Why are there so many ADS-B ground towers in western Colorado?

As GdD commented, the cluster you noticed is not near Denver, but Montrose, CO. The reason for this cluster is Wide Area Multilateration (WAM) with ADS-B. This technique uses many sensors distributed around an area to provide better coverage in areas with mountainous terrain that blocks a single radar or ADS-B station. Western Colorado is one such area that experiences delays when ATC does not have sufficient radar coverage to support operations in inclement weather. Montrose is one of the areas that the FAA is using to develop this technology. This "constellation" serves the following airports:

Gunnison-Crested Butte Regional (GUC)
Montrose Regional (MTJ)
Telluride Regional (TEX)
Durango-La Plata County (DRO)

See also this technical presentation about the WAM project, and the lease for the tower sites.

Also, somewhat related, see this NTSB safety recommendation regarding ADS-B coverage serving SAR needs after a crash near Montrose.


Yes, the plain wing area is also used for wing loading. How the value is calculaed depends on the method used. In all cases the center section and ailerons are included but the horizontal tail is excluded. Common is also the use of the projected area of the clean wing in the x-y-plane, because that is the area relevant for lift.

For airliners, the two most important methods are the Wimpress and the Airbus method (the Wimpress being used by Boeing). The difference is the triangles you get by extending the wing's leading and trailing edges forward into the fuselage for Wimpress versus connecting the points where the leading and trailing edges meet the fuselage on both sides by two straight lines for Airbus. This discussion on airliners.net lists a comparison of the wing areas you get with both methods for a range of models.

Wing area methods in comparison. The shaded are is covered by the fuselage and determined differently; creating different areas for the same wing.

Note that the specifics of the method used is irrelevant for the purpose: This wing area serves as the reference area of most aerodynamic coefficients and either method is good enough for the purpose. Consistency is more important than precision here.

Both methods have been around for a while, so there was no change recently. But since both are used in parallel, there is no common standard.


What process do I follow to land a civilian aircraft on a military base?

Landing at a US military base isn't all that hard (I've landed at Ft. Drum before), you just have to get prior permission (PPR) (submitted at least 30 days in advance and confirmed within 24 hours according to 32 CFR 855.8), and need to have a "good reason" (as determined by them).

32 CFR 855, Table 1 (which is quite long) includes the purposes that are normally allowed.

You will be required to submit the following forms to the base commander (See the A/FD):

DD Form 2400 - Civil Aircraft Certificate of Insurance
DD Form 2401 - Civil Aircraft Landing Permit
DD Form 2402 - Civil Aircraft Hold Harmless Agreement

32 CFR 855 contains the regulations pertaining to US Air Force airfields (and the rules are similar for each branch).

855.1 - Policy includes:

  (1) Normally, landing permits will be issued only for civil aircraft
  operating in support of official Government business. Other types of
  use may be authorized if justified by exceptional circumstances.
  Access will be granted on an equitable basis.

  ...

  (3) Any aircraft operator with an inflight emergency may land at any
  Air Force airfield without prior authorization. An inflight emergency
  is defined as a situation that makes continued flight hazardous.

855.5 - Responsibilities and authorities. includes:

  (6) Will not authorize use of Air Force airfields:

  (i) In competition with civil airports by providing services or
  facilities that are already available in the private sector.

  Note: Use to conduct business with or for the US Government is not
  considered as competition with civil airports.

  (ii) Solely for the convenience of passengers or aircraft operator.

  (iii) Solely for transient aircraft servicing.

  (iv) By civil aircraft that do not meet US Department of
  Transportation operating and airworthiness standards.

  (v) That selectively promotes, benefits, or favors a specific
  commercial venture unless equitable consideration is available to all
  potential users in like circumstances.

  (vi) For unsolicited proposals in procuring Government business or
  contracts.

  (vii) Solely for customs-handling purposes.

  (viii) When the air traffic control tower and base operations are
  closed or when a runway is restricted from use by all aircraft.


Is there a database of European surveillance radar installations?

Meanwhile i found an answer to my question. Location data of radar stations is for most countries provided in the AIP ENR chapter 1.6 "ATS Surveillance Services and Procedures". Some countries do not provide the coordinates of radar location, but only a coverage map. European AIP may be accessed through Eurocontrols EAD service.


What causes Mach No. to increase with altitude at a constant cost index?

Cost index is a function of Time Cost/Fuel Cost and is more related to True Air Speed than Mach Speed since Mach Speed varies with altitude.

At FL300 M.85 equals 501 knots but at FL400 M.85 is only 487 knots. In order to maintain 501 knots at FL400 you need to increase your Mach speed to M.87


How can I see the revision history of a particular FAR?

Changes to federal aviation regulations are listed on the FAA’s Regulatory & Guidance Library (RGL) at http://rgl.faa.gov/:

From the home page, click on the database titled "Code of Federal Regulations"
On the left, in the navigation tree, select one of the branches under "Historical CFR" (for example, "By Part")
On the right, expand the items leading to the regulation that you are looking for (in this case Part 61)
Scroll down to the regulation that you are looking for (61.51) and it will list the original version and all of the revisions:

Each revision is a link which takes you to the regulation as of that version, with links to the NPRM's and dockets so that you can see what has been changed!


When calculating takeoff performance why include airport elevation in pressure altitude?

If the altimeter says the station pressure is 29.92" sea level, but I am at 3000', then the airplane still thinks it's at sea level when it comes to performance. Is that wrong?

Although the station pressure may be reported as 29.92", that does not mean that a barometer there will show that as the current pressure.  The reported value is the actual pressure, plus an extra amount that is calculated would occur if the recording station were lowered down to sea level.  Instead of actual pressure, you are setting the QNH pressure.

So sitting at a 3000' airport with the altimeter reading 29.92 does not mean the airplane thinks it's at sea level.  Certainly the altimeter doesn't think this, because it's reading 3000'.

You could use the actual pressure outside as an altitude-independent performance gauge, but you don't normally have that value (and ATC isn't going to radio it to you).


How does the attitude and heading reference (AHRS) work on Boeing 737 aircraft?

The 737 does not have a separate AHRS. Those functions are simply outputs from the two IRS's.

(Source) 737 IRS panel.

ATT (attitude) mode selects the AHRS-only output of the IRS.


Semi-circular rule for choosing a FL: Risk of head on collision with borderline headings (179, 359)?

The adoption of semi circular rules is not meant to prevent collisions on its own. Rather, it is one of several safety nets contributing to a safe and orderly flow of air traffic. In uncontrolled airspace, normal rules of the air apply, for example, two aircraft meeting head on must both alter their heading to the right in order to both pass with the other aircraft on the left.

The actual "risk of collision" you are asking about, for someone flying in uncontrolled airspace, is incredibly small. One reason is that the amount of traffic in uncontrolled airspace is typically quite low, since authorities will most likely establish air traffic control for congested areas. Even in uncontrolled airspace, flight information service is provided in order to - among other things - prevent collisions. And collision avoidance systems, such as TCAS, will also help. Crucially, all aircraft have windows, and the pilots are trained to look out in order to see potential conflicting aircraft and react in time.


What is the purpose of the fuel shutoff valve?

It's both a maintenance and safety feature.

You need a way to cut off fuel flow to the engine compartment, either to work on the engine, or because of a fire at the engine, or because you are doing a forced landing and it helps reduce the risk of your entire fuel contents seeping onto your hot engine if you bend things a bit putting it down and a fuel line gets broken.

So you will always have a shutoff valve, and it's always somewhere upstream of the firewall.


What is the meaning of "regular pitch" when applied to a propeller?

Ill assume you are asking the context of fixed pitch propellers. In which case "regular pitch" is either the standard pitch for the airframe in question or some mid range pitch to deliver average performance. There are usually various propeller options for a given aircraft:

  There are two types of fixed-pitch propellers: climb and cruise.
  Whether the airplane has a climb or cruise propeller installed depends
  upon its intended use. The climb propeller has a lower pitch,
  therefore less drag. Less drag results in higher rpm and more
  horsepower capability, which increases performance during takeoffs and
  climbs, but decreases performance during cruising flight.

You can read more here.


How can cargo be jettisoned from a C-124 in flight?

The C-124 had a opening in the rear, through which cargo (or paratroopers) could be dropped. From globalsecurity.org:

  The C-124 was also used for airdrops. ... In the back of the plane, the underneath of the airplane had elevator doors that opened up and the crew could drop cargo out, or paratroopers could jump out.

Here is an image of the elevator doors in open position

The rear elevator opening of the Douglas C-124 Globemaster II where an elevator platform could be lowered or raised for bulk cargo operations (often the platform was removed so an interior hoist could directly move cargo) — photo by Joseph May; image from travelforaircraft.wordpress.com

Here is a C-124 using that door for an airdrop, presumably in Antarctica (I've put the image as I came across; I'm pretty sure that it's rotated)

Image from antarctica.recollect.co.nz

The crew must've used the rear door rather than the front one for jettisoning the nuclear weapon. The text of the official report reads:

  The C-124 aircraft was en route from Dover AFB, Delaware, when
  a loss of power from the number one and number two engines was experienced.
  Maximum power was applied to the remaining engines, but level flight could not be maintained. At this point, the decision was made to jettison cargo in the interest of safety of the crew and aircraft. Three weapons and one nuclear capsule were aboard the aircraft, and nuclear components had not been installed in the weapons. The first weapon was jettisoned at 4,500 feet altitude. The second weapon was jettisoned at approximately 2,500 feet altitude.

With the difficulties the crew was experiencing in keeping the aircraft level, it would only be logical that the rear doors were used, not the front.


How many radio transmissions per hour occur on a given frequency over Europe and North Atlantic?

It helps to check prior research in that field, for example, VOCALISE: Assessing the impact of data link technology on the R/T channel (2005).

