texts: What can a passenger do if (s)he objects to the flight route?

texts:
Say that after a passenger learns of or views the flight plan, she opposes it (eg due to safety).

She could just refuse to board the flight and forfeit her ticket and costs, but are there less costly and dire and radical options? Despite being only a passenger, could she explain to the flight crew (plausibly via the cabin crew?) her reasons and thus request the reconsideration of the flight route?

Supplementary: I elucidate that I do NOT mean for her to compel or impress a specific route (replete with all the waypoints, VORs, etc...) upon the flight crew, but only a general concern for avoidance.

As an instantiation, if I were a passenger and had apprehended my flight to overfly Ukraine, even outside of the no-fly zone, then I'd remonstrate against it, in favor of a more northern one that would substantively avoid Ukraine.


texts: Why don't big airliners have bigger doors?

texts:
Reading this question I saw this picture in MikeFoxtrot's answer and noticed how easier it would be to board the plane using that huge door:

I understand that for single aisle planes you wold need to form a single line anyway, but for two aisle planes having a wide door could speed up the boarding process a lot.

So, is there a reason why it is not done? What is the limiting factor in the door size?


texts: Are modern fighter jets allowed to fly with an inoperative ejection seat?

texts: I'm wondering if a modern fighter jet (Eurofighter, JAS Gripen, F-35 etc.) is allowed to fly when the ejection seats are known not to be in working order.


texts: Does too big an angle of decalage make the horizontal stabilizer to stall?

texts:
This styrofoam airplane has two positions for stabilizer. When put in the upper one, the plane flies in a circle.
Is the stabilizer now stalled because the decalage angle is very big?What happens with the airflow over wing and stabilizer in this configuration?


texts: Have bi-wings been used without creating more drag?

texts:
As I understand from answers I've read here 1, 2, 3, biplanes create more lift with less wing span when compared to single wing aircraft, because the combined wings have greater surface area overall.

However this is usually at the expense of added drag as both wings are accelerating the same air downwards causing interference and creating inefficiencies. Also the wings commonly have supporting wires/structures between them causing more drag.

With that said biplanes do have some desirable characteristics like shorter roll response. I also realize when looking at how nasa calculates for the drag coefficient, wing aspect ratio is a major factor in their equation:

With this information it would seem to me if you could separate the wings of a biplane far enough apart that they don't cause much interference, you could possibly get a better performing aircraft with the same wingspan.

I almost imagine it being as simple as making the tail a full sized wing and giving each wing a thinner aspect ratio. However I've never seen this done before or even attempted. Is there a reason for this? Would the wings still interfere too much with each-other.


texts: How can I become familiar with flight rules specific to Canada when flying there from the United States?

texts: As a US licensed and trained pilot, I know I can fly into Canada, but are there are airspace rules that are different from the American system. Is there a Canadian rules test or conversion you can or should do, or should I just expect to fly in Canada by the exact same rules and procedures as in the United States?


texts: Does TRACON airspace override Class B airspace in terms of control authority when controlling approach or departure procedures?

texts:
This is a simple schematic description of Class Airspace.

My understanding is that Class B has strict rules, specific lower and upper altitude limits and requires clearance to enter. However, I have also come across the Standard Operating Procedures Manual for the N90 TRACON (ORDER 7110.1D), which designate the sectors of local airspace differently. Those also define lower and upper altitude limits. Clearly, the N90 TRACON overlaps with the Class B airspace around the JFK, LGA, TEB and EWR airports.

My confusion has to do primarily with this overlap. I was thinking that Class B airspace has to do strictly with terminal procedures (approaches/departures), that is, all take-off and landing procedures take place within this airspace.

However, I have seen SID and STAR procedures running over fixes located close to the airports, which define much higher altitudes than the Class B upper limits (around JFK and the above airports, the upper limit is 7000ft for Class B airspace, while lower limits vary).

Take, for example, the LENDY SIX ARRIVAL, of JFK airport. I read over the JENNO fix information: "Expect FL230".

What is this supposed to mean: "Expect FL230"? Will an approaching aircraft enter the procedure at a Flight Level of 23000ft or be at that flight level whenever approaching the airport at that fix point? How does Class B relate to these operations? I thought that approach operations take place within Class B but I am confused because the altitudes I see in SID/STAR procedures or the lower/upper altitude limits in the various airspace sectors of Standard Operating Procedure (SOP) plans* are quite different. It appears as if flights that approach for arrival, for example, are controlled before entering Class B (i.e. at higher altitudes) when inside a TRACON, e.g. N90.

*(I cannot link to an SOP Manual because they are intended for internal distribution, so I cannot find something official online, however, the information is pretty much like that document).


texts: Would in flight engine failure of the passenger jet be reported?

texts:
A passenger plane with two or more engines would probably land without big difficulties with one engine inoperative.

Would the passengers be notified, asking to take the brace position during landing?
Would such event have an accident investigation report?
Would this report later be available for general public, as are the reports of various significant air disasters?


texts: What is the airflow across and below an elevator?

texts: So when an airfoil creates lift. The air above the foil moves faster. This creates lower pressure in tip of the wing and relatively speaking higher pressure under the wing this create lift l. Along with meetings 3rd law of motion. You know it deflects aid downward the reaction is forcing the wing up. But how did this work with an elevator to my understanding. When the elevator goes up so the airflow across the top speeds up, so this creates low pressure. And the air below the elevator is relatively speaking higher pressure. But this would cause the elevator and tail of the plane to go down along with the pitch of the plane. But in realty when the elevator goes up,  the tail of the plane goes down and the pitch goes up. Same with when it goes down the the airflow below the elevator speeds up and become low pressure and the air above it is higher causes the tail of the plane to go down and the pitch up. But in reality when the elevator goes down the pitch also goes down. Really confusing, someone please help.


texts: What kind of identification code is this format? (AAA0000)

texts: From what I understand, an aircraft's registration number is its ICAO code in the pattern found here: Wikipedia: Aircraft registration, but I have seen references to aircraft using a 3-letter code (I'm assuming it's an airline code) followed by a 4-digit number. (Example: PAK0032) What kind of a number could that be?


texts: How does a remote pilot land a fixed-wing UAV?

texts: How does a remote pilot land a big fixed wing UAV, whose takeoff weight could be several tons and have to land at a airport with runways? I saw in the TV, these big UAV normally has on-board cameras and its remote pilot work at a station with displays. Is it manual or auto landing? If it is a manual landing, is it similar like manned aircraft pilots to set up the visual contact with the runway and determine the aircraft position in space relative with the runway based on their experience or they have some landing aided system? How they resolve the time delay issue that the image they see thru the onboard camera could be taken seconds ago?


texts: What causes a helicopter to autorotate farther?

texts: Which characteristics improve a helicopters ability to glide a farther distance in autorotation? Do these same characteristics reduce minimum decent speed in autorotation or is that affected differently? If so, how?


texts: Can confirmed passengers preview or request flight plans before the flight?

texts:
Can a passenger who has booked a flight wants to learn about the filed flight plan of their flight, prior to boarding it? I'm aware that the flight plan can change, or an aircraft can deviate from it, but still desire a rough map.

I'm aware of websites like Flightaware.com, but I think they only start tracking after departure?

For example, in the future, I'd want to see beforehand whether the aircrew decides to fly near a no-fly zone or dangerous area.


texts: What is the most recent turbofan engine that used steel for its bypass fan blades?

texts:
I haven't been able to locate any engines that use steel for the bypass fan. All sources suggest Ti and composites are used for blade construction. Apart from the weight steel could partially make up for it by offering a thinner blade, cost/ease of construction and more resistance to foreign objects.
The reason I ask is that I am trying to design a large ducted fan (800mm) that will be as cheap as possible to manufacture by using a thin sheet of stainless steel for the blade material. The cut to shape sheet will be pressed in a mold to achieve the designed AoA across the blade length and then a 3D printed airfoil will slide over it.


texts: Are there any proposals to continuously stream "black box" data?

texts:
After an aircraft incident, finding the black box is important to investigate the causes, because it contains a lot of valuable recorded data.  The process of locating this can take a lot of time, and perhaps in some cases it will not be found at all, or deliberately sabotaged.  Both problems could be mitigated by continuously streaming flight data through a satellite uplink — or, if there is no coverage, buffer the data until there is.

Do any aircraft do so, or are there any serious proposals to start doing so in the future?  What would be the largest obstacles?


texts: What are the issues involved in converting a quadjet into a twinjet?

texts:
As you are probably all aware already, the fewer engines you have, the better your fuel efficiency. That’s why the airlines are selling off their quadjet 747s and buying twinjet 777s. It's why they’ve already sold off their trijet DC-10s, L-1011s, and MD-11s and replaced them with twinjet 767s, 777s, and 787s. It's why the quadjet A340 lost out to the twinjet A330, and the quadjet 747-8 and A380 are struggling to sell while the twinjet 777 and twinjet A350 are selling like 737s. It's why the trijet MD-11 went over like a lead balloon compared to the twinjet 767, 777, and A330.

One obvious solution to the kerosene-guzzling-quadjet problem would be consolidation: replacing the two engines on each wing1 with a single, bigger engine (for instance, replacing a 747’s four JT9Ds, CF6s, RB211s, or GEnxs with a pair of GE90s, or an A340’s four CFM56s or Trent 500s with a pair of Trent 700s or GE90s).2  However, this generates the obvious problem that the wing might need to be redesigned for the different stress distribution of a twinjet, as opposed to a quadjet, design.  Still, the change doesn’t have to be large.  For instance, the A340’s wing is already almost identical to the A330’s; just deactivate the extra fuel tanks, chop off the bulge under the wing that was introduced to keep the airflow around the outboard engine from breaking the wing off, take away the outboard pylons, swap out the inboards for a pair of A330 engines, and you’re in business.

Yet, despite the massive efficiency advantage to be gained, there’ve been hardly any serious proposals to reengine quadjets into twinjets in this sort of way, indicating that there’re other issues that’re showstoppers for twinjetting a quadjet; what are they?

1: I’m leaving trijets (DC-10, L-1011, MD-11, etc.) out of this discussion, as converting one of those to a twin doesn’t involve any change in the number of lateral engines - just taking out the center tail engine and making the laterals somewhat bigger.  Also excluded are tail-mounted quadjets (VC10, Il-62), as these use conjoined engine pods (two engines per pylon), meaning that the two engines on each side could be swapped out for one bigger engine with little or no change in the stresses on the pylon and rear fuselage.

