What protocol should be followed after accidentally entering restricted airspace with a UAV?

Well this one I can answer even without being an expert on India's airspace regulations: Entering a "no-fly zone" or other restricted area with an aircraft - even an unmanned one - is going to be some kind of a violation.
You local authorities could tell you what kind, but it doesn't matter: it's a situation to be entirely avoided.

You should plan your test flights to occur far, far away from such restricted areas (as well as from airports, population centers, "open-air gatherings of people" (to use the FAA's parlance), or anything else that you might disturb, damage, destroy, or annoy during your testing.
This is almost certainly what the DGCA is going to tell you if you contact them and ask for advice on test parameters for an Unmanned Aerial Vehicle, but more importantly it's just plain good old fashioned Common Sense!

If you cannot exercise such common sense you should rethink & rework your plans until you can.
If after real, honest rethinking you're still in a situation where you feel you may inadvertently penetrate controlled or restricted airspace then coordinate with the agencies that handle that airspace PRIOR TO YOUR TESTING to make appropriate arrangements.

Now if you exercised all due common sense and still the absolute worst happens (Murphy's law rears its ugly head and LITERALLY everything that can go wrong does - even the engine cutoff and the emergency self-destruct didn't work!) you may still accidentally wander into airspace you shouldn't be in.

If that DOES happen your procedures should be effectively the same as they are in a manned aircraft anywhere in the world if you encounter the same situation: Communicate, Confess, and Comply.
Contact the controlling authority (e.g. tower, approach, the military division responsible, etc.), let them know what's happened, tell them where you are (in this case, where your drone is - they'll likely ask you to copy a number if they want to find out where "home base" is), and comply with any instructions they give you.
(This may mean you need a radio and a list of frequencies on the ground with you - picking up a sectional chart would be a good idea. You may also need a radio-relay in your UAV depending on what kind of range the vehicle has...)

Yes, the controller might get a little snippy with you (you are after all somewhere you're not supposed to be. Controllers tend to not like that!), and you might get in a little trouble for the violation (because again, you're somewhere you're not supposed to be), but that's all preferable to the potential alternative of smacking your UAV into a plane full of people at 300 feet on short final to Indira Gandhi International Airport.
As with all aviation operations, safety must be your overriding concern.


What is a GDS (in the context of the airline industry)?

GDS stands for Global Distribution System:

  A Global Distribution System (GDS) is a network operated by a company
  that enables automated transactions between travel service providers
  (mainly airlines, hotels and car rental companies) and travel
  agencies. Travel agencies traditionally relied on GDS for services,
  products & rates in order to provision travel-related services to the
  end consumers. A GDS can link services, rates and bookings
  consolidating products and services across all three travel sectors:
  i.e., airline reservations, hotel reservations, car rentals.

These are the databases that maintain travel reservations and allow travel agents to see available inventory and book tickets. As noted in the Wikipedia article, they may also host airlines' computer reservations systems and passenger service systems. For example, Amadeus operates a system used by hundreds of airlines, not to mention thousands of hotels, rental car companies, tour operators, and other travel businesses to maintain reservations and track inventory, and a global distribution system used by tens of thousands of travel agencies, ranging from storefronts to online booking websites, that allows agents to book travel with these providers.


Can you change airways when they cross without a named fix?

Yes one can fly one airway to intercept another. Many reasons exist as to why not all intersecting airways have an intersection, the simplest being, it wasn't necessary.
I will suspect one may encounter difficulties in executing your desire to change airways as stated. Such would be the inability to file a flight plan with dispatch or that flight planning software can't/won't accept this unconventional navigation method and the most illogical, if one could accomplish the later, I would image would be ATC. Why? Because the controller has never encountered this situation, before and doesn't want to explain their actions should something go afoul.
For years ATC would issue preferential routes to aircraft departing KPIA to KORD as such; PIA PIA030R V10 PLANO ORD. Aircraft would depart KPIA on the tower assigned departure heading then be vectored to join the PIA 030-radial to intercept Victor-10 northeast of BDF VOR onward to KORD. Then computers became more involved along with flight management systems and pilots were no longer capable to navigate this route because computers couldn't calculate the routing or how to intercept one radial (airway) from another without a set point (intersection) along the second radial , something pilots had done since the 1950's.


How precisely must ATC speed instructions be adhered to?

You don't say what country, but I'll base this on the U.S... There is no "rule" here, however you can expected to be held to the Airmen Certification Standards. These standards are used by your designated pilot examiner (DPE) to determine if you are able to perform according to published standards.

For example, the Commercial Pilot ACS, depending on what phase of flight you are in, says that you should be able to maintain a specific speed +/- 5 knots. A lot of places in the ACS say "maintain manufacturers recommended speed".

So the FAA expects you to be able to reasonably maintain an assigned speed given that you were provided your license in accordance with ACS. That being said, if ATC assigns you a speed (N1234 Maintain 200kts until established), you should be OK if you are doing 190kts, or 210kts, but if you are blowing through there at 250kts, ATC will chime in and ask you to slow down.


What kind of liquid can be seen 'leaking' from the upper surface of the wing of a Boeing 737-800?

The pictures show water condensation on the wing upper surface due to very cold fuel in main tank number 2.

The fuel is cold because the air temperature at cruise altitude is significantly colder than the air temperature encountered during the descent.

The condensation appears to be oozing from the wing but it is in fact flowing slowly over the surface, filling and overflowing every seam and imperfection.

Since you have provided photos and not a movie, I can't tell you what the "pulsating" really was, but it probably was either a slight boundary layer turbulence, or changes in the seam geometry due to wing flexing.

EDIT: There seems to be some confusion regarding the "pulsating" nature of the observed flow, with at least one correspondent1 insisting that the uneven flow proves that the fluid originates from inside the wing.

There are many mechanisms that could account for a pulsing or uneven flow of fluid over the wing, without resorting to the theory of a bleeding airplane.

The most likely reason depends on the fact that the wing surface is not a single sheet of metal, but contains discontinuous pieces such as spoilers, flaps, access panels, ailerons, etc. Because the wing flexes, the volumes of the spaces between these pieces, and the voids under some of them, continually change in flight.

Water flowing over the wing will fill some of these spaces and voids. Once a void is full, changes in volume will alternately squeeze out some water and suck some in. This could certainly look like a pulsating leak to someone who has not seen it before.

Another effect that can lead to pulsating does not require changing volume, but just a trough formed by the butting of two panels, roughly perpendicular to the airflow, filled by the trickling condensation. The air does not always flow smoothly over the wing2, and minor turbulence can press down on one section of the trough, causing water to spurt out of another section.

Seconds later the turbulent flow shifts, and the water hurries along the seam to pulsate in a different place.

The question can be completely resolved only by someone who can consider these theories while observing the effect.

The original poster, actually.
In spite of the large arrows painted on the wing surface.


Can a US registered motorglider be flown in Canadian airspace when piloted by a pilot with the appropriate FAA glider license?

Unless your license says on its face that it doesn't meet ICAO requirements (as FAA student, sport and recreational licenses do), then when you are flying an aircraft registered in that same ICAO member state, that state's licensing rules apply and all other states must accept it as valid regardless of their own rules.

So, in your example, if the FAA says your aircraft is a "glider" and you have a private glider license, then you're legal in Canada even if, for instance, Transport Canada thinks your aircraft is an "airplane" and would require an airplane license for their own pilots to fly it.


Would the benign spiral maneuver be one alternative to dealing with being "stuck above" or inside a cloud?

It works in most gliders because they tend to be neutrally stable in roll and - the big one - have speed limiting spoilers/dive brakes.  I'm not sure it's safe to do that in an older glider without speed limiting spoilers.

In any case, most power planes, once disturbed beyond the ability of dihedral effect to restore level flight, will naturally descend in an ever steepening spiral without pilot input.  There aren't any ways to limit the speed on a GA power plane (gear and flaps won't cut it) the way spoilers/dive brakes on a glider can.  It would need a speed brake that can hold the plane to below Vne in a vertical dive.


What twinjet with rear-mounted engines and swept wings did I see in Savannah, GA?

Gulfstream G500. The G600 is longer. The angle is close, but look at the window just ahead of the wing fairing. The original is faint but clearly ahead of the fairing curve. The G600 window is in the middle of the curve. The G600 has a bigger wing.

G500 pinterest

G600 wikipedia


It sounds very much what you're experiencing is a Phugoid cycle

Image License info
To put simply, your aircraft is not trimmed correctly. As it descends slightly it gains speed, which increases lift over the wing making it climb. This has the effect of it losing some speed, reducing the lift over the wing causing a descent, increasing the speed - and on it goes.
Full scale aircraft from light to airliner can and do experience the same thing. One notable case which comes to mind is the accident sequence of United Airlines 232 which lost all hydraulic pressure and thus had no control surfaces operational. They were controlling pitch (and roll) somewhat using engine power only, and thus did not have exact control of pitch and experienced significant Phugoid cycles.
Side note: You're unlikely to be experiencing ground effect at treetop height unless you have very tiny trees or very large wings.

When an aircraft flies at a ground level approximately at or below the half length of the aircraft's wingspan there occurs, depending on airfoil and aircraft design, an often noticeable ground effect
source


Is a propeller with two long blades more efficient than one with three shorter blades?

As Troy E and Dave said, most of this question is already answered here.

In addition to this previous answer, just remember that a propeller is a technological solution to a simple question: how do we make the aircraft fly ? Therefore, there is no single solution, but multiple compromises that can be found depending on various parameters, mostly based on the type of operations the aircraft should take part in :

Speed
Altitude
Mass of the aircraft
FOD / injestion risks and tolerance
...

Since your question only states the efficiency of the propeller, you actually miss at least part of the real problem.
Let's say you manage to make a propeller with an efficiency of 1, but that it weighs 1 ton or is impossible to manufacture, you won't get far.

In that sense, only considering the efficiency to say what is the best solution is not good enough. The best solution is the best compromise between all of your requirements, that's why it is so difficult to find ;) !


Is it illegal to partially block the aisle on a passenger airliner?