  Quantitative aspects of pilot-controller communication are addressed in two en-route air traffic control studies: the VOCALISE study in a real operational environment (Graglia and al., 2005), and the EEC study in a simulation environment (Hering, 2001).

  The VOCALISE study shows that on average 324 speech acts between controllers and pilots were recorded per hour in an en-route sector, or about 5 per minute.

(Source: Eurocontrol)

So for the en-route portion, a single sector/frequency deals with about 5 transmissions per minute. Note that some of the transmissions would fall under miscommunication, such as:

  Incorrect read-backs
  Call-sign confusions
  Initiation failure
  Understanding failure
  Memory failure
  Information failure
  Omissions
  Redundancies

An example breakdown:

  [Out] of the incorrect read-backs, 30% are simple "say again" requests, and another 30% requests for repetition or confirmation of route information.

So that's another aspect to include in the simulation you'll be conducting.


Can paragliders in the US communicate with ATC?

Where noted, the information in this answer is from Advisory Circular 103-6, which was issued in 1983, but which apparently is not actually obsolete.

  Is it possible to get the equivalent of flight following or at least call up ATC to let them know you are there, if you are planning on flying at higher altitudes? I am used to doing this for a D airspace if I am flying only just over or near it if they are not busy.

It's certainly legal to call up ATC while you're flying an ultralight, whether it's Part 103 or not. The relevant FCC regulation, 47 CFR § 87.18(b), says that aircraft are "licensed by rule and [do] not need an individual license," and ultralights are aircraft, so an airband radio on an ultralight counts as being licensed.

Advisory Circular 103-6 also recommends that ultralight pilots contact ATC using the ordinary radio frequencies (but I believe it was written when all airband radio users needed individual licenses).

I don't know whether or not ATC gives flight following to ultralights. Advisory Circular 103-6 says that separation services "will not be available to ultralight pilots." But there's no harm in asking.

  If so, what would the phrasing of that sound like when you don't have a callsign?

There's the tricky bit.

The regulation governing this is 47 CFR § 87.107(a), which states that you should identify using one of the following four options: your "aircraft radio station call sign"; the aircraft type and registration number; your radiotelephony designator and flight number; or a temporary identifier for "organized flying activity."

However, if you're flying a Part 103 ultralight, then in all likelihood, you don't have any of those.

Advisory Circular 103-6 states that "ultralight operators should state the word 'ultralight' followed by the call letters assigned by the F.C.C. on your radio license, i.e., 'Ultralight 12593U.'" Assuming you don't have a radio license, it seems like the best you can to is to simply use the word "ultralight" as your call sign.

  14 CFR 103.17 says that I require prior authorization to enter class B, C or D airspace. What does this look like? Can I take a handheld radio and ask for permission on the tower frequency? Or is this something I'd need to get through written permission from a FSDO or the tower directly?

Advisory Circular 103-6 says, "Requests for authorization to operate an ultralight vehicle into [controlled airspace] should be made by writing, telephoning, or visiting the air traffic control facility having jurisdiction over the airspace in which you wish to operate. Requests for such authorization via air traffic control radio communication frequencies will normally not be accepted, since it may interfere with the separation of aircraft."

That said, I'm not aware of any special legal meaning of the phrase "prior authorization." So on the off chance that ATC does tell you that you're allowed to enter the airspace, presumably you can do it.


What would be the minimum number of engines required to climb in a 747?

@Michael Hall said it best, in the first sentence of item 1 of his answer:

  There are simply too many variables for a definitive answer.

Here are two extremes to illustrate the range of answers insofar as altitude is concerned:

Let's say you have a 747 at it's optimum altitude in cruise with all four engines operating, say 37,000 just for the heck of it. Now let's say you lose one engine. Can you now climb on three engines? No, in fact you won't even be able to keep the altitude you have. You will start drifting down.

Now let's say that same 747 with the same load (actually heavier because it would still have the fuel on board that it used to get to its 37,000 foot cruise) lost an engine while on the takeoff roll but after V1. Will it climb? Yes, even with the drag from the gear and takeoff flaps you will be able to lift off the runway and climb.

But back to the one-engine scenario. My gut level feeling is that any 747, if carrying no passengers or cargo and only, say, 30,000 lbs of fuel and down low (5,000 ft?) and in a clean configuration could eke out a little climb. Can't prove it though.

But start adding weight or drag and the answer would change. The first model to not be able to do it with weight and drag being added would be the 747-100. The first -100s I flew had a max takeoff weight of 735,000 lbs as I remember. The next model to fail would be the -200. 825,000 lbs was the highest max takeoff for the -200s I flew. The highest max takeoff that I have for a -400 on the DOS weight & balance software I wrote was 910,000 lbs.

The biggest difference performance-wise is due to engine size. The more power the one engine has, the more it can keep aloft.

And there are other variables. What was the nature of the failures of the three engines? Are they windmilling or seized? Even whether the remaining engine is an inboard engine (2 or 3) or an outboard engine (1 or 4) is a factor. When it comes to performance, even how many insects are splattered against the leading engine of the wing can make a difference.


Do transatlantic flight plans have alternates routes?

Each airborne flight has only one flightplan, which was submitted for that particular flight.
The routing is embedded into that flightplan and only that one routing is valid for that flight.

In case the routing is no longer available for the next flight due to airspace closure via NOTAM or airways being restricted by time of flight / day of flight, another routing will be used for that flight and submitted in the flightplan.

In case the routing needs to be changed for an already airborne flight, a new IFR clearance is read to the crew en-route, which alters the existing flightplan.

Alternate routings are usually managed by the airline's dispatch / planning centre and the best routing for a specific flight is created by the dispatchers, taking into account weather, NOTAMS, restrictions and many other factors.

En-route changes to a flightplan are made by ATC units and their data processing centres, if an impromptu change needs to be made due to airspace closures or other restrictions coming into effect which were unforseen.


How can I determine the amount of trim drag?

As I mentioned in my comments. You could test this empirically with the experiment described there.  If you find the additional ballast improved the glide performance of the craft, is there an aftermarket STC kit available which installs new ballast tanks in a more optimum position for a more neutral cruise trim?

I am a little concerned with the idea of continuing to move the CG aft of its current position in order to optimize the performance at the expense of. Asking the craft less stable about the lateral axis.  No increase in performance is worth your life.


What is the difference between ICAO and non-ICAO flight address?

The use of the non-ICAO flight address field is described in the very same document, on table 2-11, page 53 of the PDF:

  AA field holds another kind of address for the transmitting
  ADS-B Participant: a self-assigned "anonymous" address, a
  ground vehicle address, or a surface obstruction address.

Ground vehicles and surface or tethered obstructions want to participate in ADS-B, but they don't have ICAO aircraft addresses, so they have to have their own addresses. Since these addresses aren't centrally assigned, the CF field is used to keep them distinct: otherwise, you could have a vehicle address that conflicts with an ICAO aircraft address.

The different kinds of addresses are further described in section 2.2.5.1.1 (p 172 of the PDF).


Must Part 91 pilots comply with runway departures marked as NA?

Other than flying a published SID or ODP with charted takeoff minimums, there are no other takeoff minimum requirements for pilots operating under Part 91.

If a Part 91 pilot receives and accepts a published departure procedure from ATC then they must comply with any minimums published on the procedure.

For example, some SID's may show takeoff minimums with a runway listed as "NA" (the Aspen Seven Departure as KASE lists "Rwy 15: NA - Terrain"). If you accepted this SID then you wouldn't be able to use runway 15 even operating under Part 91.

But just because you can doesn't mean you should. Every pilot flying Part 91 should have a set of personal minimums.

Just a pilot interpreting the regulations though, not a lawyer :)


What powers the air required for pneumatic brakes in aircraft?

For a medium size turboprop, the F-27: two separate compressors, driven by the turboprop engines.
From this article

Fairchild’s F-27 is the first American-made plane to use a complete pneumatic system to operate landing gear, wheel brakes, nose wheel steering, propeller brakes, and passenger door operation. It also has an emergency air supply that will lower the landing gears and operate the brakes.
Compressed air for the system is supplied by two 2-cfm, 3300-psi compressors located in each of the engine nacelles. The compressors are driven through a gearbox by Rolls Royce Dart engines, which power the aircraft. They carry their own individual dehydration and filtration equipment to supply clean, dry air at a pressure of 3300 psi

Most present day airliners use the hydraulic system for the landing gear, including wheel braking. For instance on the B737:

The normal brake system and autobrakes are powered by hydraulic system B. If brake pressure drops below 1500psi, hydraulic system A automatically provides alternate brakes which are manual only (ie no autobrake) and the brake pressure returns to 3000psi.

The hydraulic systems are each powered by an Engine Driven Pump and an Electric Motor Driven Pump.


Will a portable ADS-B unit, like Stratus, meet the requirements for my aircraft to be ADS-B equipped by the 2020 mandate?

The short version is no the Stratus will not meet the requirements, and for several reasons.

The final rule requires ADS-B OUT (and the Stratus is only ADS-B IN) that meets particular TSO requirements (see below), and portable units will not.

The FAA has an ADS-B FAQ on their website which has a lot of great ADS-B information.

The minimum equipment required to meet the mandate is addressed by:

  What equipment is required by the new rule?

  The rule specifies ADS-B
  Out equipment compliant with either Technical Standard Order
  (TSO)-C154c (Universal Access Transceiver) or TSO-C166b (1090 ES).
  However, to operate in Class A airspace, aircraft are required to
  equip with avionics certified to TSO-C166b.

The FAQ also specifically addresses the question of portable units and says that they will not be allowed:

  Will the FAA allow portable/handheld units, or will they have to be panel mounts only?