2: This doesn’t work for the A380, since not even the GE90 is powerful enough.  Sorry, A380!


texts: How is it safe and legal to land in parallel runways

texts:
How come it is safe and legal to land in parallel runways (for example, in SFO).

The planes are way too close, at a distance that would not, I assume, be according to flight regulations and safety rules during cruise flight.

At what distance from airport or below what altitude becomes it ok to fly like this?

Can airplanes also take off in parallel, or only land?


texts: Is airflow ever laminar in the boundary layer, near the wing leading edge?

texts:
I often see images of the boundary layer over a wing indicating the airflow is laminar over the first portion of the wing:

Transition from laminar to turbulent flow over the wing. Left: source, right: source

I was also told this cannot happen in a full-scale aircraft, as the Reynolds number involved are not compatible with laminar flow.

Would these pictures be misleading?

Is the flow laminar or not before the boundary layer is separated?
If so, what are the conditions that make a flow transitionning from laminar to turbulent?


texts: When an airliner gets lost, and receives warning shots from interceptors, how should the pilots react in order to save the aircraft?

texts:
In 1983 KAL007 was shot down by the Soviets, as it got lost due to navigational errors and entered restricted airspace. The Soviet interceptors reportedly fired warning shots "which were likely not seen by the KAL pilots", and after then they proceeded to destroy the airliner with an air to air missile.

So, let's suppose you are flying a commercial flight, when a military aircraft catches up to you. If your communication equipment wasn't malfunctioning, you would have already gotten demands to change course and you could have identified yourself, answered that you will comply, and could more easily avert the problem. For this case, let's suppose your comms are down due to technical problems.

You then see you are fired upon (how? smoke trails of a missile flying by? Tracers from guns whizzing past?). It is only then when you realize you got intercepted, and you suddenly realize they just fired warning shots at you.

What now? How could you maximize your chances of survival? I would guess you have to indicate surrender, that you will comply to any instructions, and that you mean no ill will. How can you do that without a working radio? If you just entered a country's territory, the most obvious way would be to change course to the shortest path leading out of that territory, but if you are deep inside, or you are lost, you might choose the wrong heading and make the problem even worse.

Is there a custom how a civilian aircraft can indicate "I yield, please don't shoot me, I will follow your orders!"? And, lastly, how would it differ between the incident happening in 1983 versus 2019?


texts: Recently, a small plane operating from a nearby airport suffered an engine failure on takeoff and crashed.  One of the hazmat responders dealing with the resulting fuel spill mentioned "a strong smell of Jet A", leading to speculation that the airplane had its tanks filled with the wrong fuel.  Would he have been able to distinguish Jet A from 100LL by smell?


texts: What are the flight rules for crop dusters?

texts: Crop duster aircraft operate much differently than most other aircraft. Are there special rules that apply to their operation? Specifically, are there rules about how close they can fly to structures, terrain, or vehicles?


texts: Is there a resource that lists what's outdated in "Stick and Rudder"?

texts: The classic book is awesome but I do know some of the terminology is outdated and perhaps some other things.  Is there a site etc. that keeps track of what's outdated in the book "Stick and Rudder" and what the newest equivalent terms?


texts: What happens if full thrust is applied at cruise altitude for 5-10 minutes on a 787?

texts:
What happens when you apply full throttle to the engines of a Boeing 787 at cruise altitude for 5-10 minutes?

Other than wasting fuel, what maximum speeds are reached?

Does that pose any danger or damage to the airframe?


texts:
When a planes maximum range is specified, is fuel [capacity] the only constraint or what else is taken into account?

Would it always or ever be the case that a greater fuel capacity will increase range?

Interesting long-flight story of 64 days in the air, but it doesn't get too technical: https://jalopnik.com/how-a-slot-machine-mechanic-flew-150-000-miles-over-64-5971433


texts: Why do helicopters typically have blades at the top?

texts:
This question has several great answers showing that it's perfectly possible for a helicopter to fly with its blades underneath the rest of the aircraft.

There are some obvious issues with having a helicopter's blades at the bottom, to do with proximity to the ground and being in the way when someone wants to get in or out of the helicopter. Is the answer that simple, or are there other reasons related to flight dynamics, manufacture, or something else?


texts: Is flap-asymmetry protection on airliners still active even on the ground?

texts:
On aircraft with flaps, a general certification requirement is that it must not be possible for the aircraft to suffer a loss of lateral control secondary to an asymmetric-flap condition.  This requirement can be satisfied in one of two ways (many aircraft go for both):

Demonstrating that the aircraft remains controllable without requiring exceptional pilot strength or skill, even if the flap(s) on one side are fully up and those on the other side are fully down.
Including a flap-asymmetry protection mechanism, which automatically cuts off power (hydraulic or electrical, whichever the aircraft uses) to the flap-drive motors if the flaps on both sides fail to move in synchrony.

The benefits of flap-asymmetry protection in flight are obvious; however, in addition to their roles as high-lift devices in flight and high-drag devices during landing and rejected takeoff, flaps are also used to allow airliner passengers and cabin crew to safely egress through the overwing exits in the event of an emergency evacuation on land1 (low-slung aircraft, like the 737 and most regional jets, simply have the passengers slide down the flaps to the ground, while taller aircraft have inflatable slides that deploy over the lowered flaps).  In such a situation, as optimal use of the overwing exits depends on the flaps being fully down, having flap-asymmetry protection active would be counterproductive, as a jammed flap on one side would prevent a properly-functioning flap on the other side from providing a good evacuation path, and flap-asymmetry-induced lift asymmetry is harmless on the ground anyways (it produces a rolling moment to one side or the other, but an aircraft is physically incapable of rolling to either side when on the ground unless it’s already at or very close to flying speed, because the ground is in the way).
Is airliner flap-asymmetry protection inactive when on the ground (like many other systems protecting against things that are only a hazard when airborne, such as stall protection [stickshaker/stickpusher] and GPWS warnings) to prevent it from hindering an evacuation, or does it remain active even then?

1: In the case of a water evacuation, the buoyant characteristics of most airliners are such that the water generally comes all the way up to the wings, making the degree of flap deployment, or lack thereof, irrelevant.


texts:
The traffic collision avoidance system has two versions, TCAS I and TCAS II.

I know for sure that TCAS I has a range of 40 nautical miles, but what is the range for TCAS II?


texts:
Aircraft use nav fixes as waypoints or reporting points along their routes. I have noticed some interesting combinations.

Some make sense, like LUCKI to LYNDI on the LYNDI arrival into San Diego International, known as Lindbergh Field, or KSINO LUXOR on the GRNPA arrival into Las Vegas.

Some are more interesting, like HIMOM KALME on the FRNCH arrival into Denver, or ASTAH LVSTA ADYOS on the ADYOS departure from Albuquerque.

Some get downright suspicious, like ITUNE MUSCC DWNLD on the LOWBO arrival into Albuquerque.

So my question is: how do these points get named? These combinations are memorable, but are they also allowed to be sponsored? Or is this a case of "Any resemblance to actual entities is entirely coincidental."


texts: How is drag created from wingtip vortices?

texts:
What is the reason for the drag due to wingtip vortices?

This question is about (general) performance, but doesn't answer the drag aspect.


texts: Do tower-controlled helipads have a standard naming convention?

texts:
Just wondering if anyone knows, or if it just depends on the airport.

Edit: This question is different than How does the FAA determine which format of location identifier to assign to an airport?.

My question is how the tower names helipads under its control at an airport, not how the FAA assigns an identifier to an airport as a whole. Runways use the runway heading. How are helipads named?


texts: Why is the front section of the Su-30 not aligned with the longitudinal axis of the body?

texts:
Please take a look at the picture of the Su-30 below. You will notice that the front section of the Su-30, from the nose to the canopy, is not in alignment with the longitudinal axis of the body. The canopy is raised vertically above the extended axis, and the front portion points downward.

In US fighter jets like the F-18 the canopy is not raised vertically above the extended axis and the front portion aligns with the axis from nose to tail.

So why is the front portion of the Su-30 shaped in that manner? Is it to give the Su-30 any advantage over aircraft that do not have such a front portion?


texts: What is this aircraft that has both piston and jet engines?

texts: A friend sent me this picture of a trimotor aircraft with what looks like two radial engines and a jet in the middle. He didn't know what is was and neither do I. Anyone recognize it?


texts: Why does stall speed decreases with increasing aspect ratio?

texts:
As I have found Cl(max) doesn't change with changing AR. Is it true?
Therefore stall speed which corresponds to Cl(max) and crit AOA must remain constant regardless of AR.
Where am I mistaken?


texts: Load factor and how does velocity affect it?

texts:
An aircraft initially flying level with a velocity of 130 m/s pulls
into:

a turn of radius 300m at constant altitude (i.e. a horizontal circle) with constant velocity;

a loop (i.e. a vertical circle path) of radius 300m, where the thrust is varied to equal the drag at any point (hence, any change in
velocity is entirely due to gravitational effects).

Determine the load factor for (1.) and (2.) when the aircraft is a the 90, 180- and 270-degrees position within the loop.

I have been trying to understand the question, however, I don't entirely understand what they mean. 90, 180 and 270 don't seem like banking angles and specially for part b, does it mean that at 90 degrees it has travelled 300 m vertically and its velocity will decrease based only on the gravity? Also, does the question assume 0 banking angle?


texts: Can different departure procedures have different transition altitudes at the same aerodrome?

texts:
Is it possible for operations and ATC to have different departures procedures with different transition altitudes at a single aerodrome? For example:

SID RWY11 with a transition altitude of 2,000 meter
SID RWY29 with a transition altitude of 2,500 meter


texts: How do fighter jets stop pitching motion after a elevator deflection?

texts:
I'm working on a flight simulator , In which the jet has only ailerons , rudder , and two elvators at the back . When I nose up my aircraft via elevator deflection , it just keeps pitching up ( even when I let go of elevators and let them back to neutral)  , after going pitch max , it starts pitching in opposite direction and then back and forth . These oscillations take lot of time to die out and the motion  of my jet is like a sine wave going forward .
I'm using real forces of lift and weight on the aircraft body.
So my queries are ,

How does a fighter jet locks it's nose at a particular pitch angle ( the moment the pilot let go of the deflection) and  does it so smoothly and slowly , that it's possible to aim at whatever direction you like and hold it there , even when flying at 600KM/Hr.
Because when I let go of my elevators , entire plane just goes into oscillations and it becomes tedius task to focus on killing those oscillations .
A cheat that I'm thinking of is , let's say pilot makes +30 degree deflection to elevators and let go , then the computer will immediately put the elevators to -30 degreee deflection . This will exactly cancel out the rotational momentum built up by the initial deflection .  But in real aircraft , it will take time to put the control surface in opposite angle . So how do they do it so quickly .
This person claims to be using a PID controller for pitch damping . How does a PID controller acount for the inherent delay in the actuators of control surface . Let's say controller decides an +10 degree is needed this moment to keep the aircraft stable at the current pitch , but the hydraulics will take their own time to put the control surface at that angle , by that time aircraft will have moved even more from the required stable position .