Cargo cannot block the aisle -
FAR Part 121.285, governing U.S. Air Carrier Operations, states in pertinent part:
FAR 121.285-
(emphasis mine)

(c) Cargo may be carried aft of a bulkhead or divider in any passenger compartment provided the cargo is restrained to the load factors in §25.561(b)(3) and is loaded as follows:
(4) Its location does not restrict access to or use of any required emergency or regular exit, or of the aisle in the passenger compartment.


Why are oxygen requirements based on pressure altitude?

The air in the lungs is in pressure equilibrium with the cabin, but not temperature equilibrium. It's always at body temperature. So the only variable that can affect how much oxygen is available to the body is the pressure of the outside air - thus pressure altitude, not density altitude, is physiologically relevant.

That said, if the density altitude is high it may mean you are hot and dehydrated, and the deleterious effects of those factors may be additive with those of hypoxia.


What is this aircraft from "Devil Girl From Mars" (1954)?

It's a Vickers VC.1 Viking in the livery of British European Airways (BEA).

(By RuthAS (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons)


If a pilot waves back, does it violate the sterile cockpit rule?

From rgl.faa.gov

  Sec. 121.542

  Flight crewmember duties.

  (a) [I omitted this, it's about noncritical (company) procedures]

  (b)
  No flight crewmember may engage in, nor may any pilot in command
  permit, any activity during a critical phase of flight which could
  distract any flight crewmember from the performance of his or her
  duties or which could interfere in any way with the proper conduct of
  those duties [...] such as [...] engaging in
  nonessential conversations within the cockpit [...]

  (c) For the purposes
  of this section, critical phases of flight includes all ground
  operations involving taxi, takeoff and landing, and all other flight
  operations conducted below 10,000 feet, except cruise flight.

One could argue that waving could distract the pilot taxiing, so according to the letter of the law, yes, you would violate the rule.

However, I think in the spirit of the rule it's fine, since it just means that the pilot not taxiing is paying attention to the surroundings as well. Reading between the lines, it basically says

  (a) During critical phases of flight, all crew should focus on flying, not selling cooked cardboard

  (b) Also, don't read the paper with a croissant while asking help with a crossword during said phases.

  (c) Critical phases of flight are when you're likely to read the bumper sticker on another jet.

I don't think a quick wave is quite as severe a violation as e.g. reading the paper (or, as the FAA calls it, reading publications not related to the proper conduct of the flight) during take-off. Compare it with a bus driver waving to a fellow driver or one reading the paper while driving. But then, if you do park your plane in a ditch while trying to wave to your mom, don't be surprised to be held fully liable.


How to calculate the best climb rate and glide rate?

Did you ever consider to look at the units in your calculation?

You can't just throw together some numbers and expect a correct result. Start by converting all input to the much more sane SI units and see how it goes from there. If you plug in the units instead of the numbers on the right side of the equation, you can check for correctness by comparing to the intended unit on the left side.

Hint: 1 Newton = 1 kg·m/s².


Where do I find the Weight Variants of an Airbus aircraft?

The weight variants for each model are listed in the aircraft's type certificate which describes the type's compliance with airworthiness regulations. You can look up the type certificates from regulators such as EASA and FAA.

As an example you can look at the document for the A330. Each of the minor models (-300, -200, and -200 freighter) has its own section, and the weights are listed in the "Technical Characteristics and Operational Limitations" subsection. Below is the table showing some of the A330-200 weight variants. The maximum takeoff (MTOW), landing (MLW), and zero-fuel (MZFW) weights are defined for each variant.


What kind of planes are on this old photo?

This is a formation of Curtiss-Wright AT-9s officially known as the Fledgling, but also known as the Jeep.

A high resolution version of the photo is available here: A formation of AT-9s over the Gulf of Mexico. USAF Photo

The National Museum of the US Air Force has restored an example painted to represent the aircraft in the foreground; more information can be found here: AT-9


Has Airbus planned to build a larger version of the A380?

Yes,

In 2012 they planned to build a larger version of the A380.

"Airbus says 1,000 seat A380 due 2020"

However, manufacturers do change plans from time to time, sometimes in response to market conditions. "Has planned" is not necessarily the same as "is planning". Those plans are not currently (8 Jan 2015) being pursued and consequently, as time goes by without a resumption of those plans, it is increasingly likely that any target dates in those plans may no longer be attained.

If you want to know do Airbus in January 2015 have active plans to build a larger version of the A380 - that would be a new question.


Is required that your alternate airport has approaches other than GPS approach?

See 9.5 of the referenced document:

  9.5 Contingency Planning for Alternate Airport.
  9.5.1 Alternate Airport Considerations. For the purposes of flight planning, any required alternate airport must have an available instrument approach procedure (IAP) that does not require the use of GPS. This restriction includes conducting a conventional approach at the alternate airport using a substitute means of navigation that is based upon the use of GPS. For example, these restrictions would apply when planning to use GPS equipment as a substitute means of navigation for an out-of-service very high frequency omni-directional range (VOR) that supports an instrument landing system (ILS) Missed Approach Procedure (MAP) at an alternate airport. In this case, some other approach not reliant upon the use of GPS must be available. This restriction does not apply to pilots
  with navigation systems meeting the requirements below.

  9.5.1.1 For flight planning purposes, TSO-C129( ) and TSO-C196( ) equipped users (GPS users) whose navigation systems have fault detection and exclusion
  (FDE) capability, who perform a preflight RAIM prediction at the airport
  where the RNAV (GPS) approach will be flown, and have proper knowledge
  and any required training and/or approval to conduct a GPS-based IAP, may
  file based on a GPS-based IAP at either the destination or the alternate airport, but not at both locations. At the alternate airport, pilots may plan for applicable alternate airport weather minimums using:

  Lateral navigation (LNAV) or circling minimum descent altitude
  (MDA);
  LNAV/vertical navigation (VNAV) decision altitude (DA), if equipped with and using approved barometric vertical navigation (baro-VNAV) equipment;
  RNP 0.3 DA on an RNAV (RNP) IAP, if they are specifically authorized users using approved baro-VNAV equipment and the pilot has verified RNP availability through an approved prediction program.

  Note: If the above conditions cannot be met, any required alternate
  airport must have an approved IAP other than GPS that is anticipated
  to be operational and available at the ETA, and which the aircraft is
  equipped to fly.

  9.5.1.2 Pilots with WAAS receivers, TSO-C145( ) or TSO-C146( ), may flight plan to use any IAP authorized for use with their WAAS avionics as the planned
  approach at a required alternate, with the following restrictions. When using
  WAAS at an alternate airport, flight planning must be based on flying the
  RNAV (GPS) LNAV or circling minima line, or minima on a GPS approach
  procedure, or conventional approach procedure with “or GPS” in the title.
  Properly trained and approved, as required, TSO-C145( ) and TSO-C146( )
  equipped users (WAAS users) with and using approved baro-VNAV
  equipment may plan for LNAV/VNAV DA at an alternate airport.
  Specifically authorized WAAS users with and using approved baro-VNAV
  equipment may also plan for RNP 0.3 DA at the alternate airport as long as
  the pilot has verified RNP availability through an approved prediction
  program. Code of Federal Regulation (CFR) Part 91 nonprecision weather
  requirements must be used for planning. Upon arrival at an alternate, when the
  WAAS navigation system indicates that LNAV/VNAV or localizer
  performance with vertical guidance (LPV) service is available, then vertical
  guidance may be used to complete the approach using the displayed level of
  service.


How long is a climb leg in a step-climb cruise flight segment allowed to take, according to regulations (FAA/EASA)?

The FAA's IFR handbook sheds some light on what they expect (page 2-48)

  If the pilot receives the term “climb at pilot’s discretion” in the
  altitude information of an ATC clearance, it means that the pilot has
  the option to start a climb when they desire and are authorized to
  climb at any rate, and to temporarily level off at any intermediate
  altitude as desired, although once you vacate an altitude, you may not
  return to that altitude. When ATC has not used the term nor imposed
  any climb restrictions, pilots should climb promptly on acknowledgment
  of the clearance. Climb at an optimum rate consistent with the
  operating characteristics of the aircraft to 1,000 feet below the
  assigned altitude, and then attempt to climb at a rate of between 500
  and 1,500 fpm until the assigned altitude is reached.

Its somewhat contradictory, first they say you can climb at any rate you want but then they say in the absence of any specific instructions you should climb at an "optimum" rate to within 1000 feet of your assigned altitude and then climb between 500fpm and 1500fpm.

This is specifically spelled out in the AIM with more or less the same language

  When ATC has not used the term “AT PILOT’S DISCRETION” nor imposed any
  climb or descent restrictions, pilots should initiate climb or
  descent promptly on acknowledgement of the clearance.Descend or climb
  at an optimum rate consistent with the operating characteristics of the
  aircraft to1,000 feet above or below the assigned altitude, and then
  attempt to descend or climb at a rate of between 500 and 1,500 fpm
  until the assigned altitude is reached. If at anytime the pilot is
  unable to climb or descend at a rate of at least 500 feet a minute,
  advise ATC.

Interestingly this adds the note that if you can not climb at 500 f/min then you should alert ATC. I would take this to be a minimum climb rate.

There is at least one permitted case of the drift climb that I know of. The Concorde operated above all other commercial traffic and aside from the SR-71 there really was no one else up where they were. As such once they passed a specific floor they were allowed to drift up freely as they burned fuel. This was, as far as I know unique to their operation and specifically permitted. They had a lot of other specific addendums due to their unique design.


What is the minimum glide ratio of a motorized glider?

The minimum glide ratio of any aircraft is zero. Just put it into a vertical dive. Of course this is not sustainable; either you overspeed or collide with the ground.

in order to be certified as a powered sailplane (that is bureaucrat talk for motor glider), EASA CS-22.1 demands a ratio of weight to span squared of less than 3. The second limit is a maximum weight of less than 850 kg. That the code gives the maximum weight in Kilogramms and not in Newtons shows that the weight figure limit of 3 needs to be calculated with the mass of the aircraft, not its weight.

Initially, the criterium was a minimum sink rate of less than 1.0 m/s. That number was raised to 1.2 m/s when the first batch of glassfiber models could not meet that target. The mass per span squared rule came into force in 2003.