  Installed transponders and GPS units must meet certification
  standards. Handheld devices and displays that serve only for
  situational awareness have more flexibility and are not certified
  installations. In order to comply with 14 CFR § 91.225 and 91.227
  aircraft intended to fly in ADS-B airspace must have installed and
  certified equipment. Portable installations are not compliant to the
  rule and would only be usable for receiving FIS-B services for
  situational awareness. The FAA is in the early stages of investigating
  a portable device for glider aircraft.


What is the slowest fixed-wing airplane?

The Gossamer Albatross is a human-powered plane with a top speed of 29 km/h (18mph).

It was used to cross the English Channel and seems to meet the criteria of the question.


The Kawasaki T-4 actually has three hardpoints that can carry weapons
: one underfuselage and two wingpoints (also confirmed here). The possible armament includes gun pods, long-range anti-ship missiles, air-to-air missiles, free-fall or retarded bombs and pods with 70 mm unguided rockets. Hence no way it could be said it cannot be armed.

This aircraft seems more for training but can be used in light attacks.


What happens when you call 866-GA-SECURE in the US?

OK, I did a little digging and here's what I can definitively tell you:

1-866-GA-SECURE is a joint venture between AOPA's "Airport Watch" program and the TSA.
The hotline is staffed by federal officials and can be used for reporting suspicious or unauthorized activity - e.g. the theft of an aircraft, someone prowling around on the ramp after hours, etc.
The folks answering the hotline will be able to contact local law enforcement (and being that they're federal officers making the call instead of Joe Pilot, they may get a quicker response than you would), but police dispatch isn't their primary function.

The TSA's own guidance on this hotline indicates that it shouldn't be your first resort -- they would prefer that you contact:

Airport management/operations/FBOs
Particularly at fields that are attended 24/7, and those with security or police presence, calling the folks on the field will often give the fastest response, and they should be your first call.
The TSA Hotline (1-866-GA-SECURE)
For fields which are not attended / don't have a security or police presence, this can be an effective way of getting law enforcement to the field quickly.
911 or other local law enforcement emergency numbers
In situations with immediate and potentially dangerous consequences, or ongoing criminal activity (breaking into aircraft, bypassing gate locks, etc.) calling local law enforcement's emergency number / 911 is The Right Thing To Do.

In all cases you can follow up with a call to the TSA hotline to confirm they're aware of the incident.  Whether on an initial call with an ongoing situation or a follow-up the hotline folks will want the basic 911 information (Who you are, Where you are, and What your emergency/situation is). Obviously depending on the situation they may ask for additional details - e.g. if you're reporting that a plane was stolen it would be very helpful if you could provide the registration number.

AOPA's GA Security course covers a bit more of what you may be asked for / about, and the kind of things you should be looking for when informing any of the above authorities of suspicious activity.

Who responds to your hotline call and how quickly they respond is less definitive: It will vary depending on where you are and the local resources available.  A grass strip many miles away from the closest police presence at 3 AM will obviously have a longer response time than a 24x7 attended field with a police presence on the field, no matter who you call.

Typically the first response will be airport personnel (if the field is attended) or local law enforcement (and obviously that will be the case if you're calling the airport's management/operations office or the local police directly).  Whether or not federal authorities get involved in the response would likely depend on what you're reporting.


The NOAA National Weather Service Glossary defines relative wind in a way that might help you make sense of this:

  Relative Wind: The wind with reference to a moving point. Sometimes called APPARENT WIND.

From the diagram in the linked question, you can see that the relative wind is a vector opposite the propeller's 0 degree angle of attack. Simplified, this relative wind is the speed the wind would appear to flow if the air was moving, instead of the propeller. But since the propeller is moving and not the air, we call it relative wind: relative to the propeller, the air is flowing over it because the propeller is moving.

However, I'm sensing from your question that you might think there is only one relative wind vector, and that is the one parallel and opposite direction to the 0 degree angle attack of the main wings.  However, the as you can see from the definition, any moving point is going to have relative wind!

Remember that relative wind is just the wind in reference to a moving point. So once the airplane is in forward motion, even though the air in the propeller's plane of rotation is no longer still, the relative wind that the propeller "feels" is still coming from the same direction as before, but the magnitude may be modified by the change in the actual speed of the air in the propeller's plane of rotation. Then to get the strength of the relative wind on the propeller, you'd need to add the wind vector caused by the forward motion.

At the risk of over-explaining, remember it's relative wind. Rather than the air blowing (creating wind), the object is moving, so the wind is relative to the moving object.


What is the fuel mass flow rate at stationary full power for the CFM56 5C2/3C1 engines?

If you know the TSFC at conditions above I can calculate the fuel mass flow and would resolve the issue.

From this page, the CFM56-5C2 used on the A340-211/-311 delivers 31,200 lbf and its SFC is 0.320 lb/lbf hr. The cruise thrust and SFC are 6,910 and 0.545 respectively.


How does Chicago O'Hare's tower sequence aircraft at peak capacity?

Chicago runs simultaneous triple parallel approaches. And as soon as an aircraft clears the runway, another one is allowed to cross the threshold.

Chicago Tower actually does not do the bulk of the sequencing of aircraft. Chicago TRACON actually sequences the aircraft before they are handed to the Tower. Even before that, Chicago ARTCC begins to sequence inbound aircraft. Similarly, aircraft are handed to departure (TRACON) almost immediately after taking off. Departure procedures are optimized for safety and efficiency.

This figure breaks down runway usage percentage for arrivals and departures in April 2015 (7am - 10pm traffic)(source paper). It highlights the common westbound landing flow with triple parallel runways. You can also see two diverging runways used for the bulk of departures, with sporadic usage of others.

Note that this is all after an airport runway overhaul. Consider that 2014 saw almost a 10% decrease in operations from the year 2005. Having talked to controllers that have put in time at Chicago Tower, it is as crazy to handle as humanly possible.


Did John Stringfellow ever build an aeroplane, powered by a steam engine, that really flew?

I was not able to discover articles of 1848, or even up to 5 years after, that give details about the 1848 flight of Stringfellow's model. However, I found 3 first hand articles, published on July 3, 24 and Oct. 9, 1868, which say that, at an exhibition which took place starting with June 25, 1868, at the Crystal Palace in London, John Stringfellow exhibited two engines. For the larger one, that generated, when started, a little more than 1 HP, he took a prize of 100 pounds. The smaller motor was installed on a working plane which apparently flew but the description is vague being unclear whether the author talks about an event that happened in 1868 or he refers to previous flights, like the one of 1848. Anyway, the conclusion was that despite taking the prize (for the larger standalone engine) it was not clear whether that motor would serve for any practical purposes in aeronautics.
From the numerical values furnished by the commission that awarded the prize, it results that Stringfellow's motor needed:
$150 ft * 3 in^2 = 88.5 liters$ of steam at $80 lbf/in^2 = 5.4 atm$ per minute to generate 1.09 HP continuous power.
Nothing is said about the interval of time during which the boiler was able to maintain this considerable flow of steam. Another remark would be that the steam was expelled from the cylinder at 5.4 atm which means the engine had a very poor efficiency.
"The Aeronautical Society of Great Britain", The Mechanics' Magazine, July 3, 1868, col. 2-3, p. 3.

THE AERONAUTICAL SOCIETY OF GREAT BRITAIN. ...
We have said that there are a few exhibits which are a step in advance
of the rest at the Crystal Palace. Amongst the rest may be noticed a
working model of an aerial steam carriage, by Mr. J. Stringfellow, the
whole, including engine, boiler, water and fuel, weighing about 12
lb.; cylinder, 1 3-16ths inch diameter; 2-inch stroke; works two
propellers, 21 in. diameter, about 600 revolutions per minute; gets up
steam of 100 lb. pressure in five minutes. ...

"The Aeronautical Society Late Exhibition", English Mechanic and Mirror of Science, July 24, 1868, col. 3, p. 378.

THE AERONAUTICAL SOCIETY'S LATE EXHIBITION.
THOSE who predicted that the exhibition of the Aeronautical Society at
the Crystal Palace would prove a failure may, in part be said to have
been true prophets; but the exhibition was not all a failure — far
from it: enough, we think, was given in evidence to cause at least one
section of the members to be of good heart. True, the expected
demonstration of the possibility of flying was not made, and the
rewards offered for flying have not been gained. The flying man put in
no appearance with bis wings, and the only model of this class which
actually worked was the ingenious steam-propelled machine of Mr.
Stringfellow, which, running along a a wire, has enabled our facetious
contemporary, "Punch," to change the inventor's name to Wirefellow,
and which elicited the remark from sundry spectators of a certain
class that "he was wiring into it."

"The Aeronautical Exhibition", The Mechanics Magazine, October 9, 1868, pp. 282-284.