I know I'm asking too much in a single question . But I've been stuck on this problem for so long that only more and more problems have accumulated in this time .


texts: What do these temperature data listed in the EASA Type Certificate Data Sheet mean?

texts: Could you tell me what is the Maximum Permissible Indicated Turbine Temperature (ITT) and the ambient limit temperature for sea level static thrust?


texts: How does fuel get to the engine during acrobatics?

texts: Given that during acrobatics, extreme G-forces may be impressed upon the fuel tank, wouldn't it make it somewhat difficult for fuel to get to the fuel pump while it's being pushed against a specific direction for the duration of the stunt? Is the solution just not to do the stunt long enough to starve the engine of fuel?


texts: What is the best strategy for landing when a flock of birds is on the runway?

texts:
At a controlled airport, the tower advises large flocks of small birds at the approach end of the runway.

I'm in a small trainer aircraft like a Cherokee or Cessna 172. Should I request to land the other way (Rwy 9 vs 27), proceed as normal but just expect them to only be a distraction?  What are the best options here?


texts: What general aviation single-engine piston pressurized airplanes are there?

texts: Finding a general aviation single-engine piston airplane that's pressurized is a bit rare. What airplanes that meet these specifications have been produced? Also, which ones are still in production?


texts: Is it possible to takeoff without flaps extended?

texts:
related questions:

landing wihtout flaps
takeoff with full flaps

My question focus on passengers jets (goes from Embraer E-jet family to  Airbus A380). I don't know why pilots would attempt to takeoff without flaps but lets say they will.

Considering all the other parameters are good enough (no crosswind, long runway, aircraft light enough,...) and the pilots are aware of this unusual takeoff configuration and adapt their action accordingly (including increasing $V_r$ and $V_2$), is it possible for any passenger jet to takeoff and stay airborn (not like the flight spanair 5022) without extending flaps?


texts: Which Aircraft Models need a Tripod Jack for tail support at airport?

texts:
Which are the aircraft models that need their tail to be supported by a jack when empty?

Wikipedia says this:

  Aircraft Tripod Jack

  They are used to support a parked aircraft to prevent their tail from
  drooping or even falling to the ground. When the passengers in the
  front get off an aircraft, the aircraft becomes tail heavy and the
  tail will droop..... When needed, they are tugged to the tail and
  setup by manpower. Once setup, no supervision to the jack is needed
  until the aircraft is ready to leave.

Are there even commercial airliners that need to be supported this way every time they load / unload? Sounded like a lot of work for ground staff. Was this a legacy equipment thing or still in use today?

https://en.wikipedia.org/wiki/Ground_support_equipment


texts: Does the angular momentum of a jet engine affect aircraft performance?

texts: I am interested, do jet engines have angular momentum? And how does such momentum affect airplane stability?


texts: Can a pilot use their GPS/FMS to fly a VOR or NDB approach?

texts:
GPS is more accurate than a VOR or NDB signal.  Can we use a GPS to fly a VOR or NDB approach from the initial approach fix through the missed approach and hold?

I know there are two types of approaches that deal with GPS and VOR/NDBs:

NDB RWY 35L (KCOS RWY 35L) without GPS in the title
VOR or GPS-A (KGUC VOR or GPS-A) with "or GPS" in the title

I'm specifically asking about the first type or approach without the wording "or GPS in the title.


texts: Why would a plane have these lights on the bottom?

texts:
I'm trying to convince someone this is not a UFO but probably just not a commercial plane. What would be the reasons to have the colors of the plane lights like this?
The person is claiming because it was inaudible, seemed rather large, and had blinking lights that it is a UFO. Are there any reasons for this as well?
Coordinates: 36.841900,-87.673600 Kentucky
Time: July 4, 2020, 12:29am


texts: What is the format specification for Avidyne R9 flight data?

texts:
The Avidyne R9 records flight data five times per second and can export it for later analysis.

I'm interested in parsing this data and exporting it to Google Earth / X-Plane for visualization.  Cirrusreports already does this, so I know it's possible.  It would be easier, though, if there was a spec already out there.

Is there a specification for the Avidyne R9 flight data file format available, preferably online?


texts: Why does the SR-71 Blackbird sometimes have dents in the nose?

texts:
On many pictures (maybe on most of the pictures) part of nose looks hammered or slightly smashed, or bent.
Please note these 2 symmetric dents just behind nose spike:

source

source

On other pictures these dents are missing:

source

Why? Is this a feature or damage?


texts: What regulations govern UAV lights in Australia?

texts:
I'm a member of a student aviation club at my university, and we're working on a UAV. The club member working on our drone's power supply system has designed a system that uses externally-visible LED lights for displaying system errors to allow for visual inspection of the functionality of our systems, and to allow for us to determine if something goes wrong in flight by looking at it from the ground.
However, I'm uncertain if this would comply with CASA regulations regarding aircraft lights; if it isn't allowed, the current plan is to simply cover the them with a cowling prior to takeoff so that they won't be externally visible. Doing a Google search, I found this page on CASA's website detailing requirements for mandating certain navigation lights, but it doesn't say anything about restricting them. It seems fairly likely that red, green, or white lights would be prohibited to prevent confusion with the navigation lights, but would amber lights be allowed?


texts: What do we mean by taking the lowest of ZFW; TOW and LW to determine the maximum takeoff weight of the day?

texts:
Firstly, I understand that the maximum permissible takeoff weight can be limited by landing weight because landing weight plus trip fuel gives us one take off weight. We obviously do not want to be taking off with any extra fuel which we can not burn to allow us to be under the MLW upon reaching the destination.
Secondly, I understand there is a structural limitation which can not be exceeded.
I can not get my head around how we are limited by the Zero fuel weight to determine how much should be the maximum takeoff weight for a given day?
I am specifically asking with regards to Airbus 320 wherein MTOW is 77t, MLW is 65t and MZFW is 62.5t


texts: How is training for an SIC type rating accomplished when an aircraft is two pilot certified only?

texts: For an aircraft which is certified for two pilots and a simulator doesn’t exist, how does someone go about receiving the required training for an SIC type rating without having the type rating already, since two type certificates pilots are required for the operation of the aircraft? Furthermore, how can the pilot in SIC training log anything to meet the experience requirements for the SIC type rating when you cannot log anything for a type in which you are not rated (category, class, and type), much less act as a required crew member? This question is specifically in regard to FAA regulations.


texts: What does "maximum update interval" mean for Mode S GICB registers?

texts:
Transponders have registers for Mode S data and configuration. These registers are updated periodically to provide Mode S services such as ADS-B Airborne Position squitter.

DO-260B and similar documents have Register Allocation Tables that states maximum update intervals for each register(if applicable).

But there is also a register timeout mechanism that states "if a register can not be updated within twice the maximum update interval, it shall be zeroized".

So, what happens if certain register is updated at every (1.5 * maxUpdateInterval) ? Are these maximum update times mere suggestions or is there another rule that forces us to update registers at most maximum update interval?


texts: What are Electro Hydraulic Servo Valves and Solenoid Operated Valves?

texts:
What is Electro Hydraulic Servo Valve (EHSV) and Solenoid Operated Valve (SOV)? Also what is the difference between these two valves?

Basically, these two are used to control the hydraulic fluid in actuators. I am working on a aircraft program where SOV are used in Aileron, Elevator & Rudder actuators while EHSV are used in Multi-Function Spoilers [or just spoiler]. I think someone explains these two valve basics would provide me the reason for the selection of these valve to control the hydraulic actuators.


texts: Who has the higher authority, the pilot in command or ATC?

texts:
I'm sure many people have heard about the communication between a Delta flight 2244 and Atlanta tower being on news today.

When the Controller informs the Pilot he is on a wrong taxi-way, things get a little heated up.

Regardless of who was right who was wrong, there were many lives involved (i'm sure they were not put in danger) but then who takes precedence in such a situation?

Can the controller tell the aircraft to stop dead in its tracks or turn back to the hangar for violating his instructions because there are other planes coming in to land and this can become a little dangerous?

Note: I am fully aware that no one was close to danger and lives were not at risk, but still pilot did worry that there is another plane coming down.

Was the pilot right in saying

  We'll taxi out there any way we want when you tell us to.

For those who missed. Here is the whole story

Note

Please note that this reporting on that article is misleading. It is about taxi clearance and not landing on a wrong runway, However I have no control of what reporters write in their articles. The transcript itself is clear.

Hear the original ATC audio here


texts: Is defacing the airline logo of a wrecked airplane illegal?

texts:
I was listening to episode #25 of the Hello Internet podcast where Brady Haran mentioned that it's not unheard of for airline employees to rush to their own airplane's respective accident scene to deface the logos and registration numbers painted on the airplane's wings and fuselage. This is apparently done to reduce the damage to the airline's reputation. Below is an picture of the same from an alleged account of Thai Airways defacing the logo on a crashed (but still very intact) airplane.

So is there any law regarding whether this can be done? Could defacing the logo end up hampering the air crash investigation?


texts: What is the weight of the fuselage (only) of the Boeing 747?

texts: I'm wondering about the weight of the Boeing 747's fuselage.


texts:
I was looking at aerial imagery of various airports and noticed how some have a large number of runways (4-6), while others have a small number.
Specifically, I noticed that Heathrow (LHR) only has 2 runways, but it is the busiest airport in Europe by passengers. In comparison, the following busiest airport have many more runways (Paris Charles-de-Gaulle (CDG) has 4, Amsterdam Schiphol (AMS) has 6), but fewer passengers.