The defining criterium for an ultralight depends on the local rules and is a maximum take-off mass of 300 kg or less for single-seaters or 450 kg for two-seaters in Europe. Within the ultralight class there is no motorglider category.


why do all planes hold position when Air Force 1 is taxiing?

No doubt security has a lot to do with it. With only one vehicle supposed to move on the airport premises, everything else that moves can be easily spotted and classified as a potential threat, and resources dispatched to handle it.

If there are dozens of other aircraft and hundreds of cars and trucks moving around, this gets a lot harder.


What is this part between the Su-35's jet exhaust nozzles?

The long thing has RWR (Radar warning Reciever) on its sides and has a drogue parachute in the middle. This image shows the rear part open after deployment.

Image from airplane-pictures.net

Incidentally, the aircraft serial number is 901, while the one in your image has a number 902.


Has an unauthorized civilian ever tried to land on an aircraft carrier?

I'm not exactly sure whether this counts, but I think the landing of South Vietnamese Air Force Major Buang-Ly on USS midway using a Cessna O-1 Bird_Dog comes pretty close.

Though Major Buang-Ly was not a civilian, he has never seen a carrier before and the landing wasn't exactly illegal. It was permitted by Captain Larry Chambers during Operation Frequent Wind, who even scuttled helicopters on the deck to ensure safe landing.

The image below shows the aircraft as it comes to a stop.

Image from forum.worldofwarships.com


Could some kind of impact absorbing gels be introduced into the aircraft fuselage, to minimize impact damage on passengers & cargo?

Unfortunately, not to any great advantage.

An airliner travels at several hundred kilometres per hour; even when landing and flying at its slowest (which it does only for a very short time) it will still be travelling at a considerable speed.

At such speeds, any impact in a crash is likely to be characterised by two things (I've left aside fire, to concentrate on the matter of impact alone):

a very significant change in velocity (deceleration)
a release of a great deal of energy

The deceleration of an aircraft in flight that hits something will be tremendous. If you have 30 metres in which to decelerate from (say) 500 km/hr to 0, padding won't make any difference to the bodies being decelerated.

If the padding is resistant enough to prevent an object experiencing such a deceleration from simply continuing on its way and smashing through everything in its path, then the padding may as well be a block of concrete for all the softness it could offer.

On the other hand, if the padding not so hard as to smash the bodies that crash into it into pieces, then they will go straight through it and smash themselves to bits on the first harder thing they encounter.

In fact, at such decelerations, not only is there no middle way between too hard and too soft, any padding aiming for the middle ground would be simultaneously too hard (it would certainly cause catastrophic injuries to the bodies encountering it) and too soft (it wouldn't prevent them smashing into other objects).

Then, an impact of the kind you describe releases a huge amount of energy. The things involved in such impacts aren't so much as damaged as cease to exist. Everything stops being what it was. You might as well wish for padding to protect you when you're on the inside of an exploding bomb.

Perhaps you were referring to lesser impacts that would be survivable with some protection, which is reasonable. Indeed, an aircraft can readily survive turbulence that breaks the bones and heads of passengers not wearing seatbelts.

But in this case, the idea sadly fails as not very practical.

How much damage would 300 or so exploding gel pods, or airbags, do to passengers? Once again, that's a release of quite a lot of energy.
How much damage would they prevent, compared to say, just wearing seatbelts?
How much would they interfere with the subsequent evacuation?

They simply wouldn't procure any advantage, or at least, only at the cost of a much greater disadvantage.


Because there is no link between the wheels and the engine.

When the car is moving slowly, wheels turn slowly so the engine must turn slowly as well. However piston engines do not work below certain RPM, so the gear switching must be implemented even for small cars.

Propeller can always turn at the speed sufficient to sustain the engine running. If the plane moves too fast (or must stand in place), wheel brakes can be applied.


Why apply resolutons in data words for ARINC 429 bus

The ARINC 429 Word resolution tells you what value the LSB corresponds to. You can also tell what the resolution should be by looking at the Range and Significant Bits.

It doesn't describe the actual electrical signal.


Why do some aircraft carriers have an upward starting runway?

The upward slope on the runway is also known as a "ski jump", and it is to give VSTOL (Vertical or Short Take Off and Landing) aircraft get aloft on the short carrier deck. Carriers without this use aircraft catapults to quickly get airplanes up to flying speed.

The advantages of the ski-jump are its simplicity, which means the carrier has lower build and operating costs. The drawbacks are that VSTOL airplanes are generally more limited in their capabilities, the airplanes that are launched by catapults pack a lot more punch.


Float just means that that value will vary depending on ambient temperature pressure etc. It is not controlled. E.g. on n2 control, if n2 goes down then the control puts in more fuel and if n2 goes up then the control puts in less. But if n1 changes (maybe because ambient temp changed ) the control does nothing. If n1 goes down then so be it.


What are the pros and cons of putting a propeller immediately before a slipstream pylon vs. immediately after

If it's for something like an airplane or powered glider, for best thrust efficiency and noise level, you want the prop on the front. If behind, the turbulence from the pylon causes both efficiency loss and a loud buzz as the blades pass through the pylon's wake. This is a bigger deal than the effect of the prop's wake hitting the pylon when mounted forward.  The characteristic buzz sound that the Lake Buccaneer makes is from having the prop behind the pylon.
For an engine on skinny pylon with little frontal area, the difference between pusher and tractor is not that much, so noise effects are probably a bigger issue.  The efficiency difference grows when the body in front of or behind the prop gets large. From an article by designer Peter Garrison in FLYING:

Now, how to compare this with the efficiency efficiency of a pusher propeller? For this I'm obliged to turn to books, since it's not possible to do a rule-of-thumb calculation from basic physical principles, as it was for the tractor. In Roskam and Lan, Airplane Aerodynamics and Performance, there is a chart showing the effect of what you might call the occlusion ratio -- the ratio of fuselage diameter to propeller diameter -- on the efficiencies of tractor and pusher propellers. The efficiency of the pusher prop is lower than that of the tractor, but negligibly so, until the fuselage diameter reaches half the prop diameter, at which point the two curves begin to diverge. When the fuselage diameter is 60 percent of the prop diameter the pusher has dropped behind by about 3 percent; by the time the fuselage diameter is 70 percent of the prop diameter, the decrement is 8 percent. An equation is provided (it is also found in Dan Raymer's Airplane Design: A Conceptual Approach) that yields roughly the same result.

The Volmer Amphibian is a good illustration of this.  It had the option of doing either; you could design the mount to point the engine forward or backward.  Part of the attraction of the tractor option was it didn't limit the engine choices (you need an engine with thrust bearings for pusher installation if you want to install it that way, as well as a prop designed for pushers).
Having the prop forward is widely seen as more efficient, with better thrust for the same horsepower and a simpler installation.  I would say most Volmers were built as pushers however, mostly due to discomfort with having a propeller blade tip passing a foot and a half behind the pilot's head (I'd not be too happy having to put the thing into trees with that head chopper right behind my head, and if I was building one, there is no way I'd have the prop on the front).
The consensus however, seems to be that the tractor arrangement is superior performance wise, while the pusher is safer.
In the case of an electric motor glider (which I assume is what you are contemplating) there is another factor, which is the desirability of an aft folding propeller if the mount is fixed.
Recognizing that the efficiency difference may not be enough to worry about although the noise effects could be significant, if the pylon retracts, I'd put the prop on front. If the pylon is fixed and the prop feathers, I'd also put it on the front.  If the pylon is fixed and the prop folds, then it goes on the back.


What is the angle $\epsilon_{cl}$ in this diagram?

This is the downwash angle. Consider it an angle by which the wing deflects the airflow behind it.
Traditionally, this angle is designated $\epsilon$. Why the $cl$ index I don't know; perhaps it reinforces its direct dependency on the wing lift coefficient, as you can see from the formula; or that this is the 'pure' downwash only dependent on the wing. In fact, every document should have a Nomenclature section which explains the designations.
Apart from $C_L$ and $A$, the effective downwash angle will depend on the distance from the wing and spanwise location. Typically, the point of interest is the tailplane: downwash reduces its effective angle of attack. The coefficient $1.62$ probably accounts for the tail location ($z_h$ etc.), but you need to double check how this $\epsilon$ is used. (You will find different coefficients in the literature).
Obviously, this will affect trimming. But downwash also has a significant effect on stability, because it changes dynamically with lift. As the angle of attack / lift (of the wing) increases, downwash also increases. Therefore, the horizontal tail experiences a reduced variation of angles of attack compared to the wing. This is further complicated by the fact that this reduction is delayed by the time it takes for the airflow to reach the tail. Generally, these are positive effects, but they must be accounted for in stability analysis.


What is the name or part number of the Bose 'Lemo' aviation headset connector?

The connector on the end of the headset's cable is a P-Series. Specifically it is PN PAG.M0.6NL.AC65NZ. You will need to purchase the strain relief separately. If you are looking for the socket Then you need PN PRG.M0.6NL.LC65N for inline connections or PTG.M0.6NL.LC65N for Panel connections.

Unless you own or want to buy the crimp tool, you will need buy solder contacts (and buy extras if you've never soldered these before.) In my experience, universal crimpers don't work well enough with LEMO parts. If you are doing panel mount consider how important FAA compliance is in your situation and consider paying an avionics guy or consulting a DAR (or whichever governing body and official is salient to you.)

UPDATE: On closer reading of the P series catalog, the first letter of the last sequence determines whether the connectors are crimp or solder. A and L indicate male and female solder, respectively. C and M represent male and female crimp. The part numbers provided above are, therefore all for solder connection.

Note that it is possible Bose had a special variant made for them. In most cases this means special keying to make the connector proprietary. It is possible file keys off of generic connectors but that is not really recommended. I disclaim any responsibility if you waste $23 or have an uncomfortable conversation with your FSDO or DAR. Note also that these parts can be a bit hard to research because they are actually made by Redel, a subsidiary of LEMO. Calling these things LEMO connectors is a bit like calling a Porsche 911 a Volkswagen 911.

I've included links to digikey and mouser in my references. Either site is a great source for parts in the US and should stock all the parts I've referenced.

Additionally, here is the P-series catalog.


If a circling airplane (AC-130) fires a bullet how does the plane's trajectory alter the shell's flight path?