THE AERONAUTICAL EXHIBITION.
IT will be fresh in the memory of our readers that the Aeronautical
Society of Great Britain held their first exhibition at the Crystal
Palace on the 25th of June last and ten following days. ...
The only engines, therefore, which competed for the prize were three,
— one by M. Camille Vert and two by Mr. J. Stringfellow. M. Vert's
engine was a small model of a steam engine, weighing 2 lb., for
propelling a hydrogen gas balloon. Mr. Stringfellow's engine No. 1 was
a light engine and boiler for aerial purposes; it was of 1-horse
power, and weighed 13 lb. No. 2 was a similar engine on a smaller
scale. M. Vert's engine was found to be too small to enable any
accurate test to be applied for ascertaining its power. The jurors
state that it appeared to keep up steam well in the repeated
demonstrations in propelling a model balloon in various directions
within the Crystal Palace building.
Mr. Stringfellow's engine No. 1, from its size and power, may be
considered something more than a mere model. The cylinder was 2 in. in
diameter, stroke 3 in., and it worked with a boiler pressure of 100
lb. per square inch, the engine making 300 revolutions per minute. The
time of getting up steam was noted; in three minutes after lighting
the fire, the pressure was 30 lb., in five minutes 50 lb., and in
seven minutes there was the full working pressure of 100 lb. When
started, the engine had a fair amount of duty to perform in driving
two four-bladed screw-propellers, 3 ft. in diameter, at 300
revolutions per minute.
In the jurors' report, the data for estimating the power are taken as
follows: — Area of piston, 3 in., pressure in cylinder 80 lb. per
square inch, length of stroke 3 in., velocity of piston 150 ft. per
minute, 3 x 80 x 150 = 36,000 foot pounds; this makes rather more than
1-horse power (which is reckoned as 33,000 foot pounds). The weight of
the engine and boiler was only 13 lb., and is probably the lightest
steam engine that has ever been constructed. The engine, boiler, car,
and propellers together, were afterwards weighed, but without water
and fuel, and were found to be 16 lb. The council of the Aeronautical
Society agreed that this engine, as a complete working machine, met
the condition of the Society's award for "the lightest engine in
proportion to its power from whatever source the power may be
derived." The prize of £100 was accordingly allotted to Mr.
Stringfellow. ...
The exhibition, however, proved that the advocates for aerial
locomotion by mechanical means have greatly increased in number, and
their designs for accomplishing this end were as varied as they were
ingenious. But still we have no practical result by which we can
measure the progress of aeronautics in this direction; we cannot say
we have even attained the first step in actual practice. The nearest
approach that was made to this long-desired condition of things was
the demonstration that by means of vertical screws a weight of 100 lb.
might be supported by a constant force of about 90,000 foot-pounds or
three-horse power. Then we have Mr. Stringfellow's engine of one-horse
power and weighing only 13 lb., which, taken in conjunction with the
vertical screws, would appear to indicate the direction in which
mechanical flight may be realized; and this is as far as we have got —
just on the borders of possibility. But we must bear in mind the
enormous expenditure of power the system of vertical screws requires,
and the very flimsy character of an engine and boiler sufficiently
powerful to work them, and sufficiently light to allow of their
working result, if, and when attained, being made available for
transit.
It practically comes to this, that Mr. Stringfellow carried off the
£100 prize for the lightest engine in proportion to its power, but of
what real service that engine will prove to the science of aeronautics
remains still to be seen.


Why do some military aircraft carry two datalink pods?

That pic is from "the Naval Air Warfare Center, Weapons Division (NAWCWD)"
So, testing and development.
Possible reasons (purely speculative):

Testing capability/performance from the 2 different wing stations.
Test/compare different software configs in each.
Ferry one to somewhere else.


What is the difference between VFR Flyways, Corridors and Transition Routes?

VFR Flyways

These are the most loosely defined, and can be found on a TAC (Terminal Area Chart) as shown below. They suggest general routes and altitudes near busy airspace to keep VFR traffic out of restrictive airspace. This is one answer to the question of how pilots know if they are inside controlled airspace or not.

VFR Corridors

A corridor is a section of airspace that has been cut out of more restrictive airspace, like Class B, to allow VFR traffic to transit without explicit clearance. There will often be suggested altitudes and frequencies to prevent conflicts. Below you can see that there is a hole in the KSAN class B from 3300 to 4700 ft AMSL.

VFR Transition Routes

These are also found on the TAC as shown below and are charted routes for VFR aircraft to fly through more restrictive airspace. They will require contacting ATC, but provide a route for pilots to quickly request and then fly to avoid having to take a longer route around the area.

See also: Special Flight Rules Areas

Sometimes the basic provisions above aren't enough and the FAA defines a Special Flight Rules Area (SFRA). This defines special procedures and requirements for operating in the area. An example is the Los Angeles area where pilots are allowed to fly through the Class B without contacting ATC as long as they follow certain requirements.


You could, if the aircraft is available for sale somewhere, and there are no other legal compliance problems. Paul Allen has a nice collection of military aircraft at his Flying Heritage Collection, and there are certainly quite a few other people with both flyable and unflyable military aircraft. There are also private companies which will let you try out their planes, such as Australian Jet Adventures

Here is a web site which tracks military planes in private ownership around the world:

http://www.warbirdalley.com/


There are a few ways rough throttle handling on a propeller airplane can get you into trouble:

Gyroscopic yaw and torque: a rotating prop creates yaw 90 degrees to its spin which are offset by control inputs (mainly rudder), throttling up or down requires changes to these control inputs. Quick changes require bigger changes, slower changes give a pilot more time and allows smoother transitions. This isn't that big a consideration on lower-powered aircraft but it is on high-performance aircraft. In the first case that comes to mind an inexperienced P-51 pilot rammed full throttle in on a go-around and it flipped the aircraft on its back. At low airspeed it's possible there wasn't enough control authority to manage the forces even if he had been prepared for them
Pitch changes: most aircraft will have a pitch change when the throttle is increased or decreased, again quick changes require coarser changes in controls while slower changes mean smoother and better controlled inputs. Again more applicable to higher performance aircraft
Engine and carburetor: The engines in most light propeller-driven airplanes represent the pinnacle of 1950's technology. Fuel mixture, priming, and throttle control are all completely manual - there are no electronic systems to help smooth things out during throttle changes. Many airplane engine carburetors do not have an accelerator pump to shoot extra fuel to prevent the engine stalling during a quick throttle up. Given that an engine stall when airborne is a life-threatening emergency it's in your interest to make smooth, controlled changes

Although not usually a safety issue wear and tear is also a consideration. Smooth, gentle changes are better for the levers, plungers, and cables in the engine control system. Less wear and tear means better reliability and less costs.


How does the LIP package which is standard on the A320NEO enable to approach at a slower speed?

On first impressions, all of those (except the nacelle strake and the fillet) seem to modify the high lift system (slats/flaps), presumably to optimise air flow in the gaps between slat and main wing or main wing and flaps. This is probably done to increase the maximum attainable angle of attack or lift coefficient, which will reduce stall speed and thus allow a lower approach speed.

The nacelle strakes normally are used to optimise flow around the engine nacelle at high angles of attack, either to prevent premature wing stall around the nacelle or to at least improve aircraft handling qualities by preventing localised flow separation at the nacelle. Adding another strake on the other side will, I imagine, again allow a slightly higher angle of attack to be sustained and thus will lower the permitted approach speed.

The wing body fairing modification most probably, too, will allow a more optimal local air flow.

All of this is my speculation based on the list of changes in the question; I don’t have additional knowledge on this particular aircraft performance package.


What do you squawk when multiple conditions apply?

There is a trail of canceled AC's here that all say "only available within the FAA network" that might cover the topic if you can get ahold of them.

I found a brief mentions of it in this AC relating to ADS-B and its integration with transponders.

  Operational procedures regarding the transmission of the generic
  emergency code (i.e., 7700) in cases when the flightcrew actually
  selected a discrete emergency code (e.g., 7500, 7600);

According to that language you basically use 7700 unless its explicitly one of the other two cases. In your example I would say a hijacking supersedes all but as with many things its a case by case kind of things.

Ultimately the codes are there as somewhat of a backup to actual radio telephony and cover 3 important cases the way I see it. In an actual scenario you use the code that is most applicable to the situation as the pilot in command sees it.

  7500: The aircraft has been hijacked, they may not know what I (the pilot) is fiddling with so Im sending you this code since I cant say anything on the radio

  7600: My radios are down, I may not be able to send or receive transmissions. There may be nothing else wrong with the aircraft in which case radio out procedures prevail. The tower may need to get a light gun out. In IMC see this question.

  7700: Somethings going on this is how Im telling ATC for what ever reason chatting on the radio is insufficient. As to what the advantages are see this question.

This ICAO document on reply codes states that

  ATS authorities should establish the procedures for the allotment of SSR codes in conformity with Regional Air Navigation agreements, taking into account other users of the system.

  2.1.4.2 The following Mode A codes shall be reserved for special purposes

  2.1.4.2.1 Code 7700 ... {2}7600 ... {3}7500 ...

So what will happen when you use the code is somewhat up to local jurisdiction and you should know what will happen when you enter the code to help you (as the pilot in command) decide which one to use.


Why does the US use two types of aerial refueling?

The flying boom method uses a rigid boom which is "flown" by an operator in coordination with the pilot in order to make a connection with a receptacle on the second aircraft. The boom is retracted when not in use. Though it can do damage if it comes in contact with an aircraft, the operator can quickly move the boom if needed.

The probe and drogue method uses a trailing hose with a basket on the end. Pilots will guide a probe on their aircraft into the basket to connect with the hose. The hoses are retracted when not in use. Though the crew has less control of the drogue, which can still cause damage, there is less danger to the aircraft than from a boom, and it could allow the aircraft to stay further away from the tanker.

The boom method was developed early on in the Cold War, when Strategic Air Command had many large bombers that needed to be refueled. They needed a method that would transfer fuel as fast as possible in order to reduce the time it took to transfer the large amounts of fuel needed. Because the boom is rigid, it is capable of a higher transfer rate. The importance of bombers meant that SAC got their way, and the KC-135 fleet was equipped with booms. Today, almost all US Air Force planes capable of aerial refueling use the boom system.

The US Navy on the other hand, along with most aircraft in other countries, uses the drogue system. Though this method is not capable of the high transfer rates of a boom, it is much more flexible. A refueling aircraft may only be fitted with one boom, and this requires extra design work and integration with the fuselage. The drogue system, on the other hand, is more simple, and does not need a dedicated operator. This means that it can be more easily fitted to the refueling aircraft, even other fighter planes, and larger aircraft can have multiple drogues.

Another point is that smaller aircraft such as fighters are not capable of receiving fuel at the full rate the boom provides, so they have less benefit from the system. Although a boom can have a drogue adapter attached, this still commits the tanker to one aircraft at a time and one type of system per flight. Also, aircraft such as helicopters cannot use a boom system.