Why do some airports have more than 2 runways, when LHR can get by with 2?


texts: What were the L/D ratio of the A-90 Orlyonok at its different operational atlitudes?

texts:
The A-90 Orlyonok was designed to operate in ground effect (altitude significantly lower than its wingspan). If I understand correctly, when in ground effect, the L/D ratio is better due to induced drag being lower. Thus, I imagine the L/D ratio of the A-90 is high when cruising near at low altitude, but I failed to find any figure *. Moreover, according to Wikipedia, this aircraft have a ceiling of 3000m (not really in ground effect).

I'm interested in the performance differences between flying at ground effect altitude and at almost 10000ft AGL.

What were the L/D ratio of the A-90 Orlyonok at its different operating altitudes (when in ground effect, at its ceiling, and at any other altitude it would spend time flying at)?

* I only find a paper that states GEV in general have a L/D ratio of 23 without saying if it applies to the A-90 nor at what altitude this L/D ratio is found


texts: How frequent are unpublished holding patterns outside general aviation?

texts:
Flight regulations say that ATC may put an aircraft in a holding pattern, which is not published in the charts but I couldn't find any such case in FlightAware.

I have been searching on the Internet but I think I found almost only some information about flying uncharted holding patterns in general aviation and that it is something the ATC would like to avoid.

I'd appreciate any information on how often (and when or where) these uncharted holding patterns are used outside general aviation.


texts: Is it legal to use a home-made Airband radio receiver in the United States?

texts:
I work at a local small airport (very small, if we get more than about 10 or 15 airplanes taking off/landing it's a "busy day") and I mow the runways (we have multiple grass ones).

Because of the visual obstructions of the tractor's cabin that I use I have to be even more careful than normal to check for in-coming planes and so I started looking into getting an air band radio for the tractor. However, they can be fairly expensive - not something I'd invest in unless I absolutely had to - and so I started looking into making my own.

I'd figured this was possible because I'd occasionally picked up communications on a cheap radio I had around my house (I live quite close to the airport, about a 5 minute bike ride). So, I went searching, and sure enough - this is a thing that is possible and has been done.

I found this post on Electrical Engineering.SE, Modify an AM/FM radio to an airband receiver, describing basically what could be done; and then this video done by MAKE, Weekend Project: Aircraft Band Receiver, showing it actually being done to cheap transistor radio.

Now, what I'm wondering is, is this a legal thing to do - or does the FAA have regulations on this sort of thing?


texts: Is there a forced retirement age for Part 135 pilots?

texts: I know that international Part 135 operations have a set retirement age of 65, however if one was to stay within FAA jurisdiction is there a set retirement age for Part 135 operations?


texts: What types of maneuvers increase the load factor on the aircraft?

texts: Out of turns, stalls and climbs, which of the basic maneuvers increases the load factor on an airplane as compared to straight and level flight?


texts: After submitting a NASA ASRS report, it is returned to the submitter along with the tracking number.  For how long should that packet be retained (in case it is needed during an FAA enforcement action)?


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

texts:
What is the difference between centre of pressure, aerodynamic centre and neutral point?

At this link, there is an image used to explain the answer, but not much has been spoken about it.

I understand that the disturbance was caused by either the CG moving too ahead or too rear, or the CP moving forward of the CG. I would like to know that in the given image, how did the aircraft hold the disturbed orientation ?
Was it perhaps by mechanically shifting the CP back again using some device ?
Thanks in advance.


texts: The wing has a pressure gradient along the AB direction, is there a pressure gradient along the CD direction?


texts:
Is there a legal definition of a "cycle" on a jet engine?

We must log the cycles, and some maintenance is determined by cycles.  From my understanding, this is partially because of the thermal dynamics of an engine cooling and then reheating, and partially because full takeoff power is used.

The "usual" time that you log a cycle is when an engine is started and the aircraft then takes off (using full rated takeoff power), but what about unusual situations like:

Engine shutdown and restarted in flight
Engine started, aircraft takes off, and then returns for a low pass or a touch and go:  Would this be two cycles (does it depend on the amount of power used during the touch and go?)?
Engine started and then shut down without a flight


texts: Could injectors be used as an alternative to turbopumps in jet engines?

texts:
Could injectors be used instead of turbopumps in aeroengines? Are there jet engimes that already use them?
https://en.m.wikipedia.org/wiki/Injector


texts: Is "balanced field" defined with or without an engine failure?

texts: I’m wondering what exactly means a balanced field in terms of aircraft performance. From what I know it means that TODR=ASDR, also it is minimum field length required. But I do not know whether this TOD and ASD are with or without engine failure.


texts: Why do we need a negative derivative of the pitching moment? restoring moment should be enough?

texts:
I am wondering why I read everywhere, that for static stability (longitudinal) the slope of the lift coefficient has to be negative.
Imagine a curve (cm= coefficient of moment , alpha = angle of attack) like the one on my picture. In the trimmed condition where c_m=0 : when I have a an increase in angle of attack, it should be enough, when c_m is negative, because I will always have a restoring moment. The more negative it is, the stronger the restoring moment.
So also when the slope is increasing, I am still in the negative area like in the red area of the picture with a restoring moment.
What I can imagine: such a slope of cm over alpha for a whole aircraftwill maybe not exist?
Thank you for your comments and thoughts


texts: Do crew rest seats count towards the maximum allowed number of seats per flight attendant?

texts:
We work as flight attendants on a 737-400. We were taught that we must have one FA per 50 seats. Normally our planes have 150 seats and with three FAs we have no issues.

Recently the seat configuration was 152 seats. We called our company and told them that we were not legal to work like that since there were only 3 of us. They stated that 2 seats were for "crew rest" and that we were legal as long as we didn't seat passengers in those 2 particular seats. Is this correct? No one ever said anything said to us about these crew rest seats.


texts: Is it safe to fly on airplane with lithium batteries in cargo hold?

texts:
Lithium-ion batteries have the tendency to go on fire.

I checked baggage policy of European low cost carriers (easyJet, Ryanair, WizzAir), and while spare batteries are banned from cargo hold, it seems that batteries in devices are allowed (also hand baggage could be placed in hold if there is no place in cabin).

If spare batteries are dangerous, aren't batteries in devices too?

A few incidents happended when lithium-ion battery exploded, and the fire has been extinguished by cabin crew.

Such fire could also happen in cargo hold. What's happens then? I've seen people question the ability of halon fire suppression systems to extinguish lithium battery fire, because it works by blocking oxygen from fire, while lithium-ion batteries do not need oxygen to burn:

  Halon basically works by displacing the oxygen that is feeding the
  fire - and won't work when the material that is burning can provide
  its own oxidizer. Li-O batteries fall into that category, along with
  things like ammonium perchlorate (used to make solid rocket
  propellant), gunpowder, and oxygen generation canisters. Once ignited,
  they will continue to burn until the fuel is exhausted....
  (http://www.pprune.org/australia-new-zealand-pacific/538637-melbourne-airport-737-cargo-hold-fire-poss-due-lithium-ion-battery-2.html)

Also this:
https://batterybro.com/blogs/18650-wholesale-battery-reviews/19673027-plane-safety-systems-are-confirmed-to-not-stop-lithium-ion-battery-fires

On the other hand in comments to this question: What safety differences exist between carrying laptops in checked versus carry-on baggage? people suggest that it will keep fire from spreading until battery extinguishes on its own.

Moreover checked baggage is not always handled gently by airport employees, which can damage electronic devices - and batteries in them, which makes them more likely to catch fire.

For me it seems like any airplane carrying electronic devices could go on fire at any moment, and each flight is as safe as the batteries it carries. On the other hand aviation has stringent regulation about using electronic devices on board out of fear of interfering with airplane systems. I guess that if lithium batteries were so dangerous as I think then they would be banned from cargo hold.

So is airplane crash due to lithium battery fire a real danger, or do I worry too much?
(I guess I'm a little nervous - I'm going to fly a third time in my life so far.)


texts: What is a good place to start learning about pulse jets?

texts: I'm a student who is curious about designing his own pulse jet engine, I am wondering if there are any schematics designs, notes, and other related materials I could/should study to learn about these engines. Where can I find such things and what is a good place to start?


texts: How to keep a Garmin GTX330 turned off when powering on avionics?

texts:
There seems to be an option in the GTX 330 settings that keeps to unit from powering on when receiveing power from the power system.

I flew in two different airplanes and one immediately powered on the transponder, the other one keeps the transponder turned off, until I press ON.

Looking thru the Pilot's Guide and Installation Manual didn't give me any clue.

Can someone help? Seems like an undocumented feature.


texts: Was the March 2019 Rafale jet ejection incident investigated?

texts:
This is one of the wildest stories I’ve ever heard of.  Then again, this is CNN’s disaster-a-minute-for-ratings kind of reporting.

https://www.cnn.com/travel/article/france-fighter-jet-ejection-scli-intl/index.html

A group of French co-workers organizes a ride for a 64 year old fellow worker in a Dassault Rafale jet fighter wherein the man panics during flight and pulls the ejection handle, bailing out mid flight and landing in a field near the German border.

I stare completely baffled at this as to

How these people managed to convince the French Air Force to let this man ride back seat in a jet fighter
without any kind of familiarization or ejection seat training and
Nobody noticed the guy’s level of discomfort during pre-flight taxi or even takeoff?

Was there any in-depth investigation to the incident and if so, what was determined to be the root cause(s)?


texts:
I was having a discussion with my friend about equilibrium condition in flight:

Scenario:
While going in straight and level flight, say I reduced my airspeed by 30 mph.
At the same time keeping the airplane's attitude strictly the same as before
(doing whatever it takes to keep the nose where it was before).

Reducing the speed means, the aircraft develops less lift: Aircraft is supported by less pounds of lift force (meaning which lift is less than weight)

What happens next? (imagining that pilot does not nose down)

My take:
1. Since weight > lift, aircraft drops attitude and falls like a stone that was dropped in midair unless the nose is down.

My friend says:
2.  The airplane finds new lift. This sinking motion creates lift
for aircraft. But it will not maintain straight level flight but descends. It will be a steady descent not accelerating descent. (not like a stone falling out of sky). He says this is called power descent

My question is:

1) Who is right here

2) If my friend is right, if aircraft can find lift after it descends (which means it found equilibrium) , why can not it maintain straight and level flight. And what exactly caused it to find new lift? Has angle of attack changed?


texts: What are the aerodynamic implications of different conditions with the same Mach number?

texts:
At a particular Mach number, a fluid behaves similarly, but many other conditions could be different.