The bullet leaves the barrel with the combined velocity of barrel muzzle velocity plus the instantaneous aircraft true air speed velocity (actually, the instantaneous true air speed velocity of the tip of the muzzle). That puts the velocity vector of the bullet ahead of the line of the barrel (ahead of the 90 degree wing line). The fact that the barrel is rotating in inertial space is irrelevant. Whether the aircraft is straight and level, turning towards the tank, or away from it, if, at the moment the bullet leaves the muzzle, it is traveling in inertial space towards the tank, (and sufficiently above it for gravity drop) it will hit it.

And since the bullet's velocity leaving the barrel is a simple vector sum of the muzzle velocity, and the aircraft's instantaneous velocity at that instant. The velocity vector of the aircraft before, (or after), the bullet leaves the barrel is of no relevance.

So if the aircraft is moving due North at 100m/s and the muzzle velocity is 1000m/s due East relative to the aircraft, the bullet is actually traveling
SQR(100^2 + 1000^2) = 1004.98 ~1005m/s in a direction slightly North of due east by an amount equal to the arctangent of 100/1000 or ArcTan(0.1) = 6.345 degrees
So the bullet is traveling 1004 m/s on a heading of 90-6.34 degrees = 83.66 degrees true.
So, to hit the tank, the pilot has to fly so that the gun barrel is pointed behind the tank by 6.34 degrees (and above it by a sufficient amount to account for gravity drop)


How can pilots identify, in flight, the cracked layer(inner/middle/outer) from an impaired windshield?

It is possible to identify whether the crack affects the inner layer by sliding over it with nail or something sharp like pen. If the layer is cracked, the slight indenting in the surface can be felt.

As far as I can tell, there is no way to tell whether the outer or middle layer is affected with any useful degree of certainty. It is also not possible to ascertain how many layers are cracked. So usually the procedure is so that if the inner layer is not affected, you can continue and fix the issue at destination and if the inner layer is affected, you have to conservatively assume all layers may be affected and descend.


Why does the vortex created by wing affects its own angle of attack?

The wingtip vortices create both upwash and downwash; The downwash lies within the wingspan and affects the wing angle of attack while the upwash region lies outside the wingspan and can be utilized by another aircraft (or bird) flying behind and above the wing.

The flow induced by the downwash reduces the effective angle of attack of the (finite) wing and causes the induced drag.

See if this image clarifies your doubt.

Source: aerospaceweb.org

Consider the upwash before the wing and downwash after the wing (section).

Source: theairlinepilots.com

As it can be seen, the airflow in front of the wing is slightly directed upwards by the upwash. Now, the angle the wing makes with the horizontal datum (i.e. relative airflow) is the same.

However, the airflow is slightly turned upwards and the wing sees the air coming at it at a different angle compared to the relative airflow. As a result, the effective angle of attack (defined as the angle of attack that lies between the chord of an airfoil and the effective airflow) is reduced, so that the relative and effective airflow looks something like this:

Source: theairlinepilots.com

This difference between the relative and effective airflows is what that causes the induced drag.

Source: theairlinepilots.com


How are rocket engine nozzles able to survive very high temperatures without melting?

There is actually quite a lot of information on the subject in the Braeunig web site Basics of Space Flight. To give the salient points:

Liquid-fueled rocket engines

Both the nozzle and the combustion chamber itself need to be cooled. Although most of the thermal energy produced is ejected with the exhaust, some of it will indeed push hardware temperatures up if not checked. Techniques include:

Regenerative cooling, where the propergols (both propergols, or just the fuel) are pumped through a jacket around the nozzle before going into the combustion chamber. This cools down the nozzle, and heats up the propergols that may be cryogenic in nature. This is what was used in the Saturn Vs' Rocketdyne F-1 engines, and the Space Shuttle main engines.
Dump cooling, similar to the above but the fuel used to cool the nozzle is dumped overboard instead of being fed into the combustion chamber and being used as, well, fuel.
Film and transpirative cooling, where a thin film of coolant or fuel is created near the chamber wall.
Ablative cooling, where part of the combustion chamber or nozzle wall is sacrificed. As the material is melted or otherwise burned away, it absorbs some of the thermal energy, thus saving whatever is behind it.
Radiation cooling, where nozzle design is such that heat has time to be evacuated through the part's exterior wall. This is used mainly in small engines, not main.

Solid-fueled rocket engines

No information available. Nothing. Zilch. Nada.

It would seem that the nozzle and combustion chamber materials just need to be strong enough to withstand the heat from the burning gasses. It is perhaps worthwhile to note that solid rocket engines are designed to burn just one single time, and for a relatively short period of time (even the Space Shuttle boosters were extensively overhauled before being put back into service, with any necessary parts changed). Rocket engines need to withstand working conditions for just minutes, instead of the thousands of hours an A/C jet engine turbine would be expected to work without failure.

It would also be reasonable to assume -though this is strictly something I am making up on the go, with much hand waving- that of the techniques described above for liquid-fueled rocket engines, at least two could be easily adapted to solid engines:

Film cooling, with an extra tank of cooling liquid on board.
Ablative cooling, with some refractive material used to coat the inner surface of the nozzle.


Is it permitted to land amphibian plane in the ocean on Californian coast?

Seaplane air taxis only work where the logistics situation and market can support a business case for that kind of service.  It's an expensive way to travel, so there has to be some kind of benefit that makes it worth the cost to the traveler.

This works in the Seattle area and the Lower Mainland of British Columbia where you have large city centers with nearby destination locations that require over-water travel to get to, and business travelers willing to pay extra for fast waterfront-to-waterfront travel.

Vancouver BC has a thriving air taxi market because people want to get across to Vancouver Island quickly, especially Victoria BC, the provincial capital, and the business traveler demand supports seaplane operations up to Twin Otter size.

California? Way cheaper to drive, or go taxi-airport-taxi.  In Vancouver BC or Seattle, a seaplane air taxi service is competing with ferry boat service so it has a serious leg up that makes the ticket price worthwhile. Not so much down south on a contiguous coastline where there are both land and air alternatives.

So bottom line is, there's no money to be made doing it.


Why would a helicopter hold a 'nose-up' in hover?

This screen grab is from a few seconds before yours was taken. No pitch is evident here.

Sketched above is rope angle and camera position (based on the staircase in both frames).

I think it's just the camera angle used that makes it look pitched combined with the rope's angle in the wind.


How can I calculate the drag coefficient for a given wing design?

You may visit http://airfoiltools.com/airfoil/details?airfoil=clarky-il
You can estimate the value of Cd from the plots. For different angles of attack, the Cd and Cl varies. So, you will have to select one based on your requirement.


If a winglet disconnected from an airplane mid-flight, what would be the consequences?

this actually happened to the Rutan around-the-world flight, where one winglet was shaved off against the runway pavement during the takeoff roll. the pilot then stabbed the controls to overstress the remaining winglet, causing it to break off during climbout. the purpose of the winglet is to increase the apparent span of the wing by blocking airflow out from under the wing and over & into the airflow over the top of the wing, so an aircraft with one winglet on and one off would perform as if the wingspans on either side of the fuselage were several feet different.


We can look at financial data from airlines to estimate these figures.

In addition to fuel, there will also the extra duty time for the crew, some delay in schedule, and extra flight time on the aircraft. The delay in schedule can be difficult to estimate, but other costs of operation can be estimated. A short flight would take 1.5 hours, and the go around might take 0.2 hours.

Based on the financial data, an MD-83 might cost about 6000 dollars/hour to operate. This includes all direct operating expenses. This means that the regular flight would cost about 9000 dollars to operate, and a go around would cost about 1200 dollars. Since a go around uses a lot of fuel, the figure may be a bit higher.

The figures for a Boeing 747-400 show about 15000 dollars/hour to operate, and a Boeing 777-200 about 12000 dollars/hour to operate. That would make an 8 hour flight 120,000 dollars and 96,000 dollars respectively, with go arounds costing 3000 and 2400 dollars respectively. Obviously, for longer flights, the go around will cost less proportionally than for a shorter flight.

As DeltaLima mentioned, the cost of not doing a go around (which includes making this decision early enough) can be substantially higher. Loss of or even just damage to an aircraft will cost much more time and money.

To see if these numbers make sense, this report mentions that an empty MD-83 would need 1000 kg of fuel for a go around and new approach. It also mentions that a ferry flight from Paris Orly to Olbia, Italy, would normally require 6800 kg including reserves. If reserves are about 1600 kg, this would mean that the flight would use 5200 kg of fuel.

If jet fuel costs 3 dollars per gallon, this comes out to 985.72 dollars of fuel for a go around, and 5125.73 dollars of fuel for a regular flight. This figure seems reasonable along with the figures above.


How do aircraft engine manufacturers achieve a higher bypass ratio while still meeting the thrust requirements for a given aircraft?

Early turbojets were so inefficient that adding a fan was considered but not implemented because that would had made the engines even more sluggish and narrowed the operating limits even more. If you compare the Jumo 004 with the EJ200, you will find that both are of similar size, have  8 compressor stages, but vary widely in their compression ratio and thrust (3.2 vs. 26 compression ratio and 9 vs. 60 kN dry thrust).

When compressor flow was better understood, turbine temperatures and pressure ratios rose, the excess power delivered by the engine core rose and allowed to drive a second turbine and shaft; initially with bypass ratios as low as 0.25. If you compare the overall pressure ratio with the bypass ratio, you will certainly spot a trend:

Engine             compressor       pressure ratio     bypass ratio
RR Conway        7LP, 9HP stages       14  :1             0.25:1
P&W JT3D      2fan, 6LP, 7HP stages    12.5:1             1.42:1
GE CF6-6      1 fan, 1LP, 16HP stages  25  :1             5.8 :1
RR RB211-535  1 fan, 6IP, 6HP stages   25.8:1             4.3 :1
GE 90         1 fan, 4LP, 9HP stages   42  :1             9   :1
RR Trent XWB  1 fan, 8IP, 6HP stages   52  :1             9.3 :1
RR Ultra Fan                          >70  :1           >15   :1 (projected)

A more efficient core allows to leave more energy in the exhaust past the high pressure turbine, so the low pressure turbine can extract more power to drive a larger fan.