When the Air Force was looking at a replacement for its tanker fleet in the early 2000s, a study was done to determine what standard the new tanker should support.

The report suggests some options for the best combination of methods. In the end, the Air Force selected the KC-46 for the contract, which will include both the boom and the drogue options for refueling. This will provide better support to aircraft from other branches or countries, while maintaining support of the existing aircraft that use a boom.


What is the reason for the different types of valve heads (mushroom, tulip, semi tulip) in reciprocating engines?

That part of the shape comes down to a couple of factors.

First of all, you want valves to be light. Second, the outside of the valve's head forms part of the combustion chamber.

The shape of the combustion chamber influences a couple of things. A hemispherical chamber tends to help "breathing"--the ability to get fuel-air mixture into the chamber and get exhaust out of the chamber.

Another common shape is a wedge. A wedge shape helps "swirl" the fuel/air mixture around in the chamber during the compression stroke, to ensure the fuel and air are evenly mixed, so it burns more evenly and completely.

The former tends to improve performance in terms of power per unit of displacement, while the latter tends to improve performance more in terms of power extracted per unit of fuel consumed.

A mushroom shaped head is typically (as shown above) used with a hollow valve. In this case, the valve is typically filled with sodium. Sodium is a metal with a very low melting point, so in normal operation, the valve is filled with liquid sodium. Liquid sodium is a very good heat conductor, so it conducts heat from the head of the valve to the stem, which is surrounded by oil and a valve guide, which help conduct the heat away. The mushroom head makes it relatively easy to maintain a uniform thickness of steel between the outside of the valve and the sodium inside, so the heat is conducted away relatively evenly--extreme heat gradients can lead to failure (e.g., the valve cracking). The valve's movement helps circulate the liquid sodium around to help heat circulation, and keep the temperature of the outside of the valve relatively uniform.

Another factor favoring a tulip shape (or similar) is reducing valve float. The heavier the valve, the stronger of a spring you need to ensure that the valve closes as soon as the cam lets it. If the valve stays open (floats) it can reduce power, or in more extreme cases the valve can contact the piston, which will normally lead to engine failure requiring a full inspection and rebuild at a minimum (and quite possibly requiring complete replacement). Stronger valve springs can help too, but they put more wear and tear on the drive train (e.g., timing belt) and "steal" more power from the engine to turn the cam.


Did Boeing or Lockheed ever seriously consider releasing a widebody airliner powered by low-bypass engines?

I am not aware of any manufacturer making a serious proposal to develop a jumbo jet with low bypass-ratio engines. Most airline manufacturers tend to develop a plane from  customers requirements, whether that customer is military or civilian. Civilian airlines in the late 1950s were already nervous about the much higher costs for jet-powered aircraft and there was no call at this time for an even larger plane.

To get the most value for their development efforts, airplane companies tend to look at if they can develop a commercial and military version. As an example, Boeing tries to develop a commercial variant to all of their military planes and vice versa. Starting with the Boeing 307 Stratoliner and continuing with the the Boeing B-52 Stratofortress and the Boeing B-47 Stratojet, Boeing worked to develop a passenger variant as well. There was discussions with making the B-52 into a passenger plane, but commercial airlines were not interested. Some of the reasons were the the hull was very narrow, much of it un-pressurized and in many ways, it  would have been ill-suited for passenger use. The plane would have had identical engines to the B-52. I could not locate any drawings of what it would look like. The push for a passenger plane became the Boeing 367-80, which developed into the Boeing KC-135 Stratotanker and the Boeing 707, which entered into service in 1958.

Lockheed had it's hands full with fulfilling orders for the Constellation. It developed some great military planes, but never pursued a passenger jet until the Lockheed L-1011 TriStar which first flew in 1970.

After World War II, Douglas lost a lot of military business and was forced to scale back. It's first jet that became a passenger jet came out of the development of a tanker for the Air Force that eventually became the Boeing KC-135 tanker. The reason they developed the Douglas DC-8 was that Pan Am ordered 20 of them and they could see the future was jet-powered.

The next big jump in airplane size came out of a development effort by the Air Force. In 1964 they asked Boeing, Douglas, General Dynamics, Lockheed, and Martin Marietta to develop a prototype for the CX-HLS cargo plane. This was much larger than anything that existed at the time. In this proposal, the Air Force was asking for high efficiency engines as well as the ability to carry a lot of weight. The two final prototypes became the Lockheed C-5 Galaxy and the Boeing 747.

By this time, the age of low-bypass-ratio engines was over because of the much better efficiency available in newer high-bypass engines.


Delta fleet plans - all Airbus? (and Bombardier)

It does not seem that Delta is on the way to an all-Airbus fleet. As a starting point, they plan to take delivery this year of the first of at least 75 of the Bombardier CS100. That points to many years to come of non-Airbus aircraft for them. They also continue to receive new Boeing 737-900ER aircraft.


Does ICAO require (or suggest) set of technical statuses of radar and its subsystems?

These statuses are not defined by nor required explicitly by ICAO.

The details of how a radar (or other surveillance) system communicates with downstream ATC systems are defined in a technical specification documents, typically produced by EUROCAE and/or RTCA.

The ASTERIX specifications are maintained by EUROCONTROL and only give the format in which surveillance ground systems communicate amongst each other. The specifications were originally intended to facilitate surveillance data exchange between European countries, but they have now been adopted by many countries outside Europe.

Category 002 (old) and 034 define the status messages monoradar systems use to update downstream systems (radar trackers, displays) on the radar's status.


Lockheed Martin Sabre Warrior UCAV (concept):

Source

Source

From Defence Forum India:

  The Sabre Warrior drone is 46 feet long, with a 36-foot wingspan,
  capable of taking off with 30,000 pounds of load using a 22,000-pound
  trust afterburning turbofan engine. It has two modular payload
  sections, which can be changed by soldiers in the field. Each bay can
  handle one 2,000 pound or two AIM-120 AMRAAM missiles or 10 smart
  bombs or sensors, or even fuel for extended range missions—”even
  while this thing is air refuelable.

  Its twin nose can also hold multiple sensors, which are
  interchangeable. And it is designed so there could be a version with a
  cockpit, so they can send man version as an on-the-scene controller,
  overlooking over the unmanned versions.

The Raptor F-22 is a 5th generation fighter, Sabre Warrior the 6th.
Requirements worked with DARPA and USAF.
It has been considered for the UK Future Offensive Air System (FOAS), cancelled in 2005.
More on Youtube.


How to calculate the lift coefficient of a multi element airfoil?

It depends. Are the c$_l$ values referenced to the local chord? Then you need to convert them to the chord of the full airfoil so they can be added.

I wonder, however, how you can have individual lift coefficients without the total lift coefficient. If the single parts are isolated, their pressure distribution is different from that in the context of the full airfoil. Please check the source of the lift coefficients and make sure that they are representative of the local lift when flown in combination with all other parts.

Normally, what needs to be done is to use a multi-element airfoil code and calculate the lift coefficient of the full wing with all high-lift devices in place.


How far does an A320 travel horizontally while climbing to / descending from cruise altitude?

Of the main variables are the weight at brake release, and how high the cruise FL is. Luckily the manufacturers publish this data for flight planning (actual mileage will vary).

The climb distance you are looking for is the lower-left value in each box in the example below, which is applicable to the 320-family:

You can find it in the FCOM under Performance > Climb. A similar table exists for descents. Of course the values do not include the wind correction. For climbing other tables exist for the various deviations from ISA (lapse rate).

If you want to calculate it from scratch, then you need to have more data before you begin, I recommend these posts:

How to find total climbing time based on Rate of Climb?
Is there a formula to calculate ground distance traveled given rate of climb and true airspeed?
Is it possible to determine the approximate climb rate of an aircraft knowing its top speed, engine power and weight?
How can I calculate maximum rate of climb?


How does the load transfer from a prop to the airframe?

The engine mount is an important component that transfers the prop thrust to the airframe. It's clearly visible in this photograph of a fast and powerful plane, a  Bf109. Of course, bearings transfer thrust between the rotating and static parts. That is common to all engine-propelled vehicles, ships, cars, planes... The main thrust load, in the picture showing the turbofan, is taken by the tapered roller bearings.


How can I identify airliner types that don't have ACARS?

ACARS is a operator specific (optional) system. It depends on the operators requirements if an aircraft is equipped with ACARS or not. You can't tie it to an aircraft model or variant. As a rule of thumb: The older the aircraft, the less likely it is ACARS equipped.


Do I have to do all exercises during a checkride, even if I did them in a previous one?

Yes, if this is your initial rating on a Commercial certificate, you have to do all of that rating's required tasks. A checkride for a given certificate is always self-contained. In the case of an additional Commercial rating (ASEL, for example) you can refer to the appropriate "Additional Rating Task Table" and you'll see that some areas are already covered by the existing Commercial rating.

If you look closely, you'll notice that the PTS standards for the same maneuvers are more precise for Commercial than they are for Private. Notice that Steep Turns differ in both bank angle and execution technique:

Commercial (from FAA-S-8081-12C)

  Task A: Steep Turns (AMEL and AMES)

  References: FAA-H-8083-3; POH/AFM.

  Objective: To determine that the applicant:

  Exhibits satisfactory knowledge of the elements related to steep turns.
  Establishes the manufacturer’s recommended airspeed or if one is not stated, a safe airspeed not to exceed VA.
  Rolls into a coordinated 360° steep turn with at least a 50° bank, followed by a 360° steep turn in the opposite direction.
  Divides attention between airplane control and orientation.
  Maintains the entry altitude, ±100 feet, airspeed, ±10 knots,
  bank, ±5°; and rolls out on the entry heading, ±10°.

Private (from FAA-S-8081-14B)

  Task A: Steep Turns (AMEL and AMES)

  References: FAA-H-8083-3; POH/AFM.