For example, an aircraft flying at Mach .85 at a low altitude will be in denser, warmer air, and actually flying faster, than the same aircraft flying at Mach .85 at a high altitude.

What aerodynamic differences (if any) will the aircraft experience between the two conditions?

As far as flight aerodynamics is concerned, which of Mach number, true airspeed and indicated airspeed are most significant, and when?


texts: What's the standard print size for a sectional chart?

texts: I'm checking out the Dallas sectional in digital form for my own amusement. The image, in TIFF format, is massive. I wonder, if you buy one of these in printed form from the FAA (or your local GA office), what would be the sheet size of the map?


texts: Vertical and horizontal separation between cruising and climbing aircraft

texts:
I was recently a passenger on a commercial aircraft at cruise altitude when I noticed another aircraft just reaching its cruising altitude while crossing our flightpath from below, at what looked like a very close distance.

I looked up the two flights (LH491, AC172 on Nov 10, 2018) on Flightradar 24, linearly interpolated the following values in Excel to roughly 2-3 seconds resolution, and calculated the great circle distance between the coordinates:

AC 172 was heading 106° at the very end of its climb to FL 350. LH 491 was heading 51°, cruising at FL 350.

The smallest horizontal separation by my calculation was about 3.67 nm (at 1300 ft vertically). When we reached 1000 ft vertical separation, that distance was about 4.7 nm.

To my understanding, aircraft at these altitudes should always have a separation of least 1000 ft or 5 nm.

Not being an aviation professional myself, could someone please help me understand what was happening here?

I'm sure there must be a duplicate question, but I couldn't find one that involves both the vertical and horizontal components.


texts: Why does the auto brake panel on an A320 use "lo", rather than "low"?

texts:
Is there a specific reason that Airbus chose to shorten "LOW" to "LO" for the lowest autobrake setting?

Wouldn't it be more consistent to use three letters for each setting?


texts: EASA part 66 licence conversion to the Japanese version?

texts:
I am looking at a job proposal in Japan. I need to transfer my EASA Part 66 engineers license to the Japanese version.

Can anybody offer any advice on how I would achieve this?


texts: How do the linearised equations of motion work?

texts:
I am reading this book: "Flight Dynamic Principles" by Cook, second edition.
You can read it here:
https://aerocastle.files.wordpress.com/2012/04/flightdynamicsprinciples.pdf

First, go to the page 76, read the sentence:

  Further, the only significant higher order derivative terms commonly encountered are those involving $\dot w$.

Why is the only $\dot w$ involved here? the $\dot u$ and $\dot v$ have the same roles, huh??

Second, same page 76, section 4.2.3, the sentence:

  The assumptions applied to the aerodynamic terms are also applied to the control terms thus, for example, the pitching moment due to aerodynamic controls may be expressed.

And you can see the equation (4.32)

it is totally different from aerodynamics terms equation..why is that?. Why are moments not dependent u, v, w, and p, q, r like aerodynamics terms.

Lastly, look at the example 4.2 at page 80, what is the meaning of this example? where do the values of dimensionless longitudinal derivatives at page 81 come from? What are they? The book said seeing the appendix 2 at page 413. Now go to the page 413, where do these multipliers come from?


texts: What is the power rating of the ground power unit for Bombardier Dash 8 Q400?

texts:
I am researching about ground power units for aircrafts and I need the power rating requirements (kW/kVA rating) of ground power units to supply electrical power to Bombardier Dash 8 Q400 and Embraer E145.

I know that aircraft need 115VAC and 28VDC, but I need the power rating of the GPU in kW or kVA like an Airbus aircraft needs a minimum of 90kVA GPU.


texts: What is that CFM56 with a toothed exhaust on an A321?

texts:
I stumbled upon a wikimedia picture and I saw something that I have not seen before: a CFM56 with a toothed engine exhaust. Can someone explain to me what engine variant that is?

Source Author: Konstantin Nikiforov CC-BY-SA-3.0


texts:
What happens during a solo checkride and how do I put myself in the best position to be successful?

Also, why is it 2 hours? Is there a reason it would be longer than the flight you're used to if you usually fly 1.5 hours?


texts: Where is the wing sweep angle measured from?

texts:
If you look at a 747 planform wing you see something like this:

In several aerodynamics and aircraft design text books they use the wing sweep angle as an important parameter to measure the wing efficiency at transonic velocities, but they don't specify from where they measure that angle. Even I've seen wings with double leading edge angles.


texts: What is this plane with its thick cockpit?

texts:
Today I saw this unusual plane while going to work. I'm in France, near Paris. It flew at a rather low altitude, even if I can't tell precisely - I noticed the low altitude because of the loud sound.

We have an airport at 20km, the Charles de Gaulle Airport (CDG).
The plane was going towards South-West, probably directly departing from it. It came from this direction.
I was in the place named "La Défense", a district in the west of Paris.

I did make an outline sketch but it's not very precise :

It looked like a very small airliner; what sparked my attention was the front of the plane (the cockpit, very probably), which was thicker than the fuselage, making it look like some sort of hammerhead shark.
The wings were posistioned more towards the back of the fuselage than usual, but I can't remember if they were straight or oriented like usual.
As well it had a T-shaped tail.

I'm not very knowledgeable about planes but I have a some interest and I have never seen one like this.

I'm curious because it really looked unusual to me and that cockpit was funny.


texts: Do large Airliners use full thrust when reversers are deployed?

texts: Do large and heavy Airliners, Jumbos and Super Jumbos wide bodies included use full thrust for braking when reversers are deployed?  What is the thrust setting?


texts: What is the relation between flap setting and aileron droop on the A350?

texts:
The A350 has a aileron droop function, which is linked to the flap setting. In contrast to other aircraft with aileron droop, the  A350s ailerons do not droop when the flaps are fully extended.

I would like to know why the ailerons don´t droop when the flaps are fully deployed, and if possible what the scheduling for the aileron droop looks like in relation to the selected flap setting.


texts: Are there any electric ultralight aircraft?

texts:
Are there any electric, FAR part 103 aircraft?

FAR part 103 aircraft are unique in that they don't need a license to fly.


texts: Where is Transport Category aircraft defined in CFR 14?

texts:
Commuter Category is defined rigorously,

https://www.law.cornell.edu/cfr/text/14/23.3

But I was unable to find an equivalent definition for Transport Category in the regulations (not Wikipedia or the FAA website, haha). Nor was I able to find anything like "if requirements not met for Commuter, then the vehicle is in Transport Category."

Could somebody point me in the right direction?

Thank you.


texts: Can I fly under a solar eclipse to lengthen its effect?

texts:
There is going to be a solar eclipse in 2017 and I thought it would be cool to fly along its path to make it longer than the approximately two and a half minutes you would see on the ground.

Is this a bad idea?

Should I go to fast or slow for the solar eclipse?

I think it would be fun to fly during the solar eclipse, even if I can't keep pace with it.


texts: Does hypoxia affect pilots differently from people on the ground?

texts:
In my experience, many people don't have serious problems camping, skiing, hiking or doing other physical activities at 12,000 feet (3,600m).  We may get tired easily, and be out of breath, but we still function physically and mentally.

But for pilots (who aren't exerting themselves physically), hypoxia is a much more serious problem, e.g. see this article. Pilots aren't involved in heavy physical activity the same way mountaineers are, yet 91.211 requires O2 for periods as short as 30 minutes.

Is it accurate to say that hypoxia hits pilots harder than campers for some reason? Is there a clear reason why?


texts: Can aviation HF radios receive while transmitting?

texts:
I was listening to Gander Radio on HF at 5616 kHz today and I've noticed that operator at Gander would often start transmitting reply before the airplane finished transmission, as if trying to interrupt radio operator on the plane.

To me, this was very unusual behavior. From what I've heard and from what I concluded after listening to frequencies, it seems that HF radios in aeronautical mobile service work in traditional simplex mode, so crew normally crew wouldn't be able to hear the part of transmission send before they stop keying their radio.

So this brings me to these questions:
Are aviation HF radios capable of receiving while transmitting? If so, how?
Or if not, what's the point of Gander stepping on the plane's transmission?


texts: What is the correct phraseology for changing the runway of a landing clearance?

texts:
In the liveATC clip on this YouTube video, an American Airlines 767 arriving at SFO (San Francisco International) had been cleared to land on 28R, but, apparently while already on final, was told to switch to 28L.

The initial clearance given as

  American 2293 Heavy, San Francisco Tower, Wind 210 at 18, Caution Wake Turbulence, Heavy 767 mile-and-a-half final, Runway 28 Right, Cleared to Land.

which was read back, as per the usual. However, the Tower later sent the following transmission:

  American 2293 Heavy, Change to Cleared to Land Runway 28 Left

which the pilot read back as

  28L, Cleared to Land. American 2293 Heavy.

However, the pilot was seemingly too focused on flying the final to notice that the runway assignment had changed between the clearances and continued flying final to 28R, nearly resulting in landing on top of a United jet that was subsequently cleared to line-up-and-wait on 28R. Fortunately, the United pilot noticed the big 767 flying towards him and exited the runway on the other side instead of lining up. Tower then instructed American 2293 to go around.

It seems to me that the phraseology used to change the clearance here is too close to sounding like the controller is just repeating the initial landing clearance, rather than directing a busy pilot's attention to the fact that he was just told to change runways while apparently already flying final.

My question is: Was the phraseology correct for this change of the clearance? If not, what is the proper phraseology?

Given that this was in the U.S., I'm looking for FAA phraseology.


texts: What is the purpose of the "Mirror-Thing" over the Mig-29 Cockpit?

texts:
I noticed that some Mig-29 Fighter Jets have a little mirror-like-thing over the cockpit. I can't imagine a possible usage from it (If it's really a mirror).