Where can I find a collection of maximum range at maximum payload values for all aircraft types?

Perhaps the DVB Bank report "An Overview of Commercial Jet Aircraft 2013 - 2014," contains the information you are looking for.

It contains a type description, performance data, world fleet data and engines for many aircraft types, as well as payload-range diagrams for each aircraft category.


What's the difference between Rotation speed vs takeoff speed?

Based on the speeds that you are talking about, it isn't a turbojet definition that you are looking for.  The definition for $V_R$ that you gave is for turbojets.

In small GA airplanes, I teach my students to rotate around $1.3V_{S0}$ which really means to slowly bring the nose up to the takeoff pitch attitude.  Under no circumstances do I want them to yank the airplane off the ground.  If done correctly, the airplane will naturally lift off when it is ready to.


How does the Airbus auto takeoff system work?

This is a quote from Airbus's press release:

  Rather than relying on an Instrument Landing System (ILS), the existing ground equipment technology currently used by in-service passenger aircraft in airports around the world where the technology is present, this automatic take-off was enabled by image recognition technology installed directly on the aircraft.

So it sounds like the plane is using the same technology used in autonomous cars, which are able to use computer vision and cameras to navigate traffic.  Except in this case the plane just had to keep center-line and rotate at the appropriate speed.

It is also shown in Airbus's video, ATTOL: Autonomous Taxiing, Take-Off and Landing test flight:


In subsonic flow the air can react to the approaching vehicle since the pressure field around it extends forward, too. This means that a suction area on one side of the fuselage or wing will already start to pull molecules in before they reach the vehicle itself which causes this suction. A round nose allows the flow to come from a range of angles without creating too much drag. Aerodynamically speaking, the stagnation point can be moved without problems.

In supersonic flow, the air has no indication of the approaching vehicle. The first contact will cause a sudden change in direction, called a shock. For drag reduction it is important to make the shock as weak as possible, which means that the change in direction should be as small as possible. This can best be achieved by a slender, pointy tip.

Note the downward position of the intake cone of the SR-71 engine nacelle in the picture below: It is angled so that at Mach 3.2 the cone is symmetrical to the oncoming flow (which gives you a pretty good indication of the angle of attack of the whole plane).

SR-71 during take-off (picture source). Not only is the cone angled downward, but also canted in because the flow is pressed sideways by the aircraft's forebody in supersonic flight.

In hypersonic flow (Mach > 5) a blunt nose might again be preferable if the nose's materials put an upper limit on aerodynamic heating. A pointed tip will produce an attached shock which will heat the tip to something close to the stagnation temperature of the flow. A blunt nose, however, will cause a separated shock. This creates more drag and a higher amount of heat overall, but allows to spread this heat over a larger area and dump most of it into the air, producing lower peak loads. The Space Shuttle had such a blunt nose, since drag minimization is not a priority for a re-entry vehicle.


Is it considered good or bad practice to raise the flaps right after touchdown?

You should wait until clearing the runway before performing any non-essential checklist items because you are still in a critical phase of flight and at a relatively high risk while still on the runway.  You should focus 100% of your attention to controlling the airplane (don't stop flying the airplane until you come to a complete stop) and watching for other traffic (or someone crossing the runway in front of you) that might be a hazard.
There is also the possibility that in a retractable gear airplane you could accidently retract the gear if you are moving things while still preoccupied with landing.  Once you exit the runway and come to a complete stop, you can devote the proper attention to the after landing checklist so will be more likely to complete it correctly without missing any items that may become an issue on your next flight.
That being said, follow the guidance in your POH.  Sometimes there are abnormal situations that actually call for this, like voretaq7 mentions in his answer, the Cherokee POH references it as a short field landing technique.
FAA Guidance
The FAA also covers this in AC 91-73B - Parts 91 and 135 Single Pilot, Flight
School Procedures During Taxi Operations.   It says (in part):

7. SINGLE-PILOT PROCEDURES.
a. General.
...
In addition, upon  landing, no items should be changed or moved until
the entire aircraft has crossed the respective  runway’s hold short
line.
...
NOTE: After the entire aircraft crosses over the landing runway’s hold  short line, conduct after-landing checklist items, based upon
company  procedures, before contacting ATC for taxi instructions.

You could also fail a checkride for doing this
The PTS also repeatedly stresses the  objective:

Utilizes after landing runway incursion avoidance procedures.

To figure out what they mean by that, we can look at their Runway Incursion Avoidance material, which says:

Finally, after landing and upon exiting  the runway, ensure your
aircraft has completely crossed over  the runway hold markings. Once
all parts of the aircraft have  crossed the runway holding position
markings, you must hold  unless further instructions have been issued
by ATC. Do not  initiate non-essential communications or actions until
the  aircraft has stopped and the brakes set.


Is locking the cockpit door from inside is a normal procedure when one pilot leaves?

For most modern, large commercial passenger planes, there is an automatic lock, which then requires the PNF (Pilot Not Flying and outside of the cockpit) to enter an unlock code, or more usually, for the PF (Pilot Flying, and hopefully inside the cockpit) to remotely unlock the door.

The emergency access code typically sounds a cockpit warning buzzer and has a delayed operation, allowing the PF to override this in case of an unwanted, erm, "visitor", yet at the same time, allowing access to the PNF in case of PF incapacitation.

Commercially, three pilots (or two pilots and a flight engineer) on each flight are no longer economically viable for almost all airlines.  Indeed, most couldn't host a third person comfortably for the whole flight - jump seats are fine for short bursts, but not for a long-haul flight, for example.

Therefore, most airlines are now adapting their cockpit manning procedures to ensure another member of the flight crew (typically a flight attendant) joins the PF before the PNF leaves the cockpit.


What is the definition of visibility as seen in aviation weather reports?

All my quotes for this post comes from FAA Order 7900.5C, the Surface Weather Observing Guide.

Visibility is defined as "Visibility is a measure of the horizontal opacity of the atmosphere at the point of observation and is expressed in terms of the horizontal distance at which a person should be able to see and identify specific objects."

All METARs report Prevailing Visibility, which is: "Prevailing visibility is the greatest visibility equaled or exceeded throughout at least half the horizon circle, which does not necessarily have to be continuous. This is the visibility that is considered representative of visibility conditions at the station."

Automated stations, generally report a max visibility of 10 SM. Now if you look at stations that are completely manual, i.e. KBJC(when I worked there it was a completely manual station), we'd report anywhere up to 70SM or higher visibility, due to our visibility markers.

-RA can often be easily seen through, RA or RA+ do become harder to see through, and as always, it can be dependant on where the -RA is, if it's only in a tiny quadrant of the horizon circle, it can often be a greater visibility.

[Edit Post comment about RA]: Sorry, used a few more abbreviations. SM = Statute Miles, which is like a regular mile that most people use in their daily lives. It's depicted as SM, due to most other things in aviation being in Nautical Miles.

-RA, RA, +RA, are the various descriptors for Rain. -RA means light rain, which if just using vis concerns is defined as, "From scattered drops that, regardless of duration, do not completely wet an exposed surface up to a condition where individual drops are easily seen." RA, is Moderate Rain, defined as: "Individual drops are not clearly identifiable; spray is observable just above pavements and other hard surfaces" and +RA is heavy Rain, "Rain seemingly falls in sheets; individual drops are not identifiable; heavy spray to height of several inches is observed over hard surfaces."

Also, METAR is the type of aviation weather report. METAR's are the hourly/standard report, and then there's SPECI's which if certain changes occur in conditions, from Freezing Rain, to changes in visibility or cloud ceilings, to massive wind shifts, to thunderstorms, to other factors, can be produced outside of the hourly/regular report.


How can I get an FAA Class 3 medical re-examination?

There are two processes you can go through if your medical is denied - one is to appeal the denial to the FAA (which you'd do if your AME messed up and you can prove they're wrong), the other is to reapply (which is probably what you'll want to do if you get denied).

When you reapply you're basically starting the medical certification process over from the beginning. You can reapply right away if you want, but practically you would reapply when you've corrected whatever condition(s) caused you to be denied, and go back to your AME with documentation showing that your condition has been corrected (or determined to be benign).

I assume based on your question that you've had to check the "Frequent or Severe Headaches" box, so you will continue to check that box, and may require a Special Issuance medical because of that -- your AME can give you more details if you wind up in this situation.

If you do get denied talk to your AME (and any other doctors you may be seeing) about your next steps before doing anything - obviously medical issues are serious not just because they keep you out of the sky but because your health is important.

You may also want to take advantage of AOPA's Pilot Protection Services - they have folks on staff who are experts at navigating the FAA medical process and can help you out. It could be worth it if you anticipate you'll need assistance with medical certification over the long haul.


What is the hierarchy of aviation regulatory bodies?

As pointed out by vasin1987 in a comment to the question, each country's regulatory body has control of that country's airspace: These agencies exist in a "mesh" of coequals as opposed to a hierarchy.

The EASA is a EU agency and applies to all of EU, very similar to how the FAA is a US agency that applies to all of the US.

ICAO, in turn, deals primarily with situations where air traffic crosses regulatory borders. In its own words, borrowing from the page About ICAO on their web site,

  The International Civil Aviation Organization (ICAO) is a UN specialized agency [which works] to reach consensus on international civil aviation Standards and Recommended Practices (SARPs) and policies[.]

Like pretty much the rest of the UN, the ICAO is more a forum for cooperation between regulatory bodies than a regulatory body in its own right.


Are there any safety features to prevent reversible-pitch props from reversing in flight?

Beta props are pretty rare on anything smaller than Twin Otter or King Air or Porter or Turbo Beaver.  Can't speak for MT's system, but most beta mode systems use mechanisms to switch control of propeller blade angle from the propeller rpm governor to the throttle.  Beta mode is the mode of throttle or power lever control of blade angle, with engine torque controlled by a governor system of some kind to regulate rpm.

Beta mode is very similar to turbine helicopter collective control, where a lever, the collective, directly changes rotor pitch and a governor system regulates rotor rpm by adjusting engine torque.

Beta mode is normally entered just above flight idle (flight beta) once the propeller speed governor is no longer regulating blade angle (blades at fine pitch stops).