  Objective: To determine that the applicant:

  Exhibits satisfactory knowledge of the elements related to steep turns.
  Establishes the manufacturer’s recommended airspeed or if one is not stated, a safe airspeed not to exceed VA.
  Rolls into a coordinated 360° turn; maintains a 45° bank.
  Performs the task in the opposite direction, as specified by
  the examiner.
  Divides attention between airplane control and orientation.
  Maintains the entry altitude, ±100 feet, airspeed, ±10 knots,
  bank, ±5°; and rolls out on the entry heading, ±10°.


How do Air Traffic Controllers determine which planes take off in a certain order?

The busier airports around the world are slot controlled, meaning that each flight is assigned a designated departure or arrival time that they must be ready for. In this case it’s pretty straightforward who goes first - whoever has the first slot.

Non-slot controlled airports are usually on a first come first served basis, with some exceptions. Private flights have to wait for scheduled airline flights, and airliners wait for air ambulances. If two aircraft are departing on the same route, the faster one will go first if they have a significant speed difference. And the heaviest aircraft need greater separation for wake turbulence, so an A320 might get preference over an A380.

That doesn’t mean your A380 will have to wait for 15 A320s though. In practice these are only guidelines and the decision as to who goes first is based on the needs of the traffic system on the whole considering all of the factors at the time.


Can pilots smoke in the cockpit of an airliner?

All of the most significant countries prohibit smoking on airline flights, either through national, industry, or airline regulations. This applies to crew through different regulations, but as strictly as to the passengers.

Pilots can and sometimes do smoke in the cockpits of business jets. These can be as large as airliners (see BBJ), but usually aren't.


How is the battery power on the Airbus A340's electric system switched?

From A340 FCOM 1.24.20 P2 (REV 8):

  BAT 1 (2) pb sw

  Controls the operation of the corresponding Battery Charge Limiter

  AUTO:

  The Battery Charge Limiter controls automatically the connection
  and the disconnection of the corresponding battery tot the DC BAT BUS
  by closing and opening of the battery line contactor.

  The batteries
  are connected to the DC BAT BUS in the following cases:

  Battery voltage below 26.5 Volts (battery charge). The charging cycle ends when battery charge current goes below 4 Amperes (for 10 seconds on ground 30 minutes is flight)
  On the
  ground (with speed below 50 knots) when batteries only are supplying
  the aircraft.

My understanding is that for the DC BAT BUS this means when a button is set to AUTO the corresponding battery is connected when that battery needs to be charged or:

The aircraft has a speed below 50 knots AND
The only power source is batteries (i.e. no generators, APU or external power supply are connected to the electrical network)

A note further down mentions that the batteries are disconnected  when the voltage drops below 23 Volts for more than 16 seconds, in order to protect the battery from discharging completely.

For the DC ESS BUS it states:

  The batteries are connected to the DC ESS BUS when batteries only are
  supplying

  in flight
  on the ground (speed below 50 knots) provided they are
  both selected auto

That clearly states that both push button switches need to be set to AUTO in order for the DC ESS BUS to be powered from the batteries on the ground.


Per the AIM, Helicopter pilots may fly non-copter approaches at half the published visibility. Where is that in the FAR?

I'm not sure what source you're looking at for the FARs but the reduction is indeed there in 14 CFR 97.3:

Copter procedures means helicopter procedures, with applicable minimums as prescribed in §97.35. Helicopters may also use other
procedures prescribed in subpart C of this part and may use the
Category A minimum descent altitude (MDA), or decision altitude or
decision height (DA/DH). For other than “copter-only” approaches, the
required visibility minimum for Category I approaches may be reduced
to one-half the published visibility minimum for Category A aircraft,
but in no case may it be reduced to less than one-quarter mile
prevailing visibility, or, if reported, 1,200 feet RVR. Reduction of
visibility minima on Category II instrument approach procedures is
prohibited.


How reliable are aircraft cutaway drawings from Flightglobal?

These cutaways are just general representations of what structural components go into the aircraft; they are NOT engineering drawings nor should they be used as such.

In general the OEMs and the engineering departments for the airlines are pretty sensitive about releasing engineering data for proprietary reasons.  If you are working on a product closely with an OEM or an airline, they may be able to grant you a license to access such data, generally for a substantial fee. Or, if you have a client who will allow you access to the aircraft, you may be able to take engineering photos and/or make detailed measurements directly on the aircraft.


Why the different wing and tail designs in similar sized jets vs turbo prop?

Well, for starters, the speeds are actually pretty significantly different. The Cseries is almost 25% faster than the Q400. Swept airfoils are much more efficient at those higher speeds, as are jet engines.

The Q400 is also a wildly stretched version of the original DeHavilland Canada DHC-8 (Dash 8), which was itself based on the 4-engine DHC-7 (Dash 7) STOL airliner. DHC has a lot of history building short takeoff and landing aircraft with pretty extreme performance, and a lot of that colored the design of the Dash 8. What you see today in the Q400 is the result of about 70 years of backcountry aircraft design, applied to a commuter airliner.

The Cseries, on the other hand, is a clean-sheet Bombardier design meant to compete with the E-jets and the smallest 737s (and 717).

Hopefully that answers your questions!


Can I pilot a plane while having a chronic mental health condition?

You have a couple of options here:

As Skip Miller said, you can take flight lessons. Up until you want to solo, you don't need a medical certificate. Often flight schools have "Discovery Flights" for a reduced cost that still allows you to fly left seat and get half an hour to an hour of flight. Careful though, its addicting.

Actual costs for this range from \$75 to over \$300 depending on the type of aircraft you are going to fly. Hourly rates for a Cessna 152 average around \$90 an hour, to a 172 up to \$150 an hour, and more sleek aircraft like a Cirrus SR-22 at \$300 per hour or more. Instructor rates go from \$35 per hour to \$65 per hour (typically) depending on the type of instruction.

Another option is to find a pilot who wants to build hours and go flying. They may let you fly the airplane around a little bit, but you'll most likely be flying right seat and probably won't let you do the more complicated phases of flight like take-off/landing and operations in controlled airspace. If you find a pilot willing to do this then you can share costs (split down the middle).

By the way don't get discouraged about your medical condition if you really want to fly. There are also a few options there too. First, you could go through the rather lengthy process with the FAA to have your case reviewed and if possible issued a special issuance medical certificate. Some of what you list are automatically disqualifying depending on the medications you may take, but the AOPA has a good read on mental health and getting medicals issued.

Second, you could get a sport pilot license, which also does not require a medical (just a drivers license). There may be hiccups with your conditions here too, so its best to talk to an AME or flight instructor before getting too deep.

Let me answer your specific question:

  Is there a way I can fly with a copilot without a pilot's license?

I take this to mean that the "copilot" is a non-pilot rated passenger. Unless you are a certificated pilot, then no. A "co-pilot" must be just that, a pilot. Otherwise they are just a passenger sitting in the front seat. Since that person is a passenger, you must be a fully licensed pilot to fly with them (students cannot take passengers).

If the copilot is a pilot rated individual, then yes, you can go flying with them (provided it is not a Part 135 flight). That person must be rated for the aircraft that you are flying and must meet currency requirements to carry passengers (you). You as a passenger are allowed to manipulate the controls under the supervision of the pilot provided the pilot is pilot in command and unless the pilot is a CFI, they are not providing instruction.


How is notification of UAV flight handled in an area with multiple heliports?

Tl;dr: Yes, you are required to contact all airports and heliports within a 5-mile radius.

Unless you have a part 107 certificate you are operating under the rules of 14 CFR Part 101, Subpart E - Special Rule for Model Aircraft. Since the FAA is generally prohibited from setting rules for hobbyist operations, the only specific regulations are under this subpart. They are frustratingly unclear and refer most rulemaking to undefined “nationwide community-based organizations.” Although which organizations, or even what such an organization consists of, are not defined, the FAA works closely with the Academy of Model Aeronautics which publishes a handbook for safe operation.

One of the few specific regulations subpart E does include is the following.

  14 CFR § 101.41 (e) When flown within 5 miles of an airport, the operator of the aircraft provides the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport) with prior notice of the operation.

This means that to be in compliance you must notify all 32 heliports in your area. Note that it does not say you must get permission, only that you must provide prior notice. It also doesn’t say what kind of notice, nor how far in advance, nor if you must notify them every time you fly or if it can be an ongoing situation.

Mongo’s suggestion of mailing a letter to each one would be a good approach. Make sure you keep a copy of the letter sent and a record of who you sent them to. That way if a problem arises you have documentation that you did make the required notification.

Beyond notification, there is no mention of airspace classes, flight restrictions or anything else. It only specifies that:

  14 CFR § 101.41 (d) The aircraft is operated in a manner that does not interfere with and gives way to any manned aircraft

That’s not to say that you don’t have to follow flight restrictions. That would fall under the elastic clause:

  14 CFR § 101.43 Endangering the safety of the National Airspace System.
  No person may operate model aircraft so as to endanger the safety of the national airspace system.

If you are planning to fly for research then you should certainly get a part 107 suas pilot certificate. Part 107 regulations are much more well-defined. If operating under part 107 there is no requirement to notify the airports and heliports. An suas license requires you to know how to read charts and know what type of airspace you are operating in. By default part 107 is restricted to uncontrolled airspace (class G). To operate in controlled airspace you must apply for a waiver and follow the rules of the waiver. Once you have a waiver for controlled airspace the requirements for getting permission depend on the specific airspace you need to fly in. Under part 107, in class G airspace there is no requirement to notify anyone.


Why there is a helicopter sitting north of madras, OR, , above the warm springs reservation every single night?

If you are looking up at a bright thing in the southwestern or western sky before 11 PM in March 2020 and you aren't also able to locate the planet Venus at the same time, then the bright thing is the planet Venus.