Here's a picture from Wikipedia:

As you can see on the following picture, not every Mig-29 has this thing:

What is this "Mirror"-like-thing supposed to do?
Why can't I find it on every Mig-29?
When is this thing used? In combat, training etc.?
How does it help the pilot / trainer in flight?


texts: I found the best glide speed of cessna 152 is 60 kts. My question is why it is not more or less than 60 kts? What are the factors upon which the best gliding speed is determined?


texts: When two pilots are required for a private aircraft, is it a requirement for the PIC to be ATPL?

texts: After discussion on who could be a captain, I would like to clarify, is having ATPL a requirement for PIC on an aircraft that requires two pilots to fly?


texts: Does the compressor stationary vane have stagger angle? ( stagger angle is the angle between chord of the blade or vane with engine's longitudinal axis )


texts:
Recently there was a mishap at South Lakeland Airport in Mulberry, Florida where a Cessna 170 collided with a skydiver. Luckily all involved suffered only minor injuries. As far as I know, skydiving in Germany must be NOTAMed, is this not the case in the US?

The incident was caught on a series of stills:


texts: Why are Vertical tails generally tapered?

texts: I'm just intrigued to know why the vertical tail of a majority of aircraft is tapered? Is it due to aerodynamics, structural design or due to some instrumentation or multiple other reasons?


texts: Can one become a scheduled airline pilot with just one functional eye?

texts:
I was reading about TACA Flight 110 that amde a successful emergency landing on a New Orleans levee and I found out that the Pilot in Command was blind in one eye.

Just curious, under current FAA rules would such a pilot be able to get the Airman's Medical Certificate needed?

There's a related question, but that only discusses getting a PPL and even there the responses are quite skeptical. And here we're talking about a CPL, or more accurately a type-certified ATPL.

Have regulatory regimes become stricter? Even if the rules allowed it, would risk-averse/litigation-averse airline companies allow it? Are there other cases known?


texts: What is the breakout by service branch for FAA ATC specialists with military backgrounds?

texts: For young people interested in air traffic control careers with the FAA and who view military service as providing a boost toward that goal, which branches are most and least likely to get them there? In other words, how do the branches of the U.S. armed forces compare by headcount of ATC specialists working for the FAA?


texts: Small aircraft performance enhancements due to winglets?

texts: I'm seeing some Beechcraft Barons with winglets.  Do these improve performance and, if so, by how much?


texts: Does Daylight Saving Time affect local airspace?

texts:
Only some countries use Daylight Saving Time. In Canada, some provinces use and don't use DST (such as Saskatchewan). However, in remote and local regions where this is not observed, what would happen?

What happens when areas that do not observe DST are controlled by areas that do. (Cleveland controls parts of Southern Ontario). How does this affect local airspace? Does it affect global airspace as well? What are the safety implications? How does it affect Air Traffic Controllers operating these different spaces?


texts: How do radio communications work en-route for intercontinental flights over the oceans?

texts:
What is the altitude one must reach in order to communicate with the ground?
Is it possible to talk to ground via radio flying over the oceans?
How to know the exact position of an aircraft over the oceans?


texts: Do aircraft automatically send a message to the ground if there is a catastrophic failure?

texts: For example, if there is a engine failure, it will be displayed on EICAS as a CAS message. As per my knowledge, the pilot will initiate the contact with any ground station nearby for guidance to land safely. Iis there any equipment in the aircraft to send the distress automatically when there is any major failure?


texts:
Airport ramps are close to level, not inclined.

What is the history and etymology of this aviation term?


texts: What are the best tips for circuit practice with strong crosswind?

texts:
I am a student pilot with around 30 hours of flying right now. I am yet to solo and I am currently in the final stages of closed circuit practice.

Overall, my pattern work is good. However, maintaining the perfect "rectangular" circuit gets tricky for me when facing strong quarterly crosswinds (10 knots gusting 16).

I guess its the visualizing the wind that really gets me confused. I set the heading bug to sort reference where the wind is coming from which helps a lot.

But just wondering if I could get more tips on this. Anyone else had the same issue during their student days?

I fly a Cessna 172S.


texts: How can an aircraft’s maximum design operating speed be greater than its never-exceed speed?

texts:
According to this AAIB report on a June 2009 mid-air collision between an RAF Grob Tutor and a glider, the Tutor’s maximum design operating speed (VDO) is greater than its never-exceed speed (VNE):

(5) In the case of aerobatic category aeroplanes, allow each occupant to abandon the aeroplane at any speed between VSO and VDO10;  [Quoting the applicable certification requirements for aircraft emergency exits; footnote in source.]

[...]
10 VDO is the maximum design operating speed which for the Tutor is 1.1 VNE or 205 kt.  [The report’s explanation of the aforementioned footnote.  The bolding is mine.  Everything I have quoted from the report comes from page 62 (numbered as page 52).]

The point of the never-exceed speed is, as indicated by its name, that this speed should never be exceeded in this aircraft for any reason whatsoever; as such, aircraft are generally designed and certified with maximum operating speeds well below VNE.  How can the Tutor’s design maximum operating speed be greater than its never-exceed speed?


texts: Why doesn't the pressure inside an airliner push the doors open?

texts:
When flying at cruise altitude, the pressure inside the aircraft is higher than outside and that means a lot of air is pushing the door outwards. So how does the door stay in place and not open?

I'm not asking if a passenger could open a door, because that's almost impossible. I'm asking how does the door not open if there is a lot of air pushing it outwards?


texts: What was the speed limitations for droop nose on the Concorde?

texts: Lowering gears or extending flaps comes with limitations. Given the answer of this question I suppose the limit speed for full nose down is about 325 kt. My question is: what were the limit for all positions (visor down but nose full up, nose in take off position, nose in landing position, any other position I don't know)?


texts: (See Included ILS Chart) What to Do After SMT RDL 084?

texts:
Below is a screen grab from the ILS RWY 25R approach chart for HKG/VHHH. What should the plane do after passing SMT radial 084 (or TD D8 NM)?

It doesn't look like immediately turn heading 253 degrees; from an algorithmic point of view does the plane do an RNAV from PLOVE to RIVER, then track SMT radial 253 after RIVER? Or does it start to track SMT 253 right after SMT radial 084?

Also, what does "ITFR" stand for in this graph? The ITFR distance measures from the east and west side of the runway are based on two different ILS localizers, is that correct? Thanks!

(Source: AD 2-94A, Aeronautical Information Publication, Hong Kong Aeronautical Information Services)


texts: Why does the use of reverse thrust on the DC-8 generate a pitch-up moment rather than a pitch-down moment?

texts:
Unlike most aircraft, the DC-8 is certified to use reverse thrust in flight (albeit only on its inboard engines). This serves as a very effective airbrake, although it also produces considerable buffeting (due to the large areas of separated and/or reversed airflow it produces over the wing’s surface).

It also, more interestingly, produces a pitch-up moment (at least according to the CAB AAR on the crash of EA304):

  [...]  The pilots in this case, if the drive system failed during a PIO rather than earlier, had no way of knowing the real reason for its failure to operate in the ANU direction.  In the split seconds available to them for analysis they could easily have concluded that the failure was due to heavy stick forces.  Reverse thrust, in addition to drag, produces a nose up pitching moment, a fact known to the first officer if not to the captain, and as indicated previously, they did employ this aid.  It is also true that during the time, no matter how short, required to go from forward thrust to reverse, the noseup pitching moment of forward thrust has been removed and therefore contributes to the severity of the dive.  Small as it may be, this factor becomes more significant at very low initiating altitudes.  [Page 25 of the aforementioned AAR; my emphasis.]

For an aircraft with engines mounted below the aircraft’s center of mass, like the DC-8, only the use of forward thrust would be expected to produce a pitch-up moment (due to the torque exerted by the offset net thrustline), and reverse thrust should produce a pitch-down moment (for the same reason):

Yet, for the DC-8, the use of reverse thrust not only creates a nose-up pitching moment, but, apparently, creates one that is stronger than that produced by forward thrust!

Why?


texts: Why is the circulation around a centrifugal impeller blade tip the opposite to a wing tip?

texts: Why does the circulation around a centrifugal pump blade tip go from low pressure to high pressure as an effect of the slip caused by the non-uniform velocity distribution (the opposite of a wing tip). The reason stated in my book says that below the blade there is low pressure leading to high velocity and vice versa for the part above the blade. In an airplane, there is vortex at wing ends where air moves from below(high pressure) to above(low pressure) as given in the diagram.


texts: Can I log multi-engine time abroad, when I'm not rated for multi in that country?

texts:
I hold a multi-engine FAA CPL and want to fly a multi-engine aircraft in another country. The aircraft is not N-registered and I don't have a multi-engine rating in that country. Can I log the time in my FAA logbook? I'd like to log the hours under my FAA license.

More Details:
Country: Colombia (ICAO)
Role: Second in Command

The plane is a multi, I don't have multi license from the registration's country but I have FAA Multi license, so the idea is to fly it and log the hours using my FAA license can I do that ? Even if I don't have the license to fly that plane from the country of the registration ?


texts: Did I identify these aircraft correctly?

texts:
I photographed a couple of aircraft and tried to identify them, but I'm not sure if it's correct. For me, all of them look like an Airbus A320, but I'm really unsure. So which of these aircraft is an Airbus A320 and if not, what's the correct type?

Airbus A320?

Airbus A320?

Airbus A320?

Airbus A320?


texts: How do flight crew train/demonstrate ditching evacuation?

texts:
In case of evacuation, flight crew can train and demonstrate their ability with a real plane and test passengers.

However; how can one be trained in case of ditching ?

Obviously, it would be quite problematic to ditch an aircraft just for training/demonstration purpose...


texts: What are the services that MROs provide for corporate jets (private jets)?

texts: What are typical Costs/Rates of Private(corporate jets) MRO Services in the Middle East/North Africa region?


texts:
Is it legal for large, multi-crew, aircraft (such as the A380 or B747) to go VFR? I would guess it's legal just as any other aircraft. Is this ever done, like during training or test-flights? If it isn't legal, what's the limiting factor?

I'm talking real VFR from take-off to landing, not an VFR-on-top IFR clearance.

As I don't have a spare 747 sitting around waiting for me to take it out for an afternoon spin, I'm interested more in the general sense, is it legal anywhere, and are airlines taking advantage of it?


texts: Can I get a FAA medical certificate and apply in an Indian airline?

texts:
I am an Indian, and was wondering if I could get an FAA medical certificate and apply in an Indian based airline.

Is there a problem if I do that? Should I get the DGCA medical certificate itself?


texts:
50°01'59.15" N 8°34'05.10" E

What are those markings on runway 25L at Frankfurt Airport?