There is normally some kind of detent or gate that requires a deliberate movement or unlatching to move below flight idle (the Twin Otter requires you to twist the throttle grips - on others there are finger triggers).

Also, some turboprops have beta lockout systems that prevent power lever movement below flight idle until you're on the ground.  But a lot of airplanes don't and can be put into ground beta in flight if the flight idle gate or latch is deliberately operated by the pilot.

During the Twin Otter program there was some controversy at DeHavilland Canada because demo pilots were using ground beta (coming into DISC - blades flat, like a disc) to make crazy steep descents (I've also heard of Porter pilots doing it).  A very dangerous thing to do, because if the prop doesn't want to come out of beta mode when you move the lever(s) back up, you are dead meat.


Why is the missed-approach course for the "RNAV (GNSS) - A" approach to runway 28 at ENSB shaped all funny?

If you look at satellite imagery it looks like you have very high terrain to the west of the runway. The water would be the primary area available for a climb back to obstacle clearance altitude. Looks like the MAP just routes you with sufficient time to climb to the MA altitude.

(Google Maps)


Would there be any further restrictions on the Zapata Flyboard Air than current FAA regulations for ultralight aircraft?

If the Flyboard Air meets the definition of an ultralight from 14 CFR 103.1 then only part 103 regulations would apply. 103.7 says that ultralights are exempt from airworthiness, registration and pilot certification requirements, and 91.1(e) says that general flight regulations don't apply to ultralights.

Based on the specifications on Zapata's website, there are two models: the Flyboard Air EXP and the Flyboard Air UL. The EXP doesn't meet the part 103 requirements (its fuel load and top speed are too high) but Zapata says the UL was designed to comply with part 103 and the quoted specifications do seem to be OK.

Assuming that you're fine with the UL model there are still two points in part 103 that might be an issue for you. First, the stall speed requirement in (e)(4):

  (4) Has a power-off stall speed which does not exceed 24 knots
  calibrated airspeed.

I don't know how the FAA would define a "stall" for a Flyboard and their detailed guidance on part 103 (dated, but seems to be still current) doesn't clarify it. It does say that a "recognized technical standards committee" can confirm that the requirement has been met, but I don't know who that means. You might want to ask Zapata how the UL complies with this requirement (and how they documented it).

Second, you can't use an ultralight in some commercial activities. The FAA document lists activities that are allowed (e.g. airshow participation) and others that aren't (e.g. aerial advertising). If you plan to use it only for private recreation then that doesn't matter, of course.

Finally, note that the FAA's document says that if you "encounter" an FAA field inspector for any reason it's up to you to prove that the ultralight meets the definition in 103.1. If you can't, they'll consider it as an aircraft for compliance/enforcement purposes. Before making your investment, I'd make sure that you're confident you can prove it really is a part 103 ultralight. If you aren't sure that you have the right information to do that, you could contact your local FSDO and ask them to review whatever you have and tell you if they would be satisfied.

(This answer is only about federal aviation regulations. If the Flyboard causes a lot of noise as mins mentioned, or disturbs people or the environment in some other way then there could be non-aviation, state or local laws that would apply.)


Are there any plans, designs, or prototypes for an electric ground effect vehicle?

The primary limiter is this: with batteries of current design, an electric GEV that can lift itself and travel a useful distance consists mostly of battery mass, with little useful payload. This is because a pound of jet fuel packs a lot more punch than a pound of battery.


How can I tell if a G430 or G1000 has WAAS or not?

NOTE: as pointed out in the comments, none of these quick verification steps actually guarantees that the airplane you clambered into is certified for LPV approaches, or for IFR GPS usage at all!

On boot, a 430W will display that it's a 430W:

Aside from that, I'm sure there's a version info screen somewhere (on both G1000 and GNS430), but the best solution I can think of is to check the satellite status screen. I'm trying to find examples of a 430W displaying it, and failing, but on a G1000, you'll see this:

 (source)

If the G1000 supports WAAS, it'll display that under the 'SBAS Selection' header and you'll see satellites at the bottom numbered in the 100s - 124, 126, 129, etc - all the 100-series satellites are the WAAS augmentation satellites. The satellites augmented by WAAS will also have a "D" at the bottom of the signal strength column.


Are altimeters calibrated to ISA geopotential altitude or ISA geometric altitude?

The TSO for Air Data Computers is TSO-C106. It specifies for the minimum performance standard "SAE Aerospace Standard 8002, Air Data Computer - Minimum Performance Standard."

From AS8002:

  3.6 Altitude Reference:

  Calibration of the static air sensing mechanism for pressure altitude
  outputs (including baro-corrected if supplied) shall be to the
  geopotential altitude tables of U.S. Standard Atmosphere, 1976.

While this is a US standard, the FAA asserts it is in compliance with ICAO Doc 7488.

For RVSM, additional requirements are levied against the installation primarily focused on reduction of static source error (SSE). That guidance is available in AC 91-85A.

It's important to remember that absolute accuracy at altitude is not as important as everyone adhering to the same reference.


Is any device installed on airplane to measure wind speed relative to the ground, and its direction?

The "wind speed relative to the ground" would just be the (vector) difference between ground speed and true air speed:

 (image source)

Most aircraft do not measure ground speed and track directly with instruments installed on the aircraft. It can be measured with a Doppler radar (see Peter Smith's answer), which is only used on military aircraft (mostly helicopters) today.

Ground speed and track can be determined with external tools:

DME: The Distance Measuring Equipment can be used to measure distances to fixed radio beacons equipped with DME (usually VOR/DME or VORTAC). If you know the angle at which you are flying towards/away from/to this station, you can calculate ground speed from the change in distance. Some DME instruments display this:

(image source)

When tracking a VOR, you also know the true track angle required for computing the wind direction.
GNSS: A Global Navigation Satellite System like e.g. GPS allows precise determination of the aircraft's position. The ground speed can be calculated from the change of this position and the true track is simply the direction of change. A more accurate determination is possible by measuring the Doppler shift of the signal (thanks to bogl for pointing this out).
ADIRS: An Air Data Inertial Reference System as installed on airliners knows the aircraft's attitude and position based on integrating data from accelerometers and gyroscopes. It can be updated via GNSS, but would still provide data for ground speed and track without it.

Modern avionics can display the result of these computations directly:

left: Boeing 737 Navigation display (source), right: G1000 (source)


Why does GBAS broadcast Final Approach Segment data when SBAS does not?

The reasons GBAS and SBAS are the way they are goes back to decisions made in the early 1990's when the concepts were first proposed. When the push started for satnav approaches it was obvious that augmentation was necessary to meet the accuracy and integrity needed for approach procedures. The FAA tasked RTCA to develop the standards and that was delegated to Special Committee 159 (SC-159).
SC-159 is a very large committee with representatives from government agencies, airlines, aircraft manufacturers, general aviation, avionics suppliers, and pretty much anyone with an interest in the system. Because of the huge amount of work and the differing systems the work was broken out to separate subcommittees. So while there were some people working on both subcommittees, the subcommittees each took there own path.
GBAS was being promoted by the FAA to be a functional replacement to ILS with support for CAT I and eventually CAT II/III operations. This needed support of the airlines who were only willing to go along if it didn't add significantly to their costs (preferably it would provide capability where ILS wasn't feasible and give them additionally capability at little to no cost.) So a fundamental goal of GLS was to be as operationally similar to ILS as it could get - minimal crew training, minimal aircraft system changes.
That last bit is key as the ILS is a DAL A system tied to the autoland system which is very expensive to certify. The avionics solution to this is the multi-mode receiver (MMR), ref: ARINC 755. The MMR allowed for retrofit as it occupied the same package as the legacy ILS receivers.
The MMR added a GPS sensor (which wasn't standard in the early 90's) and it allowed for integration with the ILS and its interfaces. The first MMRs were just and ILS and GPS sharing a box. But later versions added a precision approach navigator (PAN). The PAN could use the ILS output busses to provide the "ILS Look-Alike" output. But the GPS needs the augmentation data. This is broadcast from the GLS ground station on a VOR/ILS frequency. So the ILS receiver (a software defined radio) is repurposed in GLS mode to receive and decode the VHF data broadcast (VDB) from the ground station. It can then provide the augmentation data to the GPS and the FAS data to the PAN.
The reason for the FAS data being broadcast and not being in the nav database is that database is located in the FMS, not the MMR and the FMS is not a DAL A system. It also follows the concept that the ILS/GLS is a stand-alone unit that can support a precision approach even if other systems have failed.
Conversely, SBAS was pretty much ignored by the airlines (they only added WAAS GPS receivers when ADS-B drove the need.) SBAS was championed by the general aviation community that want RNAV approaches into airports that didn't have good approach options - no ILS, maybe a VOR or NDB approach. An RNAV approach was a big step up. Due to the large number of small airports that desired the capability, SBAS was more cost-effective than a GBAS approach. It was also cheaper for the user as it was contained within the GPS navigator/FMS. The limited bandwidth of SBAS forces the procedure data to be included in the nav database. But SBAS will likely never go beyond LPV capability which is acceptable to the GA community.
So the different needs of the GBAS and SBAS resulted in the different solutions.


You have to think that your flap is a small wing by it's own. The fixation point of this wing, through which all loads must be transferred is at the leading edge. Then there is a moment created at this hinge by both the aerodynamic lift and the aerodynamic moment if your profile is not symmetrical. You can calculate this moment by calculating the lift $L_f$ and aerodynamic moment $M_{0_f}$ at the aerodynamic center and then adding them after multiplying the lift by it's lever arm which is one quarter of the flap chord $c_f$. For a unit length of flap you get the following :
$$ M_h = L_{f}*\frac{1}{4}c_{f} + M_{0_{f}} =\frac{1}{2} \rho c_{f} C_L{_\alpha} (\alpha +\delta) V_\infty^2 * \frac{1}{4}c_{f} + \frac{1}{2} \rho c_{f} C_{m_0}V_\infty^2 $$
For the second part of your answer, the first diagram is showing the moment exerted on the flap to keep it down while the second one is showing the moment applied by the flap on the wing. Newton's third law gives you everything else.


Does joystick position control bank angle in some Airbus aircraft? And what happens when the pilot deflects the joystick when wheels are on ground?

