airbus exactly this question their reply was that the windscreens had been tested at 350+ knots and cold.....therefore no problem!