Venus is very high and bright in southwestern or western sky in the evenings these days.  Unless it is very near the horizon, it appears to shine with a white steady light.  With a clear distant horizon, it will set in the west about 23:30 PDT at your location.  (Calculated via this on-line tool.)

The star Sirius is also still prominent in the evening sky.  It can appear to flicker quite dramatically, flashing from red to blue, especially when near the horizon, but is nowhere near as bright as Venus.  With a clear distant horizon it will set in the southwest at about 2:50 AM PDT at your location.  (Calculated via this on-line tool.)

Does the object make a helicopter sound, or some other sound, or no sound?

Is the light steady, or is it definitely blinking completely off and then back on?  What color(s)?   What direction is the light from you?  Does it stay in the same direction from you if you drive 10 miles down a road and look at again? (I.e. does it appear to "follow" you as some observers have often said about such things?)  Is it so high that it could not be a tower?  Does it get nearer to the western horizon over the course of several hours? Can you establish what time it "sets" below the horizon, if it does? Is it still visible at midnight? Is it still visible in the pre-dawn twilight? If you have access to binoculars, does it look like a tiny round circle that is not flashing or flickering when seen through the binoculars?

Odds seem good that it is Venus, but the answers to these questions should confirm or reject this hypothesis.  Due to the path of the ecliptic, Venus may be well north of due west even near the spring equinox when the sun is setting nearly due west.

If it is definitely a flying vehicle, which seems unlikely, you can't assume it is not an unmanned drone/ UAV.


Why is the pitot tube located near the nose?

There are several reasons to have the pressure sensors in the front section of the fuselage.

The further aft the more turbulent the airflow is and the thicker the boundary layer caused by the fuselage. This would cause strong fluctuations of the measured pressure and the reading could be inaccurate. Far forward the boundary layer is the thinnest because the boundary layer thickness grows with the distance traveled along the surface.
The position on the nose should be less sensitive to angle of attack and side slip angle changes. Having the sensors on the side of the fuselage would cause significant changes in pressure measurements depending on the aircraft attitude relative to the incoming air.
The pressure sensor in the nose is close to the cockpit instrumentation and avionics computers. Pressure tubes can be short and cannot be disconnected by mechanical forces that easily.
There is no ground equipment moving close to them. Having them further aft could easily damage the sensors during baggage or passenger loading/unloading.
During winter months airplanes have to be sprayed with de-icing fluids. Up front they are not flooded by these substances and are spaced far away from the affected areas.

Some aircraft have the sensors located on the wings. The Cessna 172 pitot tube is one example that comes to mind.


A magneto is a gear driven electric generation device connected to the crankshaft of the engine. It supplies the ignition system (spark plugs) with power.

Each engine has two magnetos. Each cylinder has two plugs. Each magneto supplies one plug in each of the cylinders. This makes the ignition system redundant. If a magneto fails, the other magneto can sustain the engine.

Since the rest of the aircraft's electrical system is supplied by a belt driven alternator/generator, the engine is electrically isolated from any other electrical issues. If you lose electric power in the cockpit, your engine will still run. If you have to shut off electricity because of a cockpit fire, your engine will still run.

The scale of the image below is a little distorted. I had to get my phone pretty close to the oil filter for sufficient lighting.

MAGNETO #1 mounted below and to the side of the oil filter on the back of the engine

STARTER mounted under the front of the engine, connected to the flywheel only when in use

ALTERNATOR mounted under the front of the engine, connected via an accessory belt to the crankshaft


Does anyone know more about the 1958 Heinkel-211 project?


Could the filming of the 747 in "Awakenings" have taken place during the 747 flight testing?

Nope. It wasn't filmed during testing.

When Dr. Sayer takes Leonard out into the city for the first time, they see (among other things) an aircraft landing - a Boeing 747. The movie takes place in 1969 and the first revenue flight of the Boeing 747 was January 21st, 1970. Additionally, the 747 is in El Al livery that was used around 1990 (IMDb).

(airliners.net) Photo date: October 27, 1991.
Could the 747 have been filmed while landing at JFK in the summer of 1969?
It's plausible, because during the flight testing the 747 flew to Paris and it could have very well used JFK (runways were upgraded in the late 60s):

[Boeing took] a test aircraft to the 28th Paris Air Show in mid-1969, where it was displayed to the public for the first time (Wikipedia).

and

[JFK] was designed for aircraft up to 300,000-pound (140,000 kg) gross weight and had to be modified in the late 1960s to accommodate Boeing 747s (Wikipedia).


Can perfect turn coordination automation be achieved by linking rudder to aileron?

The mechanical linkage from control column (aileron) only addresses one of the things that affect coordination, the adverse yaw. It is the most significant one, but not the only. Other reasons you may need some rudder deflection in coordinated flight include:

Compensating for P-factor. At high angle of attack (slow flight) the propeller blade going up sees a lower angle of attack than the propeller blade going down, creating asymmetry of thrust. The effect depends on engine power and speed, making it too complex to compensate by just mechanical linkages.
The rotating propeller slipstream also creates asymmetrical force on the rudder, requiring compensation depending on engine power and speed.
In tail-draggers, the propeller precession creates rather significant yawing moment as the tail lifts off that needs to be connected using rudder, otherwise the plane could ground-loop. Tail-draggers generally require active control by rudder, because they are directionally unstable on the ground.
In multi-engine aircraft, asymmetric thrust in the event of engine failure. For multi-engine aircraft this is the most significant yawing moment that the rudder must be able to compensate.
And last but not least, rudder is needed to damp the Dutch roll. I've never heard that mentioned as problem in utility aircraft, but it is a big problem for transport aircraft and a reason why they usually come with a yaw damper.

The yaw damper is a feedback controller that monitors the lateral acceleration and other parameters (yaw and roll rate) and applies rudder to damp the dutch roll, and also to provide coordination to turns flown by autopilot where usually the autopilot directly commands the ailerons and rudder is left up the the yaw damper. So yes, providing coordination is possible, but not via simple mechanical linkages. And of course the rudder pedals still need to be there so uncoordinated flight is possible for any of the reasons already listed in Ron Beyer's answer.


What are these engine inlet devices used for?

The first photo shows the engine air intake screen. Its basically a screen to prevent FOD ingestion, as you noted. From CH-47 Theory of Operations:

Engine Inlet Screens
An engine inlet screen which maximizes foreign object damage (FOD) is installed on each engine. The reduction in engine power available with screens installed is negligible. The engine inlet screens have bypass panels.  These two panels are on the aft end of each screen. Quick release fasteners attach the panels to the screens. They are removed if the ambient temperature
is 4°C or below and there is visible moisture

I'm pretty sure it is supposed to be minimizes foreign object damage.

It is an All Weather Screen (AWS) intended primarily to prevent ingestion of large items that would cause foreign object damage to the compressor blades.

By Mr.Z-man - Own work, CC BY-SA 3.0, Link
The second photo shows the Engine Air Particle Separator(EAPS) unit, which in this case is the  Pall PUREair System

Pall PUREair system; image from Pall aerospace
The EAPS is there primarily to protect against ingestion of sand and dust, which, according to Why an Engine Air Particle Separator (EAPS)? can cause multiple problems like,

erosion of compressor blades

clogging turbine cooling passages

cause sulphidation, corrosion and overheating

As the article notes,

A CH-47 in the desert with only the AWS could achieve only 12 landings before both engines were changed. With EAPS, it did 13 landings with no change in horsepower. in another desert test CH-47 engines with AWS deteriorated to an unacceptable level in only 30 hours. With EAPS, there was no degradation.

In case of desert environments, EAPS is a must if you want your engine to survive any more than double digit hours. This particular type of EAPS belongs to the Vortex tube separators and uses a vortex generator to separate the sand and dust from air.

Contaminated air entering the ... air cleaner tube assembly is given a swirling motion induced by the vortex generator. This swirling motion causes the heavier dirt particle and water droplets to be thrown radially outward by centrifugal force toward the wall of the tube.

Principle of EAPS operation, image from Pall aerospace.
You can find about other types and their operation in A Comparative Study of Helicopter Engine Particle Separators


Can crews hand-fly an RNP AR approach in IMC?

Each operator can impose their own requirements that are at least as strict as what the FAA requires, and these tend to be more strict.  For instance, one operator I'm familiar with requires both INS's to be working, not just one.

For that operator, it's allowable to hand-fly an RNP approach using the Flight Director if the RNP is 0.3 NM, but if it's any lower then the autopilot must be used.


Why does this 757 have a propeller engine attached to the fuselage?

From the description below the image you linked:

  The Honeywell, Boeing 757 test bed appeared on static display for a few days before departing half way through the event.

A testbed aircraft is an aircraft used for flight research or testing new equipment such as engines.

You can see other photos without engine or with a jet engine instead of a propeller one.

The engine is not needed to fly, but is being tested, and apparently that position has been deemed a good solution to the problem "where do we attach an extra engine we need to do tests on?".


Does an increase in lift always cause an increase in lift-induced drag?

When looking at statements like these, it's important to consider which parameters are varied and which parameters remain fixed.

Let's get this out of the way first by correcting your statements:

Lift increases with increase in airspeed with constant angle of attack but induced drag reduces with increase in airspeed with lift force remaining constant
Higher Aspect ratio wings generates greater lift with constant wing surface area but creates less induced drag with lift force remaining constant.

As you can see, each half of your statement refers to a different scenario. The bottom line is that for lift generation, it's more efficient to give a small change of velocity to a large air mass, than a large change of velocity to a small air mass (because force is generated by momentum change which is linear in velocity, and induced drag is due to the kinetic energy imparted on the air mass which is quadratic in velocity).