Does joystick position control bank angle rather than directly controlling aileron/spoileron deflection in some Airbus aircraft?

To complement @Bianfable's answer, in Normal Law Flight Mode, Airbus FBW families (including A220) command roll rate via lateral stick position up to the artificial spiral stability limit of 33 deg bank (for A220 it's 30 deg). Below 33 deg bank, the aircraft exhibits neutral spiral stability; beyond 33 deg bank, it exhibits positive spiral stability, and lateral stick position commands a steady-state bank angle up to the roll limit of 66 deg (for A220 it's 80 deg).

  Also, what happens when the pilot deflects the joystick when the all wheels are on the ground and the bank angle (or roll rate) cannot change substantially?

Upon landing, the Normal Law transitions to Ground Mode, whereby the stick inputs command direct control surface movements. For A320, the lateral control transitions from Flight Mode to Ground Mode in 0.5 sec on ground detection is met, as shown below:

  Also, if the pilot is landing and the left main undercarriage assemblies are not extended for some reason, when the wheels on the right main undercarriage assemblies touch the ground, will maintaining a strong right control input on the joystick help delay the left wingtip (or engine nacelle) from contacting the runway, or not?

From this German accident report, in the case of an asymmetric gear deployment, ground signal is generated if "both LGCIUs (Landing Gear Control Interface Unit) detect that one landing gear has been lowered and is under load, and the radio altimeter measures the height above ground as less than 50 ft".

Therefore, immediately upon touchdown, you can expect the FBW to partially resist roll motion; but after 0.5 sec, you will have to use lateral stick to hold the aircraft level until the airspeed is too low to do so.


Could you land a large airplane on short circular runways?

As a matter of physics, there's a certain amount of braking and steering force available to the aircraft after it lands.

Suppose the aircraft touches down moving due north, and continues clockwise around your circular runway. After a quarter-circle it travels due east -- but that means that enough braking force has been applied to reduce the northward component of its velocity to zero, while also giving it some eastward velocity.

If only that eastward force hadn't been applied, the aircraft would be at a halt now -- using less force than what's necessary for it to follow the circle.

So if the plane can keep itself on a circular runway, it will be even easier for it to come to a halt on a straight runway whose length is the radius of the circle.

(Also, the plan ignores that the critical factor in the length of runways is not landing but taking off -- there must be enough runway to brake down safely if the takeoff is aborted just before rotation. And taking off from a curved runway sounds even crazier than landing. If the runway is horizontal, the plane would become airborne in the middle of an uncoordinated turn...)


Do large aircraft accumulate water in their tanks?

AFAIK all aircrafts accumulate water in their tanks. Since you ask for large aircraft acccording to wikipeadia:

FAA definition of large aircraft

  The US Federal Aviation Administration defines a large aircraft as any
  aircraft with a certificated maximum takeoff weight of more than
  12,500 lb (5,700 kg)

EASA definition of large aircraft

  The European Aviation Safety Agency (EASA) defines a large aircraft as
  either "an aeroplane with a maximum take-off mass of more than 5,700
  kilograms (12,600 pounds) or a multi-engined helicopter."

Here is Airbus A340 draining process with explanations on youtube

Here you can find EASA regulations about draining https://www.easa.europa.eu/download/etso/ETSO-C76b_CS-ETSO_11.pdf

Here is FAA regulations about water draining
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC20-125.pdf

On FAA AC 20-125 p.7 states

  WATER REMOVAL/PREVENTION. Water is best removed from jet fuel by
  passing the through approved filtration/separation equipment. A
  two-hour settling period and the use of floating suction to drain fuel
  from the top of a storage tank are also recommended to help prevent
  water from being introduced into a fuel system. Water will readily
  settle-out of aviation gasoline; therefore, filters/separators are not
  required for water removal, however, they are necessary for removal of
  solids. The best means to minimize the amount of water entering a fuel
  system is the inspection and proper maintenance of equipment and the
  training of ground and flight personnel.

Also FAA AC 20-125, Water In Aviation Fuels, para 7 c suggests that it may be necessary to gently rock the wings of some aircraft while draining the sump in order to completely drain all the water.


The aircraft is one of many (5 or 6) SAML-Aviatik type "S" and type "A" Italians that flew in Argentina in the '20s. All were for civilian use. Most had Colombo or FIAT engines in line, but the one in the photo (type "A") was the only with a rotary engine (Le Rhone?) that flew in Argentina. It belonged to the Italian pilot Renato Balleri, who together with the American Henry Johnson made public shows of flights, acrobatics, parachute jumping and flight baptisms throughout the country.
Henry Johnson died in an accident one of those events, in the city of Quilmes, in 1934.
The images are of this same plane in the province of San Luis.

Here an Italian SAML-Aviatik A.2...


How does a subsonic jet engine intake design ensure correct air intake?

Subsonic speed makes the inlet self-regulating. Add blunt edges, and the inlet works for a wide variety of engine and flight speeds, as it should.

An inlet is always a compromise. Therefore, it is quite a bit larger than what is needed in cruise in order to keep losses at low speed low. At low flight speed and full throttle the engine needs much more air than what is flowing into the inlet without the engine actively sucking air in. The flow lines converge from a much larger capture area when closing in on the inlet face and the stagnation point lies on the outer edge of the inlet lip.

Watch what happens when an airliner engine spools up on a rainy day, with puddles on the ground. When the engine reaches full speed, it starts to suck up even the water in the puddles below the intake! Some streamlines even come from behind, wrap around the inlet lip and get sucked in. With water droplets in them, they are very visible indeed.

At high speed, the capture area is much smaller than the inlet face. Only the central streamline stays straight, all others diverge away from that central streamline and now the stagnation point is on the inner edge of the inlet lip. Streamlines bordering the capture area flow around the lip and along the outside of the nacelle. This divergence of the streamlines is caused by the pressure increase ahead of the inlet, when the air is slowed down and exchanges kinetic for static energy. This even happens without friction losses, so the most efficient compression of an inlet happens ahead of it (in subsonic flow - supersonic speed removes that luxury).

The air speed at the compressor face is fairly constant at the same throttle setting, regardless of flight speed. Therefore, the pressure at the compressor face is lower than ambient at low flight speed (because air had to be accelerated) and higher at high flight speed.


What would be a technical or slang term for 'in the air'?

She kept the Squadron Leader updated as much as she needed to, but she
preferred to keep comms chatter to a minimum when she was...

Military-related terms:

...on patrol
...on station
...on a sortie
...on a shout [British English, specifically used for search and rescue]
...on recce/on recon [British and American English, respectively]

General terms:

...in the air
...airborne
...at the controls
...flying
...in flight
...on a mission
...doing (her) rounds
...aloft
...wheels up

There might be other, more technical terms in use in the military for specific operations or missions but I have no experience there.


Which trigonometric algorithm does an FMS use to determine distance between waypoints?

Short answer

Aeronautical data (fixes, waypoints, navaids, instrument procedures) are delivered to aircraft operators and avionics manufacturers referenced to the WGS-84 ellipsoid.

To make is simple the ellipsoid is the volume enclosed by the revolution of an ellipse which best approximates the shape of the Earth, generally in a given region only. WGS ellipsoid is a global one which approximates the whole Earth shape.

FAA provides rules for designing procedures, and algorithms to use to compute various elements, including the distance between two fixes and their relative azimuths. This is described in Order 8260.54 The United States Standard for Area Navigation (RNAV), Appendix 2. TERPS Standard Formulas for Geodetic Calculations:

  1.0 Purpose

  The ellipsoidal formulas contained in this document must be used in
  determining  RNAV flight path (GPS, RNP, WAAS, LAAS) fixes,
  courses, and distance between fixes. Notes: Algorithms and methods
  are described for calculating geodetic locations (latitudes and
  longitudes) on the World Geodetic System of 1984 (WGS-84)
  ellipsoid, resulting from intersections of geodesic and non-geodesic
  paths. These algorithms utilize existing  distance and azimuth
  calculation methods to compute intersections and tangent points
  needed for area navigation procedure construction. The methods apply
  corrections to  an initial spherical approximation until the error is
  less than the maximum allowable error, as specified by the user.

[...]

  3.4 Direct and Inverse Algorithms.

  The Direct and Inverse cases utilize formulae from T. Vincenty’s,
  Survey Review XXIII, No. 176, April 1975: Direct and Inverse Solutions
  of Geodesics on the Ellipsoid with Application of Nested Equations.

FMS use ellipsoid geometry to compute distances and angles, in order to match aeronautical data.

A visible consequence is that, except for meridians and equator, prlongating a geodesic on an ellipsoid doesn't draw a closed curve, as if it were a great circle:

Detailed answer: Need for WGS-84

New modes of navigation have emerged with a significantly better accuracy than using VOR-DME and inertial:

RNAV (area navigation) generally uses GNSS (global navigation satellite system, one GNSS being the US GPS),
RNP (required navigation performance),
and more generally performance-based navigation (PBN).

At the same time these new direct modes of navigation (compared to a navaid-to-navaid paths) can define paths extending to thousands of NM, and commonly crossing different geodetic reference systems where latitude, longitude, height and vertical can have significantly different values.

As an illustration, the measure of "height" used to be referenced to local MSL (mean sea level):

(source)

But a GPS receiver, which is now the main instrument to locate a point, can only provide the height above an ellipsoidal simplified Earth model. Latest receivers also provide the height above the simplified sea level model (geoid), but only as the result of a transformation of the ellipsoidal height, etc.

(source)

As visible above, the direction of the local vertical is impacted by the transformation, creating another problem for airborne vehicles navigation.

This can quickly become a nightmare with differences for the same point up to 100m depending on the reference used:

For these reasons, it appeared very early that all elements involved in mapping, navigation and ATC must use the same datum, in all countries. ICAO has selected WGS-84.

ICAO Doc9674:

  The Council [...] on 28 February 1994, adopted Amendment 28 to Annex 15,
  introducing the provisions concerning the promulgation of WGS-84-related
  geographical coordinates. [...]

WGS-84 on Wikipedia:

  The WGS 84 datum surface is an oblate spheroid (ellipsoid) with major
  (equatorial) radius a = 6378137 m at the equator and flattening f =
  1/298.257223563. The polar semi-minor axis b then equals a times
  (1−f), or 6356752.3142 m.