UPDATE:

July 2016 imagery shows the runway as closed, top image is c. 2015.


texts: Do multiple go-arounds on the same flight happen in commercial aviation?

texts:
I know that go-arounds are pretty rare: somewhere around 2 per 1000 approaches. In large commercial aircraft the rate is probably even lower due to crew quality, instrumentation, conservative decisions etc.

But are there instances of multiple go-arounds having to be initiated by a flight crew on one flight? I'm just curious to hear of any such stories. Two GAs? Three GAs?

I suppose if the reason is Weather related or equipment related the chance of a multiple go around might exist?

A related question is after how many weather related go-arounds would the crew decide to divert to the alternate. Either by rule, company procedure or plain heuristics.

P.S. Let's restrict this to non-training flights by scheduled airlines.


texts: Are GA airports typically accessible 24/7?

texts:
Is access to GA airports 24/7?

I always thought it was.   Every airport I've visited had gate-codes to open gates after hours.

But I recently started planning a flight to Salina, KS (KSLN), and the local FBO told me field access shuts down entirely at 10p.m.

As a transient flight, I'd have no way back to my plane after that.  I'm skeptical, as I believed airport access was 24/7.

Am I just completely mistaken in that belief?


texts: Where is the regular wheel brake input on modern airliners?

texts:
I learned that on modern airliners, the Rudder input is given by the pedals located under the pilot's feet, and that got me thinking:

how do the pilots give the command to brake the plane in order to slow it down on ground (landing/taxing)?
Is the parking brake and "regular" wheel brake part of the same system?


texts: Why is there a pitching moment at aerodynamic center?

texts:
As far as I know, the pitching moment is an aerodynamic moment and is related to the aerodynamic center.
But I am confused with the following figure, which shows the aerodynamic force applied at the aerodynamic center. So I would think, in this case, that the center of pressure is located at the aerodynamic center which is a quarter chord. If so, why is there a moment ?

https://wright.nasa.gov/airplane/Images/ac.gif


texts: Is there a 3rd-party API for aviation weather forecast, which includes additional cloud information?

texts:
I posted this question on StackOverflow here and terriblememory suggested I post it here.  I didn't even know there was an aviation stack exchange.  Cool!

  I have been scowering the internet all day for a third-party weather
  API that reports more than just the cloud coverage for cloud
  information.  I need to know the height of the cloud.

  I need something like an aviation weather API that reports either the
  cloud height, the cloud max and min vertical position, or the cloud type (Cirrus, Stratus, Cumulus, etc.) from which we could then derive the relative height.

  We want the API to be free at least during development.

I found some relative information in this stack exchange and one answer here that tells how to find the cloud tops but I'm posting this question anyway in case there is an API yet to be suggested.

Meanwhile, I'll be taking a look at the other information I found in this stack exchange.  Thank you in advance for suggestions.


texts: Why is "dragging it in" considered bad in small aircraft, but fine in larger aircraft?

texts: In larger aircraft, shallow, high-power approaches are performed as a matter of routine, but in light aircraft it seems to be frowned upon, especially in clear weather and smooth fields. Why is "dragging it in" considered bad in small aircraft?


texts: How can leading edge separation bubbles be prevented?

texts:
I have an airfoil (S3010, 9% thickness) that gives the resulting Cp distribution at 2 degrees and Re=500k.

I suspect that the abrupt increase in pressure before the suction peak is a separation bubble. I've read somewhere that this behaviour is common for thin airfoils.

How can I modify the airfoil to prevent leading edge separation?
The end goal is to increase the L/D


texts:
It has often been said on this site that induced drag on wings is the inevitable result of producing lift over a finite length. Converting this to the realm of propulsion, I assume that propellers have "induced drag" or something similar, as they produce thrust over a finite length.

With a ducted fan, the airstreams above and below the airfoil can't just "slip around the side," because they're blocked by the duct. My intuition thus suggests that ducted fans would not have induced drag (or its equivalent), assuming that the space between the blades and the duct is negligible.

Is this accurate?


texts: Is there a database from which I can retrieve the Expected Crossing Altitudes of a Departure or Arrival Procedure?

texts:
I am stuyding FAA's Coded Instrument Flight Procedures (CIFP) file which uses ARINC 424 digital format to code its data. I noticed that only mandatory crossing altitudes and speeds are included in the coding of the Arrival procedures (STARs), whereas expected crossing altitudes and expected speeds are omitted.

Take for example JFK's CAMRN arrival procedure. There are two assigned expected altitudes and one expected speed: at HOGGS (FL180) and at CAMRN (11000, 250K). The corresponding coded procedure in the CIFP file is:

Is there any reason that these values are omitted? Is there any other source where I can find these missing values? One would think that the expected crossing altitudes and speed are an important part of a procedure and thus I find it difficult to understand why they are not included in the CIFP file.

If I would like to study an arrival procedure's vertical profile but there aren't any assigned crossing altitudes, what is the most appropriate way for estimating actual, or, at least, realistic crossing altitudes (e.g. for design purposes)?


texts: When wiil this person be able to replace his engines on a bunch of smaller ones to attach them on clothes?

texts:
That is the real question that bothered me.
 UK 'Iron Man' suit


texts: Can airplanes transmit/relay flight data to ATC's periodically while in flight?

texts: The flight data recorder is one important piece of information in the event of a crash. Can this information not be transmitted or relayed to the ATC's while the flight is air borne so that they don't have to wait to recover the data recorder after a crash ? I mean to say that periodically the data can be sent back to a ground controller when the signal strength is high and it can be logged. Please let me know if there are any limitations to the amount of data that an air borne flight can relay back to the controller.


texts: Is it possible to upgrade old Mirage-III and Mirage-V variants with thrust vectoring engines?

texts: Is it possible to upgrade old Mirage-III and Mirage-V variants with thrust-vectoring engines so that they can match the maneuverability of F-16s?


texts: I know that ALL airports that have received federal funds are considered to be open to the public, however does that mean that every "public" airport was federally funded?


texts: Why are the throttle levers for the Comet's outboard engines shaped funny?

texts:
The throttle levers for the Comet's outboard (#1 and #4) engines are weirdly shaped, with flanges that extend up and partially over the throttle levers for the inboard (#2 and #3) engines:

(Image cropped and annotated by me; original by Geni at Wikimedia Commons)

Why are the Comet's outboard throttle levers shaped like this?


texts: How precisely are airspace borders defined?

texts:
I'm studying for the commercial drone certificate. In Tucson, AZ the class C airspace covers about half of the city, but the charts don't list the exact point that it ends. Here's a portion of the VFR chart:

How exact are these airspace borders? Could one city block north or south get me in trouble if I don't check in with ATC?


texts: On the flight that I was on today, one of the passengers near me asked this question. Why don’t airplanes use lap- and shoulder belts like cars do?


texts: Does an airplane has to take off from beginning of the runway or it can take off from displaced threshold?

texts: I mean, if the airports declared that there is a displaced threshold of runway ; and airplanes use this length for landing but how about for takeoff?


texts: How can a large passenger aircraft's owner remain unknown?

texts:
I'm reading through TheStar's "Malaysia Airports seeks owner of three Boeing 747s abandoned at KLIA" article and I can't stop wondering, why I don't understand it or how should I understand it?

How it is possible in 21th century, that knowing large passenger aircraft's (a) type, (b) current location and (c) registration it is still impossible to find actual aircraft's owner in a matter of minutes?

Don't we have aircraft's databases, to obtain this information? Or to use it to track any passenger aircraft latest flights? Is it possible, that Kuala Lumpur International Airport does not have any records or tracks of what (owned by whom) and when landed on their grounds?

I know that this isn't possible, but for a newbie like me this article sound like a joke rather than a current reality in aviation industry today.


texts: Does the size of code F aircraft parking apron enough for 2 code C plane?

texts:
When I look at Inner Thames Estuary Airport (Isle of Grain) masterplan, they shows a funny figure about the terminals layout.

The report describes that  It shows the ability for most
stands to handle either a large wide bodied (Code E/F) aircraft or two narrow bodied (Code C) aircraft.

The question is, is it true?


texts: What can I learn before I actually go to flight school (Austria)?

texts:
I am currently occupied with a large project which basically eats up all my money but will be done in a year or so. After that, I would like to get my PPL. So I am currently out of money but do have some time left which I would like to use to already study the basics.

Is there any freely available material targeting PPL training? I live in Western Austria if that is of any concern (this is also where I would like to perform any training - LOIH is closest to my location).


texts: Where to find information on ILS categories at European airports?

texts: I have a list of airports in Europe and I need to find up-to-date information about ILS categories (I, II, IIIa, IIIb or IIIc) at these airports. Does anyone know where I could find such data efficiently?


texts:
On a recent commercial flight (A320neo), I noticed some materials attached to the leading edge of a slat (no photo available). The attached material was not smooth, it rather looked like a small ball of steel wool. Making pilots aware of it, I was told this was a temporary repair for a dent.

I was satisfied for the moment, but rethinking the matter later, I wondered if dents can be temporarily fixed by spoiling the airflow, I would rather have expected a smooth foil or plate to restore the nominal flow. The aircraft continued its next legs without noticable delay.

How are dents in wings temporarily fixed?

Can pilots judge, if a damaged fix is within allowable limits?


texts: How does angle of attack vary during climbing flight?

texts:
I'm a little confused by the angle of attack of an aircraft during climbing flight. Suppose you have an aircraft in level flight which then rotates to some angle x. Just after rotation, I would assume that the angle of attack is equal to x, but after this I get confused. The aircraft continues to climb at the angle x, but does the angle of attack vary with time spent in climbing flight? Or once the rotation is over does the angle of attack go back to whatever it is for steady level flight?

Similarly, if you have an aircraft travelling at steady level flight with net lift = 0N, which then rotates to some angle x where for an angle of attack x the net lift is 50N. Does the aircraft only experience this extra 50N of lift for a brief moment during/after rotation, and following that the net lift acting on the wings is again 0N?


texts: How does a Machmeter behave if the static port is blocked during a constant CAS climb?

texts:
Question: How will the machmeter behave in a constant CAS climb if  the static source becomes blocked?
Answer: The machmeter reading will decrease.