When flying fast or with slender (high aspect ratio) wings, you affect a larger air mass every second. You can do two things: either keep your angle of attack constant and get a lot of lift out of the air mass, or in case you don't want to do aerobatic maneuvers, you decrease the angle of attack until lift once more equals weight, and get less induced drag.


What's the idea behind leaving control of slats and flaps to pilots in autopilot?

The key thing is that not every flight is the same. Sometimes the landing gear is left up for longer for noise abatement, sometimes it goes out earlier if more drag is required. On a non-straight in approach it's sometimes a good idea to extend the gear earlier. If the brakes heat up too much on the taxi before takeoff, the gear may need to be left down for a bit for extra cooling.

Flaps are a bit different as they are typically set for a certain speed, but the principle still applies. For example if turbulence is encountered which effects the airspeed, having the autopilot moving the flaps the second the flap movement speed is triggered is unhelpful.

Basically, these are things that require the active judgement of the pilots considering the individual factors of that specific flight. It's impossible to automate all of this satisfactorily even with pre-planning. Even if you could it would further introduce an overreliance on automation for very little gain.


Why don't they build airplanes from 3D printer plastic?

My assumption is that there are plastics lighter and stronger than the materials used to build planes.

That is not a correct assumption.

Typical 3D printer plastics have a best-case tensile strength of 45-50 MPa.
Aluminum 7075, a common aerospace alloy, has a tensile strength of 500-570 MPa.

After dividing by specific gravity, that's at a 1:4-1:5 ratio of specific strength in favor of metal. There is no significant application in which 3D printer plastics, the properties of which are driven by viscosity, adhesion, and other printing qualities, would offer better strength-to-weight than aerospace metals and fiber-reinforced composites.

Some amount of 3D-printed plastics will likely appear in cabin interiors, for low-volume parts or complex hollowed-out parts, not subjected to significant stresses. But load-bearing parts require high strength and high strength-to-weight ratio. If it's too heavy, it won't take off, and if the material's too weak, it won't stay in one piece.

So the brief answer is, they don't build airplanes from 3D printer plastic (or clay, or plaster, or thatch) because they want them to fly.


Why is the alternate static pressure lower than the standard static vent pressure regardless of the venturi effect on both?

A venturi effect pertains to a change in pressure caused by a CHANGE in airflow velocity.  The static air pressure at the static port is not automatically lower just because the air is in motion there.

After all, the air within the fuselage (and within the piping leading to the static port) is in motion relative to the outside airmass, just as much as the outside airmass is in motion relative to the air inside the fuselage.

However, the overall dynamics of the flow around the fuselage do produce a net drop in pressure inside the fuselage, if it is unsealed.  There must be locations on the fuselage that would be bad places to put a static port because they are the planes where this pressure drop is being created by the overall dynamics of the flow.

Related answer-- In an unpressurized cabin, why is the cockpit ambient pressure lower than the outside pressure?

Another highly related answer-- Does the pressure at the static ports drop as the aircraft's speed increases?


Why isn't there a single start button for all systems on aircraft?

Good question, actually the history of aviation teach us that: any technology on board is robust and capable to not crash or reboot for nothing. Behaviour you can see sometimes on brand new technologies. So everything which is on board is ten years old technology.

In the same time, the pilot needs to be able to switch off or on some systems if they are failing, if you automated all the sequence it start to be difficult to know if the pilot has the real control of the system.

It is only matter of safety and control. Because we already know that we are capable to automatically take off, fly and land UAVs. Why not in an airliner? Because safety. It has to be proven for a long time to convince safety agencies to make the step forward.


How can the concept of "intercept geometry" be explained in simple terms?

Intercept geometry is the bubble of space in which the SA-2 missile can be effective against a specific aircraft. Crucial here is the detection range of the radar system guiding the missile, given here as 40 nm.

Depending on the speed of the target, the missile has only a limited time to ascend to the altitude of the target and to close in. The combination of speed and altitude of the SR-71 (1854 kt), moving at more than 30 nm per minute, will leave only a very small intercept geometry, and it has to overfly the missile launcher almost directly to be vulnerable. Once the target flies above 90.000 ft and Mach 3.5 (or employs effective countermeasures), it will be unassailable by the SA-2.

Contrast that with the fate of an aircraft flying only Mach 1 at 60.000 ft (which equals 573.6 kt): Moving at less than 10 nm per minute, its course can go past the launcher with a 25 nm offset, but it will still be in range of the Fan Song - SA-2 combination.


Has the "Foote takeoff" technique really existed, and how did it work?

The 1952 takeoff accident you read about was piloted by Captain Harry Foote. The technique got its name after the accident, which Captain Foote was blamed for (Comet! The World's First Jet Airliner, page 125).

Pushing the nose down is not standard though, rather a corrective measure to over-rotation past 6°. The article quoted below covers the proper technique and the 1952 accident:

  The B.O.A.C. Training Manual recommends the following take-off technique:

    At 80 kts. the nose should be lifted until the rumble of the nose wheel ceases. Care should be taken not to overdo this and adopt an exaggerated tail-down attitude with a consequent poor acceleration.

  (...)

  Take-off tests by the manufacturers have shown that a constant 6° incidence of fuselage during the ground run gives good results for distance run and for climb-away behaviour. They have also shown that an increase of incidence to 9° results in a partially stalled wing inducing high drag which appreciably affects the aircraft’s acceleration, and that the symptoms are noticeable to the pilot as a low frequency buffet. The aircraft recovers from its semistalled position if the nose is pushed well down. [emphasis added]

  (...)

  It was the opinion of the investigators that the accident was due to an error of judgment by the captain in not appreciating the excessive nose-up attitude of the aircraft during the take-off.

  (flightsafetyaustralia.com)

As @RAC said, VR didn't exist. Judging by the historic FAA regulations, VR and the takeoff speeds in general for Part 25 came about in the mid-60s.


Specifically, the video is one of the Apple TV's screensaver images, taken at LAX (this one in particular [WARNING: high-def video link, ~267MB] [alternate YouTube version, thanks to Mark]).

It's not CGI. Apple used a variety of drones and helicopters to shoot the footage.

While the airspace around the airport is generally controlled (not restricted), there are a number of VFR flight routes that cross the airport. These can be seen on the Los Angeles Terminal Area Chart. In the case of this specific video, permission was presumably coordinated with ATC. As the video was taken down the middle of the airport, between the sets of runways, it's likely that taking it didn't interfere with air traffic; traffic arriving/departing LAX won't be flying there.

This tweet (with photos) just crossed my feed. @ethanklapper: Today was special. Chartered a helicopter and flew above LAX at 2,500 feet. Took 500 pictures in an hour. Can’t wait to share more!

I imagine a similar process was used for this video.


Is the Bill Of Sale required for deregistration?

In the US you don't need a bill of sale because the aircraft may not have been sold. The FAA's definition says:

  Deregistered Aircraft An aircraft that has been removed from the U.S. Civil Aircraft Register at the owner's request. Aircraft are
  generally removed for the following reasons: exported, destroyed,
  salvaged, dismantled, or permanently retired from service.

There would be no bill of sale for a destroyed aircraft, for example.

If you're asking about handling the FAA registration when you sell an aircraft, according to AOPA's guide you have to sign and return the current registration certificate, and the FAA will issue a new one to the buyer.


What phraseology does ATC use with jet fighter pilots?

This ICAO document lays out the guidelines pretty well in short, in most places military aircraft (of any kind) are treated no different than civilian aircraft and are expected to comply with local regulations which include radio procedures. ATC will clear an F-22 for take off no differently than a Cessna 150 (with perhaps different expected climb rates ;) )

Of course most jurisdictions that belong to countries that have some kind of an Air Force will generally coordinate with them for special types of operations and the organization that controls the airspace expects that anyone wanting to conduct special operations will coordinate with them.

This typically happens in controlled areas like an MOA or for safer operations near a base. I fly quite a bit near a large base and often while transitioning through their airspace its not uncommon to get warnings of high speed or low altitude activity. Either way the aircraft is expected to make radio calls and adhere to any regulations or pre cleared operations.


In larger aircraft you may not be able to execute a go around once you have touched down but its not always because of weather. This mainly has to do with the fact that once a plane touches down (situation depending) it may have already committed to the landing and will no longer be able to get airborne with the remaining runway. There is a discussion here on the topic and an article here that covers it as well.

It generally takes more distance to take off than land and a considerable amount of speed is bleed off during the flair and subsequent touch down. If a plane touches down at the proper touch down point on a runway it may not have enough distance to accelerate and become airborne again by the other end of the runway. Further more you can complicate the situation with things like thrust reversers which, once deployed force you to commit to the landing.

The airport in question has a 5578 x 98 feet runway which is a solid size but chances are you were flying a plane on the smaller side. Generally the smaller the plane the less runway you need to land and take off so go arounds after touchdown are possible.

To directly answer your question, in some instances they do happen but they will be recorded as an aborted landing. In other cases (heavy crosswinds) you may have only one side of the mains touch (does that count as a touch down?). The runway length and aircraft size/performance are the main factors and there are so many combinations of that.

--Edit--

Since you have provided the make and model of the plane we can extrapolate a bit more. You can find the full specs here but lets take the the At TOW for 300 Nm - Max pax - 3,000 ft - ISA +10 - situation which is quoted at 4,626 ft. Take off speed at max load is 116 Kts (and you were landing so you were on the lower end of the fuel which means you were below max load even with full passengers). Likewise approach speed is 113 Kts. Some of this depends on the pilots precision but It should be (and obviously was) possible to touch down, full power, and get airborne again in enough distance on the strip. Sine you would only need to make up 3 Kts assuming he came in on the mark at 113. They would lose speed in the touch down but if they were on the throttles fast enough it would work.


What's the name for this part on a Cessna 172P?

It’s part of the interior trim, which has come dislodged from the fuselage side near the door.