Current country compliance with ICAO selected datum: See Jeppesen WGS-84 Status Report.

Aeronautical databases

FMS uses aeronautical data (fixes, procedures) in the ARINC 424 format, where legs are WGS-84 paths.

Processing of aeronautical data

I've had difficulty to get the exact authoritative document making mandatory the use of ellipsoid geometry in a FMS, however, from FAA Order 8260.52 related to RNP, FMS are part of the so called GPN means which are referenced to WGS-84:

  Geographic Positioning Navigation (GPN).

  Navigation based on geodetic
  calculation of geographic position referenced to the WGS-84 ellipsoid.
  Global positioning system (GPS), wide area augentation system  (WAAS),
  local area augmentation system (LAAS), flight management system (FMS),
  RNP, and area navigation (RNAV) are examples of GPN.

When calculating distances between fixes, or angles, a FMS computes geodesics which are shortest paths between fixes. On a sphere this would be a great circle. On an ellipsoid this has to be adjusted, Vincenty's formulas are one of the methods that can be used for approximation.

Additional details on how geodesic calculations are done can be found in FAA Order 8260.58 related to Performance Based Navigation.


What is the process to get a simulator FAA certified for IFR training?

The FAA Advisory Circular 61-136 contains the guidance for Aviation Training Devices, including the BATD's.

The AC states that as long as the system has been FAA approved by the manufacturer (and in your case you say that it "meets the FAA requirements"), that no specific approval is required for training conducted under 14 CFR 61.  For use under 14 CFR 141 however, you would need specific FAA approval (see below).

14 CFR 61 Approval

You must simply follow the conditions specified in the AC:

  5. APPROVAL OF BATD FOR USE UNDER PART 61. To be approved for use for pilot   training and certification under part 61, a BATD should:

  a. Be capable of providing procedural training in all elements for
  which it is to be used.  Those elements should be specified in an
  acceptable training curriculum or as specifically  authorized by the
  FAA and meet the description and suggested criteria outlined in this
  appendix.

  b. Have the following documents available for inspection by the
  student and instructor:

  The list of ATD components as required by paragraph 3c,
  A copy of AFS-800’s letter of approval and authorized use of the ATD, and
  A copy of the QAG for the ATD being used.

  c. Successfully pass the start-up self-test described in paragraph
  8c(2). If the device is being used in a course of training for a pilot
  certificate or rating, a person authorized by the FAA to provide
  ground or flight instruction should observe this test. After the ATD
  self-test is complete, no other software of any kind may be started on
  the computer running the ATD software.

  d. Remain in the approved configuration during the training session.
  Authorized ATD  instruction may not proceed after a malfunction of the
  ATD system has occurred. The operator  must correct the ATD
  malfunction and repeat the start-up test described in paragraph c of
  this section before resuming authorized instruction. In addition, a
  BATD may be used in a training curriculum that provides for:

  A similar scope and content of a syllabus that is used under part 141;
  Instructional materials for flight events;
  A means of showing progress, such as an outline of stage (phase) checks and criterion  levels of performance; and
  The authorized use as approved in the AFS-800 letter of approval.

14 CFR 141 Approval

141 Approval is almost the same, but must be approved by the school's POI (principle operations inspector):

  6. APPROVAL OF BATD FOR USE UNDER PART 141. Local FSDO may approve  BATDs as part of an overall part 141 curriculum approval and
  certification process. Pilot schools that want to use a BATD as part
  of their training curriculum must notify their principal operations
  inspector (POI). The POI is responsible for approving how the BATD is
  to be used in the certificate holder’s part 141 curriculum. To be
  approved for use under part 141, a BATD should:

  a. Be capable of providing training in all elements in which it will
  be used, as specified in the syllabus, and meet the description and
  suggested criteria outlined in this appendix.     b. Have the
  following documents available for inspection by the student and
  instructor:

  The list of ATD components required in paragraph 3c,
  A copy of AFS-800’s letter of approval and authorized use of the ATD, and
  A copy of the QAG for the ATD being used.

  c. Successfully pass the start-up self-test described in paragraph 8c
  of this appendix. A  person authorized by the FAA to provide ground or
  flight instruction should observe this test. After the ATD self-test
  is complete, no other software of any kind may be started on the
  computer running the ATD software.

  d. Remain in the approved configuration during the training session.
  Authorized ATD  instruction may not proceed after a malfunction of the
  ATD system has occurred. The operator  must correct the ATD
  malfunction and repeat the start-up test described in paragraph c of
  this section before resuming authorized instruction.

  e. Be used in an integrated ground and flight training curriculum
  which provides for:

  The scope and content of a curriculum in compliance with part 141,
  The authorized use as approved in the AFS-800 letter of approval,
  Instructional materials for flight events, and
  An outline of stage (phase) checks and criterion levels of performance.


How did ATC procedures and airspace structure change after San Diego PSA collision?

The recommendations from the NTSB report are:

  Implement a Terminal Radar Service Area (TRSA) at Lindbergh Airpot, San Diego, CA
  Review procedures at all airports which are used regularly by air carrier and general aviation aircraft to determine which other areas require either a terminal control area or a terminal control radar service area and establish the appropriate one.
  Use visual separation in terminal radar service areas only when a pilot requests it, except for sequencing on the final approach with radar monitoring.
  Re-evaluate its policy with regard to the use of visual separation in other terminal areas.

The most direct change stemming from this accident is the establishment of a TRSA at Lindbergh on May 1, 1979. (It is now a class B area).

Also in 1979 the Lindbergh tower was equipped with some upgrades, including minimum safe altitude warning and conflict alert enhancements.

The other recommendations are fairly vague and I find no indication what, if any action was taken on them.
But as Gerry pointed out in comments, this accident put emphasis on the FAA's effort to create TCAS.  From the TCAS II V7.1 Intro booklet:

  In 1978, the collision between a light aircraft and an airliner over San Diego served to increase FAA's efforts to complete development of an effective collision avoidance system.

The see-and-avoid system is still very much in use. Visual approaches are still used. There really were no immediate systemic changes made in response to the accident. Mostly it was just airspace configuration around KSAN and enhancements to the radar system there. But, like every accident, the NTSB and FAA learned from it and took steps to improve safety. The FAA releases pamphlets appropriately titled, "Lessons Learned," about what can be taken from different types of accidents.


Flutter requires 3 factors to come together: flexibility of the structure that a control surface is attached to; the natural frequency of said structure; and an undamped moving mass attached to the structure with an internal CofG offset from the hinge point of the mass such that inertia helps magnify motion of the mass.  If you have an ultralight with a really floppy, flexible wing that can twist easily, with a heavy, unbalanced aileron, and you excite motion in the aileron, which excites sympathetic motion in the wing itself, you can probably get it to flutter at 40 mph.

I say undamped moving mass because a lot of jets with hydraulically operated control surfaces don't use mass balancing but depend on the damping of the hydraulic actuators, and if that isn't sufficient, dedicated flutter dampers that work like motorcycle steering dampers connecting the surface to the structure.

Anyway, ultralights and other lighter airplanes are able to avoid the factors I mentioned because, in designing it to hold up the airplane in the first place, the wing/stabilizer is inherently stiff enough, and/or the oscillating mass attached is light enough, combined with the lack of potential energy in the system at the low speeds they operate at, so it's not a problem.

You see lots of light airplanes (the Aeronca Champ for example) that operate up to 100 mph + without balanced surfaces because the structural stiffness of the strut/wire braced wing/tail and the light control surfaces makes it impossible for the control surface to excite sympathetic motion in the wing/stabilizer, making balancing unnecessary.


Which Inlet Barrier Filter (IBF) is used in Airbus H145?

The Airbus Options Catalogue for 2019 doesn't list an Inlet Barrier Filter for that aircraft.

The only IBF listed is for the AS350/H125 family


Does being cleared for a visual approach supersede speed instructions from ATC? (FAA)

The AIM 4-4-12 says that an approach clearance cancels a speed restriction, but ATC can explicitly restate the restriction if needed:

  Approach clearances supersede any prior speed adjustment assignments,
  and pilots are expected to make their own speed adjustments as
  necessary to complete the approach. However, under certain
  circumstances, it may be necessary for ATC to issue further speed
  adjustments after approach clearance is issued to maintain separation
  between successive arrivals. Under such circumstances, previously
  issued speed adjustments will be restated if that speed is to be
  maintained or additional speed adjustments are requested. Speed
  adjustments should not be assigned inside the final approach fix on
  final or a point 5 miles from the runway, whichever is closer to the
  runway

The ATC orders 5-7-1 give the controller guidance:

  c. At the time approach clearance is issued, previously issued speed
  adjustments must be restated if required.

  d. Approach clearances cancel any previously assigned speed
  adjustment. Pilots are expected to make their own speed adjustments to
  complete the approach unless the adjustments are restated


A bulk strip may be an Australian term, e.g. this airworthiness bulletin and this engine shop. I'd never heard of it before, but looking at those sites it seems to be something like a limited overhaul. The AB and the engine shop both list the steps and they're more or less the same: disassemble the engine, inspect all parts, replace any parts that need replacement, reassemble and test the engine.

I'm not an expert on maintenance by any means, but it looks to me like the difference between a bulk strip and a full overhaul is that the bulk strip is precautionary or diagnostic, as suggested by the machine shop site:

  Not all engines need a full overhaul. You may have had a prop-strike,
  or your LAME may have identified metal in the filter or a crack in the
  crankcase. The pilot may have noticed unusual running of the engine.

  We can ‘bulk-strip’ your engine for a full diagnosis and provide you
  with a report of your engine’s health:

Looking at it another way, an overhaul will replace a lot of parts whether they need it or not; a bulk strip may replace parts if they're worn or broken.


How does a pilot maintain stability for an unbalance loaded airplane?

Use the available trim (elevator, and rudder if installed), and then manage the left/right fuel tanks if they are not feeding evenly.  Use the autopilot if so equipped, even if it's just a single axis wing leveler.

With just 1 passenger, it is hardly out of balance tho. The POH has a Weight & Balance chart as seen here  How are the limits of the center of gravity chart established?, plotting front seat weight and fuel will show the plane to be well within limits.