Why? I couldn't find any logical reason for the machmeter reading to decrease. My understanding is that when CAS is constant during a climb, the TAS should increase. If the static source is blocked, this will only increase the TAS further to maintain same CAS because the static pressure outside is less than the pressure in the blocked static source.

I fail to understand how the local speed of sound (LSS) is related to a blocked static source. Because LSS is related to temperature only, so it decreases during a climb.

That means that Mach speed = TAS (increasing) / LSS (decreasing) = overall increase in Mach speed

What am I missing?


texts: I have sent letters requesting action and/or clarifications to the FAA medical certifications branch.  How long can FAA legally delay before they are required to answer my questions in writing?


texts: Is this new intake of Airbus and Boeing aircraft's NACA inlet?

texts:
Anybody knows the name of this intake? look at the bellow images:

Why don't Airbus and Boeing use the conventional NACA inlet? Why did they invent this kind of intake? I can see some parts of these aircraft that the conventional NACA inlet are embodied in.


texts: Is there a way to determine maximum rpm for axial compressor due to material limitations?

texts:
I'm looking for RPM to Stress relation to determine maximum rotational speed that compressor/turbine blades can have without undergoing deformation due to centrifugal tensile stress.

I've come come across this relation but I'm not sure if its correct one:
$$ v_t = \sqrt{\frac{\sigma}{\frac{1}{2} \times \rho \times \left[ 1 - \left( \frac{\Omega_h}{\Omega_t} \right)^2 \right]}} $$
where:

$\sigma$ is the stress (tensile) of the material
$\rho$ is the material density
$v_t$ is the rotational speed of Rota
$\Omega_h / \Omega_t$ is the Hub-Tip ratio


texts: What is the reason for this unusual flight path?

texts:
Last week, flight AA9675 flew from MIA to TUL. It took this very unusual flight path:

It's an ad hoc flight number, so it's not a regularly scheduled flight. You can see there was a line of thunderstorms moving across at the time. But that alone does not explain the route. FlightAware shows the flight plan that was filed.

After leaving Miami it skipped the first few filed waypoints. But after it left Florida it followed the plan as filed from one VOR to the next, in a big circle around the Midwest and finally landing in Tulsa.

My only guess as to the reason for such an unusual route is that, due to the line of storms, it's some kind of contingency flight. Maybe they were anticipating delays and kept a plane airborne so that it could be quickly re-routed if necessary. I've been told that FedEx does this during peak season, but I've never heard of a passenger airline doing it.

Does anyone have an explanation for such an unusual flight path?


texts:
Why is fuel used in some servo-systems as a hydraulic fluid (fueldraulic systems) of modern civil and military aircraft such as the Boeing 777-200/-300 (Pratt & Whitney PW4084) or the Lockheed Martin F-35 Lightning II (Pratt & Whitney F135)?
Examples for fueldraulics are the actuation of

Fuel Valves, Start Bleed Valves, Cooling Valves,
Variable (Inlet) Guide Vanes (VGV/VIGV) / Variable Stator Vanes (VSV) for the compressor, and
Thrust Vectoring Exhaust Nozzles,

see for example Eder, M.: "Engine Fuel System Design Issues", Aviation Fuels with Improved Fire Safety, A Proceedings, 1997.

Here is a sketch of a fueldraulic system actuating the Bleed Valve and the VIGVs for a compressor, taken from "Rolls-Royce plc: The Jet Engine, 5th Edition 1996, Derby, England, ISBN 0902121235":

Are there specific reasons for not using designated hydraulic fluids such as Skydrol for all hydraulic applications?


texts: How to calculate the location of C.G. A.C. & N.P. in static longitudinal stability?

texts:
We are in the conceptual stage of design and, using Raymer & Nicolai as references, I am doing a rough calculation of "power off" neutral point (N.P.) to find the optimum c.g. and a.c. positions.

As seen in this photo, which is also reflected in Nicolai, when doing a static longitudinal stability analysis, the moments are summed assuming the c.g. is aft of the wing/body a.c. and the tail provides a negative moment (nose down) while the wing provides a positive moment. It assumes both tail and wing provide positive lift. I understand that in this configuration, the positive tail lift would shift the overall a.c. (neutral point) aft and the c.g. would just need to be in front of the neutral point for static stability.

However, what is confusing for me is that conventional stability usually involves placing the c.g. in front of the a.c. and n.p. so that the wing provides a negative moment (pitch down) and the tail stabilizes this by providing a negative lift (down force) to pitch the nose up. Why assume the c.g. is aft of the a.c. and the tail is providing positive lift? Why not sum the moments assuming the c.g. is in front of the a.c. for calculating neutral point?

Any help would be much appreciated, thanks!


texts: Does any company (or country) still use Zeppelins or airships? Why not?

texts:
I just like them a lot when I see'em in movies and I was wondering, are they still being used anywhere? Are there any companies working on them?

If the answer is, as I expect, "Nope", I have to ask why?
(Update: the "why" is more or less explained here Why are airships not more popular? , I still hope the answer is not "Nope"!)

Naïvely I would've thought they should be useful for heavy cargo, passengers, cheaper and safer than planes...


texts: How can someone get FAA commercial flight training as part of an aviation degree?

texts:
If someone can't afford to pay for flight training directly, is it possible to get commercial flight training with financial aid as part of a college degree?

For the UK answer, see: Do any UK universities include PPL/Commercial flight training as part of an aviation degree?


texts: How to find coordinates of the geometric center of a NACA 4-digit airfoil?

texts:
For a project that my team and I are working on, we are using Autodesk Inventor Professional 2018 (student license) for 3D modelling. We are working on NACA airfoils.

I need to create an airfoil within an airfoil so that the thickness distribution is uniform at around (10/12/15)mm.

To do this modelling, I've used two methods, neither of which is satisfactory. Please advise if using geometric center of airfoil is better than aerodynamic center. And how to find it. Please suggest any other method to get the uniform thickness distribution.

Use a NACA 6415, c=600mm and NACA 6412, c=580mm. Superimpose their aerodynamic centres.

The issue with this method is that thickness is more at Trailing Edge (TE) than at Leading Edge (LE).

Use a NACA 6415, c=600mm and scale it down to 0.85 with respect to the aerodynamic centre.

Issue with this is that the thickness variation is too high.

Cross posted at researchgate


texts: Are there winglet modification regulations?

texts: If an already existing fleet (737-800 and 900 without winglets) is thinking of a winglet modification, is that possible without regulations? Or what are the regulations?


texts: What are the names of these aircraft? Part.2

texts: The next part of the group... Can someone help me?


texts: Feasibility of converting long body carriers into stationary field hospitals

texts:
Considering the current pandemic crisis, and the fact that and there are thousands of grounded planes that can be put to other uses, I come with a somewhat dumb question.

Is it possible to remove seats in a long-body passenger carrier to, instead of flying with two hundred cramped passengers, make it spacely enough to carry forty or fifty narrow beds and a small staff to take care of them, while stationary on the ground?

Is it feasible, from an economic viewpoint, to pay air companies for this, in comparison to actually building tents or renting buildings in a big town like New York or San Francisco?

EDIT

Yeah, I mean stationary planes, with external APU to power up the air conditioning and lights and rampies to take the waste away and constantly fill it with water.


texts: Where can I find a free/cheap small airplane wing?

texts:
I am looking for a small airplane wing (e.g. Cessna 172, but not necessarily) to run some experiments prior to seeking an STC for a modification I am working on. Do you know where I can find a free abandoned wing, or a very cheap one? It doesn't have to be airworthy or functional at all, as I will just use it for standalone tests on the ground.

Thanks!


texts: Why flaps can deflect up to 25°+ without stalling the wings?

texts: According to this graph,plain flaps have their highest Cl at about 2 and stalls at about 15°,my question is how then do airplane flaps reach 25°+ of delflection when this gragh clearly states that stall is at 15°?


texts: Why does my flightplan generator come up with a very non-direct route between these two airports?

texts: I'm currently obtaining my private pilot license and I had a random thought pass through my head so I wanted to see how long it would take to get from my airport (KGBR) to an airport in VA (KCHO). The flight plan provided is not as I expected which I assume its due to the busy airspace surrounding my flight. I was wondering why the flight path generator didn't give me a more direct route heading west and then south instead of bringing me down the coastline. Any insight would be appreciated!


texts: Is there a standard definition of the "stall" phenomena?

texts:
In the process of increasing angle of attack of a wing, lift is increasing to a maxima at a certain AOA, then decreasing as this AOA is exceeded.  This seems to be the current agreed upon definition of the stall point.

Yet the sharp pitch down and transition of the center of lift to 50% chord does not occur until the top lift pocket completely collapses.  Is this the true definition of "stall"?

There is also pre-stall buffeting as high AOA turbulence begins to affect the wing trailing edge.

So, are there really 3 parts to this that a pilot must understand, rather than just one?


texts: Is there a standard text for parachute design?

texts:
In some technology areas, there are "standard" texts - for GA type aircraft design, I think of Stinton's "Design of the Airplane". For radar, Skolnik's "Radar Handbook".

Is there an equivalent text for parachute / para-airfoil design?


texts: Is there a legal requirement for planes to start from the ground?

texts:
If I could somehow store a plane inside another plane, would I be allowed to start the second plane somewhere in the air? Maybe different countries have different laws for this kind of aviation?
I know that this is technically at least challenging if not impossible, I was just wondering if I would even be allowed to do this.
Bonus Question: How would the pilot communicate this to the authorities?


texts: What airport proposal(s) has London seen after WWII?

texts:
Instead of Thames Estuary Airport from Maplin in 70s to the latest inner Thames Estuary Airport, is there any proposal airport(s) raised after WWII but cancel/rejected eventually?

I know there is a airport proposal in the north-west London but it is cancelled eventually. Does anyone know about this?

In stead of these two, is there any other airport proposals?


texts: How Military to Civil Aircraft Transition is made by National Authorities?

texts: As we know military aircrafts are not regulated by civil aviation authority organisations,namely FAA, CAA and etc. Is there any possible way to transform a military aircraft( like helicopters) to civil ones? And if it is, where are these conditions mentioned?


texts: What is the purpose of the hold at JNC on the Grand Junction Seven SID?

texts:
There is a hold on the Grand Junction Seven SID.

I would expect it is there so that ATC could hold you until you reach the enroute MEA but there is no written reference.

So, what is the reason for the hold?  It is certainly not obvious from the plate or departure procedure.